The effects of endotracheal suctioning were studied in 38 patients. A significant decline in arterial oxygen tension and saturation was noted in all patients. A new double lumen suction catheter that simultaneously insufflates oxygen while suctioning was tested in these same patients and was found to prevent hypoxemia in all patients. We recommend that the insufflation catheter be added to the protocol of hyperventilation with 100% oxygen to help prevent suction-induced hypoxemia.