An observational study in Lumbar Spinal Stenosis, Lumbar Degenerative Disease and Obesity, sponsored by Marmara University Pendik Training and Research Hospital. Not yet recruiting. Open to participants aged 18 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by Marmara University Pendik Training and Research Hospital · Observational
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)
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):
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).
458 studies on the registry are indexed under Spinal Stenosis; 105 are open to participants now.
This study's planned enrollment of 90 is below the median of 120 across 154 observational studies indexed under Spinal Stenosis.
Browse Spinal Stenosis studies →Marmara University Pendik Training and Research Hospital is the lead sponsor of 34 studies on the registry; 15 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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)
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)
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)
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.
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)
Intraoperative Blood Loss
Total estimated blood loss (mL) calculated from suction canister volume and surgical sponge weight.
Time frame: Intraoperative
Intraabdominal Pressure (IAP)
Intravesical IAP measurement (mmHg) via urinary bladder catheter at positional transitions during surgery
Time frame: Three intraoperative time points from beginning to end: 1.supine after intubation, 2.prone position, and 3.supine at end of surgery
Intraoperative Transfusion Requirement
Number of units of packed red blood cells, fresh frozen plasma, and platelet concentrate administered intraoperatively
Time frame: Intraoperative
Postoperative Hemoglobin Drop
Difference between preoperative and postoperative hemoglobin levels (g/dL).
Time frame: Within 24 hours postoperatively
Vasopressor/Inotrope Requirement
Type and cumulative dose of vasopressor or inotropic agents administered intraoperatively.
Time frame: Intraoperative
Postoperative Transfusion Requirement
Postoperative blood product transfusion rate and indication (Hb \<7 g/dL, hemodynamic instability, ongoing bleeding).
Time frame: 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).
Time frame: postoperative day 1
Postoperative Surgical Complications
Wound infection, deep infection, seroma/hematoma, CSF fistula, neurological deficit, revision surgery requirement
Time frame: Up to 30 days postoperatively
Postoperative Medical Complications
Acute kidney injury, deep vein thrombosis, pulmonary embolism, pneumonia, atelectasis, cardiac events, delirium, urinary tract infection.
Time frame: Up to 30 days postoperatively
Hospital Length of Stay
Total duration of hospital stay in days(up to 30 days postoperatively),
Time frame: 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.
Time frame: Time Frame: Within 24 hours postoperatively
No study locations are listed for this record.
Plan to share: No
No publications or documents are linked to this record.
Start is estimated for Jun 2026; primary completion for May 2027, 10 months later.
Of 62 non-industry observational studies under Spinal Stenosis, half reached primary completion within 43 months of starting (the median), counting those still running; a quarter within 21 and three quarters within 84. This study's planned 10 months is below that.
Counting every sponsor, half of 78 studies reached it within 51 months; a quarter within 23 and three quarters within 84.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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Marmara University Pendik Training and Research Hospital