Priscila A. Sperandio

Physiological and clinical relevance of exercise ventilatory efficiency in COPD

Exercise ventilation (V′E) relative to carbon dioxide output (V′CO2) is particularly relevant to patients limited by the respiratory system, e.g. those with chronic obstructive pulmonary disease (COPD). High V′E−V′CO2 (poor ventilatory efficiency) has been found to be a key physiological abnormality in symptomatic patients with largely preserved forced expiratory volume in 1 s (FEV1). Establishing an association between high V′E−V′CO2 and exertional dyspnoea in mild COPD provides evidence that exercise intolerance is not a mere consequence of detraining. As the disease evolves, poor ventilatory efficiency might help explaining “out-of-proportion” breathlessness (to FEV1 impairment). Regardless, disease severity, cardiocirculatory co-morbidities such as heart failure and pulmonary hypertension have been found to increase V′E−V′CO2. In fact, a high V′E−V′CO2 has been found to be a powerful predictor of poor outcome in lung resection surgery. Moreover, a high V′E−V′CO2 has added value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of COPD severity. Documenting improved ventilatory efficiency after lung transplantation and lung volume reduction surgery provides objective evidence of treatment efficacy. Considering the usefulness of exercise ventilatory efficiency in different clinical scenarios, the V′E−V′CO2 relationship should be valued in the interpretation of cardiopulmonary exercise tests in patients with mild-to-end-stage COPD. Ventilatory efficiency is a key measurement for the interpretation of cardiopulmonary exercise testing in COPD http://ow.ly/1nsY307pbz8

Effects of heart failure on cerebral blood flow in COPD: Rest and exercise

Cerebral blood flow (CBF) and oxygenation (COx) are generally well-preserved in COPD. It is unknown whether prevalent cardiovascular co-morbidities, such as heart failure, may impair CBF and COx responses to exertion. Eighteen males with moderate-to-severe COPD (8 with and 10 without overlapping heart failure) underwent a progressive exercise test with pre-frontal CBF and COx measurements (indocyanine green and near-infrared spectroscopy). Mean arterial pressure and cardiac output were lower from rest to exercise in overlap. Only COPD patients demonstrated an increase in arterialized PCO2 towards the end of progressive exercise. CBF index was consistently higher and increased further by ∼40% during exercise in COPD whereas a ∼10% reduction was observed in overlap. COx was lower in overlap despite preserved arterial oxygenation. In conclusion, heart failure introduces pronounced negative effects on CBF and COx in COPD which may be associated with clinically relevant outcomes, including dyspnea, exercise intolerance, cerebrovascular disease and cognitive impairment.

Exercise Ventilation in COPD: Influence of Systolic Heart Failure

ABSTRACT Systolic heart failure is a common and disabling co-morbidity of chronic obstructive pulmonary disease (COPD) which may increase exercise ventilation due to heightened neural drive and/or impaired pulmonary gas exchange efficiency. The influence of heart failure on exercise ventilation, however, remains poorly characterized in COPD. In a prospective study, 98 patients with moderate to very severe COPD [41 with coexisting heart failure; ‘overlap’ (left ventricular ejection fraction < 50%)] underwent an incremental cardiopulmonary exercise test (CPET). Compared to COPD, overlap had lower peak exercise capacity despite higher FEV1. Overlap showed lower operating lung volumes, greater ventilatory inefficiency and larger decrements in end-tidal CO2 (PETCO2) (P < 0.05). These results were consistent with those found in FEV1-matched patients. Larger areas under receiver operating characteristic curves to discriminate overlap from COPD were found for ventilation (E)-CO2 output CO2) intercept, E-CO2 slope, peak E/CO2 ratio and peak PETCO2. Multiple logistic regression analysis revealed that CO2 intercept ≤ 3.5 L/minute [odds ratios (95% CI) = 7.69 (2.61–22.65), P < 0.001] plus E-CO2 slope ≥ 34 [2.18 (0.73–6.50), P = 0.14] or peak E/CO2 ratio ≥ 37 [5.35 (1.96–14.59), P = 0.001] plus peak PETCO2 ≤ 31 mmHg [5.73 (1.42–23.15), P = 0.01] were indicative of overlapping. Heart failure increases the ventilatory response to metabolic demand in COPD. Variables reflecting excessive ventilation might prove useful to assist clinical interpretation of CPET responses in COPD patients presenting heart failure as co-morbidity.

Does Exercise Ventilatory Inefficiency Predict Poor Outcome in Heart Failure Patients With COPD

PURPOSE: To investigate whether the opposite effects of heart failure (HF) and chronic obstructive pulmonary disease (COPD) on exercise ventilatory inefficiency (minute ventilation [ E]-carbon dioxide output [ CO2] relationship) would negatively impact its prognostic relevance. METHODS: After treatment optimization and an incremental cardiopulmonary exercise test, 30 male patients with HF-COPD (forced expiratory volume in 1 second [FEV1] = 57% ± 17% predicted, ejection fraction = 35% ± 6%) were prospectively followed up during 412 ± 261 days for major cardiac events. RESULTS: Fourteen patients (46%) had a negative outcome. Patients who had an event had lower echocardiographically determined right ventricular fractional area change (RVFAC), greater ventilatory inefficiency (higher E/ CO2 nadir), and lower end-tidal CO2 (PETCO2) (all P < .05). Multivariate Cox models revealed that E/ CO2 nadir >36, &Dgr;PETCO2(PEAK-REST)≥2 mm Hg, and PETCO2PEAK⩽33 mm Hg added prognostic value to RVFAC⩽45%. Kaplan-Meyer analyses showed that although 18% of patients with RVFAC>45% had a major cardiac event after 1 year, no patient with RVFAC>45% and E/ CO2 nadir ⩽36 (or PETCO2PEAK>33 mm Hg) had a negative event. Conversely, although 69% of patients with RVFAC⩽45% had a major cardiac event after 1 year, all patients with RVFAC⩽45% and &Dgr;PETCO2(PEAK-REST)≥2 mm Hg had a negative event. CONCLUSION: Ventilatory inefficiency remains a powerful prognostic marker in HF despite the presence of mechanical ventilatory constraints induced by COPD. If these preliminary findings are confirmed in larger studies, optimal thresholds for outcome prediction are likely greater than those traditionally recommended for HF patients without COPD.

Influência da insuficiência cardíaca nos volumes pulmonares de repouso em pacientes com DPOC

Objetivo: Avaliar a influência da insuficiência cardíaca crônica (ICC) nos volumes pulmonares de repouso em pacientes com DPOC, ou seja, fração inspiratória — capacidade inspiratória (CI)/CPT — e reserva inspiratória relativa — [1 − (volume pulmonar inspiratório final/CPT)]. Métodos: Após cuidadosa estabilização clínica, 56 pacientes com DPOC (24 alocados no grupo DPOC+ICC; 23 homens/1 mulher) e 32 (28 homens/4 mulheres) com DPOC isolada foram submetidos à espirometria forçada e lenta e pletismografia de corpo inteiro. Resultados: Os pacientes do grupo DPOC+ICC apresentaram maior VEF1, VEF1/CVF e VEF1/capacidade vital lenta; porém, todos os principais volumes “estáticos” — VR, capacidade residual funcional (CRF) e CPT — foram menores que aqueles do grupo DPOC (p < 0,05). A CRF diminuiu mais do que o VR, determinando assim menor volume de reserva expiratória no grupo DPOC+ICC que no grupo DPOC. Houve redução relativamente proporcional da CRF e da CPT nos dois grupos; logo, a CI também foi similar. Consequentemente, a fração inspiratória no grupo DPOC+ICC foi maior que no grupo DPOC (0,42 ± 0,10 vs. 0,36 ± 0,10; p < 0,05). Embora a razão volume corrente/CI fosse maior no grupo DPOC+ICC, a reserva inspiratória relativa foi notadamente similar entre os grupos (0,35 ± 0,09 vs. 0,44 ± 0,14; p < 0,05). Conclusões: Apesar dos efeitos restritivos da ICC, pacientes com DPOC+ICC apresentam elevações relativas dos limites inspiratórios (maior fração inspiratória). Entretanto, esses pacientes utilizam apenas parte desses limites, com o provável intuito de evitar reduções críticas da reserva inspiratória e maior trabalho elástico.

Pulmonary artery wedge pressure and exercise oscillatory ventilation in pre-capillary pulmonary hypertension.

a Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department ofMedicine, School ofMedicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil b Pulmonary Vascular Group, Respiratory Division, Department of Medicine, School of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil c Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queens University, Kingston, Canada d Respiratory Investigation Unit (RIU), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queens University, Kingston, Canada

Alternatives to Aerobic Exercise Prescription in Patients with Chronic Heart Failure

Background Exercise is essential for patients with heart failure as it leads to a reduction in morbidity and mortality as well as improved functional capacity and oxygen uptake (⩒O2). However, the need for an experienced physiologist and the cost of the exam may render the cardiopulmonary exercise test (CPET) unfeasible. Thus, the six-minute walk test (6MWT) and step test (ST) may be alternatives for exercise prescription. Objective The aim was to correlate heart rate (HR) during the 6MWT and ST with HR at the anaerobic threshold (HRAT) and peak HR (HRP) obtained on the CPET. Methods Eighty-three patients (58 ± 11 years) with heart failure (NYHA class II) were included and all subjects had optimized medication for at least 3 months. Evaluations involved CPET (⩒O2, HRAT, HRP), 6MWT (HR6MWT) and ST (HRST). Results The participants exhibited severe ventricular dysfunction (ejection fraction: 31 ± 7%) and low peak ⩒O2 (15.2 ± 3.1 mL.kg-1.min-1). HRP (113 ± 19 bpm) was higher than HRAT (92 ± 14 bpm; p < 0.05) and HR6MWT (94 ± 13 bpm; p < 0.05). No significant difference was found between HRP and HRST. Moreover, a strong correlation was found between HRAT and HR6MWT (r = 0.81; p < 0.0001), and between HRP and HRST (r = 0.89; p < 0.0001). Conclusion These findings suggest that, in the absence of CPET, exercise prescription can be performed by use of 6MWT and ST, based on HR6MWT and HRST

Current challenges in managing comorbid heart failure and COPD

ABSTRACT Introduction: Heart failure (HF) with reduced ejection fraction and chronic obstructive pulmonary disease (COPD) frequently coexist, particularly in the elderly. Given their rising prevalence and the contemporary trend to longer life expectancy, overlapping HF–COPD will become a major cause of morbidity and mortality in the next decade. Areas covered: Drawing on current clinical and physiological constructs, the consequences of negative cardiopulmonary interactions on the interpretation of pulmonary function and cardiopulmonary exercise tests in HF–COPD are discussed. Although those interactions may create challenges for the diagnosis and assessment of disease stability, they provide a valuable conceptual framework to rationalize HF–COPD treatment. The impact of COPD or HF on the pharmacological treatment of HF or COPD, respectively, is then comprehensively discussed. Authors finalize by outlining how the non-pharmacological treatment (i.e. rehabilitation and exercise reconditioning) can be tailored to the specific needs of patients with HF–COPD. Expert commentary: Randomized clinical trials testing the efficacy and safety of new medications for HF or COPD should include a sizeable fraction of patients with these coexistent pathologies. Multidisciplinary clinics involving cardiologists and respirologists trained in both diseases (with access to unified cardiorespiratory rehabilitation programs) are paramount to decrease the humanitarian and social burden of HF–COPD.