What is an essential first step when evaluating an unconscious patient?

In the evaluation of an unconscious patient, the essential first step is to assess breathing. This is critical because, without effective breathing, oxygen supply to the body is compromised, which can lead to significant organ damage or death in a short time. By checking for the presence or absence of breathing, healthcare providers can quickly determine the urgency of the situation and the need for immediate interventions such as CPR or rescue breaths.

While opening the airway is also important and often performed in conjunction with assessing breathing, it is the act of checking whether the patient is breathing that directly informs the necessary next steps. Identifying if the patient has adequate ventilation allows responders to prioritize their actions based on the severity of the situation.

The other options, such as checking circulation and calling emergency services, are critical as well, but they typically follow the assessment of the patient's breathing status. This structured approach ensures that the most immediate threats to life are addressed first, aligning with the principles of basic life support and emergency care protocols.