An evaluation of the Rastreometro, a new device for populational screening for high blood pressure in developing...

To test a simplified blood pressure device called Rastreometro that could be used by the Health Agents.

The Rastreometro has been developed from an ordinary aneroid sphygmomanometer, in which the numeric display is covered by an adhesive with a red zone, indicating pressures equal or above 140 mmHg and a yellow zone indicating pressures below 140 mmHg. The onset of oscillations of the aneroid needle is taken as an indication of the systolic pressure value. The measurements made by the Rastreometro were compared with those made by the auscultatory method, and were carried out in 268 patients, by two operators. The influence on the results of confounding variables such as age, gender, BMI, arm length, upper arm circumference, skin colour and antihypertensive treatment were taken into consideration, as well as intra and interobserver variation.

In the whole group, sensitivity was 95.1%, specificity was 63.1%, positive predictive value was 62.4% and negative predictive value was 95.3%. Hypertensive treatment significantly affected specificity, 32.7% as compared to 77.8% for the non-treated group. Both operators improved their results over time.

This study suggests that the Rastreometro technique, as a screener for hypertension, has good sensitivity. Concerning specificity, it is acceptable, provided the patient is not on regular antihypertensive treatment. In this latter situation, it can be improved by a proper standardization of the method to read the systolic pressure by needle oscillations. Furthermore, the use of this technique requires well trained operators.