ECMO rescueJune 11, 2019
34-year-old Nagesh, a middle-class executive at a local shopping mall in Bengaluru, was suffering from fever and severe shortness of breath and was admitted to St. John’s Hospital, Bengaluru. His clinical history indicated no comorbidities or other illnesses; however, he had recently travelled to another city.
As his condition was worsening, he was diagnosed with severe community-acquired pneumonia and admitted to the intensive care unit where he was started on anti-flu medicines and placed on a mechanical ventilator to help with breathing. However, his oxygen parameters did not improve even after artificial ventilation in the prone position after sixteen hours. Doctors at St. John’s recommended extracorporeal membrane oxygenation (ECMO) support as a last, life-saving resort. ECMO is a medical device used to supply oxygen to circulating blood through an oxygenator in an effort to bypass the requirement of an injured or non-functional lung.
Unfortunately, most hospitals do not have ECMO facilities in India and St John’s hospital is no exception. The medical team at St. John’s therefore reached out to Narayana Health City, Bengaluru, for assistance. Ideally, Nagesh would be transferred to Narayana Health City before ECMO treatment. However, his condition was critical, and he was not able to be transported. In a life-saving move, the 12-member ECMO team led by Dr Harish M M, consultant and in-charge of the multi-disciplinary intensive care unit, Narayana Health City, came to St John’s with a portable ECMO unit, initiated veno-venous ECMO at St John’s, and then transferred Nagesh to Narayana Health City while on ECMO support.
At Narayana Health City, Nagesh underwent a repeat X-ray, while his previous treatment regime of Tamiflu and antibiotics was continued along with the ECMO. Because of his deteriorating condition in terms of clinical presentation with bilateral infiltration and a low response to ventilation support, he was considered to be a case of severe acute respiratory distress syndrome (ARDS). A tracheal aspirate was used for molecular testing using polymerase chain reaction to identify the causative agent for the respiratory illness. Molecular testing has the benefit of being rapid as well as having high sensitivity, and within 24 hours, he was confirmed with H1N1 infection.
ARDS is a severe form of lung injury and is defined based on the development of acute dyspnea and hypoxemia within 7 days after the insult, along with radiographic changes showing bilateral infiltrates. ARDS can be classified as mild to severe, depending on the ratio of the partial pressure of oxygen in the patient’s arterial blood (PaO2) to the fraction of oxygen in the inspired air (FiO2). If this is ratio is less than 100, the patient is classified as suffering from severe ARDS. Nagesh’s PaO2/FiO2 ratio was less than 100, classifying him as having severe ARDS.
While there is no specific therapy for ARDS, treatment should depend on the underlying condition, along with appropriate supportive care and artificial ventilation. Nagesh was continued on Tamiflu and ECMO and a broad-spectrum antibiotic to prevent bacterial infections during ventilation support.
The decision to remove ECMO support is dependent on the oxygen levels as well as the general condition of the patient. Absence of high-grade fever and infections, normal electrolytes, a normal heart rate and brain function are all factors indicating whether the patient can be weaned of the ECMO support. Though blood culture is a definitive indicator of infection, its yield is very poor especially when patients are already on antibiotics. Other indirect indicators of infection, including WBC count, body temperature, and infiltration in the lungs are monitored daily, whereas biomarkers like procalcitonin, C reactive protein etc. are monitored every 2-4 days. Once these biochemical parameters return to normal, the patient can be weaned off ECMO. Even after discharge, sequelae of ARDS, such as weight loss, fatigue, functional compromised life, myopathy etc. can often linger for months.
Nagesh had to be supported on ECMO for 12 days before his PaO2/FiO2 ratio started to stabilise and his lung function returned to normal. After discharge, he was continued on multivitamins, and followed up after 1 week. Luckily, he did not have to witness prolonged effects of ARDS and he returned to normalcy at the 1-week follow up.
According to Dr Harish, ECMO comes with a high cost, running into a few lakhs. However, the most important criteria for starting ECMO therapy is that the pathology should be reversible. It is not recommended for severe stroke or advanced cancer patients with ARDS, who may already be bedridden. Side effects of ECMO include bleeding, air embolism, low platelet counts (platelets may be destroyed in the external tubes), and hemolysis. Platelet or blood transfusions may often be required to address platelet/blood loss.
Despite the costs and side effects, ECMO must be initiated early once standard therapy (including prone ventilation) for ARDS fails, as ARDS will not respond to ECMO once the lung moves to a fibrotic phase. While few hospitals have ECMO facilities, Dr Harish advocates that patients should be referred to a suitable health care centre as early as possible and definitely no later than 2 sessions of ineffective ventilation in prone position.