Temperature variability during delirium in ICU patients: an observational study

PLoS One. 2013 Oct 23;8(10):e78923. doi: 10.1371/journal.pone.0078923. eCollection 2013.

Abstract

Introduction: Delirium is an acute disturbance of consciousness and cognition. It is a common disorder in the intensive care unit (ICU) and associated with impaired long-term outcome. Despite its frequency and impact, delirium is poorly recognized by ICU-physicians and -nurses using delirium screening tools. A completely new approach to detect delirium is to use monitoring of physiological alterations. Temperature variability, a measure for temperature regulation, could be an interesting component to monitor delirium, but whether temperature regulation is different during ICU delirium has not yet been investigated. The aim of this study was to investigate whether ICU delirium is related to temperature variability. Furthermore, we investigated whether ICU delirium is related to absolute body temperature.

Methods: We included patients who experienced both delirium and delirium free days during ICU stay, based on the Confusion Assessment method for the ICU conducted by a research- physician or -nurse, in combination with inspection of medical records. We excluded patients with conditions affecting thermal regulation or therapies affecting body temperature. Daily temperature variability was determined by computing the mean absolute second derivative of the temperature signal. Temperature variability (primary outcome) and absolute body temperature (secondary outcome) were compared between delirium- and non-delirium days with a linear mixed model and adjusted for daily mean Richmond Agitation and Sedation Scale scores and daily maximum Sequential Organ Failure Assessment scores.

Results: Temperature variability was increased during delirium-days compared to days without delirium (β(unadjuste)d=0.007, 95% confidence interval (CI)=0.004 to 0.011, p<0.001). Adjustment for confounders did not alter this result (β(adjusted)=0.005, 95% CI=0.002 to 0.008, p<0.001). Delirium was not associated with absolute body temperature (β(unadjusted)=-0.03, 95% CI=-0.17 to 0.10, p=0.61). This did not change after adjusting for confounders (β(adjusted)=-0.03, 95% CI=-0.17 to 0.10, p=0.63).

Conclusions: Our study suggests that temperature variability is increased during ICU delirium.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Temperature / physiology*
  • Cohort Studies
  • Delirium / diagnosis*
  • Delirium / physiopathology*
  • Humans
  • Intensive Care Units*
  • Linear Models
  • Monitoring, Physiologic / methods*
  • Netherlands
  • Retrospective Studies
  • Statistics, Nonparametric

Grants and funding

None of the author’s received funding for the study “temperature variability during delirium in ICU patients: an observational study” or for the preparation of the manuscript. Of the three studies from which patient data was used, only the Rivastigmine trial received funding. The Rivastigmine trial was funded by ZonMw, the Netherlands organisation for health research and development (grant number 80-82305-98-08109), the Netherlands Brain Foundation (grant number 2008(1).30), and Novartis, Basel, Switzerland (unrestricted grant). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.