Analgesia em procedimentos cirúrgicos de abdômen superior com bloqueio interpleural / Analgesia in upper abdominal surgery with interpleural block

JUSTIFICATIVA E OBJETIVOS: Pesquisas empregando bloqueio interpleural com anestésico local, opioide e agonista Alfa2-adrenérgico ou bloqueador do receptor N-metil-D-aspartato (NMDA), observaram a ocorrência de analgesia pós-operatória em cirurgias de abdômen superior. O objetivo deste estudo foi observar a presença de dor no pós-operatório de cirurgias de colecistectomia por via subcostal.MÉTODO: Após aprovação pelo Comitê de Ética, participaram do experimento aleatório e prospectivo, 40 pacientes, de ambos os sexos, com idade variando de 18 a 50 anos, peso entre 50 e 100 kg, estado físico ASA I e II, submetidos à colecistectomia por via subcostal, sob anestesia geral associada ao bloqueio interpleural. Foram administradas levobupivacaína a 0,5% (100 mg) com adrenalina 1:200.000 (5 µg.mL-1) ou ropivacaína a 0,75% (150 mg), morfina (3 mg) e clonidina (3 µg.kg-1) ou cetamina (0,5 mg.kg-1), ao nível EIC7, na linha axilar média, com agulha de Tuohy 17G, por via interpleural. A indução da anestesia geral foi realizada com a injeção de etomidato (0,2 mg.kg-1), alfentanil (30 µg.kg-1) e rocurônio (0,6 mg.kg-1) e a manutenção com oxigênio e isoflurano (0,5 vol% a 3,0 vol%). A analgesia pós-operatória, analisada pela escala analógica visual (EAV), foi observada às 6h, 12h, 18h e 24h após o término do ato operatório.RESULTADOS: Apresentaram dor pós-operatória: grupo RMC (ropivacaína, morfina e clonidina), um até 6h, seis entre 6 e 12h e um entre 18 e 24h; grupo RMK (ropivacaína, morfina e cetamina), quatro até 6h, quatro entre 6 e 12h, um entre 12 e 18h e um entre 18 e 24h; grupo LMC (levobupivacaína, morfina e clonidina), quatro até 6h e quatro entre 6 e 12h; grupo LMK (levobupivacaína, morfina e cetamina, cinco até 6h, quatro entre 6 e 12h e um entre 12 e 18h. Aplicando o teste Exato de Fisher observou-se diferença estatística significante entre o tempo de observação até 6h e os demais no grupo RMC; entre o tempo de observação até 6h e os 12-18h e 18-24h nos grupos RMK e LMK. Não ocorreram complicações relacionadas ao bloqueio interpleural.CONCLUSÃO: A necessidade de associar opioide ao analgésico comum para abolir a dor, em cirurgias de colecistectomia por via subcostal, ocorreu em número reduzido de pacientes.

BACKGROUND AND OBJECTIVES: Researches using interpleural block with local anesthetics, opioid and alpha2-adrenergic agonist or N-Methyl-D-aspartate (NMDA) receptor blocker have shown the presence of postoperative analgesia in upper abdominal surgeries. This study aimed at observing the presence of pain in the postoperative period of subcostal cholecystectomies. METHOD: After The Ethics Committee approval, participated in this randomized, prospective study 40 patients of both genders, aged 18 to 50 years, weighing between 50 and 100 kg, physical status ASA I and II, submitted to subcostal cholecystectomy under general anesthesia associated to interpleural block. The following drugs were administered: 0.5% levobupivacaine (100 mg) with 1:200.000 epinephrine (5 µg.mL-1) or 0.75% ropivacaine (150 mg), morphine (3 mg) and clonidine (3 µg.kg-1) or ketamine (0,5 mg.kg-1), at EIC7, in the medium axillary line with 17G Tuohy needle by interpleural route. General anesthesia was induced with etomidate (0.2 mg.kg-1), alfentanil (30 µg.kg-1) and rocuronium (0.6 mg.kg-1) and was maintained with oxygen and isoflurane (0.5 vol% at 3.0 vol%). Postoperative analgesia, evaluated by the visual analog scale (VAS), was observed at 6h, 12h, 18h and 24h after surgery completion.RESULTS: Postoperative pain was observed: one patient up to 6h, six between 6 and 12h and one between 18 and 24h in the RMC group (ropivacaine, morphine and clonidine); four patients up to 6h, four between 6 and 12h, one between 12 and 18h and one between 18 and 24h in the RMK group (ropivacaine, morphine and ketamine); four patients up to 6h, and four between 6 and 12h in the LMC group (levobupivacaine, morphine and clonidine); five patients up to 6h, four between 6 and 12h, and one between 12 and 18h in the LMK group (levobupivacaine, morphine and ketamine). Fisher's Exact test has shown statistically significant difference between 6h observation time and the others in the RMC group; between 6h observation time and 12-18h and 18-24h in RMK and LMK groups. There were no interpleural block-related complications.CONCLUSION: Only a small number of patients needed the association of opioid to normal analgesics to abolish pain in subcostal cholecystectomy surgeries.

The Mechanism of Action of Intrathecal Morphine in Neuropathic Pain Induced by Nerve Ligation: The Effect of Naloxone / 대한마취과학회지

BACKGROUND: Although the efficacy of morphine in the neuropathic pain state is somewhat controversial, spinally administered morphine reversed the tactile allodynia in our previous animal study. Using a von Frey filament test, we examined the mechanism of action of intrathecal morphine by administration of the opioid receptor antagonist naloxone in a rat model of neuropathic pain induced by nerve ligation injury. METHODS: Male Sprague Dawley rats were prepared with tight ligation of the left lumbar 5th and 6th spinal nerves and a chronic lumbar intrathecal catheter. Intrathecal doses (0.3 and 1 microgram) of morphine were administered to attenuate the allodynic state. Naloxone was administered intrathecally (10 microgram) or intraperitoneally (30 and 150 microgram) in order to investigate the reversal of the antiallodynic effect of morphine. Allodynic thresholds for left hindpaw withdrawal to the von Frey hairs test were assessed and converted to %MPE. RESULTS: A reduced effect of tactile allodynia by intrathecal morphine was produced. Naloxone 10 microgram (IT) and 150 microgram (IP), but not naloxone 30 microgram (IP), reversed the antiallodynic effect of intrathecal morphine (P < 0.05). CONCLUSIONS: The results suggest that the mechanism of tactile antiallodynia induced by intrathecal morphine may include the opioid receptor system at the spinal and supraspinal level in a rat model of nerve ligation injury.

Interaction between Neostigmine and Morphine in the Neuropathic Pain Model / 대한마취과학회지

BACKGROUND: Spinally administered neostigmine, but not morphine, has been well known to reverse the mechanical allodynia in human and animal studies. The efficacy of morphine in neuropathic pain state is somewhat controversial. Using an isobolographic analysis, we examine the spinal interaction between neostigmine and morphine in a rat model of neuropathic pain. METHODS: Male Sprague Dawley rats were prepared with tight ligation of left lumbar 5th and 6th spinal nerves and chronic lumbar intrathecal catheter. Intrathecal dose response curves were established for the antiallodynic effect of neostigmine (0.3, 1.0, 3.0, and 10 microgram) and morphine (0.3, 1.0, 3.0, and 10 microgram) alone to obtain the ED50 for each agent. ED50 fractions (1/2, 1/4, 1/8, and 1/16) of drug combination of neostigmine-morphine were administered. Allodynic thresholds for left hindpaw withdrawal to von Frey hairs application were assessed and converted to %MPE. The ED50 of neostigmine-morphine combinations was established and isobolographic analysis of the drug interaction was carried out. RESULTS: Intrathecal neostigmine and morphine alone produced dose-dependent reductions of tactile allodynia. ED50 values are 0.43 microgram (0.21~0.86 microgram) for neostigmine and 0.39 microgram (0.07~2.01 microgram) for morphine. The log dose responses were plotted from the peak effect of %MPE in each group of neostigmine and morphine. The experimental ED50 1.34E-2 microgram (2.1E-4-0.85 microgram) for neostigmine and morphine combination was found to be significantly below the theoretical additive ED50 value 0.41 microgram (P<0.05). CONCLUSION: The results suggest that intrathecal neostigmine and morphine alone produce a dose dependent antagonism on touch evoked allodynia and intrathecal neostigmine is synergistic at the spinal level when combined with intrathecal morphine in a rat model of neuropathy.

Analgesic Effects of Intraperitoneal Morphine, Nalbuphine, and Ketorolac on the Formalin Test in Rats / 대한마취과학회지

BACKGROUND: The antinociceptive effect and the potency of systemically administered morphine (micro-agonist), nalbuphine (agonist-antagonist), and ketorolac (cyclooxygenase inhibitor) was examined in rats using the formalin test. METHODS: Male Sprague-Dawley rats (250~300 g) received intraperitoneal injection of either saline or 3 doses of each test drug (0.3, 1.0, 3.0 mg/kg of morphine, 0.3, 1.0, 3.0 mg/kg of nalbuphine, and 10, 30, 100 mg/kg of ketorolac) 30 minutes prior to formalin injection. 50 microliter of 10% formalin was injected into the dorsal surface of the right hindpaw after 1 minute of 4% halothane induction. The construction of the dose-response curves and the determination of doses producing 50% maximum possible effect (ED50) were computed. RESULTS: Intraperitoneal injection of morphine, nalbuphine and ketorolac resulted in the significant, dose-dependent supression of both phases, but nalbuphine has a ceiling effect at high dose for analgesia at the phase I of the formalin test. The rank order of relative potency in rats to the formalin test was nalbuphine (1.16)>morphine (1)>>ketorolac (0.1) in phase I, morphine (1)>nalbuphine (0.61)>>ketorolac (0.02) in phase IIa, and morphine (1)>nalbuphine (0.57)>>ketorolac (0.03) in phase IIb. CONCLUSION: Comparing the systemic analgesic potency, nalbuphine and ketorolac will be needed in dosages 1.5 and 50 times that of morphine, respectively. These results suggest that ketorolac is not good enough as a single analgesic drug in preemptive analgesia for major surgery.

Intra-articular Morphine, Bupivacaine-Morphine for Pain Relief after Arthroscopy Surgery of the Knee Joint / 대한마취과학회지

BACKGROUND: Evidence has accumulated that opioids can produce potent antinociceptive effects by interacting with opioid receptors in peripheral tissues. Bupivacaine is potent analgesic with early peak onset in the postoperative period. The combination of intra-articular bupivacaine and morphine has been suggested as an ideal analgesic after knee arthroscopy. METHODS: Thirty patients scheduled for knee arthroscopy under general anesthesia were allocated randomly to two groups. Group 1 received morphine 5 mg in normal saline 25 ml, group 2 received morphine 5 mg in 0.25% bupivacaine 25 ml intraarticularly, and all solutions contained 1:200,000 epinephrine. Tourniquet was inflated above knee joint for 10 minutes after injection in each of the patients. Postoperative pain was assessed using the visual analogue scale at 1, 2, 3, 4, 6, 12 and 24 hours after the intra-articular injection. The need for supplemental analgesic was recorded. RESULTS: Patients in the group 2 had lower pain scores than group 1 at first and second hour. There were no significant differences from 3 hours to 24 hours postoperative period. Supplemental analgesic requirements were significantly greater in group 1 than group 2 for the first 3 hours. CONCLUSIONS: It is concluded that, after knee arthroscopy, intra-articular morphine 5 mg in 0.25% bupivacaine 25 ml results in satisfactory analgesia with small amount of supplementary analgesic.