[Quality assurance in Riva-Rocci blood pressure measurement: simultaneous sphygmomanometry with open and covered pressure display].

The indirect measurement of arterial blood pressure according to Riva-Rocci is one of the most frequently performed medical diagnostic procedures. When properly performed, this method yields accurate readings compared with intraarterial measurements. However, measurements by means of conventional sphygmomanometers are subject to observer error and variability. Therefore, to eliminate important sources of bias (terminal digit preference of the observer, rate of inflation and deflation of the cuff), and to quantify interobserver variability, a new sphygmomanometer has been developed. The new instrument makes possible "simultaneous-blind" blood pressure readings by two observers, according to the Riva-Rocci method. Simultaneous-blind blood pressure readings were made by four observers with experience in blood pressure determination. In 448 measurements made under resting conditions, values obtained by different observers with the new device were very consistent with each other: there were no differences in 50% of systolic and 43% of diastolic measurements. Differences of more than 5 mmHg were observed only in 9% of the systolic and 11% of the diastolic measurements. In 165 measurements made during exercise, the differences between blood pressure readings by different observers were larger (more than 5 mmHg in 40% of systolic and 35% of diastolic values). This variability among observers may be substantial in blood pressure readings made in therapeutic and epidemiologic studies, even when the observers are carefully selected and trained. Compared with the conventional open measurements, blind measurements (n = 100) gave mean values 2 mmHg lower, depending on heart rate and cuff deflation rate. The new sphygmomanometer allows quantification and control of the variability among observers during both open and blind measurements.