Lumbar Spinal StenosisOBESPINENCT07688265
Effect of Obesity Phenotype on Intraabdominal Pressure and Bleeding in Major Lumbar Spinal Surgery
An observational study of Lumbar Spinal Stenosis and Lumbar Degenerative Disease, run by Marmara University Pendik Training and Research Hospital.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Lumbar Spinal Stenosis, Lumbar Degenerative Disease, Obesity
- What is being tested?
- Intraabdominal Pressure Measurement via Urinary Bladder Catheter and Total Intravenous Anesthesia (TIVA)
- Type of treatment
- Injection or infusion
- How many people
- 90 participants
- Where
- No sites listed yet
- Study dates
- 15 Jun 2026to 1 Jun 2027
- Phase
- Observational
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 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
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.
Who may be able to join
- 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
Who cannot join
- - 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
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
Seniyye Ülgen Zengin, Assoc Prof contact
About this study
Official title: Effect of Obesity Phenotype on Intraabdominal Pressure, Intraoperative Bleeding, and Perioperative Complications in Patients Undergoing Major Lumbar Spinal Surgery: A Prospective Observational Study
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)
Read the detailed description
Major lumbar spinal surgery, including lumbar canal stenosis decompression and instrumented fusion, is associated with substantial intraoperative blood loss and notable perioperative morbidity. Obesity is highly prevalent in this patient population due to its role in lumbar degenerative disease pathogenesis. Prone positioning during surgery significantly increases intraabdominal pressure, which in turn may impair venous drainage from the spinal epidural plexus, thereby augmenting operative blood loss. While BMI has been studied as a predictor of spinal surgical outcomes, the differential impact of fat distribution pattern (central vs. peripheral obesity) on IAP dynamics and bleeding has not been adequately characterized.
Study Design:
Prospective, single-center, observational cohort study conducted at Marmara University Pendik Training and Research Hospital and Asaf Ataseven Hospital, Istanbul, Turkey. No interventions beyond routine clinical anesthesia practice will be performed.
Patient Groups:
Patients will be categorized into three groups based on BMI and waist-to-hip ratio (WHR):
- Group NO (Non-obese): BMI <30 kg/m² (n=30)
- Group PO (Peripheral obese): BMI ≥30 kg/m² and WHR <0.85 (n=30)
- Group CO (Central obese): BMI ≥30 kg/m² and WHR ≥0.85 (n=30)
Anesthetic Protocol:
All patients will receive standard intraoperative monitoring (ECG, non-invasive blood pressure, pulse oximetry, end-tidal CO₂, BIS). Anesthesia will be induced with propofol 2 mg/kg, fentanyl 2 µg/kg, and rocuronium 0.6 mg/kg, and maintained with total intravenous anesthesia (TIVA) using propofol and remifentanil infusion, consistent with the institutional protocol for neuromonitoring-guided spinal surgery. Adjusted body weight will be used for drug dosing in obese patients.
Intraabdominal Pressure Measurement:
IAP will be measured via urinary bladder catheter (standard intravesical technique) at three time points: (1) supine position after intubation, (2) prone position, and (3) supine position at the end of surgery.
Data Collection:
Preoperative: age, sex, BMI, weight, height, waist and hip circumferences, WHR, ASA classification, comorbidities, baseline hemogram, BUN, creatinine, INR, aPTT, anticoagulant/antiplatelet use.
Intraoperative: surgical procedure type and level, revision status, anesthesia and surgery duration, neuromonitoring use, hemodynamic parameters at standardized time points, estimated blood loss, fluid and blood product administration, vasopressor/inotrope use, urine output, cell saver use.
Postoperative: hemoglobin and hematocrit drop, BUN, creatinine at 24 hours, Aldrete score, VAS score, ICU admission and indication, postoperative complications (surgical and medical), transfusion requirements, and total hospital length of stay.
Statistical Analysis:
SPSS 21.0 will be used. Continuous variables will be reported as mean ± SD or median (IQR) depending on normality (Kolmogorov-Smirnov/Shapiro-Wilk). Categorical variables will be reported as n (%). Between-group comparisons will employ one-way ANOVA or Kruskal-Wallis test for continuous variables and chi-square or Fisher's exact test for categorical variables. Post-hoc pairwise comparisons will be performed with appropriate correction. Significance threshold: p<0.05.
Sample Size:
Based on published BMI-stratified spinal surgery data, a minimum of 90 patients (30 per group) is required to achieve 80% power at α=0.05 (G*Power 3.1).
- Conditions
- Lumbar Spinal Stenosis, Lumbar Degenerative Disease, Obesity, Intraabdominal Hypertension, Intraoperative Blood Loss, Perioperative Complications
- Being tested
- Intraabdominal Pressure Measurement via Urinary Bladder Catheter, Total Intravenous Anesthesia (TIVA)
- Keywords
- major spinal surgery, obesity phenotype, intraabdominal pressure, intraoperative blood loss, perioperative hemorrhage
- Medical subject headings
- Spinal Stenosis, Obesity, Intra-Abdominal Hypertension
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intraabdominal Pressure Measurement via Urinary Bladder CatheterOther
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.
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)
| Study group | Role | What they receive |
|---|---|---|
| Group 1 - Non-Obese (NO) | BMI <30 kg/m². Adult patients undergoing major lumbar spinal surgery without obesity. Target n=30. Receives: 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. Receives: 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 Receives: Other: Intraabdominal Pressure Measurement via Urinary Bladder Catheter; Other: Total Intravenous Anesthesia (TIVA) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Intraoperative Blood Loss
Total estimated blood loss (mL) calculated from suction canister volume and surgical sponge weight.
Measured: Intraoperative
Intraabdominal Pressure (IAP)
Intravesical IAP measurement (mmHg) via urinary bladder catheter at positional transitions during surgery
Measured: 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
Number of units of packed red blood cells, fresh frozen plasma, and platelet concentrate administered intraoperatively
Measured: Intraoperative
Postoperative Hemoglobin Drop
Difference between preoperative and postoperative hemoglobin levels (g/dL).
Measured: Within 24 hours postoperatively
Vasopressor/Inotrope Requirement
Type and cumulative dose of vasopressor or inotropic agents administered intraoperatively.
Measured: Intraoperative
Postoperative Transfusion Requirement
Postoperative blood product transfusion rate and indication (Hb <7 g/dL, hemodynamic instability, ongoing bleeding).
Measured: up to 7 days postoperatively
Postoperative ICU Admission Rate
Proportion of patients requiring ICU admission and primary indication (hemodynamic instability, respiratory failure, excessive bleeding, neurological complication).
Measured: postoperative day 1
Postoperative Surgical Complications
Wound infection, deep infection, seroma/hematoma, CSF fistula, neurological deficit, revision surgery requirement
Measured: Up to 30 days postoperatively
Postoperative Medical Complications
Acute kidney injury, deep vein thrombosis, pulmonary embolism, pneumonia, atelectasis, cardiac events, delirium, urinary tract infection.
Measured: Up to 30 days postoperatively
Hospital Length of Stay
Total duration of hospital stay in days(up to 30 days postoperatively),
Measured: From surgery to hospital discharge, assessed up to 30 days
Acute Kidney Injury Incidence
Presence of acute kidney injury assessed according to KDIGO (Kidney Disease: Improving Global Outcomes) criteria.
Measured: Time Frame: Within 24 hours postoperatively
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Jul 2026
- Study start15 Jun 2026 (estimated)
- Primary completion1 May 2027 (estimated)
- Study completion1 Jun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Lumbar Spinal StenosisStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Prospective
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Marmara University Pendik Training and Research Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07688265
- Sponsor's protocol ID
- mu anesth
- Acronym
- OBESPINE
- Status last verified
- Jul 2026
- First submitted
- 2 May 2026
- Last updated
- 7 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No