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

Background. Evidence suggests that respiratory function is impaired poststr oke. Body position is known to influence respiratory function in normal sub jects and those with respiratory pathologies. Its effect on respiratory fun ction after stroke has received little attention. However, one study; sugge sts that some positions used in clinical practice may adversely influence r espiratory function. This study therefore aimed to identify resting positio ns that maintain arterial oxygen saturation (SaO(2)) at optimal levels, cha nges in SaO(2) during time spent in the test position, and differences in S aO2 among the positions investigated. Method. A within-subject, two-center clinical study was made. Patients in t he first 72 hours following mild to moderately severe stroke were allocated a randomized sequence of four positions. One hour was spent in each positi on. SaO(2) was recorded each minute by pulse oximetry with a finger probe. Mean values for the hour were calculated. Results. Mean arterial oxygen saturation values for all patients were >90% for the hour spent in each Lest position for all patients. There were no ch anges in arterial oxygen saturation across the hour spent in the test posit ions (repeated-measures analysis of variance). No differences in arterial o xygen saturation were identified among positions (analysis of covariance). Discussion. The saturation levels recorded corresponded to those observed i n studies of normal elderly persons. The positions tested may be recommende d for use in clinical practice to maintain arterial oxygen saturation in pa tients in the first 72 hours following mild to moderately severe stroke.