Accuracy and analysis of ambulatory blood pressure monitoring data

Two devices used to record blood pressure, the ambulatory blood pressure monitoring recorder and standard stethoscope and mercury column, were tested for accuracy against the direct intra-arterial blood pressure of patients at rest and during exercise. Recorders were found to be as accurate as mercury column measurement in patients at rest. A number of assessment techniques of ambulatory data are reviewed, including: calculation of mean or median pressures, assessment of blood pressure load, and integration of the area under the blood pressure curve over time. These have been applied during the daytime and nighttime hours. Blood pressure load and area under the blood pressure curve, using different threshold criteria for nighttime and daytime, are recommended because of their potentially closer relation to target-organ disease of hypertension than are office blood pressure readings.