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NCT Number: NCT07423520

HemodynamIc eFfects of Lung Collapse and overdIstension During ARDS

The management ARDS relies on ventilatory strategies aimed at limiting ventilator-induced lung injury (VILI). The setting of PEEP is still subject of debate, as randomized clinical trials comparing standardized higher versus lower PEEP strategies failed to demonstrate a clear survival advantage. Only few studies explored the hemodynamic effects of various PEEP levels depending on lung recruitability. Furthermore, the role of PEEP-mediated lung collapse and overdistention on patients' hemodynamics has yet to be elucidated. In this physiologic study, the association between EIT-measured lung collapse and overdistention and cardiac function will be explored, accounting for the individual potential for lung recruitment, partitioned respiratory mechanics and cardiac preload responsiveness. Three PEEP levels will be tested in a randomized, crossover fashion: PEEP corresponding to the crossing point between lung collapse and overdistention, PEEP associated with low lung collapse, PEEP associated with low lung overdistention.

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Key information

Conditions

ARDS AHRF Consciousness Disorders Lung Diseases Nervous System Diseases Neurobehavioral Manifestations Neurologic Manifestations Pathological Conditions, Signs and Symptoms Respiration Disorders Respiratory Distress Syndrome Respiratory Tract Diseases Signs and Symptoms Unconsciousness

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Fondazione Policlinico Universitario A.Gemelli IRCCS

Rome, 00168, Italy

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • acute respiratory failure with onset < 1 week from a predisposing risk factor, such as pneumonia, non-pulmonary infection, trauma, transfusion, aspiration, or shock;
  • bilateral opacities on chest radiography and computed tomography or bilateral B lines and/or consolidations on lung ultrasound not fully explained by effusions, atelectasis, or nodules/masses;
  • pulmonary edema not exclusively or primarily attributable to cardiogenic pulmonary edema/fluid overload, and hypoxemia/gas exchange abnormalities not primarily attributable to atelectasis;
  • PaO2/FiO2 ratio ≤ 200 during invasive controlled mechanical ventilation;

Exclusion criteria

  • age <18 years;
  • pregnancy;
  • signs of barotrauma or documented pneumothorax;
  • severe tachycardia (HR > 120 bpm) and severe lacticaemia (lac > 4 mmol/L)
  • pre-existing decompensated heart failure (NYHA class 3-4 and/or documented left ventricular ejection fraction < 35%);
  • contraindications to EIT placing (open chest wounds, presence of cardiac pacemaker);
  • intubation as a result of an acute exacerbation of chronic pulmonary disease;
  • contraindications to esophageal balloon placement (high bleeding risk, esophageal varices).

Treatment and study plan

Change in PEEP

Other

Patients will undergo a decremental PEEP trial to determine the crossing-point PEEP. Secondly, three PEEP levels (low collapse PEEP, low overdistention PEEP and crossing point between lung collapse and overdistention PEEP) will be compared in a randomized order with 30-minute steps

Primary outcomes

  1. Impact of lung collapse on cardiac output

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    Evaluation of the relative contribution of lung collapse (arbitrary units) on patients' cardiac output at different PEEP levels (L/min)

  2. Impact of lung collapse on pulmonary vascular resistance

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    Evaluation of the relative contribution of lung collapse (arbitrary units) on pulmonary vascular resistance (dyn·s/cm^5) at different PEEP levels

  3. Impact of lung overdistention on cardiac output

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    Evaluation of the relative contribution of lung overdistention (arbitrary units) on patients' cardiac output at different PEEP levels (L/min)

  4. Impact of lung overdistention on pulmonary vascular resistance

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    Evaluation of the relative contribution of lung overdistention (arbitrary units) on pulmonary vascular resistance (dyn·s/cm^5) at different PEEP levels

Secondary outcomes

  1. Correlation between potential for lung recruitment and PEEP-induced changes in cardiac output

    Time frame: Assessment at the end of each of the three 30 minute steps

    The effects of PEEP on cardiac output (mL/min) will be correlated through Pearson correlations with the individual potential for lung recruitment, as determined by the recruitment-to-inflation ratio (R/I)

  2. Correlation between potential for lung recruitment and PEEP-induced changes in pulmonary vascular resistance

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    The effects of PEEP on pulmonary vascular resistance (dyn·s/cm^5) will be correlated through Pearson correlations with the individual potential for lung recruitment, as determined by the recruitment-to-inflation ratio (R/I)

  3. PEEP-induced effects on cardiac output in cardiac preload responsive vs. nonresponsive patients

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    The effects of PEEP on cardiac output (L/min) will be compared through subgroup comparisons (student t-test) in patients who are preload responsive and patients who are not (preload responsiveness assessed through pulse-pressure variation, expressed in %)

  4. PEEP-induced effects on pulmonary vascular resistance in cardiac preload responsive vs. nonresponsive patients

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    The effects of PEEP on pulmonary vascular resistance (dyn·s/cm^5) will be compared through subgroup comparisons (student t-test) in patients who are preload responsive and patients who are not (preload resposnsiveness assessed through pulse-pressure variation, expressed in %)

  5. Relationship between transpulmonary pressures and central venous pressure variations

    Time frame: At the end of each of the three 30 minute steps

    The relationship between transpulmonary pressure variations (cmH2O) and central venous pressure variations (cmH2O) between PEEP levels will be assessed through Pearson correlations

  6. Lung hysteresis

    Time frame: At the end of each of the three 30 minute steps

    Lung hysteresis will be assessed at each of the tested PEEP levels and expressed as the area of the pressure-volume loop of the respiratory system obtained with a low-flow inflation/deflation maneuver from PEEP to a pressure of 30 cmH2O, in mL*cmH2O

  7. Lung aeration distribution

    Time frame: At the end of each of the three 30 minute steps

    Lung aeration distribution at each PEEP level tested will be assessed with electrical impedance tomography (EIT) and expressed as dorsal fraction of ventilation (% of total tidal volume)

  8. Relationship between PEEP-induced changes in lung volume and PEEP-induced changes in pulmonary vascular resistance

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    The effects of PEEP on pulmonary vascular resistance (dyn·s/cm^5) will be correlated through Pearson correlations with the individual PEEP-induced changes in lung volume (mL)

  9. Relationship between PEEP-induced changes in lung volume and PEEP-induced changes in cardiac output

    Time frame: Assesment performed at the end of each of the three 30 minute steps

    The effects of PEEP cardiac output (L/min) will be correlated through Pearson correlations with the individual PEEP-induced changes in lung volume (mL)

Interested in participating?

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Sponsors and collaborators

Lead sponsor

Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Other

Registry information

Official study title

HemodynamIc eFfects of Lung Collapse and overdIstension in Patients With Moderate-to-seVEre Acute Respiratory Distress Syndrome: the HI-FIVE Physiologic Study

Acronym: HI-FIVE

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Feb 20, 2026
Registry last updated
Feb 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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