Dexmedetomidine combined with etomidate or emulsified isoflurane for induction reduced cardiopulmonary response in dogs.

Chao Liu,Zhenlei Zhou,Tingting Lin,Francesco Staffieri

doi:10.1371/journal.pone.0208625

Abstract

To investigate the effects of etomidate, emulsified isoflurane, and their combination with dexmedetomidine on physiological parameters, electrocardiogram (ECG) results, and the quality of induction and recovery during isoflurane maintenance anaesthesia. 5 mixed-breed dogs received each of four treatments: etomidate (E group); emulsified isoflurane (EI group); both dexmedetomidine and etomidate (DE group); or both dexmedetomidine and emulsified isoflurane (DEI group). All drugs were IV injection administered for induction, followed by 1.5 MAC (minimal alveolar concentration) of isoflurane to maintain anaesthesia. Rectal temperature (RT), respiratory rate (RR), heart rate (HR), mean arterial pressure (MAP), and ECG were measured at baseline, 0, 5, 10, 20, 40, and 60 minutes after intubation. The quality of induction and recovery was evaluated for all dogs. All the anaesthetic procedures provided good conditions for induction of anaesthesia. The quality of induction and recovery in the E group was worse than other groups. The decrease of RR in the E and DE groups was stronger than that in the EI and DEI groups. The dogs in the E group had the most significant prolongation of the Q-T interval and changes in the S-T segment. Deviation and extension of the S-T segment were noted in the El group. The dogs in the DE and DEI groups had fewer changes in the ECG results than those in the E and EI groups. The addition of dexmedetomidine caused less effect on cardiopulmonary parameters and the ECG results than either etomidate or emulsified isoflurane alone. Thus, etomidate or emulsified isoflurane in combination with dexmedetomidine may be useful clinically for the induction of anaesthesia.

Highlights

Isoflurane is commonly used as an inhalation anaesthetic in the veterinary clinic; it is considered safe for the cardiovascular system and has little influence on hepatic metabolism [1]
The values are presented as mean ± standard deviation. a Significantly different from E group (P
The time of extubation and the time to raise the head was significantly longer in the DE group than in the E, EI, and DEI groups (P

Summary

Introduction

Isoflurane is commonly used as an inhalation anaesthetic in the veterinary clinic; it is considered safe for the cardiovascular system and has little influence on hepatic metabolism [1]. The most prominent adverse effect during isoflurane anaesthesia is respiratory depression, which can result in hypercapnia and acidosis because of decreased respiration rate [2]. Α-2 agonists, dissociative anaesthetics, and diazepam were used in dogs as a single drug treatment. Combined anaesthesia in dogs or as part of pre-anaesthetic drug combinations to provide analgesia and to reduce the adverse effects and the amount of isoflurane anaesthetic required [3, 4]. Dexmedetomidine, an α-2 adrenergic receptor agonist, can provide sedative, analgesic, and anti-anxiety effects [5]. It has been reported that dexmedetomidine has bronchoprotective effects and reduces oxygen consumption, carbon dioxide production, and energy consumption [7, 8]. The disadvantages of dexmedetomidine treatment include bradycardia, hypotension, nausea, and dryness of mouth [9]

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