About this trial
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.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
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;
Disqualifiers
age <18 years;
pregnancy;
signs of barotrauma or documented pneumothorax;
severe tachycardia (HR > 120 bpm) and severe lacticaemia (lac > 4 mmol/L)
Trial design
Crossover
Treatments tested in this trial
Change in PEEP
Other interventionPatients 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
Treatment groups
Trial outcomes
Primary outcomes
Impact of lung collapse on cardiac output
Evaluation of the relative contribution of lung collapse (arbitrary units) on patients' cardiac output at different PEEP levels (L/min)
Impact of lung collapse on pulmonary vascular resistance
Evaluation of the relative contribution of lung collapse (arbitrary units) on pulmonary vascular resistance (dyn·s/cm\^5) at different PEEP levels
Impact of lung overdistention on cardiac output
Evaluation of the relative contribution of lung overdistention (arbitrary units) on patients' cardiac output at different PEEP levels (L/min)
Impact of lung overdistention on pulmonary vascular resistance
Evaluation of the relative contribution of lung overdistention (arbitrary units) on pulmonary vascular resistance (dyn·s/cm\^5) at different PEEP levels
Secondary outcomes
Correlation between potential for lung recruitment and PEEP-induced changes in cardiac output
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)
Correlation between potential for lung recruitment and PEEP-induced changes in pulmonary vascular resistance
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)
PEEP-induced effects on cardiac output in cardiac preload responsive vs. nonresponsive patients
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 %)
PEEP-induced effects on pulmonary vascular resistance in cardiac preload responsive vs. nonresponsive patients
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 %)
Sponsors and contacts
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