Does continuous positive airway pressure compensate for loss of glottic function during tracheal intubation?

Adult patients with acute lung injury (ALI) exhibit increased PaO2 when receiving continuous positive airway pressure (CPAP). Some have increased PaO2 after extubation. To determine the role a competent glottis played in improving gas exchange, we anesthetized seven rabbits and inserted central venous and carotid artery catheters. After recovery from anesthesia, ALI was induced with oleic acid (0.08 ml/kg). Twenty-four hours later, the animals were sedated and placed in a sling. The pHa and blood gas tensions were measured. The animals were placed supine and were given inhalation anesthesia to facilitate tracheal intubation. A polyethylene catheter was placed slightly distal to the tracheal tube outlet to measure tracheal pressure (PT). Intubated rabbits were repositioned in the sling and were given either zero end-expiratory pressure (ZEEP) or 5 cm H2O CPAP, alternately. After the animals had breathed room air for 60 min, pHa and blood gas tensions were again measured, and PT was recorded. Animals were extubated, but the PT catheter was left in place. Data were collected again 60 min later, the catheter was removed, and the animals were returned to their cages. Forty-eight hours after onset of ALI, the protocol was repeated.(ABSTRACT TRUNCATED AT 250 WORDS)