DIURNAL BLOOD-PRESSURE CURVE IN CHILDREN AND ADOLESCENTS

Objective To investigate the diurnal blood pressure curve in healthy n ormotensive children, Thirty-one children were re-examined after a med ian interval of 123 days in order to study the reproducibility of the diurnal profile. Subjects Twenty-four-hour ambulatory blood pressure m onitoring and conventional blood pressure readings were obtained in 22 8 normotensive children, whose ages ranged from 6 to 16 years and of w hom 116 were boys and 112 girls. Results The conventional blood pressu re averaged 99 +/- 11/57 +/- 9 mmHg in boys and 98 +/- 12/56 +/- 9 mmH g in girls (means +/- SD); the corresponding 24 h pressures were 111 /- 7/66 +/- 5 mmHg and 109 +/- 7/65 +/- 5 mmHg, respectively. Of the c hildren, 83% had a significant diurnal blood pressure rhythm for systo lic pressure and 89% for diastolic pressure, The nocturnal blood press ure fall was normally distributed, averaging 12.0 +/- 6.3 mmHg systoli c and 14.2 +/- 5.9 mmHg diastolic. There was no evidence for a bimodal distribution, The amplitude of the diurnal blood pressure curve, dete rmined by the Fourier approach, was positively skewed with a mean of 1 2.5 +/- 4.2 mmHg for systolic and 14.0 +/- 4.1 mmHg for diastolic bloo d pressure. The daily blood pressure maximum occurred at 1344 +/- 4 h 46 min for systolic and 1321 +/- 4 h 22 min for diastolic blood pressu re. For systolic blood pressure the cumulative sum (cusum)-derived cir cadian alteration magnitude was 1.7 +/- 6.2 mmHg higher in boys than i n girls, whereas the cusum plot height was also 7.3 +/- 27.0 mmHg x h higher in male subjects. The repeatability coefficient (2 SD of the di fference between paired recordings, expressed as a percentage of nearl y maximal variation) was 80% for the conventional systolic pressure an d 40% for the conventional diastolic blood pressure. The repeatability coefficients for the ambulatory blood pressure levels varied from 32 to 45% and for the parameters describing the diurnal blood pressure pr ofile from 42 to 78%. Conclusion A significant diurnal blood pressure rhythm is observed in most normotensive children and adolescents, Ther e is no evidence for a bimodal distribution of the I nocturnal blood p ressure fall. The reproducibility of the parameters of the diurnal blo od pressure curve tended to be less than that of the ambulatory blood pressure level. Thus, one 24 h recording is probably insufficient to c haracterize a child's diurnal blood pressure profile fully.