The present study applies the "fractal interpolation" (FI) to 24-h blood pressure nonivasively and ambulatorily monitored over a day-night period in secondary hypertensives. The purpose is the evaluation of the prevalence for a "presumptive risk" (PR) of hypertensive crisis.The study was carried out in 108 cases of secondary hypertension, who were non-invasively and ambulatorily monitored for their 24-h blood pressure values. The FI was applied to the time-qualified values of the mean arterial pressure.The PR of hypertensive crisis was found in 11% of the investigated secondary hypertensive patients. Such a risk shows a not significant prevalence in dippers as compared to non-dippers, and in those who showed a significant blood pressure circadian rhythm as compared to those who showed the blood pressure circadian rhythm to be abolished. Additionally, a not significant difference was found between the cases "at risk" and "not at risk" as far as the spectrum of harmonic formants of the 24-h blood pressure pattern is concerned.The PR of hypertensive crisis is not associated with the dipping/non-dipping phenomenon as well as the circadian rhythmicity of blood pressure. Its occurrence in secondary hypertensives is essentially related to the disorder that is detectable in blood pressure non-linear variability. Therefore, such a risk may be caused by neurovegetative mechanisms which notoriously confer a non-linear chaotic variability to 24-h blood pressure pattern.
Abstract The circadian rhythms of blood pressure (BP) and heart rate (HR) were documented in 30 patients for a 24‐hour period before and during the 24 hours that included unilateral surgery for senile cataract or retinal detachment. The patients were premedicated with diazepam. Anaesthesia was induced at a fixed time (09.00) in all patients with thiopentone, and muscle relaxation was with pancuronium. Maintenance was with enflurane in 15 patients and with fentanyl and droperidol in the rest. Though the intraoperative changes in haemodynamic parameters were dissimilar with the two types of maintenance agents, but both types had a similar effect on the circadian rhythms of blood pressure and heart rate. Whereas preoperatively the BP and HR circadian rhythms were nearly in phase, with their peaks in the late morning to early afternoon, the postoperative rhythms underwent a dissociation to a phase shift in the BP 24‐h pattern. The phase effect may be hypothetically attributed to direct pharmacological actions or to masking effects.
