The effect of body position on arterial oxygen saturation in acute stroke

Evidence suggests that respiratory function is impaired poststroke. Body position is known to influence respiratory function in normal subjects and those with respiratory pathologies. Its effect on respiratory function after stroke has received little attention. However, one study suggests that some positions used in clinical practice may adversely influence respiratory function. This study therefore aimed to identify resting positions that maintain arterial oxygen saturation (SaO2) at optimal levels, changes in SaO2 during time spent in the test position, and differences in SaO2 among the positions investigated.

A within-subject, two-center clinical study was made. Patients in the first 72 hours following mild to moderately severe stroke were allocated a randomized sequence of four positions. One hour was spent in each position. SaO2 was recorded each minute by pulse oximetry with a finger probe. Mean values for the hour were calculated.

Mean arterial oxygen saturation values for all patients were >90% for the hour spent in each test position for all patients. There were no changes in arterial oxygen saturation across the hour spent in the test positions (repeated-measures analysis of variance). No differences in arterial oxygen saturation were identified among positions (analysis of covariance).

The saturation levels recorded corresponded to those observed in studies of normal elderly persons. The positions tested may be recommended for use in clinical practice to maintain arterial oxygen saturation in patients in the first 72 hours following mild to moderately severe stroke.