In my second quarter of year two med school we are covering the cardiac system (2nd time since last year, but in more depth). We learned how to take a blood pressure last year and did some extensive practicing fall quarter this year, but we’re back at it again for the cardiac system. One step of the blood pressure taking technique we are taught is after applying the cuff we are to take the patient’s wrist and check for their pulse. We are to continue checking the pulse as we inflate the cuff so we know when the cuff is at the point where it is blocking the flow of blood. Inflate the cuff another 20 mmHg of pressure then listen with the stethoscope on the brachial artery as the cuff slowly deflates. We are listening for the blood as it begins to flow again as the cuff is deflating.
What was surprising to me was that most clinicians that have taken my BP have not checked the pulse while inflating the cuff. Talking with my peers and instructors we found we’ve shared this experience. I’ve watched a clinician taking my BP pick a random number on the BP dial and inflate to that number. Here’s where the problem can come in: if there’s an auscultatory gap. An auscultatory gap is the temporary disappearance of the blood flow sounds while the cuff is deflating.
It is most often seen in older patients and it is strongly associated with hardening of the arteries. The problem with not checking the pulse while inflating the cuff is that the patient’s blood pressure could be grossly underestimated if the reading is unintentionally begun in the gap. Checking the pulse ensures that the top, and true, systolic pressure is reached before beginning the reading.
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Cavallini, M. C., Roman, M. J., Blank, S. G., Pini, R., Pickering, T. G., & Devereux, R. B. (1996). Association of the auscultatory gap with vascular disease in hypertensive patients. Annals of Internal Medicine, 124(10), 877–883.