Extracorporeal membrane oxygenation (ECMO) for severe COVID & critically ill Patients

by Dr. Chetan Rao Vaddepally | Aug 23, 2021 | Pulmonology

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The pneumonia presented with the novel coronavirus disease 2019 can lead to severe respiratory failure with profound hypoxemia that requires endotracheal intubation and mechanical ventilation. Patients who do not respond to optimal conventional mechanical ventilation can become candidates for management with Extracorporeal Membrane Oxygenation (ECMO) in multi speciality centres with appropriate resources i.e. equipment and hospital personnel.

What does ECMO support do?

ECMO support is given by temporarily drawing blood from the patient’s body to allow artificial oxygenation of red blood cells. Carbon dioxide is also removed with the help of the heart and lung machine for ECMO. It is used in select patients with cardiac or respiratory failure to support the body when the lungs or heart are unable to do so. Though the mortality benefit from ECMO ranges from 50 to 70% in adults there is no data that gives clarity on ECMO in Covid-19 ARDS patients (Acute Respiratory Distress Syndrome).

ECMO Indications

Patients needing respiratory support only.
Patients with severe symptoms who need both cardiac and respiratory support
ECMO may even be indicated while CPR (cardiopulmonary resuscitation) is being carried out.

Types of ECMO

Venovenous (VV) ECMO: Blood is removed from the venous system i.e. the network of veins and a part of the circulation that works to deliver deoxygenated blood to the heart, passed through an oxygenator, and then returned back to the venous system where it passes through the lungs. VV ECMO is an option in Covid for eligible adults with ARDS.
Venoarterial (VA) ECMO: Blood is removed from the venous system and returned to the arterial system, so as to ensure both cardiac and pulmonary support. The use of Venoarterial ECMO is reserved for select Covid patients with severe respiratory failure, severe heart failure and some other heart related complications.

Sedation for COVID-19 patients may require more sedation than some other critically ill patients since higher sedation requirements in COVID-19 patients may be due to their young age, higher respiratory drive, increased clearance caused by other medications they might be on, and a particularly intense inflammatory response.

Patient support by ECMO

Often Tracheostomy is considered after the initiation of ECMO in Non-COVID-19 patients who have respiratory failure in order to improve patient comfort and allow the lightening of the sedation given by the physician. As in all patients supported with ECMO, adequate continuous anticoagulation is required to maintain ECMO circulation. Providing adequate ECMO circuit anticoagulation while avoiding bleeding or thrombosis can be a challenging balancing act.

ECMO support for ARDS patients

Patients with other types of ARDS (Acute respiratory distress syndrome) may have a median duration of ECMO for perhaps ten days or so, with a total length of stay in the ICU ward of a multi-speciality facility for approximately one month. However, early data for COVID-19 patients indicate that considerably longer duration of ECMO support would be needed for critical patients, with a median duration of 29 days in one study, and with other studies reporting use of ECMO for almost 3 to 6 weeks.

Cannula insertion for ECMO may include complications such as neurologic injury (from hypoxemia or thrombosis), bleeding, thrombocytopenia (i.e. heparin-induced or others), and also cannula-related vascular complications. Long-term complications occur in survivors of severe Covid related acute respiratory distress syndrome (ARDS) and ECMO. The most common is the poor health-related quality of life, perhaps due to physical limitations, psychiatric symptoms such as anxiety, depression, post-traumatic stress disorder, and chronic pain.