Changes in pulmonary mechanics after fiberoptic bronchoalveolar lavage in mechanically ventilated patients

Objective: We prospectively assessed the impact of bronchoalveolar lavage (BAL) on respiratory mechanics in critically ill, mechanically ventilated patients. Study design: Mechanically ventilated patients underwent BAL of one lung segment using 5 x 20 ml of sterile, physiologic saline with a temperature of 25-28 degrees C. The fractional inspired oxygen was increased to 1.0, but ventilator settings were otherwise left unchanged. Static pulmonary compliance, pulmonary resistance, alveolar ventilation, and serial dead space were measured 60 min and 2 min before and 8, 60, and 180 min after BAL to assess the consequences of the procedure. In addition, blood gases [partial pressure of carbon dioxide in arterial blood (PaCO2) and arterial oxigen tension (PaO2)], hemodynamic variables (heart rate, systolic and diastolic blood pressure), and body temperature were recorded at the same time points. Setting: Intensive care unit of a university hospital. Patients: 18 consecutive critically ill, mechanically ventilated patients. Results: Pulmonary compliance decreased by 23% (p < 0.05) and pulmonary resistance increased by 22% (p < 0.05) shortly after BAL. The changes in pulmonary compliance and resistance were more than 30% in one third of the patient population. One hour after the procedure, PaO2 was significantly lower and PaCO2 significantly higher than before the procedure. Three hours after the procedure, pulmonary resistance returned to pre-BAL values but compliance remained 10 % below baseline values (p < 0.05). Conclusion: BAL in mechanically ventilated patients is associated with deterioration of pulmonary mechanics and function.