Does Intraoperative Methadone Prevent Postoperative Pain in Bariatric Surgery?
Condition: Pain, Postoperative; Chronic Pain
MeSH terms: Chronic Pain; Pain, Postoperative
Study type: Interventional
Phase: Phase 4

Summary: 
      The recent increase in obesity has led to an increase in the need for bariatric surgery. In
      this group of patients the postoperative pain management is of vital importance. One strategy
      to improve postoperative analgesia is the use of intraoperative methadone, specially in those
      patients which regional anesthesia is not feasible. There is evidence that the use of
      intraoperative methadone can lead to a analgesia lasting 24 to 36 hours, while not associated
      with increased side effects when compared to other opioids with short or intermediate
      duration of action. In this study the investigators will evaluate the efficacy of
      intraoperative methadone in reducing postoperative pain and opioid consumption.
    

Detailed description: 
      Despite recent developments in postoperative pain control, many patients still suffer from
      moderate to severe pain after surgery. It is estimated that postoperative severe pain occurs
      in 20 to 40% of surgical procedures. With the recent increase in obesity incidence in the
      last years, the need for bariatric surgical intervention is greater. The management of
      postoperative pain in obese patients is particularly important, since this population have
      increased susceptibility to cardiovascular, pulmonary and thromboembolic perioperatively.

      One of the strategies to improve pain management in the perioperative period is the
      intraoperative use of intravenous methadone, given its pharmacokinetic profile, specially in
      those patients in which regional anesthesia is contraindicated. Methadone is an opioid μ
      (MOR) receptor agonist, also a glutamate antagonist by blocking the N-methyl-D-aspartate
      (NMDA) receptor and a reuptake of serotonin and noradrenaline inhibitor. Intraoperative
      analgesia generated by administration of 20 to 30 mg methadone can last 24 to 36 hours. There
      is also evidence that methadone at 0.2 to 0.3 mg / kg is not associated with an increased
      incidence of side effects compared to other opioids with short or intermediate duration of
      action, such as fentanyl, sufentanyl and morphine.

      The aim of this study is to evaluate the efficacy of intraoperative methadone in reducing
      postoperative pain and opioid consumption in patients undergoing open gastroplasty with or
      without associated Roux Y. Patients will undergo standardized general anesthesia, and the
      opioid used in anesthesia induction is methadone 0.15 mg / kg fentanyl or 6 mcg / kg bolus
      with additional if necessary. After extubation a intravenous morphine patient controlled
      analgesia device will be already available in the operating room. Groups will be compared
      regarding opioid consumption, pain scores, side effects, patient satisfaction and development
      of chronic postoperative pain.
    

Intervention name(s): Use of Intraoperative Intravenous Methadone; Use of Intraoperative Intravenous Fentanyl
Intervention type(s): Drug; Drug
Intervention description(s): The intervention group will be given intravenous methadone at a fixed induction dose (0,15 mg / kg) and intraoperative boluses as judged necessary by the anesthesiologist; The active control group will be given intravenous fentanyl at a fixed induction dose (6 mg / kg) and intraoperative boluses as judged necessary by the anesthesiologist
Other intervention name(s): Methadone; Methadone
Intervention MeSH terms: Fentanyl; Methadone
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Methadone; Pain, Postoperative; Chronic Pain; Bariatric Surgery