Isoflurane sparing and the influence on cardiovascular and pulmonary parameters through a continuous romifidine hydrochloride infusion during general anaesthesia in horses - a clinical study

Abstract

In a double-blinded study of 20 horses (Group I: body mass Ø 488 ± 90 kg, age 5 ± 4 years; Group II: body mass Ø 545 ± 160 kg, age 5.5 ± 5 years) the synergistic effect of romifidine hydrochloride (Sedivet®, Boehringer Ingelheim) on the inhalation anaesthesia with isoflurane was examined. The objective of the investigation was to measure the effect of a continuous administration of romifidine (0,3 μg kg-1 min) on the isoflurane amount consumed during general anaesthesia in elective surgery cases. Furthermore, the influence of the additional sedative on relevant cardiovascular and pulmonary parameters was examined. Exhaled isoflurane concentration, medium arterial blood pressure (maBP), heart rate (HR), breath per minute volume (BPM), tidal volume (TV) and the end-expiratory carbon dioxide content (Et CO2) were noted continuously and evaluated statistically. Every 15 minutes the arterial carbon dioxide partial pressure (PaCO2), as well as, the arterial oxygen partial pressure (PaO2) and blood pH was measured. The BPM, TV, P aCO2 and blood pH parameters did not show significant differences between the two groups. The horses which received the continuous infusion of romifidine showed a significant reduction in the inhaled isoflurane concentration compared to the control group (p ≤ 0.05). Additionally, the romifidine group clearly exhibited a less negative effect on maBP (p ≤ 0.05). This effect was further exhibited by the fact that the horses in the control group needed dobutamine more frequently to support cardiovascular function (p ≤ 0.05). The continuous administration of romifidine led to a beneficial effect on the cardiovascular and pulmonary parameters during isoflurane general anaesthesia. Isoflurane consumption was reduced significantly by the romifidine infusion.