RESUMO
OBJECTIVE: To evaluate the sedative and cardiopulmonary effects of various combinations of acepromazine, dexmedetomidine, hydromorphone, and glycopyrrolate, followed by anesthetic induction with propofol and maintenance with isoflurane in healthy dogs. ANIMALS: 6 healthy adult female Beagles. PROCEDURES: Dogs were instrumented for hemodynamic measurements while anesthetized with isoflurane. Two hours after recovery, dogs received 1 of 4 IM combinations in a crossover design with 1 week between treatments: hydromorphone (0.1 mg/kg) and acepromazine (0.005 mg/kg; HA); hydromorphone and dexmedetomidine (0.0025 mg/kg; HD); hydromorphone, acepromazine, and dexmedetomidine (HAD); and hydromorphone, acepromazine, dexmedetomidine, and glycopyrrolate (0.02 mg/kg; HADG). Sedation was scored after 30 minutes. Physiologic variables and cardiac index were measured after sedation, after anesthetic induction with propofol, and every 15 minutes during maintenance of anesthesia with isoflurane for 60 minutes (target expired concentration at 760 mm Hg, 1.3%). RESULTS: Sedation scores were not significantly different among treatments. Mean ± SD cardiac index was significantly higher for the HA (202 ± 45 mL/min/kg) and HADG (185 ± 59 mL/min/kg) treatments than for the HD (88 ± 31 mL/min/kg) and HAD (103 ± 25 mL/min/kg) treatments after sedation and through the first 15 minutes of isoflurane anesthesia. No ventricular arrhythmias were noted with any treatment. CLINICAL RELEVANCE: In healthy dogs, IM administration of HADG before propofol and isoflurane anesthesia provided acceptable cardiopulmonary function with no adverse effects. This combination should be considered for routine anesthetic premedication in healthy dogs.
Assuntos
Anestesia , Anestésicos , Dexmedetomidina , Isoflurano , Propofol , Acepromazina/farmacologia , Anestesia/veterinária , Anestésicos/farmacologia , Animais , Estudos Cross-Over , Dexmedetomidina/farmacologia , Cães , Feminino , Glicopirrolato/farmacologia , Frequência Cardíaca , Hidromorfona/farmacologia , Hipnóticos e Sedativos/farmacologia , Isoflurano/farmacologia , Propofol/farmacologiaRESUMO
OBJECTIVE: To evaluate the effects of butorphanol on cardiopulmonary parameters in dogs anesthetized with desflurane and breathing spontaneously. STUDY DESIGN: Prospective, randomized experimental trial. ANIMALS: Twenty dogs weighing 12 ± 3 kg. METHODS: Animals were distributed into two groups: a control group (CG) and butorphanol group (BG). Propofol was used for induction and anesthesia was maintained with desflurane (10%). Forty minutes after induction, the dogs in the CG received sodium chloride 0.9% (0.05 mL kg(-1) IM), and dogs in the BG received butorphanol (0.4 mg kg(-1) IM). The first measurements of body temperature (BT), heart rate (HR), arterial pressures (AP), cardiac output (CO), cardiac index (CI), central venous pressure (CVP), stroke volume index (SVI), pulmonary arterial occlusion pressure (PAOP), mean pulmonary arterial pressure (mPAP), left ventricular stroke work (LVSW), systemic (SVR) and pulmonary (PVR) vascular resistances, respiratory rate (f(R) ), and arterial oxygen (PaO(2) ) and carbon dioxide (PaCO(2) ) partial pressures were taken immediately before the administration of butorphanol or sodium chloride solution (T0) and then at 15-minute intervals (T15-T75). RESULTS: In the BG, HR, AP, mPAP and SVR decreased significantly from T15 to T75 compared to baseline. f(R) was lower at T30 than at T0 in the BG. AP and f(R) were significantly lower than in the CG from T15 to T75. PVR was lower in the BG than in the CG at T30, while PaCO(2) was higher compared with T0 from T30 to T75 in the BG and significantly higher than in the CG at T30 to T75. CONCLUSIONS AND CLINICAL RELEVANCE: At the studied dose, butorphanol caused hypotension and decreased ventilation during desflurane anesthesia in dogs. The hypotension (from 86 ± 10 to 64 ± 10 mmHg) is clinically relevant, despite the maintenance of cardiac index.
Assuntos
Analgésicos Opioides/farmacologia , Anestesia Geral/veterinária , Anestésicos Combinados/farmacologia , Anestésicos Inalatórios , Butorfanol/farmacologia , Hemodinâmica/efeitos dos fármacos , Isoflurano/análogos & derivados , Analgésicos Opioides/administração & dosagem , Anestesia Geral/métodos , Anestésicos Combinados/administração & dosagem , Anestésicos Inalatórios/administração & dosagem , Animais , Gasometria/veterinária , Pressão Sanguínea/efeitos dos fármacos , Butorfanol/administração & dosagem , Débito Cardíaco/efeitos dos fármacos , Desflurano , Cães , Feminino , Frequência Cardíaca/efeitos dos fármacos , Injeções Intramusculares/veterinária , Isoflurano/administração & dosagem , Masculino , Taxa Respiratória/efeitos dos fármacosRESUMO
OBJECTIVE: To determine the magnitude and duration of sevoflurane minimum alveolar concentration (MAC) reduction following a single intravenous (IV) dose of methadone in cats. STUDY DESIGN: Prospective experimental study. ANIMALS: Eight (four females and four males) healthy mixed-breed adult (1-2 years) cats weighing 5.82 ± 0.42 kg. METHODS: Anesthesia was induced and maintained with sevoflurane. Intravenous catheters facilitated administration of methadone and lactated Ringer's solution. After baseline MAC determination in triplicate using a tail clamp technique, 0.3 mg kg(-1) of methadone was administered IV. End-tidal sevoflurane concentration (e'SEVO) was reduced and MAC was redetermined. In an effort to determine the duration of MAC reduction, measurements were repeated in a stepwise manner until MAC values returned to baseline. After the last stimulation, the e'SEVO was increased to 1.2 individual MAC for 15 minutes, then sevoflurane was discontinued and cats were allowed to recover from anesthesia. RESULTS: Baseline sevoflurane MAC was 3.18 ± 0.06%. When compared with baseline the sevoflurane MAC after methadone administration was significantly reduced by 25, 15 and 7% at 26, 76 and 122 minutes, respectively. The final MAC value (3.09 ± 0.07%) determined 156 minutes after methadone administration was not significantly different from baseline. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous methadone (0.3 mg kg(-1)) significantly decreased MAC of sevoflurane in cats but the effect was short-lived.
Assuntos
Analgésicos Opioides/farmacologia , Anestesia por Inalação/veterinária , Anestésicos Inalatórios/farmacologia , Gatos , Metadona/farmacologia , Éteres Metílicos/farmacologia , Movimento/efeitos dos fármacos , Analgésicos Opioides/sangue , Período de Recuperação da Anestesia , Animais , Pressão Sanguínea/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Frequência Cardíaca/efeitos dos fármacos , Injeções Intravenosas/veterinária , Masculino , Metadona/sangue , Estudos Prospectivos , Alvéolos Pulmonares , Sevoflurano , Fatores de TempoRESUMO
OBJECTIVES: To investigate the effects of levomepromazine and different desflurane concentrations upon electrocardiographic variables. ANIMALS: Twenty adult mongrel dogs of both sexes weighing 6-28 kg. METHODS: Dogs were divided into two groups of 10 animals. Group 1 received 1 mg kg(-1) i.v. of levomepromazine and 15 minutes later anesthesia was induced with propofol (3 mg kg(-1) i.v.). Desflurane end-tidal concentration was set at 1.6 MAC. After 30 minutes at this concentration, measurements were taken and the end-tidal concentration was reduced to 1.4 MAC. Thereafter, it was reduced to 1.2 and then 1.0 MAC at 15-minute intervals. The same procedure was followed for group 2, except that levomepromazine was replaced with 0.2 mL kg(-1) of 0.9% saline solution and more propofol was needed for induction (7 mg kg(-1)). The animals' body temperature was maintained between 38.3 and 39 degrees C using a heating pad. The electrocardiographic tracing was obtained from lead II throughout the experimental period. The measurements were taken immediately before the administration of levomepromazine or placebo (T1), 15 minutes after pre-medication (T2) and 30 minutes after the establishment of 1.6 MAC (T3). The other measurements were made at the concentrations of 1.4, 1.2, and 1.0 MAC, respectively (T(4-6)). The numerical data were submitted to analysis of variance plus F-test (p<0.05). RESULTS: The dogs that received levomepromazine had a decrease in heart rate. However, in both groups it increased with desflurane administration. Levomepromazine, in association with desflurane, did not induce significant electrocardiographic changes, and all mean values (except P-wave duration) were within the reference range for this species. CONCLUSIONS AND CLINICAL RELEVANCE: This study documented that levomepromazine, in association with desflurane, does not induce significant changes in electrocardiographic variables, suggesting that this drug combination has minimal effect on myocardial conduction.