Oxygen supplemented via face mask counteracts hypoxemia in capuchin monkeys (Sapajus spp.) under butorphanol-ketamine-midazolam restraint (2026)

Ferreira, M. E., Justo, A. A., Lima, A. F. K. T. et al.

Abstract

This prospective, randomized, complete crossover study evaluated the effects of supplemental oxygen on arterial oxygenation and recovery quality in adult capuchin monkeys (Sapajus spp.; n = 8; 6 males and 2 females) chemically restrained with intramuscular butorphanol (0.5 mg/kg), ketamine (15 mg/kg), and midazolam (1 mg/kg). Each monkey underwent 2 anesthetic events, separated by a 2-week interval: one breathing room air (G AIR) and one receiving oxygen via face mask at 3 L/min (GOXY), both conducted during dorsal recumbency. Heart rate (HR), respiratory rate (RR), peripheral oxygen saturation (SpO2), and rectal temperature were registered every 10 minutes for 45 minutes. Arterial blood gases were analyzed at 10 and 30 minutes postrestraint, with oxygen supplementation in G OXY initiated after the 10-minute time point and maintained for 35 minutes. Recovery was continuously video-recorded for later assessment of time to standing and recovery quality by one blinded and one nonblinded observer. At 10 minutes, 14 of 16 monkeys exhibited hypoxemia (partial pressure of arterial oxygen [PaO2] range: 48-81 mm Hg). By 30 minutes, PaO2 and arterial oxygen saturation (SaO2) increased significantly in GOXY, reaching 298-458 mm Hg and 100%, respectively, whereas GAIR animals remained hypoxemic (47-70 mm Hg and ≤92%, respectively). Pulse oximetry-derived SpO2 consistently overestimated saturation at low SaO2 values. The partial pressure of carbon dioxide (PaCO2) rose significantly in GOXY, with hypercapnia (PaCO2 range: 33-57 mm Hg) documented in 6/8 individuals at 30 minutes. In contrast, no cases of hypercapnia were observed in GAIR (PaCO2 range: 22-45 mm Hg) at the same time point. No significant between-group differences were detected in SpO2, HR, RR, or temperature over time. Time to standing and recovery quality were similar between groups. Supplemental oxygen via face mask effectively corrected hypoxemia in Sapajus spp. chemically restrained with butorphanol, ketamine, and midazolam.