Emergency Medical Technician (EMT) Intermediate Practice Exam

What is the approximate cardiac output of a person with a heart rate of 70 beats/min and a stroke volume of 75 mL?

1. 3 L/min

2. 5 L/min

3. 7.5 L/min

4. 10 L/min

The correct answer is: 5 L/min

To calculate the cardiac output, you use the formula: Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV). In this scenario, the heart rate is 70 beats per minute, and the stroke volume is 75 mL. First, convert the stroke volume from mL to liters, since cardiac output is typically expressed in liters per minute. Since 1 liter equals 1000 mL, a stroke volume of 75 mL is equivalent to 0.075 liters. Now, applying the numbers to the formula gives: CO = HR × SV CO = 70 beats/min × 0.075 L/beat CO = 5.25 L/min. While 5.25 L/min is slightly higher than 5 L/min, it is generally rounded to 5 L/min when approximating in typical clinical settings. Thus, the cardiac output of a person with those specific heart rate and stroke volume values is approximately 5 L/min, confirming that this is the most reasonable choice among the available options. Several other figures, like 3 L/min, 7.5 L/min, and 10 L/min, are outside the expected range for a resting adult's cardiac