Blood Pressure Discrepancy Between Arm and Finger as a Predictor of Intradialytic Hypotension: A Pilot Study

To early detect intradialytic hypotension, we used continuous finger-cuff blood pressure technology in our hemodialysis patients. We noticed differences between noninvasive blood pressure measurements at the brachial and finger sites. Such discrepancies might reveal arterial property changes from proximal to distal arm. We then investigated if blood pressure discrepancies helped predict intradialytic hypotension for each hemodialysis session.

For our outpatient hemodialysis patients, we applied a continuous noninvasive finger-cuff blood pressure monitor at the beginning of each hemodialysis, and measured the brachial blood pressure at 15-min intervals. The blood pressure discrepancy is calculated as finger minus brachial blood pressure. Intradialytic hypotension is defined as an absolute nadir systolic blood pressure of 100 mmHg for baseline systolic blood pressure > 160 mmHg or a nadir of 90 mmHg otherwise. The vital signs and discrepancy trend evolution were analyzed with locally weighted scatterplot smoothing regression analysis.

In 42 hemodialysis sessions of 15 enrolled patients, there were 11 hypotensive episodes. For these hypotensive episodes, a smaller predialytic blood pressure discrepancy with a lower brachial diastolic and pulse pressure was noted. Combining these three vital sign measurements, a simple formula of [SBParm + DBParm - DBPfinger] at the predialytic stage predicts intradialytic hypotension.

Calculation of the diastolic blood pressure discrepancy with the finger-cuff blood pressure measurement at the beginning of dialysis helped predict intradialytic hypotension.