To the Editor

In order to decrease the frequency of breathing circuit disconnections or leaks, a type of mechanism (which is already used on some central venous catheter systems) involving a pin on the male end that is twisted with a half-turn into a groove on the female end could also be used on breathing circuits. This mechanism could be used at the attachment of the breathing circuit both to the machine and to the mask or endotracheal tube. This mechanism has the advantage of allowing the individual practitioner to choose whether to simply attach the circuit as we do now, or to twist the circuit to lock the attachment. One might choose not to lock the breathing circuit to the endotracheal tube, so that accidental stretch on the circuit might disconnect the circuit but not pull out the endotracheal tube; indeed, it might be preferable to have this mechanism only on the proximal end of the breathing circuit.

Another useful modification of breathing circuits would be to have the adapter site for the airway temperature probe closed with a luer-lock device rather than with a simple pop-off cap, to decrease the chances of accidental dislodgment of the cap. I once pressure-tested my circuit, preoxygenated the patient, induced anesthesia, then found that I had accidentally and unknowingly dislodged that cap while moving the circuit to preoxygenate the patient, resulting in a huge air leak and an inability to ventilate the patient until I found the source of the leak. This took longer than I would have liked, as I had not used that type of breathing circuit before, and as the open site was pointed down. I discovered the leak just as the patient began breathing spontaneously again as the pentothal was wearing off, fortunately I had not given muscle relaxants as I was planning to do this brief case by mask with assisted ventilation, so the patient did not develop hypoxemia or suffer any injury.

I would appreciate any assistance in communicating these suggestions to the appropriate ASA and manufacturer’s safety and standards committees.

David Blatt, M.D. Covina, CA