Total Intravenous Anesthesia with Propofol Effectively Provides a Light Anesthesia Plane in Cynomolgus Male Monkeys (Macaca fascicularis) Undergoing Nociceptive Heat Stimulation.

Limited information exists regarding propofol's use as a total intravenous anesthesia in cynomolgus monkeys. This study investigated the continuous rate infusion (CRI) of propofol to provide light anesthesia during nociceptive testing. We hypothesized that a CRI of propofol would effectively induce light anesthesia in cynomolgus macaques during repeated weeks of C-fiber nociceptive (heat) stimulation. Four male cynomolgus monkeys were anesthetized with ketamine/dexmedetomidine (4 and 0.02 mg/kg, respectively, IM). Following intravenous catheter placement, atipamezole (0.5 mg/kg SC) was administered to reverse the effect of dexmedetomidine, and a propofol CRI (8-16 mg/kg/h) was initiated. Physiologic parameters, including systolic, diastolic, and mean arterial pressure, heart rate, respiratory rate, peripheral oxygen saturation, and body temperature, were recorded continuously. Animals were maintained with 100% oxygen via a mask and an intravenous electrolyte (Normosol-R; 5-10 mL/kg/h) infusion. Two hours after ketamine/dexmedetomidine administration, propofol doses were incrementally adjusted to elicit withdrawal reflexes using argon laser nociceptive (heat) stimulation (on digital pads of the forearms) with 5- to 15-minute intervals between stimulations. Propofol doses and physiologic parameters were recorded every 15 minutes. Following the baseline testing, the animals underwent a surgical procedure between sessions 1 and 2. Anesthesia and nociceptive stimulation were conducted over 6 nonconsecutive weeks. Test results showed that over the 6-week period the propofol doses remained unchanged, with variations not reaching statistical significance, and the physiologic parameters did not exhibit significant differences. These findings suggest that a propofol CRI of 8 to 16 mg/kg/h effectively provides light anesthesia in cynomolgus macaques during repeated nociceptive (heat) stimulation.