Adrenomedullin induces pulmonary vasodilation but does not attenuate pulmonary hypertension in a sheep model of acute pulmonary embolism.

AIMS: The pulmonary vasodilation induced by adrenomedullin may be beneficial in the acute pulmonary embolism (APE) setting. This study examined effects of adrenomedullin in sheep with microsphere-induced APE. MAIN METHODS: Twenty four anesthetized, mechanically ventilated sheep were randomly assigned into 3 groups (n=8 per group): animals not subjected to any intervention (Sham), animals with APE induced by microspheres (500 mg, intravenously) treated 30 min later by intravenous physiological saline (Emb group) or intravenous adrenomedullin (50 ng/kg/min) during 30 min (Emb+Adm group). Plasma concentrations of cyclic adenosine (cAMP) and guanosine monophosphate (cGMP) were determined by enzyme immunoassay. KEY FINDINGS: Variables did not change over time in sham animals. In both embolized groups, microsphere injection significantly (P<0.05) increased pulmonary vascular resistance index (PVRI) and mean pulmonary artery pressure (MPAP) from baseline by 181% and 111-142%, respectively (% change in mean values). Adrenomedullin significantly decreased PVRI (18%-25%) and significantly increased cardiac index (22%-25%) from values recorded 30 min after APE (E30), without modifying MPAP. Adrenomedullin decreased mean arterial pressure (18%-24%) and systemic vascular resistance index (32%-40%). Embolization significantly increased arterial-to-end tidal CO2 gradient, alveolar-to-arterial O2 gradient, and pulmonary shunt fraction from baseline, but these variables were unaffected by adrenomedullin. While adrenomedullin significantly increased plasma cAMP, cGMP levels were unaltered. SIGNIFICANCE: Adrenomedullin induces systemic and pulmonary vasodilation, possibly via a cAMP mediated mechanism, without modifying the gas exchange impairment associated with APE. The pulmonary anti-hypertensive effect of adrenomedullin may be offset by increases in cardiac index.

Analgesic comparison of systemic lidocaine, morphine or lidocaine plus morphine infusion in dogs undergoing fracture repair.

PURPOSE: To compare the postoperative analgesic effects of lidocaine, morphine and lidocaine plus morphine administered by constant rate infusion (CRI) and analyzing their effects on opioid requirements after orthopedic surgery in dogs. METHODS: Twenty-four dogs underwent fracture repairs were premedicated with IM acepromazine (0.05 mg/kg) combined with morphine (0.3mg/kg). Anesthesia was induced with IV propofol (4 to 5 mg/ kg) and maintained with isoflurane. The dogs were randomly assigned to 3 groups and administered a CRI IV of lidocaine (T-L), morphine (T-M) or lidocaine plus morphine (T-LM) at the same doses. Postoperative analgesia was assessed for 24 hours using a Visual Analog Scale (VAS) and the Glasgow Composite Pain Scale (GCPS). Rescue analgesia was performed if the evaluation score exceeded 50% of the VAS and/or 33% of the GCPS. RESULTS: The pain score and postoperative opioid requirements did not differ among the treatments. Rescue analgesia was administered to 1/8 dogs in the T-M and T-LM, and to 3/8 dogs in the T-L. CONCLUSION: Lidocaine, morphine or lidocaine/morphine CRI may be efficacious techniques for pain management in the first 24 hours post-surgery. However, the two drugs administered together did not reduce the postoperative opioid requirement in dogs undergoing fracture repair. Key words: Anesthesia. Analgesics. Analgesics, Opioid. Lidocaine. Morphine. Dogs.

Analgesic comparison of systemic lidocaine, morphine or lidocaine plus morphine infusion in dogs undergoing fracture repair

To compare the postoperative analgesic effects of lidocaine, morphine and lidocaine plus morphine administered by constant rate infusion (CRI) and analyzing their effects on opioid requirements after orthopedic surgery in dogs. Twenty-four dogs underwent fracture repairs were premedicated with IM acepromazine (0.05 mg/kg) combined with morphine (0.3mg/kg). Anesthesia was induced with IV propofol (4 to 5 mg/ kg) and maintained with isoflurane. The dogs were randomly assigned to 3 groups and administered a CRI IV of lidocaine (T-L), morphine (T-M) or lidocaine plus morphine (T-LM) at the same doses. Postoperative analgesia was assessed for 24 hours using a Visual Analog Scale (VAS) and the Glasgow Composite Pain Scale (GCPS). Rescue analgesia was performed if the evaluation score exceeded 50% of the VAS and/or 33% of the GCPS. The pain score and postoperative opioid requirements did not differ among the treatments. Rescue analgesia was administered to 1/8 dogs in the T-M and T-LM, and to 3/8 dogs in the T-L. Lidocaine, morphine or lidocaine/morphine CRI may be efficacious techniques for pain management in the first 24 hours post-surgery. However, the two drugs administered together did not reduce the postoperative opioid requirement in dogs undergoing fracture repair. Key words: Anesthesia. Analgesics. Analgesics, Opioid. Lidocaine. Morphine. Dogs.

Extradural anesthesia with lidocaine combined with fentanyl or methadone to ovariohisterectomy in dogs.

PURPOSE: To compare the cardiopulmonary effects and the quality of anesthesia of the extradural lidocaine in combination with fentanyl or morphine in bitches undergoing ovariohysterectomy. METHODS: Sixteen female dogs, were sedated with intramuscular acepromazine (0.05 mg kg-1), followed by anesthetic induction with intravenous propofol (4 mg kg-1), to perform the lumbosacral puncture. The animals were randomly assigned to two treatments: T-F (n=8) extradural administration of fentanyl (5 µg kg-1), T-M (n=8) extradural administration of methadone (0.3mg kg-1). In both treatment groups, opioids were combined with lidocaine, in order to make up a final volume of 0.4 mL kg-1. Heart rate (HR), respiratory rate (RR), systolic arterial blood pressure (SABP), intra-operative anesthetic supplementation, blood gases and adverse effects were investigated. RESULTS: HR, arterial pH and blood gases did not differ between treatments at any time point. RR and SABP decreased after epidural anesthesia, but the values were in terms of the physiological range of dogs. Intra-operative anesthetic supplementation was required in 50% and 62.5% of the fentanyl and methadone treated dogs, respectively. CONCLUSION: The extradural lidocaine in combination with fentanyl or morphine allowed cardiopulmonary stability, however sufficient sensitive blockade was not provided in 100% of the dogs.

Extradural anesthesia with lidocaine combined with fentanyl or methadone to ovariohisterectomy in dogs

PURPOSE: To compare the cardiopulmonary effects and the quality of anesthesia of the extradural lidocaine in combination with fentanyl or morphine in bitches undergoing ovariohysterectomy. METHODS: Sixteen female dogs, were sedated with intramuscular acepromazine (0.05mg kg-1), followed by anesthetic induction with intravenous propofol (4mg kg-1), to perform the lumbosacral puncture. The animals were randomly assigned to two treatments: T-F (n=8) extradural administration of fentanyl (5µg kg-1), T-M (n=8) extradural administration of methadone (0.3mg kg-1). In both treatment groups, opioids were combined with lidocaine, in order to make up a final volume of 0.4mL kg-1. Heart rate (HR), respiratory rate (RR), systolic arterial blood pressure (SABP), intra-operative anesthetic supplementation, blood gases and adverse effects were investigated. RESULTS: HR, arterial pH and blood gases did not differ between treatments at any time point. RR and SABP decreased after epidural anesthesia, but the values were in terms of the physiological range of dogs. Intra-operative anesthetic supplementation was required in 50% and 62.5% of the fentanyl and methadone treated dogs, respectively. CONCLUSION: The extradural lidocaine in combination with fentanyl or morphine allowed cardiopulmonary stability, however sufficient sensitive blockade was not provided in 100% of the dogs.

Infusão contínua intravenosa de midazolam isolado ou associado ao fentanil para realização de endoscopia em suínos / Continuous infusion rate of midazolam alone or in combination with fentanyl for endoscopy in swine

Com este estudo objetivou-se avaliar o efeito cardiorrespiratório e a qualidade da anestesia e da recuperação pós-anestésica decorrentes da associação cetamina e xilazina seguida da infusão contínua intravenosa (IV) de midazolam isolado ou associado ao fentanil, em suínos. Foram avaliadas 10 porcas adultas, da raça Landrace, com peso médio de 170±4kg, submetidas à endoscopia. Todos os animais foram medicados pela via intramuscular com cetamina (4mg kg-1) associada à xilazina (2mg kg-1). Vinte minutos após, foi realizado um bolus IV de cetamina (2mg kg-1), seguida da infusão contínua IV de midazolam (0,5mg kg-1h-1 GM, n=5), ou midazolam (0,25mg kg-1h-1) associado ao fentanil (4µg kg-1 h-1 GMF, n=5). Foram avaliados: frequência cardíaca (FC) e ritmo cardíaco, pressão arterial sistólica (PAS), temperatura retal (T), frequência respiratória (f), variáveis hemogasométricas (PaO2, PaCO2, pH, HCO3-, SaO2), qualidade da anestesia e qualidade e tempo da recuperação anestésica (RA). A análise estatística foi realizada por meio de análise de variância, teste de Tukey e o teste não paramétrico de Mann-Whitney (P<0,05). A qualidade da anestesia foi semelhante entre os tratamentos, sendo possível a realização da endoscopia em ambos os grupos. Os parâmetros cardiorrespiratórios, bem como os gases sanguíneos, o pH, o bicarbonato e a saturação da oxihemoglobina não variaram entre os diferentes tratamentos. O tempo de recuperação anestésica foi de 98±15 e 79±17 minutos no GM e GMF, respectivamente, sem diferença entre os grupos. A qualidade da RA não diferiu significativamente entre os grupos. Conclui-se que ambos os tratamentos determinaram estabilidade cardiorrespiratória e foram satisfatórios para a realização de endoscopia em suínos. No entanto, apesar da ausência de diferença estatística, menor tempo de RA foi observado nos animais tratados com a infusão contínua de midazolam associado ao fentanil.

The aim of this study was to evaluate the cardiopulmonary effects, the quality of anesthesia and the post-anesthetic recovery of ketamine and xylazine premedication following intravenous (IV) continuous rate infusion of midazolam alone or in combination with fentanyl, in swine. Ten Landrace adult pigs that underwent endoscopy were evaluated. All pigs were premedicated with ketamine (4mg kg-1) and xylazine (2mg kg-1) by intramuscular administration. After twenty minutes, intravenous ketamine (2mg kg-1) was injected, following IV continuous rate infusion of midazolam (0.5mg kg-1 h-1 GM, n=5) or midazolam (0.25mg kg-1 h-1) plus fentanyl (4µg kg-1 h¹ GMF, n=5). Heart and respiratory rates, systolic arterial blood pressure, rectal temperature, arterial blood gases, quality of anesthesia and recovery, and time for recovery were investigated. Statistical analysis was performed with One-Way ANOVA, Tukey test and Mann-Whitney test (P<0.05). The quality of anesthesia was similar between treatments, and endoscopy was able to be performed in both groups. Cardiopulmonary variables and blood gases did not differ between groups. The recovery time was 98±15 and 79±17 minutes in GM and GMF, respectively, without significant difference between treatments. The quality of recovery did not differ between groups. The results allowed us to conclude that both treatments provide cardiopulmonary stability and were satisfactory to swine endoscopy. However, despite of absence of significant difference, shorter time of recovery was observed with midazolam/fentanyl infusion.