Dynamic Compliance-Guided Ventilation in Lumbar Surgery

Summary

Postoperative pulmonary complications are a frequent cause of morbidity following lumbar stabilization surgery. Conventional ventilation strategies may not adequately reflect intraoperative changes in respiratory mechanics, potentially leading to impaired postoperative pulmonary function. Dynamic compliance-guided ventilation provides a real-time, individualized approach by adjusting ventilatory parameters according to lung compliance.

This prospective randomized controlled study aims to evaluate the effects of dynamic compliance-guided ventilation compared with standard ventilation strategies on postoperative pulmonary function in patients undergoing lumbar stabilization surgery. Eligible patients will be randomly assigned to either the compliance-guided group or the conventional ventilation group.

In this study, the investigators aim to prospectively compare ventilation with the dynamic compliance (Cdyn) approach-one of the lung-protective ventilation strategies-with conventional ventilation methods in patients undergoing surgery in the prone position. The primary outcome will be evaluated using a modified lung ultrasound scoring system based on the most severely affected regions of aeration loss. Secondary objectives include the assessment of intraoperative hemodynamics, respiratory mechanics, and the effects on postoperative pulmonary function.

Conditions

• Lumbar Spine Stenosis
• Lumbar Disc Herniation
• Ventilator-Induced Lung Injury
• Postoperative Complications

Interventions

PROCEDURE

Dynamic Compliance Guided Ventilation

After intubation and prone positioning, both groups will undergo the same initial recruitment maneuver as described above. In the dynamic compliance-guided group, positive end expiratory pressure(PEEP) will then be titrated according to dynamic compliance (Cdyn = VT / \[Ppeak - PEEP\])(Ppeak: Peak airway pressure)(VT:Tidal volume). Tidal volume will be set at 7 ml/kg, respiratory rate 12/min, and positive end expiratory pressure(PEEP) reduced stepwise from 20 cmH₂O to 5 cmH₂O in increments of 2 cmH₂O. Each positive end expiratory pressure(PEEP) level (19, 17, 15, 13, 11, 9, 7, 5 cmH₂O) will be maintained for 10 respiratory cycles, with Cdyn measured at the end of each level. The positive end expiratory pressure(PEEP) corresponding to the highest dynamic compliance will be selected and maintained throughout the surgery.In both groups, a 30% t-pause will be applied throughout the operation after intubation. Patients will be ventilated in volume-controlled ventilation (VCV) mode.

PROCEDURE

Standard Ventilation

After intubation, both groups will initially receive conventional ventilation in volume-controlled mode with a tidal volume of 7 ml/kg (predicted body weight), positive end expiratory pressure(PEEP) of 5 cmH₂O, and an inspiratory-to-expiratory ratio of 1:2. Respiratory rate will be adjusted to maintain end-tidal CO₂ between 35-45 mmHg. Following prone positioning, a recruitment maneuver will be performed using pressure-controlled ventilation, gradually increasing positive end expiratory pressure(PEEP) from 5 to 20 cmH₂O and holding for 20 seconds. After recruitment, the standard ventilation group will continue with the initial ventilator settings until the end of the surgery. Patients will be ventilated in volume-controlled ventilation (VCV) mode.

Sponsors & Collaborators

• Ankara City Hospital Bilkent

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

OTHER

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-01-22

Primary Completion

2026-05-20

Completion

2026-06-01

Countries

• Turkey (Türkiye)

Study Locations