Post Cardiac Arrest Syndrome: a review of therapeutic strategies

Stub D, Bernard S, Duffy SJ, Kaye DM.

Circulation. 2011 Apr 5; 123(13):1428-35

 

By Felipe Teran, MD

 

Article capsule

The significant morbidity and mortality associated with patients who survive to an Out-of-Hospital Cardiac Arrest (OHCA) has driven the attention to the syndrome occurring immediately after return of spontaneous circulation (ROSC). The understanding of the physiopathology of this syndrome has allowed the development of problem-based therapeutic interventions. Systems organization, respiratory, circulatory and neuroprotective therapeutic strategies, together with the prompt treatment of underlying coronary disease have been studied extensively. Among all, therapeutic hypothermia (TH) accumulates the strongest and most practice changing evidence improving survival and good neurological outcome in survivors of OHCA.

Take- home messages

  • Development of regional systems of care to provide specialized, multidisciplinary management of the Post Cardiac Arrest Syndrome seems reasonable and could improve outcomes in OHCA patients.
  • Arterial hyperoxia has been found to be an independent factor of increased mortality. Oxygenation and ventilation should be directed to avoid both hypoxia and hyperoxia.
  • Early hemodynamic stabilization should be attempted using fluid therapy and vasoactive drugs as first step.
  • Optimal hemodynamic targets remain unclear but in light of the limited existing evidence, it is reasonable to aim a mean arterial pressure of 65 to 100 mmHg.
  • Mechanical support, such as aortic balloon pump and extracorporeal membrane oxygenation (ECMO) should be considered, particularly in the setting of Acute Coronary Syndrome (ACS) complicated with cardiogenic shock and severe left ventricular dysfunction. However, of these therapies, only ECMO has shown to improve survival.
  • Approximately two thirds of the deaths during the post cardiac arrest period are explained by the anoxic brain injury.  This effect appears to be effectively palliated by the early initiation of therapeutic hypothermia (TH) with a number needed to treat (NNT) of 6.
  • Two major, multicenter, randomized– controlled trials have shown a significant improvement in both survival and good neurological recovery with TH in patients in whom the initial cardiac rhythm is ventricular fibrillation (VF) or Ventricular Tachycardia (VT). It is still unclear whether this effect would apply to asystole and pulseless electric activity (PEA).
  • There are not definitive evidence-based recommendations regarding the method to use and the duration of TH.
  • In light of several observation studies showing the efficacy of early percutaneous coronary intervention (PCI) in patients with STEMI after OHCA, urgent interventional approach for all STEMI with OHCA patients is currently recommended.
  • It is still unclear whether patients with OHCA but no evidence of STEMI should or not have urgent PCI following return to ROSC, but in light of the available evidence, current guidelines suggest that it is reasonable to consider PCI in all survivors of OHCA in whom there is suspicion of cardiac origin.
  • A number of non-randomized, observational trials have shown that the combination of TH and PCI is safe, feasible and could lead to better survival.
  • Absent pupillary and corneal reflexes at day 3 and the absence of somatosensory evoked potentials to test the integrity of central pathways have both shown to be reliable predictors of poor outcomes; however no factors have been found to be sufficiently reliable to conclude that continued care is futile in a patient recovered from OHCA.
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