Detrimental Effects of Removing End-expiratory Pressure Prior to Endotracheal Extubation

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Abstract
Patients recovering from acute respiratory insufficiency are usually not extubated until they can ventilate adequately while breathing spontaneously at ambient end-expiratory pressure (T tube). This period of T tube breathing might be detrimental to gas exchange since the endotracheal tube abolishes the expiratory retard produced by the glottis and thereby inhibits the patient''s ability to maintain adequate functional residual capacity (FRC). To test this hypothesis, pulmonary function of 17 patients was compared during T tube breathing and continuous positive airway pressure (CPAP) and after extubation. Intrapulmonary shunt was higher (P < 0.05) and PO2 [arterial O2 partial pressure] and FRC were lower (P < 0.05) during T tube breathing than during CPAP or after extubation. Shunt, PaO2 and FRC were similar during CPAP and after extubation. After extubation, there was an increase (P < 0.05) in mean expiratory airway pressure compared to T tube breathing. A comparison of patients extubated from T tube with patients extubated from CPAP showed no difference in postextubation shunt, PaO2 or FRC. Apparently, endotracheal intubation should be accompanied by low levels of CPAP and patients should be extubated directly from CPAP. The practice of placing patients in T tube prior to extubation should be abandoned as unnecessary and potentially harmful.