Significance of Oscillatory Breathing on Cardiopulmonary Exercise Testing in Chronic Heart Failure

Shigeru Makita
2013 Circulation Journal  
Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp the mean V E. 11 But Kato et al 10 took more strict criterion (at least 3 consecutive cycles and the amplitude >40% of the mean V E). The criteria of oscillatory breathing have not been widely accepted. There are some criteria according to authors' decision such as >15% 4 or >30% 6 or minimal average amplitude of ventilatory oscillation of 5 L/min. 3 Despite the clear association between exercise
more » ... cillatory breathing and outcomes in chronic heart failure, there are limited data regarding the mechanistic basis for oscillatory breathing. Ventilation is regulated through the feedback loop between pulmonary gas exchanging capillaries and chemoreceptors in the carotid bodies and the medulla. According to Dhakal et al, ventilatory instability and oscillations may arise from (1) increased circulatory delay, (2) increased chemosensitivity, (3) pulmonary congestion or (4) ergoreflex signaling. 12 In this issue of the Journal, Kato et al found that cardiac patients with more impaired cardiopulmonary dysfunction during exercise, as reflected in the CPX indices, have a longer CL of oscillating V E. 10 This finding supports the hypothesis by Murphy et al that oscillatory breathing is an important surrogate for hemodynamic impairment in patients with heart failure. 13 Heart failure patients with exercise oscillatory ventilation (HF + EOV) demonstrated a greater degree of hemodynamic impairment at rest, as evidenced by higher resting right atrial pressure, pulmonary arterial pressure, and pulmonary capillary wedge pressure and lower cardiac index (CI) compared with heart failure patients without exercise oscillatory ventilation (HF -EOV). Exercise filling pressures were also greater in the HF + EOV group than in the HF -EOV group, and HF + EOV patients had 25% lower cumulative exercise CI compared with HF -EOV patients (P<0.001). In multivariate analysis, exercise CI emerged as the leading predictor of EOV (odds ratio 1.39 for each 1.0 L · min -1 · m -2 decrement in CI, 95% confidence interval 1.14-1.70, P<0.001). 13 It is known that the oscillatory breathing noted at rest sometimes becomes unclear or even disappears during high-intensity exercise. This would also support the hypothesis that the circulation delay is an important factor determining oscillatory breathing, because the circulation time becomes shorter with the increased intensity of exercise as the result of the increase in cardiac output. 10 Exercise oscillatory breathing is a noninvasive, easily recognizable and reproducible submaximal exercise parameter observed during CPX. The prognostic significance of exercise oscillatory breathing and the apparent modifiability of oscillatory breathing with heart failure interventions make oscilla-eriodic breathing, which is a form of irregular breathing characterized by cyclic variation of ventilation at rest and exercise, has been a recognized feature of heart failure for almost 2 centuries. 1 More recently, cyclic fluctuations in minute ventilation during exercise have been called exercise oscillatory ventilation or oscillatory breathing. During incremental exercise, when gas exchange parameters such as V O2, V E and V CO2 are plotted using a moving average, a systemic oscillatory pattern is evident both at rest and at lowlevel exercise. This finding is seen in some patients with left ventricular failure and has features similar to Cheyne-Stokes respiration. The oscillations have a period of approximately 1 min from peak to peak and are greatest at rest and during mild-to-moderate exercise. The rise in V O2 begins first, followed by V CO2, V E, and finally R. 2 Article p 661 Oscillatory breathing have been observed in 20.3-29.7% of patients with chronic heart failure, 3-5 but Sun et al revealed 51% of heart failure patients were identified as oscillatory breathing pattern positive. 6 Oscillatory breathing during exercise has emerged as a potent independent risk factor for adverse prognosis in heart failure that is additive to traditional echocardiographic and neurohumoral markers. 5-7 The combined quantification of aerobic capacity (peak V O2) and ventilatory efficacy (V E-V CO2 slope) and oscillatory breathing appear to provide a more comprehensive insight into pathophysiology, disease severity, and prognosis. 8 For the reasons stated above, cardiopulmonary exercise testing (CPX) is an important component in the prognostic and interventional assessment for cardiac patients. 9 In this issue of the Journal, Kato et al 10 mentioned that the cycle length (CL) of oscillating V E significantly correlates negatively with peak V O2 and positively with the V E-V CO2 slope. The oscillatory change in V O2 was also noted with a similar pattern and similar CL to those of oscillating V E. The CL of oscillating V O2 also significantly correlated with peak V O2 and the V E-V CO2 slope. The phase difference between V O2 and V E correlated negatively with peak V O2 and left ventricular ejection fraction (LVEF), and positively with brain natriuretic peptide (BNP), showing a longer phase difference in patients with a lower peak V O2, lower LVEF and higher BNP. In a previous report, Koike et al defined oscillatory breathing as at least 2 consecutive cycles and the amplitude >30% of P The opinions expressed in this article are not necessarily those of the editors or of the Japanese Circulation Society.
doi:10.1253/circj.cj-13-0074 pmid:23363646 fatcat:rzwfrak2mbhave6eqi3bwyrcc4