Effects of Preoxygenation with Tidal Volume Breathing Followed by Apneic Oxygenation with and without Continuous Positive Airway Pressure on Duration of Safe Apnea Time and Arterial Blood Gases

BACKGROUND: Application of continuous positive airway pressure (CPAP) helps to recruit collapsed areas of the lung, which improves the oxygen reserve. AIM OF THE STUDY: To compare the time to desaturate to 90% during apnea following preoxygenation and apneic ventilation with tidal volume breathing for 3 min with and without the application of CPAP. SETTINGS AND DESIGN: This prospective randomized study was conducted in a tertiary care institution. SUBJECTS AND METHODS: Twenty adult surgical patients were allocated into two groups. Group C patients were preoxygenated with 100% oxygen with CPAP of 20 cm H(2)O for 3 min. Group P patients were preoxygenated for 3 min without CPAP. In Group C, apneic oxygenation was initiated following induction and neuromuscular blockade with CPAP of 20 cm H(2)O. In Group P, no CPAP was applied. The study was terminated when the patient desaturated to 90%. STATISTICAL ANALYSIS USED: Chi-square test and Mann–Whitney test. RESULTS: Group C had a significantly longer apnea time as compared to Group P (816.00 ± 30.98 vs. 348.00 ± 122.64 s). Three patients in Group P desaturated to <90% by 3 min and the remaining soon after 6 min. No patient in Group C desaturated till 12 min of apnea. PaO(2) was significantly higher in Group C at 3 and 6 min of apnea. At 3 and 6 min, Group P had significantly lower saturation as compared to Group C. CONCLUSION: Preoxygenation with CPAP significantly delayed desaturation during apnea with significantly higher arterial partial pressure of oxygen as compared to preoxygenation without CPAP.