Finding an LVAD MAP: What the Books Don’t Tell You

When auscultating for noninvasive blood pressure, it is common to place the stethoscope chestpiece over the brachial artery, inflate the cuff, and then listen for the Korotkoff sounds. This is fine as the stethoscope chestpiece is large enough and the sounds are loud enough that the chestpiece just has to be in the general area of the brachial artery. 

HOWEVER, obtaining a doppler “MAP” for a patient with an LVAD is a different procedure altogether and must be approached differently. LVAD patients typically do not have a palpable or audible pulse, so instead the cuff is inflated to complete compression, and the pressure at which the first doppler signal is detected is considered the “MAP.” (It is really the systolic blood pressure–sort of–but this is the convention because you won’t lose doppler signal as the cuff is deflated; no diastolic pressure can be measured.) The doppler pen must be directly over the artery to catch the signal, so you can’t listen blindly. You must FIRST find the signal, THEN inflate the cuff, eliminating the signal, and THEN slowly deflate the cuff and record the pressure at which the signal returns. 

Sound silly? Not as silly as not detecting a systolic blood pressure of 160 peripherally. It is important to observe how your team is gathering this vital sign.