Mechanism for Cheyne‐Stokes breathing in CHF

Although many CHF have periodic breathing pattern; but mechanism remains challenging. Oscillation of PCO2 in arterial blood confirmed and PCO2/t was a breathing control factor. METHODS PO2, PCO2 and flow were measured at mouth using 200Hz database; then based on dead space volume and FRC to calculate alveolar partial pressure oscillations of O2 and CO2 (same as blood). The SV, LVEDV and EF in normal and CHF, were used to calculate the magnitudes of arterial PO2 and PCO2 oscillation. RESULTS Calculated magnitudes of oscillation PO2 and PCO2 in alveolar were ~7mmHg. Using normal SV, LVEDV and EF were 80ml/beat, 120ml and 75%; and 5:1 for ratio of heart rate to breathe, calculated magnitudes were ~5mmHg in arterial blood. But using CHF's SV(40ml/beat), LVEDV(200ml) and EF(20%), the magnitudes decreased to <2mmHg in arterial blood. The poorer heart function the weaker signal (magnitude). The breath‐by‐breath reduced trend results hypoventilation and/or apnea. While hypoventilation and/or apnea resulting PO2 goes down and/or PCO2 goes up to the threshold level, warning signal will generate a larger breath (hyperventilation) and then breath will become smaller breath‐by‐breath. So CHF will have periodic breathing pattern. CONCLUSIONS Breathing lung generated O2 and CO2 oscillations magnitude decreased in arterial blood by poor heart function is mechanism of periodic breathing in CHF.