Altered circadian rhythms in rectal temperature and circulating blood cells in intensive care unit patients

Abstract

We tried to document alterations of some circadian rhythms in intensive care unit (ICU) patients since they are presumably isolated from nychtemeral cycles of their natural environment. Hematological parameters were measured in 22 patients (12 comatose patients and 10 conscious patients). Blood samples used to determine the hematological parameters were obtained from each patient hourly at night and at 4-h intervals during the day during a 24-h span. Cosinor and student's t-test were used as statistical tools to test inter-group differences in the obtained time-series.

A statistically significant group circadian rhythm (P < 0.05) was detected for each studied parameter in comatose patients. In contrast, for the control group as a whole, the 24-h profiles of some studied parameters were altered. Alteration of rhythms might be explained by the effect of the manipulation of external synchronizers.

Keywords:

• brain injury
• comatose patient
• blood cells
• rectal temperature
• intensive care unit

Acknowledgments

The authors thank Prof. Alain Reinberg for manuscript preparation.