Which of the following is NOT a component of Cushing's triad?

Cushing's triad is a clinical syndrome characterized by three classic signs that are indicative of increased intracranial pressure. These signs include hypertension, bradycardia, and irregular respirations.

Hypertension occurs as a compensatory response to maintain cerebral perfusion when intracranial pressure rises. Bradycardia results from increased pressure exerting effects on the brainstem, which regulates heart rate. Irregular respirations are also associated with disturbances in brainstem function due to the increased pressure within the skull.

Tachycardia, on the other hand, is not a component of Cushing's triad. In fact, it typically occurs in situations of shock or acute stress and is opposite to what one would expect to see in the context of increased intracranial pressure, where bradycardia predominates. This makes it distinct and vital for recognizing the signs of Cushing's triad correctly, allowing for appropriate assessment and intervention in a patient with suspected elevated intracranial pressure.