Preoxygenation with 20° head-up tilt provides longer duration of non-hypoxic apnea than conventional preoxygenation in non-obese healthy adults

Purpose Failed airway is the anesthesiologist's nightmare. Although conventional preoxygenation can provide time, atelectasis occurs in the dependent areas of the lungs immediately after anesthetic induction. Therefore, alternatives uch as positive end-expiratory pressure (PEEP) and head-up tilt during preoxygenation have been explored. We compared the conventional preoxygenation technique (group C) with 20°-up tilt (group H) and 5 cmH ₂O PEEP (group P) in non-obese individuals for non-hypoxic apnea duration. Methods A total of 45 patients were enrolled (15 in each group). After 5 min of preoxygenation, intubation was performed after induction of anesthesia with thiopentone and succinylcholine. After confirming the tracheal intubation by esophageal detector device and capnogram, all patients were administered vecuronium to maintain neuromuscular blockade and midazolam to prevent awareness. Post-induction, patients in all groups were left apneic in supine position with the tracheal tube exposed to atmosphere till the SpO₂ dropped to 93% or 10 min of safe apnea was achieved. Results The demographic data were comparable. Non-hypoxic apnea duration was higher with group H (452 ± 71 s) compared to group C (364 ± 83 s, P = 0.030).Group P did not show significant increase in the duration of non-hypoxic apnea (413 ± 86 s). There were no adverse outcomes or events. Conclusions Preoxygenation is clinically and statistically more efficacious and by inference more efficient in the 20° head-up position than with conventional technique in nonobese healthy adults. Although application of 5 cmH₂O PEEP provides longer duration of non-hypoxic apnea compared to conventional technique, it is not statistically significant.