Does sequential automated measurement improve the estimate of resting blood pressure?

Repeated blood pressure measurements made in sequence over short time intervals have been recommended in some studies of antihypertensive drugs, with the aim of improving the estimate of 'true' resting BP values. In order to examine this claim, the variance of four sequential automatic recordings of BP and heart rate was evaluated in 66 subjects. The oscillometric Nippon Colin BP-103N sphygmomanometer has been previously shown by our group to give accurate and consistent measurements of BP. The means and medians of three sequential readings, by significantly decreasing the variability, were found to be superior to single measurements. The recorded mean arterial pressures were significantly higher than those calculated according to the current formula, on average by 3.6 mmHg, being situated between one third and one half of the distance between the systolic and diastolic pressures. The Page's rank test revealed that the first measurements were not uniformly the highest ones. Since the variability of the first to third BP values did not differ, medians of the three sequential recordings made at one minute intervals can be recommended as a standard BP characteristic.