A more effective alternative to the 6-minute walk test for the assessment of functional capacity in patients with pulmonary hypertension.

BACKGROUND: The prognosis of Pulmonary Hypertension (PH) is directly correlated with the functional capacity (FC). The most common FC test is the 6-Minute Walk Test (6MWT), however, there is evidence to suggest that the 6MWT does not reflect the real FC in PH patients. AIM: To compare physiological responses among three field walk tests and cardiopulmonary exercise testing (CPET) in patients with pulmonary hypertension (PH), and to determine the determinants of distance walked in the field walk tests. DESIGN: Cross sectional study. SETTING: Outpatient clinic. POPULATION: 26 volunteers (49.8±14.6 years), WHO functional class II-III and a mean pulmonary artery pressure of 45 mmHg. METHODS: Patients underwent three field walk test: 6MWT, incremental shuttle walk test (ISWT), and endurance shuttle walk test (ESWT) and CPET on different, non-consecutive days. The main outcome measures were heart rate and perception of effort at the peak of exercise. RESULTS: The ISWT achieved maximum levels of effort without significant difference in any physiologic response compared to CPET. The physiological responses during ISWT were significantly higher than 6MWT and ESWT responses. CONCLUSIONS: The ISWT produced the greatest physiologic response of the field tests safely for which reason it appears to be the most effective test to assess FC of PH patients. CLINICAL REHABILITATION IMPACT: The self-paced characteristic of the 6MWT and lower physiologic responses compared to the CPET were the main reason for this test to be classified as submaximal in PH patients. The physiological responses during the ESWT were significantly lower than other field tests highlighting the need for more research on this test and other field test in PH patients.

Evaluation of autonomic modulation of lung function and heart rate in children with cystic fibrosis.

The autonomic nervous system (ANS) plays an important role in modulating bronchial smooth muscle contractility, which is altered in cystic fibrosis (CF). A convenient approach to probe ANS regulation is the quantitative analysis of heart rate variability (HRV). The purpose of this study was to evaluate ANS regulation in children with CF and to investigate the influence of colonization by Pseudonomas aeruginosa via assessment of HRV in colonized CF (CCF) children and noncolonized CF (NCCF) children. Sixteen children with CF (7 CCF and 9 NCCF) and seven healthy age-matched control children were enrolled in the study. Heart rate was recorded for 10 min at rest in the supine and standing positions and HRV analysis was carried out using autoregressive spectral analysis. The CCF group was characterized by lower forced expiratory volume than NCCF, indicating an impairment of respiratory function. The HRV parameters further confirmed the possible sympathetic overactivity in CCF. Children with CF exhibited hyperactivity of the sympathetic nervous system. In particular, the CCF group presented a greater impairment of ANS modulation. Both CCF and NCCF children showed lower supine vagal activation in the HRV indices related to sympathetic activation and reduction of indices indicating vagal activity with the postural change from supine to standing when compared to the NCCF group.

Prevalence and severity of syndrome Z in women with metabolic syndrome on waiting list for bariatric surgery: a cross-sectional study.

BACKGROUND: In recent years, obesity has become one of the most important public health problems in the world, with a growing prevalence in both developed and developing countries. Recent studies show that sleep disturbances, especially obstructive sleep apnoea (OSA) may be a manifestation of metabolic syndrome (MetS). Although the association of OSA with the MetS is largely attributed to obesity, the exact pathophysiological mechanisms and their individual characteristics still need to be identified. This study investigated the prevalence and severity of syndrome Z in obese women with MetS on waiting list for bariatric surgery. METHODS: In this double-center cross-sectional study, female patients aged ≥18 years, stage III severe obesity with MetS, on waiting list for bariatric surgery were recruited. The diagnosis for MetS was made according to the criteria of the national cholesterol education program, adult treatment panel III. Clinical, anthropometric, demographic, biochemistry, and sleep measurements were collected. Correlations between continuous variables with sleep parameters were performed using the Pearson correlation test or Spearman correlation test. RESULTS: The mean age of 83 patients was 44.8 ± 11.2 years and mean BMI was 42.6 ± 8.1 kg/m2. There was a significant correlation between OSA and metabolic score (r = 0.336; P = 0.002), neck circumference (r = 0.218; P = 0.048), basal systolic blood pressure (r = 0.280; P = 0.01), total cholesterol (r = 0.277; P = 0.011) and abdomen circumference (r = 0.284; P = 0.009). The mean values of excessive daytime sleepiness were 10.5 ± 7 demonstrating a value considered normal for its presence. However, a high risk for OSA was observed in practically the entire population. It was observed that the prevalence of Syndrome Z (75.9%) increased significantly according to apnoea hypopnoea index (AHI) (P for trend <0.0000). A prevalence of 27.71% for mild OSA, 20.48% for moderate OSA, and 27.71% for severe OSA was observed. An association of AHI severity with all components of MetS was also observed. CONCLUSIONS: We can conclude that syndrome Z presents a high prevalence in a female population with MetS and a considerable severity according to the presence of OSA. Therefore, patients with MetS should be investigated for the presence of sleep disorders. Trial registration The study has been registered on ClinicalTrials.gov NCT02409160 and followed the standards of The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement: guidelines for reporting observational studies.

Incremental shuttle walking test: a reproducible and valid test to evaluate exercise tolerance in adults with noncystic fibrosis bronchiectasis.

OBJECTIVE: To analyze the reliability, validity, and determinants of the incremental shuttle walk test (ISWT) in adults with noncystic fibrosis bronchiectasis. DESIGN: Cross-sectional study. SETTING: Outpatient clinic. PARTICIPANTS: Subjects (N=75; 26 men) underwent, on different days, cardiopulmonary exercise testing (CPET) and 2 ISWTs, 30 minutes apart. The number of steps in daily life was recorded. Concurrent validity was tested by the relation between distance walked with peak load and oxygen consumption (V˙o2). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Distance walked (m) was compared between the first and second ISWTs; greatest distance walked was correlated with peak load and Vo2peak obtained from CPET, steps per day, and dyspnea evaluated by the Medical Research Council (MRC) scale; and desaturation was compared between CPET and the ISWT. RESULTS: Distance walked was equivalent between the first ISWT (441±152m) and the second ISWT (445±153m) with an excellent intraclass correlation coefficient (.995; 95% confidence interval, .99-.997). There were significant correlations between distance walked and peak load (r=.82), V˙o2 (r=.72), steps per day (r=.61), and the MRC scale (r=-.69). Age, body mass index, sex, forced vital capacity (% predicted), dyspnea, and steps per day explained 70% of the variation in distance walked (m) and 60% of the variance when expressed as percent predicted. Higher desaturation was observed during the ISWT (-4%±4%) than cycling (-2±3%) (P<.001). CONCLUSIONS: The ISWT is reliable, represents functional capacity, and induces greater desaturation than cycling. Age, body composition, pulmonary function, dyspnea, and physical activity in daily life are determinants of the distance walked on the ISWT.

Clinical significance in COPD patients followed in a real practice.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is an important public health issue in many countries which is estimated to become the fifth cause of disability and the third cause of mortality in the world within 2020.The objective of this study was to identify the clinical characteristics in the real clinical practice of a sample of patients with COPD followed in a pulmonology clinic. METHODS: The initial sample contained 207 subjects with respiratory claims that searched for specialized treatment and initiated regular monitoring between 2004 and 2009 in a private clinic localized in Cascavel, in the state of Parana, Brazil. Demographic data (weight, height, body mass index - BMI), history of comorbidities, use of respiratory and non respiratory drugs were also registered. RESULTS: The main cause related to the development of COPD was current or prior smoking (92.0%); the most frequently reported symptom was dyspnea (95.0%), followed by cough (86.1%), wheezing (69.4%) and sputum production (40.0%). During the follow up, 51 patients developed the need for oxygen therapy (28.3%). In 96 patients, there were periods of acute exacerbation, resulting in 37 hospitalizations. In addition to COPD, a significant number of comorbidities were identified, being cardiovascular disease and neurological disorders the most prevalent ones. CONCLUSIONS: Based on the data collected, we could outline the profile of patients with COPD, showing characteristics of an elderly population, with multiple comorbidities, suggesting a health related quality of life lower than expected.

Effect of treadmill gait training on static and functional balance in children with cerebral palsy: a randomized controlled trial.

BACKGROUND: Treadmill gait training as a therapeutic resource in the rehabilitation of children with cerebral palsy has recently been the focus of many studies; however, little is still known regarding its effect on static and functional balance in children. OBJECTIVE: The aim of the present study was to compare the effects of treadmill training and over ground gait training in children with cerebral palsy. METHOD: A randomized controlled trial with blinded evaluator was conducted with children with cerebral palsy between three and 12 years of age categorized in Levels I to III of the Gross Motor Function Classification System. Assessments were performed before and after the intervention and involved the Berg balance scale as well as the determination of oscillations from the center of pressure in the anteroposterior and mediolateral directions with eyes open and closed. The experimental group was submitted to treadmill training and the control group performed gait training over the ground. The intervention consisted of two 30-minute sessions per week for seven weeks. RESULTS: Both groups exhibited better functional balance after the protocol. The experimental group had higher Berg balance scale scores and exhibited lesser mediolateral oscillation with eyes open in comparison to the control group. CONCLUSIONS: Treadmill training had a greater effect on functional balance and mediolateral oscillation in comparison to over ground gait training in children with cerebral palsy. TRIAL REGISTRATION: RBR-5v3kg9.(Brazilian Registry of Clinical Trials).

Effect of treadmill gait training on static and functional balance in children with cerebral palsy: a randomized controlled trial

BACKGROUND: Treadmill gait training as a therapeutic resource in the rehabilitation of children with cerebral palsy has recently been the focus of many studies; however, little is still known regarding its effect on static and functional balance in children. OBJECTIVE: The aim of the present study was to compare the effects of treadmill training and over ground gait training in children with cerebral palsy. METHOD: A randomized controlled trial with blinded evaluator was conducted with children with cerebral palsy between three and 12 years of age categorized in Levels I to III of the Gross Motor Function Classification System. Assessments were performed before and after the intervention and involved the Berg balance scale as well as the determination of oscillations from the center of pressure in the anteroposterior and mediolateral directions with eyes open and closed. The experimental group was submitted to treadmill training and the control group performed gait training over the ground. The intervention consisted of two 30-minute sessions per week for seven weeks. RESULTS: Both groups exhibited better functional balance after the protocol. The experimental group had higher Berg balance scale scores and exhibited lesser mediolateral oscillation with eyes open in comparison to the control group. CONCLUSIONS: Treadmill training had a greater effect on functional balance and mediolateral oscillation in comparison to over ground gait training in children with cerebral palsy. Trial registration: RBR-5v3kg9.(Brazilian Registry of Clinical Trials).

Chest physical therapy is effective in reducing the clinical score in bronchiolitis: randomized controlled trial / A fisioterapia respiratória é eficaz na redução de escore clínico na bronquiolite: ensaio controlado randomizado

OBJECTIVE: To evaluate the effectiveness of chest physical therapy (CP) in reducing the clinical score in infants with acute viral bronchiolitis (AVB). METHODS: Randomized controlled trial of 30 previously healthy infants (mean age 4.08 SD 3.0 months) with AVB and positive for respiratory syncytial virus (RSV), evaluated at three moments: at admission, then at 48 and 72 hours after admission. The procedures were conducted by blinded assessors to each of three groups: G1 - new Chest Physical therapy- nCPT (Prolonged slow expiration - PSE and Clearance rhinopharyngeal retrograde - CRR), G2 - conventional Chest Physical therapy- cCPT (modified postural drainage, expiratory compression, vibration and percussion) and G3 - aspiration of the upper airways. The outcomes of interest were the Wang's clinical score (CS) and its components: Retractions (RE), Respiratory Rate (RR), Wheezing (WH) and General Conditions (GC). RESULTS: The CS on admission was reduced in G1 (7.0-4.0) and G2 (7.5-5.5) but was unchanged in G3 (7.5-7.0). We observed a change 48 hours after hospitalization in G1 (5.5-3.0) and G2 (4.0-2.0) and in 72 hours, there was a change in G1 (2.0-1.0). CONCLUSION: The CP was effective in reducing the CS in infants with AVB compared with upper airway suction only. After 48 hours of admission, both techniques were effective and nCPT techniques were also effective in the 72 hours after hospitalization compared with cCPT techniques.

OBJETIVO: Avaliar a efetividade da fisioterapia respiratória na redução do escore clínico em lactentes com bronquiolite viral aguda (BVA). MÉTODOS: Ensaio controlado randomizado de 30 lactentes (média de idade 4,08±3,12 meses) com BVA, previamente hígidos, com vírus sincicial respiratório (VSR) positivo, avaliados em três momentos: admissão, 48 e 72 horas, antes e após os procedimentos por avaliadores cegos, em três grupos: G1 - técnicas atuais de fisioterapia (expiração lenta e prolongada e desobstrução rinofaríngea retrógrada), G2 - técnicas convencionais de fisioterapia (drenagem postural modificada, compressão expiratória, vibração e percussão) e G3 - aspiração de vias aéreas superiores por meio do escore clínico de Wang e seus componentes: retrações (RE), frequência respiratória (RR), sibilos (WH) e condições gerais (GC). RESULTADOS: O escore clínico de Wang (CS) no momento admissão, no G1, reduziu de 7,0-4,0; no G2, de 7,5-5,5 e no G3 de 7,5-7,0, não apresentando alteração. No momento 48 horas, também houve alteração tanto no G1 (5,5-3,0) quanto no G2 (4,0-2,0) e, em 72 horas, apenas no G1 (2,0-1,0). CONCLUSÃO: A fisioterapia respiratória foi efetiva na redução do escore clínico em lactentes com BVA quando comparada com a aspiração isolada das vias aéreas na admissão. No momento 48 horas, ambas as técnicas foram efetivas, sendo que as técnicas atuais foram efetivas também nas 72 horas após a internação, comparada às técnicas convencionais.

Static balance and function in children with cerebral palsy submitted to neuromuscular block and neuromuscular electrical stimulation: study protocol for prospective, randomized, controlled trial.

BACKGROUND: The use of botulinum toxin A (BT-A) for the treatment of lower limb spasticity is common in children with cerebral palsy (CP). Following the administration of BT-A, physical therapy plays a fundamental role in potentiating the functionality of the child. The balance deficit found in children with CP is mainly caused by muscle imbalance (spastic agonist and weak antagonist). Neuromuscular electrical stimulation (NMES) is a promising therapeutic modality for muscle strengthening in this population. The aim of the present study is to describe a protocol for a study aimed at analyzing the effects of NMES on dorsiflexors combined with physical therapy on static and functional balance in children with CP submitted to BT- A. METHODS/DESIGN: Protocol for a prospective, randomized, controlled trial with a blinded evaluator. Eligible participants will be children with cerebral palsy (Levels I, II and III of the Gross Motor Function Classification System) between five and 12 years of age, with independent gait with or without a gait-assistance device. All participants will receive BT-A in the lower limbs (triceps surae). The children will then be randomly allocated for either treatment with motor physical therapy combined with NMES on the tibialis anterior or motor physical therapy alone. The participants will be evaluated on three occasions: 1) one week prior to the administration of BT-A; 2) one week after the administration of BT-A; and 3) four months after the administration of BT-A (end of intervention). Spasticity will be assessed by the Modified Ashworth Scale and Modified Tardieu Scale. Static balance will be assessed using the Medicapteurs Fusyo pressure platform and functional balance will be assessed using the Berg Balance Scale. DISCUSSION: The aim of this protocol study is to describe the methodology of a randomized, controlled, clinical trial comparing the effect of motor physical therapy combined with NMES on the tibialis anterior muscle or motor physical therapy alone on static and functional balance in children with CP submitted to BT-A in the lower limbs. This study describes the background, hypotheses, methodology of the procedures and measurement of the results. TRIAL REGISTRATION: RBR5qzs8h.

Chest physical therapy is effective in reducing the clinical score in bronchiolitis: randomized controlled trial.

OBJECTIVE: To evaluate the effectiveness of chest physical therapy (CP) in reducing the clinical score in infants with acute viral bronchiolitis (AVB). METHODS: Randomized controlled trial of 30 previously healthy infants (mean age 4.08 SD 3.0 months) with AVB and positive for respiratory syncytial virus (RSV), evaluated at three moments: at admission, then at 48 and 72 hours after admission. The procedures were conducted by blinded assessors to each of three groups: G1 - new Chest Physical therapy- nCPT (Prolonged slow expiration - PSE and Clearance rhinopharyngeal retrograde - CRR), G2 - conventional Chest Physical therapy- cCPT (modified postural drainage, expiratory compression, vibration and percussion) and G3 - aspiration of the upper airways. The outcomes of interest were the Wang's clinical score (CS) and its components: Retractions (RE), Respiratory Rate (RR), Wheezing (WH) and General Conditions (GC). RESULTS: The CS on admission was reduced in G1 (7.0-4.0) and G2 (7.5-5.5) but was unchanged in G3 (7.5-7.0). We observed a change 48 hours after hospitalization in G1 (5.5-3.0) and G2 (4.0-2.0) and in 72 hours, there was a change in G1 (2.0-1.0). CONCLUSION: The CP was effective in reducing the CS in infants with AVB compared with upper airway suction only. After 48 hours of admission, both techniques were effective and nCPT techniques were also effective in the 72 hours after hospitalization compared with cCPT techniques.

Observational study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers--protocol study.

BACKGROUND: Obstructive sleep apnea (OSA) is a respiratory disease characterized by the collapse of the extrathoracic airway and has important social implications related to accidents and cardiovascular risk. The main objective of the present study was to investigate whether the drop in expiratory flow and the volume expired in 0.2 s during the application of negative expiratory pressure (NEP) are associated with the presence and severity of OSA in a population of professional interstate bus drivers who travel medium and long distances. METHODS/DESIGN: An observational, analytic study will be carried out involving adult male subjects of an interstate bus company. Those who agree to participate will undergo a detailed patient history, physical examination involving determination of blood pressure, anthropometric data, circumference measurements (hips, waist and neck), tonsils and Mallampati index. Moreover, specific questionnaires addressing sleep apnea and excessive daytime sleepiness will be administered. Data acquisition will be completely anonymous. Following the medical examination, the participants will perform a spirometry, NEP test and standard overnight polysomnography. The NEP test is performed through the administration of negative pressure at the mouth during expiration. This is a practical test performed while awake and requires little cooperation from the subject. In the absence of expiratory flow limitation, the increase in the pressure gradient between the alveoli and open upper airway caused by NEP results in an increase in expiratory flow. DISCUSSION: Despite the abundance of scientific evidence, OSA is still underdiagnosed in the general population. In addition, diagnostic procedures are expensive, and predictive criteria are still unsatisfactory. Because increased upper airway collapsibility is one of the main determinants of OSA, the response to the application of NEP could be a predictor of this disorder. With the enrollment of this study protocol, the expectation is to encounter predictive NEP values for different degrees of OSA in order to contribute toward an early diagnosis of this condition and reduce its impact and complications among commercial interstate bus drivers. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clinicos (local acronym RBEC) [Internet]: Rio de Janeiro (RJ): Instituto de Informaçao Cientifica e Tecnologica em Saude (Brazil); 2010 - Identifier RBR-7dq5xx. Cross-sectional study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers; 2011 May 31 [7 pages]. Available from http://www.ensaiosclinicos.gov.br/rg/RBR-7dq5xx/.

Sleep study, respiratory mechanics, chemosensitive response and quality of life in morbidly obese patients undergoing bariatric surgery: a prospective, randomized, controlled trial.

BACKGROUND: Obesity is a major public health problem in both developed and developing countries alike and leads to a series of changes in respiratory physiology. There is a strong correlation between obesity and cardiopulmonary sleep disorders. Weight loss among such patients leads to a reduction in these alterations in respiratory physiology, but clinical treatment is not effective for a long period of time. Thus, bariatric surgery is a viable option. METHODS/DESIGN: The present study involves patients with morbid obesity (BMI of 40 kg/m2 or 35 kg/m2 to 39.9 kg/m2 with comorbidities), candidates for bariatric surgery, screened at the Santa Casa de Misericórdia Hospital in the city of Sao Paulo (Brazil). The inclusion criteria are grade III morbid obesity, an indication for bariatric surgery, agreement to participate in the study and a signed term of informed consent. The exclusion criteria are BMI above 55 kg/m2, clinically significant or unstable mental health concerns, an unrealistic postoperative target weight and/or unrealistic expectations of surgical treatment. Bariatric surgery candidates who meet the inclusion criteria will be referred to Santa Casa de Misericórdia Hospital and will be reviewed again 30, 90 and 360 days following surgery. Data collection will involve patient records, personal data collection, objective assessment of HR, BP, neck circumference, chest and abdomen, collection and analysis of clinical preoperative findings, polysomnography, pulmonary function test and a questionnaire on sleepiness. DISCUSSION: This paper describes a randomised controlled trial of morbidly obese patients. Polysomnography, respiratory mechanics, chemosensitive response and quality of life will be assessed in patients undergoing or not undergoing bariatric surgery. TRIAL REGISTRATION: The protocol for this study is registered with the Brazilian Registry of Clinical Trials - ReBEC (RBR-9k9hhv).

Outpatient vs. home-based pulmonary rehabilitation in COPD: a randomized controlled trial.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a common cause of morbidity and mortality affecting a large number of individuals in both developed and developing countries and it represents a significant financial burden for patients, families and society. Pulmonary rehabilitation (PR) is a multidisciplinary program that integrates components of exercise training, education, nutritional support, psychological support and self-care, resulting in an improvement in dyspnea, fatigue and quality of life. Despite its proven effectiveness and the strong scientific recommendations for its routine use in the care of COPD, PR is generally underutilized and strategies for increasing access to PR are needed. Home-based self-monitored pulmonary rehabilitation is an alternative to outpatient rehabilitation. In the present study, patients with mild, moderate and severe COPD submitted to either an outpatient or at-home PR program for 12 weeks were analyzed. METHODS: Patients who fulfilled the inclusion criteria were randomized into three distinct groups: an outpatient group who performed all activities at the clinic, a home-based group who performed the activities at home and a control group. PR consisted of a combination of aerobic exercises and strengthening of upper and lower limbs 3 times a week for 12 weeks. RESULTS: There was a significant difference in the distance covered on the six-minute walk test (p < 0.05) and BODE index (p < 0.001) in the outpatient and at-home groups after participating in the rehabilitation program compared to baseline. CONCLUSION: A home-based self-monitoring pulmonary rehabilitation program is as effective as outpatient pulmonary rehabilitation and is a valid alternative for the management of patients with COPD.

Assessment of plantar pressure and balance in patients with diabetes.

INTRODUCTION: Patients with diabetes for more than 10 years may have an increase in peak plantar pressure, considerable postural oscillation, balance deficit, alterations in gait pattern and an increased risk of falls. The aim of the present study was to assess the correlation between plantar pressure distribution and balance in patients with diabetes using a pressure platform (Footwork). MATERIAL AND METHODS: The study was carried out at the Human Movement Clinic of the Centro Universitário de Belo Horizonte (Brazil). The sample was made up of 18 right-handed individuals with type 2 diabetes - 14 females and 4 males - with an average age of 58.72 ±9.54 and an average of 18.56 ±6.61 years since diagnosis. RESULT: Data analysis revealed that greater peak plantar pressure on the right hindfoot led to greater radial displacement (Rd) (r = 0.2022) and greater displacement velocity (r = 0.2240). Greater peak plantar pressure on the left hindfoot also led to greater displacement velocity (P) (r = 0.5728) and radial displacement (RD) (r = 0.1972). A positive correlation was found between time elapsed since diagnosis and peak midfoot pressure (r = 0.3752) on the right and left side as well as between BMI and plantar pressure on all regions of the foot. CONCLUSIONS: The data reveal a correlation between postural oscillation and peak plantar pressure on the hindfoot.

Acute effects of different levels of continuous positive airway pressure on cardiac autonomic modulation in chronic heart failure and chronic obstructive pulmonary disease.

INTRODUCTION: Non-invasive ventilation may improve autonomic modulation and ventilatory parameters in severely disabled patients. The aim of the present study was to evaluate the physiological influence of acute treatment with different levels of continuous positive airway pressure (CPAP) on the autonomic balance of heart and respiratory responses in patients with stable chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). MATERIALS AND METHODS: A COPD group (n = 10), CHF group (n = 8) and healthy subjects (n = 10) were evaluated. The participants were randomized to receive three different levels of CPAP on the same day: sham ventilation (Sham), 5 cmH(2)0 (CPAP5) and 10 cmH(2)0 (CPAP10) for 10 min. Respiratory rate, end tidal carbon dioxide (E(T)CO(2)), peripheral oxygen saturation (SpO(2)), heart rate (HR), blood pressure and heart rate variability in the time and frequency domains were measured during spontaneous breathing and under the sham, CPAP5 and CPAP10 conditions. RESULTS: All groups experienced a reduction in E(T)CO(2) values during treatment with CPAP (p < 0.05). CPAP increased SpO(2) and HR in the COPD group (p < 0.05). The COPD group also had lower RMSSD values during treatment with different levels of CPAP when compared to the control group (p < 0.05). In the CHF group, CPAP5 and CPAP10 increased the SDNN value (p < 0.05). CPAP10 reduced the SDNN value in the COPD group (p < 0.05). CONCLUSION: The findings suggest that CPAP may cause improvements in the neural control of heart rate in patients with stable COPD and CHF. For each patient, the "best CPAP level" should be defined as the best respiratory response and autonomic balance.