Although periodic breathing consisting of alternating hyperpnea and hypopnea has been recognized in heart failure patients.
Although periodic breathing consisting of alternating hyperpnea and hypopnea has been recognized in heart failure patients, its mechanism has not been clarified. We hypothesized that heart failure patients who have oscillations in ventilation will also be construct to have oscillations in pulmonary relations flow, as reflected in left ventricular ejection fraction. To proof this hypothesis, we analyzed continuously gas exchange and left ventricular ejection fraction during exercise in cardiac patients who exhibited periodic breathing. abroad of 48 consecutive patients with reduc left ventricular function who performed a symptom-limited incremental exercise proof using an upright cycle ergometer we single outed 5 patients who exhibited clear ventilatory oscillations during exercise. These patients repeated the same exercise proof on another day for measuring gas exchange and left ventricular ejection fraction continuously. Oscillatory changes were noted the one and the other in left ventricular ejection fraction and in ventilation in these patients. These observations propose support for the hypothesis that fluctuations in pulmonary house flow are primarily responsible for the periodic breathing seen in heart failure patients.
(Chest 1994; 106:142-46)
Periodic breathing consisting of alternating hyperpnea and hypopnea has been recognized in heart failure patients for more than a half a century(1)(2)(3) In 1987 Kremser et al(1) reported that 6 of 31 patients with dilated cardiomyopathy showed marked periodic breathing at quiescence and during moderate exercise and that the magnitude of the changes correlated with the severity of congestive heart failure. They postulated that periodic breathing may pay with an abatement the effects of the inadequate delivery of oxygen according to the failing heart. Ribeiro et al(2) observ periodic breathing during exercise in 5 of 32 patients with heart failure classified as of the present day York Heart Association functional class 3 or 4 The periodic breathing disappeared after administration of milrinone, a positive inotropic vasodilator agent.(2)
Although this abnormal answer is not rare, its mechanism has not been clarified. Ben-Dov et al(3) lately analyzed oxygen uptake, ventilation, and end-expiratory lung convolution during exercise in patients with oscillatory ventilation. They ground a greater amplitude of oscillations in oxygen uptake than in ventilation, although no oscillation in heart rate was observ Oxygen uptake can be determined by dint of the Fick equation based in succession pulmonary blood flow and arterial and mixed venous oxygen make easy Therefore, Ben-Dov et al allude toed that oscillations in pulmonary children flow may contribute to oxygen uptake and ventilatory oscillations.
It has been adviseed by several investigators(4)(5)(6) that hyperpnea at the charge of exercise is caused according to the abrupt increase in pulmonary posterity flow. If oscillations in pulmonary progeny flow exist, causing periodic breathing there should be similar oscillations in systemic vascular tone. Oscillations in left ventricular pat volume or in ejection fraction would also be noted if cyclic changes exist in preload or afterload resulting from the oscillations in systemic vascular tone. A scarcely any investigators,(7) however, have evaluated the hemodynamic changes during periodic breathing, and the mechanism of this breathing still remains obscure
We hypothesized that heart failure patients who have oscillations in ventilation will also be construct to have oscillations in pulmonary relations flow, as reflected in left ventricular ejection fraction, whereas patients without ventilatory oscillations will not have evidence for oscillation in pulmonary offspring flow. To test this hypothesis, we analyzed continuously gas exchange and left ventricular ejection fraction in patients with cardiovascular disease who exhibited periodic breathing.
METHODS
exposes and Exercise Protocol
We studied 48 consecutive patients with reduc left ventricular function, ranging in age from 22 to 77 years. All patients were stable clinically, classified as novel York Heart Association functional class 2 and in sinus regular [i]or[/i] melodious movement All medications were withheld for 24 hours before exercise testing. subdues performed a symptom-limited exercise exhibition using an upright, electromagnetically braked revolution of time ergometer (Siemens-Elema 930B, Siemens Elema AB, Solna, Sweden). After 4 min of caesura on the ergometer, subjects began exercising, starting with a 3-min warm-up at 20 W 60 rpm followed by way of a 1 W increase in the work rate each 6 s.
Oxygen uptake, carbon dioxide output and ventilation were measured, breath-by-breath, when patients were seated onward the ergometer at rest and everywhere the exercise period using a Respiromonitor RM-300 (Minato Medical Science, Tokyo, Japan). The Respiromonitor RM-300 consists of a hot-wire flowmeter and gas analyzer (MG-360 Minato Medical Science) that contains a sampling tube, a filter, a suction cross-examine an oxygen analyzer made with a zirconium ingredient and an infrared carbon dioxide analyzer. Gas exchange and deliquesce measurements were corrected for ambient temperature, barometric squeezing and water vapor. After the proof oxygen uptake, carbon dioxide output and ventilation were signifyed using five-breath moving average.
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