Extubation from Ambient or Expiratory Positive Airway Pressure in Adults

Abstract

End-expiratory pressure is often used to improve arterial oxygenation and prevent atelectasis in intubated spontaneously breathing patients. To compare the effect of extubation from low levels of expiratory positive airway pressure (EPAP) to extubation from ambient airway pressure, functional residual capacity (FRC) and arterial blood O2 tension (PaO2) were measured in 12 spontaneously breathing patients during the following 3 conditions in the peri-extubation period: intubated at 5 cm H2O EPAP (EPAP 5), intubated at ambient airway pressure (EPAP 0), within 1 h after extubation. During EPAP 5, mean .+-. SE values for FRC (1864 .+-. 230 ml) and PaO2 (114 .+-. 8 torr) were the same as those obtained after extubation (FRC = 1794 .+-. 159 ml, PaO2 = 117 .+-. 5 torr). FRC (1600 .+-. 186 ml) and PaO2 (106 .+-. 8 torr) were lower during EPAP 0 than after extubation or EPAP 5 (P < 0.01-0.05). The magnitude of increase in FRC and PaO2 on extubation from EPAP 0 varied inversely with the patient''s lung-thorax compliance (r = -0.84, P < 0.005). A period of EPAP 0 is not necessary in the weaning period; it may be deleterious in patients with compromised lung-thorax mechanics.