Researchers at the Jerusalem College of Technology and the Shaare Zedek Medical Center in Israel have announced a method of measuring systolic blood pressure that may be more accurate than current techniques, according to findings presented at the Cardiovascular Aging: New Frontiers and Old Friends conference in Colorado. Approximately one-third of Americans have elevated blood pressure, but some of the automatic devices that are currently used are prone to errors that may lead to unnecessary prescription of antihypertensive medications, according to the study authors. Blood pressure is usually assessed via a manual (auscultatory) or automatic (oscillometry) meter in an office or hospital setting. However, these measurements can be affected by “white coat syndrome,” which is when a patient’s fear or anxiety in a medical setting causes an elevation in blood pressure. At-home automatic measurements are typically used to avoid the white coat effect, but oscillometry-based meters sometimes offer a low level of accuracy. “The automatic oscillometric technique is less accurate than the manual auscultatory technique when both are used in the clinician’s office,” said Meir Nitzan, PhD, the study’s first author. The new device uses a technique called photoplethysmography to more accurately measure systolic blood pressure. A pressure cuff is wrapped around the patient’s arm, and an electro-optic probe is placed on the finger. “The finger probe is similar to that of a pulse oximeter,” Dr. Nitzan said. “It includes a light-source that emits light into the finger and a detector that measures the light transmitted through the finger. The transmitted light exhibits pulses at the heart rate, due to cardiac-induced blood volume changes in the finger tissue. When the cuff pressure increases to above systolic blood pressure, then these pulses disappear. When the cuff pressure decreases to below systolic blood pressure, they reappear. This effect enables the determination of systolic blood pressure.” Currently available automatic blood pressure measurement devices are commonly off by 10 to 15 mm Hg. This is mainly due to indirect determination of the blood pressure from the oscillometric air-pressure wave measurements taken by automatic devices. Unnecessary prescription of antihypertensives may lead to hypotension, especially in the elderly population. Patients may be at risk of dizziness, fainting, acute kidney injury, or cognitive impairment. Source
