Constant-Rate Infusion of Dexmedetomidine to Manage Thiopental Anesthesia during Intracranial Surgery in Cynomolgus Macaques (Macaca fascicularis).

Macaques (Macaca spp.) are often used as animal models in biomedical research involving a neurosurgical approach. The development of new anesthetic techniques is pivotal for these studies. Studies in human anesthesia for intracranial surgery have shown that dexmedetomidine infusion reduces the incidence of cardiocirculatory complications in the perioperative period, reduces the need for supplemental analgesia, and provides an analgesic effect analogous to that of remifentanil. Data regarding the anesthetic effects of dexmedetomidine infusion in NHP including Macaca spp. are currently unavailable. The study population comprised 5 healthy cynomolgus macaques (Macaca fascicularis) that underwent intracranial surgery. On the day of surgery, the subjects were sedated with intramuscular ketamine (8 mg/kg) and dexmedetomidine (0.02 mg/kg). Anesthesia was induced with thiopental (3 mg/kg IV) and maintained by using constant-rate infusion of thiopental (3 mg/ kg/h); analgesia was provided by constant-rate infusion of dexmedetomidine (0.012 mg/kg/h). Atipamezole (0.1 mg/kg IM) was administered at the end of the surgical procedure. The median heart rate increased after sedation, reaching its highest level at 60 min (91.0 6.9 bpm); the highest systolic blood pressure (119.6 10.5 mm Hg) occurred at 75 min. No animal experienced respiratory arrest, and all recovered within 6 min after atipamezole administration. In cynomolgus macaques, dexmedetomidine constant-rate infusion provided adequate analgesia and stable hemodynamic control. Using dexmedetomidine as an adjunct to thiopental-maintained anesthesia may be advantageous in healthy NHP undergoing intracranial surgery.