The monkeys were sedated with ketamine hydrochloride (10 mg/kg intramuscularly [IM]) and placed in ventral recumbency on a special padded, heated examination table. An intravenous (IV) catheter was placed in the saphenous vein, and IV lactated Ringer’s solution administered (10 mL/kg per hour). Xylazine hydrochloride (0.35 mg/kg IV) was given to aid intubation. The animal was connected to a respirator and ventilated with 33% oxygen and 66% nitrous oxide (respiration volume 10–20 mL/kg, individually adjusted). The anesthesia was maintained with 1% isoflurane, and then the animal was paralyzed with pancuronium bromide (0.05 mg/kg IV) to prevent globe movement. The following parameters were closely monitored: body temperature, pulse rate, indirect mean arterial blood pressures (MAP; Dinamap Veterinary Blood Pressure Monitor 8300; Critikon, Inc., Tampa, FL), mucus membrane color, and end-expiratory CO2 partial pressures (Vet/Cap 7000 Capnometer; SDI Sensor Devices, Inc., Waukesha, WI). Systolic and diastolic blood pressures were maintained at levels of 70 to 100 and 38 to 55 mm Hg, respectively, with a mean blood pressure of 60 to 75 mm Hg. End-expiratory CO2 partial pressures were kept between 39 and 42 mm Hg by adjusting the respiration rate. The pancuronium bromide was administered (0.025 mg/kg IV) every 45 minutes until the end of the procedure.
At completion of the testing, the animals were recovered with neostigmine bromide (0.05 mg/kg intramuscularly [IM]) to reverse the neuromuscular blockage, and yohimbine hydrochloride (0.11 mg/kg IV) to reverse the remaining xylazine effects. As soon as spontaneous respiration resumed, each animal was extubated, placed back into its cage, and monitored until conscious.