ObjectivesSurgical patients still commonly experience postoperative pain. With the increasing prevalence of obesity, there is a growing demand for surgical procedures by this population. Intraoperative use of methadone has not been well assessed in this population.Materials and methodsPatients with a body mass index of 35 kg/m2 or more undergoing bariatric surgery were randomly assigned to receive either fentanyl (group F) or methadone (group M) in anesthesia induction and maintenance. The primary outcome was morphine consumption during the first 24 hours after surgery through a patient-controlled analgesia device. Secondary outcomes were pain scores at rest and while coughing, opioid related side effects, and patient satisfaction. The patients were also evaluated 3 months after surgery for the presence of pain, dysesthesia, or paresthesia at surgical site.ResultsPostoperative morphine consumption was significantly higher for patients receiving fentanyl than methadone during the postoperative period at 2 hours (mean difference [MD] 6.4 mg; 95% CI 3.1–9.6; P<0.001), 2–6 hours (MD 11.4 mg; 95% CI 6.5–16.2; P<0.001), 6–24 hours (MD 10.4 mg; 95% CI 5.0–15.7; P<0.001), and 24–48 hours (MD 14.5 mg; 95% CI 3.9–25.1; P=0.01). Patients from group F had higher pain scores until 24 hours postoperatively, higher incidence of nausea and vomiting, lower satisfaction, and more evoked pain at surgical scar at the 3-month postoperative evaluation than group M.ConclusionIntraoperative methadone can safely lower postoperative opioid consumption and improve postoperative pain scores compared with fentanyl in morbidly obese patients.

Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K+ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K+ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220 g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E2- (PGE2, 400 ng/paw; 50 µL; intraplantar injection) and carrageenan-induced hypernociception (500 µg/paw; 100 µL; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE2) by a selective inhibitor of nitric oxide synthase (L-NAME; 90 mg/kg, ip) and L-arginine (200 mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE2) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE2; 8 µg/paw) and the ATP-sensitive K+ channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE2; 160 µg/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels.

TNBS-induced colitis causes antinociception in the rat paw. This disorder appears to be mediated by activation of the NO/cGMP/PKG/KATP pathway, endocannabinoids and endogenous opioids. This information may contribute to a better understanding of peripheral neurological dysfunctions occurring in Crohn's disease.

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A cirurgia de hérnia inguinal (HI) é um dos procedimentos mais comuns na prática do cirurgião geral. Estima-se que 20 milhões dessas operações sejam realizadas no mundo anualmente. Com o advento da técnica sem tensão e implante de tela sintética, as taxas de recidiva caíram expressivamente e a recidiva deixou de ser a principal complicação tardia após o reparo da hérnia inguinal. Hoje a principal complicação pós-operatória tardia da cirurgia de HI é a dor crônica inguinal pós-operatória (DCIP). A definição de DCIP é a dor pós-operatória da região inguinal após 3-6 meses da cirurgia. Relatamos o caso de um jovem paciente do sexo masculino que se apresentou com DCIP após ter sido previamente submetido a duas herniorrafias inguinais. Inicialmente apresentava dor inguinal a esquerda sem abaulamento evidente e na ocasião foi submetido a herniorrafia inguinal esquerda pela técnica de Lichtenstein. Não houve resolução da dor após a cirurgia. Após 1 ano foi novamente operado, dessa vez bilateralmente e infelizmente evoluiu com piora da dor apresentava dor predominantemente neuropática (em queimação e com irradiação para região testicular bilateralmente) e intensidade moderada (escala visual analógica 6), sem melhora com anti-inflamatórios não esteroidais ou analgésicos. Apresentava dor ao toque do anel inguinal externo bilateralmente, hiperestesia no teritório de nervos genito-femoral, ílio-hipogástrico e ílio-inguinal do lado esquerdo e hipoestesia no território dos três nervos do lado direito. Apresentou alívio temporário da dor após bloqueio anestésico inguinal bilateral. Paciente foi então submetido a triplo-neurectomia bilateral com remoção das telas de polipropileno. Em seguimento um ano após o tratamento cirúrgico, o paciente permanece sem dor inguinal.