Comparison of Two Magnesium Sulfate Protocols in Opioid-Free Anesthesia for Bariatric Surgery

NCT07077031 | Completed

• 1 other identifier: 25.04.2520-GHM
• Study Type: observational
• Target: 110
• Locations: 1 country
• Sites: 1

Brief Summary

This retrospective observational study aims to compare postoperative morphine consumption in patients undergoing bariatric surgery with opioid-free anesthesia (OFA) using two different intravenous magnesium sulfate administration protocols: a single bolus versus a bolus followed by continuous infusion. Medical records of 110 patients operated between June 2022 and December 2023 at Hospital HM Nou Delfos were reviewed. All patients received standardized OFA, and only the magnesium protocol varied between the groups. The primary objective was to evaluate total morphine consumption during the first 48 hours postoperatively. Secondary outcomes included pain scores, antiemetic use, and adverse events. This study was approved by the hospital's Research Ethics Committee (Protocol V3\_12.05.2025).

Conditions

Postoperative Pain; Obesity; Bariatric Surgery; Opioid-free Anesthesia

Keywords

Magnesium Sulfate; Morphine Consumption; Opioid-Free Anesthesia; TIVA; Multimodal Analgesia

Outcome Measures

Primary Outcomes (1)

• Total postoperative morphine consumption (mg) within 48 hours after surgery

  Total amount of morphine administered within 48 hours after surgery, measured in milligrams, as recorded in the post-anesthesia care unit and hospital stay.

  0-48 hours after surgery

Secondary Outcomes (5)

• Pain intensity using Visual Analog Scale (VAS)

  1, 2, 4, 24, and 48 hours postoperatively

• Incidence of adverse events

  Up to 48 hours after surgery

• Sleep quality reported by the patient

  Within 24 hours after surgery

• Patient satisfaction with anesthesia

  Within 24 hours after surgery

• Length of hospital stay

  Up to 5 days after surgery

Study Arms (2)

TIVA-OFA Mg Bolus

Patients who received a single IV bolus of magnesium sulfate (40 mg/kg) prior to anesthesia induction, as part of an opioid-free total intravenous anesthesia (TIVA) protocol (propofol, dexmedetomidine, lidocaine, ketamine).

TIVA-OFA Mg Bolus + Infusion

Patients who received a bolus of magnesium sulfate (50 mg/kg) followed by a continuous intraoperative infusion (15 mg/kg/h), as part of an opioid-free TIVA protocol (propofol, dexmedetomidine, lidocaine, ketamine).

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Obese adult patients who underwent laparoscopic bariatric surgery under opioid-free total intravenous anesthesia at a single academic center. Participants were retrospectively assigned to one of two magnesium sulfate administration protocols.

You may qualify if:

• Age between 18 and 65 years
• Body mass index (BMI) ≥ 30 kg/m²
• ASA physical status II or III
• Underwent laparoscopic bariatric surgery (sleeve gastrectomy or Roux-en-Y gastric bypass) under opioid-free total intravenous anesthesia

You may not qualify if:

• Pregnancy or breastfeeding
• Chronic opioid use before surgery
• Known allergy to magnesium sulfate or any drug used in the anesthetic protocol
• Severe renal or hepatic insufficiency
• Untreated coagulopathy
• Active substance abuse
• Uncontrolled psychiatric disorders
• Intraoperative complications requiring deviation from the protocol
• Postoperative morphine consumption exceeding institutional standards

Sponsors & Collaborators

• Hospital HM Nou Delfos: lead

Study Sites (1)

Hospital HM Nou Delfos

Barcelona, Barcelona, 08023, Spain

Location

Related Publications (15)

• Alsumali A, Eguale T, Bairdain S, Samnaliev M. Cost-Effectiveness Analysis of Bariatric Surgery for Morbid Obesity. Obes Surg. 2018 Aug;28(8):2203-2214. doi: 10.1007/s11695-017-3100-0.

  PMID: 29335933 BACKGROUND

• Schumann R. Anaesthesia for bariatric surgery. Best Pract Res Clin Anaesthesiol. 2011 Mar;25(1):83-93. doi: 10.1016/j.bpa.2010.12.006.

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• Shariat Moharari R, Motalebi M, Najafi A, Zamani MM, Imani F, Etezadi F, Pourfakhr P, Khajavi MR. Magnesium Can Decrease Postoperative Physiological Ileus and Postoperative Pain in Major non Laparoscopic Gastrointestinal Surgeries: A Randomized Controlled Trial. Anesth Pain Med. 2013 Dec 6;4(1):e12750. doi: 10.5812/aapm.12750. eCollection 2014 Feb.

  PMID: 24660146 BACKGROUND

• Silva Filho SE, Dainez S, Gonzalez MAMC, Angelis F, Vieira JE, Sandes CS. Intraoperative Analgesia with Magnesium Sulfate versus Remifentanil Guided by Plethysmographic Stress Index in Post-Bariatric Dermolipectomy: A Randomized Study. Anesthesiol Res Pract. 2022 Oct 26;2022:2642488. doi: 10.1155/2022/2642488. eCollection 2022.

  PMID: 36339775 BACKGROUND

• Levaux Ch, Bonhomme V, Dewandre PY, Brichant JF, Hans P. Effect of intra-operative magnesium sulphate on pain relief and patient comfort after major lumbar orthopaedic surgery. Anaesthesia. 2003 Feb;58(2):131-5. doi: 10.1046/j.1365-2044.2003.02999.x.

  PMID: 12562408 BACKGROUND

• Albrecht E, Kirkham KR, Liu SS, Brull R. Peri-operative intravenous administration of magnesium sulphate and postoperative pain: a meta-analysis. Anaesthesia. 2013 Jan;68(1):79-90. doi: 10.1111/j.1365-2044.2012.07335.x. Epub 2012 Nov 1.

  PMID: 23121612 BACKGROUND

• De Oliveira GS Jr, Castro-Alves LJ, Khan JH, McCarthy RJ. Perioperative systemic magnesium to minimize postoperative pain: a meta-analysis of randomized controlled trials. Anesthesiology. 2013 Jul;119(1):178-90. doi: 10.1097/ALN.0b013e318297630d.

  PMID: 23669270 BACKGROUND

• Honarmand A, Safavi M, Badiei S, Daftari-Fard N. Different doses of intravenous Magnesium sulfate on cardiovascular changes following the laryngoscopy and tracheal intubation: A double-blind randomized controlled trial. J Res Pharm Pract. 2015 Apr-Jun;4(2):79-84. doi: 10.4103/2279-042X.154365.

  PMID: 25984545 BACKGROUND

• Hansen BA, Bruserud O. Hypomagnesemia in critically ill patients. J Intensive Care. 2018 Mar 27;6:21. doi: 10.1186/s40560-018-0291-y. eCollection 2018.

  PMID: 29610664 BACKGROUND

• Fawcett WJ, Haxby EJ, Male DA. Magnesium: physiology and pharmacology. Br J Anaesth. 1999 Aug;83(2):302-20. doi: 10.1093/bja/83.2.302.

  PMID: 10618948 BACKGROUND

• Murphy JD, Paskaradevan J, Eisler LL, Ouanes JP, Tomas VA, Freck EA, Wu CL. Analgesic efficacy of continuous intravenous magnesium infusion as an adjuvant to morphine for postoperative analgesia: a systematic review and meta-analysis. Middle East J Anaesthesiol. 2013 Feb;22(1):11-20.

  PMID: 23833845 BACKGROUND

• Gozdemir M, Usta B, Demircioglu RI, Muslu B, Sert H, Karatas OF. Magnesium sulfate infusion prevents shivering during transurethral prostatectomy with spinal anesthesia: a randomized, double-blinded, controlled study. J Clin Anesth. 2010 May;22(3):184-9. doi: 10.1016/j.jclinane.2009.06.006.

  PMID: 20400004 BACKGROUND

• Ng KT, Yap JLL, Izham IN, Teoh WY, Kwok PE, Koh WJ. The effect of intravenous magnesium on postoperative morphine consumption in noncardiac surgery: A systematic review and meta-analysis with trial sequential analysis. Eur J Anaesthesiol. 2020 Mar;37(3):212-223. doi: 10.1097/EJA.0000000000001164.

  PMID: 31977626 BACKGROUND

• Kahraman F, Eroglu A. The effect of intravenous magnesium sulfate infusion on sensory spinal block and postoperative pain score in abdominal hysterectomy. Biomed Res Int. 2014;2014:236024. doi: 10.1155/2014/236024. Epub 2014 Mar 19.

  PMID: 24772415 BACKGROUND

• Ahmed SA, Abdelghany MS, Afandy ME. The effect of opioid-free anesthesia on the post-operative opioid consumption in laparoscopic bariatric surgeries: A randomized controlled double-blind study. J Opioid Manag. 2022 Jan-Feb;18(1):47-56. doi: 10.5055/jom.2022.0694.

  PMID: 35238013 BACKGROUND

MeSH Terms

Conditions

Pain, Postoperative; Obesity

Condition Hierarchy (Ancestors)

Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Pain; Neurologic Manifestations; Signs and Symptoms; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight

Study Officials

• Gregory Contreras-Pérez, Anesthesiologist

  Hospital HM Nou Delfos

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Anesthesiologist

Study Record Dates

• First Submitted: July 11, 2025
• First Posted: July 22, 2025
• Study Start: June 1, 2022
• Primary Completion: December 31, 2023
• Study Completion: January 31, 2024
• Last Updated: July 22, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will not share

Locations

ES (1)