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

• Published in: Journal of applied physiology (1985) Vol. 89; no. 6; pp. 2147 - 2157
• Main Authors: Pinna, G. D, Maestri, R, Mortara, A, Rovere, M. T. La, Fanfulla, F, Sleight, P
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.12.2000; American Physiological Society
• Subjects: Arteries; Biological and medical sciences; Cardiac Output, Low - physiopathology; Cardiology. Vascular system; Chronic Disease; Female; Forecasting; Heart; Heart failure; Heart failure, cardiogenic pulmonary edema, cardiac enlargement; Humans; Hypotheses; Male; Medical sciences; Middle Aged; Models, Biological; Oscillometry; Oxygen - blood; Oxygen - pharmacology; Periodicity; Respiration - drug effects; Respiratory system; Spectrum analysis; Time Factors; Human; Heart failure; Chemoreflex; Heart disease; Cardiovascular disease; Pulmonary ventilation; Respiration; Respiratory control; Respiratory system; Chemoreceptor
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.89.6.2147

Departments of 1  Biomedical Engineering, 2  Cardiology, and 3  Pneumology, Fondazione S. Maugeri, Clinica del Lavoro e della Riabilitazione, IRCCS, Istituto Scientifico di Montescano, 27040 Montescano (PV), Italy; and 4  Cardiovascular Medicine, John Radcliffe Hospital, Oxford OX39DU, United Kingdom 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° (95% confidence interval 198-212°). 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. respiratory control; spectral analysis; ventilatory oscillations; O 2 administration; chemoreceptors