Arterial oxygen saturation and posture in acute stroke.

Patients with acute stroke are at risk of hypoxaemia and the degree of oxygen desaturation may depend on posture. Using a fingertip pulse oximeter, we studied the effects of different nursing positions on arterial oxygen saturation (SaO2) in ten elderly patients within 48 hours of a hemiplegic stroke and 10 age-matched controls admitted to hospital with other acute illnesses. Mean SaO2 was consistently higher in the controls than the stroke patients in all recumbent positions, but when patients were propped up the difference between the groups was statistically insignificant. The difference between semirecumbent and lying SaO2 values was then tested in a further nine stroke patients. Overall the mean SaO2 was significantly higher and, in at least four cases, the duration of episodes of desaturation (SaO2 < 90%) was substantially less when the patients were propped up. We suggest that, wherever possible, acute stroke patients should be nursed sitting up to minimize the risk of oxygen desaturation and possible aggravation of ischaemic brain damage.