ObjectivePatients in the intensive care unit (ICU) undergo acute increases in metabolic and cardiopulmonary demands in response to routine care interventions, such as chest physical therapy. This study examined whether the short-acting drug, propofol, could blunt the responses to chest physical therapy.DesignProspective, randomized, crossover (placebo vs. drug) study.SettingUniversity hospital surgical ICU.PatientsPostoperative ICU patients being ventilated in the synchronized intermittent mandatory ventilation mode.InterventionsTwo groups of 16 patients were studied. Each patient received two successive sessions of chest physical therapy. In random fashion, one was preceded by the administration of placebo and the other by an intravenous bolus of propofol (0.75 mg/kg in one group and 0.35 mg/kg in the other group). Each session was preceded and followed by a period of rest.Measurements and Main ResultsThe increases in oxygen uptake, CO2elimination, oxygen delivery, heart rate, and systolic blood pressure associated with chest physical therapy were attenuated with the low dose and suppressed with the high dose of propofol. The PaCO2concentration was slightly increased during both placebo and drug administration.ConclusionsPropofol, in the doses administered in this study, significantly reduced the hemodynamic and metabolic stresses caused by chest physical therapy.(Crit Care Med 1996; 24:612-617)