Effectiveness of intravenous magnesium sulfate to attenuate hemodynamic changes in laparoscopic surgery: a systematic review and meta-analysis
Authors: Greenwood Jennifer , Nygard Brian , Brickey Doug 
Published: October 2020

ABSTRACT

Objective:
The purpose of this systematic review and meta-analysis was to determine the effectiveness of intravenous magnesium sulfate when used to attenuate hemodynamic fluctuations associated with the creation of pneumoperitoneum in adults undergoing laparoscopic surgery.

Introduction:
Laparoscopic surgery has gained popularity as a result of improved patient outcomes postoperatively, but pneumoperitoneum alters the patient's physiology and hemodynamic profile during the intraoperative period. Magnesium sulfate is a nonopioid agent known for its ability to blunt the physiologic sympathetic response associated with exposure to noxious stimuli. Magnesium sulfate may be efficacious in promoting anesthetic management that optimizes a patient's cardiopulmonary function while minimzing opioid use.

Inclusion criteria:
Studies with participants at least 18 years old undergoing any elective laparoscopic surgery using pneumoperitoneum with CO2 insufflation were included. Studies were excluded if patients were being treated for pheochromocytoma. Studies eligible for inclusion employed any intravenous dosing strategy of magnesium sulfate, administered at any point in the perioperative period for the purpose of blunting the sympathetic response to creation of a pneumoperitoneum. The comparator utilized was normal saline.

Methods:
A systematic search of MEDLINE, CINAHL, Cochrane Library, Google Scholar, Trip Database, MedNar, Grey Literature Report, ClinicalTrials.gov, and ProQuest Dissertations and Theses was conducted to identify both published and unpublished studies. The search was limited to studies written in the English language and performed on human subjects. Studies were selected for review based on inclusion criteria and were appraised by two reviewers using the appropriate JBI standardized appraisal tool. Data extraction was performed for all outcome variables. Data were pooled using the JBI System for the Unified Management, Assessment and Review of Information. Mean differences (95% confidence interval) were calculated for all continuous variables. Meta-analysis using a fixed effects model was performed at various time points for heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure. Standard GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) evidence assessment was also reported.

Results:
A total of six randomized controlled trials were included in the review. Meta-analysis of data for biophysical parameters (heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure) at five minutes, 10 to 15 minutes, 30 minutes after pneumoperitoneum, and at the end of surgery showed a consistent reduction in the magnesium groups compared to placebo. Support for all outcome variables was determined to be high using the GRADE criteria.

Conclusion:
The administration of magnesium sulfate consistently demonstrated improved hemodynamic measurements during laparoscopic surgery. All doses administered in the included studies proved beneficial compared to placebo. Magnesium sulfate should be considered as an adjunct agent in laparoscopic surgery to blunt the sympathetic nervous system response to surgical stimulation. The quality of the included studies was high, but small sample sizes and selection of healthy participants may limit the generalizability of the results. The use of magnesium sulfate may have improved effects on patients with significant health comorbidities, but the limitations of the included studies related to sample demographics make the evidence inconclusive.

Systematic: review registration number:
PROSPERO (CRD42019139991)