GB2348607A

GB2348607A - A cuff pressure controller for the laryngeal masks and tracheal tubes

Info

Publication number: GB2348607A
Application number: GB9907876A
Authority: GB
Inventors: Mohamed Osman Abdelatti
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-08
Filing date: 1999-04-08
Publication date: 2000-10-11
Anticipated expiration: 2019-04-08
Also published as: GB2348607B; GB9907876D0

Abstract

A cuff pressure controller for trachea tubes and the laryngeal masks, consists of a modified 10 ml plastic syringe 4. The plunger of the syringe was replaced with a metal (screw) bolt 3. The bung 5 of the original plunger was fixed to one end of the metal bolt. A flat washer and gland nut 2 were screwed over the metal bolt so that the resulting plunger can be rotated forward and backward inside the syringe barrel in a controlled fashion. Rotation of plunger anti-clockwise moves the plunger backward creating a space (external cuff reservoir) in the syringe where excess air from an over-inflated cuff can be vented to control its pressure. Monitoring and control of the pressure may be achieved using a pressure gauge 9 in line with the cuff and the modified syringe.

Description

A cuff pressure controller for tracheal tubes and the laryngeal masks This invention relates to a device which controls the cuff pressure of tracheal tubes and the laryngeal masks during their use in anaesthetic practice.

Laryngeal masks and tracheal tubes (figure 1 and 2) are vital equipment for maintaining the patient's airway and breathing during anaesthesia and surgery. They have common structural features consisting of a cuff (ballon) 1 at or near the tip, a narrow tube (the pilot tube) 2 connected to the cuff and a pilot tube port 3. The tracheal tube is normally introduced into the trachea (wind pipe) and the laryngeal mask into the pharynx. The cuff has to be inflated with air using a syringe to secure the tracheal tube in the trachea, inorder to maintain a clear airway during breathing and prevent any material such as vomit from entering into the lungs. Inflation of the cuff of the laryngeal mask similarly secures it in the pharynx to maintain a clear airway during breathing. Normally, an appropriate amount of air is used to inflate the cuff so that the resulting cuff pressure does not damage the trachea and pharyngal structures.

However, during anaesthesia, nitrous oxide (an anaesthetic gas) diffuses into the air-filled cuff and the cuff pressure rises. Excessive cuff pressure exerted on the trachea and vital structures in the pharynx causes several complications including sore throat, damage to the trachea and to various structures in the pharynx such as the vocal cords, nerves and arteries.

To prevent these complications it has been recommended that the cuff pressure of tracheal tubes should not exceed 30 cm H20 and that of the laryngeal masks should be maintained close to 60 cm H20 Various devices are currently available for control of the cuff pressure of tracheal tubes but they are not routinely used in clinical practice largely, because they are either unreliable, large in size and or suffer various disadvantages including expense, complexity and a need for external gas supply or electricity. As far as the laryngeal mask is concerned there is as yet no device currently available for the control of its cuff pressure.

The present invention is concerned with solving the problem of monitoring and controlling the cuff pressure of tracheal tubes and the laryngeal masks in order to reduce the risk of tracheal and pharyngal complications particularly during prolonge anaesthesia and surgery.

It consist of a plastic syringe. Its plunger (piston) has been modified so that it can be screwed inside the syringe barrel, backward to remove air from an over-distended cuff connected to it. An aneroid pressure gauge was connected to the device as a means of monitoring the changes in cuff pressure.

A specific embodiment of the device will now be described by way of example with reference to the accompanying drawings in which.

Figure 1 shows a tracheal tube.

Figure 2 shows a laryngeal mask airway.

Figure 3. shows the invented device.

Figure 4. shows the invented device with the pressure gauge built onto the syringe nozzle to make the device more compact and reduce its size. According to the present invention there is provided a cuff pressure monitor and controller for tracheal tubes and the laryngeal masks (Figure 3 and 4). It consists of an ordinary 10 ml plastic syringe 4. Its piston (plunger) was removed and replace with a light metal (screw) bolt 3. A flat washer and gland nut 2 were screwed over the screw bolt. A rubber bung 5 detached from the original piston was fixed to one end of the bolt and a plastic knob (the control knob) 1 to the other end. The gland nut was tightened over the flat washer to seal the syringe end and to allow the modified plunger to be screwed, backward and forward, in the syringe barrel on rotation of the control knob. The complete device (modified syringe) was connected, via a small plastic tube 8, to a small aneroid pressure gauge 9 for monitoring the cuff pressure. A 3-way tap 6 was used to link the modified syringe and the pressure gauge to the pilot tube. A 100 cm long extension tubing 7 was connected to the syringe nozzle via the 3-way tap to allow monitoring and adjustment of the cuff pressure at a distance from the patient.

Referring to figure 3 and 4, rotation of the control knob anti-clockwise 11 moves the screw plunger backward and clockwise 12 rotation moves it forward. When the plunger moves backward it creates an external reservoir continuous with the volume of air in the cuff. Using the control knob, the capacity of this reservoir can be varied in a controlled fashion to adjust the cuff volume and pressure (by adding or removing very small volumes of air).

The device is designed so that adjustment (tuning) of the cuff volume and pressure-up or down-can be accomplished with precision to the nearest ml of air and or a cm of water pressure. To use the device, after the tracheal tube is inserted into the trachea and its cuff inflated : 1. Connect the pilot tube directly to the device or via the extension tubing.

2. Read the cuff pressure recorded by the aneroid gauge. If it is high, 3. Rotate the control knob anti-clockwise to adjust the cuff pressure.

4. Repeat step 2 and 3 every 15 to 30 minutes during anaesthesia.

5. Follow the same steps when using the laryngeal mask airway.

6. Use the extension tubing for continuous monitoring and adjusting the cuff pressure away from the patient.

Claims

CLAIMS 1 A cuff pressure controller for tracheal tubes and the laryngeal masks consisting of a 10 ml plastic syringe, a modified (screw bolt) piston, means for systematic and accurate withdrawal of excess air from an over-inflated tracheal tube or a laryngeal mask cuff.
2. A cuff pressure controller for tracheal tubes and the laryngeal masks as claimed in 1 wherein rotation means of the screw plunger forward and backward inside the syringe barrel in order to withdraw or add air to the cuff was achieved using a gland nut to stabilise the plunger and allow its rotation using a plastic control knob operated with twisting movement of the fingers.
3. A cuff pressure controller for tracheal tubes and the laryngeal masks as claimed in 1 or 2 wherein a cuff pressure monitoring means is provided with an aneroid pressure gauge connected to the syringe nozzle via a narrow tube.
4. A cuff pressure controller for tracheal tubes and the laryngeal masks as claimed in 1 or 2 or 3 wherein connecting means of the syringe nozzle to the aneroid pressure gauge and the cuff consisting of a 3-way tap.
5. A cuff pressure controller for tracheal tubes and the laryngeal masks as claimed in any preceding claim wherein monitoring of the cuff pressure at a distance from the patient can be achieved via a 100 cm long plastic tubing connected to the device and the cuff via a 3-way tap.
6. A cuff pressure controller for tracheal tubes and the laryngeal masks substantially as described herein with reference to Figure 3 and 4 of the accompanying drawings.