Periodic breathing in heart failure patients: testing the hypothesis of instability of the chemoreflex loop

Abstract

In this study, we applied time- and frequency-domain signal processing techniques to the analysis of respiratory and arterial O(2) saturation (Sa(O(2))) oscillations during nonapneic periodic breathing (PB) in 37 supine awake chronic heart failure patients. O(2) was administered to eight of them at 3 l/min. Instantaneous tidal volume and instantaneous minute ventilation (IMV) signals were obtained from the lung volume signal. The main objectives were to verify 1) whether the timing relationship between IMV and Sa(O(2)) was consistent with modeling predictions derived from the instability hypothesis of PB and 2) whether O(2) administration, by decreasing loop gain and increasing O(2) stores, would have increased system stability reducing or abolishing the ventilatory oscillation. PB was centered around 0.021 Hz, whereas respiratory rate was centered around 0.33 Hz and was almost stable between hyperventilation and hypopnea. The average phase shift between IMV and Sa(O(2)) at the PB frequency was 205 degrees (95% confidence interval 198-212 degrees). In 12 of 37 patients in whom we measured the pure circulatory delay, the predicted lung-to-ear delay was 28.8 +/- 5.2 s and the corresponding observed delay was 30.9 +/- 8.8 s (P = 0.13). In seven of eight patients, O(2) administration abolished PB (in the eighth patient, Sa(O(2)) did not increase). These results show a remarkable consistency between theoretical expectations derived from the instability hypothesis and experimental observations and clearly indicate that a condition of loss of stability in the chemical feedback control of ventilation might play a determinant role in the genesis of PB in awake chronic heart failure patients.

Correntropy-Based Spectral Characterization of Respiratory Patterns in Patients With Chronic Heart Failure

“…These frequency ranges are in good agreement with those earlier reported by Pinna et al [9]. The flow signals were decimated from 250 to 2 Hz, using null-phase antialiasing filtering, to account for the fact that the frequencies of interest only ranges up to about 0.5 Hz; oversampling is of particular importance to avoid when performing AR spectral analysis [30].…”

“…PB has a prevalence as high as 70% in CHF patients [5], and is associated with increased mortality [6], especially in CSR patients [7], [8]. The breathing patterns are also influenced by wakefulness or sleep, posture, as well as physiological and mental activity [9]. Physiological parameters for the characterization and detection of different breathing patterns have been suggested in a number of recent clinical studies [10], [11].…”

Short-Term Heart Rate Variability Strongly Predicts Sudden Cardiac Death in Chronic Heart Failure Patients

“…In CHF patients, abnormal breathing patterns may play a confounding role that is abolished by controlled respiration 9 or O 2 administration. 19 Moreover, even in the absence of a sustained abnormal breathing pattern, tidal volume in CHF patients is often quite irregular, thus affecting HRV assessment. Our data show that a simple bedside ECG recording of Ͻ10 minutes' duration obtained during controlled breathing provides additional important prognostic information.…”

Modeling Alveolar Volume Changes During Periodic Breathing in Heterogeneously Ventilated Lungs

“…Above 104 mmHg, oxygen levels are defined as healthy, 10 and this function ensures that ventilation increases only in response to a low blood oxygen level by the definition For a suitable choice of parameters, the Reduced Model exhibits regular oscillations in F A 1 ; P aO 2 and _ V; which are in agreement with some experimental data. 9,19,20 However, one weakness of this work is revealed in the shape of the oscillations of the ventilation function, which are regular and indicate that a subject alternates between light and deep breathing with equal duration. As outlined earlier, this is not the case for a subject suffering from periodic breathing, which is characterized by short bursts of high ventilation interspersed with longer periods of low ventilation.…”

“…However, periodicities in arterial blood oxygen concentration have been observed in subjects exhibiting periodic breathing, which are uniformly associated with low arterial oxygen partial pressure. 9,19,20 Whiteley et al 24 investigate the chemosensory response to oxygen signals and the subsequent effect on ventilation under such conditions. Mismatch between inspired ventilation and perfusion inside the lungs, often the consequence of respiratory illness, leads to inhomogeneity in the transfer of gas and low arterial blood oxygen partial pressure.…”