Temporal analysis of blood pressure by ambulatory 24 H blood pressure monitoring.

In order to study the circadian rhythm of BP in man, we performed 24-hour non invasive BP on 15 hospitalized patients. Each subject was monitored twice, with an interval of 24-48 h between the two monitorings. In 14 of the 15 subjects MBP showed a statistically significant circadian rhythm. The curve fitted by the single cosinor method to the mean of the first rhythmometric measurements performed on all 15 subjects was characterized by an acrophase at 12.53, an amplitude of 4.68 mmHg and a mesor of 87.49 mmHg. The same parameters for the second rhythmometric measurements were: acrophase at 13.57, amplitude 4.1 mmHg and mesor 88.35 mmHg. In both cases, overall circadian rhythm resulted to be similar in all the subjects (p less than 0.01). Multivariate analysis of variance showed that each subject has his own characteristic circadian rhythm. Our findings support the hypothesis of a identifiable circadian rhythm of BP in man.