During stage III anesthesia, which species has a tachycardia threshold of greater than 160 bpm?

During stage III anesthesia, which species has a tachycardia threshold of greater than 160 bpm?

• A. Large Dog
• B. Small Dog
• C. Cat
• D. Horse

Answer: (B)

Tachycardia during stage III anesthesia reflects the heart’s response to light anesthesia, pain, or other stress, and the point at which we call it tachycardia varies by species and size because their normal autonomic and metabolic responses differ. Small dogs have a relatively high heart rate tolerance under anesthesia due to their higher metabolic rate, so a heart rate must rise quite a bit before it’s considered tachycardia. In this species, the tachycardia threshold is greater than about 160 beats per minute, making them the choice where tachycardia occurs only at higher HR. Other species tend to show tachycardia at lower absolute heart rates under anesthesia, or have different baseline ranges and responses, so their thresholds are not above 160 bpm in the same way.

Tachycardia during stage III anesthesia reflects the heart’s response to light anesthesia, pain, or other stress, and the point at which we call it tachycardia varies by species and size because their normal autonomic and metabolic responses differ. Small dogs have a relatively high heart rate tolerance under anesthesia due to their higher metabolic rate, so a heart rate must rise quite a bit before it’s considered tachycardia. In this species, the tachycardia threshold is greater than about 160 beats per minute, making them the choice where tachycardia occurs only at higher HR.

Other species tend to show tachycardia at lower absolute heart rates under anesthesia, or have different baseline ranges and responses, so their thresholds are not above 160 bpm in the same way.