Circadian rhythm in critically ill patients: Insights from the eICU Database

Area of Science:

• Critical Care Medicine
• Circadian Biology
• Physiology

Background:

• Circadian rhythms influence physiological processes, but their disruption in critically ill patients is not fully understood.
• Understanding circadian variation in intensive care unit (ICU) patients is crucial for optimizing care and predicting outcomes.

Purpose of the Study:

• To investigate circadian variation in blood pressure (BP) among critically ill patients.
• To assess the association between circadian rhythm characteristics and clinical factors, including severity of illness and survival.

Main Methods:

• Analysis of hourly BP data from over 23,000 ICU patients using cosinor models.
• Calculation of circadian rhythm amplitude and peak time, correlating these with clinical data and outcomes.

Main Results:

• A dampened 24-hour BP rhythm (lower amplitude) and phase shifts were observed in sicker patients, those with sepsis, organ dysfunction, or on mechanical ventilation.
• Higher BP rhythm amplitude correlated with shorter ICU and hospital lengths of stay and lower in-hospital mortality.
• Timing of BP peak was significantly associated with in-hospital mortality.

Conclusions:

• Circadian rhythm disruption (dampening and phase shifting) is prevalent in critically ill patients, particularly the most severe.
• These circadian alterations are associated with longer hospital stays and increased mortality risk.
• Restoring or preserving circadian rhythmicity may be a therapeutic target in critical care.