Clinical and Doppler echocardiographic evaluation of rabbits sedated with dexmedetomidine in combination with midazolam and morphine

Abstract

ABSTRACT: The objective of the present study was to evaluate clinical, cardiorespiratory, and Doppler echocardiographic changes in rabbits sedated with midazolam and morphine combined with or without dexmedetomidine. This study was a blinded, randomized, controlled experiment that included 16 adult male New Zealand rabbits weighing 3.1 ± 0.3 kg. The animals were sedated using one of the following protocols: 1 mg/kg midazolam and 2 mg/kg morphine (MIDA, n = 8), or 25 mg/kg dexmedetomidine, 2 mg/kg morphine and 1 mg/kg midazolam (DEX, n = 8). Sedation latency, duration of the sedation and recovery period, sedation scores, heart rate (HR), respiratory rate (f), peripheral oxygen saturation (SpO2), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), and recta temperature were recorded, and Doppler echocardiography was performed. Latency periods were 7.3±1.6 min in the DEX group and 10.9 ± 5.0 min in the MIDA group (P = 0.112). Sedation duration was 122.4±14 min in the DEX group and 71.2 ± 32 min in the MIDA group (P = 0.005), whereas recovery time was 35.7±17.7 min in the DEX group and 32.5 ± 25.3 min in the MIDA group (P = 0.743). The sedation scores for the DEX group were significantly higher than those for the MIDA group throughout the monitoring period. Reductions in HR, SAP, MAP, and DAP values were observed in both groups relative to baseline values, and were significantly lower in the DEX group compared to the MIDA group. Minimal Doppler echocardiographic changes were observed. Dexmedetomidine used in combination with midazolam and morphine incremented the quality and duration of sedation in rabbits. Both protocols elicited cardiorespiratory changes that were well-tolerated, with minimal changes in myocardial function.