Modelling fluid accumulation in the neck using simple baseline fluid metrics: implications for sleep apnea

Area of Science:

• Physiology
• Sleep Medicine
• Cardiovascular Research

Background:

• Obstructive sleep apnea (OSA) is a prevalent adult respiratory disorder.
• Sedentary behavior is linked to increased diurnal leg fluid volume (LFV).
• Increased LFV may shift to the neck during sleep, exacerbating OSA.

Purpose of the Study:

• To investigate correlations between baseline leg fluid retention metrics and neck fluid volume (NFV).
• To develop predictive models for neck fluid accumulation.
• To explore the role of leg fluid in OSA pathogenesis.

Main Methods:

• Simultaneous continuous recording of LFV and NFV in healthy men while standing and supine.
• Simple regression analysis to assess correlations between baseline LFV, neck circumference (NC), and changes in LFV with neck outcomes (ΔNC, ΔNFV90).
• Exhaustive grid search for optimal predictive models of fluid accumulation.

Main Results:

• Strong positive correlations observed between baseline LFV (standing and supine) and the change in NFV (ΔNFV90).
• Predictive models for ΔNFV90 incorporated baseline standing LFV and baseline NC with change in LFV.
• Models for predicting change in NC (ΔNC) effectively combined baseline LFV and NC.

Conclusions:

• Elevated baseline LFV appears to contribute to increased neck fluid accumulation.
• These findings support the hypothesis that sedentary lifestyles may promote OSA by increasing baseline LFV.
• Combined baseline fluid metrics offer improved prediction of neck circumference changes during supine positioning.