Effect of different volumes of BAL fluid on arterial oxygen saturation.

We monitored arterial oxygen saturation (StcO2) continuously using the OHMEDA Biox 3700 oximeter. We studied seven patients undergoing a 100 ml bronchoalveolar lavage (BAL-100), seven patients undergoing a 200 ml bronchoalveolar lavage (BAL-200), and seven patients during diagnostic fibreoptic bronchoscopy alone. Immediately following insertion of the bronchoscope a brief increase in StcO2 level (0.3-0.5%) was seen, followed by a gradual decline, never exceeding 2-5% during the diagnostic bronchoscopy. Introduction of lavage fluid into a segmental bronchus always produced a further decline in StcO2. In the BAL-100 group the fall did not exceed 7%, whereas in the BAL-200 group a fall of up to 15% from the baseline level was observed. Return to initial values was seen in most of the patients within 10 min following completion of the procedure. Only in those patients with the most profound StcO2 fall was this period increased, up to 30 min.