Hypoxaemia after Surgery and Anaesthesia

THE significance of even transien't anoxia during anaesthesia has been w'idely recognised for many years but until recently the frequent occurrence and potendtiaJ danger of minor degrees of prolonged oxygen desaturation during the immediate post-operatlive period had not been appreciated. In 1962 however Nunn and Payne making use of the newer techniques of blood gas analysis demonstralted that some degree of arterial desaturation comimonly occurred after even 'the most trivial surgical procedures under general anaesthesia. S'ince then post-operative hypoxaemia has been intensively investigated and though the problem is not solved some of the relevant factors have been more clearly iden«tified. I't has of course been widely known since the work of Maier and Cournand in 1943 that lung surgery is associated with a substanytial reduction in arterial saturation which persists for severall dlays and even weeks after surgery, an observation later confirmed by Bjork and Hilty (1954) who drew attention to the significance of post-operative hypoxaemia in relation to the management of patients after open-chest surgery. Three years earl'ier Troell (195 1) had observed that 'major abdominal surgery was often followed by arterial desaturation both in patients who had breatlhed spontaneously and in those who had been artificially ventilated. In 1958 Gordh, Linderholm and Norlander who were the first workers in this field to use an oxygen electrode to determine oxygen tensions in blood obtained a mean fall in arterill oxygen tension of albout 16 mm.Hg. after major non-thoracic surgery in patients free from card'iovascular and respiratory disease.