Evaluation of activity distribution and circadian rhythm in patients with severe acquired brain injury

Research output: Book/anthology/dissertation/reportPh.D. thesis

Abstract

In this thesis, the results from four observational studies in patients with severe acquired brain injury (sABI) have been presented. Taken together, these studies provide an overview of both the daily activity distribution including time spent resting during the day, and the important day-to-day circadian rhythmicity during their initial in-hospital neurorehabilitation.
Study I indicated that patients with sABI have a relatively high activity level as compared to patients with a higher functional level in other studies. Activity levels were positively associated with functional abilities, and approximately 1/3 of their day (8am-8pm) was spent resting or sleeping equally likely to occur throughout the day.
Study II investigated day-to-day circadian rhythm in motor active patients using the daytime activity ratio (DAR). Half of the patients had established a consolidated circadian rhythm within the first week increasing to 80% after 3-4 weeks with a positive development over time. Change in DAR was not associated with a change in function.
In study III, a novel way of evaluating circadian rhythmicity, and rhythm characteristics when existing methods do not apply was presented. The model was able to ascertain if patients had a circadian rhythm per 24hr cycle and if so estimate rhythm characteristics. The model was applied in both motor active and motor in-active patients using accelerometry (ACC) and heart rate. Agreement between the ACC-model and the HR-model on the presence of rhythm was found in 53% of cycles in motor active patients. The mean difference of rhythm characteristics between the HR-model and the ACC-model was close to zero, but the limits of agreement were wide.
Study IV presented the results of the model on a patient level and exemplified the use of the model in the context of clinical reporting of body temperature (marker of infection) and functional abilities in select individuals. In 61% and 43% of the recorded 24hr cycles in motor active and motor in-active patients, respectively, a circadian rhythm was found. When circadian rhythm was present, the aggregated estimated night duration of both motor active and inactive was close to 8 hours and overall in accordance with the hospital rhythm. Yet, variability was high.
Original languageEnglish
Number of pages219
Publication statusPublished - 2021

Keywords

  • brain injury
  • rest activity cycles
  • actigraphy
  • diurnal rhythm
  • neurorehabilitation
  • circadian rhythm
  • electrocardiagram
  • behavioral mapping
  • daytime resting periods

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