A validation study of the Del Mar Avionics Pressurometer IV according to AAMI guidelines

Guidelines for the evaluation of automatic non-invasive blood pressure (BP) measurement devices have recently been established by the Association for the Advancement of Medical Instrumentation (AAMI). We evaluated the Del Mar Avionics Pressurometer IV (P4) in tests on 109 subjects, according to these guidelines. Three readings by two observers using a double stethoscope were first compared to each other to determine a standard and then averaged and compared to readings obtained using the P4. The two observers agreed within +/- 6 mmHg or 90% of the readings for both systolic and diastolic BP, with correlations of 0.99 and 0.98 for systolic and diastolic BP, respectively. The observers and the P4 in turn agreed to within +/- 6 mmHg for 85% of the readings for systolic BP, with a correlation of 0.98, and 65% of the readings for diastolic BP, with a correlation of 0.69. The correlations for both systolic and diastolic BP increased to 0.99 when readings were restricted to those obtained in individuals who fulfilled our previously defined calibration criterion of +/- 5 mmHg. In addition, we evaluated nine measurements of performance over 60 ambulatory recordings. The most serious problem was that of missing data which occurred in 85% of the recordings, primarily during sleep hours, and was generally attributed to either detection of Korotkoff sounds below 40 mmHg or a failure to detect Korotkoff sounds.