Using the metatarsal pulse in a 'Poor Man's Doppler', an 'Absent' result indicates BP is less than how many mmHg?

Using the metatarsal pulse in a 'Poor Man's Doppler', an 'Absent' result indicates BP is less than how many mmHg?

• A. 40 mmHg
• B. 60 mmHg
• C. 80 mmHg
• D. 100 mmHg

Answer: (B)

In this technique, there’s a practical lower limit to what a crude Doppler can detect in a peripheral artery. When you use a metatarsal site with a “Poor Man’s Doppler,” if no pulse signal is heard, it means the systolic pressure at that site is below the device’s detection threshold. That threshold for peripheral, small-vessel flow is about 60 mmHg, so an absent signal indicates the systolic BP is likely under 60 mmHg. We’re talking about an approximate value, since exact detectability can vary with the device, site, temperature, and vasomotor tone.

In this technique, there’s a practical lower limit to what a crude Doppler can detect in a peripheral artery. When you use a metatarsal site with a “Poor Man’s Doppler,” if no pulse signal is heard, it means the systolic pressure at that site is below the device’s detection threshold. That threshold for peripheral, small-vessel flow is about 60 mmHg, so an absent signal indicates the systolic BP is likely under 60 mmHg. We’re talking about an approximate value, since exact detectability can vary with the device, site, temperature, and vasomotor tone.