CA1325115C - Patient interfacing system and method to prevent water contamination - Google Patents
Patient interfacing system and method to prevent water contaminationInfo
- Publication number
- CA1325115C CA1325115C CA000600193A CA600193A CA1325115C CA 1325115 C CA1325115 C CA 1325115C CA 000600193 A CA000600193 A CA 000600193A CA 600193 A CA600193 A CA 600193A CA 1325115 C CA1325115 C CA 1325115C
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000011109 contamination Methods 0.000 title abstract description 6
- 239000007789 gas Substances 0.000 claims abstract description 136
- 230000008016 vaporization Effects 0.000 claims abstract description 69
- 238000009834 vaporization Methods 0.000 claims abstract description 62
- 238000012544 monitoring process Methods 0.000 claims abstract description 28
- 238000004868 gas analysis Methods 0.000 claims abstract description 13
- 238000005070 sampling Methods 0.000 claims abstract description 9
- 239000007788 liquid Substances 0.000 claims abstract description 6
- 230000000241 respiratory effect Effects 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 18
- 229920000557 Nafion® Polymers 0.000 claims description 17
- 239000012528 membrane Substances 0.000 claims description 11
- 230000032258 transport Effects 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 6
- 238000012806 monitoring device Methods 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims 2
- 238000009833 condensation Methods 0.000 abstract description 4
- 230000005494 condensation Effects 0.000 abstract description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 238000005259 measurement Methods 0.000 description 8
- 230000004044 response Effects 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 6
- 238000013459 approach Methods 0.000 description 6
- 239000002274 desiccant Substances 0.000 description 6
- 239000003193 general anesthetic agent Substances 0.000 description 6
- 239000003994 anesthetic gas Substances 0.000 description 5
- 239000001569 carbon dioxide Substances 0.000 description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 238000001069 Raman spectroscopy Methods 0.000 description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 230000002209 hydrophobic effect Effects 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 230000029058 respiratory gaseous exchange Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 230000028327 secretion Effects 0.000 description 3
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000001815 facial effect Effects 0.000 description 2
- 230000036961 partial effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000036962 time dependent Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 206010002091 Anaesthesia Diseases 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229920000544 Gore-Tex Polymers 0.000 description 1
- 229920006243 acrylic copolymer Polymers 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000037005 anaesthesia Effects 0.000 description 1
- 230000003444 anaesthetic effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000002503 metabolic effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000036284 oxygen consumption Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000035755 proliferation Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 238000001356 surgical procedure Methods 0.000 description 1
- 230000004083 survival effect Effects 0.000 description 1
- 230000001225 therapeutic effect Effects 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N5/00—Radiation therapy
- A61N5/06—Radiation therapy using light
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/08—Measuring devices for evaluating the respiratory organs
- A61B5/083—Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Biomedical Technology (AREA)
- Engineering & Computer Science (AREA)
- Veterinary Medicine (AREA)
- Animal Behavior & Ethology (AREA)
- Public Health (AREA)
- General Health & Medical Sciences (AREA)
- Pathology (AREA)
- Obesity (AREA)
- Emergency Medicine (AREA)
- Heart & Thoracic Surgery (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Physiology (AREA)
- Biophysics (AREA)
- Pulmonology (AREA)
- Physics & Mathematics (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Radiology & Medical Imaging (AREA)
- Sampling And Sample Adjustment (AREA)
- Devices For Medical Bathing And Washing (AREA)
- Percussion Or Vibration Massage (AREA)
- Electrotherapy Devices (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Abstract
PATIENT INTERFACING SYSTEM AND
METHOD TO PREVENT WATER CONTAMINATION
Abstract Described herein is a patient interfacing system for sampling the inspired and expired gases of a patient and removing moisture from the sample. In one embodiment of the present invention, a patient link receives the gases from the patient's airway circuit and a vaporization section vaporizes condensed moisture in the sample. A
separator section allows the vaporized moisture component of the sample to exit the patient interfacing system before the gas sample reaches the monitoring instrument. A filter may also be utilized to prevent condensed moisture, particulates and liquids from entering the monitoring instrument. Thus, the patient interfacing system of the present invention provides a reliable, cost effective and efficient means for delivering gas samples to a monitoring instrument which reduces or prevents water condensation inside the gas analysis portion of the monitoring instrument.
METHOD TO PREVENT WATER CONTAMINATION
Abstract Described herein is a patient interfacing system for sampling the inspired and expired gases of a patient and removing moisture from the sample. In one embodiment of the present invention, a patient link receives the gases from the patient's airway circuit and a vaporization section vaporizes condensed moisture in the sample. A
separator section allows the vaporized moisture component of the sample to exit the patient interfacing system before the gas sample reaches the monitoring instrument. A filter may also be utilized to prevent condensed moisture, particulates and liquids from entering the monitoring instrument. Thus, the patient interfacing system of the present invention provides a reliable, cost effective and efficient means for delivering gas samples to a monitoring instrument which reduces or prevents water condensation inside the gas analysis portion of the monitoring instrument.
Description
-1- 132~115 PATIENT INTERFACING SYSTEM AND
METHOD TO PREVENT ~ATER CONTAMINATION
Field of the Invention This invention relates to a system and method of interfacing a patient with monitoring equipment that monitors inspired and expired gases, and more particularly, to a system and method for preventing condensed water or other liguids from entering the detection portion of the monitoring equipment.
Backaround of the Invention Respiratory and anesthetic gas monitoring has achieved a high standard of technological advancement with the development of monitoring techniques that enable quick diagnosis and treatment of unfavorable trends in the condition of a patient, improved survival rates, early extubation following surgery and shorter times in intensive care units. Applications of respiratory gas and anesthetic agent monitoring include the measurement of oxygen consumption, carbon dioxide production, anesthetic agent uptake and the detection of anesthesia machine circuit disconnections and introduction of air emboli into the blood. Continuous analy6is of patients' respiratory and anesthetic gases is becoming increasingly important in improving patient safety during the course of treatment.
For example, breath-by-breath monitoring of the concentrations and identity of the anesthetic agents present in a patient's respiratory gases ~eads to a more scientific basis for the admin~stration and control of the ; anesthetic agents.
Continuous, breath-by-breath monitoring of a patient's respiratory gases and 6imultane~us determination of multiple specific respiratory gases and ane~thetic agents in the patient' 6 system can often facilitate diagnosis and treatment, anticipate and prevent the development of : .
METHOD TO PREVENT ~ATER CONTAMINATION
Field of the Invention This invention relates to a system and method of interfacing a patient with monitoring equipment that monitors inspired and expired gases, and more particularly, to a system and method for preventing condensed water or other liguids from entering the detection portion of the monitoring equipment.
Backaround of the Invention Respiratory and anesthetic gas monitoring has achieved a high standard of technological advancement with the development of monitoring techniques that enable quick diagnosis and treatment of unfavorable trends in the condition of a patient, improved survival rates, early extubation following surgery and shorter times in intensive care units. Applications of respiratory gas and anesthetic agent monitoring include the measurement of oxygen consumption, carbon dioxide production, anesthetic agent uptake and the detection of anesthesia machine circuit disconnections and introduction of air emboli into the blood. Continuous analy6is of patients' respiratory and anesthetic gases is becoming increasingly important in improving patient safety during the course of treatment.
For example, breath-by-breath monitoring of the concentrations and identity of the anesthetic agents present in a patient's respiratory gases ~eads to a more scientific basis for the admin~stration and control of the ; anesthetic agents.
Continuous, breath-by-breath monitoring of a patient's respiratory gases and 6imultane~us determination of multiple specific respiratory gases and ane~thetic agents in the patient' 6 system can often facilitate diagnosis and treatment, anticipate and prevent the development of : .
oncoming pr~blems, and otherwise provide instant data for physicians and other health care personnel to use in therapeutic situations. Measurements of any gas of interest in a patient' B breath can be e~opled on a continuous basis and monitored by an appropriate type of gas analyzer. For example, when monitoring a patient' 6 carbon dioxide level, a ~harp reduction of carbon dioxide in the breath might indicate ~n imminent failure of respiration. Similarly a 6harp increase in the level of - lo carbon dioxide mig~t be an indication of other conditions requiring attention.
Respiration monitoring of patients is now available utilizing many types of commercially available gas analyzers including infrared (IR), polaragraph, mass spectrometer (MS), Raman spectrometer, etc. Due to the high cost of ~ome of the monitoring equipment, a ~ingle monitor may be connected to 6everal patients simultaneously. In many of these situations, the gas analyzer is placed in a remote location and lengthy capillary tubes are used to connect the patients to the analyzer unit. Since it is common practice to humidify ~nspired gas, and since the expired gas from the patient is often at nearly 100% relative humidity and 37 degrees - centigrade, water can easily condense at room temperature in the tub$ng interfacing the patient with the analyzer.
Virtually all commercially available gas analyzers ~e.g., IR, polaragraph, MS, Raman spectrometer, etc.) are adversely affected if condensed water or other liquids enter the detector portion of the analyzer. Additionally, the presence of water vapor in samples of expired gas can be a 60urce of error when making measurements of expired gas concentrations.
One prior method for removing water vapor from expired gases prior to analysis physically drys the expired gas, for example, by introducing the expired gas into a desiccator. one such system has been developed using a desiccator filled with calcium sulfate (CaS04) as the 132~
Respiration monitoring of patients is now available utilizing many types of commercially available gas analyzers including infrared (IR), polaragraph, mass spectrometer (MS), Raman spectrometer, etc. Due to the high cost of ~ome of the monitoring equipment, a ~ingle monitor may be connected to 6everal patients simultaneously. In many of these situations, the gas analyzer is placed in a remote location and lengthy capillary tubes are used to connect the patients to the analyzer unit. Since it is common practice to humidify ~nspired gas, and since the expired gas from the patient is often at nearly 100% relative humidity and 37 degrees - centigrade, water can easily condense at room temperature in the tub$ng interfacing the patient with the analyzer.
Virtually all commercially available gas analyzers ~e.g., IR, polaragraph, MS, Raman spectrometer, etc.) are adversely affected if condensed water or other liquids enter the detector portion of the analyzer. Additionally, the presence of water vapor in samples of expired gas can be a 60urce of error when making measurements of expired gas concentrations.
One prior method for removing water vapor from expired gases prior to analysis physically drys the expired gas, for example, by introducing the expired gas into a desiccator. one such system has been developed using a desiccator filled with calcium sulfate (CaS04) as the 132~
drying agent. Such desiccator ~y6tems experience at least two significant problems. Fir6t, the drying agent must be carefully monitored and replaced on a regular ba~i6 when it is depleted. Second, the large desiccator voluce required to perform the drying of the gas make6 for increased dead 6pace within the 6ystem and thus re6ult6 in longer "washout times" for measuring changes in gnseou6 composition. The term dead 6pace refers to any epace in the sy6tem between the point where the ~ample $s tapped from the patient and the point at which the ~ample enter6 the gas analyzer. Thi~
would include the space with~n the connecting tubes, filters, desiccants, valves, traps etc. The term "washout time" refers to the amount of time which is needed for a unit of gaseous sample to wash out or displace the gas already within the system.
Washout time is an important factor in monitoring changes in the concentrations of oxygen, carbon dioxide, anesthetic agents and other constituents of the patient's inspired and expired gases. Where large total volumes or dead volumes are present within a metabolic gas monitoring system, corresponding large washout times are created, resulting in decreased ability to quickly and accurately measure time dependent changes in the composition of the inspired and expired gases. The long washout t~m~s associated with desiccator cystems do not allow for the dynamic response necessary to measure time dependent ~- changes in the oxygen and carbon dioxide concentrations in breath-by-breath analysis of expired gas. The large total volumes and dead volumes of desiccator 6ystems have resulted in less sensitivity to changes in the composition of the gases analyzed and less accurate measurements of the oxygen, carbon dioxide and anesthetic agent components of the gases. Thus, 6ystems which use drying agents to remove the water vapor often requ~re frequent replacement of the drying agent and often introduce long delay times in the sampling line precludinq the acquisition of breath-by-breath data. Additionally, in 60me applications, the ' drying agent may absorb the gas being monitored and lead to inaccurate measurements.
Another common technique for removing moisture, patient secretions and other liguids from gas samples `- 5 employs cold traps in the gas line to condense the moisture. Condensation techniques have generally not been completely successful due in part to the excessively lnrge - dead epaces which are added to the gas transport system by the cold traps. The large dead space and long washout time problems previously described with respect to desiccator systems also apply to cold trap sy6tems.
One such cold trap system is described in the article entitled "A DRYER FOR RAPID RESPONSE ON-LINE EXPIRED GAS
MEASUREMENTS" by N.S. Deno and E. Xamon. This article discloses a water condensation ~ethod for drying an expired gas 6ample before it reaches an analyzer. The disclosed method utilizes a dryer which consists of an ice bath condenser and a separator for removing the condensed water.
As with other cold trap condenser devioes, this approach ` 20 has long response times which reduce the utility of the device for breath-by-breath analysis measurements.
~ The article entitled NELIMINATING THE EFFECT OF WA~ER
:~ VAPOR IN RESPIRATORY GAS ANALYSIS" by Larry G. Wong and Dwayne R. We6tenskow reports a method for partially eliminating water vapor from expired air ~amples by cooling the gas samples to a known temperature. This technigue substantially minimizes the effects of water vapor pressure on 2 measurements. Based on Dalton' 6 law of partial - pressures, the vapor pressure of water at a given temperature and pressure is constant and is independent of other gas concentrations. The effects of ~ater vapor in expired gas analysis are reduced by bringinq all sampled gases to a specific l~wered temperature. By reducing the temperature of the saturated gas ~ample to a known temperature, the water vapor partial pressure may be determined. Thus, when gases are sufficiently equilibrated with temperature in an appropriate apparatus, water vapor 132~
pressure i6 constant. However, the above-de6cribed 6y~tem is not 6uited for breath-by-breath measurement6 because large dead 6paces degrade 6everal de6ired performance characteristics including response time. Furthermore, this ~y6tem, while removing a ~mall guantity of ~oi~ture from the 6ample, i6 not primarily a water removal ~y6tem and allows most of the water vapor contained in the gas ~ample to enter the gas analyzer.
U.S. Patent No. 4,090,513 entitled "~EAT AND MOISTURE
EXCHANGING DEVICE FOR RESPIRATION" disclo6e6 a device for removing moisture from a tube carrying respiratory air.
The moisture accumulates on an exchange layer and fl~ws out of the device through a drainage tube. As with other condensation moisture removal 6ystems, decreased response - 15 time and water removal con6iderations limit the applications for which this 6ystem is 6uitable.
Another approach for preventing liquid6 from reaching a monitoring device is disclo6ed in U.S. Patent No.
would include the space with~n the connecting tubes, filters, desiccants, valves, traps etc. The term "washout time" refers to the amount of time which is needed for a unit of gaseous sample to wash out or displace the gas already within the system.
Washout time is an important factor in monitoring changes in the concentrations of oxygen, carbon dioxide, anesthetic agents and other constituents of the patient's inspired and expired gases. Where large total volumes or dead volumes are present within a metabolic gas monitoring system, corresponding large washout times are created, resulting in decreased ability to quickly and accurately measure time dependent changes in the composition of the inspired and expired gases. The long washout t~m~s associated with desiccator cystems do not allow for the dynamic response necessary to measure time dependent ~- changes in the oxygen and carbon dioxide concentrations in breath-by-breath analysis of expired gas. The large total volumes and dead volumes of desiccator 6ystems have resulted in less sensitivity to changes in the composition of the gases analyzed and less accurate measurements of the oxygen, carbon dioxide and anesthetic agent components of the gases. Thus, 6ystems which use drying agents to remove the water vapor often requ~re frequent replacement of the drying agent and often introduce long delay times in the sampling line precludinq the acquisition of breath-by-breath data. Additionally, in 60me applications, the ' drying agent may absorb the gas being monitored and lead to inaccurate measurements.
Another common technique for removing moisture, patient secretions and other liguids from gas samples `- 5 employs cold traps in the gas line to condense the moisture. Condensation techniques have generally not been completely successful due in part to the excessively lnrge - dead epaces which are added to the gas transport system by the cold traps. The large dead space and long washout time problems previously described with respect to desiccator systems also apply to cold trap sy6tems.
One such cold trap system is described in the article entitled "A DRYER FOR RAPID RESPONSE ON-LINE EXPIRED GAS
MEASUREMENTS" by N.S. Deno and E. Xamon. This article discloses a water condensation ~ethod for drying an expired gas 6ample before it reaches an analyzer. The disclosed method utilizes a dryer which consists of an ice bath condenser and a separator for removing the condensed water.
As with other cold trap condenser devioes, this approach ` 20 has long response times which reduce the utility of the device for breath-by-breath analysis measurements.
~ The article entitled NELIMINATING THE EFFECT OF WA~ER
:~ VAPOR IN RESPIRATORY GAS ANALYSIS" by Larry G. Wong and Dwayne R. We6tenskow reports a method for partially eliminating water vapor from expired air ~amples by cooling the gas samples to a known temperature. This technigue substantially minimizes the effects of water vapor pressure on 2 measurements. Based on Dalton' 6 law of partial - pressures, the vapor pressure of water at a given temperature and pressure is constant and is independent of other gas concentrations. The effects of ~ater vapor in expired gas analysis are reduced by bringinq all sampled gases to a specific l~wered temperature. By reducing the temperature of the saturated gas ~ample to a known temperature, the water vapor partial pressure may be determined. Thus, when gases are sufficiently equilibrated with temperature in an appropriate apparatus, water vapor 132~
pressure i6 constant. However, the above-de6cribed 6y~tem is not 6uited for breath-by-breath measurement6 because large dead 6paces degrade 6everal de6ired performance characteristics including response time. Furthermore, this ~y6tem, while removing a ~mall guantity of ~oi~ture from the 6ample, i6 not primarily a water removal ~y6tem and allows most of the water vapor contained in the gas ~ample to enter the gas analyzer.
U.S. Patent No. 4,090,513 entitled "~EAT AND MOISTURE
EXCHANGING DEVICE FOR RESPIRATION" disclo6e6 a device for removing moisture from a tube carrying respiratory air.
The moisture accumulates on an exchange layer and fl~ws out of the device through a drainage tube. As with other condensation moisture removal 6ystems, decreased response - 15 time and water removal con6iderations limit the applications for which this 6ystem is 6uitable.
Another approach for preventing liquid6 from reaching a monitoring device is disclo6ed in U.S. Patent No.
4,485,822 entitled "MULTI-PHASE INTERFACING SYSTEM AND
METHOD". This patent di6closes a patient interface which relies on a disc-~haped hydrophobic filter to prevent fluids from entering the analyzer. This 6ystem overcomes the poor response time of most cold trap ~nd desiccator ystems by using a low dead 6pace volume disc filter. In 6uch an interface, however, in the event that the patient requires a humidifier, enough water can condense within the filter to occlude gas flow through the filter. In 60me cases, tbis can occur within 30 minute&, depending on the gas flow rate to the analyzer and the ambient temperature.
Not only i8 this inconvenient for the medical 6taff and patient, 6ince the filter must be changed freguently, but this can also result in a loss of vital medical information during the time period that the filter is being changed.
~. S. Patent No. 4,549,553 entitled ~APPARATUS AND
METHOD FOR USE IN A MEDICAL GAS SAMPLING SYSTEM", discloses an approach for providing a 6ample gas flow from ~n air tube to a patient undergoing automatic ventilation. The 132511~
air tube includes a gas diffusive membrane disposed in a wall of the air tube. The qas diffusive Dembrane may be made of water absorbing or water pa6sing materials to eliminate excess water from accumulating and bloc~ing the gas sample flow. In a preferred embodiment a non-wettable gas diffusive membrane is used to prevent or reduce water from entering the sample gas flow; otherwise, water caturates the membrane and water eventually pas~es through the membrane to enter the gas ~ample flow. By non-wettable it is meant that the membrane resist6 or cannot be - saturated with liguid and it6 curfaces resist or cannot be covered with liguid. A Teflon mesh membrane is a 6uitable non-wettable membrane for this application. Teflon i6 a registered trademark of E.I. Du Pont de Nemours & Company, Inc in Wilmington, Delaware. This approach, while perhaps ~ reducing the frequency of sample flow blockage, does - nothing to remove the moisture from the system and is 6till 6usceptible to occlusion in long term usage. AdditiGnally, the embodiment shown in Figure lA incorporates a large volume funnel 20 which increases the dead 6pace volume in the gas transport 6ystem and results in poor response time characteristics.
A more recent approach for preventinq water from condensing in the gas transport circuitry uses interface tubinq comprising a polymer that i6 highly permeable to water vapor, but simultaneously has a very low permeability for the respiratory and anesthetic gases being ~nalyzed.
One such polymer was developed by Du Pont scientists and is marketed in tubing form as Nafion tubing. Nafion is a registered trademark of E.I. Du Pont de Nemour6 & Company, Inc. in Wilmington, Delaware. By attaching the Nafion tubing directly to the patient breathing circuit near the connection to the patient, a ma~ority of the water vapor in the 6ample gases diffuses out before it arrives at the filter barrier. The disadvantage of this approach is the high cost of the Nafion~ tubing. A 6ection of Nafion~
tubing of 6ufficient length to remove the desired amount of 132~
water vapor is very expensive in relation to the cost of the other components comprising the patient interface.
Therefore, it is generally considered a reusable rather than a disposable gas samplinq line and, a~ uch, requires cleaning and sterilization between uses.
~ any of the attempts heretofore to remove liguids from patient interfaces introduce levels of dead ~pace into the - interfacing ~ystem which adversely affect the accuracy of the results produced by the mon$toring 6ystem. Other attempts which overcome the dead 6pace problems either 1) utilize expensive materials which, when incorporated into a disposable patient interface, make the interface very expensive for a one time use item, or 2) are sub~ect to blockage in short periods of time.
15The proliferation of respiratory gas monitoring technigues and the increased demand for breath-by-breath respiratory gas monitoring accentuate the need for a patient interfacing system which prevents moisture from reaching the detection portion of the gas analy6is systems.
- 20 Such a patient interface system should reduce or eliminate the frequency of occlusion or contamination of the gas transport sy~tem and detection portion of the gas analyzer.
This system should eliminate or reduce the risk of water vapor condensing within and clogging components of the system 6uch as the inline filter or the analyzer gas cell.
In addition, the patient interface system will desirably provide a barrier to prevent contamination in the form of secretions, condensed water, and particulates from entering the gas analyzer. It is preferred that such an interfacing device be a one time use item for hygienic reasons.
However, for economic reasons, a one time ~se item must also not be prohibitively expensive if is to be disposed of after a single use. The device of the present invention satisfies all of these requirements.
1 3 2 ~
~ummary of the Invention The present invention iB a method and apparatu6 for - interfacing a patient wlth gas analysls qulpment that monitors inspired and expired g~ses of a patlent. The invention utilizes a vaporization technique to inhibit or prevent mo~sture contained in the lnspired and xpired gases from obstructing the 6ample line or from reaching the ~ detector portion of the gas analyzer.
: 10 More 6pecifically, the invention relates to a method and 6ystem for interfacing a patient with a ga6 monitoring apparatus for analysis of a patient's re6piratory gases.
One embodiment of the invention includes a patient link which receives a sample of exhaled gases from the patient'6 airway. The patient lin~ comprises a tubing ~ection which is attached to a vaporization section. In a preferred embodiment, the vaporization section comprises a coil o' tubing formed by wrapping the tubing around a cylindrical spool in a plurality of proximate turns. The vaporization section is encased by a heated element which advantageously facilitates the vapor~zation of any condensed mo~sture which is typically contained in the respiratory gases. Attached to the output of the vapor~zation section is a hydrophobic filter which is permeable to the vaporized moisture but inhibits the passage of particulates and liquids. After pafising through the filter, the gase6 enter ~ separator section comprising a tubing material that is highly permeable to water vapor but has a very low permeability for respiratory gases, anesthetic ~gent gases and other gases being analyzed. The vaporized moisture which passes through the filter diffuses out of the ~ystem through the ~eparator section of water vapor per~eable tubing ~ub~tantially reducing the amount of moisture which enters the detector portion of the gas analyzer.
In one embodiment of the invention the invention 132511~
g comprises an apparatus for sampling the recpiratory gases of a patient through an airway circuit and delivering the gas sample to a gas analysi~ cell. A patient l$nk comprising a first length of tubinq connects to the airway circuit, receives the sample of respiratory gases and transports the sample toward the gas analysis cell. A
vaporization section receives the sample from the patient - link and vaporizes moisture contained in the cample. ~he vaporization section comprises a vaporization coil which comprises a spool having a cylindrical body portion. The body portion has a first end and a second end. A second length of tubing wraps around the body portion to form a coil having a plurality of proximate turns and a coil output. A disc-shaped filter having an input and an output is located at the second end of the cylindrical body wherein - the input to the filter connects to the output from the coil. trhe vaporization section i~ surrounded by a heating block having a means for heating the block to a " predetermined temperature and a chamber within the block for receiving the vaporization coil. A separator section having an input and an output is connected to the output of the disc filter, wherein the separator receives the gas sample from the filter and removes the water vapor portion from said gas sample to form a dried gas sample. ~he separator 6ection then delivers the dried gas sample to the gas analysis cell.
In one embodiment, the separator section comprises a water vapor permeable section. For example, the water vapor permeable section may be a section of Nafion tubing.
Another embodiment of the invention comprises an apparatus for sampling gases in the airway of a patient and delivering the sample to a gas monitor wherein the apparatus comprises: a patient lin~ for obtaining the gas sample from the patient airway and a vapor~zation section which receives the gas sample from the patient link and vaporizes condensed moisture contained in the sample before delivering the sample to the gas monitor.
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The invention further comprises a method of monitoring patient gases comprising the ~teps of: 1) extracting a ; sample portion of the gases from the patient; 2) vaporizing moi6ture contained in the ~ample portion; 3) r moving the vaporized moisture from the ~ample; and 4) delivering the sample to a monitoring apparatus.
The interfacing 6y6tem of the present invention has several significant advantages over alternate systems and methods. It reduces filter occlusion as a result of ~0 condensed water by utilizing vaporization technigues. It eliminates or reduces the risk of water vapor condensing inside the analyzer and contaminating the gas analy6is cell inside the instrument. Thus, the present invention overcomes many of the limitations of prior art devices in a device which offers superior performance in a cost - effective manner.
.
Brief Descri~tion of the Drawinas The preferred embodiment of the present invention is illustrated in and by the following drawings in which like reference numerals indicate like part~ and in which:
Figure 1 is a perspective view illustrating a patient interfacing system in accordance with the present - invention.
~ 25 Figure 2 is a cross section view illustrating details - of the vaporization 6ection of the invention.
Fiqure 3 i~ a cross section taken along the line 3-3 of Figure 2.
Figure 4 is a perspective view illustrating the patient link and vaporization coil of the invention.
Figure 5 is a plan view of the patient interfacing system of Figure 1.
Detailed Description of the Preferred Embodi~nt - 35 Figures 1, 4 and 5 ~how a patient interfacing system 10 which incorporates features of a preferred em~odiment of -: the present invention. The interfacing system 10 is a ., . j.
132~
device for connecting a patient via a patient circuit 11 with gas monitoring equipment 12 that ~oples and monitor~
inspired and expired ga~es of the patient. The patient interfacing ~y6tem 10 ~ay be u6ed with Do~t co~ercially available gas analyzer~ including but not limited to infrared (IR), polaragraph, ma~s ~pectrometer (NS), Raman ~pectrometer, etc. One cpecific ga~ analyzer with which the present invention is compatible i6 described in - United States Patent 4,784,486 issued 11/15/88 entitled "MULTI-CHANNEL MOLECULAR GAS ANALYSIS BY LASER ACTIVATED
RAMAN LIGHT", assigned to the assignee of the present invention.
The interface 6y6tem 10, as ~hown in Figures 1 and 5, compri6es a patient link 20, a vaporization ~ection 30 and n ~eparator section 40. The patient link 20 comprises a length of flexible tube or hose 42 having an input end 44 and an output end 46. The 1nput end 44 is connected to tbe patient's airway passage and the output end 46 i~ connected to an input of the vaporization section 30. An output of the vaporization section 30 is connected to an input of the ~eparator section 40 which has an output 47 connected to a gas input of the gas monitor 12.
In operation, the patient link 20 t~ps $nto the patient'6 airway passage and receives a 6ample of the patient's inspired ~nd expired gases. The tubing 42 delivers the ~ample to the vaporization section 30. Since the gas 6ample ~ay have a high moi6ture cDntent, it is possible that 60me of the moisture will condense before it reaches the vaporization ~ection 30. In ~ccordance with one embodiment of the invention, the vaporization 6ection 30 heats the gas ~ample to vaporize any condensed moi6ture contained in the ~ample. Thus, any conden6ed water which reaches the vaporization 6ection i6 vaporized while passinq through this section of the gas transport sy~tem. The air 6ample is then transported to the 6eparator 6ection where the water vapor portion of the 6ample is separated from the remaining gases comprisinq the 6ample. In this manner, ;, ~
. . .
12 132 ~
only substantially dry gas ~ampleQ are permitted to enter the gas analyzer. Typically, an air or vacuum pump, which is a component of the gas analyzer, pumps or draws air from the patient's airway through the interface ~y~tem 10 into the gas analyzer.
The patient link 20 compri6es a connector 48 at the input end 44. In one embodiment, the connector ~8 has a tube 50 extending therefrom which enter6 a facial orifice of the patient and terminates within the patient's airway at a point from which the sample of respiratory or anesthetic gases is to be extracted. The connector 48 may be attached to an endotracheal conduit, a nasal cannula, or a facial mask device to facilitate entrance into tbe patient' 5 airway via a tracheal incision, the nose and/or the mouth, respectively. A more detailed description of various means for entering the patient's airway may be found in U.S. Patent 4,485,822.
The flexible tube 42 delivers the samples of the inspired and expired gases to the vaporization 6ection 30 of the interface 10. The tubing 42 is preferably a cylindrical shape tubing made from a resilient ~nd flexible material. It is preferable that the tubing have a small diameter to facilitate continuous and rapid transportation of samples of inspired and expired gases to the monitoring instrument. The small diameter reduces the dead space volume of the interface 10, which as explained previously, gives the system a fast response time which is particularly advantageous in breath-by-breath analysis procedures. It is preferable that the inside diameter ~ID) of the tubing 42 be selected to be $n the range of from approx$mately 0.020 inches to approximately 0.060 $nches and the tubing - wall thickness be ~n the range of from approximately 0.010 inches to approximately 0.040 inches. This range of tubing dimensions will facilitate a gas flow rate in the range of ` 35 from approximately 30 ml/min to approximat~ly 400 ml/min.
In one embodiment, the ID of tubing section 42 is approximately 0.040 inches and the wall thickness is '`
;
132511~
approximately 0.032 inches. In thi6 embodiment, the length of the tubing ~ection 42 included between the input end 44 and the output end 46 is approximately ten feet. It will be understood, however, that these dimensions ~re by way of example only and that other dimen6ions could be elected for practicing the present invention.
In one embodiment, the vaporization 6ection 30 comprise6 a coil of flexible tubing 52 which i6 po6itioned within a heating block 54. The coil 52 and tube 42 may comprise a 6ingle length of tubing with the coil formed at the distal end of the length of tubing 42. The length of tubing comprising the coil i6 6elected to effectuate the desired degree of vaporization of moisture pas6ing through the coil. Several factor6 influence the 6election of this length including the temperature of the heating block, the distance 6eparating the ~urface of the coil from the inside walls of the heater, the amount of moisture in the sample, the flow rate of gas through the coil, the wall thickness of the tubing and the total exposed surface area of the coil. The length of tubing comprising the coil segment may vary from 2 inches to 50 inches depending upon the 6pecific application. In this embodiment, the length of the tubing 6ection which comprises the coil 52 is approximately two feet.
The coil 52 is formed by wrapping the tubing 42 around a 6pool 56 having a head portion 58. As shown ln Figure 2, the head 58 has an aperture 60 formed in the center through - which the tubing 42 is inserted. As best 6een in Figure 3, the spool 56 comprises two 6emi-circular wall 6ections 30 62,64. The 6emi-circular wall sections 62,64 of the 6pool 56 define two slots 66,68 which extend longitudinally along the length of the 6pool 56. The tubing 42 enters the interior region of the spool 56 through the aperture 60 in the head 58. The tubing 42 then exits the interior of the 35 6pool through one of the slots 66,68 and i~ wrapped around the exterior of the spool to form the coil 52. The end of the tubing then reenters the interior of the ~pool through ,~
:
-14- ~32~
one of the 610ts 66,68 and attaches to an input of a disc filter 70. In the embodiment 6hown in Figures 2, 4 and 5, the disc filter 70 al60 forms the ba6e of the cpool 56 opposite the head portion 58. In one ~mbodiment, the diameter of the vaporization coil 52 i~ approxlmately 1.15 inches.
The heating block 54, shown in Figure6 2, 3 and 5, comprises a main portion 72 and an extending portion 74 pro~ecting therefrom. ~he main portion 72 has an cylindrical opening 76 suitably shaped and sized to accommodate the vaporization coil 52. The extending portion 74 has a channel 78 extending therethrough for receiving a heater 80. The heating block S4 may be fabricated from any 6uitable thermally conductive material 6uch as aluminum or copper.
~ he cylindrical opening 76 has an interior wall 77 which completely surrounds the vaporization coil 52. This facil~tates a uniform transfer of heat from the heating block 54 to the coil 52. When the coil 52 is inserted within the opening 76, the coil 52 is placed in close proximity to the interior wall 77 so as to allow efSective heat transfer from the block 54 to the coils 52 so as to heat the gases flowing through the coil and vaporize any ,moisture contained therein. Typically, the ~uter exposed . 25 surface of the coil 52 is positioned 6uch that the distance between the exposed 6urface of the coil and the wall 77 of the heater is in the range of from approximately 0.010 inches to approximately 0.100 inches.
The heater 80 may comprise an electrically resistive heating rod or other device capable of 6upplying heat to the block 54. The heater 80 raises the temperature of the block 54 to a predetermined temperature sufficient to vaporize moisture travelling through the coil 52. The -~ heater 80 is regulated by a thermostat 82 ~ounted on the 35heater block 54 80 that it 6enses the temperature of the - block. The thermostat is ~elected to maintain the temperature of the block 54 at the predetermined ' 132~
temperature. One such thermostat which may be used is a bi-metallic switch which turns the heater on when the temperature of the block falls below a lower limit threshold and turns the heater off when the temperature of the block is above an upper limit threshold. The predetermined temperature of the block 54 is typically within the range of from approximately 37 C to approximately 75 C. In one embodiment, the thermostat 82 has a control temperature of approximately 50 C.
The cylindrical opening 76 of the heater block 78 terminates in a smaller concentric opening 84 in which is - positioned a female portion 85 of a two piece tubing connector. A male portion 86 of the two piece connector forms the output of the filter 70 which is connected to the output of the vaporization coil 52 and also forms the base of the vaporization coil. When the coil 52 is positioned within the opening 76 and the male and female connector portions 85,86 are joined together, the coil 52 is automatically aligned within the opening 76 of the heater block 54.
The filter 70 is disc-shaped and has a diameter in the range of from approximately 4 mm to approximately 50 mm.
The filter 70 has a large surface area as compared to its volume and a small pore size. For example, the pore size may range from approximately 0.2 microns to approximately 1.2 microns. This configuration limits penetration of the filter by non-gaseous components present in the sample, ` such as particulates or liquids. These non-gaseous components are trapped at the surface of the filter. Thus, ~,~ 30 the filter 70 prevents secretions from the patient and other liquids from being delivered to the monitoring -~ apparatus while allowing the gas sample to freely pass to the gas monitor. In view of it's function, it is . beneficial for the filter 70 to be constructed from ` 35 hydrophobic filter materials, such as PTFE (Gortex~) and ; hydrophobic grade acrylic copolymer membranes (Versapor~).
- The disc filter 70 has an output which is connected to the -16- ~32~
input of the separator section 40.
The 6eparator 6ection 40 comprise6 a cect$on of water vapor permeable tubing 88. Typically, the tubing 88 has a length in the range of from approximately 6 inches to approximately 48 inches, an inside diameter (ID) in the range of from approximately 0.020 inches to approximately 0.085 inches and a wall thicknes6 in the range of from about 0.004 inches to about 0.008 inches. In one embodiment of the present invention, the tubing 88 comprises a polymer that i6 highly permeable to water vapor but has a very low permeability for the respiratory and anesthetic gases being analyzed. Thus, water vapor rapidly diffuses out of the gas sample when the sample passes through the separator section 40. One commercially available product having these characteristics is a polymer which was developed by Du Pont scientists and is marketed in tubing form as Nafion tubing. In one embodiment, a section of Nafion tubing having a length of approximately 24 inches, an ID of approximately 0.040 inches and a wall thickness of approximately 0.006 inches is used. The Nafion tubing 88 is attached directly to the outflow side of the disc membrane filter 70, thus allowing a ma~ority of the water vapor contained in the ~ample and vaporized in the vaporization coil 52 to diffuse out of the gas transport sy6tem through the Nafion~ tubing before the ~ample reaches the gas analysis cell. The output end of .~ the tubing 88 is attached to the connector 47 which 'A connects to the gas analysis cell. In the configuration shown, the Nafion tubing 88 is near the end of the gas transport system and thus can be permanently attached to the gas analyzer at its input. In this position, the Nafion tubing 88 does not reguire cleaning and ~terilization after each patient use.
The system and processes described herein were developed primarily for use in prevsnting water contamination during the analysis of respiratory gases.
However, the invention may also be useful for other devices 132511~
and applications. While the above description compri6es an embodiment of the ~nvention as applied to the analysi6 of respiratory gases there are other applications whlch will be obvious to those skilled in the art.
The invention may be embodied in other epecific forms without departing from it6 ~pirit or ~ential characteristics. The described embodiment~ are to be considered in all re6pects only as illu6trative and not restrictive. The ~cope of the invention 16, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
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' :
. ., :
:~.
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METHOD". This patent di6closes a patient interface which relies on a disc-~haped hydrophobic filter to prevent fluids from entering the analyzer. This 6ystem overcomes the poor response time of most cold trap ~nd desiccator ystems by using a low dead 6pace volume disc filter. In 6uch an interface, however, in the event that the patient requires a humidifier, enough water can condense within the filter to occlude gas flow through the filter. In 60me cases, tbis can occur within 30 minute&, depending on the gas flow rate to the analyzer and the ambient temperature.
Not only i8 this inconvenient for the medical 6taff and patient, 6ince the filter must be changed freguently, but this can also result in a loss of vital medical information during the time period that the filter is being changed.
~. S. Patent No. 4,549,553 entitled ~APPARATUS AND
METHOD FOR USE IN A MEDICAL GAS SAMPLING SYSTEM", discloses an approach for providing a 6ample gas flow from ~n air tube to a patient undergoing automatic ventilation. The 132511~
air tube includes a gas diffusive membrane disposed in a wall of the air tube. The qas diffusive Dembrane may be made of water absorbing or water pa6sing materials to eliminate excess water from accumulating and bloc~ing the gas sample flow. In a preferred embodiment a non-wettable gas diffusive membrane is used to prevent or reduce water from entering the sample gas flow; otherwise, water caturates the membrane and water eventually pas~es through the membrane to enter the gas ~ample flow. By non-wettable it is meant that the membrane resist6 or cannot be - saturated with liguid and it6 curfaces resist or cannot be covered with liguid. A Teflon mesh membrane is a 6uitable non-wettable membrane for this application. Teflon i6 a registered trademark of E.I. Du Pont de Nemours & Company, Inc in Wilmington, Delaware. This approach, while perhaps ~ reducing the frequency of sample flow blockage, does - nothing to remove the moisture from the system and is 6till 6usceptible to occlusion in long term usage. AdditiGnally, the embodiment shown in Figure lA incorporates a large volume funnel 20 which increases the dead 6pace volume in the gas transport 6ystem and results in poor response time characteristics.
A more recent approach for preventinq water from condensing in the gas transport circuitry uses interface tubinq comprising a polymer that i6 highly permeable to water vapor, but simultaneously has a very low permeability for the respiratory and anesthetic gases being ~nalyzed.
One such polymer was developed by Du Pont scientists and is marketed in tubing form as Nafion tubing. Nafion is a registered trademark of E.I. Du Pont de Nemour6 & Company, Inc. in Wilmington, Delaware. By attaching the Nafion tubing directly to the patient breathing circuit near the connection to the patient, a ma~ority of the water vapor in the 6ample gases diffuses out before it arrives at the filter barrier. The disadvantage of this approach is the high cost of the Nafion~ tubing. A 6ection of Nafion~
tubing of 6ufficient length to remove the desired amount of 132~
water vapor is very expensive in relation to the cost of the other components comprising the patient interface.
Therefore, it is generally considered a reusable rather than a disposable gas samplinq line and, a~ uch, requires cleaning and sterilization between uses.
~ any of the attempts heretofore to remove liguids from patient interfaces introduce levels of dead ~pace into the - interfacing ~ystem which adversely affect the accuracy of the results produced by the mon$toring 6ystem. Other attempts which overcome the dead 6pace problems either 1) utilize expensive materials which, when incorporated into a disposable patient interface, make the interface very expensive for a one time use item, or 2) are sub~ect to blockage in short periods of time.
15The proliferation of respiratory gas monitoring technigues and the increased demand for breath-by-breath respiratory gas monitoring accentuate the need for a patient interfacing system which prevents moisture from reaching the detection portion of the gas analy6is systems.
- 20 Such a patient interface system should reduce or eliminate the frequency of occlusion or contamination of the gas transport sy~tem and detection portion of the gas analyzer.
This system should eliminate or reduce the risk of water vapor condensing within and clogging components of the system 6uch as the inline filter or the analyzer gas cell.
In addition, the patient interface system will desirably provide a barrier to prevent contamination in the form of secretions, condensed water, and particulates from entering the gas analyzer. It is preferred that such an interfacing device be a one time use item for hygienic reasons.
However, for economic reasons, a one time ~se item must also not be prohibitively expensive if is to be disposed of after a single use. The device of the present invention satisfies all of these requirements.
1 3 2 ~
~ummary of the Invention The present invention iB a method and apparatu6 for - interfacing a patient wlth gas analysls qulpment that monitors inspired and expired g~ses of a patlent. The invention utilizes a vaporization technique to inhibit or prevent mo~sture contained in the lnspired and xpired gases from obstructing the 6ample line or from reaching the ~ detector portion of the gas analyzer.
: 10 More 6pecifically, the invention relates to a method and 6ystem for interfacing a patient with a ga6 monitoring apparatus for analysis of a patient's re6piratory gases.
One embodiment of the invention includes a patient link which receives a sample of exhaled gases from the patient'6 airway. The patient lin~ comprises a tubing ~ection which is attached to a vaporization section. In a preferred embodiment, the vaporization section comprises a coil o' tubing formed by wrapping the tubing around a cylindrical spool in a plurality of proximate turns. The vaporization section is encased by a heated element which advantageously facilitates the vapor~zation of any condensed mo~sture which is typically contained in the respiratory gases. Attached to the output of the vapor~zation section is a hydrophobic filter which is permeable to the vaporized moisture but inhibits the passage of particulates and liquids. After pafising through the filter, the gase6 enter ~ separator section comprising a tubing material that is highly permeable to water vapor but has a very low permeability for respiratory gases, anesthetic ~gent gases and other gases being analyzed. The vaporized moisture which passes through the filter diffuses out of the ~ystem through the ~eparator section of water vapor per~eable tubing ~ub~tantially reducing the amount of moisture which enters the detector portion of the gas analyzer.
In one embodiment of the invention the invention 132511~
g comprises an apparatus for sampling the recpiratory gases of a patient through an airway circuit and delivering the gas sample to a gas analysi~ cell. A patient l$nk comprising a first length of tubinq connects to the airway circuit, receives the sample of respiratory gases and transports the sample toward the gas analysis cell. A
vaporization section receives the sample from the patient - link and vaporizes moisture contained in the cample. ~he vaporization section comprises a vaporization coil which comprises a spool having a cylindrical body portion. The body portion has a first end and a second end. A second length of tubing wraps around the body portion to form a coil having a plurality of proximate turns and a coil output. A disc-shaped filter having an input and an output is located at the second end of the cylindrical body wherein - the input to the filter connects to the output from the coil. trhe vaporization section i~ surrounded by a heating block having a means for heating the block to a " predetermined temperature and a chamber within the block for receiving the vaporization coil. A separator section having an input and an output is connected to the output of the disc filter, wherein the separator receives the gas sample from the filter and removes the water vapor portion from said gas sample to form a dried gas sample. ~he separator 6ection then delivers the dried gas sample to the gas analysis cell.
In one embodiment, the separator section comprises a water vapor permeable section. For example, the water vapor permeable section may be a section of Nafion tubing.
Another embodiment of the invention comprises an apparatus for sampling gases in the airway of a patient and delivering the sample to a gas monitor wherein the apparatus comprises: a patient lin~ for obtaining the gas sample from the patient airway and a vapor~zation section which receives the gas sample from the patient link and vaporizes condensed moisture contained in the sample before delivering the sample to the gas monitor.
132~
The invention further comprises a method of monitoring patient gases comprising the ~teps of: 1) extracting a ; sample portion of the gases from the patient; 2) vaporizing moi6ture contained in the ~ample portion; 3) r moving the vaporized moisture from the ~ample; and 4) delivering the sample to a monitoring apparatus.
The interfacing 6y6tem of the present invention has several significant advantages over alternate systems and methods. It reduces filter occlusion as a result of ~0 condensed water by utilizing vaporization technigues. It eliminates or reduces the risk of water vapor condensing inside the analyzer and contaminating the gas analy6is cell inside the instrument. Thus, the present invention overcomes many of the limitations of prior art devices in a device which offers superior performance in a cost - effective manner.
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Brief Descri~tion of the Drawinas The preferred embodiment of the present invention is illustrated in and by the following drawings in which like reference numerals indicate like part~ and in which:
Figure 1 is a perspective view illustrating a patient interfacing system in accordance with the present - invention.
~ 25 Figure 2 is a cross section view illustrating details - of the vaporization 6ection of the invention.
Fiqure 3 i~ a cross section taken along the line 3-3 of Figure 2.
Figure 4 is a perspective view illustrating the patient link and vaporization coil of the invention.
Figure 5 is a plan view of the patient interfacing system of Figure 1.
Detailed Description of the Preferred Embodi~nt - 35 Figures 1, 4 and 5 ~how a patient interfacing system 10 which incorporates features of a preferred em~odiment of -: the present invention. The interfacing system 10 is a ., . j.
132~
device for connecting a patient via a patient circuit 11 with gas monitoring equipment 12 that ~oples and monitor~
inspired and expired ga~es of the patient. The patient interfacing ~y6tem 10 ~ay be u6ed with Do~t co~ercially available gas analyzer~ including but not limited to infrared (IR), polaragraph, ma~s ~pectrometer (NS), Raman ~pectrometer, etc. One cpecific ga~ analyzer with which the present invention is compatible i6 described in - United States Patent 4,784,486 issued 11/15/88 entitled "MULTI-CHANNEL MOLECULAR GAS ANALYSIS BY LASER ACTIVATED
RAMAN LIGHT", assigned to the assignee of the present invention.
The interface 6y6tem 10, as ~hown in Figures 1 and 5, compri6es a patient link 20, a vaporization ~ection 30 and n ~eparator section 40. The patient link 20 comprises a length of flexible tube or hose 42 having an input end 44 and an output end 46. The 1nput end 44 is connected to tbe patient's airway passage and the output end 46 i~ connected to an input of the vaporization section 30. An output of the vaporization section 30 is connected to an input of the ~eparator section 40 which has an output 47 connected to a gas input of the gas monitor 12.
In operation, the patient link 20 t~ps $nto the patient'6 airway passage and receives a 6ample of the patient's inspired ~nd expired gases. The tubing 42 delivers the ~ample to the vaporization section 30. Since the gas 6ample ~ay have a high moi6ture cDntent, it is possible that 60me of the moisture will condense before it reaches the vaporization ~ection 30. In ~ccordance with one embodiment of the invention, the vaporization 6ection 30 heats the gas ~ample to vaporize any condensed moi6ture contained in the ~ample. Thus, any conden6ed water which reaches the vaporization 6ection i6 vaporized while passinq through this section of the gas transport sy~tem. The air 6ample is then transported to the 6eparator 6ection where the water vapor portion of the 6ample is separated from the remaining gases comprisinq the 6ample. In this manner, ;, ~
. . .
12 132 ~
only substantially dry gas ~ampleQ are permitted to enter the gas analyzer. Typically, an air or vacuum pump, which is a component of the gas analyzer, pumps or draws air from the patient's airway through the interface ~y~tem 10 into the gas analyzer.
The patient link 20 compri6es a connector 48 at the input end 44. In one embodiment, the connector ~8 has a tube 50 extending therefrom which enter6 a facial orifice of the patient and terminates within the patient's airway at a point from which the sample of respiratory or anesthetic gases is to be extracted. The connector 48 may be attached to an endotracheal conduit, a nasal cannula, or a facial mask device to facilitate entrance into tbe patient' 5 airway via a tracheal incision, the nose and/or the mouth, respectively. A more detailed description of various means for entering the patient's airway may be found in U.S. Patent 4,485,822.
The flexible tube 42 delivers the samples of the inspired and expired gases to the vaporization 6ection 30 of the interface 10. The tubing 42 is preferably a cylindrical shape tubing made from a resilient ~nd flexible material. It is preferable that the tubing have a small diameter to facilitate continuous and rapid transportation of samples of inspired and expired gases to the monitoring instrument. The small diameter reduces the dead space volume of the interface 10, which as explained previously, gives the system a fast response time which is particularly advantageous in breath-by-breath analysis procedures. It is preferable that the inside diameter ~ID) of the tubing 42 be selected to be $n the range of from approx$mately 0.020 inches to approximately 0.060 $nches and the tubing - wall thickness be ~n the range of from approximately 0.010 inches to approximately 0.040 inches. This range of tubing dimensions will facilitate a gas flow rate in the range of ` 35 from approximately 30 ml/min to approximat~ly 400 ml/min.
In one embodiment, the ID of tubing section 42 is approximately 0.040 inches and the wall thickness is '`
;
132511~
approximately 0.032 inches. In thi6 embodiment, the length of the tubing ~ection 42 included between the input end 44 and the output end 46 is approximately ten feet. It will be understood, however, that these dimensions ~re by way of example only and that other dimen6ions could be elected for practicing the present invention.
In one embodiment, the vaporization 6ection 30 comprise6 a coil of flexible tubing 52 which i6 po6itioned within a heating block 54. The coil 52 and tube 42 may comprise a 6ingle length of tubing with the coil formed at the distal end of the length of tubing 42. The length of tubing comprising the coil i6 6elected to effectuate the desired degree of vaporization of moisture pas6ing through the coil. Several factor6 influence the 6election of this length including the temperature of the heating block, the distance 6eparating the ~urface of the coil from the inside walls of the heater, the amount of moisture in the sample, the flow rate of gas through the coil, the wall thickness of the tubing and the total exposed surface area of the coil. The length of tubing comprising the coil segment may vary from 2 inches to 50 inches depending upon the 6pecific application. In this embodiment, the length of the tubing 6ection which comprises the coil 52 is approximately two feet.
The coil 52 is formed by wrapping the tubing 42 around a 6pool 56 having a head portion 58. As shown ln Figure 2, the head 58 has an aperture 60 formed in the center through - which the tubing 42 is inserted. As best 6een in Figure 3, the spool 56 comprises two 6emi-circular wall 6ections 30 62,64. The 6emi-circular wall sections 62,64 of the 6pool 56 define two slots 66,68 which extend longitudinally along the length of the 6pool 56. The tubing 42 enters the interior region of the spool 56 through the aperture 60 in the head 58. The tubing 42 then exits the interior of the 35 6pool through one of the slots 66,68 and i~ wrapped around the exterior of the spool to form the coil 52. The end of the tubing then reenters the interior of the ~pool through ,~
:
-14- ~32~
one of the 610ts 66,68 and attaches to an input of a disc filter 70. In the embodiment 6hown in Figures 2, 4 and 5, the disc filter 70 al60 forms the ba6e of the cpool 56 opposite the head portion 58. In one ~mbodiment, the diameter of the vaporization coil 52 i~ approxlmately 1.15 inches.
The heating block 54, shown in Figure6 2, 3 and 5, comprises a main portion 72 and an extending portion 74 pro~ecting therefrom. ~he main portion 72 has an cylindrical opening 76 suitably shaped and sized to accommodate the vaporization coil 52. The extending portion 74 has a channel 78 extending therethrough for receiving a heater 80. The heating block S4 may be fabricated from any 6uitable thermally conductive material 6uch as aluminum or copper.
~ he cylindrical opening 76 has an interior wall 77 which completely surrounds the vaporization coil 52. This facil~tates a uniform transfer of heat from the heating block 54 to the coil 52. When the coil 52 is inserted within the opening 76, the coil 52 is placed in close proximity to the interior wall 77 so as to allow efSective heat transfer from the block 54 to the coils 52 so as to heat the gases flowing through the coil and vaporize any ,moisture contained therein. Typically, the ~uter exposed . 25 surface of the coil 52 is positioned 6uch that the distance between the exposed 6urface of the coil and the wall 77 of the heater is in the range of from approximately 0.010 inches to approximately 0.100 inches.
The heater 80 may comprise an electrically resistive heating rod or other device capable of 6upplying heat to the block 54. The heater 80 raises the temperature of the block 54 to a predetermined temperature sufficient to vaporize moisture travelling through the coil 52. The -~ heater 80 is regulated by a thermostat 82 ~ounted on the 35heater block 54 80 that it 6enses the temperature of the - block. The thermostat is ~elected to maintain the temperature of the block 54 at the predetermined ' 132~
temperature. One such thermostat which may be used is a bi-metallic switch which turns the heater on when the temperature of the block falls below a lower limit threshold and turns the heater off when the temperature of the block is above an upper limit threshold. The predetermined temperature of the block 54 is typically within the range of from approximately 37 C to approximately 75 C. In one embodiment, the thermostat 82 has a control temperature of approximately 50 C.
The cylindrical opening 76 of the heater block 78 terminates in a smaller concentric opening 84 in which is - positioned a female portion 85 of a two piece tubing connector. A male portion 86 of the two piece connector forms the output of the filter 70 which is connected to the output of the vaporization coil 52 and also forms the base of the vaporization coil. When the coil 52 is positioned within the opening 76 and the male and female connector portions 85,86 are joined together, the coil 52 is automatically aligned within the opening 76 of the heater block 54.
The filter 70 is disc-shaped and has a diameter in the range of from approximately 4 mm to approximately 50 mm.
The filter 70 has a large surface area as compared to its volume and a small pore size. For example, the pore size may range from approximately 0.2 microns to approximately 1.2 microns. This configuration limits penetration of the filter by non-gaseous components present in the sample, ` such as particulates or liquids. These non-gaseous components are trapped at the surface of the filter. Thus, ~,~ 30 the filter 70 prevents secretions from the patient and other liquids from being delivered to the monitoring -~ apparatus while allowing the gas sample to freely pass to the gas monitor. In view of it's function, it is . beneficial for the filter 70 to be constructed from ` 35 hydrophobic filter materials, such as PTFE (Gortex~) and ; hydrophobic grade acrylic copolymer membranes (Versapor~).
- The disc filter 70 has an output which is connected to the -16- ~32~
input of the separator section 40.
The 6eparator 6ection 40 comprise6 a cect$on of water vapor permeable tubing 88. Typically, the tubing 88 has a length in the range of from approximately 6 inches to approximately 48 inches, an inside diameter (ID) in the range of from approximately 0.020 inches to approximately 0.085 inches and a wall thicknes6 in the range of from about 0.004 inches to about 0.008 inches. In one embodiment of the present invention, the tubing 88 comprises a polymer that i6 highly permeable to water vapor but has a very low permeability for the respiratory and anesthetic gases being analyzed. Thus, water vapor rapidly diffuses out of the gas sample when the sample passes through the separator section 40. One commercially available product having these characteristics is a polymer which was developed by Du Pont scientists and is marketed in tubing form as Nafion tubing. In one embodiment, a section of Nafion tubing having a length of approximately 24 inches, an ID of approximately 0.040 inches and a wall thickness of approximately 0.006 inches is used. The Nafion tubing 88 is attached directly to the outflow side of the disc membrane filter 70, thus allowing a ma~ority of the water vapor contained in the ~ample and vaporized in the vaporization coil 52 to diffuse out of the gas transport sy6tem through the Nafion~ tubing before the ~ample reaches the gas analysis cell. The output end of .~ the tubing 88 is attached to the connector 47 which 'A connects to the gas analysis cell. In the configuration shown, the Nafion tubing 88 is near the end of the gas transport system and thus can be permanently attached to the gas analyzer at its input. In this position, the Nafion tubing 88 does not reguire cleaning and ~terilization after each patient use.
The system and processes described herein were developed primarily for use in prevsnting water contamination during the analysis of respiratory gases.
However, the invention may also be useful for other devices 132511~
and applications. While the above description compri6es an embodiment of the ~nvention as applied to the analysi6 of respiratory gases there are other applications whlch will be obvious to those skilled in the art.
The invention may be embodied in other epecific forms without departing from it6 ~pirit or ~ential characteristics. The described embodiment~ are to be considered in all re6pects only as illu6trative and not restrictive. The ~cope of the invention 16, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
..
.'~
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. ., :
:~.
~ .
Claims (17)
1. An apparatus for sampling the respiratory gases of a patient through an airway circuit and delivering same to a gas analysis cell, said apparatus comprising:
a patient link comprising a first length of tubing which connects to said airway circuit, receives said sample of said respiratory gases and transports said sample toward said gas analysis cell;
a vaporization section which receives said sample from said patient link and vaporizes moisture contained in said sample, said vaporization section comprising:
a vaporization coil comprising a spool having a cylindrical body portion, said body portion having a first end and a second end, wherein a second length of tubing wraps around said body portion to form a coil having a plurality of proximate turns and a coil output;
a membrane filter having an input and an output, said filter located at said second end of said cylindrical body wherein said input to said filter connects to said output from said coil;
and a heated segment having a means for heating said segment to a predetermined temperature and a chamber within said segment for receiving said vaporization coil;
and a separator section having an input and an output, said separator input connected to said output of said membrane filter, wherein said separator receives said gas sample from said filter, removes said water vapor portion from said gas sample to form a dried gas sample and delivers said dried gas sample to said gas analysis cell.
a patient link comprising a first length of tubing which connects to said airway circuit, receives said sample of said respiratory gases and transports said sample toward said gas analysis cell;
a vaporization section which receives said sample from said patient link and vaporizes moisture contained in said sample, said vaporization section comprising:
a vaporization coil comprising a spool having a cylindrical body portion, said body portion having a first end and a second end, wherein a second length of tubing wraps around said body portion to form a coil having a plurality of proximate turns and a coil output;
a membrane filter having an input and an output, said filter located at said second end of said cylindrical body wherein said input to said filter connects to said output from said coil;
and a heated segment having a means for heating said segment to a predetermined temperature and a chamber within said segment for receiving said vaporization coil;
and a separator section having an input and an output, said separator input connected to said output of said membrane filter, wherein said separator receives said gas sample from said filter, removes said water vapor portion from said gas sample to form a dried gas sample and delivers said dried gas sample to said gas analysis cell.
2. An apparatus as defined in Claim 1 wherein said means for heating comprises an electrically resistive heating element and a thermostat to control the temperature of said heating block.
3. An apparatus as defined in Claim 1 wherein said separator section comprises a water vapor permeable section.
4. An apparatus as defined in Claim 3 wherein said water vapor permeable section comprises a section of Nafion? tubing.
5. An apparatus for sampling gases of a patient and delivering same to a gas monitor, said apparatus comprising:
a patient link having a patient link input end and a patient link output end, said patient link input end having means to receive a sample of gases;
a vaporization section for vaporizing moisture contained in said sample of gases, said vaporization section having a vaporization section input and a vaporization section output, said vaporization section input coupled to said patient link output end, said vaporization section having means to receive said gas sample from said patient link and to vaporize any moisture contained in said sample, wherein said vaporization section further comprises a filter having a filter input and a filter output, said filter input coupled to said vaporization section output, for receiving said sample from said vaporization section, said filter having means to transmit gaseous components of said sample and to block particulate and liquid components of said sample; and a separator section having a separator input and a separator output, said separator input coupled to said filter output and said separator output having means for delivering said sample to a gas analysis cell, said separator section further comprising a water vapor permeable section positioned intermediate said separator input and said separator output, wherein said separator section is for receiving said sample and vaporized moisture therein from said vaporization section and removing said vaporized moisture from said sample such that said sample which exits said separator output contains less vaporized moisture than when it entered said separator input.
a patient link having a patient link input end and a patient link output end, said patient link input end having means to receive a sample of gases;
a vaporization section for vaporizing moisture contained in said sample of gases, said vaporization section having a vaporization section input and a vaporization section output, said vaporization section input coupled to said patient link output end, said vaporization section having means to receive said gas sample from said patient link and to vaporize any moisture contained in said sample, wherein said vaporization section further comprises a filter having a filter input and a filter output, said filter input coupled to said vaporization section output, for receiving said sample from said vaporization section, said filter having means to transmit gaseous components of said sample and to block particulate and liquid components of said sample; and a separator section having a separator input and a separator output, said separator input coupled to said filter output and said separator output having means for delivering said sample to a gas analysis cell, said separator section further comprising a water vapor permeable section positioned intermediate said separator input and said separator output, wherein said separator section is for receiving said sample and vaporized moisture therein from said vaporization section and removing said vaporized moisture from said sample such that said sample which exits said separator output contains less vaporized moisture than when it entered said separator input.
6. An apparatus as defined in Claim 5 wherein said water vapor permeable section comprises a section of Nafion? tubing.
7. An apparatus as defined in Claim 5 further comprising a heater for vaporizing condensed moisture within said vaporization section.
8. A method of providing a sample of a patient's inspired respiratory gases to a monitoring apparatus comprising the steps of:
extracting a sample portion of said respiratory gases from said patient;
vaporizing moisture contained in said sample portion in a vaporization section, said vaporization section having a vaporization section input end and a vaporization section output end, said vaporization section input end having means to receive said sample portion;
filtering said sample portion through a filter having a filter input and a filter output, wherein said filter input connects to said vaporization section output end;
removing said vaporized moisture from said sample portion, said step of removing said vaporized moisture further comprising the steps of:
passing said sample portion through a water vapor permeable section having an input end and an output end, wherein said water vapor permeable section input end connects to said filter output;
and extracting said vaporized moisture from said water vapor permeable section between said water vapor permeable section input end and said water vapor permeable section output end such that said sample portion which exits through said water vapor permeable section output end contains less vaporized moisture upon exiting said water vapor permeable section than it contained when it entered said water vapor permeable section; and delivering said sample portion to said monitoring apparatus.
extracting a sample portion of said respiratory gases from said patient;
vaporizing moisture contained in said sample portion in a vaporization section, said vaporization section having a vaporization section input end and a vaporization section output end, said vaporization section input end having means to receive said sample portion;
filtering said sample portion through a filter having a filter input and a filter output, wherein said filter input connects to said vaporization section output end;
removing said vaporized moisture from said sample portion, said step of removing said vaporized moisture further comprising the steps of:
passing said sample portion through a water vapor permeable section having an input end and an output end, wherein said water vapor permeable section input end connects to said filter output;
and extracting said vaporized moisture from said water vapor permeable section between said water vapor permeable section input end and said water vapor permeable section output end such that said sample portion which exits through said water vapor permeable section output end contains less vaporized moisture upon exiting said water vapor permeable section than it contained when it entered said water vapor permeable section; and delivering said sample portion to said monitoring apparatus.
9. A method as defined in Claim 8, wherein said step of vaporizing comprises heating said sample to a predetermined temperature for vaporizing said moisture in said sample portion.
10. A method as defined in Claim 8, wherein said water vapor permeable section comprises a section of Nafion° tubing.
11. An apparatus for sampling gases in the airway of a patient and delivering gas samples to a monitoring device, said apparatus comprising:
a first portion wherein said first portion comprises:
a patient link which receives said gas samples from said patient airway;
a vaporization section wherein moisture contained in said sample received from said patient link is vaporized; and a filter which removes nongaseous components of said sample;
and a second portion wherein said second portion comprises:
a heating section which surrounds said vaporization section; and a water vapor permeable section for selectively transmitting vaporized moisture.
a first portion wherein said first portion comprises:
a patient link which receives said gas samples from said patient airway;
a vaporization section wherein moisture contained in said sample received from said patient link is vaporized; and a filter which removes nongaseous components of said sample;
and a second portion wherein said second portion comprises:
a heating section which surrounds said vaporization section; and a water vapor permeable section for selectively transmitting vaporized moisture.
12. An apparatus as defined in Claim 11, wherein said water vapor permeable section comprises a section of Nafion? tubing.
-21a-
-21a-
13. An apparatus as defined in Claim 11, wherein said first portion comprises materials making it economical to dedicate said first portion use to a single patient and to dispose of said first portion after each use.
14. An apparatus as defined in Claim 11, wherein said heating section comprises a thermally conductive block and an electrical heating element, said heating element having means to maintain the temperature of said block at a predetermined temperature.
15. A method of sampling the inspired and expired gases of a patient and delivering the same to a monitoring apparatus comprising the steps of:
extracting a sample portion of said gases from said patient;
vaporizing condensed moisture contained in said sample portion by heating said sample portion to a predetermined temperature in a vaporization section, said vaporization section having a vaporization section input end and a vaporization section output end, said vaporization section input end having means to receive said sample portion;
filtering said sample portion through a filter having a filter input and a filter output, wherein said filter input connects to said vaporization section output end;
removing said vaporized moisture from said sample portion, said step of removing said vaporized moisture further comprising the steps of:
passing said sample portion through a water vapor permeable section having an input end and an output end, wherein said water vapor permeable section input end connects to said filter output;
and expelling said vaporized moisture from said water vapor permeable section between said water vapor permeable section input end and said water vapor permeable section output end such that said -21b-sample portion contains less vaporized moisture upon exiting said output end than it contained upon entering said input end; and delivering said sample portion to the monitoring apparatus.
extracting a sample portion of said gases from said patient;
vaporizing condensed moisture contained in said sample portion by heating said sample portion to a predetermined temperature in a vaporization section, said vaporization section having a vaporization section input end and a vaporization section output end, said vaporization section input end having means to receive said sample portion;
filtering said sample portion through a filter having a filter input and a filter output, wherein said filter input connects to said vaporization section output end;
removing said vaporized moisture from said sample portion, said step of removing said vaporized moisture further comprising the steps of:
passing said sample portion through a water vapor permeable section having an input end and an output end, wherein said water vapor permeable section input end connects to said filter output;
and expelling said vaporized moisture from said water vapor permeable section between said water vapor permeable section input end and said water vapor permeable section output end such that said -21b-sample portion contains less vaporized moisture upon exiting said output end than it contained upon entering said input end; and delivering said sample portion to the monitoring apparatus.
16. A method as defined in Claim 15, wherein said water vapor permeable section comprises a section of Nafion? tubing.
17. An apparatus for transporting a gas sample and removing moisture contained in the gas sample comprising:
a link section having means to receive a sample portion of a gas from a gas source;
a vaporization section, connected to said link section, said vaporization section having means to receive said sample portion from said link section and to vaporize moisture contained in said sample portion;
a filter for removing nongaseous components in said sample portion, said filter having a filter input and a filter output, said filter input coupled to said vaporization section to receive said sample portion from said vaporization section; and a separator section, connected to said filter output and having means to receive said sample portion, including any vaporized moisture, from said filter said separator section further having means to remove said vaporized moisture from said sample portion, said separator section further comprising:
a water vapor permeable section having an input end and an output end wherein said water vapor permeable section input end is coupled to said filter output to receive said sample portion from said filter, said water vapor permeable section having means to expel said vaporized moisture between said water vapor permeable section input end and said water vapor permeable section output end as said sample portion traverses said water vapor permeable section such -21c-that said sample portion which exits said water vapor permeable section output end contains less vaporized moisture than when it entered said water vapor permeable section input end.
a link section having means to receive a sample portion of a gas from a gas source;
a vaporization section, connected to said link section, said vaporization section having means to receive said sample portion from said link section and to vaporize moisture contained in said sample portion;
a filter for removing nongaseous components in said sample portion, said filter having a filter input and a filter output, said filter input coupled to said vaporization section to receive said sample portion from said vaporization section; and a separator section, connected to said filter output and having means to receive said sample portion, including any vaporized moisture, from said filter said separator section further having means to remove said vaporized moisture from said sample portion, said separator section further comprising:
a water vapor permeable section having an input end and an output end wherein said water vapor permeable section input end is coupled to said filter output to receive said sample portion from said filter, said water vapor permeable section having means to expel said vaporized moisture between said water vapor permeable section input end and said water vapor permeable section output end as said sample portion traverses said water vapor permeable section such -21c-that said sample portion which exits said water vapor permeable section output end contains less vaporized moisture than when it entered said water vapor permeable section input end.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19672588A | 1988-05-20 | 1988-05-20 | |
| US196,725 | 1988-05-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1325115C true CA1325115C (en) | 1993-12-14 |
Family
ID=22726599
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000600193A Expired - Fee Related CA1325115C (en) | 1988-05-20 | 1989-05-19 | Patient interfacing system and method to prevent water contamination |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0418267A4 (en) |
| JP (1) | JPH03504206A (en) |
| KR (1) | KR900701352A (en) |
| AU (1) | AU3571789A (en) |
| CA (1) | CA1325115C (en) |
| WO (1) | WO1989011245A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9021769D0 (en) * | 1990-10-06 | 1990-11-21 | Lion Tech Ltd | A mouthpiece |
| EP0577053A1 (en) * | 1992-06-30 | 1994-01-05 | Hideo Ueda | Expired gas sampling method and expired gas collecting tube |
| US20080027344A1 (en) * | 2006-07-27 | 2008-01-31 | Ric Investments, Llc | Modular sidestream gas sampling assembly |
| US20150343163A1 (en) * | 2014-06-02 | 2015-12-03 | Oridion Medical 1987 Ltd. | Breath sampling tube and device |
| EP3548129B1 (en) * | 2016-12-05 | 2022-03-23 | Servei Central d'Anestesiologia SLP | Devices for sampling exhaled air |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3507146A (en) * | 1968-02-09 | 1970-04-21 | Webb James E | Method and system for respiration analysis |
| US3649199A (en) * | 1970-03-26 | 1972-03-14 | Varian Associates | Method for detecting trace quantities of an organic drug material in a living animal |
| US4167667A (en) * | 1978-06-12 | 1979-09-11 | The Perkin-Elmer Corporation | Respiratory gas moisture separator system for mass spectrometer monitoring systems |
| US4425804A (en) * | 1981-10-29 | 1984-01-17 | The Perkin-Elmer Corp. | Ultrasonic air flow transducer for high humidity environments |
| US4549553A (en) * | 1983-11-07 | 1985-10-29 | Spacelabs, Inc. | Apparatus and method for use in a medical gas sampling system |
| US4727871A (en) * | 1985-10-28 | 1988-03-01 | Infrasonics, Inc. | Ventilator exhalation system |
-
1989
- 1989-05-09 AU AU35717/89A patent/AU3571789A/en not_active Abandoned
- 1989-05-09 WO PCT/US1989/001974 patent/WO1989011245A1/en not_active Ceased
- 1989-05-09 EP EP19890905879 patent/EP0418267A4/en not_active Withdrawn
- 1989-05-09 KR KR1019900700104A patent/KR900701352A/en not_active Withdrawn
- 1989-05-09 JP JP1506001A patent/JPH03504206A/en active Pending
- 1989-05-19 CA CA000600193A patent/CA1325115C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03504206A (en) | 1991-09-19 |
| AU3571789A (en) | 1989-12-12 |
| EP0418267A4 (en) | 1991-08-07 |
| KR900701352A (en) | 1990-12-01 |
| WO1989011245A1 (en) | 1989-11-30 |
| EP0418267A1 (en) | 1991-03-27 |
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