Magnesium Sulfate Improves Postoperative Analgesia in Laparoscopic Gynecologic Surgeries
Condition: Pain, Postoperative
MeSH terms: Pain, Postoperative
Study type: Interventional
Phase: Phase 4

Summary: 
      Magnesium sulfate has been reported to improve postoperative pain, but evidence is still
      controversial. Some studies demonstrated benefits while others concluded that there is no
      efficacy. Aim: the aim of the study was to compare the effect of intravenous infusion of
      magnesium sulfate to ketorolac during laparoscopic gynecologic oncology surgeries. Methods:
      We designed a double-blind randomized controlled trial that compared intravenous magnesium
      sulfate to ketorolac and saline solution in postoperative pain, morphine consumption and
      opioid related side effects.
    

Detailed description: 
      Sixty American Society of Anesthesiologists (ASA) I-II patients undergoing laparoscopic
      gynecologic oncology surgeries are enrolled in this study.

      Patients were randomized to receive either intravenous ketorolac 30 mg in bolus followed by
      saline infusion (Group K), intravenous magnesium sulfate 20 mg/kg in bolus followed by
      magnesium 2 mg/kg/h (Group M) or intravenous saline solution 20 ml in bolus followed by
      saline infusion during the entire procedure (Group S). The study use a double-blinded
      methodology with random allocation into three groups using sealed opaque envelopes numbered 1
      to 60, containing the instructions for the study. An independent anesthesiologist not
      involved in the study prepared the solutions and an observer who was also blinded to the
      patient's group records the data.

      In the preoperative visit, patients that agree to participate are instructed about numeric
      rating scale (NRS) and the Patient Controlled Analgesia (PCA) device.

      The night before surgery, patients are premedicated with midazolam 7.5 mg per os. Upon
      arrival in the operating room, monitoring devices (ECG, non-invasive arterial pressure,
      capnography, pulse oximetry) and a bispectral index (BIS) monitor are established. An
      intravenous line is secured, general intravenous anesthesia is induced with target infusion
      remifentanil and propofol. Cisatracurium besylate (0.5 mg/kg) is given to facilitate tracheal
      intubation and controlled ventilation is adjusted to maintain normocapnia with a 50% oxygen
      fraction administered. Then, the study medications are administered in bolus during 20
      minutes, followed by continuous infusion of the specific solution, according to the study
      group to which the patient belonged, as described before.

      At the end of the surgery, the study drugs are discontinued before the patient is extubated.
      If patients present clinical signs of residual neuromuscular blockade, they receive atropine
      0.01mg/kg and neostigmine 0.04mg/kg. All patients receive dipyrone 30 mg/kg in bolus and a
      PCA device is connected to the intravenous line before discharge to the Post Anesthesia Care
      Unit (PACU). PCA solution containing morphine 1mg/ml in 0.9% saline, is set to give bolus of
      2ml (2mg) with a 10min lockout interval.

      In the postoperative period, the anesthesiologist responsible for the study question the
      intensity of pain in the patients using two methods: numerical rating scale (NRS) (0=no pain
      and 10=worst pain imaginable) and descriptive verbal scale (no pain, mild pain, moderate pain
      or severe pain - at emergence from anesthesia and after 20, 30 and 60 minutes, while in PACU.
      Patients are instructed to use the PCA device whenever they feel pain. Agitation and Sedation
      are monitored using RASS scale and patient is considered sedated if RASS ≤ -1. Episodes of
      nausea, vomiting, respiratory depression or pruritus are also recorded.

      Patients are discharged to the ward after 60 minutes, if minimum criteria for discharge are
      met.

      Time (in minutes) to the first morphine rescue, and total consumption of morphine in PACU are
      registered. After 24 hours, pain intensity score, total morphine consumption and side effects
      are also recorded and PCA device is disconnected.
    

Intervention name(s): Ketorolac; Magnesium; Saline solution
Intervention type(s): Drug; Drug; Drug
Intervention description(s): Patients received intravenous injection of ketorolac (30 mg) in bolus; then, saline solution was continuously infused during the entire procedure (Group K),; Patients received intravenous magnesium sulfate (20 mg/kg) in bolus, then magnesium sulfate (2 mg/kg/h) was continuously injected during the procedure (Group M); intravenous saline solution (20 ml) was injected in bolus, followed by continuous infusion of saline solution during the entire procedure (Group S).
Other intervention name(s): Toradol; Magnesium sulfate; Sodium chloride
Intervention MeSH terms: Ketorolac; Magnesium Sulfate
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Treatment
Keywords: pain, postoperative; anesthesia adjuvants; magnesium sulfate