Validation of the TONOPORT V ambulatory blood pressure monitor according to the European Society of Hypertension International Protocol for Validation of Blood Pressure Measuring Devices in Adults.
BACKGROUND
It is now accepted that blood pressure measuring devices should be subjected to an independent evaluation of their accuracy before they are marketed for clinical use. The results of validation of the TONOPORT V blood pressure monitor for the measurement of ambulatory blood pressure according to the European Society of Hypertension International Protocol for Validation of Blood Pressure Measuring Devices in Adults are presented in this paper.


POPULATION
Thirty-three subjects were recruited from among staff and patients at Beaumont Hospital, Dublin, Ireland.


METHODS
The TONOPORT V monitor was connected to the Sphygmocorder, an audiovisual system for validation, which records blood pressure on tape and video for later analysis. Nine sequential same-arm measurements between the device and a standard mercury sphygmomanometer were recorded using the Sphygmocorder.


RESULTS
In phase 1, the TONOPORT V monitor produced 28 measurements within 5 mmHg, 37 within 10 mmHg and 40 within 15 mmHg for systolic blood pressure (SBP), and 26 within 5 mmHg, 38 within 10 mmHg and 44 within 15 mmHg for diastolic blood pressure (DBP). The mean differences were -2.2 (8.6) [mean (SD)] mmHg for SBP and +0.5 (7.2) mmHg for DBP. The TONOPORT V monitor passed all the criteria for both SBP and DBP. In phase 2.1, the TONOPORT V monitor had 56 measurements within 5 mmHg, 78 within 10 mmHg and 88 within 15 mmHg for SBP, and 60 measurements within 5 mmHg, 83 within 10 mmHg and 97 within 15 mmHg for DBP. The mean differences were -1.4 (8.7) mmHg for SBP and -0.2 (6.8) mmHg for DBP. The TONOPORT V monitor passed the criteria for DBP but failed to meet any of the criteria for SBP. In phase 2.2, 19 subjects had at least two of the differences within 5 mmHg and six subjects had no differences within 5 mmHg for SBP, and 22 subjects had at least two of the differences within 5 mmHg and six subjects no differences within 5 mmHg for DBP. The TONOPORT V monitor failed to meet the criteria for SBP and for DBP.


CONCLUSIONS
The TONOPORT V monitor cannot be recommended for clinical use in an adult population because it records SBP inaccurately and because it records DBP inaccurately in an unacceptably high proportion of people.