EFFECTS OF A CARFENTANIL-XYLAZINE COMBINATION ON CARDIOPULMONARY FUNCTION AND PLASMA-CATECHOLAMINE CONCENTRATIONS IN FEMALE BONGO ANTELOPES

Objective-To determine the effects of an IM administered carfentanil-x ylazine combination on cardiopulmonary variables and plasma catecholam ine concentrations and to validate use of pulse oximetry in bongo ante lopes. Animals-8 healthy adult females. Procedure-Antelopes were immob ilized with carfentanil citrate (8.3 mu g/kg of body weight, IM) and x ylazine hydrochloride (0.79 mg/kg, IM). Hematologic values and plasma biochemical and catecholamine concentrations were determined at the be ginning and end of immobilization. immediately after induction of immo bilization and every 15 minutes thereafter, cardiopulmonary variables were determined. Results-Induction time after carfentanil-xylazine adm inistration was 6 +/- 2 minutes. At 15 and 45 minutes after immobiliza tion and thereafter, significant decrease in heart and respiratory rat es, respectively, were observed. After 15 minutes of immobilization, a ll antelopes had developed mild hypoxemia, which resolved after nasal insufflation with 100% oxygen. Pulse oximetry readings underestimated arterial blood gas values, but reliably indicated trends in arterial o xygen desaturation. Antelopes developed hypoxemia after oxygen adminis tration was terminated al the end of the procedure, prior to reversal of immobilization. Norepinephrine concentrations increased significant ly (P < 0.05), and 3,4-dihydroxyphenylacetic acid concentrations decre ased significantly at the end of the anesthetic event. Immobilization of all antelopes was reversed, using antagonists naltrexone and yohimb ine hydrochloride. Time to standing was 3 +/- 1 minutes, and renarcoti zation was not observed. Conclusions and Clinical Relevance-The carfen tanil-xylazine combination al the dosage used induced hypoxemia, prono unced arterial hypertension, and significant increase in plasma norepi nephrine and decrease in plasma 3,4-dihydroxyphenylacetic acid concent rations in bongo antelopes. Supplemental administration of oxygen is r ecommended. Pulse oximetry is a useful tool to monitor trends in arter ial oxygen desaturation, but does not substitute for arterial blood ga s analysis.