Patients are cared for on the scene based on:

In emergency medical situations, the primary focus is on the signs and symptoms presented by the patient. This approach is crucial because these indicators provide immediate, actionable information about the patient's condition and needs. Signs refer to measurable or observable factors, such as vital signs, physical injuries, or external manifestations of a medical issue, while symptoms are the experiences reported by the patient, such as pain, dizziness, or nausea.

By assessing these signs and symptoms, responders can prioritize care based on the severity of the situation and determine the most appropriate interventions. Scenarios can vary greatly, and the underlying diagnosis may not always be clear at the scene, making reliance on the observable signs and reported symptoms essential for making timely medical decisions.

In contrast, mechanisms of injury provide context for the situation but do not always directly inform specific patient care. While bystander information can be valuable, it is often subjective and can sometimes lead to misinterpretation. Consequently, treating patients based on their direct signs and symptoms allows for more effective and accurate emergency management.