SummaryA definite relationship between the use of contaminated anaesthetic equipment and subsequent pulmonary infection remains to be established. There is however indirect and circumstantial evidence suggesting that cross-infection may occur, and further an increased susceptibility of surgical patients to pulmonary infections has been demonstrated. Decontamination should be recommended bejore the equipment is re-used. Pasteurisation may protie sufficient and this can be obtained employing a specially designed dish-washing machine.

No abstract

Xanthines and barbiturates have opposing effects on cerebral function and metabolism. Since the xanthine theophylline is known to inhibit the enzyme 5'-nucleotidase, and thus endogenic adenosine release, an in vitro experiment was conducted on the assumption that theophylline and phenobarbital may have an opposing effect on 5'-nucleotidase activity. This assumption was confirmed. The hypothesis that barbiturates in general cause an increase in endogenic adenosine release seems compatible with the known functional and metabolic effects of barbiturates. Furthermore, accepting the hypothesis that cellular hypoxic-anoxic survival may ultimately depend on salvage of adenine nucleotides, this may even explain the dichotomy in the effect of barbiturates when used for protection of a hypoxic-anoxic insult.

The efficiency of two patient-dependent, variable performance techniques of oxygen therapy in relieving hypoxaemia after upper abdominal surgery was compared. A high-flow system delivered a humidified mixture of oxygen 2 litre min-1 and air 13 litre min-1 through a cannula inserted into the anterior nares. The low-flow system delivered 2 litre min-1 of dry oxygen into the nasopharynx through a catheter. Thirteen otherwise healthy patients received either high-flow oxygen therapy for 30 min followed by low-flow oxygen therapy for a further 30 min after operation or the same therapy in reverse order. With the patients breathing room air, arterial hypoxaemia could be demonstrated with Pao2 inversely related to age. The increase of Pao2 during either oxygen treatment was significantly greater with the low flow system.

LETTERS TO THE EDITOR SIR:The reports on thermal injuries due to warming blankets t-4 stress the importance of ensuring safe operation of these. The work of Craig and Pask 5 thus meets an evident need. We have but one objection to the construction presented, and that is the use of mercury in glass thermostats. In the six cases of burns caused by heating mattresses which we have experienced in our clinic, 4 two could with certainty be attributed to defects in operation of the mercury in glass thermostats. On both occasions the malfunction was caused by the presence of air bubbles in the mercury column. As a consequence the department has participated in the construction of a safety device without incorporation of mercury in glass thermostats 6.