The purpose of this study was to determine the frequency and severity of arterial oxygen desaturation during and after endotracheal suctioning in a group of ventilator-dependent patients with acute respiratory failure (the majority of whom had underlying obstructive lung disease) and to evaluate the efficacy of several maneuvers designed to minimize desaturation. The adaptor method presented obviates both removal from and reconnection to the ventilator during suctioning, as well as the need to alter ventilator settings. It is concluded that on-ventilator adaptor suctioning is a simple and effective measure for minimizing suctioning-related arterial oxygen desaturation.