Decreased physiologic variability as a generalized response to human endotoxemia.

Area of Science:

• Physiology
• Immunology
• Systems Biology

Background:

• Understanding the human body's response to inflammation is crucial for critical care.
• Physiological variability reflects complex system dynamics and health status.

Purpose of the Study:

• To investigate how transient systemic inflammation affects the variability of diverse physiological measures.
• To determine if systemic inflammation alters the time-series behavior of inflammatory response indicators.

Main Methods:

• Prospective study with eight healthy volunteers serving as their own controls.
• Intervention involved intravenous Escherichia coli endotoxin administration on a treatment day.
• Physiological data (heart rate, neutrophil function, cortisol) were collected via continuous ECG and serial blood sampling.

Main Results:

• Time-series data for heart rate (R-R intervals), neutrophil phagocytosis, and plasma cortisol were analyzed.
• Approximate entropy analysis revealed a significant decrease in variability for all measured parameters.
• This indicates an increase in the regularity of these physiological functions during endotoxemia.

Conclusions:

• Systemic inflammation leads to a generalized increase in physiological regularity across divergent organ systems.
• Decreased variability in organ function is a hallmark response to endotoxemia in humans.
• These findings highlight the systemic impact of inflammation on physiological control mechanisms.