A novel paediatric anaesthetic breathing system

Introduction:  This paper describes a lightweight, valveless, coaxial anaesthetic breathing system which enables the convenient scavenging of exhaust/waste anaesthetic gases in theatre. It is essentially a modification of the Jackson-Rees T-piece system,[1] which utilises a specially designed reservoir bag and coaxial tubing to conduct waste anaesthetic gases to an active scavenging system sited on the anaesthetic machine.

Background:  In the conventional Jackson-Rees system, a length of anaesthetic tubing delivers the anaesthetic gas mixture to a T-junction sited close to the patient's mouth. A second arm of the T acts as patient connector while a third connects to a reservoir tube which conducts a mixture of fresh and expired gases to an opened tailed reservoir bag, from which the gases are vented to the operating theatre environment. Epidemiological studies suggest that exposure to these gases may adversely affect the health of theatre staff [2] and this problem has recently been the subject of a campaign by the National Association of Theatre Nurses. Successful attempts to scavenge these gases have mainly involved the introduction of an expiratory valve into the Jackson Rees system, which makes the system bulky and less convenient to use. The proposed system is shown in Figure 1.

Results and Conclusions:  In preliminary bench tests, a professionally made prototype of the proposed system was found to impose about the same degree of expiratory resistance as a Bain system [3] with a fully opened expiratory valve, which was considered acceptable. The system was also rated highly when assessed by a sample of consultant anaesthetists performing manual ventilation on a dummy lung. While the system's primary application will be in paediatric anaesthesia, it could also find application as an induction system for adult anaesthesia.

• (1)

[   Diagram of proposed breathing system. The inner tube arrangement is similar to that of a conventional Jackson-Rees T-piece system (4,2,5). However, in place of the open-tailed reservoir bag of the latter, the new system has a custom made bag (6) which incorporates an outer tube (8) to collect the waste anaesthetic gases via a vent situated between the outer tube and the tail section of the reservoir bag (9). This tube conducts the waste gases into the annular space between the tubes 4, 5 and 10, 11, from where they are ultimately discharged into an active scavenging system via port 13. ]