The management of acute hypoxia

Abstract

ACUTE HYPOXIA may develop in a large variety of medical and surgical conditions. It may range from relatively mild or short-lasting episodes to the ultimate in severity as exemplified' by ventricular fibrillation and cardiac standstill. The subject of acute hypoxia has been dealt with extensively in the literature, but the main emphasis usually has been laid on cardiac arrest. Yet, any condition or event, affecting either respiration or circulation or both, which hcutely leads to suboxygenation of tissues constitutes acute hypoxia.While it can be readily appreciated that t]he diverse causes of acute hypoxia and their combination are legion, it is equally clear that, either because of the mild degree or because of extremely short duration, obvious clin/ical signs and ,sequelae may be entirely absent or at least they cannot be detected with the diagnostic means at our disposal. "Hence, from a practical point of view, such hypoxic events are of little significance.On the other hand, cardiac arrest is by no means the only acute hypoxic episode in which sequ.elae of hypoxia are present and need vigorous treatment. All too often treatment for one of the less dramatic hypoxic events is not instituted and the fact is accepted that the patient will regain consciousness less promptly than might be expected otherwise, that he will be confused, nauseated, or restless. This applies equally to anaesthesia, diver,~e states of unconsciousness, and hypoxia not associated with coma. It behoves us then in all cases of acute hypoxia to weigh the severity and duration of the event and decide whether for a particular patient nnder the particular circumstances prevailing the hypoxia was severe enough in degree and duration to merit active treatment.An attempt will be made to describe the management of severe h'ypoxia.TREATMENT (a) It is a general principle that whenever an untoward reacti~m occurs from whatever cause, the first step must be to correct that cause if it is known. This same principle applies to the management of acute hypoxia. If at ~11 possible the aetiological factor responsible for the hypoxia must be identified[and corrected and a determined effort must be made to provide adequate tissue oxygenation.(b) Because of its great intolerance to deprivation of oxygen, the central nervous sytem, and in particular the brain, present the most formldable obstacle to satisfactory recovery from acute hypoxia. The crudeness of our tests prevents us from ascertaining minor degrees of cerebral imp~drment while in extreme cases