From the Research
Post cardiac arrest, the expected labs to be drawn include arterial blood gases, complete blood count, comprehensive metabolic panel, cardiac enzymes, coagulation studies, lactate levels, toxicology screen, and blood cultures, as these tests help identify the cause of the arrest, assess end-organ damage, guide resuscitation efforts, and inform prognosis. The selection of these labs is based on the need to evaluate oxygenation, ventilation, and acid-base status, as well as to assess for anemia, infection, or bleeding, and to check electrolytes, kidney and liver function 1. Additionally, cardiac enzymes such as troponin and CK-MB are essential to evaluate for myocardial injury, while coagulation studies like PT/INR and PTT help assess clotting function 2. Lactate levels are crucial to evaluate tissue perfusion and severity of shock, and a toxicology screen is necessary if overdose is suspected 3. Blood cultures are also important if infection is a concern, and additional tests like brain natriuretic peptide (BNP) for heart failure assessment, thyroid function tests, and ammonia levels if metabolic causes are suspected may be considered 4, 5. It is critical to draw these labs immediately post-resuscitation and at regular intervals to monitor response to treatment and detect complications. Some studies suggest that point-of-care testing can be useful in the pre-hospital setting to rapidly detect pathological acid-base imbalances and potassium concentrations, which can inform specific interventions on scene and potentially improve survival 1. However, the utility of certain tests like cardiac troponin in the post-cardiac arrest setting has been questioned, with some studies suggesting it may not perform well as a diagnostic test for ischemic aetiology or predictor of left ventricular systolic dysfunction and survival 2. Overall, the choice of labs should be guided by the individual patient's clinical presentation and the need to identify reversible causes of cardiac arrest.