Effort, Mechanical Ventilation, Respiratory Failure
Conditions
Keywords
Assisted mechanical ventilation, Inspiratory Effort, Breathing effort
Brief summary
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.
Interventions
OTHERPEEP Level Adjustment
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.
Sponsors
Pontificia Universidad Catolica de Chile
Clínica Universidad de los Andes
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
NONE
Intervention model description
After informed consent is obtained, participants admitted to the ICU of Hospital Clínico UC or Clínica Universidad de los Andes and receiving invasive mechanical ventilation will undergo a randomized physiological crossover intervention. Pressure support will remain unchanged throughout the study and will be maintained at the level programmed by the treating medical team prior to study initiation. Four predefined levels of positive end-expiratory pressure (PEEP: 0, 5, 10, and 15 cmH₂O) will be applied in a randomized sequence, each lasting 15 minutes. Between each PEEP level, a 15-minute washout period will be performed using the same PEEP level set by the treating medical team before the intervention. During the final 5 minutes of each PEEP stage, physiological measurements of respiratory effort will be recorded. If clinical instability occurs, the intervention will be stopped and ventilator settings will be returned to baseline.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Pressure-time product per minute (PTPmin) | During the last 5 minutes of each PEEP level | Pressure-time product per minute (PTPmin), expressed as cmH₂O·s/min, measured using an esophageal balloon catheter as an index of global inspiratory effort. |
| Delta Pocc (ΔPocc) | During the last 5 minutes of each PEEP level | Airway occlusion pressure-derived index (ΔPocc) obtained from brief ventilator-based airway occlusion maneuvers as a non-invasive measurement of inspiratory effort. |
| Muscular Pressure Index (PMI) | During the last 5 minutes of each PEEP level | Muscular Pressure Index (PMI) calculated from ventilator-based airway occlusion maneuvers as a non-invasive estimate of inspiratory muscle pressure. |
| Esophageal pressure swing (ΔPes) | During the last 5 minutes of each PEEP level | Esophageal pressure swing (ΔPes), defined as the absolute difference between end-expiratory and end-inspiratory esophageal pressure, measured using an esophageal balloon catheter. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Hemodynamic response | During the last 5 minutes of each PEEP level | Hemodynamic response assessed using heart rate, arterial blood pressure, respiratory rate and oxygen saturation during assisted mechanical ventilation at different PEEP levels. |
| Gas exchange (SaFi index) | During the last 5 minutes of each PEEP level | Gas exchange assessed using the SaFi index (SpO₂/FiO₂ ratio) at each PEEP level. |
| Driving pressure | During the last 5 minutes of each PEEP level | Driving pressure calculated as the difference between airway plateau pressure and total PEEP during assisted mechanical ventilation at each PEEP level. |
| Dynamic transpulmonary pressure | During the last 5 minutes of each PEEP level | ynamic transpulmonary pressure calculated during assisted mechanical ventilation using airway pressure and esophageal pressure measurements obtained with an esophageal balloon catheter. |
| Plateau pressure | During the last 5 minutes of each PEEP level | Airway plateau pressure measured during assisted mechanical ventilation at each PEEP level. |
| Airway occlusion pressure at 100 ms (P0.1) | During the last 5 minutes of each PEEP level | Airway occlusion pressure at 100 milliseconds (P0.1), measured by the mechanical ventilator as an index of respiratory drive. |
| Respiratory system compliance (Cest) | During the last 5 minutes of each PEEP level | Static compliance of the respiratory system (Cest) measured during assisted mechanical ventilation at each PEEP level. |
Countries
Chile
Contacts
CONTACTDiego Lopez Arnello, Physioterapy
CONTACTFelipe Damiani, PhD, Msc, Physioterapy
PRINCIPAL_INVESTIGATORRoque Basoalto, PhD, Msc, Physioterapy
Pontifica Universidad Catolica de Chile
STUDY_CHAIRSebastian Morales, Physician
Pontifica Universidad Catolica de Chile
PRINCIPAL_INVESTIGATORAlejandro Bruh Bruhn
Pontifica Universidad Catolica de Chile
Outcome results
None listed