ACID-BASE BALANCE AND VENTILATION DURING STERNAL AND LATERAL RECUMBENCY IN FIELD IMMOBILIZED BLACK RHINOCEROS (DICEROS BICORNIS) RECEIVING OXYGEN INSUFFLATION: A PRELIMINARY REPORT

Posture, ventilation, and acid-base balance using auricular venous blood values (pH, lactate, base excess [BE], HCO3−, PO2, SO2, and PCO2), oxygen saturation of hemoglobin (SpO2), and end-tidal carbon dioxide (PETCO2) were compared between sternal (STE) and lateral (LAT) recumbency in free-ranging black rhinoceros (Diceros bicornis bicornis) receiving oxygen insufflation. Data are reported as median, minimum, and maximum (median [minimum, maximum]). Thirty-six desert-adapted black rhinoceros (20 male, 16 female; age 8 [1.5, 33] yr) were immobilized in Namibia in March and April of 2008, from a helicopter, by remote intramuscular injection with etorphine HCl, azaperone, and hyaluronidase. Time from darting to recumbency was 6.0 (3, 15.5) min. Data were organized into two sampling periods: sample period 1 (P1, collected within 0–20 min postdarting; 13 [6.5, 19] min) and sample period 2 (P2, collected between 20–40 min postdarting; 32 [22.3, 39] min). All animals were acidemic (pH 7.24 [7.07, 7.32]) and hypoxemic (PO2 51 [38, 95.2]; SO2 78 [64, 96] mmHg) after capture. Lactate at P1 was 7.2 (3.2, 16.8) mmol/l and decreased (P=0.01) to 4.6 (1.2, 10.9) mmol/l at P2. At P2, lactate was less (P=0.06) in LAT 3.5 (1.2, 8.6) mmol/l than in STE posture 7.4 (3.1, 10.9) mmol/l. In P2, PO2, SO2, and SpO2 were higher (P=0.02, 0.10, and 0.01, respectively) in STE than in LAT. End-tidal carbon dioxide in LAT was 38 (26, 47) mmHg and increased (P