Vital Signs in Isolated Head Injury and Intracranial Pressure

Explanation:

The set of vital signs most compatible with a diagnosis of isolated head injury with increasing intracranial pressure is: BP 170/100, pulse 50/min. This condition is known as Cushing's triad and is characterized by increased systolic blood pressure, widened pulse pressure, and a decreased heart rate.

These signs indicate that the body is trying to maintain cerebral perfusion in the face of rising intracranial pressure. Hypertension with a systolic pressure elevation and bradycardia (slow heart rate) are physiologic responses to increased intracranial pressure. When combined with respiratory depression, they comprise Cushing's triad, which is a late sign of rising intracranial pressure and impending brain herniation.

This reflects the body's attempt to restore and maintain cerebral blood flow by increasing arterial pressure to overcome the increased intracranial pressure. The widened pulse pressure (difference between systolic and diastolic pressures) also contributes to the effort to ensure adequate cerebral perfusion.