The Influence of Anaesthetic Drugs on the Laryngeal Motion in Dogs: A Systematic Review

Abstract

Anaesthetic drugs are commonly used during the evaluation of laryngeal function in dogs. The aim of this review was to systematically analyse the literature describing the effects of anaesthetic drugs and doxapram on laryngeal motion in dogs and to determine which drug regime provides the best conditions for laryngeal examination. PubMed, Google Scholar, and EMBASE databases were used for the literature search up to November 2019. Relevant search terms included laryngeal motion, anaesthetic drugs and dogs. Studies were scored based on their level of evidence (LoE), according to the Oxford Centre for Evidence-based Medicine, and the quality was assessed using the risk-of-bias tool and SIGN-checklist. In healthy dogs, premedication before laryngeal examination provided better examination conditions and maintained overall adequate laryngeal motion in 83% of the studies. No difference in laryngeal motion between induction drugs was found in 73% of the studies but the effects in dogs with laryngeal paralysis remain largely unknown. Doxapram increased laryngeal motion in healthy dogs without serious side effects, but intubation was necessary for some dogs with laryngeal paralysis. Methodological characteristics varied considerably between studies, including the technique and timing of evaluation, number of assessors, study design, drug dose, combinations, route and speed of administration.

Paralisia de laringe unilateral esquerda pós intubação em braquicefálico: Relato de caso

“…A sedação para realização do diagnóstico, independente da técnica a ser utilizada é de extrema importância pois uma sedação profunda pode interferir na funcionalidade das cartilagens aritenoides e induzir um diagnóstico falso positivo (Kitshoff et al, 2013;MacPhail, 2020;Ranninger et al, 2020). Levantamento realizado por Ranninger et al (2020) revelou não existir recomendação de protocolo anestésico único, entretanto mostrou que o uso de medicações pré-anestésicas contribuiu para manter o movimento laríngeo adequado considerando que a presença de medicações pré-anestésicas irá reduzir a dose dos medicamentos de indução. Associado à sedação leve a ser realizada, fármacos estimulantes do sistema respiratório como o doxapram (1 mg/kg IV) podem ser administrados para auxílio do diagnóstico, assim como leve estímulos mecânicos diretamente sobre as cartilagens (MacPhail, 2020;Ovbey et al, 2014;Ranninger et al, 2020).…”

“…Levantamento realizado por Ranninger et al (2020) revelou não existir recomendação de protocolo anestésico único, entretanto mostrou que o uso de medicações pré-anestésicas contribuiu para manter o movimento laríngeo adequado considerando que a presença de medicações pré-anestésicas irá reduzir a dose dos medicamentos de indução. Associado à sedação leve a ser realizada, fármacos estimulantes do sistema respiratório como o doxapram (1 mg/kg IV) podem ser administrados para auxílio do diagnóstico, assim como leve estímulos mecânicos diretamente sobre as cartilagens (MacPhail, 2020;Ovbey et al, 2014;Ranninger et al, 2020). No presente caso a sedação em ambos os momentos de laringoscopia direta ocorreu após indução anestésica sobre dose-efeito, posterior a administração de fármacos pré-anestésicos, condizente com o levantamento de Ranninger et al (2020) e demais estudos publicados (Ovbey et al, 2014).…”

Postoperative pharmacological ventilation in a dog following surgical stabilisation of the first and second cervical vertebrae

“…15 In veterinary medicine, doxapram is used to increase the rate and depth  of  of breathing when assessing laryngeal function in dogs. [16][17][18] Doxapram is also used in resuscitation of canine and feline neonates following dystocia and caesarean section, when ventilation needs to be stimulated. [19][20][21] In humans, adverse effects following doxapram administration include tachycardia, cardiac arrhythmias, hypertension and excitation.…”

Laryngeal function in normal dogs administered isoflurane following partial clearance of alfaxalone or propofol

“…The effects of anesthetics on laryngeal motion and ventilatory drive may affect accurate evaluation of laryngeal function (MacPhail 2020;Ranninger et al 2020). Observation of at least some degree of laryngeal paresis was reported as high as 25% in a population of 250 dogs undergoing general anesthesia for various indications (Broome et al 2000).…”

“…Observation of at least some degree of laryngeal paresis was reported as high as 25% in a population of 250 dogs undergoing general anesthesia for various indications (Broome et al 2000). Since that study, the influences of the induction anesthetic, dose and administration rates, use of premedicants and use of chemical or mechanical stimulants as part of a laryngeal function examination have been investigated (Gross et al 2002;Miller et al 2002;Jackson et al 2004;Tobias et al 2004;McKeirnan et al 2014;Smalle et al 2017;Ambros et al 2018;Norgate et al 2018;Radkey et al 2018;Brown et al 2019;Labuscagne et al 2019;DeGroot et al 2020;Ranninger et al 2020). To date, only drugs administered via intramuscular and intravenous (IV) routes have been investigated for laryngeal function examination.…”