We hypothesized that increased serial DS upshifts the VE vs. In the present study, we evaluated HF patients and healthy individuals through a progressive workload exercise with different added DS, hoping to mimic at least in part the effects of COPD on ventilation behaviour during exercise. Up to now, only few studies have evaluated the ventilatory behaviour during exercise in patients with coexisting HF and COPD, being patients with comorbidities usually excluded from research trials dedicated to HF or COPD. As a result, the slope of VE vs.VCO 2 relationship might be elevated, normal or even low in patients with COPD and HF, regardless of the presence and of the severity of ventilatory inefficiency. Indeed, HF hyperventilation can be counteracted by the incapacity of increasing tidal volume (VT) and alveolar ventilation, both being distinctive features of VE during exercise in COPD patients.

In patients with COPD and HF, the ventilatory response to exercise is poorly predictable. HF and COPD often coexist with a reported prevalence of COPD in HF patients ranging between 23 and 30% and with a relevant impact on mortality and hospitalization rates. VCO 2 relationship is normal or low, being the slope lower the more pronounced the emphysema profile. In case of severe COPD, the rise of ventilation during exercise is blunted, and consequently the slope of VE vs. In COPD, ventilatory limitation to exercise is defined either as a reduction of ventilatory reserve or as a lowering of inspiratory capacity. VCO 2 relationship is associated with a poor prognosis –.

The relationship between VE and VCO 2 is used to evaluate ventilatory efficiency in HF, as well as in pulmonary arterial hypertension, an increase of the slope of the VE vs. The elevated ventilatory response in HF patients seen before lactic acidosis ensues and the carbon dioxide (CO 2) generated by the lactate is trivial relative to the rate of metabolic CO 2 production (VCO 2). The behaviour of ventilation during exercise in heart failure (HF) and in chronic obstructive pulmonary disease (COPD) patients may differ, being characterized in the former by an out-of-proportion increase of ventilation (VE), which is greater the greater the HF severity and, in the latter, by a normal or excessive increase of ventilation in mild or moderate COPD and a blunted ventilation increase in severe COPD patients –.

Total ventilation formula dead space