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.
Procedure: Lateral Position (left and right lateral decubitus)
Prior to initiating the protocol, patients will be sedated deeply with sedatives and opioids and paralyzed. Patients will be evaluated in 5 positions sequentially: 1) Supine 2) Left lateral 3) Supine 4) Right lateral 5) Supine. The side with the least ventilation evaluated by EIT will define which side will start the sequence. Each step will last 30 minutes. Aeration measured by Electric Impedance Tomography (EIT) and lung ultrasound, distribution of the lung ventilation and perfusion measured by EIT, ventilator and hemodynamic parameters, esophageal pressure, and blood gas analysis will be recorded at the end of each step. Continuous monitoring of blood pressure, heart rate and saturation of arterial blood (SpO2) will be carried out during all steps of the protocol to assess the tolerance to the procedure.
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.
Hospital Rebagliati
Jesús María, Lima, Peru
Rollin Roldán, MD, Principal Investigator
Hospital Nacional Edgardo Rebagliati Martins