We studied four methods of endotracheal suctioning in 6 adult hypoxemic patients who required positive end-expiratory pressure (PEEP). Method I provided pre- and postsuctioning hyperoxygenation via a ventilator, with the suction catheter being inserted through an uncapped swivel adapter. Method II was like Method I except that hyperinflation via the ventilator was added. Method III employed a bag resuscitator instead of using a ventilator for hyperoxygenation and hyperinflation, with the suction catheter inserted through a swivel adapter. Method IV employed a resuscitator bag for hyperoxygenation and hyperinflation, like Method III, but in Method IV the resuscitator was removed from the endotracheal tube for suctioning and the catheter was inserted directly into the artificial airway. Suctioning lasted 15 seconds in each method. A control procedure was carried out to determine the effect on PaO2, FiO2, and tidal volume of removing the swivel adapter cap for 15 seconds but not suctioning the airway. We found that (1) the ventilator methods (I & II) were more effective than the bag techniques (III & IV) in terms of PaO2 levels before, during, and after suctioning (P < 0.05); (2) the ventilator techniques were more effective than the bag methods in delivering increased tidal volumes (P < 0.02); and (3) patients with low intermittent mandatory volume rates had a greater drop in PaO2 than other patients when the resuscitator was removed for suctioning (Method IV). (Baker PO, Baker JP, Koen PA. Endotracheal Suctioning Techniques in Hypoxemic Patients. Respir Care 1983;28:1563-1568.