Which side effect of ketamine is characterized by increased heart rate?

The side effect characterized by increased heart rate is tachycardia. Ketamine is known to exert various physiological effects, one of which is its ability to stimulate the sympathetic nervous system. This stimulation can lead to an increase in heart rate as the body prepares for heightened levels of activity or response, commonly referred to as the "fight or flight" response.

Tachycardia is a specific term that denotes a faster than normal heart rate, typically defined as a resting heart rate exceeding 100 beats per minute. In the context of ketamine administration, particularly at anesthetic doses, tachycardia can occur due to its cardiovascular effects.

While emergency delirium is related to altered states of consciousness and perception, and drooling is a side effect that may occur with other medications or situations but does not relate to heart rate changes, hypertension refers to elevated blood pressure rather than heart rate. Therefore, understanding that tachycardia specifically describes an increase in heart rate, makes it the correct identification of the side effect in this scenario.