Impact of PEEP on Respiratory Effort During Assisted Ventilation

Pontificia Universidad Catolica de Chile12 enrolled

Overview

Assisted mechanical ventilation is widely used to preserve diaphragmatic activity and improve lung aeration in patients with acute respiratory failure. However, during assisted ventilation, excessive inspiratory effort may develop and contribute to lung injury, diaphragmatic overload, and patient self-inflicted lung injury. Optimizing ventilator settings to modulate respiratory effort therefore represents a major physiological and clinical challenge. Positive end-expiratory pressure (PEEP) is a key determinant of lung recruitment and respiratory system mechanics and may influence inspiratory effort by modifying lung volume, compliance, and respiratory drive. Despite its widespread use, PEEP titration in clinical practice is still mainly guided by oxygenation parameters, while its direct effects on inspiratory effort during assisted mechanical ventilation remain insufficiently characterized. This physiological randomized crossover study aims to evaluate the effect of four predefined levels of positive end-expiratory pressure (0, 5, 10, and 15 cmH₂O) on the respiratory system and inspiratory effort in adult patients receiving assisted mechanical ventilation. Patients will be exposed to each PEEP level in randomized order, with stabilization and washout periods between conditions, while ventilatory support settings other than PEEP are kept constant.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

OTHER

Masking

NONE

Enrollment

Conditions

Mechanical Ventilation

Interventions

PEEP Level AdjustmentOTHER

Positive end-expiratory pressure (PEEP) will be adjusted to four predefined levels (0, 5, 10, and 15 cmH₂O) following a randomized crossover protocol during assisted mechanical ventilation. Only the PEEP level will be modified, while all other ventilator settings will be kept constant. Each PEEP level will be maintained for 15 minutes, followed by a 15-minute washout period between levels. Physiological measurements will be obtained during the last 5 minutes of each PEEP level, including respiratory effort assessed using invasive and non-invasive methods, respiratory mechanics, and hemodynamic parameters.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion criteria: * Age ≥18 years. * ICU patients receiving invasive mechanical ventilation (endotracheal tube or tracheostomy). * Ventilated in an assisted mode with spontaneous breathing * Clinically stable to undergo protocolized PEEP changes. * Sedation level compatible with spontaneous breathing and ventilator triggering * Informed consent from the patient or legally authorized representative. Exclusion Criteria: * Contraindication to esophageal balloon placement (if applicable). * Significant hemodynamic instability or unstable vasopressor requirements. * Unstable arrhythmia or active myocardial ischemia. * Undrained pneumothorax or major air leak. * Controlled ventilation without effective spontaneous effort (apnea, neuromuscular blockade, deep sedation). * Pregnancy * Acute or chronic neurological conditions that may impair respiratory drive or interfere with the regulation of spontaneous breathing.

Outcomes

Primary Outcomes

Esophageal pressure swing (ΔPes)

Esophageal pressure swing (ΔPes), defined as the absolute difference between end-expiratory and end-inspiratory esophageal pressure, measured using an esophageal balloon catheter.