[Contribution of automatic sphygmomanometers for one-time measurement of blood pressure]

Due to high intra-individual variability of arterial blood pressure, single measurements provide only estimates of true actual values. Two or three recordings made in sequence in one or a few minutes' intervals are recommended in some clinical studies of antihypertensive therapy, with the aim of decreasing the variability. In order to examine the value of repeated measurements made on one occasion, four sequential resting recordings of blood pressure and heart rate made in one minute intervals with the automatic oscillometric Nippon Colin BP-103N sphygmomanometer were evaluated in 66 subjects, using the analysis of variance methods. Means of three recordings showed a significantly lower variability than single measurements (almost by one half), while the difference between three and four readings was not significant. The Page's rank test revealed that the first measurements are not uniformly the highest ones, and therefore the medians of three readings made in sequence are recommended as characteristics of resting blood pressure. An advantage of the oscillometric method is the possibility of measuring mean arterial pressure. The recorded values were significantly higher than those calculated from the systolic and diastolic pressures according to the current formula, being situated between one third and one half of the pulse pressure. The intra-individual coefficient of variation of the recorded mean arterial pressure was comparable with that of systolic and significantly lower than that of diastolic pressure.