O sevofluorano em cadelas gestantes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uso de dexmedetomidina em anestesiologia

JUSTIFICATIVA E OBJETIVOS: A dexmedetomidina é um novo agonista alfa2-adrenérgico que apresenta relação de seletividade entre os receptores alfa2:alfa1 de 1600:1, com importante ação sedativa e analgésica, bom controle hemodinâmico frente ao estresse e que pode produzir, por si só, anestesia. Este agente tem sido empregado para promover analgesia e sedação no período pós-operatório e nas unidades de tratamento intensivo. Devido à suas propriedades, recentemente, a dexmedetomidina passou a ser utilizada também na sala de operações, como fármaco coadjuvante em anestesia. Assim, este artigo faz uma revisão da literatura com relação ao uso da dexmedetomidina na prática anestésica. CONTEÚDO: São apresentados os principais trabalhos com o emprego da dexmedetomidina em Anestesiologia, seja como medicação pré-anestésica, ou durante o ato anestésico-cirúrgico. O mecanismo de ação dos fármacos alfa2-agonistas e as propriedades farmacocinéticas e farmacodinâmicas da dexmedetomidina também são revistos neste artigo. CONCLUSÕES: O uso da dexmedetomidina como medicação pré-anestésica, durante anestesia, ou no período pós-operatório, promove boa estabilidade hemodinâmica. Há redução do consumo de anestésicos durante a anestesia. Os pacientes sedados com a dexmedetomidina podem ser despertados, quando solicitados, e tornarem-se cooperativos. Mesmo doses elevadas do fármaco não provocam depressão respiratória. Bradicardia é um efeito adverso observado com freqüência, problema amenizado pela administração lenta da droga. Assim, a dexmedetomidina torna-se importante recurso adicional para a prática clínica da Anestesiologia, com possibilidade de uso em diversos tipos de pacientes e procedimentos cirúrgicos.

Efeitos da metadona ou do neostigmine, associados à lidocaína administrados pela via epidural em cães

Seis cães adultos, de raças e sexos variados, com peso de 13,3±3,4kg (média±DP), foram utilizados no estudo. Os animais foram tranqüilizados com acepromazina (0,1mg/kg, IV) e, após 30 minutos, foram aleatoriamente submetidos à anestesia epidural com um dos seguintes tratamentos: lidocaína 2% 0,25ml/kg (controle); neostigmine 0,01mg/kg+lidocaína (NEO); metadona 0,3mg/kg+lidocaína (MET). Todos os animais foram submetidos aos três tratamentos com intervalo mínimo de uma semana. Foram mensuradas as freqüências cardíaca (FC) e respiratória (FR), a pressão arterial sistólica (PAS), o tempo para a perda do reflexo interdigital, a duração e a altura do bloqueio sensitivo, durante um período de 90 minutos. Não houve diferença significativa entre os tratamentos nos valores de FC, PAS e FR, bem como na duração do bloqueio sensitivo e no tempo para a perda do reflexo interdigital. No grupo MET, houve diminuição de FC dos 30 aos 90 minutos em relação ao valor basal. Bloqueio sensitivo mais cranial também foi observado em MET. A associação de neostigmine ou metadona não prolongou o período hábil de anestesia epidural produzido pela lidocaína em cães. A metadona, mas não o neostigmine, parece estender mais cranialmente o bloqueio epidural pela lidocaína.

Ventilação mandatória intermitente sincronizada versus ventilação com suporte pressórico e volume garantido em coelhos induzidos à hemorragia aguda

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Levomepromazina e atropina como medicações pré-anestésicas na anestesia pela associação tiletamina/zolazepam, em cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anestesia epidural cranial com lidocaína e morfina para campanhas de castração em cães

A castração de machos e fêmeas tem sido preconizada como a principal técnica para redução do grande número de cães errantes. No entanto, vários são os entraves com relação à escolha do melhor protocolo anestésico, em relação à eficácia, segurança e redução de custos. Objetivou-se, com este trabalho, avaliar os efeitos cardiorrespiratórios, hemogasométricos e analgésicos da utilização de lidocaína em um volume maior, associada à morfina, pela via epidural em cadelas submetidas à ovariosalpingohisterectomia (OSH), com ou sem suplementação de oxigênio. Utilizaram-se 12 cadelas, com peso médio de 11,5±3,7kg e idade de um a quatro anos. Os animais receberam como medicação pré-anestésica (MPA) acepromazina (0,1mg kg-1) e meperidina (5mg kg-1), pela via intramuscular. Após 15 minutos, administrou-se tiopental (10mg kg-1), por via intravenosa, seguido de intubação endotraqueal. Nesse momento, os animais foram alocados em dois grupos: o grupo GCO (com oxigênio, n=06) recebeu suplementação de oxigênio 100% e o grupo GSO (sem oxigênio, n=06) permaneceu intubado sem suplementação de oxigênio. Após a intubação, foi administrada, pela via epidural, em ambos os grupos, morfina (0,1mg kg-1) em volume final ajustado para 1mL 3,0kg-1 de peso com lidocaína 2% sem vasoconstritor. Imediatamente após a anestesia epidural, os animais foram posicionados em decúbito dorsal com a cabeça no mesmo plano do corpo, e iniciou-se o procedimento cirúrgico, o qual foi padronizado em 30 minutos. em ambos os grupos, foi possível realizar a cirurgia sem a necessidade de complementação analgésica e sem resposta de dor. A pressão arterial média (PAM) foi menor no GSO em todos os momentos em comparação ao basal. No GCO, a PAM foi menor após MPA e após epidural. Houve redução da f de M1 até M6 no GSO. A SaO2 e PaO2 foram maiores no GCO em comparação ao GSO. O pH foi menor no GCO 15 minutos após MPA até 40 minutos após epidural, em comparação ao GSO. Conclui-se que a anestesia epidural lombossacra com morfina e lidocaína na dose e no volume propostos é efetiva para realização de OSH em cadelas, com mínimas alterações cardiovasculares e hemogasométricas, as quais são bem toleradas em animais hígidos. Essa prática é exequível em campanhas de castração em que não há possibilidade de oxigenação dos animais.

Midazolam and ketamine induction before halothane anaesthesia in ponies: cardiorespiratory, endocrine and metabolic changes

Six Welsh gelding ponies were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) prior to induction of anaesthesia with midazolam at 0.2 mg/kg and ketamine at 2 mg/kg i.v.. Anaesthesia was maintained for 2 h using 1.2% halothane concentration in oxygen. Heart rate, electrocardiograph (EGG), arterial blood pressure, respiratory rate, blood gases, temperature, haematocrit, plasma arginine vasopressin (AVP), dynorphin, beta-endorphin, adrenocorticotropic hormone (ACTH), cortisol, dopamine, noradrenaline, adrenaline, glucose and lactate concentrations were measured before and after premedication, immediately after induction, every 20 min during anaesthesia, and at 20 and 120 min after disconnection. Induction was rapid, excitement-free and good muscle relaxation was observed. There were no changes in heart and respiratory rates, Decrease in temperature, hyperoxia and respiratory acidosis developed during anaesthesia and slight hypotension was observed (minimum value 76 +/- 10 mm Hg at 40 mins), No changes were observed in dynorphin, beta-endorphin, ACTH, catecholamines and glucose, Plasma cortisol concentration increased from 220 +/- 17 basal to 354 +/- 22 nmol/L at 120 min during anaesthesia; plasma AVP concentration increased from 3 +/- 1 basal to 346 +/- 64 pmol/L at 100 min during anaesthesia and plasma lactate concentration increased from 1.22 +/- 0.08 basal to 1.76 +/- 0.13 mmol/L at 80 min during anaesthesia, Recovery was rapid and uneventful with ponies taking 46 +/- 6 min to stand. When midazolam/ketamine was compared with thiopentone or detomidine/ketamine for induction before halothane anaesthesia using an otherwise similar protocol in the same ponies, it caused slightly more respiratory depression, but less hypotension. Additionally, midazolam reduced the hormonal stress response commonly observed during halothane anaesthesia and appears to have a good potential for use in horses.

Evaluation of the isoflurane-sparing effects of lidocaine and fentanyl during surgery in dogs

Objective-To evaluate the isoflurane-sparing effects of lidocaine and fentanyl administered by constant rate infusion (CRI) during surgery in dogs.Design-Randomized prospective study.Animals-24 female dogs undergoing unilateral mastectomy because of mammary neoplasia.Procedures-After premedication with acepromazine and morphine and anesthetic induction with ketamine and diazepam, anesthesia in dogs (n = 8/group) was maintained with isoflurane combined with either saline (0.9% NaCl) solution (control), liclocaine (1.5 mg/kg [0.68 mg/lb], IV bolus, followed by 250 mu g/kg/min [113 mu g/lb/min], CRI), or fentanyl (5 mu g/kg [2.27 mu g/lb], IV bolus, followed by 0.5 mu g/kg/min [0.23 mu g/lb/min], CRI). Positive-pressure ventilation was used to maintain eucapnia. An anesthetist unaware of treatment, endtidal isoflurane (ETiso) concentration, and vaporizer concentrations adjusted a nonprecision vaporizer to maintain surgical depth of anesthesia. Cardiopulmonary variables and ETiso values were monitored before and after beginning surgery.Results-Heart rate was lower in the fentanyl group. Mean arterial pressure did not differ among groups after surgery commenced. In the control group, mean +/- SD ETiso values ranged from 1.16 +/- 0.35% to 1.94 +/- 0.96%. Fentanyl significantly reduced isoflurane requirements during surgical stimulation by 54% to 66%, whereas the reduction in ETiso concentration (34% to 44%) observed in the lidocaine group was not significant.Conclusions and Clinical Relevance-Administration of fentanyl resulted in greater isoflurane sparing effect than did liclocaine. However, it appeared that the low heart rate induced by fentanyl may partially offset the improvement in mean arterial pressure that would be expected with reduced isoflurane requirements.

Effects of acepromazine on the cardiovascular actions of dopamine in anesthetized dogs

To evaluate the effects of acepromazine maleate on the cardiovascular changes induced by dopamine in isoflurane-anesthetized dogs.Prospective, randomized cross-over experimental design.Six healthy adult spayed female dogs weighing 16.4 +/- 3.5 kg (mean +/- SD).Each dog received two treatments, at least 1 week apart. Acepromazine (0.03 mg kg(-1), IV) was administered 15 minutes before anesthesia was induced with propofol (7 mg kg(-1), IV) and maintained with isoflurane (1.8% end-tidal). Acepromazine was not administered in the control treatment. Baseline cardiopulmonary parameters were measured 90 minutes after induction. Thereafter, dopamine was administered intravenously at 5, 10, and 15 mu g kg(-1) minute(-1), with each infusion rate lasting 30 minutes. Cardiopulmonary data were obtained at the end of each infusion rate.Dopamine induced dose-related increases in cardiac index (CI), stroke index, arterial blood pressure, mean pulmonary arterial pressure, oxygen delivery index (DO2I) and oxygen consumption index. In the control treatment, systemic vascular resistance index (SVRI) decreased during administration of 5 and 10 mu g kg(-1) minute(-1) of dopamine and returned to baseline with the highest dose (15 mu g kg (-1) minute(-1)). After acepromazine treatment, SVRI decreased from baseline during dopamine administration, regardless of the infusion rate, and this resulted in a smaller increase in blood pressure at 15 mu g kg (-1) minute(-1). During dopamine infusion hemoglobin concentrations were lower following acepromazine and this contributed to significantly lower arterial O-2 content.Acepromazine prevented the return in SVRI to baseline and reduced the magnitude of the increase in arterial pressure induced by higher doses of dopamine. However, reduced SRVI associated with lower doses of dopamine and the ability of dopamine to increase CI and DO2I were not modified by acepromazine premedication.Previous acepromazine administration reduces the efficacy of dopamine as a vasopressor agent in isoflurane anesthetized dogs. Other beneficial effects of dopamine such as increased CO are not modified by acepromazine.

Evaluation of intraocular pressure in association with cardiovascular parameters in normocapnic dogs anesthetized with sevoflurane and desflurane

The objective of this study was to determine intraocular pressure (IOP) and cardiac changes in normocapnic dogs maintained under controlled ventilation and anesthetized using sevoflurane or desflurane. Sixteen healthy adult mixed-breed dogs, seven males and nine females, weighing 10-15 kg were used. The dogs were randomly assigned to one of two groups composed of eight animals anesthetized with sevoflurane (SEVO) or desflurane (DESF). In both groups, anesthesia was induced with propofol (10 mg/kg), and neuromuscular blockade was achieved with rocuronium (0.6 mg/kg/h IV). No premedication was given. Ventilation was adjusted to maintain end-tidal carbon dioxide partial pressure at 35 mmHg. Anesthesia was maintained with 1.5 minimum alveolar concentration (MAC) of sevoflurane or desflurane. In both groups IOP was measured by applanation tonometry (Tono-Pen) before induction of anesthesia. IOP, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI) and central venous pressure (CVP) were also measured 45 min after the beginning of inhalant anesthesia and then every 20 min for 60 min. A one-way repeated measures ANOVA was used to compare data within the same group and Student's t-test was used to assess differences between groups. P < 0.05 was considered statistically significant. Measurements showed normal IOP values in both groups, even though IOP increased significantly from baseline during the use of desflurane. IOP did not differ between groups. CI in the desflurane group was significantly greater than in the sevoflurane group. Sevoflurane and desflurane have no clinically significant effects on IOP, MAP, HR, CI or VCP in the dog.

Evaluation of cardiorespiratory effects of combinations of dexmedetomidine and atropine in cats

The cardiovascular effects of dexmedetomidine alone or in combination with atropine were studied in six cats. Cats underwent four treatments in a randomized crossover design as follows: DEX15, saline + dexmedetomidine 15 mu g/kg; DEX30, saline + dexmedetomidine 30 mu g/kg; ADEX15, atropine + dexmedetomidine 15 mu g/kg; ADEX30, atropine + dexmedetomidine 30 mu g/kg. Pulse rate (PR) and systolic arterial pressure (SAP) decreased in DEX15 and DEX30. Premedication with atropine was effective in preventing bradycardia (PR < 100 beats/min) and resulted in a biphasic effect in blood pressure. Hypertension was followed by a gradual decrease in SAP. Rate pressure product decreased in DEX15 and DEX30 whereas in ADEX15 and ADEX30 it remained within baseline values for at least 60 min. Although premedication with atropine in cats sedated with dexmedetomidine prevents bradycardia, it induces hypertension and increases myocardial oxygen consumption. The magnitude of cardiovascular effects produced by dexmedetomidine in cats does not seem to be dose-related. (C) 2009 ESFM and AAFP. Published by Elsevier Ltd. All rights reserved.

SUFENTANIL INTRANASAL COME MEDICACAO PRE-ANESTESICA EM CRIANCAS

Background and objectives: Among the different routes used for the administration of preoperative medication, the intranasal route offers the advantage of a rapid systemic absorption as well as the avoidance of painful intramuscular and intravenous injections. The aim of the present study is to evaluate the efficacy of sufentanil as a preoperative medication for the reduction of anxiety in pediatric patients in addition to its effects on the children's behaviour during the induction of anesthesia. Methods - Thirty patients whose ages ranged from 1 to 9 years old, physical status ASA 1, submitted to elective surgeries participated in the study and received sufentanil (2 μg.kg-1) by the intranasal route as preoperative medication. Using the modified Doughty index, the anxiety level was evaluated at 3 moments: To upon arrival of the child with parents: T5 and T10, five and ten minutes after the administration of the drug respectively. Behaviour during the induction of anesthesia was also evaluated. Induction of anesthesia was performed thiopental or ketamine. Results - The level of anxiety was not lower ten minutes after the administration of sufentanil and no improvement in the quality of the anesthetic induction was observed. Conclusions - Intranasal sufentanil in the doses used in this study did not prove to be efficient in the reduction of the anxiety level nor did it improve the quality of the induction of anesthesia when the period between the drug administration and separation from the parents was only ten minutes.

Peridural com ropivacaina a 1%: Experiencia com volume proporcional a estatura

Background and Objectives - Ropivacaine - a local amino amide anesthetic agent - is a plain S enantiomer which makes it a potent and low toxicity drug. The aim of our study was to evaluate 1% ropivacaine for epidural block in lower doses than those described in the literature. Methods - Thirty-eight patients, physical status ASA I and II, aged 15 to 70 years, weighing 50 to 100 kg were selected. Premedication consisted of 15 mg oral midazolam given 60 min before anesthesia induction. In the OR, after standard monitoring a catheter was inserted intravenously to administer 10 ml.kg-1 Ringers lactate solution. Epidural puncture was performed with the patient in the sitting position and 1% ropivacaine was administered in a volume corresponding to 10% of patient's height in centimeters. With the patient in the supine position, motor blockade intensity, temperature sensitivity and sensory block extension at 1, 3, 5, 7, 10, 15, 20, 30 minutes after drug injection were evaluated. Blood pressure, heart rate and adverse side effects during the course of anesthesia and in the post-anesthetic period were also observed. In the recovery room patients were followed-up until motor blockade intensity temperature sensitivity and sensory block had returned to level L2. Results - Mean values were 41.4 years of age, 68.8 kg of body weight and 165 cm height. Upper thermal blockade level was T4 and upper sensory block level was T6. Most patients showed motor block level 1 (Bromage scale) after 30 minutes of observation. Motor block mean duration was 254 minutes and temperature sensitivity 426 minutes. Only three patients had complications: two cases of hypotension and one of bradycardia. Conclusions - In the volumes used in this study, ropivacaine produced adequate analgesia and a less intense lower limb motor block which, however, was sufficient to allow for surgical procedures with low incidence of side-effects.