Gas Exchange Derangement Physiopathology in Critically Ill Patients With COVID-19

Gas Exchange Derangement Physiopathology and Response to Different Levels of Positive End-expiratory Pressure in Critically Ill Patients With COVID-19

The study was designed to understand the pathophysiology of gas exchange derangement in critically ill patients with COVID-19. Specifically we will evaluate the effect of 3 different levels of positive end-expiratory pressure (PEEP) and two different levels of inspiratory oxygen fraction (FiO2) on gas exchange by analyzing shunt and dead space. Furthermore, complete respiratory mechanics and distribution of ventilation and perfusion by electrical impedance tomography will be assessed at each level of PEEP.

Inclusion Criteria:

• Patients admitted in intensive care unit for COVID-19 related Acute Respiratory Distress Syndrome (ARDS) requiring invasive mechanical ventilation

Exclusion Criteria:

• Pregnancy
• Hemodynamic instability (80-90 mmHg increase or 30-40 mmHg decrease systolic arterial pressure compared to baseline value or need of vasopressors to maintain systolic blood pressure higher than 85 mmHg or electrocardiogram evidence of ischemia/arrhythmias)
• Presence of pneumothorax and/or pneumomediastinum
• Contraindications to Electrical Impedance Tomography (pacemaker, implantable cardioverter defibrillator, thoracic drainages)