The purpose of this study is to evaluate if a postural recruitment maneuver (PRM) improves the aeration and distribution of lung ventilation in patients with Acute Respiratory Distress Syndrome (ARDS) caused by COVID-19 infection; without the need to reach high airway pressures as in the standard lung recruitment maneuver and / or place the patient in prone position. This strategy could be particularly useful in the context of a major health emergency in centers with limited resources.

The PRM is based on the known effect of gravity on transpulmonary pressure (PL). Two principles explain its mechanism of action: 1) the first indicates that atelectasis and poorly ventilated areas of the lung can improve their aeration by putting the lung in the highest position. Opposite lateral decubitus causes that upper lung to have a higher PL and allow a recruiting effect at moderate airway pressures. 2) The second principle is based on Laplace's Law and postulates that once the upper lung is recruited, it remains without lung collapse if a sufficient level of positive end-expiratory pressure (PEEP) is applied. Based on these two precepts, PRM consists of sequentially moving the patient from the supine to the left lateral decubitus to recover the aeration of the right lung. After that, the patient is placed in the right lateral position to recruit the left lung; keeping the right lung without collapse by continuous use of PEEP. Finally, the patient returns to the supine position looking for an improvement in the distribution of ventilation and global pulmonary aeration, with a subsequent improvement in gas exchange and pulmonary mechanics.

Inclusion Criteria:

• Patients > 18 years of age
• Patients with moderate-to-severe ARDS as per the Berlin definition
• Infection due to COVID-19
• Body mass index (BMI) ≤ 35 kg /m^2.

Exclusion Criteria:

• Contraindication for EIT monitoring

  1. Unstable spine or pelvic fractures
  2. Pacemaker, automatic implantable cardioverter defibrillator
  3. Skin lesions between the 4th and 5th ribs where the EIT belt is worn

• Pregnancy

• Major hemodynamic instability::

  1. Mean arterial pressure lower than 60 mm Hg despite adequate fluid resuscitation and use of vasopressors.
  2. FC> 120 or <60 per minute
  3. Presence of uncontrolled arrhythmias.

• More than 1 week of mechanical ventilation

• Failure of more than 2 extrapulmonary organs.

This physiological study will enroll 12 adult ARDS patients admitted to the COVID Intensive Care Unit of Rebagliati Hospital. Informed consent will be obtained from the patient or legally authorized substitute decision maker.