A 42-year-old female is admitted to the ICU after a motor vehicle accident. She develops ARDS secondary to lung contusions and is initiated on VV ECMO. The clinical course is complicated by worsening acute kidney injury. The latest laboratory workup reveals acidosis with a pH of 7.18 and hyperkalemia of 6.5 mEq/L. Sodium bicarbonate, calcium gluconate, and insulin-dextrose are administered. Although adding on a continuous renal replacement therapy circuit to the ECMO circuit, the patient develops a short run of ventricular tachycardia, which quickly degenerates into asystole.
What is the immediate next step in managing this patient?
A. Initiate chest compressionsCorrect Answer: A
VV ECMO provides pulmonary support with little cardiac support. The patient on VV ECMO is completely dependent on his native cardiac function to maintain cardiac output and hemodynamics. Any decrease in cardiac or hemodynamic function in such patients should be supported in the same way as a patient who is not on ECMO. Therefore, in the event of a cardiac arrest, it is prudent to follow the advanced cardiac life support algorithm and initiate CPR (A). In this patient it would mean initiating high-quality chest compressions (B), as well as administering intravenous epinephrine. Because asystole is not a shockable rhythm, defibrillation is unlikely to help in this case (D).
During a cardiac arrest, there is no cardiac output, and this impairs the flows through VV ECMO. But with high-quality chest compressions, it is possible to run the pump at low flows, which may be adequate to maintain oxygenation. The FiO2 on the ventilator can be turned up to 1.0 as a safety precaution to protect against hypoxia in the event of inadequate pump flows. Institution of VA ECMO is recommended in case of refractory cardiac arrest when there is a strong suspicion for a reversible cause of cardiac arrest. The survival rates and neurological outcomes after ECPR are influenced by the time to initiation of VA ECMO after cardiac arrest. It seems reasonable to consider ECPR after 10 minutes of high-quality conventional CPR in a patient with a potentially reversible cause of cardiac arrest. In this patient on VV ECMO, conversion to VA ECMO by arterial cannulation should be considered if initial CPR fails to achieve return of spontaneous circulation (C).
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