[Nyctohemeral recording of blood pressure and heart rate. Preliminary study]

A preliminary report is presented of the 24 hour monitoring of blood pressure (BP) and heart rate (HR).

Ten normotensive persons, 5 of each sex with age between 30 and 65 (mean age 41.4) years. The recorder model TM 2420 made by A & D Co. of Japan was used. It has a blood pressure cuff and a recorder that utilized the Korotkoff sounds. It is possible to register the BP with intervals of 1 up to 60 minutes with a circadian division of up to 4 separate periods. A compact analyzer-computer with a printer processing unit prints each recording of PB and HR, the mean value and standard deviation of each period and of the total period of 24 hours.

During day time the systolic BP ranged from 96 to 140 mmHg (mean 118.7 +/- 11 mmHg) and the diastolic BP ranged from 67 to 90 mmHg (mean 75.2 +/- mmHg). In the period from 0 to 6 hours AM the systolic BP ranged from 81 to 115 mmHg (mean 102 +/- 13.7 mmHg) and the diastolic BP ranged from 63 to 86 mmHg (mean 67.2 +/- 9.3 mmHg). The mean HR ranged from 75 to 94 beats per minute (mean 84.3 +/- 31).

This lowering of BP during the night correlates with the variations of plasma nor-epinephrine. The main advantages of the circadian monitoring of blood pressure are: 1) to identify the false diagnosis of hypertension based on casual readings; 2) the significant correlation found between prognosis, end-organ-lesion and the pressure load (proportion of BP above normally) or the mean value of BP, while end-organ-lesion and prognosis correlates poorly with casual blood pressure.