A nurse must perform which diagnostic test for a patient with chest pain in the emergency department?

The electrocardiogram (ECG or EKG) is the most critical and immediate diagnostic test for a patient experiencing chest pain in the emergency department. This test is essential for assessing the heart's electrical activity and can provide crucial information about potential myocardial ischemia or infarction. The ECG helps to identify any abnormal heart rhythms, signs of ischemia, or other cardiac conditions that may be causing the chest pain. Prompt interpretation of the ECG can guide immediate treatment decisions, such as the need for further cardiac intervention or medication.

In contrast, while a chest X-ray can help evaluate for other causes of chest pain, such as pulmonary issues, it does not provide direct information about cardiac function. An echocardiogram, which uses ultrasound to visualize the heart, is more comprehensive but is not typically the first line of investigation in acute scenarios where immediate assessment of electrical activity is needed. A complete blood count (CBC) might be useful in some contexts, but it does not directly assess cardiac issues and therefore is not prioritized in acute chest pain evaluations.