Association of oscillatory ventilation during cardiopulmonary test to clinical and functional variables of chronic heart failure patients

Abstract Objective: The aim of this study is to characterize the presence of exercise oscillatory ventilation (EOV) and to relate it with other cardiopulmonary exercise test (CET) responses and clinical variables. Methods: Forty-six male patients (age: 53.1±13.6 years old; left ventricular ejection fraction [LVEF]: 30±8%) with heart failure were recruited to perform a maximal CET and to correlate the CET responses with clinical variables. The EOV was obtained according to Leite et al. criteria and VE/VCO2 > 34 and peak VO2 < 14 ml/kg/min were used to assess patients' severity. Results: The EOV was observed in 16 of 24 patients who performed the CET, as well as VE/VCO2 > 34 and peak VO2 < 14 ml/kg/min in 14 and 10 patients, respectively. There was no difference in clinical and CET variables of the patients who presented EOV in CET when compared to non-EOV patients. Also, there was no difference in CET and clinical variables when comparing patients who presented EOV and had a VE/VCO2 slope > 34 to patients who just had one of these responses either. Conclusion: The present study showed that there was an incidence of patients with EOV and lower peak VO2 and higher VE/VCO2 slope values, but they showed no difference on other prognostic variables. As well, there was no influence of the presence of EOV on other parameters of CET in this population, suggesting that this variable may be an independent marker of worst prognosis in HF patients.

Microvascular oxygen extraction during maximal isometric contraction in patients with chronic obstructive pulmonary disease / Extração microvascular de oxigênio durante contração isométrica máxima em pacientes com DPOC não hipoxêmicos

Abstract Introduction: COPD presents decrease in oxidative metabolism with possible losses of cardiovascular adjustments, suggesting slow kinetics microvascular oxygen during intense exercise. Objective: To test the hypothesis that chronic obstructive pulmonary disease (COPD) patients have lower muscle performance in physical exercise not dependent on central factors, but also greater muscle oxygen extraction, regardless of muscle mass. Methods: Cross-sectional study with 11 COPD patients and nine healthy subjects, male, paired for age. Spirometry and body composition by DEXA were evaluated. Muscular performance was assessed by maximal voluntary isometric contraction (MVIC) in isokinetic dynamometer and muscle oxygen extraction by the NIRS technique. Student t-test and Pearson correlation were applied. A significance level of p<0.05 was adopted. Results: Patients had moderate to severe COPD (FEV1 = 44.5 ± 9.6% predicted; SpO2 = 94.6 ± 1.6%). Lean leg mass was 8.3 ± 0.9 vs. 8.9 ± 1.0 kg (p =0.033), when comparing COPD and control patients, respectively. The decreased muscle oxygen saturation corrected by muscle mass was 53.2% higher (p=0.044) in the COPD group in MVIC-1 and 149.6% higher (p=0.006) in the MVIC-2. Microvascular extraction rate of oxygen corrected by muscle mass and total work was found to be 114.5% higher (p=0.043) in the COPD group in MVIC-1 and 210.5% higher (p=0.015) in the MVIC-2. Conclusion: COPD patients have low muscle performance and high oxygen extraction per muscle mass unit and per unit of work. The high oxygen extraction suggests that quantitative and qualitative mechanisms can be determinants of muscle performance in patients with COPD.

Resumo Introdução: DPOC (doença pulmonar obstrutiva crônica) apresenta diminuição no metabolismo oxidativo com prejuízos dos ajustes cardiovasculares, sugerindo cinética de oxigênio microvascular lenta durante exercício intenso. Objetivo: Testar hipótese que pacientes com DPOC apresentam não só menor performance muscular em exercício físico não dependente dos fatores centrais, mas também maior extração muscular de O2 independentemente da massa muscular. Métodos: Estudo transversal, 11 pacientes DPOC e 9 indivíduos saudáveis, gênero masculino, pareados pela idade. Avaliado espirometria, composição corporal, performance muscular por contração isométrica voluntária máxima (CIVM) em dinamometria isocinética e extração muscular de oxigênio pela técnica de NIRS. Teste t-Student e correlação de Pearson foram aplicados. Adotado p<0,05 como nível de significância. Resultados: Pacientes com DPOC moderado para grave (VEF1 = 44,5 ± 9,6 % predito; SpO2 = 94,6 ± 1,6 %). Massa magra do membro inferior foi de 8,3 ± 0,9 vs. 8,9 ± 1,0 Kg (p= ,033), comparando DPOC e controle respectivamente. A redução saturação muscular de O2 corrigido pela massa muscular foi 53,2 % maior (p=0,044) no grupo DPOC na CIVM-1 e 149,6% maior (p=0,006) na CIVM-2. A taxa de extração microvascular de O2 corrigida pela massa muscular e trabalho total apresentou-se 114,5% maior (p=0,043) no grupo DPOC na CIVM-1 e 210,5% maior (p= 0,015) na CIVM-2. Conclusão: Pacientes com DPOC apresentam baixa performance muscular e alta extração de O2 por unidade de massa muscular e por unidade de trabalho. A elevada extração de O2 sugere que mecanismos quantitativos e qualitativos podem ser determinantes da performance muscular em pacientes com DPOC.

Influence of heart failure on resting lung volumes in patients with COPD / Influência da insuficiência cardíaca nos volumes pulmonares de repouso em pacientes com DPOC

ABSTRACT Objective: To evaluate the influence of chronic heart failure (CHF) on resting lung volumes in patients with COPD, i.e., inspiratory fraction-inspiratory capacity (IC)/TLC-and relative inspiratory reserve-[1 − (end-inspiratory lung volume/TLC)]. Methods: This was a prospective study involving 56 patients with COPD-24 (23 males/1 female) with COPD+CHF and 32 (28 males/4 females) with COPD only-who, after careful clinical stabilization, underwent spirometry (with forced and slow maneuvers) and whole-body plethysmography. Results: Although FEV1, as well as the FEV1/FVC and FEV1/slow vital capacity ratios, were higher in the COPD+CHF group than in the COPD group, all major "static" volumes-RV, functional residual capacity (FRC), and TLC-were lower in the former group (p < 0.05). There was a greater reduction in FRC than in RV, resulting in the expiratory reserve volume being lower in the COPD+CHF group than in the COPD group. There were relatively proportional reductions in FRC and TLC in the two groups; therefore, IC was also comparable. Consequently, the inspiratory fraction was higher in the COPD+CHF group than in the COPD group (0.42 ± 0.10 vs. 0.36 ± 0.10; p < 0.05). Although the tidal volume/IC ratio was higher in the COPD+CHF group, the relative inspiratory reserve was remarkably similar between the two groups (0.35 ± 0.09 vs. 0.44 ± 0.14; p < 0.05). Conclusions: Despite the restrictive effects of CHF, patients with COPD+CHF have relatively higher inspiratory limits (a greater inspiratory fraction). However, those patients use only a part of those limits, probably in order to avoid critical reductions in inspiratory reserve and increases in elastic recoil.

RESUMO 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.

Can bronchodilators improve exercise tolerance in COPD patients without dynamic hyperinflation? / Os broncodilatadores podem melhorar a tolerância ao exercício na ausência de hiperinsuflação dinâmica em pacientes com DPOC?

OBJECTIVE: To investigate the modulatory effects that dynamic hyperinflation (DH), defined as a reduction in inspiratory capacity (IC), has on exercise tolerance after bronchodilator in patients with COPD. METHODS: An experimental, randomized study involving 30 COPD patients without severe hypoxemia. At baseline, the patients underwent clinical assessment, spirometry, and incremental cardiopulmonary exercise testing (CPET). On two subsequent visits, the patients were randomized to receive a combination of inhaled fenoterol/ipratropium or placebo. All patients then underwent spirometry and submaximal CPET at constant speed up to the limit of tolerance (Tlim). The patients who showed ΔIC(peak-rest) < 0 were considered to present with DH (DH+). RESULTS: In this sample, 21 patients (70%) had DH. The DH+ patients had higher airflow obstruction and lower Tlim than did the patients without DH (DH-). Despite equivalent improvement in FEV1 after bronchodilator, the DH- group showed higher ΔIC(bronchodilator-placebo) at rest in relation to the DH+ group (p < 0.05). However, this was not found in relation to ΔIC at peak exercise between DH+ and DH- groups (0.19 ± 0.17 L vs. 0.17 ± 0.15 L, p > 0.05). In addition, both groups showed similar improvements in Tlim after bronchodilator (median [interquartile range]: 22% [3-60%] vs. 10% [3-53%]; p > 0.05). CONCLUSIONS: Improvement in TLim was associated with an increase in IC at rest after bronchodilator in HD- patients with COPD. However, even without that improvement, COPD patients can present with greater exercise tolerance after bronchodilator provided that they develop DH during exercise. .

OBJETIVO: Investigar os efeitos moduladores da hiperinsuflação dinâmica (HD), definida pela redução da capacidade inspiratória (CI), na tolerância ao exercício após broncodilatador em pacientes com DPOC. MÉTODOS: Estudo experimental e randomizado com 30 pacientes com DPOC sem hipoxemia grave. Na visita inicial, os pacientes realizaram avaliação clínica, espirometria e teste de exercício cardiopulmonar (TECP) incremental. Em duas visitas subsequentes, os pacientes foram randomizados para receber uma combinação de fenoterol/ipratrópio ou placebo e, em seguida, realizaram espirometria e TECP com velocidade constante até o limite da tolerância (Tlim). Os pacientes com ΔCI(pico-repouso) < 0 foram considerados com HD (HD+). RESULTADOS: Nesta amostra, 21 pacientes (70%) apresentaram HD. Os pacientes HD+ apresentaram maior obstrução ao fluxo aéreo e menor Tlim do que os pacientes sem HD (HD-). Apesar de ganhos equivalentes de VEF1 após broncodilatador, o grupo HD- apresentou maior ΔCI(broncodilatador-placebo) em repouso em relação ao grupo HD+ (p < 0,05). Entretanto, isso não ocorreu com a ΔCI no pico do exercício entre os grupos HD+ e HD- (0,19 ± 0,17 L vs. 0,17 ± 0,15 L; p > 0,05). Similarmente, ambos os grupos apresentaram melhoras equivalentes do Tlim após broncodilatador (mediana [intervalo interquartílico]: 22% [3-60%] e 10% [3-53%]; p > 0,05). CONCLUSÕES: A melhora da CI em repouso após broncodilatador associou-se com ganho de tolerância ao esforço mesmo nos pacientes com DPOC que não apresentem HD. Por outro lado, pacientes sem melhora da CI em repouso ainda podem obter beneficio funcional com o broncodilatador desde que apresentem HD no exercício. .

Comportamento da hiperinsuflação dinâmica em teste em esteira rolante em pacientes com DPOC moderada a grave / Dynamic hyperinflation during treadmill exercise testing in patients with moderate to severe COPD

OBJETIVO: Caracterizar a presença, extensão e padrões de hiperinsuflação dinâmica (HD) durante teste em esteira rolante em pacientes com DPOC moderada a grave. Métodos: Estudo transversal com 30 pacientes não hipoxêmicos (VEF1= 43 ± 14 por cento do previsto) submetidos a teste cardiopulmonar de exercício em esteira rolante em velocidade constante (70-80 por cento da velocidade máxima) até o limite da tolerância (Tlim). Manobras seriadas de capacidade inspiratória (CI) foram utilizadas para avaliação da HD. RESULTADOS: Dos 30 pacientes estudados, 19 (63,3 por cento) apresentaram HD (grupo HD+), que apresentaram maior comprometimento funcional em repouso do que os pacientes sem HD (grupo HD-). Nenhuma das variáveis obtidas relacionou-se com a tolerância ao exercício no grupo HD-, enquanto Tlim, CI e percepção de dispneia ao esforço foram significativamente correlacionados no grupo HD+ (p < 0,05). No grupo HD+, 7 e 12 pacientes, respectivamente, apresentaram padrão progressivo e estável de HD (ΔCI Tlim,2min = -0,28 ± 0,11 L e 0,04 ± 0,10 L; p < 0,01). Pacientes com padrão progressivo de HD apresentaram maior relação percepção de dispneia/Tlim e menor tolerância ao exercício do que aqueles com padrão estável (354 ± 118 s e 465 ± 178 s, respectivamente; p < 0,05). CONCLUSÕES: A HD não é um fenômeno universal durante a caminhada em pacientes com DPOC, mesmo que apresentem obstrução ao fluxo aéreo de graus moderado a acentuado. Nos pacientes que apresentaram HD, um padrão progressivo de HD teve maior repercussão na tolerância ao exercício do que um padrão estável de HD.

OBJECTIVE: To characterize the presence, extent, and patterns of dynamic hyperinflation (DH) during treadmill exercise testing in patients with moderate to severe COPD. METHODS: This was a cross-sectional study involving 30 non-hypoxemic patients (FEV1= 43 ± 14 percent of predicted) who were submitted to a cardiopulmonary exercise test on a treadmill at a constant speed (70-80 percent of maximum speed) to the tolerance limit (Tlim). Serial inspiratory capacity (IC) maneuvers were used in order to assess DH. RESULTS: Of the 30 patients studied, 19 (63.3 percent) presented with DH (DH+ group), having greater pulmonary function impairment at rest than did those without DH (DH- group). None of the variables studied correlated with exercise tolerance in the DH- group, whereas Tlim, IC, and perception of dyspnea during exercise did so correlate in the DH+ group (p < 0.05). In the DH+ group, 7 and 12 patients, respectively, presented with a progressive and a stable pattern of DH (ΔIC Tlim,2min = -0.28 ± 0.11 L vs. 0.04 ± 0.10 L; p < 0.01). Patients with a progressive pattern of DH presented with higher perception of dyspnea/Tlim rate and lower exercise tolerance than did those with a stable pattern (354 ± 118 s and 465 ± 178 s, respectively; p < 0.05). CONCLUSIONS: The presence of DH is not a universal phenomenon during walking in COPD patients, even in those with moderate to severe airflow limitation. In the patients who presented DH, a progressive pattern of DH had a greater impact on exercise tolerance than did a stable pattern of DH.

Neuromuscular electrical stimulation improves exercise tolerance in chronic obstructive pulmonary disease patients with better preserved fat-free mass

BACKGROUND: High-frequency neuromuscular electrical stimulation increases exercise tolerance in patients with advanced chronic obstructive pulmonary disease (COPD patients). However, it is conceivable that its benefits are more prominent in patients with better-preserved peripheral muscle function and structure. OBJECTIVE: To investigate the effects of high-frequency neuromuscular electrical stimulation in COPD patients with better-preserved peripheral muscle function. Design: Prospective and cross-over study. METHODS: Thirty COPD patients were randomly assigned to either home-based, high-frequency neuromuscular electrical stimulation or sham stimulation for six weeks. The training intensity was adjusted according to each subject's tolerance. Fat-free mass, isometric strength, six-minute walking distance and time to exercise intolerance (Tlim) were assessed. RESULTS: Thirteen (46.4 percent) patients responded to high-frequency neuromuscular electrical stimulation; that is, they had a post/pre Δ Tlim >10 percent after stimulation (unimproved after sham stimulation). Responders had a higher baseline fat-free mass and six-minute walking distance than their seventeen (53.6 percent) non-responding counterparts. Responders trained at higher stimulation intensities; their mean amplitude of stimulation during training was significantly related to their fat-free mass (r = 0.65; p<0.01). Logistic regression revealed that fat-free mass was the single independent predictor of Tlim improvement (odds ratio [95 percent CI] = 1.15 [1.04-1.26]; p<0.05). CONCLUSIONS: We conclude that high-frequency neuromuscular electrical stimulation improved the exercise capacity of COPD patients with better-preserved fat-free mass because they tolerated higher training stimulus levels. These data suggest that early training with high-frequency neuromuscular electrical stimulation before tissue wasting begins might enhance exercise tolerance in patients with less advanced COPD.