Ketamine Versus Magnesium Sulfate in the Time and Awakening Quality of General Anesthesia.

  • participants needed
  • sponsor
    University of Sao Paulo General Hospital
Updated on 31 January 2023


The introduction of the laparoscopic technique for cholecystectomy significantly reduced the incidence and intensity of postoperative pain, with improvement in other markers, such as patient satisfaction, and reduction in hospital stay. However, pain in the postoperative period of laparoscopic cholecystectomy is still a concern that challenges modern anesthesiology. Ketamine and magnesium sulfate are two blockers of N-methyl-D-aspartate (NMDA) receptors with the ability to reduce postoperative pain and postoperative opioid consumption. A frequent concern among anesthesiologists is the quality and time of awakening in patients receiving these medications The main objective of this trial is to compare the quality and time of awakening in patients receiving magnesium sulfate or ketamine.

The secondary objective is to compare postoperative analgesia during the postoperative hospital stay.

Hypothesis: Our hypothesis is that patients have a faster awakening when they receive magnesium sulfate as an analgesic adjunct, when compared to patients who receive ketamine .

Design: this is a prospective, controlled, covered and randomly distributed trial.


Intervention: the sample of participants will be distributed in 4 groups. The placebo (PG) group will receive 100 ml of saline solution 15 min before anesthetic induction. The ketamine group (KG) will receive 0.3 mg / kg of ketamine in saline (total volume of 100 ml) 15 min before anesthetic induction. The magnesium sulfate group (SG) will receive 40 mg / kg of magnesium sulfate in saline solution (total volume of 100 ml) 15 min before anesthetic induction. The mixed group (MG) will receive 0.15 mg / kg of ketamine + 20 mg / kg of magnesium sulfate in saline solution (total volume of 100 ml) 15 min before anesthetic induction. All participants will be submitted to balanced anesthesia. Anesthetic induction will be started after 5 min of pre-oxygenation, with lidocaine 1.5 mg / kg, fentanyl 3 µg / kg, propofol until clinical hypnosis, cisatracurium 0.1 mg / kg and intubation after adequate neuromuscular relaxation. Maintenance will be with sevoflurane in concentration under clinical demand, repeating boluses of fentanyl 1 µg / kg and cisatracurium 0.03 mg / kg, as needed.

Primary Outcomes: time between the end of anesthetic administration and bispectral index (BIS) > 60, and a battery of neuropsychological tests to assess postoperative cognitive dysfunction tested in the Brazilian population 3 h after the end of anesthetic administration.

Secondary Outcomes: response to the brief pain inventory questionnaire and opioid consumption in the first 2 postoperative days.

Recruitment and timeline : patients will be recruited in the pre-anesthetic evaluation and assessments will be made of covertly in the immediate postoperative period and during the two days after surgery, being registered the pain scores and the consumption of opioids.

Sample calculation: the sample of 120 participants was calculated with a 95% confidence index and 80% statistical power. To compensate for losses, 140 individuals will be recruited.

Condition Awakening, Post-Anesthesia Delayed
Treatment General anesthesia, Ketamine plus general anesthesia, Magnesium sulfate plus general anesthesia, ketamine plus magnesium sulfate plus general anesthesia
Clinical Study IdentifierNCT04360473
SponsorUniversity of Sao Paulo General Hospital
Last Modified on31 January 2023

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