Which of the following provides a measure of an animal's pulse rate?

• A. Ventilator
• B. Capillary refill time
• C. Pulse oximeter
• D. Flow meter

Answer: (C)

Pulse rate is read from the rhythmic changes in arterial blood volume with each heartbeat. A pulse oximeter does this by shining light into tissue and detecting how the absorbed light changes with the pulsing blood flow. That pulsatile signal is converted into heart rate, which the device displays (along with oxygen saturation).

The ventilator is for supporting or controlling breathing, not measuring heart rate. Capillary refill time assesses how quickly blood returns to the capillaries after blanching and reflects perfusion status, not heart rate. A flow meter measures the rate of gas or liquid flow, which is unrelated to how often the heart is beating.