An observational study in Acute Respiratory Distress Syndrome (ARDS), sponsored by University of Thessaly. Not yet recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-30.
Sponsored by University of Thessaly · Observational
The optimal timing for transition from controlled to assisted mechanical ventilation in patients with acute respiratory distress syndrome (ARDS) remains uncertain. Excessive spontaneous respiratory effort may promote injurious transpulmonary pressure swings and heterogeneous regional ventilation, whereas unnecessary prolongation of controlled ventilation may increase sedation exposure and diaphragmatic dysfunction.
This prospective, single-center physiological interventional study will enroll mechanically ventilated adults with ARDS and a PaO₂/FiO₂ ratio >100 and ≤200 mmHg, measured during PEEP=5 cmH2O, who are receiving controlled mechanical ventilation. Participants will undergo a protocolized 30-minute transition from controlled to assisted mechanical ventilation after reduction of sedation sufficient to allow spontaneous respiratory activity.
Respiratory effort and drive, airway and esophageal pressures, respiratory flow, respiratory mechanics, gas exchange, and regional ventilation measured by electrical impedance tomography will be assessed before and during the transition. Participants will subsequently be followed for 48 hours to determine whether assisted ventilation can be maintained without return to fully controlled mechanical ventilation.
Participants meeting eligibility criteria will initially remain on their clinically prescribed controlled mechanical ventilation. Sedation will be gradually reduced to permit the reappearance of spontaneous respiratory activity while avoiding clinically significant agitation or patient-ventilator dyssynchrony. Once spontaneous respiratory activity is present, participants will be transitioned to assisted mechanical ventilation. Positive end-expiratory pressure will be maintained at the pre-transition level, which will have been titrated with the use of esophageal manometry so as to achieve an end-expiratory trans-pulmonary pressure above 0 cmH2O, and inspired oxygen fraction will remain unchanged whenever clinically feasible. Inspiratory assistance will be titrated to maintain protective targets: esophageal pressure swings= 3-15 cmH2O (diaphragm protective) and transpulmonary pressure swings \< 15-20 cmH2O (lung protective).
The physiological transition trial will last 30 minutes. Continuous recordings of airway pressure, esophageal pressure, respiratory flow, and electrical impedance tomography will be obtained. Respiratory drive will additionally be assessed using airway occlusion pressure at 100 milliseconds (P0.1).
Three prespecified analysis periods will be used: T0, the final 5 minutes during controlled ventilation before transition; T1, the first 5 minutes of assisted ventilation; and T2, minutes 25-30 of assisted ventilation.
Electrical impedance tomography analyses will include regional distribution of tidal ventilation, global inhomogeneity index, end-expiratory lung impedance, ventral-to-dorsal ventilation distribution, center of ventilation, and occurrence or magnitude of pendelluft. Respiratory mechanics analyses will include esophageal pressure swing, pressure-time product of the esophageal pressure, transpulmonary pressure, respiratory system elastance, chest-wall elastance, and lung elastance.
The transition trial will be stopped if prespecified clinical intolerance or safety criteria occur. Participants who do not tolerate the trial will be returned to controlled ventilation according to clinical requirements.
After completion of the 30-minute trial, participants will be followed for 48 hours. Successful transition will be defined as maintenance of assisted mechanical ventilation without the need to return to fully controlled mechanical ventilation during this period.
1,387 studies on the registry are indexed under Respiratory Distress Syndrome; 283 are open to participants now.
This study's planned enrollment of 30 is below the median of 100 across 475 observational studies indexed under Respiratory Distress Syndrome.
Browse Respiratory Distress Syndrome studies →University of Thessaly is the lead sponsor of 195 studies on the registry; 44 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients with ARDS of severe to moderate severity (100\<PaO2/FiO2\<200 mmHg).
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Other: Protocolized Transition From Controlled to Assisted Mechanical Ventilation
Participants receiving controlled mechanical ventilation will undergo gradual reduction of sedation to permit spontaneous respiratory activity, followed by a 30-minute transition to assisted mechanical ventilation. PEEP will remain at the pre-transition value and FiO₂ will remain unchanged whenever clinically feasible. Inspiratory assistance will be titrated to maintain tidal volume at approximately 6-8 mL/kg predicted body weight. Physiological measurements will be recorded continuously, and the procedure will be terminated if prespecified intolerance or safety criteria occur.
Difference in Respiratory Mechanics between succesfull and failed transition using a pneumotachograph
The investigator will measure the respiratory mechanics at baseline, after the first five minutes of assisted ventilation and at 30 minutes of assisted ventilation. We will measure respiratory rate (breaths per minute).
Time frame: During the first thirty minutes of assisted ventilation.
Difference in Respiratory Mechanics between succesfull and failed transition using a pneumotachograph
The investigator will measure the respiratory mechanics at baseline, after the first five minutes of assisted ventilation and at 30 minutes of assisted ventilation. The measured variables will include the lung elastance, the chest wall elastance and the total respiratory system elastance (all measured in cmH₂O/L).
Time frame: During the first thirty minutes of assisted ventilation.
Difference in Respiratory Mechanics between succesfull and failed transition using a pneumotachograph
The investigator will measure the respiratory mechanics at baseline, after the first five minutes of assisted ventilation and at 30 minutes of assisted ventilation. The measured variables will include the transpulmonary pressure, which is measured in cmH₂O. During the baseline measurement both statics and dynamics measurements will be calculated, whereas during the assisted phase the investigator will include only the dynamic measurements.
Time frame: During the first thirty minutes of assisted ventilation.
Difference in Respiratory Mechanics between succesfull and failed transition using a pneumotachograph
The investigator will measure the respiratory mechanics at baseline, after the first five minutes of assisted ventilation and at 30 minutes of assisted ventilation. We will measure tidal volume (mLs).
Time frame: During the first thirty minutes of assisted ventilation.
Differences in electrical impedance tomography variables between successful and failed transition to assisted ventilation
The investigator will measure the variation in the global inhomogeneity index derived by using electrical impedance tomography.
Time frame: During the first thirty minutes of assisted ventilation.
Differences in electrical impedance tomography variables between successful and failed transition to assisted ventilation
The investigator will measure the end-expiratory lung impedance, EELI, which is measured in ohms.
Time frame: During the first 30-minutes of assisted ventilation.
Differences in electrical impedance tomography variables between successful and failed transition to assisted ventilation
The investigator will measure the ventral to dorsal ratio using the electrical impedance tomography.
Time frame: During the first 30-minutes of assisted ventilation.
Differences in electrical impedance tomography variables between successful and failed transition to assisted ventilation
The investigator will measure the variation in the pendelluft phenomenon using the impedance amplitude values.
Time frame: During the first 30-minutes of assisted ventilation.
Differences in respiratory effort between successful and failed transition to assisted ventilation
The investigator will measure the differences in esophageal pressure swings, ΔPes in cmH₂O, between the beginning of the transition phase and at the final 5 minutes of the 30-minute trial.
Time frame: During the first 30-minutes of assisted ventilation.
Differences in respiratory effort between successful and failed transition to assisted ventilation.
The investigator will measure the differences in the esophageal pressure-time product measured in cmH₂O⋅s/min, between the beginning of the transition phase and at the final 5 minutes of the 30-minute trial.
Time frame: During the first 30-minutes of assisted ventilation.
No study locations are listed for this record.
Plan to share: No
No publications or documents are linked to this record.
Start is estimated for Oct 2026; primary completion for Oct 2028, 24 months later.
Of 225 non-industry observational studies under Respiratory Distress Syndrome, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 47. This study's planned 24 months is close to that.
Counting every sponsor, half of 231 studies reached it within 24 months; a quarter within 12 and three quarters within 49.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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