Seated and semi-recumbent positioning of the ventilated intensive care patient – Effect on gas exchange, respiratory mechanics and hemodynamics

ObjectivesTo compare the effect of semi-recumbent and sitting positions on gas exchange, respiratory mechanics and hemodynamics in patients weaning from mechanical ventilation.BackgroundUpright positions are encouraged during rehabilitation of the critically ill but there effects have not been well described.MethodsA prospective, randomized, cross-over trial was conducted. Subjects were passively mobilized from supine into a seated position (out of bed) and from supine to a semi-recumbent position (>45° backrest elevation in bed). Arterial blood gas (PaO2/FiO2, PaO2, SaO2, PaCO2 and A–a gradient), respiratory mechanics (VE,VT, RR, Cdyn, RR/VT) and hemodynamic measurements (HR, MABP) were collected in supine and at 5 min and 30 min after re-positioning.ResultsThirty-four intubated and ventilated subjects were enrolled. The angle of backrest inclination in sitting (67 ± 5°) was greater than gained with semi-recumbent positioning (50 ± 5°, p < 0.001). There were no clinically important changes in arterial blood gas, respiratory mechanic or hemodynamic values due to either position.ConclusionsNeither position resulted in significant changes in respiratory and hemodynamic parameters. Both positions can be applied safely in patients being weaned from ventilation.