If an arterial line transducer is placed 20 cm below the level of the heart, how much higher will the measured arterial pressure be compared with the true arterial pressure?

If an arterial line transducer is placed 20 cm below the level of the heart, how much higher will the measured arterial pressure be compared with the true arterial pressure?

• A. 7.5 mmHg
• B. 10 mmHg
• C. 15 mmHg
• D. 20 mmHg

Answer: (C)

Hydrostatic pressure from the vertical height of the blood column affects arterial line readings. A transducer placed below the heart by 20 cm experiences the weight of that blood column, adding pressure to the heart pressure. In clinical terms, about 0.75 mmHg is added per centimeter of blood, so 20 cm yields roughly 15 mmHg. Therefore the measured arterial pressure will be higher by about 15 mmHg compared with the true arterial pressure at the heart.

Hydrostatic pressure from the vertical height of the blood column affects arterial line readings. A transducer placed below the heart by 20 cm experiences the weight of that blood column, adding pressure to the heart pressure. In clinical terms, about 0.75 mmHg is added per centimeter of blood, so 20 cm yields roughly 15 mmHg. Therefore the measured arterial pressure will be higher by about 15 mmHg compared with the true arterial pressure at the heart.