Some observations on nitrous oxide cylinders during emptying.

In an effort to correct misunderstandings and to establish the value of nitrous oxide pressure monitors on anaesthetic machines, the decrease of pressure within the nitrous oxide cylinders has been studied under a variety of clinical conditions. Although the matter had been clarified by 1946, the teaching of several current anaesthetic textbooks is still fallacious since an almost linear fall in cylinder pressure under constant flow conditions has been demonstrated. In addition, premature failure of nitrous oxide cylinder pressure due to cooling of the liquid contents has been noted. The value of cylinder pressure monitors is discussed in the light of these findings.