Relationship between disruption of rhythmicity and reentrainment in surgical patients

Urine samples for assay, temperature, heart rate, and blood pressure were collected daily at 2-h intervals from 11 consenting subjects undergoing abdominal surgery, as well as 10 age-and sex-matched control subjects. Alterations in level, and timing of circadian excretion of catecholamine metabolites, adrenal cortical hormones, sodium, potassium, creatinine, and vital signs following surgery were measured. Data were examined to determine if a relationship exists between the degree of circadian alteration and the subject's return to typical circadian profiles. The data suggest that certain circadian rhythms of hospitalized subjects were altered and uncoupled from external stimuli. In addition, subjects with less disruption in some variables following surgery regained rhythmicity more quickly than more disrupted subjects. These findings suggest that health professionals should individualize patient care to promote rhythmicity. In addition, patient assessment should consider individual circadian patterns and disruption following surgery.