Comparison of Direct vs. Indirect Blood Pressure Measurements on Treadmill and Bicycle in Hypertensive Responders

Abstract

Objectives: This study tested whether the systolic and diastolic blood pressures measured simultaneously by direct and indirect methods provide similar readings for blood pressure response during symptom-limited exercise on a treadmill and bicycle, and if it can be used to monitor blood pressure in hypertensive patients treated with β-blockers. Method:Comparisons were made with simultaneously determined intra-arterial catheter and auscultation measurements on a treadmill and bicycle. Eight hypertensive patients (41.9 ± 2.0 years) active participants in supervised aerobic programs (12.1 ± 1.2 METs work capacity) for at least 12 months were recruited to the study.Results: At rest, indirect systolic pressure was highly correlated with the direct method (r=0.85), with mean of 139 ± 7 and 134 ± 6 mmHg, respectively, at peak treadmill exercise (r=0.90), with mean of 198 ± 11 and 189 ± 9 and bicycle (r=0.92) with mean of 204 ± 10 196±9 mmHg respectively. Indirect diastolic blood pressure correlates well with intra-arterial at rest (r=0.82), with mean of 96 ± 11 and 88 ± 9 mmHg, respectively. However, at peak treadmill exercise, the correlation coefficient between the direct and the indirect methods was low (r=0.40), with mean of 105 ± 9 and 112 ± 12 mmHg, respectively. At peak bicycle exercise correlation was (r=0.58) with mean of 107 ± 9 and 112 ± 12 mmHg. Conclusions:These results suggest that at peak treadmill exercise and bicycle, the indirect method tends to bias low compared with direct therefore it is not valid for the assessment of diastolic pressure in hypertensive patients. Intensity should be considered when using cardiovascular variables as outcome measures.