AzTrials
AzTrials

Postoperative PainOFA-MGNCT07077031

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

An observational study of Postoperative Pain and Obesity, run by Hospital HM Nou Delfos at 1 site in Spain.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
Search all trials

Trial 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. Read more about this study

Who is it for?
Ages 18 to 65 years
Conditions the study is for
Postoperative Pain, Obesity, Bariatric Surgery
Type of treatment
Injection or infusion
How many people
110 participants
Where
1 siteSpain
Study dates
1 Jun 2022to 31 Jan 2024
Phase
Observational
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 65 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

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.

Who may be able to join

  • 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

Who cannot join

  • 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
Show all 9Show fewer
  • Uncontrolled psychiatric disorders
  • Intraoperative complications requiring deviation from the protocol
  • Postoperative morphine consumption exceeding institutional standards

Trial locations and contacts

1 site in 1 country.

Spain1 site
  • Hospital HM Nou Delfos

    Barcelona, Barcelona, 08023

Other trials in Spain

About this study

Official title: Comparison of Postoperative Morphine Requirements Between Two Magnesium Sulfate Administration Protocols in Opioid-Free Anesthesia for Bariatric Surgery

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).

Read the detailed description

This is a retrospective, single-center, observational study conducted at Hospital HM Nou Delfos (Barcelona, Spain), which compares the effect of two intravenous magnesium sulfate (MgSO₄) administration protocols on postoperative opioid requirements in patients undergoing bariatric surgery under opioid-free anesthesia (OFA).

The two magnesium protocols evaluated were:

Group A: MgSO₄ bolus 40 mg/kg administered before induction.

Group B: MgSO₄ bolus 50 mg/kg before induction followed by continuous infusion of 15 mg/kg/h until the end of surgery.

All patients underwent standardized OFA including propofol, lidocaine, ketamine and dexmedetomidine. No intraoperative opioids were administered. Multimodal postoperative analgesia was provided in all cases(dexamethasone, paracetamol, and dexketoprofen).

A total of 110 patients were included in the analysis, as defined in the original approved protocol (55 per group).

The primary outcome was cumulative morphine consumption in the first 48 hours postoperatively.

Secondary outcomes included:

Pain scores at rest and with movement at 2, 6, 12, 24, and 48 hours

Use of rescue analgesics

Incidence of postoperative nausea and vomiting (PONV)

Adverse events potentially related to OFA (e.g., hypotension, bradycardia)

Data were extracted from electronic health records and analyzed using descriptive and inferential statistical methods. This study aims to contribute real-world evidence on magnesium strategies in OFA and to support the development of safe, cost-effective analgesic protocols in bariatric patients.

Keywords
Magnesium Sulfate, Morphine Consumption, Opioid-Free Anesthesia, TIVA, Multimodal Analgesia
Medical subject headings
Pain, Postoperative, Obesity

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Study groups in NCT07077031
Study groupRoleWhat they receive
TIVA-OFA Mg BolusPatients 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 + InfusionPatients 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).

What is being measured

The primary outcome is the main question the study is designed to answer.

  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.

    Measured: 0-48 hours after surgery

Secondary outcomes (5)
  1. Pain intensity using Visual Analog Scale (VAS)

    Pain intensity assessed using a 10-point Visual Analog Scale (VAS), where 0 represents no pain and 10 represents the worst imaginable pain.

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

  2. Incidence of adverse events

    Number of patients experiencing side effects such as nausea, vomiting, pruritus, hypotension, bradycardia, ileus, or urinary retention.

    Measured: Up to 48 hours after surgery

  3. Sleep quality reported by the patient

    Patient-reported quality of sleep using a numeric scale from 1 (very poor) to 5 (very good).

    Measured: Within 24 hours after surgery

  4. Patient satisfaction with anesthesia

    Satisfaction assessed using a standardized like scale questionnaire (1 = very dissatisfied, 5 = very satisfied).

    Measured: Within 24 hours after surgery

  5. Length of hospital stay

    Total number of days from surgery to discharge, extracted from medical records.

    Measured: Up to 5 days after surgery

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted22 Jul 2025
  2. Study start1 Jun 2022
  3. Primary completion31 Dec 2023
  4. Study completion31 Jan 2024

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Observational
Observational model
Cohort
Time perspective
Retrospective
Enrolment
110 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07077031
Sponsor's protocol ID
25.04.2520-GHM
Acronym
OFA-MG
Status last verified
Jul 2025
First submitted
11 Jul 2025
Last updated
22 Jul 2025
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No: Individual participant data will not be shared due to privacy regulations and ethical considerations. The dataset contains sensitive health information from a retrospective analysis and cannot be anonymized to the level required for public release. Access will be limited to the research team and authorized personnel as approved by the ethics committee.

Publications

  • 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.

    PubMed 29335933
  • 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.

    PubMed 21516916
  • 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.

    PubMed 24660146
  • 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.

    PubMed 36339775
  • 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.

    PubMed 12562408
  • 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.

    PubMed 23121612
  • 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.

    PubMed 23669270
  • 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.

    PubMed 25984545
  • 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.

    PubMed 29610664
  • 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.

    PubMed 10618948
  • 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.

    PubMed 23833845
  • 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.

    PubMed 20400004
  • 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.

    PubMed 31977626
  • 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.

    PubMed 24772415
  • 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.

    PubMed 35238013

Questions about this trial

What is this clinical trial studying?

An observational study of Postoperative Pain and Obesity, run by Hospital HM Nou Delfos at 1 site in Spain.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 22 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Spain. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Total postoperative morphine consumption (mg) within 48 hours after surgery (time frame: 0-48 hours after surgery). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07077031, which also lists 15 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Jul 2025.

Free account

Log in to keep searching

You’ve used your 3 free searches. AzTrials is free: log in or create a free account to keep searching clinical trials and save the ones you want to follow.

Create a free accountLog in