Objective: To evaluate the time to hemoglobin oxygen desaturation in chickens (Gallus gallus domesticus) with and without preoxygenation before isoflurane induction of anesthesia and rocuronium-induced apnea.
Study design: Prospective, randomized crossover study.
Animals: A total of 10 healthy adult Lohmann Brown-Lite hens.
Methods: Hens were anesthetized with isoflurane for intravenous (IV) and intraarterial catheter placement and allowed to fully recover from anesthesia. Hens in the preoxygenation treatment were administered oxygen (2 L minute-1) via a facemask for 3 minutes prior to induction of anesthesia with 3% isoflurane in oxygen. In the alternative treatment, hens were not preoxygenated prior to induction of anesthesia with isoflurane in oxygen. Apnea was then induced with rocuronium bromide (1.0 mg kg-1) administered IV, and anesthesia was maintained with IV propofol infusion. A cloacal pulse oximeter measured hemoglobin oxygen saturation (SpO2). Time was recorded from the start of apnea until SpO2 was 90% (desaturation). The trachea was intubated, and anesthesia was maintained with isoflurane in oxygen with manual ventilation until spontaneous breathing returned and SpO2 ≥ 99%. PaO2 was measured before each treatment, after preoxygenation, postinduction and at desaturation. Data were analyzed between treatments using Wilcoxon matched-pairs signed rank tests with Holm-Šidák multiple comparison test, and within treatments using Friedman test with Dunn's multiple comparison test (p < 0.05). Data are reported as median (range).
Results: Time from start of apnea until hemoglobin desaturation was not significantly different between preoxygenated and nonpreoxygenated hens [26.5 (16-50) seconds and 24.0 (5-57) seconds, respectively; p = 0.25]. No differences in PaO2 between treatments were observed at any time point.
Conclusions and clinical relevance: Preoxygenation for 3 minutes before isoflurane mask induction of anesthesia and apnea does not significantly increase time until desaturation in hens.
Keywords: anesthesia; apnea; avian; desaturation; induction; preoxygenation.
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