The Triservice Anaesthetic Apparatus – an alternative configuration

Configuration of draw‐over anaesthetic breathing system

“…We read with interest the comments by Henning regarding the positioning of the self‐inflating bag in the draw‐over breathing system [1]. Henning suggested that there would be a reduction in tidal volume delivered if the self‐inflating bag was positioned downstream of the ventilator during intermittent positive pressure ventilation (IPPV).…”

Configuration of draw‐over anaesthetic breathing system

“…Lieutenant Colonel Henning suggests that the breathing system of the Triservice Anaesthetic Apparatus should be reconfigured so that the self‐inflating bag is removed from between the patient non‐rebreathing valve and the vaporiser and inserted into the gas intake of the vaporiser (Fig. 1) [1]. Whilst I agree with him that anything that simplifies use and limits the number of connections and disconnections is desirable and should reduce the likelihood of errors, may I introduce a note of caution?…”

Configuration of drawover anaesthetic breathing systems

“…Recent communications about drawover anaesthetic systems have suggested that it is acceptable to position the selfinflating bag so as to pushover the OMV (Penlon, Abingdon, UK) [1] and to leave the self-inflating bag in the system when a mechanical ventilator is connected to the open end [2]. We would like to add to the concerns expressed by Houghton [3].…”

“…If the self-inflating bag is positioned proximal to the OMV vaporiser as suggested by Henning [1], with the outlet of the bag facing the vaporiser, there is no valve between the bag and the vaporiser as the valve is on the inlet of the bag. As the self-inflating bag inflates it draws most gas from its inlet, but some may be drawn in a retrograde fashion back into the bag through the outlet.…”

“…I was interested to learn from Lee and colleagues' trial [1] that the incidence of postoperative nausea and vomiting (PONV) is similar in patients receiving prophylactic midazolam or ondansetron when undergoing sevoflurane induction ................................................................................................................................................................................................................... …”