Chronic obstructive pulmonary disease severity and its association with obstructive sleep apnea syndrome: impact on cardiac autonomic modulation and functional capacity

Katiany Thays Lopes Zangrando,1 Renata Trimer,2 Luiz Carlos Soares de Carvalho Jr,1 Guilherme Peixoto Tinoco Arêas,1 Flávia Cristina Rossi Caruso,1 Ramona Cabiddu,1 Meliza Goi Roscani,3 Fabíola Paula Galhardo Rizzatti,3 Audrey Borghi-Silva1 1Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of São Carlos, São Carlos, São Paulo, Brazil; 2Physical Education and Health Department, University of Santa Cruz do Sul, Santa Cruz do Sul, Rio Grande do Sul, Brazil; 3Medicine Department, Federal University of São Carlos, São Carlos, São Paulo, Brazil Background: The study was conducted to determine the impact of chronic obstructive pulmonary disease (COPD) in association with obstructive sleep apnea syndrome (OSAS) on cardiac autonomic control and functional capacity. Subjects and methods: The study was a cross-sectional prospective controlled clinical study. Heart rate variability indices of 24 COPD (n = 12) and COPD+OSAS (n = 12) patients were evaluated and compared by electrocardiographic recordings acquired during rest, active postural maneuver (APM), respiratory sinus arrhythmia maneuver (RSA-m), and the 6-minute walk test (6MWT). Results: The COPD group presented higher parasympathetic modulation during APM when compared to the COPD+OSAS group (P = 0.02). The COPD+OSAS group presented higher sympathetic modulation during RSA-m when compared to the COPD group (P = 0.00). The performance during 6MWT was similarly impaired in both groups, despite the greater severity of the COPD group. Conclusion: Subjects with COPD+OSAS present marked sympathetic modulation, and the presence of OSAS in COPD subjects has a negative impact on functional capacity regardless of the severity of lung disease. Keywords: COPD, OSAS, COPD+OSAS, functional capacit

COPD assessment test and FEV1: do they predict oxygen uptake in COPD?

Luiz Carlos S Carvalho-Jr,1 Renata Trimer,2 Guilherme PT Arêas,1,3 Flávia CR Caruso,1 Katiany TL Zangrando,1 Soraia Pilon Jürgensen,1 José C Bonjorno Jr,4 Cláudio Ricardo de Oliveira,4 Ramona Cabiddu,1 Renata G Mendes,1 Audrey Borghi-Silva1 1Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of São Carlos, São Carlos, São Paulo, Brazil; 2Physical Education and Health Department, University of Santa Cruz do Sul, Santa Cruz do Sul, Rio Grande do Sul, Brazil; 3Department of Physiology Science, Federal University of Amazonas, Manaus, Amazonas, Brazil; 4Department of Medicine, Federal University of São Carlos, São Carlos, São Paulo, Brazil Background: Chronic obstructive pulmonary disease (COPD) manifests itself in complex ways, with local and systemic effects; because of this, a multifactorial approach is needed for disease evaluation, in order to understand its severity and impact on each individual. Thus, our objective was to study the correlation between easily accessible variables, usually available in clinical practice, and maximum aerobic capacity, and to determine models for peak oxygen uptake (VO2peak) estimation in COPD patients.Subjects and methods: Individuals with COPD were selected for the study. At the first visit, clinical evaluation was performed. During the second visit, the volunteers were subjected to the cardiopulmonary exercise test. To determine the correlation coefficient of VO2peak with forced expiratory volume in 1 second (FEV1) (% pred.) and the COPD Assessment Test score (CATs), Pearson or Spearman tests were performed. VO2 at the peak of the exercise was estimated from the clinical variables by simple and multiple linear regression analyses.Results: A total of 249 subjects were selected, 27 of whom were included after screening (gender: 21M/5F; age: 65.0±7.3 years; body mass index: 26.6±5.0 kg/m2; FEV1 (% pred.): 56.4±15.7, CAT: 12.4±7.4). Mean VO2peak was 12.8±3.0 mL·kg-1·min-1 and VO2peak (% pred.) was 62.1%±14.9%. VO2peak presented a strong positive correlation with FEV1 (% pred.), r: 0.70, and a moderate negative correlation with the CATs, r: -0.54. In the VO2peak estimation model based on the CAT (estimated VO2peak =15.148- [0.185× CATs]), the index explained 20% of the variance, with estimated error of 2.826 mL·kg-1·min-1. In the VO2peak estimation model based on FEV1 (estimated VO2peak =6.490+ [0.113× FEV1]), the variable explained 50% of the variance, with an estimated error of 2.231 mL·kg-1·min-1. In the VO2peak estimation model based on CATs and FEV1 (estimated VO2peak =8.441- [0.0999× CAT] + [0.1000× FEV1]), the variables explained 55% of the variance, with an estimated error of 2.156 mL·kg-1·min-1.Conclusion: COPD patients’ maximum aerobic capacity has a significant correlation with easily accessible and widely used clinical variables, such as the CATs and FEV1, which can be used to estimate peak VO2. Keywords: chronic obstructive pulmonary disease, exercise, oxygen uptake, symptom