Comparison of 5 vs 8 cmH₂O PEEP on Respiratory Mechanics in Prone Lumbar Surgery (PROPEEP)

The Effect of Different PEEP Levels Accompanied by PCV-VG Mode on Respiratory Mechanics and Gas Exchange in Lumbar Surgeries Performed in the Prone Position Under TIVA

This randomized controlled clinical trial aims to compare the effects of two different positive end-expiratory pressure (PEEP) levels (5 cmH₂O and 8 cmH₂O) on respiratory mechanics in patients undergoing lumbar spine surgery in the prone position under total intravenous anesthesia (TIVA). Prone positioning may adversely affect lung compliance and gas exchange, making optimal ventilatory strategies essential. Driving pressure and mechanical power are considered key determinants of ventilator-induced lung stress. This study will evaluate the impact of different PEEP levels on respiratory parameters and intraoperative physiological changes.

Study Overview

• Status: Not yet recruiting
• Conditions: Lumbar Disc Herniation; General Anesthesia; Prone Position; Spinal Surgery
• Intervention / Treatment: Device: Mechanical Ventilation (PEEP)

Detailed Description

Prone positioning during lumbar spine surgery is associated with increased intrathoracic pressure, reduced lung compliance, and impaired ventilation-perfusion matching, which may negatively affect respiratory mechanics and gas exchange. Mechanical ventilation strategies, particularly the application of positive end-expiratory pressure (PEEP), play a critical role in preventing atelectasis and optimizing oxygenation.

Pressure-controlled ventilation with volume guarantee (PCV-VG) is a modern ventilation mode that ensures target tidal volume delivery while minimizing airway pressures, thereby reducing the risk of ventilator-induced lung injury. In recent years, driving pressure (ΔP) and mechanical power have emerged as important parameters reflecting lung stress and injury during mechanical ventilation.

This prospective randomized controlled trial aims to evaluate the effects of two different PEEP levels (5 cmH₂O and 8 cmH₂O) on respiratory mechanics and gas exchange in patients undergoing lumbar spine surgery in the prone position under total intravenous anesthesia (TIVA). Patients will be randomly assigned into two groups receiving either 5 cmH₂O or 8 cmH₂O PEEP. Ventilation will be standardized using PCV-VG mode with a tidal volume of 6-8 mL/kg predicted body weight and respiratory rate adjusted to maintain normocapnia.

Hemodynamic parameters and respiratory variables, including peak airway pressure, plateau pressure, dynamic compliance, airway resistance, tidal volume, and end-tidal CO₂, will be recorded at predefined time points. Arterial blood gas analyses will be performed at selected intervals to assess gas exchange.

The primary outcome of the study is driving pressure (ΔP), while secondary outcomes include mechanical power, oxygenation parameters, PaCO₂-EtCO₂ gradient, and physiologic dead space fraction (VD/VT).

The findings of this study are expected to provide clinical evidence regarding the optimal PEEP level in prone lumbar surgery and contribute to improving intraoperative lung-protective ventilation strategies.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Basak Pehlivan, Assoc Prof; Phone Number: 5054083199; Email: bpehlivan@harran.edu.tr
• Study Contact Backup: Name: Veli F Pehlivan, MD; Phone Number: 5327696566; Email: vfpehlivan@harran.edu.tr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients aged between 18 and 65 years
• American Society of Anesthesiologists (ASA) physical status I-II
• Scheduled for elective lumbar spine surgery in the prone position
• Planned general anesthesia with total intravenous anesthesia (TIVA)
• Ability to provide informed consent

Exclusion Criteria:

• Body mass index (BMI) ≥ 30 kg/m²
• History of significant pulmonary disease (e.g., COPD, asthma)
• Severe cardiovascular disease
• Pregnancy
• Known difficult airway
• Requirement for intraoperative vasopressor infusion due to hemodynamic instability
• Conversion to different surgical position or change in surgical plan
• Incomplete data or protocol deviation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: PEEP-5 Group; Participants in this group will receive mechanical ventilation with a positive end-expiratory pressure (PEEP) level of 5 cmH₂O during lumbar spine surgery in the prone position under total intravenous anesthesia (TIVA). Ventilation will be performed using PCV-VG mode with a target tidal volume of 6-8 mL/kg predicted body weight and respiratory rate adjusted to maintain normocapnia.	Device: Mechanical Ventilation (PEEP); Mechanical ventilation will be applied using pressure-controlled ventilation with volume guarantee (PCV-VG) mode during prone lumbar surgery under total intravenous anesthesia (TIVA). Two different positive end-expiratory pressure (PEEP) levels (5 cmH₂O and 8 cmH₂O) will be used according to group allocation. Tidal volume will be set at 6-8 mL/kg predicted body weight, and respiratory rate will be adjusted to maintain normocapnia (EtCO₂ 35-40 mmHg).; Other Names: Lung Protective Ventilation; PCV-VG Ventilation
Experimental: PEEP-8 Group; Participants in this group will receive mechanical ventilation with a positive end-expiratory pressure (PEEP) level of 8 cmH₂O during lumbar spine surgery in the prone position under total intravenous anesthesia (TIVA). Ventilation will be performed using PCV-VG mode with a target tidal volume of 6-8 mL/kg predicted body weight and respiratory rate adjusted to maintain normocapnia.	Device: Mechanical Ventilation (PEEP); Mechanical ventilation will be applied using pressure-controlled ventilation with volume guarantee (PCV-VG) mode during prone lumbar surgery under total intravenous anesthesia (TIVA). Two different positive end-expiratory pressure (PEEP) levels (5 cmH₂O and 8 cmH₂O) will be used according to group allocation. Tidal volume will be set at 6-8 mL/kg predicted body weight, and respiratory rate will be adjusted to maintain normocapnia (EtCO₂ 35-40 mmHg).; Other Names: Lung Protective Ventilation; PCV-VG Ventilation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Driving Pressure (ΔP)	Driving pressure (ΔP), calculated as the difference between plateau pressure (Pplat) and positive end-expiratory pressure (PEEP), will be used as the primary outcome to assess lung stress during mechanical ventilation.	Intraoperative period (at predefined time points: T0, T2, T5)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mechanical Power	Mechanical power will be calculated to quantify the energy delivered to the respiratory system during mechanical ventilation.	Intraoperative period (T0, T2, T5)
Oxygenation (PaO₂/FiO₂ Ratio)	Oxygenation status will be assessed using the arterial oxygen partial pressure to inspired oxygen fraction (PaO₂/FiO₂) ratio.	Intraoperative period (T0, T2, T5)
PaCO₂-EtCO₂ Gradient	The difference between arterial carbon dioxide pressure (PaCO₂) and end-tidal CO₂ (EtCO₂) will be used to evaluate ventilation-perfusion mismatch.	Intraoperative period (T0, T2, T5)
Physiological Dead Space Fraction (VD/VT)	Physiological dead space fraction will be calculated using the Bohr equation to assess ventilation efficiency.	Intraoperative period (T0, T2, T5)
Dynamic Lung Compliance (Cdyn)	Dynamic compliance will be recorded to evaluate changes in lung mechanics during ventilation.	Intraoperative period (all time points)
Peak Airway Pressure (Ppeak)	Peak airway pressure will be recorded to assess airway pressure changes during mechanical ventilation.	Intraoperative period (all time points)

Collaborators and Investigators

• Sponsor: Harran University
• Investigators: Principal Investigator: Basak Pehlivan, Asoc Prof, Harran University Faculty of Medicine, Department of Anesthesiology

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): July 2, 2026
• Study Completion (Estimated): September 3, 2026

Study Registration Dates

• First Submitted: April 16, 2026
• First Submitted That Met QC Criteria: April 16, 2026
• First Posted (Actual): April 22, 2026

Study Record Updates

• Last Update Posted (Actual): April 29, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Prone Position; PEEP; Lung Protective Ventilation; Mechanical Power; Driving Pressure; PCV-VG Ventilation
• Additional Relevant MeSH Terms: Bone Diseases; Musculoskeletal Diseases; Pathological Conditions, Anatomical; Spinal Diseases; Hernia; Pathological Conditions, Signs and Symptoms; Intervertebral Disc Displacement; Therapeutics; Airway Management; Resuscitation; Emergency Treatment; Respiratory Therapy; Respiration, Artificial; Positive-Pressure Respiration
• Other Study ID Numbers: REŞIT-PEEP-2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No