<p>In order to examine the usefulness of the multi breath helium dilution method (MB) it was compared to the single breath helium dilution method (SB) and body plethysmography (BP). Residual volume (RV), total lung capacity (TLC) and vital capacity (VC) were measured in seventeen subjects with obstructive (11) or restrictive (6) lung disease and four normal subjects.</p><p>With information from professional literature and current periodicals, advantages and disadvantages with all three methods were compared. ANOVA and Student's t-test were performed on the measurement results.</p><p>The results of the statistical tests tell us there are differences among the methods in the group of obstructive patients. They also reveal a notable difference between the MB and SB methods when measuring the same parameter. In addition, it was noted that none of the existing sets of prediction equations fulfill the requirements established on high quality lung function testing.</p><p>Although a thorough evaluation of the reproducibility of the method is still required, it appears to be a viable alternative to body plethysmography. We claim that measuring the above mentioned static lung volumes with only the single breath helium dilution method cannot be considered a satisfactory practice.</p>

In order to examine the usefulness of the multi breath helium dilution method (MB) it was compared to the single breath helium dilution method (SB) and body plethysmography (BP). Residual volume (RV), total lung capacity (TLC) and vital capacity (VC) were measured in seventeen subjects with obstructive (11) or restrictive (6) lung disease and four normal subjects. With information from professional literature and current periodicals, advantages and disadvantages with all three methods were compared. ANOVA and Student's t-test were performed on the measurement results. The results of the statistical tests tell us there are differences among the methods in the group of obstructive patients. They also reveal a notable difference between the MB and SB methods when measuring the same parameter. In addition, it was noted that none of the existing sets of prediction equations fulfill the requirements established on high quality lung function testing. Although a thorough evaluation of the reproducibility of the method is still required, it appears to be a viable alternative to body plethysmography. We claim that measuring the above mentioned static lung volumes with only the single breath helium dilution method cannot be considered a satisfactory practice.

Made available in DSpace on 2016-06-02T20:19:26Z (GMT). No. of bitstreams: 1 6645.pdf: 2027088 bytes, checksum: 18fe5648e0835cf1cfcbef303f079520 (MD5) Previous issue date: 2015-02-27 / Universidade Federal de Sao Carlos / In chronic obstructive pulmonary disease (COPD), functional and structural impairment of lung function can negatively impact heart rate variability (HRV); in addition, a reduced exercise capacity is an important independent prognostic marker in COPD patients. However, 1) if the degree of lung impairment negatively impacts HRV responses and 2) whether the injury of the autonomic control may be associated with reduced exercise capacity in patients with COPD remain unclear. Thus, two studies were conducted in order to verify if functional status at rest and during exercise would be related to autonomic impairment in COPD patients. In the first study, entitled "Relationship between linear and nonlinear dynamics of heart rate and impairment of lung function in COPD patients," we investigated whether the impairment static lung volumes and lung diffusion capacity (DL) would be related to HRV indices in moderate-to-severe COPD. Sixteen patients with COPD underwent pulmonary function tests (spirometry, plethysmography and lung diffusion capacity for carbon monoxide - DLCO). The RR interval was registered in the supine, standing and seated positions and during a respiratory sinus arrhythmia maneuver (M-RSA). Our results suggest that responses of HRV indices were more prominent during M-RSA in moderate-to-severe COPD. Moreover, greater lung function impairment was related to poorer heart rate dynamics. Finally, impaired DLCO is related to an altered parasympathetic response in these patients. The second study, entitled "Are linear and nonlinear heart rate dynamics in submaximal exercise related to cardiorespiratory responses during maximal exercise in patients with COPD?", we inquired whether there is a relationship between HRV responses and exercise capacity in patients with COPD. Fifteen patients underwent incremental cardiopulmonary exercise testing and six-minute walk test (6MWT). The RR interval was registered at rest (standing position) and during 6MWT. Our results showed that HRV responses at rest and during simple field tests may reflect functional impairment of COPD patients, providing important information about both ventilatory and hemodynamic inefficiency in these patients. / Em pacientes com doença pulmonar obstrutiva crônica (DPOC), as alterações funcionais e estruturais do pulmão podem impactar negativamente na variabilidade da frequência cardíaca (VFC). Além disso, a reduzida capacidade de exercício se traduz como um marcador prognóstico nesses pacientes. No entanto, ainda não estão esclarecidos 1) se o grau de comprometimento pulmonar tem impacto negativo sobre as respostas da VFC, frente a diferentes estímulos autonômicos, e 2) se o prejuízo no controle autonômico pode estar relacionado à reduzida capacidade de exercício nos pacientes com DPOC. Sendo assim, dois estudos foram realizados com o intuito de relacionar as alterações funcionais, no repouso e no exercício, com o grau de prejuízo autonômico em pacientes com DPOC. O primeiro estudo, cujo título é Correlação entre as dinâmicas linear e não linear da frequência cardíaca e o comprometimento da função pulmonar em pacientes com DPOC , teve como objetivo investigar se o comprometimento nos volumes pulmonares estáticos e na difusão pulmonar estaria relacionado aos índices da VFC em repouso e em resposta às mudanças posturais. Dezesseis pacientes com diagnóstico de DPOC foram submetidos à prova de função pulmonar (espirometria, pletismografia e capacidade de difusão pulmonar ao monóxido de carbono DCO) e à coleta da VFC nas posturas supino, ortostatismo e sentado e durante a manobra de arritmia sinusal respiratória (M-ASR). Nossos resultados sugerem que as respostas da VFC frente a um estímulo vagal (M-ASR) são mais evidentes. Ainda, quanto maior o comprometimento da função pulmonar pior a dinâmica da frequência cardíaca. Por fim, a redução da DCO está relacionada à alterada resposta vagal nos pacientes com DPOC. O segundo estudo, intitulado Os índices da dinâmica linear e não linear na frequência cardíaca no exercício submáximo estão relacionados com as respostas cardiorrespiratórias ao exercício máximo em pacientes com DPOC? teve por objetivo avaliar se existe relação entre as respostas da VFC e a capacidade de exercício em pacientes com DPOC. Quinze pacientes foram submetidos aos testes de exercício cardiopulmonar incremental e de caminhada de seis minutos (TC6). A coleta da VFC feita em repouso (ortostatismo) e durante o TC6. Os resultados mostraram que as respostas da VFC no repouso e em testes simples de campo podem inferir o prejuízo funcional de pacientes com DPOC, fornecendo informações importantes acerca das limitações ventilatória e hemodinâmica destes pacientes.