BLOOD GASES IN ROUTINE ANAESTHESIA

This study shows a very wide range of preoperative arterial oxygen tensions in all age groups so that it is impossible to predict clinically the oxygen status without blood gas analysis. Without a preoperative baseline, any random sample will be difficult to interpret. Thoracotomies are interesting in that there are marked decreases in arterial oxygen tension when the lung is collapsed during endobronchial anaesthesia. Even 100 per cent oxygen in the inspired mixture will not insure an arterial tension of 100 mm Hg. Oxygen tension in the patient with an intact thorax is directly related to the oxygen concentration in the inspired gases. This study indicates that the use of accepted routine anaesthetic techniques and agents in routine surgical cases does not necessarily guarantee that a satisfactory physiological blood gas status will be achieved. © 1969 Canadian Anesthesiologists.