Cardiac Arrest

Basics

ALERT
  • 2020 American Heart Association Advanced Cardiac Life Support (ACLS) proposed a number of changes
  • Routine administration of calcium for treatment of cardiac arrest is NOT recommended
  • Indications for emergent coronary angiography:
    • ST-segment–elevation myocardial infarction (STEMI)
    • Shock
    • Electrical instability
    • Signs of significant myocardial damage
    • Ongoing ischemia
  • Deliberate strategy for temperature control, regardless of arrest location or presenting rhythm in adults who do not follow commands after return of spontaneous circulation (ROSC)

Description

  • Cardiac arrest is characterized by acute:
    • Unresponsiveness
    • Pulselessness
    • Little to no respiratory effort
  • Pathophysiology:
    • Cessation of cardiac output halts oxygen and nutrient delivery, leading to ATP depletion, ionic imbalances, and immediate neuronal damage caused by cytotoxic edema
    • Return of spontaneous circulation introduces oxidative stress, excitotoxicity from calcium influx, and microvascular dysfunction
    • Ischemia-reperfusion triggers the activation of the innate immune system, with microglial activation, leukocyte infiltration, and cytokine release resulting in blood–brain barrier disruption and further neuronal injury
    • Global ischemia and reperfusion cause microvascular collapse, thrombi formation, and dysregulated cerebral autoregulation, leading to periods of inadequate perfusion or hyperperfusion
    • Persistent hypoxia and mitochondrial failure drive delayed neuronal cell death (apoptosis, pyroptosis), accompanied by systemic inflammatory responses resembling sepsis, which can worsen neurologic outcomes
  • Factors affecting survival:
    • Initial rhythm
    • Total “no flow” and “low-flow” (CPR) time
    • Time to high-quality CPR
    • Time to successful defibrillation (as indicated)
    • Time to basic life-support interventions

Etiology

Potentially reversible causes of cardiac arrest (“5 Hs and Ts”):

  • Hypovolemia
  • Hypoxia
  • Hydrogen ion (acidosis)
  • Hypo/hyperkalemia
  • Hypothermia
  • Toxins, including:
    • Calcium channel blockers, β-blockers, digoxin
    • Tricyclic antidepressants
    • Opiates, cocaine
  • Tamponade, cardiac
  • Tension pneumothorax
  • Thrombosis (pulmonary, coronary)
  • Trauma

Pediatric Considerations

  • Sudden cardiac arrest in children is often of a respiratory rather than cardiac etiology
  • Follow current ACLS guidelines for pediatric cardiac arrest. Major differences between adult and pediatric cardiac arrest management include:
    • Depth of compressions for pediatric populations should be >1/3 anteroposterior diameter of chest
    • For two-rescuer CPR, a 15:2 compression to ventilation rate is recommended
    • Infants should receive CPR using the two-thumb-encircling-hands technique
    • Drug dosage differences: See “Medications”

Pregnancy Considerations

Follow current ACLS guidelines for management of a pregnant cardiac arrest patient:

  • Be aware that airway may be difficult
  • Compressions should be performed at a higher location than conventional CPR, slightly above the center of the sternum
  • Follow Adult ACLS guidelines for defibrillation
  • Pre- or postcardiac arrest pregnant patients should be placed in the left lateral recumbent position; during arrest, perform manual left uterine displacement to relieve aortocaval compression
  • To ensure a best possible outcome for the fetus, all efforts must be geared toward maternal survival
  • Concomitantly prepare for a perimortem cesarean section:
    • Assuming no maternal ROSC, this procedure should be considered at 5 min after arrest to optimize maternal and fetal outcomes

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