Which of the following is NOT part of Cushing's triad?

Cushing's triad is a clinical syndrome characterized by specific signs that indicate increased intracranial pressure. It includes a combination of bradycardia, irregular respirations, and a widened pulse pressure.

Widened pulse pressure occurs when there is a significant difference between systolic and diastolic blood pressure, often as a compensatory response to increased intracranial pressure. Bradycardia, which is a slower than normal heart rate, occurs as a result of increased pressure on the brain, affecting the autonomic nervous system. Irregular respirations indicate that the brainstem is affected, where the respiratory centers are located, due to elevated intracranial pressure.

In contrast, an increased heart rate does not form part of Cushing's triad. Typically, the body's response to increased intracranial pressure would be bradycardia, as opposed to tachycardia (increased heart rate), which might occur in different circumstances but is not associated with this specific syndrome. Thus, the selection of increased heart rate as the answer reflects the understanding that it does not align with the classical presentation of Cushing's triad.