Circadian systolic and diastolic hyperbaric indices of high school and college students

Apparently healthy North American (mostly Minnesotan) students, 117 boys and 147 girls, 14-21 years of age, self-measured blood pressure at 1 h or longer intervals for spans ranging from 24 h over several weeks to much longer spans. Each series was analyzed for a circadian rhythm by the single cosinor fit of a 24-h cosine curve. The mesor, amplitude and acrophase thus obtained were used for the determination of a mean acrometron, i.e. the mean of the sum of mesor + amplitude for each individual investigated. A circadian hyperbaric impact (HBI) was then computed as the tension-time product represented by the area under the fitted cosine curve and above the acrometron as a critical value. A highly skewed distribution of these HBIs was found: the HBI for systolic and diastolic blood pressure equalled 0 in 64 and 49 of the series on boys and 78 and 72 of the series on girls, respectively. Individuals singled out as outliers by the HBI are recommended for traking, some with and some without eventual intervention. The overall HBI is a step toward assessing the values that may lie above some group reference value, assuming a fixed rather than a likely-changing threshold for the damaging effect and further assuming the linearity of any impact, if not damage, along the scales of pressure and time. The overall HBI, based on such unvalidated approximations, will have to be complemented by an index related to the changes that lie outside a chronodesm with focus both upon the pressures that are too low as well as upon those that are too high.