Effect of Different Ventilatory Strategies on Cardiac Function in Patients With Acute Respiratory Failure

Study Overview
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Brief Summary
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Mechanical ventilation with low tidal volume (about 6 ml.kg-1) reduces mortality in ALI/ARDS patients respect to high tidal volume ventilation (about 12 ml.kg-1). This finding is usually explained by alveolar tidal overdistension associated to high tidal volume. Stretch-induced lung injury may trigger a cytokine-mediated inflammatory response. This may contribute to the development of systemic inflammatory response and multiple system organ failure and death. High tidal volume strategies might affect organ function by pathways not mediated by inflammatory response. It is well recognized the inverse relationship between tidal volume and cardiac output during mechanical ventilation. Nevertheless there are no clinical studies about cardiac output changes induced by low (6 ml.kg-1) and high tidal volume (12 ml.kg-1) in ALI/ARDS patients. The study hypothesis is that high tidal volume ventilation reduces cardiac output in ALI/ARDS patients respect to low tidal volume strategy. Thereafter reduced hemodynamic impact could explain beneficial effect of low respect to high tidal volume ventilation. If study hypothesis is confirmed, other studies should define the main cause of mortality reduction related to low tidal volume strategies and if appropriate hemodynamic monitoring and support should be required when low tidal volume strategies are harmful (i.e. traumatic brain injury).

Official Title
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Hemodynamic Impact of Low and High Tidal Volume Mechanical Ventilation in Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS) Patients

Conditions
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Respiratory Distress Syndrome

Intervention / Treatment
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* Procedure: Mechanical ventilation with low and high tidal volume


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: diagnosis of ARDS/ALI Exclusion Criteria: mean arterial pressure lower than 65 mmHg beginning or change of vasoactive agents infusion rate in the last 2 hours

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Two different tidal volumes (6 and 12 ml.kg-1 of ideal weight) are alternatively delivered to patients 30 minutes each one. The order of the two tidal volumes is randomized. Between the two study tidal volumes, patient returns for 30 minutes to the tidal volume used before the study recruitment. | Procedure: Mechanical ventilation with low and high tidal volume<br>* Tidal volume of 6 or 12 ml.kg-1, calculated on ideal body weight<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cardiac index |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| oxygen delivery |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 
| oxygen consumption |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 
| mixed venous saturation |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 
| relationship between partitioned elastance (lung and chest wall) and cardiac index difference between ventilation with tidal volume 6 and 12 ml.kg-1 |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 
| abdominal perfusion pressure (mean arterial pressure minus abdominal pressure) |  | after 30 minutes of mechanical ventilation with tidal volume of 6 or 12 ml.kg-1 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Respiratory Distress Syndrome, Adult, Tidal volume, cardiac output, Respiration, Artificial, Protective ventilation