Methadone for Postoperative Pain
Condition: Pain, Postoperative
MeSH terms: Pain, Postoperative
Study type: Interventional

Summary: 
      The aim of this study is to compare the efficacy of methadone versus morphine in dealing with
      postoperative pain, in laparoscopic cholecystectomy under total intravenous anesthesia
      (TIVA); Efficacy is defined in terms of the difference of milligrams in morphine used as
      rescue analgesia postoperatively. Our hypothesis is that methadone is more effective than
      morphine for postoperative pain treatment.
    

Detailed description: 
      Patients undergo laparoscopic cholecystectomy at Almirante Nef Naval Hospital will be
      recruited, between March and July 2013. The sample size was calculated to obtain an average
      difference of 4 mg of morphine (DE 1.5) to 3 mg of morphine (DE 1.5), with a power of 80% and
      a significance level of 0.05. This came down to 36 randomized patients into each group, so 86
      patients will be recruited considering a 15% loss to follow up.

      Before signing an informed consent, we will explain to them how to classify pain intensity
      numerical rating scale (NRS) and this will be evaluated periodically during the first 24
      hours after surgery.

      General anesthesia will be based on Remifentanil and Propofol, titrated to achieve bispectral
      index (BIS) between 40 and 60. Patients will be randomized into methadone group (ME) and
      morphine group (MO), they will receive 0.08 mg / kg bolus of methadone or 0.08 mg / kg bolus
      of morphine as applicable at the time of beginning surgery. Postoperative analgesia will be
      standard for both groups. Patient´s demographic data will be filed as well as surgical
      timings.

      All patients will remain in the anesthetic recovery room for the first two hours , to get a
      record taken of vital signs and measurement of NRS at 5, 15, 30, 60 and 120 minutes. If NRS
      is greater than or equal to 4, 1 mg of morphine ev will be used as analgesic rescue. In room
      measuring NRS continue hospitalized at 4, 8, 12 and 24 hours postoperatively and were used as
      rescue analgesia if ketorolac 30mg ev NRS is greater than or equal to 4. The amount of
      morphine is registered and ketorolac rescue of both groups as well as pain assessment scores.
      The occurrence of adverse effects such as nausea, vomiting, pruritus, urinary retention and
      respiratory depression is also recorded in both groups, to be compared later as a secondary
      objective.
    

Intervention name(s): Morphine; Methadone; TIVA
Intervention type(s): Drug; Drug; Drug
Intervention description(s): Morphine group,receive morphine 0.08 mg / kg at the start of surgery; Methadone group,receive methadone 0.08 mg / kg at the start of surgery; TIVA: General anesthesia will be based on Remifentanil and Propofol (TIVA-TCI), titrated to achieve bispectral index (BIS) between 40 and 60.
Intervention MeSH terms: Morphine; Methadone
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Care Provider)
Primary purpose: Treatment
Keywords: Pain, Postoperative; Analgesics, Opioid; Methadone; Morphine