Recent advances in blood pressure measurement technology: normalized blood pressure measurement with a double-cuff sphygmotonometer

Background In our previous studies of 24-h blood pressure measurement, basal blood pressure (minimum sleep-time blood pressure) showed the strongest correlation with hypertensive target-organ damage, We have currently devised a new accurate method of blood pressure measurement that entails recording casual blood pressure waves by means of a double-cuff sphygmotonometer, and attempted to normalize casual blood pressure to basal blood pressure. Methods The double-cuff sphygmotonometer records the arterial pressure wave, from which, using the formula (P-o = phi(i)(-1) X P-i), we attemped a normalization of casual blood pressure (P-i) to values close to those of the basal blood pressure (P-o). True basal blood pressure was measured by an indirect ambulatory blood pressure monitoring device (TM2425, A&D Co. Ltd., Tokyo, Japan). The subjects were 54 normotensive volunteers and 156 out-patients with essential hypertension [63 with World Health Organization (WHO)-II stage and 93 with WHO-I stage, including 47 subjects with white-coat hypertension] not receiving medication. Results The coefficient of correlation (r) between normalized diastolic blood pressure (Pd-o(')) and true diastolic basal blood pressure (Pd-o) was 0.82 (mean difference= 1 +/- 9.8 mmHg), that between normalized systolic blood pressure (Ps(o)(')) and true systolic basal blood pressure (Ps(o)) being 0.78 (1 +/- 13 mmHg) in 210 subjects. When an office mean blood pressure (MBP) of 116 mmHg was taken as the standard for identifying the WHO-I group, the sensitivity was 70% (65/93) and the specificity 67% (42/63), but when an MBPo [MBPo' = (Ps(0)' - Pd-0') / 3 + Pd-0'] of 89mmHg was the standard, the sensitivity was 82% (76/93) and the specificity 90% (57 / 63), both significantly higher than the corresponding values for office MBP (P < 0.05). Conclusion We devised a new double-cuff sphygrnotonometer and normalizing function (phi(-1)) and, ing these methods, calculated the normalized blood pressure in hypertensive out-patients, which may make it possible to identify degrees of severity of hypertension in terms of WHO stages. (C) 2001 Lippincott Williams Wilkins.