Circadian pattern of plasma electrolytes in intensive care unit patients

Abstract

Many physiological functions exhibit circadian rhythmicity. These functional rhythms are driven in part by the circadian clock, which plays an important role in maintaining stability of internal conditions. The present study was designed to evaluate the circadian rhythm of plasma chemistry variables in intensive care unit patients (they are isolated from nychtemeral cycles of their natural environment). Two groups participated in the study: comatose patients (n = 12), and non-comatose ones (n = 10). Blood samples were obtained from comatose patients hourly at night and at 4-h intervals during the day during a 24 h span. For the second group, blood samples were obtained at 4-h intervals during 24 h spans. Diurnal rythmicity of plasma electrolytes was noted in both groups (Cosinor p< 0.05) (except chloride for comatose patients). These results suggest that coma did not affect the rhythmicity of chemistry variables. The shift in phases may explain the effect of the absence of the synchronizers (essentially sleep/wake and light/dark cycle).

Keywords:

• chemistry variables
• circadian rhythms
• coma
• intensive care unit patients
• synchronizers