Preliminary investigation into the ventilatory effects of midazolam in isoflurane-anaesthetised goats

Abstract

The ventilatory effects of intravenous midazolam (MDZ) were evaluated in isoflurane- anaesthetised goats. Eight female goats aged 2–3 years were fasted from food and water for 12 h. Anaesthesia was then induced using a face mask with isoflurane in oxygen, whilst the trachea was intubated with a cuffed tracheal tube and anaesthesia maintained with isoflurane at 1.5% end-tidal concentration. Ventilation was spontaneous. The goats were treated with either a saline placebo (PLC) or MDZ intravenously at 0.2 mg/kg. Analysis of variance for repeated measures was used for the analysis of data. Significance was taken at the 0.05 level. Differences between treatments were not statistically significant (p > 0.05) for tidal volume, ventilation rate, tidal volume/kg (V_T/kg) and end-tidal carbon dioxide partial pressure. Within treatments, V_T and V_T/kg differed 5 min after MDZ administration; this was statistically significant (p < 0.05). The occurrence of apnoea in the MDZ-treated goats was statistically significant (p = 0.04) compared with the PLC treated goats. Intravenous MDZ at 0.2 mg/kg administered to isoflurane-anaesthetised goats may result in transient apnoea and a mild decrease in V_T and V_T/kg.