ECMO: What is the Intensivist’s Role?
A 52-year-old man with a history significant for hypertension presented to the emergency department (ED) with cough, dyspnea, fever and myalgias. On examination, the temperature was 38.2 °C, blood pressure 143/64, heart rate 109 beats per minute, respiratory rate 33 breaths per minute and the oxygen saturation 78% while breathing room air. He was placed on high-flow nasal cannula and encouraged to self-prone with initial improvement in his oxygen saturation. However, three hours later, his work of breathing increased with progressive hypoxemia requiring intubation, mechanical ventilation and admission to the intensive care unit. Nucleic acid testing for SARS-CoV-2 RNA returned positive. During the next 24 hours, he developed refractory hypoxemia with P/F of 56 mm Hg despite low tidal volume ventilation, paralysis with rocuronium infusion, inhaled epoprostenol and prone positioning. Hemodynamics remained acceptable without vasoactive medication. He developed non-oliguric acute kidney injury, but did not require renal replacement therapy. Is this patient a candidate for ECMO and, if so, who should guide initiation and management?
The Society of Critical Care Medicine (SCCM) and Extracorporeal Life Support Organization (ELSO) recently published a position paper on the role of the intensivist in the initiation and management of ECMO. The multidisciplinary task force comprised of intensivists, acute care surgeons and emergency medicine physicians performed a retrospective review of the literature and made 23 graded recommendations for ECMO support regarding patient selection, management, mitigation of complications, coordination of multidisciplinary care and communication with surrogate decision-makers.
The task force recommended that initiation of ECMO should involve a multidisciplinary team led by the intensivist. When possible, the task force advised that patients with respiratory failure should receive optimal mechanical ventilation and prone positioning prior to consideration for ECMO. Indications for respiratory ECMO for patients with reversible ARDS include P/F < 50 mm Hg for greater than 3 hours or P/F < 80 mm Hg for greater than 6 hours despite FiO2 > 80% and PEEP > 10 cm H20. Alternatively, ECMO can be considered for respiratory acidosis with arterial pH < 7.25 and PaCO2 > 60 mm Hg for greater than 6 hours while aiming for plateau pressure < 32 cm H20 and respiratory rate 35 breaths per minute or below. Regarding relative contraindications for ECMO, the authors supported the ELSO guidelines that identify end-stage malignancy, unrecoverable CNS damage and poor overall prognosis from prolonged mechanical ventilation as factors that should guide the decision to withhold ECMO. Multidisciplinary ECMO teams should be aware of factors affecting ECMO survival and recognize that hospital mortality for critically ill patients receiving ECMO support is 40% for respiratory ECMO, 60% for cardiac ECMO and 70% for ECPR.
The position paper stated that many specialists can effectively and safely perform cannulation for ECMO, including cardiothoracic surgeons, general surgeons, vascular surgeons, interventional cardiologists, interventional radiologists, emergency medicine physicians and intensivists. Cannulation performed by intensivists should utilize the percutaneous approach, rather than an open technique. The decision to utilize a dual-lumen versus single-lumen cannula should take into consideration the patient’s habitus as well as potential for recirculation. To minimize complications, the authors recommended development of institutional protocols for cannulation, including the use of adjunctive ultrasound, echocardiography, radiography or fluoroscopy to guide wire and cannula placement. The intensivist must understand how to manage common complications of ECMO. As such, the intensivist must play a vital role in both monitoring for bleeding and assessing the severity to decide whether to reduce or hold anticoagulation. The task force acknowledged that there are no consensus recommendations for the optimal anticoagulant or monitoring. Targets for anticoagulation can include activated clotting time (ACT), partial thromboplastin time (PTT), anti-Xa levels and thromboelastogram. The decision to perform procedures on patients supported by ECMO must weigh the risks of bleeding versus thrombosis and mechanical failure of the circuit, if anticoagulation is held. Mechanical thrombosis of the VV ECMO circuit can lead to sudden and life-threatening hypoxemia, thus the ECMO team must have a plan for swift deployment of back-up circuit components.
Daily rounding and management of ECMO patients should involve collaboration between the primary critical care and multidisciplinary ECMO teams. Family-centered communication should be established between the care teams and the patient’s surrogate decision-maker with clear communication about prognosis and maintenance of support. Case review should occur regularly for quality improvement. Although not pertinent to our patient, the position paper also included recommendations regarding initiation and management of VA ECMO for patients with cardiogenic shock and refractory cardiac arrest as well as VV ECMO for respiratory support as a bridge to lung transplant.
Returning to our patient with COVID-19 pneumonia, the primary intensivist consulted the multidisciplinary ECMO team that included team members from multiple specialties, including cardiothoracic surgery, critical care medicine, emergency medicine, cardiology, acute care surgery and perfusion. The decision was made to initiate VV ECMO for refractory hypoxemia with P/F < 80 for several hours due to severe ARDS induced by SARS-CoV-2 infection. Two-site percutaneous cannulation of the right internal jugular and femoral veins was performed by an intensivist on the ECMO team with real-time transesophageal echocardiography guidance and oversight by cardiothoracic surgery. Prior to cannulation, the patient was bolused with heparin and subsequently maintained on a heparin infusion targeting anti-Xa levels. Daily management was coordinated between the primary critical care team and the multidisciplinary ECMO team. His course was complicated by an episode of massive hemoptysis requiring therapeutic bronchoscopy. The decision was made to hold heparin until definitive hemostasis was achieved. He later required percutaneous thoracostomy for a large pleural effusion for which heparin was again held peri-procedure. Ultimately, his pulmonary compliance improved as evidenced by increasing tidal volume on ultra-protective pressure control ventilation. He was successfully decannulated by the intensivist on day 16 of venovenous ECMO support and was later weaned from mechanical ventilation.
ECMO is a complex therapy that should be reserved for patients with severe respiratory or cardiac failure refractory to conventional supportive critical care. Delivery of mechanical circulatory support should be led by a multidisciplinary critical care team that includes ECMO specialists with various training backgrounds in surgery, critical care, emergency medicine, cardiology and perfusion. In collaboration with a multidisciplinary team, intensivists trained in ECMO physiology, patient selection, cannulation, anticoagulation and management of complications can effectively guide the initiation and management of ECMO.
Della Volpe J, et al. Joint Society of Critical Care Medicine-Extracorporeal Life Support Organization Task Force Position Paper on the Role of the Intensivist in the Initiation and Management of Extracorporeal Membrane Oxygenation. Critical Care Medicine 2020;48(6):838-845.