What is the primary tool used to recognize critical clinical changes in complex casualties during prolonged field care?

The primary tool used to recognize critical clinical changes in complex casualties during prolonged field care is the TCCC Card. This card is specifically designed for Tactical Combat Casualty Care and serves as a quick reference tool for medics in the field. It helps to track vital signs, treatments provided, and any changes in the patient’s condition.

This comprehensive data aids medics in making informed decisions regarding further medical interventions, monitoring the casualty's status, and communicating effectively with other medical personnel. The TCCC Card is crucial in high-stress environments where expedient and accurate assessments of a patient's condition can significantly influence outcomes.

While the other options present valuable information or records, they do not serve as the primary recognition tool for immediate clinical changes in the same way that the TCCC Card does. The Patient Health Record may contain comprehensive medical history but is not used on the battlefield for real-time updates. The Prolonged Casualty Care flow chart is helpful for implementing protocols but is less focused on critical recognition. An Incident Report documents an event, but it is not used for monitoring clinical changes in patients.