Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Background Arterial hypoxaemia is common in anaesthetised horses, but little information exists regarding restoration of arterial oxygen tension (PaO2) during recovery from anaesthesia, or if intra‐operative management factors exert any longer‐term effect. Objectives To evaluate PaO2 in horses recovering from general anaesthesia up to 1 h after resuming standing. Study design Prospective observational clinical cohort study. Methods Systemically healthy adult horses undergoing inhalational general anaesthesia for elective surgical procedures were studied. Arterial blood samples were obtained anaerobically prior to pre‐anaesthetic medication, at end of anaesthesia, immediately following positioning in the recovery box, then at 10‐min intervals until standing. Additionally, samples were taken when horses achieved sternal recumbency, at standing (STAND) and 1 h after standing (STAND+1). Data were analysed using ANOVA and mixed‐effects linear regression, with significance set at P<0.05. Results Data from one hundred and two horses were analysed. Forty horses received controlled mandatory ventilation (CMV) throughout anaesthesia, 47 breathed spontaneously (SV) and 15 initially breathed spontaneously before CMV was imposed (S‐CMV). Overall, PaO2, P(A‐a)O2 and PaCO2 remained significantly lower than baseline at STAND+1 (P<0.01). CMV resulted in higher PaO2 at the end of anaesthesia (P = 0.03) and during early recovery (P<0.01) than SV. Only in group S‐CMV did PaO2, P(A‐a)O2 and PaCO2 return to baseline values at STAND+1. Highest PaO2 values associated with CMV were also associated with early recovery apnoea. Main limitations Non‐standardised anaesthetic management, temporal and quantitative variation in oxygen delivery during early recovery and lack of control group where oxygen was electively withheld during recovery. Conclusions Controlled mandatory ventilation results in better pulmonary function in horses as assessed by PaO2, P(A‐a)O2 and PaCO2, an effect enhanced by an initial period of SV and still evident 1 h after standing. High PaO2 values may contribute to early recovery apnoea but this does not adversely affect outcome

Hemogasometria e variáveis cardiopulmonares após administração do butorfanol em cães anestesiados pelo desfluorano sob ventilação espontânea Acid-base and cardiopulmonary effects after butorphanol administration in spontaneously breathing dogs anesthetized by desflurane

Este experimento teve por objetivos avaliar as possíveis alterações cardiopulmonares e hemogasométricas decorrentes do uso do butorfanol em cães submetidos à anestesia pelo desfluorano sob ventilação espontânea. Para tal, foram utilizados vinte cães adultos, clinicamente saudáveis, pesando 12&plusmn;3kg. Os animais foram distribuídos igualmente em dois grupos, GS e GB, e induzidos à anestesia com propofol (8,4&plusmn;0,8mg kg-1, IV), intubados e submetidos à anestesia inalatória pelo desfluorano (10V%). Decorridos 40 minutos da indução, foi administrado aos animais do GS 0,05mL kg-1 de solução fisiológica a 0,9% (salina), enquanto que, no GB, foi aplicado butorfanol na dose de 0,4mg kg-1, ambos pela via intramuscular. As observações das variáveis freqüências cardíaca (FC) e respiratória (f), pressões arteriais sistólica (PAS), diastólica (PAD) e média (PAM), pH arterial (pH), pressão parcial de oxigênio no sangue arterial (PaO2), pressão parcial de dióxido de carbono no sangue arterial (PaCO2), déficit de base (DB), bicarbonato (HCO3) e saturação de oxigênio na hemoglobina (SatO2) tiveram início imediatamente antes da aplicação do opióide ou salina (M0). Novas mensurações foram realizadas 15 minutos após a administração do butorfanol ou salina (M15) e as demais colheitas foram realizadas a intervalos de 15 minutos, por um período de 60 minutos (M30, M45, M60 e M75). Os dados numéricos dessas variáveis foram submetidos à Análise de Perfil (P<0,05). A freqüência cardíaca apresentou alteração no GB, com média de M0 maior que as demais. As PAS, PAD e PAM, assim como a f e o pH, apresentaram valores menores após a administração do opióide no GB, em comparação ao GS. A PaO2 apresentou discretas alterações, entretanto sem significado clínico, enquanto que a PaCO2 e o DB apresentaram valores de M0 menores que os demais após a aplicação do butorfanol. Os resultados obtidos permitem concluir que a administração do butorfanol em cães submetidos à anestesia pelo desfluorano, sob ventilação espontânea, reduz a freqüência cardíaca e a pressão arterial e promove certo grau de hipoventilação.<br>The cardiopulmonary and acid-base effects of butorphanol in desflurane anesthetized dogs breathing spontaneously were evaluated. Twenty adult healthy, male and female dogs were used. They were separated into two groups of 10 animals each (GS and GB). Anesthesia was induced with propofol (8.4&plusmn;0.8mg kg-1 IV) and maintained with desflurane (10V%). After 40 minutes of induction, the animals from GS received saline solution at 0.9% (0.05mL kg-1) and from GB received butorphanol (0.4mg kg-1), both applied intramuscularly. Heart (HR) and respiratory (RR) rates; systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures; arterial blood pH (pH), arterial partial pressure of O2 (PaO2) and arterial partial pressure of CO2 (PaCO2); base deficit (BD), arterial oxygen saturation (SaO2) and bicarbonate ion concentration (HCO3) were measured. The measurements were taken immediately before the application of the agents (M0). Serial measurements were carried out at 15 minutes intervals after the administration of butorphanol or saline up to 75 minutes (M15, M30, M45, M60 and M75). Data were submitted to Profile Analysis (P<0.05). After butorphanol administration HR, SAP, DAP and MAP decreased significantly. PaO2 had discreet alterations, however without clinical meaning. RR and pH decreased after butorphanol administration while PaCO2 increased significantly. It was possible to conclude that butorphanol administration in desflurane anesthetized dogs produced reduction in the averages of heart rate and arterial pressure and relatively to the respiratory parameters, the opioid produced hypoventilation in spontaneously breathing dogs

ADMINISTRAÇÃO EPIDURAL DE OPIÓIDES EM CÃES EPIDURAL OPIOIDS ADMINISTRATION IN DOGS

Os opióides têm sido utilizados em Medicina Veterinária há vários anos como alternativa para o alívio da dor pós-operatória ou traumática. Atualmente, tem-se dado maior valor ao controle da dor nos animais, visando a oferecer melhores condições de recuperação ao paciente traumatizado ou recém-operado. A morfina foi o primeiro opióide usado em animais. Mais recentemente, a administração dessa substância, por via epidural, vem sendo empregada no controle da dor com resultados promissores. Assim, nesta revisão, abordam-se vários aspectos referentes aos efeitos e às indicações da administração epidural de opióides em cães.<br>Opioids have been used for several years to relieve traumatic pain in Veterinary Medicine. The painful stimulus are implicated with delayed tissue recuperation of surgical wounds. Today, a great importance has been given to pre-emptive control of post operative pain in animals. Indeed, the use of epidural morphine, the first opioid substance used in animals, has provided excellent analgesia and good condition at the immediate post operative period. In addition, several aspects concerning the effects indications and forms of epidural opioids injections in dogs are considered in this review