Endotracheal suctioning (ETS) through a closed-airway-system adapter during mechanical ventilation has been recommended as a simple technique to minimize suction-related arterial oxygen desaturation and eliminate the need for preoxygenation or removal of the patient from the ventilator. Because ETS in a closed system could reduce lung volume and thereby lead to desaturation, we studied the effects of closed-system ETS on arterial oxygen saturation (SaO2), with and without preoxygenation, in 17 adult patients with acute respiratory failure, 10 on assisted mechanical ventilation (AMV) and 7 on intermittent mandatory ventilation (IMV). Each patient was suc-tioned (15 s, 25 L/min, 14 Fr) with and without 3-minute preoxygenation (FIO₂ = 1.0, same tidal volume) while SaO2 was being measured with an ear oximeter. Two suction periods, 1 minute apart, were followed by a 30-minute rest period, and the procedure was repeated, with the order of preoxygenation and no preoxygenation randomized. After preoxygenation, SaO2 fell from 99.8 ± 0.3% (mean ± SD) to 99.3 ± 0.7%; in individual patients SaO2 fell a maximum of 2%. Without preoxygenation, values were significantly lower: 97.7 ± 1.6 and 94.4 ± 5.6%, respectively (P < 0.05), with a maximum individual fall of 22%. Without preoxygenation, SaO2 during ETS was lower in AMV patients than in IMV patients (P < 0.05). We conclude that the significant desaturation that can occur in AMV patients during and after closed-airway-system ETS without preoxygenation is likely due to flow deficit in the closed-airway system.
CRAIG et al. (Mon,) studied this question.