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Validation of the Omron HEM-650 wrist blood pressure device using the British Hypertension Society protocol in emergency patients in Hong Kong
Abstract
Objectives:
Automated wrist cuff blood pressure (BP) devices are more compact and easier to use, particularly when access to the upper arm is restricted, for example in emergencies.
Material and methods:
We tested the Omron HEM-650 wrist device using the validation criteria of the British Hypertension Society (BHS) protocol in a major emergency department (ED) in Hong Kong. 85 patients had three measurements each by both the Omron HEM-650 wrist device and the mercury sphygmomanometer. The conventional automated BP with arm cuff was also measured using an oscillometric (Colin BP-88S NXT) device for comparison.
Results:
The Omron HEM-650 achieved a grade B for both systolic and diastolic BP and demonstrated acceptable accuracy and reliability in Chinese patients in the emergency setting.
Conclusion:
The Omron HEM 650 wrist device can be recommended for use in adult emergency patients. Further research is warranted for its use in pregnant women and critically ill patients.
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For the accurate indirect measurement of blood pressure (BP), the American Heart Association (AHA) now recommends that cuff size should be based solely on limb circumference. We studied prevailing cuffing habits and compared them with newly revised AHA guidelines. Monitoring our staff's cuff applications, we found that "miscuffing" occurred in 65 (32%) of 200 BP determinations on 167 unselected adult outpatients, including 61 (72%) of 85 readings taken on "nonstandard" size arms. Undercuffing large arms was the most frequent error, accounting for 84% of the miscuffings. Considering that miscuffing distorts BP readings by an average of 8.5 mm Hg systolic and 4.6 mm Hg diastolic, we can improve the accuracy of our BP determinations by remarking our cuffs and using the new AHA guidelines.
Self-measurement of blood pressure (BP) might offer some advantages in diagnosis and therapeutic evaluation and in patient management of hypertension. Recently, wrist-cuff devices for self-measurement of BP have gained more than one-third of the world market share. In the present study, we validated wrist-cuff devices and compared the results between wrist- and arm-cuff devices. The factors affecting the accuracy of wrist-cuff devices were also studied.
The research group to assess the validity of automated blood pressure measuring device consisted of 13 institutes in Japan, which validated two wrist-cuff devices (WC-1 and WC-2) and two arm-cuff devices (AC-1 and AC-2). They used a crossover method, where the comparison was done between auscultation, by two observers by means of a double stethoscope on one arm and the device on the opposite arm or wrist.
There was good inter-observer agreement for the auscultation method in each institute (systolic blood pressure (SBP), -0.1 +/- 2.8 mmHg; diastolic blood pressure (DBP), -0.1 +/- 2.6 mmHg, n = 498). The mean difference between auscultation and the device was minimal both in arm-cuff devices (mean difference for AC-1, 2.2/1.9 mmHg, n = 97 and for AC-2, 5.1/2.9 mmHg, n = 136, SBP/DBP) and wrist-cuff devices (mean difference for WC-1, -2.1/1.2 mmHg, n = 173 mmHg and for WC-2, -2.3/-5.6 mmHg, n = 92). The standard deviation of the difference (SDD) in wrist-cuff devices, however (SDD for WC-1, 9.7/7.3 mmHg and for WC-2, 10.2/8.6 mmHg), was larger than that of the arm-cuff devices (SDD for AC-1, 5.6/6.6 mmHg and for AC-2, 6.3/5.1 mmHg). Grading of AC-1 and AC-2 based on criteria of British Hypertension Society was A/A and B/A, respectively, while that of WC-1 and WC-2 was C/B and D/B, respectively. Using the same validation protocol, the results of validation for one device were divergent in each institute. In wrist-cuff devices, the BP value obtained in palmar flexion was significantly higher and that obtained in palmar dorsiflexion was significantly lower than that in palmar extension. In some cases, finger plethysmogram did not disappear during maximum inflation of the wrist-cuff (congruent with 250 mmHg), even in palmar extension and especially in palmar flexion, suggesting incomplete obstruction of radial and/or ulnar arteries during inflation.
The results suggest that wrist-cuff devices in the present form are inadequate for self-measurement of blood pressure and, thus, are inadequate for general use or clinical and practical use. However, there is much possibility in wrist-cuff device and the accuracy and reliability of wrist-cuff device are warranted by an improvement of technology.
To determine whether the Omron HEM637 wrist model with the wrist positioning sensor turned on (Son) is more accurate relative to upper arm auscultation by trained professionals than when the sensor was manually turned off (Soff).
Forty-four subjects, at least 30 years old, had repeated, sequential dual-observer upper arm auscultatory measurements (5 to 6 each) and oscillometric Omron HEM637 wrist measurements (4 each). Nineteen subjects were assigned to the wrist sensor On group and 25 were assigned to the wrist sensor Off group. A total of 425 auscultatory and 164 wrist measurements were analyzed.
The Omron HEM-637 measured the blood pressure (BP) with equal accuracy to the observers using the auscultatory technique (difference -1.37 +/- 8.51/3.47 +/- 8.07 mm Hg, P =.71/.14). The wrist sensor did improve the accuracy of the measurements compared to the subjects that had the sensor deactivated. The sensor On group (Son) measured the systolic BP (0.82 +/- 9.83 mm Hg) and diastolic BP (-0.72 +/- 9.07 mm Hg) statistically the same as by auscultation (P =.86 for systolic BP and P =.83 for diastolic BP). The sensor Off (Soff) group measured the SBP (-3.03 +/- 7.12 mm Hg) and diastolic BP (-5.56 +/- 6.68 mm Hg) statistically different than auscultation (P =.46 for systolic BP and P =.02 for diastolic BP). The higher (negative) measurement for both the systolic BP and diastolic BP suggests that the average position of the wrist was 1.75 inches (4.4 cm) below the heart level in this group with the sensor off.
This study demonstrated that the Omron HEM-637 monitor with a wrist sensor more accurately measured BP compared to the same model with the sensor turned off.
Whether blood pressure (BP) measured at the wrist differs from blood pressure measured at the arm is not well known. The aim of this study was to compare the BP readings obtained at the arm with those obtained at the forearm and to assess whether the wrist-arm discrepancies were related to subjects' clinical characteristics.
We measured blood pressure at the forearm and at the upper arm in 85 subjects using conventional sphygmomanometry. Wrist-arm blood pressure discrepancies were assessed in relation to gender, age, body mass index, skin-fold thickness, arm size, blood pressure level, and arterial compliance measured with the HDI/Pulsewave CR-2000.
Blood pressure measured at the wrist consistently overestimated blood pressure taken at the arm with a mean (+/-SD) discrepancy of 8.2 +/- 9.7/9.2 +/- 6.4 mmHg. The systolic blood pressure differences were greater in men than in women (p=0.006) and, among the men, varied according to arm adiposity (positive association, p=0.01). In men, diastolic blood pressure differences correlated with diastolic blood pressure level (negative association, p=0.01). Among the women, only age (p=0.04) was a significant positive independent predictor of the wrist-arm diastolic BP differences.
These results indicate that forearm blood pressure measurement markedly overestimates upper arm blood pressure and that the between-site difference may vary from subject to subject. Wrist blood pressure measurement is not a valid alternative to traditional measurement at the arm and its use should be discouraged.
The market for wrist devices for self-measurement is growing and these devices are becoming popular among the patients. Despite widespread use of these devices, there is limited published evidence for their accuracy and reliability in the different patient groups. The objective of this study was to evaluate the accuracy of the Omron 637IT (Omron Healthcare Europe B.V, Hoofddorp, Netherlands) wrist blood pressure device against the mercury sphygmomanometer in the elderly according to the International Protocol criteria.
Seventy-six patients older than 65 years of age were studied and classified on the basis of the range of the International Protocol. Blood pressure measurements at the wrist with the Omron 637IT were compared with the results obtained by two trained observers using a mercury sphygmomanometer. Nine sequential blood pressure measurements were taken. A total of 33 participants with arm circumference distributed randomly were selected for the validation study. During the validation study, 99 measurements were obtained for comparison in the 33 participants. The first phase was performed on 15 participants, and if the device passed this phase, 18 more participants were selected.
Mean discrepancies and standard deviations of the sphygmomanometer device were -0.3+/-6.5 mmHg for systolic blood pressure and 2.8+/-4.8 mmHg for diastolic blood pressure in the study group. The device passed phase 1 in 15 participants. In phase 2.1, from the total 99 comparisons, 66, 87, and 95 for systolic blood pressure and 69, 92, and 97 for diastolic blood pressure were <5, <10, and <15 mmHg, respectively. In phase 2.2, 24 participants had at least two of the differences within 5 mmHg and three participants had no differences within 5 mmHg for systolic blood pressure. For diastolic blood pressure, 24 participants had at least two of the differences within 5 mmHg and three participants had no differences within 5 mmHg. The Omron 637 IT passed the phase 2.1 and 2.2 in the elderly group.
The Omron 637IT wrist blood pressure device passed according to the International Protocol criteria and can be recommended for use in the elderly.
Wrist blood pressure devices are becoming popular for the self-measurement of blood pressure. Despite widespread use of these devices, there is limited published evidence for their accuracy and reliability. In this study, we assessed the accuracy of the Omron 637IT wrist blood pressure device against the mercury sphygmomanometer in adults and obese adults according to the International Protocol criteria.
A hundred and thirty-one participants were studied and classified on the basis of the International Protocol range. Blood pressure measurements at the wrist using the Omron 637IT were compared with the results obtained by two trained observers using a mercury sphygmomanometer. Nine sequential blood pressure measurements were taken. Initially, 33 participants with random arm circumferences were selected for the first validation study. Then, the device was evaluated in adults with arm circumferences equal to or higher than 34 cm. During each validation study, 99 measurements were obtained for comparison from the 33 participants. The first phase was performed on 15 participants, and, if the device passed this phase, 18 more participants were selected.
Mean discrepancies and standard deviations of the sphygmomanometer device were 0.5+/-6.2 mmHg for systolic blood pressure and 0.1+/-3.7 mmHg for diastolic blood pressure in the adult group. The device passed phases 1 and 2 in 33 participants. Mean discrepancies and standard deviations of the sphygmomanometer device were 1.8+/-6.6 mmHg for systolic blood pressure and 1.6+/-4.7 mmHg for diastolic blood pressure in the obese adult group. The device passed phases 1 and 2 in 33 participants in this group.
The Omron 637IT passed according to the International Protocol criteria and can be recommended for use in adults and obese adults.
Short report: An outline of the revised British Hypertension Society protocol for the evaluation of blood pressure measuring devices
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Accuracy and reliability of wrist-cuff devices for self-measurement of blood pressure
- M Kikuya
- K Chenon
- Y Imai
- E Goto
- M Ishii
Kikuya M, Chenon K, Imai Y, Goto E, Ishii M, on behalf of the Research Goup. Accuracy and reliability of wrist-cuff devices for self-measurement of blood pressure. J Hypertension. 2002;20:629-38.