AIRWAY PRESSURE CHANGES DURING ONE-LUNG VENTILATION

This investigation analyzed the changes in inspiratory airway pressure s during transition from two-lung to one-lung ventilation in patients tracheally intubated with a double-lumen endotracheal tube (DLT) using a classical method of intubation without fiberoptic bronchoscopy. All patients were anesthetized in a standardized fashion. Ventilation was accomplished with the Siemens 900 constant-flow mechanical ventilator (Solna, Sweden). Peak (Ppeak) and plateau (Pplateau) inspiratory airw ay pressures were recorded with an on-line respiratory monitor before and after clamping the tracheal limb of the DLT. The position of the D LTs was evaluated by fiberoptic bronchoscopy with the patient in supin e position. Of the 51 intubations, the DLT was malpositioned in 15 cas es (29.5%). Ppeak and Pplateau increased significantly when switched f rom two-lung ventilation to one-lung ventilation in both correctly and incorrectly positioned DLTs. When the DLT was in a correct position, Ppeak increased by a mean of 55.1% and Pplateau increased by a mean of 41.9%. When the DLT was malpositioned, this increase was significantl y larger (74.9% and 68.8%, respectively). Three tests commonly used as markers of malpositioned DLTs were evaluated based on the data of thi s study, and it was established that, although the pressure difference s related to position are statistically significant, as a single value , they cannot be used for clinical decision making.