**4. Patient selection for ECPR**

ECPR is a final effort employed in a patient with a deep circulatory shock after CA that is refractory to all standard treatments, and no further intervention will assuredly lead to the patient's demise. ECMO is brought in this scenario to assist with shock state while dithering to elucidate the cause of CA and later allows reversal if possible [41]. The American heart association guidelines advised that ECPR should be instituted in a patient if ECMO is rapidly available and deployable within a facility, patient has a brief duration from collapse, and the underlying condition is reversible [42]. As ECPR is a complex technique that requires an experienced and well-trained paramedic team, careful precision, teamwork, and coordinated efforts of a lot of persons to institute ECMO with ongoing, patients with CA should be carefully selected who can potentially benefit from ECPR [43].

In patient with OHCA, prognostic factors associated with better survival and neurological outcome are patient age <70 years, shorter duration of low flow, a sustained shockable rhythm, effective CPR with a target end-tidal carbon dioxide (EtCO2) > 10 mmHg during resuscitation, lower lactate level, higher pH, and lower SOFA score [44]. While these all criteria increase the likelihood of a favorable outcome, there are no universal selection criteria. Although there are no clearly defined indications, most


*VT = ventricular tachycardia, VF = ventricular fibrillation, ROSC = return of spontaneous circulation, DNR/DNI = do not resuscitate or intubate, CA = cardiac arrest, ETCO2 = end tidal carbon dioxide.*

#### **Table 2.**

*Positive and negative predictors of ECPR.*

centers perform ECPR for young patients with an initial shockable rhythm or presumed correctable cause and those with a witnessed collapse and bystander CPR without ROSC within 10–20 minutes of CCPR. In patients with IHCA, ECPR is useful in patients with CA in the cardiac surgical ICU, medical cardiac ICU, cardiac catheterization laboratory, and CA before or after cardiac surgery or intervention. When a cardiac diagnosis is irreversible pathology, cardiac replacement therapy, such as heart transplantation or artificial heart, should be considered [45, 46]. Poor prognostic factors after ECPR are patients with poor physical activity levels such as those confined to bed; severe permanent neurologic injury; noncardiopulmonary cause of arrest, such as severe sepsis; prolonged CCPR without ROSC; inadequate ACLS, such as failed advanced airway or ineffective chest compression due to severe hypovolemia or unfavorable chest wall anatomy (e.g., aortic rupture or severe pectus excavatum); and pre-existing severe multiple organ failure. However, no single one can be considered an absolute contraindication for ECPR; the physician in charge of a patient's care should discuss resuscitation with leaders of the CPR and ECLS teams if the situation arises. Prognostic factors can be broken down into positive/negative factors influencing outcomes explained in **Table 2** [46].
