Effects of measurement intervals on the values of repeated auscultatory blood pressure measurements.

Objective: For repeated measurements of blood pressure (BP) using the auscultatory method, current guidelines recommend intervals of 1-2 minutes; however, evidence to support this recommendation is insufficient. In the present study, the effects of intervals among repeated BP measurements using the auscultatory method were evaluated.Methods: Systolic and diastolic BPs were measured using the auscultatory method in 37 participants. The measurements were repeated 5 times each at intervals of 15, 30, 60, 90, and 120 seconds. The changes in the BP along with the increasing the number of repetitions were assessed at each measurement interval using a linear mixed model.Results: With an increasing number of measurements, the systolic and diastolic BPs showed significant progressive decrease and increase (p < 0.05), respectively, when the measurement interval was 15 seconds. However, the precision of BP measurements was not affected by performing the measurements at intervals of 30 seconds or longer.Conclusion: Repeated BP measurements using the auscultatory method need to have an interval of at least 30 seconds, which is shorter than the intervals recommended by the current guidelines.

Accuracy of automated cuff blood pressure monitors in special populations: International Organization for Standardization (ISO) Task Group report and call for research.

OBJECTIVE: Automated cuff blood pressure (BP) devices are widely used for ambulatory, home, and office BP measurement. However, an automated device, which is accurate in the general adult population may be inaccurate in some special populations. A 2018 Collaborative Statement by the US Association for the Advancement of Medical Instrumentation, the European Society of Hypertension, and the International Organization for Standardization (ISO) considered three special populations requiring separate validation (age <3 years, pregnancy, and atrial fibrillation). An ISO Task Group was appointed to identify evidence for additional special populations. METHOD: Evidence on potential special populations was identified from the STRIDE BP database, which performs systematic PubMed searches for published validation studies of automated cuff BP monitors. Devices that passed in a general population, but failed in potential special populations were identified. RESULTS: Of 338 publications (549 validations, 348 devices) in the STRIDE BP database, 29 publications (38 validations, 25 devices) involved 4 potential special populations: (i) age 12-18 years: 3 of 7 devices failed but passed in a general population; (ii) age more than 65 years: 1 of 11 devices failed but passed in a general population; (iii) diabetes type-2: 4 devices (all passed); (iv) chronic kidney disease: 2 of 7 devices failed but passed in a general population. CONCLUSION: Some evidence suggest that the automated cuff BP devices may have different accuracy in adolescents and in patients with chronic kidney disease than in the general population. More research is needed to confirm these findings and investigate other potential special populations.

Comparison of the Omron RS6 wrist blood pressure monitor with the positioning sensor on or off with a standard mercury sphygmomanometer.

OBJECTIVE: The aim of the present study was to evaluate the measurement accuracy of Omron RS6 with positioning sensor on (PSON) in comparison with Omron RS6 with positioning sensor off (PSOFF). The Omron RS6 has passed the 2010 version of the European Society of Hypertension International Protocol previously. METHODS: A total of 85 adult participants (39 male and 46 female) were recruited. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were sequentially measured using a standard mercury reference sphygmomanometer (ERKA 3000; two observers) and Omron RS6 with PSON or PSOFF. RESULTS: A total of 85 participants (39 men, 46 women) were included in this study, with a mean age of 53.5±16.4 years. SBP at entry was 133.0±19.9 mmHg and DBP was 81.3±11.8 mmHg. The two observers for SBP and DBP measurements were in good agreement, with agreements of -0.2±1.5 mmHg for SBP and -0.2±1.5 mmHg for DBP, respectively. The mean difference between PSON readings and readings from the standard device was -2.6±6.1 mmHg for SBP and -1.4±4.8 mmHg for DBP. The differences in PSOFF readings were -4.5±6.9 and -3.2±5.4 mm Hg, respectively (P<0.01; PSON vs. PSOFF). A higher proportion of patients had a small deviation (≤5 mmHg) from the reference device when the positioning sensor was on (65 vs. 54% for SBP and 76 vs. 65% for DBP readings). Using the positioning sensor, the variation in wrist height compared with PSOFF decreased. CONCLUSION: The Omron RS6 position sensor is an important function for a wrist device that improves measurement accuracy by decreasing variations in wrist height.

A new method for determining the servo reference value (Vo) of the volume-compensation method.

A new technique for swiftly determine a servo reference value (Vo) of the volume-compensation method was developed. To determine the Vo values, high frequency vibration (frequency: 20 Hz, pulse pressure: 10 mmHg) was superimposed on cuff pressure (Pc), and artificially produced arterial wall oscillation was detected as photoplethys-mographic (PG) pulsation signal. In this signal, maximum oscillation points were observed when the mean value of Pc is equal to blood pressure, and Vo value was then determined from the mean level of PG signal at this maximum point. The values obtained by this method coincide well with those obtained by the previous method (the volume-oscillometric method), indicating the validity of the present method.