ARDS (Acute Respiratory Distress Syndrome), Pneumonia, Respiratory Failure, Respiratory Insufficiency
Conditions
Keywords
Positive end-expiratory pressure, PEEP, pressure support ventilation, assisted breathing, Inspiratory effort, Inspiratory drive, Ventilation efficiency, Diaphragm
Brief summary
The goal of this interventional study is to evaluate the effect of different positive end-expiratory pressures (PEEP) on lung and diaphragm function in patients mechanically ventilated with pressure support ventilation in the intensive care unit. The main questions aim to answer: Does higher PEEP level affect diaphragm contractions and ventilatory efficiency? Does higher PEEP level limit inspiratory efforts? Does higher PEEP level affect lung compliance? The participants will be subjected to three different PEEP levels during pressure support ventilation: Low PEEP (4 cmH2O), Medium PEEP (10 cmH2O), High PEEP (16 cmH2O). The lung and diaphragm function will be evaluated using high-resolution esophageal manometry, electrical activity of the diaphragm, external diaphragm ultrasound and spirometric ventilator data.
Interventions
PROCEDURELow positive end-expiratory pressure
Low (4 cmH2O) positive end-expiratory pressure (PEEP) will be applied during pressure support ventilation. The PEEP level will be kept for 10 minutes prior to data acquisition.
PROCEDUREMedium positive end-expiratory pressure
Medium (10 cmH2O) positive end-expiratory pressure (PEEP) will be applied during pressure support ventilation. The PEEP level will be kept for 10 minutes prior to data acquisition.
PROCEDUREHigh positive end-expiratory pressure
High(16 cmH2O) positive end-expiratory pressure (PEEP) will be applied during pressure support ventilation. The PEEP level will be kept for 10 minutes prior to data acquisition.
Sponsors
Vastra Gotaland Region
Sahlgrenska University Hospital
Göteborg University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
SUPPORTIVE_CARE
Masking
SINGLE (Subject)
Intervention model description
Randomized interventional crossover study
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Mechanical ventilation with pressure support or mechanical ventilation with possibility to transition to pressure support * Oxygen requirement ≤ 50% * Pressure support ≤ 12 cmH2O * PEEP ≤ 12 cmH2O * Age ≥ 18 years * Adequate intravascular volume status
Exclusion criteria
* Circulatory instability * Brain death diagnosis/brain death evaluation * Norepinephrine dose \> 0.4 µg/kg/min * Muscle relaxation administered within 2 hours * Pregnancy * Contraindication to esophageal catheterization (e.g., esophageal varices) * Conditions with increased risk of pneumothorax (such as severe COPD (Chronic Obstructive Pulmonary Disease) or extensive emphysema) * Untreated pneumothorax * Symptomatic airway obstruction Discontinuation criteria during ongoing study intervention: * Heart rate \> 120 beats/min * Systolic blood pressure \> 180 mmHg * Inspired oxygen fraction \> 70% * Respiratory rate \> 35/min * RASS (Richmond Agitation Sedation Scale) ≥ 2 * Doubling of norepinephrine dose or increase of norepinephrine dose to \> 0.5 µg/kg/min to maintain mean arterial pressure * Bradycardia \< 45 beats/min
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Inspiratory effort | Measured during 5 uninterrupted breaths 10 minutes after application of interventional PEEP level | Inspiratory effort will be measured by the tidal change in esophageal pressure (in cmH2O) during assisted breathing. The esophageal pressure will be measured using a high-resolution manometry catheter. The change from expiratory to inspiratory esophageal pressure will represent the tidal change and be used to estimate the inspiratory effort. |
| Inspiratory drive | Measured during 5 uninterrupted breaths 10 minutes after application of interventional PEEP level | The electric activity of the diaphragm (Eadi) will be measured using a NAVA (neurally adjusted ventilatory assist) catheter. The change from end-expiratory to inspiratory Eadi will be calculated. This represents the inspiratory drive. The Eadi will be measured in Voltage. |
| Effort-to-drive ratio | Calculated from the measures collected 10 minutes after application of interventional PEEP level | The effort-to-drive ratio (EDR) will be calculated as the inspiratory effort (tidal change in esophageal pressure) divided by the inspiratory drive (tidal change in electric activity of the diaphragm). |
| Neuromechanical efficiency | Calculated from the measures collected during the occlusion manoeuvre performed 10-15 minutes after application of interventional PEEP level | The neuromechanical efficiency will be calculated as the change in airway pressure during an occlusion test (Pocc) (measured from end-expiration to maximum negative pressure during the occlusion manoeuvre) divided by the inspiratory change in electric activity of the diaphragm (from end-expiration to inspiration). |
| Thickening fraction of the diaphragm (TFdi) | Measured 10 minutes after application of interventional PEEP level | Measured by ultrasound at the right hemidiaphragm. The thickening fraction of the diaphragm (TFdi) will be calculated as \[ (end-inspiratory diaphragm thickness - end-expiratory diaphragm thickness) / end-expiratory diaphragm thickness) \]. |
| Transpulmonary driving pressure | Measured during 5 breaths 10 minutes after application of interventional PEEP level | Change in transpulmonary pressure ( airway pressure - esophageal pressure) from end-expiration to end-inspiration will be calculated using ventilator data and high-resolution manometry |
| Occlusion pressure | The occlusion pressure will be measured during an occlusion manoeuvre performed 10-15 minutes after application of interventional PEEP level. | The airway pressure drop from end-expiration to minimum pressure during an occlusion manoeuvre will be measured using the ventilator. The pressure drop indicates the inspiratory effort. It will be measured in cmH2O. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Airway driving pressure | Measured during an inspiratory hold performed 10-15 minutes after application of interventional PEEP level | Difference in airway pressure between end-expiration and during an inspiratory hold will be calculated from the ventilator data. |
| Lung compliance | Measured during an inspiratory hold performed 10 - 15 minutes after application of interventional PEEP level | Lung compliance will be calculated as the tidal volume divided by the change in transpulmonary pressure from end-expiration to end-inspiration. |
| Thickening fraction of the expiratory abdominal muscles (TFabd) | Measured 10 minutes after application of interventional PEEP level | The abdominal muscles will be visualized by ultrasound in the anterior axillary line, midway between the inferior border of the ribcage and the iliac crest. The thickening fraction will be calculated as \[(expiratory thickness - end-inspiratory thickness) / end-inspiratory thickness \]. |
| Oxygenation | The blood gas will be collected 10 minutes after application of interventional PEEP level | The PFI (PaO2/FiO2 ratio) will be calculated as arterial PaO2 (partial pressure of oxygen) divided by the FiO2 (fraction of inspired oxygen) |
| Respiratory system compliance | Measured during an inspiratory hold manoeuvre performed 10-15 minutes after the application of interventional PEEP level. | The respiratory system compliance will be calculated as the tidal volume divided by the airway driving pressure during an inspiratory hold. |
Countries
Sweden
Contacts
CONTACTHannes Widing
CONTACTPer Persson
PRINCIPAL_INVESTIGATORHannes Widing
Anesthesia and intensive care medicine, Område 5, Sahlgrenska University hospital, Västra Götalandsregionen
Outcome results
None listed