[Nyctohemeral changes in arterial pressure in hospitalized subjects]

Systolic and diastolic arterial blood pressures (SBP, DBP) were measured in 181 consecutive patients (pts) by non-invasive method (oscillometric recorder SpaceLabs 90202). Hospitalised pts (N = 54) and ambulatory pts (N = 127) did not differ significantly in 24 hrs mean SBP, diurnal SBP, DBP nor heart rate (HR): respectively 132.9 vs 136.1 137.6 vs 138.2 86.2 vs 84.4 mmHg 79.6 vs 77.1 bpm. The circadian variation of HR was identical in the 2 groups. During night (0-6 hr AM) pressures decreased significantly less in hospitalised pts than in outpatients: respectively SBP - 6.4 vs - 17.9 p. cent DBP - 5.7 vs - 17 p. cent SBP day/SBP night ratio 1.06 vs 1.17 (p less than 0.001). This "equalization" was observed since the first day of hospitalisation, even if pts were not restricted to bed (pts in intensive care unit were excluded). It did not depend on age, sex, mean SBP nor antihypertensive treatments. Heart work, as evaluated by HR.SBP product, did not differ significantly during the day in the 2 groups. In hospitalised pts it decreased twice less and remains at a significantly higher level than in outpatients: respectively - 166 vs - 300 906 vs 792 cmHg/min (p less than 0.001). The standard deviation of SBP was significantly correlated with the SBP day/SBP night ratio (r = 0.64 p less than 0.001). The chronology of the circadian variations of HR and SBP are identical, but their amplitude differed in hospitalised pts suggesting that the regulatory mechanisms of HR and SBP are different.