Evaluation of the Schiller BR-102 ambulatory blood pressure system according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation.

OBJECTIVE

To evaluate the Schiller BR-102 monitor for ambulatory blood pressure measurement according to the protocols of the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI).

DESIGN

The BHS protocol is divided into two parts. Part I, which is the part applicable to this study, comprises the main validation procedure and has five phases: before-use device calibration; in-use (field) phase; after-use device calibration; static device validation; and report of evaluation.

METHOD

Three Schiller BR-102 recorders passed the before-use device calibration test, after which they entered the in-use (field) assessment phase during which the three recorders were each worn by 10 subjects for 24 h, after which calibration was again assessed. Because there was no difference in results of calibration testing among the three devices, one was selected randomly and the main validation test was carried out on 85 subjects with a wide range of blood pressures both for the auscultatory mode and for the oscillometric mode using the Sphygmocorder. The results were analysed according to the BHS grading system from A to D. The data were also analysed according to the standard of the Association for the Advancement of Medical Instrumentation (AAMI), which stipulates that the mean difference between the test device and the standard shall be </= 5 mmHg with a standard deviation of </= 8 mmHg.

RESULTS

The Schiller BR-102 achieved a BHS grade B rating for systolic and diastolic blood pressures in the auscultatory mode and satisfied the criteria for accuracy of the AAMI protocol for systolic and diastolic blood pressures. In the oscillometric mode, the Schiller BR-102 achieved grade D for systolic blood pressure and grade B for diastolic blood pressure according to the BHS protocol and satisfied the AAMI criteria for diastolic but not systolic blood pressure. Applying the BHS and AAMI criteria to tertiles of blood pressure (low-pressure range < 130/80 mmHg, medium-pressure range 130-160/80-100 mmHg, high-pressure range > 160/100 mmHg) the Schiller BR-102 was less accurate in the high pressure range for diastolic blood pressure but more accurate for systolic blood pressure, achieving A/C grading, while satisfying the AAMI criteria both for systolic and for diastolic blood pressure in the auscultatory mode. In the oscillometric mode the device performed less accurately in the high-pressure range, achieving grade D/C, while failing to satisfy the AAMI criteria both for systolic and for diastolic blood pressure. The means+/-SD of the first mercury sphygmomanometer measurements were 143+/-32 mmHg for systolic blood pressure and 88+/-21 mmHg for diastolic blood pressure. Acceptability to subjects was good and the manufacturer's manual was satisfactory.

CONCLUSION

On the basis of these results, the Schiller BR-102 can be recommended for ambulatory blood pressure measurement in clinical practice using the auscultatory mode, but the oscillometric mode, which operates only if the device fails in the auscultatory mode, does not provide accurate measurements.