Cardiopulmonary effects of anaesthesia maintained by propofol infusion versus isoflurane inhalation in cheetahs (Acinonyx jubatus).

OBJECTIVE

To compare the cardiopulmonary effects of propofol total intravenous anaesthesia (TIVA) with isoflurane in cheetahs (Acinonyx jubatus) to evaluate feasibility for field use.

STUDY

DESIGN

Prospective clinical study.

ANIMALS: A group of 24 adult cheetahs, 12 per group.

METHODS

Cheetahs were immobilized with zolazepam/tiletamine (1.2 mg kg-1) and medetomidine [40 μg kg-1, both intramuscular (IM)] by darting. A maintenance protocol of propofol TIVA (group P) or isoflurane inhalation (group I) was assigned randomly to each cheetah. Anaesthesia was maintained for at least 60 minutes. Cheetahs breathed spontaneously throughout; oxygen was supplemented at 3 L minute-1. Cardiopulmonary parameters were recorded at 5 minute intervals and three arterial blood gas samples were analysed. Following maintenance, atipamezole was administered IM (200 μg kg-1) and recovery was observed. Data are reported as mean±standard deviation; variables over time were compared using a linear mixed model (fixed: time, treatment; random: cheetah).

RESULTS

Lack of response to manipulations was maintained in all cases (end-tidal isoflurane percentage 1.1±0.1%, propofol rate maintained at 0.1 mg kg-1 minute-1). The heart and respiratory rates were acceptable throughout maintenance. The end-tidal carbon dioxide tension increased slowly [44.0±5.0 mmHg (5.87±0.67 kPa)] with no differences between groups. All cheetahs were initially markedly hypertensive [mean arterial blood pressure (MAP): (163±17 mmHg)]. The MAP normalized for group I (125±30 mmHg) but remained high for group P (161±17 mmHg) (p < 0.001). Arterial carbon dioxide tension [48.9±14.6 mmHg (6.52±1.95 kPa)] never differed between groups. Initial arterial oxygen tension indicated borderline hypoxaemia, but improved with oxygen supplementation. Recovery time was 10.8±5.0 and 51.9±23.5 minutes for group I and group P, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: Both protocols provided acceptable cardiopulmonary values. Propofol may be an alternative to isoflurane for field use, but the prolonged recovery may make it less suitable for long-term anaesthesia.