Effect of Obesity Phenotype on Intraabdominal Pressure and Bleeding in Major Lumbar Spinal Surgery

NCT07688265 | Not Yet Recruiting

• 1 other identifier: mu anesth
• Study Type: observational
• Target: 90
• Locations: 0 countries
• Sites: N/A

Brief Summary

Obesity is prevalent among patients with lumbar degenerative disease and is a known risk factor for perioperative complications in spinal surgery. However, most existing evidence relies solely on body mass index (BMI) without distinguishing between central and peripheral obesity phenotypes. Central and peripheral fat distribution may have distinct biomechanical and hemodynamic consequences, particularly with respect to intraabdominal pressure (IAP) changes during prone positioning and intraoperative blood loss. This prospective single-center observational study aims to evaluate the effect of obesity phenotype - classified as non-obese, centrally obese, or peripherally obese based on BMI and waist-to-hip ratio - on intraabdominal pressure, intraoperative blood loss, and other perioperative outcomes in adult patients undergoing major lumbar spinal surgery (decompression and/or instrumentation)

Conditions

Lumbar Spinal Stenosis; Obesity; Intraabdominal Hypertension; Perioperative Complications; Intraoperative Blood Loss; Lumbar Degenerative Disease

Keywords

major spinal surgery; obesity phenotype; intraabdominal pressure; intraoperative blood loss; perioperative hemorrhage

Outcome Measures

Primary Outcomes (2)

• Intraoperative Blood Loss

  Total estimated blood loss (mL) calculated from suction canister volume and surgical sponge weight.

  Intraoperative

• Intraabdominal Pressure (IAP)

  Intravesical IAP measurement (mmHg) via urinary bladder catheter at positional transitions during surgery

  Three intraoperative time points from beginning to end: 1.supine after intubation, 2.prone position, and 3.supine at end of surgery

Secondary Outcomes (9)

• Intraoperative Transfusion Requirement

  Intraoperative

• Postoperative Hemoglobin Drop

  Within 24 hours postoperatively

• Vasopressor/Inotrope Requirement

  Intraoperative

• Postoperative Transfusion Requirement

  up to 7 days postoperatively

• Postoperative ICU Admission Rate

  postoperative day 1

Study Arms (3)

Group 1 - Non-Obese (NO)

BMI \<30 kg/m². Adult patients undergoing major lumbar spinal surgery without obesity. Target n=30.

Other: Intraabdominal Pressure Measurement via Urinary Bladder Catheter; Other: Total Intravenous Anesthesia (TIVA)

Group 2 - Peripheral Obese (PO)

BMI ≥30 kg/m² and waist-to-hip ratio \<0.85. Patients with predominantly peripheral (gynoid) fat distribution. Target n=30.

Other: Intraabdominal Pressure Measurement via Urinary Bladder Catheter; Other: Total Intravenous Anesthesia (TIVA)

Group 3 - Central Obese (CO)

BMI ≥30 kg/m² and waist-to-hip ratio ≥0.85. Patients with predominantly central (android) fat distribution. Target n=30

Other: Intraabdominal Pressure Measurement via Urinary Bladder Catheter; Other: Total Intravenous Anesthesia (TIVA)

Interventions

Intraabdominal Pressure Measurement via Urinary Bladder Catheter OTHER

Intravesical intraabdominal pressure measurement performed via indwelling urinary catheter at three standardized time points: supine position after intubation, prone position during surgery, and supine position at end of surgery. This measurement is performed as part of observational data collection within the scope of routine catheterization; no additional invasive procedure is applied.

Group 1 - Non-Obese (NO); Group 2 - Peripheral Obese (PO); Group 3 - Central Obese (CO)

Total Intravenous Anesthesia (TIVA) OTHER

Standardized TIVA protocol applied uniformly to all patients per institutional neuromonitoring-guided spinal surgery protocol. Induction with propofol 2 mg/kg, fentanyl 2 µg/kg, and rocuronium 0.6 mg/kg; maintenance with propofol and remifentanil infusion. Adjusted body weight used for drug dosing in obese patients. No study-specific modification to routine anesthetic management is performed. Arm Label: All Groups (NO, PO, CO)

Group 1 - Non-Obese (NO); Group 2 - Peripheral Obese (PO); Group 3 - Central Obese (CO)

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Adult patients aged 18-80 years with ASA physical status I-III scheduled for elective major lumbar spinal surgery (decompression and/or instrumentation) at Marmara University Pendik Training and Research Hospital and Asaf Ataseven Hospital, Istanbul, Turkey. Patients are classified by obesity phenotype based on BMI and waist-to-hip ratio. Patients with renal failure, coagulation disorders, anemia, pregnancy, prior lumbar surgery, or emergency procedures are excluded.

You may qualify if:

• Age 18-80 years
• ASA Physical Status Classification I-III
• Scheduled for elective major lumbar spinal surgery (canal stenosis decompression and/or instrumented fusion)
• No prior lumbar spinal surgery
• Written informed consent obtained

You may not qualify if:

• \- Pediatric patients (\<18 years)
• Pregnancy
• Emergency surgical procedures
• Pre-existing renal failure
• Coagulation disorder
• Pre-existing anemia
• Known drug allergy relevant to study medications
• Inability to obtain written informed consent

Sponsors & Collaborators

• Marmara University Pendik Training and Research Hospital: lead

MeSH Terms

Conditions

Spinal Stenosis; Obesity; Intra-Abdominal Hypertension

Condition Hierarchy (Ancestors)

Spinal Diseases; Bone Diseases; Musculoskeletal Diseases; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Compartment Syndromes; Muscular Diseases; Vascular Diseases; Cardiovascular Diseases

Central Study Contacts

Dilara Göçmen, asst prof

CONTACT

+90 216 625 45 45; dilara.gocmen@marmara.edu.tr

Seniyye Ülgen Zengin, Assoc Prof

CONTACT

szengin@marmara.edu.tr

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 2, 2026
• First Posted: July 7, 2026
• Study Start: June 15, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): June 1, 2027
• Last Updated: July 7, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share