Overlap syndrome: the coexistence of OSA further impairs cardiorespiratory fitness in COPD.

BACKGROUND: Cardiorespiratory fitness (CRF) is an important prognostic marker in chronic obstructive pulmonary disease (COPD). Obstructive sleep apnea (OSA) also negatively affects exercise tolerance. However, the impact of their association on CRF has not been evaluated. We hypothesized that patients with overlap syndrome would demonstrate a greater impairment in CRF, particularly those with severe COPD. METHODS: Individuals with COPD were recruited. First, subjects underwent clinical and spirometry evaluation. Next, home-based sleep evaluation was performed. Subjects with an apnea-hypopnea index (AHI) < 15 episodes/h were allocated to the COPD group and those with an AHI ≥ 15 episodes/h to the overlap group. On the second visit, subjects underwent a cardiopulmonary exercise test. Subsequently, they were divided into four groups according to the severity of COPD and coexistence of OSA: COPDI/II; overlap I/II; COPDIII/IV; and overlap III/IV. RESULTS: Of the 268 subjects screened, 31 were included. The overlap group exhibited higher values for peak carbon dioxide (COPD: 830 [678-1157]; overlap: 1127 [938-1305] mm Hg; p < 0.05), minute ventilation (COPD: 31 [27-45]; overlap: 48 [37-55] L; p < 0.05), and peak systolic blood pressure (COPD: 180 [169-191]; overlap: 220 [203-227] mm Hg; p <; 0.001) and peak diastolic blood pressure COPD: 100 [93-103]; overlap: 110 [96-106] mm Hg; p < 0.001). COPD severity associated with OSA produced a negative impact on exercise time (COPDIII/IV: 487 ± 102; overlap III/IV: 421 ± 94 s), peak oxygen uptake (COPDIII/IV: 12 ± 2; overlap III/IV: 9 ± 1 ml.Kg.min-1 ; p < 0.05) and circulatory power (COPDIII/IV: 2306 ± 439; overlap III/IV: 2162 ± 340 ml/kg/min.mmHg; p < 0.05). CONCLUSION: Overlap syndrome causes greater hemodynamic and ventilatory demand at the peak of dynamic exercise. In addition, OSA overlap in individuals with more severe COPD impairs CRF.

Increased parasympathetic cardiac modulation in patients with acute exacerbation of COPD: how should we interpret it?

BACKGROUND: Cardiac autonomic modulation (CAM) is impaired in patients with stable COPD. Exacerbation aggravates the patients' health status and functional capacity. While the clinical and functional effects of exacerbation are known, no studies investigated CAM during exacerbation and whether there is a relationship between CAM and functional capacity and dyspnea. METHODS: Thirty-two patients with moderate to severe COPD were enrolled into two groups: stable COPD (GSta, n=16) and acute exacerbation of COPD (GAE, n=16). The GAE patients were evaluated 24-48 hours after starting standard therapy for COPD exacerbation during hospitalization; the GSta patients were evaluated in an outpatient clinic and included in the study if no decompensation episodes had occurred during the previous month. The heart rate (HR) and R-wave peak detection intervals in ms (RRi) were registered using a heart rate monitor (Polar® system) at rest in seated position during 10 minutes. CAM was assessed by heart rate variability (HRV) linear and non-linear analysis. Functional capacity was evaluated by handgrip strength test, performed by Jamar® dynamometer, and dyspnea was scored using the modified scale of the Medical Research Council. RESULTS: GAE presented higher parasympathetic CAM values compared with GSta for square root of the mean squared differences of successive RRi (RMSSD; 17.8±5.6 ms vs 11.7±9.5 ms); high frequency (HF; 111.3±74.9 ms2 vs 45.6±80.7 ms2) and standard deviation measuring the dispersion of points in the plot perpendicular to the line of identity (SD1; 12.7±3.9 ms vs 8.3±6.7 ms) and higher CAM values for standard deviation of the mean of all of RRi (STD RRi; 19.3±6.5 ms vs 14.3±12.5 ms); RRi tri (5.2±1.7 ms vs 4.0±3.0 ms); triangular interpolation of NN interval histogram (TINN; 88.7±26.9 ms vs 70.6±62.2 ms); low frequency (LF; 203±210.7 ms2 vs 101.8±169.7 ms2) and standard deviation measuring the dispersion of points along the line of identity (SD2; 30.4±14.8 ms vs 16.2±12.54 ms). Lower values were observed for the complexity indices: approximate entropy (ApEn; 0.9±0.07 vs 1.06±0.06) and sample entropy (SampEn; 1.4±0.3 vs 1.7±0.3). Significant and moderate associations were observed between HF (nu) and handgrip strength (r=-0.58; P=0.01) and between LF (ms2) and subjective perception of dyspnea (r=-0.53; P=0.03). CONCLUSION: COPD exacerbated patients have higher parasympathetic CAM than stable patients. This should be interpreted with caution since vagal influence on the airways determines a narrowing and not a better clinical condition. Additionally, functional capacity was negatively associated with parasympathetic CAM in COPD exacerbation.

Função pulmonar e depuração mucociliar nasal de cortadores de cana-de-açúcar brasileiros expostos à queima de biomassa / Lung function and nasal mucociliary clearance in Brazilian sugarcane cutters exposed to biomass burning

Resumo Objetivos: avaliar a função pulmonar e a depuração mucociliar nasal de cortadores de cana-de-açúcar. Métodos: foram avaliados dezesseis cortadores de cana-de-açúcar em dois períodos: durante o plantio da cana-de-açúcar, em abril/2011, e no final da safra, no período de queima e colheita manual da cana-de-açúcar, outubro/2011. A função pulmonar e a depuração mucociliar foram avaliadas por meio da espirometria e do teste de tempo de trânsito da sacarina (TTS), respectivamente. Resultados: a função pulmonar apresentou diminuição no %FEF25-75 [99,31 (23,79) até 86,36 (27,41); p = 0,001]; %VEF1 [92,19 (13,24) até 90,44 (12,76); p = 0,022] e VEF1/CVF [88,62 (5.68) até 84,90 (6.47); p = 0,004] no período da colheita em comparação ao de plantio. Também houve uma diminuição significativa no resultado do teste do TTS na colheita [3 (1) min] em comparação ao plantio [8 (3) min] (p < 0,001). Conclusão: os cortadores de cana-de-açúcar apresentaram diminuição do %FEF25-75, %VEF1, do índice VEF1/CVF, e aumento da velocidade do transporte mucociliar nasal no final do período de colheita.

Abstract Objective: to evaluate the effects of sugarcane burning on lung function and mucociliary clearance in sugarcane workers. Methods: sixteen sugarcane workers were evaluated in two sequential periods: during the non-harvest season, in April/2011, and during the sugarcane burning harvest season, in October/2011. Mean values (standard deviation) of lung function and mucociliary clearance were evaluated through spirometry and the saccharin transit time (STT) test, respectively. Results: lung function decreased %FEF25-75 [99.31 (23.79) to 86.36 (27.41); p = 0.001]; %FEV1 [92.19 (13.24) to 90.44 (12.76); p = 0.022]; and FEV1/FVC [88.62 (5.68) to 84.90 (6.47); p = 0.004] during the harvest season compared with the non-harvest season. A significant decrease was found in saccharin transit time during the harvest [3 (1) min] season compared with the non-harvest season [8 (3) min] (p < 0.001). Conclusion: sugarcane workers present a decrease in %FEF25-75, %FEV1, FEV1/FVC ratio, and increase in nasal mucociliary transport velocity at the end of the harvest season.