Abstract:
During apnoea following induction of anaesthesia, morbidly obese patients may suffer a rapid decrease in oxygen saturation. This study compares pre-oxygenation alone with pre-oxygenation followed by nasopharyngeal oxygen insufflation on the onset of desaturation occurring during the subsequent apnoea. A randomised controlled trial was performed in 34 morbidly obese patients undergoing gastric bypass or gastric band surgery. Seventeen patients received nasopharyngeal oxygen supplementation following pre-oxygenation (Study group, body mass index = 41.8 (6.9) kg.m-2), and the other 17 patients received pre-oxygenation alone (Control group, body mass index = 42.7 (5.4) kg.m-2). Time from the onset of apnoea until Sp o2 fell to 95percent was compared between the two groups with a cut-off of 4 min. In the control group, the Spo2 fell from 100percent to 95percent during the subsequent apnoea in 145 (27) s, with a significantly negative correlation (r2 = 0.66, p andlt; 0.05) between the time to desaturation to 95percent and the body mass index. In the study group, the Spo2 was maintained in 16 of 17 patients at 100percent for 4 min when apnoea was terminated. In conclusion, nasopharyngeal oxygen insufflation following pre-oxygenation in morbidly obese patients delays the onset of oxyhaemoglobin desaturation during the subsequent apnoea. © 2007 The Authors Journal compilation 2007 The Association of Anaesthetists of Great Britain and Ireland.