SunTech 247 is an oscillometric blood pressure (BP) monitor manufactured by SunTech Medical Inc., Morrisville, North Carolina, USA. The aims of this study were (i) to determine its accuracy using the 1993 modified British Hypertension Society (BHS) protocol, the 2002 International Protocol (IP) and the 2002/2003 Association for the Advancement of Medical Instrumentation (AAMI) standards, (ii) to compare the performance of BHS protocol and IP.
Systolic BP (SBP) and diastolic BP (DBP) were recorded to the nearest 2 mmHg and measured with the arm supported at heart level. For each participant, nine sequential same arm measurements were taken by two trained observers, comparing the device to standard mercury sphygmomanometers. Procedures and data analysis were carried out following protocols guidelines.
First, we recruited 33 participants required by the IP. Then, data collection continued to obtain 85 participants for the BHS protocol/AAMI standard. Readings differing by less than 5, 10 and 15 mmHg for SBP and DBP fulfilled IP recommendations. According to the BHS protocol, for the better observer, the percentage of test device readings differing from the mercury standard by 5, 10 and 15 mmHg or less were: 92.9, 100 and 100% for SBP and 94.9, 98.8 and 99.6% for DBP. The mean differences± standard deviation between the device and mercury sphygmomanometer readings were 1.7±3.1 mmHg for SBP and 1.1±3.2 mmHg for DBP, achieving AAMI requirements. Standard deviation of mean differences were 2.4 for SBP and 2.1 for DBP, following the IP, and 3.1 and 3.2, respectively, for BHS protocol. The variance of all 99 differences (total deviance), with 98 degree of freedom, was 585.6 for SBP and 444.1 for DBP. The 33 differences obtained from the mean differences for each participant (between-subject variance), with 32 degree of freedom, were 275.6 and 152.1, respectively. F test was 1.83 with P = 0.0191 for SBP, and 1.07 (P = 0.3936) for DBP.
(i) The device achieved the requirements stated by the 2002 IP, fulfilled the standards stated by the AAMI, and on the basis of the standards indicated by the 1993 modified BHS protocol, can be classified as ‘A’ grade both for SBP and DBP. Therefore, SunTech 247 may be recommended for clinical use, (ii) IP and BHS protocol provide complementary features for device validation; the comparison of total deviance and between-subject variance confirms the estimates of IP authors for SBP.