Parametric evaluation of methotrimeprazine-midazolam-ketamine and methotrimeprazine-midazolam-ketamine-xylazine combination in dogs

Abstract

Purpose:To evaluate the parameters of dogs anesthetized by different dissociative drugs protocols through continuous intravenous infusion. Methods: Thirty healthy dogs of both sexes were assigned randomly to three groups (G1, G2, and G3). G1 was administered with methotrimeprazine as a pre-anesthetic medication, intravenously midazolam-ketamine as bolus for induction and midazolam-ketamine by continuous intravenous infusion for a 60 minute-period of maintenance. G2: the same as for G1. plus an increase in the midazolam dose during maintenance. G3: the same treatment as for G2, plus the addition of xylazine during maintenance. Immediately after induction the anesthetic maintenance started, and measures were taken 15 minutes after pre-medication, at 10 minutes intervals, during maintenance (M0 to M7). Results: Bradycardia, atrioventricular blockage, bradypnea and hypoxemia were shown in G3. G1 and G2 showed a slight hypotension only. Conclusion: There were some advantages by using the continuous intravenous via: no parameters oscillation and reduction in the anesthetic recovery period. The increase in midazolam dose brought about little parametric variations which were greater when xylazine was used, with a consequent hypoxemia, bradyarrhytmia, and decrease in respiratory frequency and minute volume. Key words: Anesthesia. Methotrimeprazine. Midazolam. Xylazine. Dogs. RESUMOObjetivo: Avaliar os parâmetros de cães anestesiados com diferentes protocolos de fármacos dissociativos por infusão intravenosa contínua. Métodos: Foram utilizados 30 cães, machos e fêmeas, clinicamente sadios, distribuídos aleatoriamente em três grupos (G1,G2 e G3) (*)). Em G1 utilizou-se levomepromazina como medicação pré-anestésica (MPA), midazolamcetamina pela via intravenosa em bolus para indução e midazolam-cetamina em infusão intravenosa contínua por 60 minutos para manutenção. Em G2 procedeu-se da mesma forma que em G1 elevando-se, porém, a dose de midazolam durante a manutenção. Em G3 repetiu-se o tratamento empregado em G2, acrescentando-se a xilazina à manutenção. Após a indução, iniciou-se imediatamente a manutenção anestésica, realizando-se aferições, 15 minutos depois da MPA, em intervalos de 10 minutos, durante a manutenção (M0 a M7). Resultados: Em G3 ocorreu bradicardia, bloqueio átrio-ventricular, bradipnéia e hipoxemia e em G1 e G2, discreta hipotensão. Conclusão: A via intravenosa contínua apresentou vantagens quanto a: não oscilação dos parâmetros e redução no período de recuperação anestésica. A elevação da dose de midazolam resultou em discretas variações paramétricas, estas, acentuadas pelo uso da xilazina, que causou hipoxemia, bradiarritmia, diminuição da freqüência respiratória e volume minuto.

Hemodynamics and bispectral index (BIS) of dogs anesthetized with midazolam and ketamine associated with medetomidine or dexmedetomidine and submitted to ovariohysterectomy

“…In the present study, both the anesthetic recovery period and its characteristics were similar in both groups and also similar to what has been reported in the literature 1,2 . One of the limitations of this study is the short infusion period of the proposed combinations, since the surgical procedure was performed in a short period of time.…”

“…Body temperature had a slight decrease in both groups, but with no significant difference or clinical relevance, similar to what was observed in another study on these drugs 1 . In the present study, both the anesthetic recovery period and its characteristics were similar in both groups and also similar to what has been reported in the literature 1,2 .…”

“…The administration of anesthetic agents by continuous venous infusion reduces oscillations in their plasma concentration, the risk of over or under dosing and decreases total anesthetic agents consumption. Some commonly used drugs, such as xylazine and medetomidine, may cause adverse hemodynamic effects when administered as a bolus, while the administration by continuous infusion provides good cardiovascular stability 1,2 . Dexmedetomidine, the pharmacologically active isomer of medetomidine, has been used in continuous infusion during anesthetic and surgical procedures in humans.…”

Continuous infusion in adult females dogs submitted to ovariohysterectomy with midazolam-xylazine and/or medetomidine pre-treated with methotrimeprazine and buprenorphine

“…A shorter anesthetic recovery period occurred in G2 (48 min) as compared to G1 (52 min) and, also with a superior quality. o C what has also been reported for different dissociative anesthesia protocols through continuous infusion 2,3,4 .A greater reduction in body temperature as observed by some authors 5,6,7 is due to the peripheral vasoconstriction and blood central redistribution due to the action of a-2 agonists. This is a controversial effect for a-2 agonists lead to peripheral vasodilatation and heat production reduction.…”

Avaliação hemodinâmica e do índice bispectral (BIS) de cadela anestesiadas com midazolam e cetamina associados à medetomidina ou dexmedetomidina e submetidos a ovário-salpingo-histeectomia

“…A combinação dos bloqueios do sistema nervoso simpático e do parassimpático produziu redução moderada da pressão arterial média sem interferir com a frequência cardíaca e diminuiu a um valor quase indeterminável no plasma as O período para assumir a postura quadrupedal foi similar entre os grupos e semelhante ao observado por outros autores com o emprego da dexmedetomidina (5,6,101,102). O mesmo ocorreu com as características da recuperação anestésica, que foram isentas de efeitos adversos ou intranquilos, como observado em outros estudos anteriores (6,46,101).…”