comparison of pre-oxygenation with single vital capacity breath technique and tidal volume breathing technique for adult patients undergoing general anaesthesia

Background: pre-oxygenation before induction of general anaesthesia is widely used for enhancing oxygen reserves and preventing hypoxia. several techniques for pre-oxygenation have been described. this study was designed to compare the pao2   and eto2 with single vital capacity breath technique (svcb) and tidal volume breathing technique (tvb) for adult patients undergoing general anaesthesia.methods: fifty patients were pre-oxygenated with both techniques - first svcb then tvb separated by five minutes of breathing room air or till eto2 & pao2 values reached baseline values (whichever was later). abg samples & eto2 readings were taken before pre-oxygenation & every thirty seconds for three minutes in both techniques.results: pre-test, mean pao2 and eto2 values of both techniques (svcb and tvb) were similar. in svcb technique, the mean pao2 (mmhg) and eto2 (%) significantly increased at 30 seconds (p ≤ 0.001) from 95.26 and 17.14 (pre-test time) to 304.34 and 92.48 respectively. in tvb technique, an exponential increase was noted. the mean pao2 (mmhg) and eto2(%) significantly increased at 180 seconds (p ≤ 0.001) from 96.26 and 16.26 (pre-test time) to 305.64 and 93.08 respectively. peak values of oxygenation in both groups were similar but achieved at different time points.conclusion: svcb technique achieves high oxygenation rapidly but is not sustained thus can be used for rapid sequence induction though not recommended for difficult airway scenarios. tvb technique also achieves high oxygenation but steadily. tvb may be used for induction, including, rapid sequence induction but after 3-5 minutes of pre-oxygenation.