Cardiodynamics in the rhesus macaque during dissociative anesthesia

Effects of dissociative anesthesia on cardiovascular dynamics and respiration were investigated in rhesus macaques to determine its use in nonhuman primates for restraint and minor surgical procedures. Respiration was spontaneous, and premedicants or anesthetic adjuvants were not used. Two doses of the anesthetic were administered (IM): 1.5 and 3.0 mg/kg. Depressant effects were observed in all variables initially; some cardiovascular variables eventually exceeded preinjection values after the higher (3.0 mg/kg) dose level. At a dose of 1.5 mg/kg, significant depression in myocardial contractility persisted for 20 minutes, and at 3.0 mg/kg for 50 minutes. Stroke volume was minimally affected initially, although significant increases occurred at 40 and 50 minutes after the 3.0 mg/kg injections. Heart rate was depressed by 5% and 7% in the animals given the small and large doses. Values were within control levels by 90 minutes after the anesthetic was injected, except respiratory rate and body temperature. We conclude that the dissociative anesthetic used produces neither marked nor prolonged cardiovascular effects. Since cardiovascular effects are absent by 90 minutes after the anesthetic was injected, dissociative anesthesia is a desirable technique for minor surgical procedures and restraint, especially before physiologic studies.