Pre-oxygenation: A comparison of three techniques

Background: Pre-oxygenation is a time honoured ritual carried out in a variety of circumstances. Various methods of pre-oxygenation have been proposed and followed world wide with vaviable success. The purpose of this study was to evaluate the need for pre-oxygenation prior to the induction of general anaesthesia and also compare the effects of three techniques of pre-oxygenation, on peripheral oxygen saturation and vital parameters. Patients and Methods: Hundred ASA grade I and II patients in the age group of 20-40 years were studied under four equal groups. Group I did not receive any pre-oxygenation, group II received pre-oxygenation in the form of four vital capacity breaths, group III and group. IV received pre-oxygenation for 3 and 5 minutes respectively. Results: It was observed that after one minute of post induction, apnea, patients in group I had a reduction in oxygen saturation to a mean of 79.92 ± 3.328%, in comparison to 87.24 ± 2.368% in group II, 96.84 ± 1.972% in group III and 99.28 ± 0.737% in group IV . It was also observed that vital parameters at the end of 1 min of apnea were close to baseline values in group III and group IV. The results were analysed using the "Analysis of Variance" (ANOVA) method. Conclusion: Pre-oxygenation for 5 minutes prior to induction of general anaesthesia is the best technique among the three, as it provides maximum safe period before the hypoxia sets in after induction of general anaesthesia and also the vital parameters remain closer to baseline.