Influence of dexmedetomidine-propofol-isoflurane and medetomidine-propofol-isoflurane on intraocular pressure and pupil size in healthy dogs

Abstract

ABSTRACT:The present prospective, randomised, double-blinded clinical study was designed to investigate the commonly used anaesthetic combinations of dexmedetomidine-propofol-isoflurane and medetomidine-propofolisoflurane on intraocular pressure and pupil size in dogs. Forty client-owned healthy dogs with no ocular abnormalities, average body weight of 25.7 ± 13.1 kg (mean ± SD) and aged 3.7 ± 2.7 years, were enrolled. Twenty four males and 16 females were included. Dogs were allocated randomly to receive dexmedetomidine i.v. at 0.005 mg/ kg, dexmedetomidine at 0.01 mg/kg, medetomidine at 0.01 mg/kg or medetomidine at 0.02 mg/kg. Ten minutes later anaesthesia was induced in all dogs with propofol and maintained with isoflurane in oxygen-air. Intraocular pressure, pupil size, heart rate, respiratory frequency and arterial blood pressures (SAP, DAP) were measured prior to (baseline) and at 10 (before propofol), 20, 30, 40, 50 and 60 min after dexmedetomidine or medetomidine administration. Oxygen saturation of haemoglobin (SpO 2 ) and end-tidal CO 2 concentration (EtCO 2 ) was monitored following anaesthesia induction. Data were analysed using Anderson-Darling and Bartlett's tests for data distribution and homogeneity of variance confirmation and ANOVA followed by Dunnett's tests for multiple comparisons. Changes were considered significant when P < 0.05. Following drug administration, pupil size, heart rate and respiratory frequency decreased significantly within groups, but did not differ between groups. No significant changes in intraocular pressure, SAP and DAP within and between groups, and SpO 2 or EtCO 2 between groups, were observed. Comparable doses of dexmedetomidine or medetomidine combined with propofol and isoflurane induced reductions in pupil size, respiratory frequency and heart rate, however, without a significant influence on intraocular pressure or arterial blood pressure.

Influence of medetomidine, acepromazine, fentanyl and butorphanol on intraocular pressure and pupil size in healthy dogs

“…Medetomidine has been reported to decrease pupil diameter (Verbruggen et al 2000;Kanda et al 2015). These data are in agreement with our previous (Rauser et al 2016) and current findings.…”

“…Alpha-2 agonists have been reported to reduce IOP via a reduction of aqueous humour production, ciliary body vasoconstriction and a decrease in ciliary blood flow (Artigas et al 2012). We observed no changes in IOP after medetomidine administration, and our measurements are in agreement with those of our previous study (Rauser et al 2016). In contrast, these findings are not in agreement with those of Verbruggen et al (2000), where an increase in IOP in four dogs and a decrease in ten dogs five minutes after administration of medetomidine 0.15 mg/m 2 body surface area (corresponds to approximately 0.005 mg/kg) was reported.…”

Influence of capnoperitoneum on intraocular pressure in spontaneously breathing dogs undergoing ovariectomy

“…The study protocol was adopted and amended from previous studies comparing the influence of sedatives and anaesthetic drugs on IOP in dogs (Rauser et al 2012;Rauser et al 2016). All procedures were carried out with the consent of the Animal Welfare Ethics Committee of the University of Veterinary and Pharmaceutical Sciences, Brno, and all owners signed an informed consent before study enrolment.…”

Considerações à anestesia geral de cães e gatos com oftalmopatias

“…Foi observado que os midriáticos em associação com dexmedetomidina podem ser necessários para facilitar os procedimentos oftálmicos que exigem dilatação da pupila (Artigas, Redondo & Lopes-Murcia, 2012). Rauser, Mrazova & Zapletalova (2016) verificaram que o uso de dexmedetomidina ou medetomidina, por via intramuscular, associados com propofol e isoflurano resultou em miose, no entanto, sem uma redução significativa na pressão intraocular ou pressão arterial.…”