An interventional study of Low positive end-expiratory pressure and Medium positive end-expiratory pressure in Respiratory Failure, ARDS (Acute Respiratory Distress Syndrome) and Pneumonia, sponsored by Vastra Gotaland Region. Recruiting at 2 sites in Sweden. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-02.
Sponsored by Vastra Gotaland Region · Not applicable, Interventional, and Supportive care
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.
1,650 studies on the registry are indexed under Respiratory Insufficiency; 296 are open to participants now.
This study's planned enrollment of 25 is below the median of 55 across 1,043 interventional studies indexed under Respiratory Insufficiency.
Browse Respiratory Insufficiency studies →Vastra Gotaland Region is the lead sponsor of 267 studies on the registry; 107 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Discontinuation criteria during ongoing study intervention:
Low positive end-expiratory pressure (4 cmH2O)
Procedure: Low positive end-expiratory pressure
Medium positive end-expiratory pressure (10 cmH2O)
Procedure: Medium positive end-expiratory pressure
High positive end-expiratory pressure (16 cmH2O)
Procedure: High 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.
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.
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.
Inspiratory effort
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.
Time frame: Measured during 5 uninterrupted breaths 10 minutes after application of interventional PEEP level
Inspiratory drive
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.
Time frame: Measured during 5 uninterrupted breaths 10 minutes after application of interventional PEEP level
Effort-to-drive ratio
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).
Time frame: Calculated from the measures collected 10 minutes after application of interventional PEEP level
Neuromechanical efficiency
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).
Time frame: Calculated from the measures collected during the occlusion manoeuvre performed 10-15 minutes after application of interventional PEEP level
Thickening fraction of the diaphragm (TFdi)
Measured by ultrasound at the right hemidiaphragm. The thickening fraction of the diaphragm (TFdi) will be calculated as \[ (end-inspiratory diaphragm thickness - end-expiratory diaphragm thickness) / end-expiratory diaphragm thickness) \].
Time frame: Measured 10 minutes after application of interventional PEEP level
Transpulmonary driving pressure
Change in transpulmonary pressure ( airway pressure - esophageal pressure) from end-expiration to end-inspiration will be calculated using ventilator data and high-resolution manometry
Time frame: Measured during 5 breaths 10 minutes after application of interventional PEEP level
Occlusion pressure
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.
Time frame: The occlusion pressure will be measured during an occlusion manoeuvre performed 10-15 minutes after application of interventional PEEP level.
Airway driving pressure
Difference in airway pressure between end-expiration and during an inspiratory hold will be calculated from the ventilator data.
Time frame: Measured during an inspiratory hold performed 10-15 minutes after application of interventional PEEP level
Lung compliance
Lung compliance will be calculated as the tidal volume divided by the change in transpulmonary pressure from end-expiration to end-inspiration.
Time frame: Measured during an inspiratory hold performed 10 - 15 minutes after application of interventional PEEP level
Thickening fraction of the expiratory abdominal muscles (TFabd)
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 \[(expiratory thickness - end-inspiratory thickness) / end-inspiratory thickness \].
Time frame: Measured 10 minutes after application of interventional PEEP level
Oxygenation
The PFI (PaO2/FiO2 ratio) will be calculated as arterial PaO2 (partial pressure of oxygen) divided by the FiO2 (fraction of inspired oxygen)
Time frame: The blood gas will be collected 10 minutes after application of interventional PEEP level
Respiratory system compliance
The respiratory system compliance will be calculated as the tidal volume divided by the airway driving pressure during an inspiratory hold.
Time frame: Measured during an inspiratory hold manoeuvre performed 10-15 minutes after the application of interventional PEEP level.
Central venous oxygen saturation (ScvO2)
Oxygen saturation of venous blood drawn from a central venous catheter.
Time frame: Venous blood gas will be collected 10 minutes after application of interventional PEEP level
Tidal volume
The volume change from end-expiration to end-inspiration. Will be acquired from the ventilator.
Time frame: Measured in 5 breaths 10 minutes after the application of interventional PEEP level.
Respiratory rate
The number of breaths per minutes (respiratory rate) will be calculated from the volume-time curve acquired from the ventilator.
Time frame: Measured 10 minutes after the application of interventional PEEP level.
Dead space
Dead space (volume of gas not participating in gas exchange) will be calculated from the difference between arterial and end-expiratory partial pressure of Carbon dioxide, using blood gas analysis and capnography.
Time frame: The dead space will be calculated 10 minuted after application of interventional PEEP level.
Change in end-expiratory lung volume
The change in end-expiratory lung volume will be calculated as the accumulated difference in inspired and expired gas volume during the first 15 breaths after a PEEP change. This will be acquired using the ventilator.
Time frame: Measured in the 15 breaths following a PEEP change.
End-expiratory diaphragm thickness
The end-expiratory diaphragm thickness will be measured by ultrasound as the thickness of the diaphragm at the right hemisphere at end-expiration.
Time frame: This will be measured during end-expiration 10 minutes after the application of interventional PEEP level.
Neuroventilatory efficiency
The neuroventilatory efficiency will be calculated as the tidal volume divided by the change from end-expiratory to inspiratory electric activity of the diaphragm (Eadi). The tidal volume will be calculated using data from the ventilator and Eadi acquired using a NAVA (neurally adjusted ventilatory assist) catheter.
Time frame: Measured from 5 breaths 10 minutes after the application of interventional PEEP level.
Neuromuscular efficiency
The neuromuscular efficiency will be calculated as the change in transdiaphragmatic pressure (esophageal pressure - gastric pressure) from end-expiration to inspiration divided by the change in electric activity of the diaphragm from end-expiration to inspiration.
Time frame: This will be calculated from 5 breaths acquired 10 minutes after the application of interventional PEEP level.
Electric activity of the diaphragm
Electric activity of the diaphragm (Eadi) during end-expiration, inspiration and occlusion manoeuvres will be measured by NAVA (neurally adjusted ventilator assist) catheters in Voltages
Time frame: Measured during 5 breaths 10 minutes after application of interventional PEEP level. Additionally measured during an occlusion manoeuvre 10-15 minutes after application of interventional PEEP level.
Thickening fraction of the intercostal muscles
Intercostal muscles will be examined by ultrasound in the cranio-caudal direction at the second intercostal space. The thickening fraction of the intercostal muscles (TFic) will be calculated as the \[ (end-inspiratory intercostal thickness - end-expiratory intercostal thickness) / end-expiratory intercostal thickness) \].
Time frame: Measured 10 minutes after application of interventional PEEP level
Plan to share: No — The acquired swedish ethical permit does not allow for the sharing of data to international researcher without a confidentiality review or the application of a new ethical permit
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Vastra Gotaland Region