Bariatric Surgery, Obesity, Opioid-free Anesthesia, Postoperative Pain
Conditions
Keywords
Magnesium Sulfate, Morphine Consumption, Opioid-Free Anesthesia, TIVA, Multimodal Analgesia
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).
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.
Interventions
None listed
Sponsors
Hospital HM Nou Delfos
Study design
Observational model
COHORT
Time perspective
RETROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
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
Exclusion criteria
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Total postoperative morphine consumption (mg) within 48 hours after surgery | 0-48 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Pain intensity using Visual Analog Scale (VAS) | 1, 2, 4, 24, and 48 hours postoperatively | Pain intensity assessed using a 10-point Visual Analog Scale (VAS), where 0 represents no pain and 10 represents the worst imaginable pain. |
| Incidence of adverse events | Up to 48 hours after surgery | Number of patients experiencing side effects such as nausea, vomiting, pruritus, hypotension, bradycardia, ileus, or urinary retention. |
| Sleep quality reported by the patient | Within 24 hours after surgery | Patient-reported quality of sleep using a numeric scale from 1 (very poor) to 5 (very good). |
| Patient satisfaction with anesthesia | Within 24 hours after surgery | Satisfaction assessed using a standardized like scale questionnaire (1 = very dissatisfied, 5 = very satisfied). |
| Length of hospital stay | Up to 5 days after surgery | Total number of days from surgery to discharge, extracted from medical records. |
Countries
Spain
Outcome results
None listed