Discussion on ECMO

By: Ryan Cutro, Erin Sventy, Kelvin Opoku, Afnan Al-Raimi

CASE:

Janet is a nine-year-old girl who has been in excellent health. She is on the girls’ soccer team at her school, is an excellent student and also excels at playing the piano. While playing with her friends in her backyard, she received a small scratch from a rusty nail. She did not inform her parents as she thought it was something minor. Forty-eight hours later, she developed tenderness around the area and noticed that it was a bit red and swollen. She showed it to her Mom who took her to the doctor. The scratch was cleaned and an antiseptic salve was applied. Janet’s pediatrician also prescribed a ten-day course of antibiotics for her. Twenty-four hours later, Janet developed a fever and complained of shortness of breath. She looked pale and her parents rushed her to the emergency room of the local hospital. Her vital signs on arrival to the ED were as follows:

• BP: 80/45
• HR: 135
• RR: 36
• Temperature (oral): 102.3^oF
• SpO2: 92% on room air

 Within 30 minutes of her arrival to the ED, Janet suffered cardiopulmonary arrest. She was successfully resuscitated, but her condition was tenuous. She did not respond to conventional management of septic shock 12 hours after initiation of therapy. Consequently, the medical team was considering ECMO.

 Do you think ECMO should be offered to Janet? Why, or why not.

DISCUSSION:    

Extracorporeal membrane oxygenation (ECMO), extracorporeal life support, or extracorporeal lung assist is an invasive procedure in which a patient’s blood is routed from the venous system, mechanically pumped through an artificial lung, and pumped back into the pulmonary system of the body.  The artificial lung can fully saturate the blood’s hemoglobin with oxygen, exchange heat, and remove carbon dioxide¹.  There are two types of ECMO; venoarterial (VA) and venovenous (VV). Both provide respiratory support, but only VA ECMO provides cardiac support. Mechanical cardiopulmonary support is most often applied intraoperatively to facilitate cardiac surgery but can also be delivered in a more prolonged fashion in an intensive care unit.  In this instance, the major goal is to support the perfusion of organs in patients with ARDS and/or cardiac dysfunction to give time to evaluate and resolve the underlying disease processes¹.  The Extracorporeal Life Support Organization (ELSO) has set criteria for the initiation of ECMO.  It includes those patients with acute severe cardiac or pulmonary failure that is potentially reversible and unresponsive to conventional management. They go on to give situations in which ECMO should be started:

• Hypercapnic respiratory failure with an arterial pH less than 7.20
• Refractory cardiogenic shock
• Cardiac arrest
• Failure to wean from cardiopulmonary bypass after cardiac surgery
• As a bridge to either cardiac transplantation or placement of a ventricular assist device
• PaO₂/FiO₂ <100 mmHg despite optimization of the ventilator settings, including the tidal volume, positive end-expiratory pressure (PEEP), and inspiratory to expiratory (I:E) ratio²

While the premise of using ECMO for ARDS and shock is sound, there is much debate whether it has better outcomes than conventional ventilation.  A multicenter randomized controlled trial was done by Peek et al to determine the efficacy of ECMO compared to conventional ventilator support in severe respiratory failure.  The study randomly assigned 180 adults to receive continued conventional management or treatment by ECMO.  They included patients with a pH< 7.20 and potentially reversible respiratory failure while also utilizing certain exclusion criteria.  Of the patients chosen for ECMO, 63% survived to 6 months compared to 47% by conventional management.  The study concluded that the transfer of eligible patients to ECMO facilities will improve survival.³   Another study by Brechot et al was a single center, cross-sectional survey that evaluated the use of ECMO in refractory cardiovascular dysfunction due to severe septic shock.  They evaluated cardiovascular dysfunction as having a low ejection fraction, low cardiac index, low P/F ratios, pH< 7.2 and hypotension on high dose catecholamines.  They found that more than 70% of the patients were rescued and concluded that ECMO is a valuable therapeutic option.⁴

There are many benefits to employing ECMO, however, there are some inherent complications that should be considered.  30%-40% of patients may experience life-threatening bleeding due to the necessary continuous heparin infusion and platelet dysfunction.   The continuous heparin infusion is used to prevent thromboembolism complications from clots that can form within the ECMO circuit and pumped into the systemic circulation.  With the use of high dose heparin also comes the risk of the patient developing heparin-induced thrombocytopenia (HIT).⁵

Additionally, there are financial factors that should also be evaluated before ECMO is chosen.  The financial burden of an intensive care unit stay can be devastating to a patient and family. However, there is growing evidence that using ECMO in certain situations is more cost effective than conventional management. Peek et al designed a study for analysis of ECMO cost-effectiveness.  They gathered data about patients’ transport and days in hospital at different levels of care while using techniques and methods to estimate lifetime incremental costs.  The study concluded that the use of ECMO is likely to be more cost effective and efficient than conventional management.³

Finally, there are ethical dilemmas that are inherent in the initiation and withdrawal of ECMO.  While ECMO has been referred to as a bridge to recovery there is concern about using ECMO as a “bridge to nowhere.”  One question that should be discussed is “To whom should ECMO be offered?”  Abrams et al suggest that institutions that have ECMO capability should have strict criteria for initiating and withholding ECMO.  Another question, “What should be done with a patient on ECMO when there is no expectation for recovery?”  Abrams et al presented their views regarding this decision in their discussion of two cases.  They suggest that a patient with sound mental capacity and judgment should first be given an opportunity to understand their medical circumstances and the anticipated outcomes. If the patient chooses not to have ECMO withdrawn, the decision should be respected.  In patients who lack the capacity to acknowledge the decision, the patients’ decision maker should be consulted and robust communication with the physicians should lead to an optimal decision.⁶

DECISION:

First and foremost, the decision to recommend Janet for ECMO is one that should be based on the communication between her parents and the physicians.  They will need to discuss the gravity of the situation and be prepared to make very difficult decisions for the removal of ECMO should Janet’s condition deteriorate.  Assuming the patient’s ABG shows pH< 7.20, ventilator settings have been optimized, fluid bolus and IV pressors have been utilized, and IV antibiotics have all not helped to improve her status, ECOM should be initiated.

 

References:

1. Walsh BK, Green M. Extracorporeal Membrane Oxygenation. In: Neonatal and Pediatric Respiratory Care, 4th edition Elsevier; 2015:353-368.

2. ELSO guidelines for ECMO centers (updated May 2015) http://www.elso.med.umich.edu/guide.htm (Accessed on March 1, 2015).

3. Peek GJ, Mugford M, Tiruvoipati R, Wilson A, Allen E, Thalanany MM, et al. Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial. The Lancet;374(9698):1351-1363.

4. Brechot. “Venoarterial Extracorporeal Membrane Oxygenation Support for Refractory Cardiovascular Dysfunction During Severe Bacterial Septic Shock*.” Critical care medicine 41.7 (2013):1616-1626. Web.

5. Zangrillo, Alberto, et al. “A meta-analysis of complications and mortality of extracorporeal membrane oxygenation.” Critical care and resuscitation 15.3 (2013):172-178. Web.

6. Abrams DC, Prager K, Blinderman CD, Burkart KM, Brodie D. Ethical Dilemmas Encountered With the Use of Extracorporeal Membrane Oxygenation in Adults. Chest 2014;145(4):876-882.