British Journal of Anaesthesia 1991; 67: 464-^166 EFFECTIVENESS OF PREOXYGENATION IN MORBIDLY OBESE PATIENTS

The time taken for the oxygen saturation (Sp0J to decrease to 90 % after preoxygenation was studied in six morbidly obese patients and six matched controls of normal weight. During apnoea the obese patients maintained Sp02> 90 % for 196 (SD 80) s(range55-208 s), com-pared with 595 (so 142)s (range 430-825 s) in the control group (? < 0.001). One patient in the obese group had desaturation before the onset of complete relaxation and trachea / in-tubation, without complications. Bedside lung function tests were not significantly different between groups and cannot be used as a predictor of the effectiveness of preoxygenation