Contribution of the Lung to the Genesis of Cheyne‐Stokes Respiration in Heart Failure: Plant Gain Beyond Chemoreflex Gain and Circulation Time

Abstract

Background The contribution of the lung or the plant gain ( PG ; ie, change in blood gases per unit change in ventilation) to Cheyne‐Stokes respiration ( CSR ) in heart failure has only been hypothesized by mathematical models, but never been directly evaluated. Methods and Results Twenty patients with systolic heart failure (age, 72.4±6.4 years; left ventricular ejection fraction, 31.5±5.8%), 10 with relevant CSR (24‐hour apnea‐hypopnea index [ AHI ] ≥10 events/h) and 10 without ( AHI <10 events/h) at 24‐hour cardiorespiratory monitoring underwent evaluation of chemoreflex gain (CG) to hypoxia ( ) and hypercapnia ( ) by rebreathing technique, lung‐to‐finger circulation time, and PG assessment through a visual system. PG test was feasible and reproducible (intraclass correlation coefficient, 0.98; 95% CI , 0.91–0.99); the best‐fitting curve to express the PG was a hyperbola ( R 2 ≥0.98). Patients with CSR showed increased PG , (but not ), and lung‐to‐finger circulation time, compared with patients without CSR (all P <0.05). PG was the only predictor of the daytime AHI ( R =0.56, P =0.01) and together with the also predicted the nighttime AHI ( R =0.81, P =0.0003) and the 24‐hour AHI ( R =0.71, P =0.001). Lung‐to‐finger circulation time was the only predictor of CSR cycle length ( R =0.82, P =0.00006). Conclusions PG is a powerful contributor of CSR and should be evaluated together with the CG and circulation time to individualize treatments aimed at stabilizing breathing in heart failure.