Steroid Treatment as Anti-inflammatory and Neuroprotective Agent Following Out-of-Hospital Cardiac Arrest. A Randomized Trial

BACKGROUND:

Each year approximately 5400 individuals suffer from Out-of-Hospital Cardiac Arrest (OHCA) in Denmark and despite an improved prognosis 30-day mortality is around 90%. For OHCA patients resuscitated successfully and admitted to an Intensive Care Unit (ICU) the 30-day mortality remains higher than 50% due to a complicated systemic response, referred to as the Post Cardiac Arrest Syndrome (PCAS). PCAS consists of four interacting components: 1) ischemic/reperfusion brain injury, 2) myocardial dysfunction, 3) a systemic inflammatory response and 4) persistent stress from the triggering cause of the cardiac arrest, e.g. acute myocardial infarction. PCAS progresses during the first 1-2 days following resuscitated cardiac arrest, and the treatment aims to reduce neurologic injury by cooling the patient to 33-36° C, circulatory support with vasopressors, inotropics or mechanical devices as well as identification and treatment of reversible causes to the cardiac arrest, e.g. acute revascularization of an AMI.

Several studies have shown that the systemic inflammatory response is associated with a high risk of poor outcome following OHCA. Inflammatory markers associated with poor outcome include interleukin (IL) 6, high sensitivity C-reactive protein (hsCRP), leucocytes, IL-1b, IL-10, IL-13, tumor necrosis factor alpha (TNF-alpha) and procalcitonin. Despite of this, there is no specific treatment that addresses this complicated and life-threatening systemic response, and guidelines remain inconclusive in this field.

Anoxic irreversible brain injury remains the leading cause of death following resuscitated OHCA. The complex mechanism is one of the components in the PCAS and is thought to develop due to neuron apoptosis and reperfusion/ischemic injury. Further, the biomarker neuron-specific enolase (NSE) is correlated to neuron damage in the blood stream and has a strong predictive value for poor outcome following OHCA. Inhibiting the causes of the systemic inflammatory response and thereby potentially the brain injury in the very early stages following resuscitation from OHCA may therefore be key to optimizing post-cardiac arrest care.

Following resuscitated OHCA, the function of the adrenal gland is compromised due to global ischemia and reduced levels of the hormone steroid, glucocorticoid, are produced. Glucocorticoid has an important role in several physiologic processes including an anti-inflammatory systemic response. As a result, resuscitated cardiac arrest patients are affected by a severe inflammatory response, while the natural defense mechanism of the body to modulate inflammation is suppressed. Systemic treatment with steroids serves as an anti-inflammatory mediator and counteracts acute microcirculation injury and free radical formation, resulting in diminished vasodilation and reduction of edema, e.g. brain edema. Two small studies have shown signs of improved survival and neurologic outcome among patients who was given injections with glucocorticoids after in-hospital cardiac arrest. The incidence of adverse events was not higher in patients receiving glucocorticoids. Long-term treatment with glucocorticoids is associated with a series of side effects, whereas short-term treatment only has a few side effects. Systemic treatment with glucocorticoids could therefore be an important and safe factor in the treatment of resuscitated cardiac arrest patients that could potentially improve survival and neurological outcome.