Noninvasive BP: Oscillometry
Basic, Basic Sciences
Non-invasive blood pressure measurement involves inflating the cuff greater than the systolic blood pressure and then slowly decreasing the pressure until oscillations are detected. The time that oscillations are first detected corresponds to the systolic pressure. These oscillations will gradually increase until reaching a peak at mean arterial pressure and then begin to fade until disappearing at diastolic pressure. Of note, most electronic/automated devices measure oscillations to detect the mean pressure and then utilize proprietary algorithms to calculate systolic and diastolic pressures.
For proper fit, the cuff width should be approximately half the arm circumference. Additionally, the thigh, calf, or forearm may also be utilized if the upper arm is not available based on surgical site or other co-morbidities.