Sleep quality and architecture in COPD: the relationship with lung function abnormalities / Qualidade e arquitetura do sono na DPOC: relação com anormalidades da função pulmonar

ABSTRACT Objective: Impaired respiratory mechanics and gas exchange may contribute to sleep disturbance in patients with COPD. We aimed to assess putative associations of different domains of lung function (airflow limitation, lung volumes, and gas exchange efficiency) with polysomnography (PSG)-derived parameters of sleep quality and architecture in COPD. Methods: We retrospectively assessed data from COPD 181 patients ≥ 40 years of age who underwent spirometry, plethysmography, and overnight PSG. Univariate and multivariate linear regression models predicted sleep efficiency (total sleep time/total recording time) and other PSG-derived parameters that reflect sleep quality. Results: The severity of COPD was widely distributed in the sample (post-bronchodilator FEV1 ranging from 25% to 128% of predicted): mild COPD (40.3%), moderate COPD (43.1%), and severe-very severe COPD (16.6%). PSG unveiled a high proportion of obstructive sleep apnea (64.1%) and significant nocturnal desaturation (mean pulse oximetry nadir = 82.2% ± 6.9%). After controlling for age, sex, BMI, apnea-hypopnea index, nocturnal desaturation, comorbidities, and psychotropic drug prescription, FEV1/FVC was associated with sleep efficiency (β = 25.366; R2 = 14%; p < 0.001), whereas DLCO predicted sleep onset latency (β = −0.314; R2 = 13%; p < 0.001) and rapid eye movement sleep time/total sleep time in % (β = 0.085; R2 = 15%; p = 0.001). Conclusions: Pulmonary function variables reflecting severity of airflow and gas exchange impairment, adjusted for some potential confounders, were weakly related to PSG outcomes in COPD patients. The direct contribution of the pathophysiological hallmarks of COPD to objectively measured parameters of sleep quality seems to be less important than it was previously assumed.

RESUMO Objetivo: O comprometimento da mecânica respiratória e das trocas gasosas pode contribuir para distúrbios do sono em pacientes com DPOC. Objetivamos avaliar associações putativas de diferentes domínios da função pulmonar (limitação do fluxo aéreo, volumes pulmonares e eficiência das trocas gasosas) com parâmetros da qualidade e arquitetura do sono na DPOC derivados da polissonografia (PSG). Métodos: Avaliamos retrospectivamente dados de 181 pacientes com DPOC e idade ≥ 40 anos que foram submetidos a espirometria, pletismografia e PSG de noite inteira. Modelos de regressão linear univariada e multivariada foram utilizados para avaliar a associação de variáveis de função pulmonar com a eficiência do sono (tempo total de sono/tempo total de registro) e outros parâmetros derivados da PSG que refletem a qualidade do sono. Resultados: A gravidade da DPOC foi bem distribuída na amostra (VEF1 pós-broncodilatador variando de 25% a 128% do previsto): DPOC leve (40,3%), DPOC moderada (43,1%) e DPOC grave-muito grave (16,6%). A PSG revelou uma alta frequência de apneia obstrutiva do sono (64,1%) e dessaturação noturna significativa (nadir médio da oximetria de pulso = 82,2% ± 6,9%). Após controle para idade, sexo, IMC, índice de apneia-hipopneia, dessaturação noturna, comorbidades e prescrição de psicotrópicos, a relação VEF1/CVF apresentou associação com a eficiência do sono (β = 25,366; R2 = 14%; p < 0,001), enquanto a DLCO previu a latência para o início do sono (β = −0,314; R2 = 13%; p < 0,001) e o tempo de sono rapid eye movement/tempo total de sono em % (β = 0,085; R2 = 15%; p = 0,001). Conclusões: As variáveis de função pulmonar que refletem a gravidade do comprometimento do fluxo aéreo e das trocas gasosas, ajustadas para alguns potenciais fatores de confusão, apresentaram fraca relação com os resultados da PSG nos pacientes com DPOC. A contribuição direta das características fisiopatológicas da DPOC para os parâmetros da qualidade do sono medidos objetivamente parece ser menos importante do que se supunha anteriormente.

Determination of anaerobic threshold through heart rate and near infrared spectroscopy in elderly healthy men

BACKGROUND: Aging leads to low functional capacity and this can be reversed by safe and adequate exercise prescription. OBJECTIVE: The aim of this study was to identify the anaerobic threshold (AT) obtained from the V-slope method as well as visual inspection of oxyhemoglobin ( O2Hb) and deoxyhemoglobin (HHb) curves and compare findings with the heteroscedastic (HS) method applied to carbon dioxide production ( CO2), heart rate (HR), and HHb data in healthy elderly men. A secondary aim was to assess the degree of agreement between methods for AT determination. METHOD: Fourteen healthy men (61.4±6.3 years) underwent cardiopulmonary exercise testing (CPX) on a cycle ergometer until physical exhaustion. Biological signals collected during CPX included: ventilatory and metabolic variables; spectroscopy quasi-infrared rays - NIRS; and HR through a cardio-frequency meter. RESULTS: We observed temporal equivalence and similar values of power (W), absolute oxygen consumption (O2 - mL/min), relative O2 ( mL.Kg - 1.min -1), and HR at AT by the detection methods performed. In addition, by the Bland-Altman plot, HR confirmed good agreement between the methods with biases between -1.3 and 3.5 beats per minute. CONCLUSIONS: (i) all detection methods were sensitive in identifying AT, including the HS applied to HR and (ii) the methods showed a good correlation in the identification of AT. Thus, these results support HR as valid and readily available parameter in determining AT in healthy elderly men. .