What is a critical action if a casualty is unresponsive?

In situations where a casualty is unresponsive, checking for a pulse is critical because it helps to assess the individual's heart function and determine whether they are experiencing cardiac arrest. If there is no pulse, immediate interventions like CPR should be initiated. This step is crucial because it guides subsequent actions—if a pulse is absent, high-quality chest compressions are essential to maintain blood circulation until emergency medical services can intervene.

Other options may seem reasonable in certain contexts but do not serve the immediate purpose of assessing the urgency of the situation effectively. For instance, starting CPR might be necessary, but checking the pulse first allows for a more informed decision on whether CPR needs to begin. Checking blood pressure is not typically performed in emergency settings as an initial step because it does not provide the quick assessment needed in an unresponsive patient scenario. Attempting to wake the individual by shaking them does not address the critical medical needs of the patient and could waste valuable time in a situation where every moment counts. Checking for a pulse helps to prioritize the necessary lifesaving actions based on the patient's condition.