What happens to finger pulse amplitude and estimated systolic pressure when the arm is held above the head?

What happens to finger pulse amplitude and estimated systolic pressure when the arm is held above the head?

• A. Pulse amplitude increases and systolic pressure rises
• B. Pulse amplitude decreases dramatically and systolic pressure becomes much lower than at heart level
• C. Pulse amplitude remains unchanged and systolic pressure remains the same
• D. Pulse amplitude fluctuates with no predictable pattern

Answer: (B)

When a limb is held above the heart, the hydrostatic column of blood lowers the pressure at the measurement site. The pressure wave that reaches the finger is generated by the heart, but gravity subtracts a portion of that pressure as the blood travels upward. Because of this, the pulse at the finger becomes weaker and the systolic reading estimated from that finger pressure drops compared with the heart level. In practical terms, raising the arm above the head reduces arterial pressure at the finger by a sizable amount (roughly a few mmHg per centimeter of height), so the pulse amplitude decreases dramatically and the estimated systolic pressure is much lower than at heart level. This predictable pattern contrasts with options that suggest the pulse would be stronger, unchanged, or fluctuate without pattern.

When a limb is held above the heart, the hydrostatic column of blood lowers the pressure at the measurement site. The pressure wave that reaches the finger is generated by the heart, but gravity subtracts a portion of that pressure as the blood travels upward. Because of this, the pulse at the finger becomes weaker and the systolic reading estimated from that finger pressure drops compared with the heart level. In practical terms, raising the arm above the head reduces arterial pressure at the finger by a sizable amount (roughly a few mmHg per centimeter of height), so the pulse amplitude decreases dramatically and the estimated systolic pressure is much lower than at heart level. This predictable pattern contrasts with options that suggest the pulse would be stronger, unchanged, or fluctuate without pattern.