The cardiac chemoreflex sensitivity (cCRS) and the influence of respiration

Introduction

Assessment of cCRS may be a predictor of serious arrhythmic events after survived sudden cardiac death. However, chemoreceptor (CR) stimulation produces not only cardiovascular but also respiratory responses. The aim of this study was to correct the respiratory influence on apparent values of cCRS.

Methods

The cCRS was assessed in 47 healthy volunteers during free breathing (FB). Twenty subjects underwent further monitoring during controlled breathing (CB, fixed minute ventilation). Peripheral arterial CTs were stimulated by 5 min of hypoxia (10% O₂ in N₂). Cardiac CRS was calculated asΔ heart rate interval/ΔpO₂. We developed a mathematical model to reduce the respiratory influence on cCRS, and calculated a respiration independent second cCTS value using this correction. The corrected cCRS was compared with cCRS values experimentally obtained during CB.

Results

Cardiac chemoreflex sensitivity under free and controlled breathing

Conclusions

Our results suggest that ventilation causes a major disturbance in the measurement of cardiac chemoreflex sensitivity. We argue that this disturbance should be minimised to obtain correct values of cardiac chemoreflex sensitivity for predicting serious arrhythmic events.

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