The strength of the respiratory muscles can be evaluated from static measurements (maximal inspiratory and expiratory pressures, MIP and MEP) or inferred from dynamic maneuvers (maximal voluntary ventilation, MVV). Although these data could be suitable for a number of clinical and research applications, no previous studies have provided reference values for such tests using a healthy, randomly selected sample of the adult Brazilian population. With this main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, selected from more than 8,000 individuals. Gender-specific linear prediction equations for MIP, MEP and MVV were developed by multiple regression analysis: age and, secondarily, anthropometric measurements explained up to 56% of the variability of the dependent variables. The most cited previous studies using either Caucasian or non-Caucasian samples systematically underestimated the observed values of MIP (P<0.05). Interestingly, the self-reported level of regular physical activity and maximum aerobic power correlates strongly with both respiratory and peripheral muscular strength (knee extensor peak torque) (P<0.01). Our results, therefore, provide a new frame of reference to evaluate the normalcy of some useful indexes of respiratory muscle strength in Brazilian males and females aged 20 to 80.

This document reviews 1) the measurement properties of commonly used exercise tests in patients with chronic respiratory diseases and 2) published studies on their utilty and/or evaluation obtained from MEDLINE and Cochrane Library searches between 1990 and March 2015.Exercise tests are reliable and consistently responsive to rehabilitative and pharmacological interventions. Thresholds for clinically important changes in performance are available for several tests. In pulmonary arterial hypertension, the 6-min walk test (6MWT), peak oxygen uptake and ventilation/carbon dioxide output indices appear to be the variables most responsive to vasodilators. While bronchodilators do not always show clinically relevant effects in chronic obstructive pulmonary disease, high-intensity constant work-rate (endurance) tests (CWRET) are considerably more responsive than incremental exercise tests and 6MWTs. High-intensity CWRETs need to be standardised to reduce interindividual variability. Additional physiological information and responsiveness can be obtained from isotime measurements, particularly of inspiratory capacity and dyspnoea. Less evidence is available for the endurance shuttle walk test. Although the incremental shuttle walk test and 6MWT are reliable and less expensive than cardiopulmonary exercise testing, two repetitions are needed at baseline. All exercise tests are safe when recommended precautions are followed, with evidence suggesting that no test is safer than others. @ERSpublications A review of exercise testing to evaluate interventions aimed to improve exercise tolerance in respiratory patients

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These data are consistent with the notion that inspiratory muscles may be net consumers of lactate during recovery from intense exercise.

We tested the hypothesis that transcutaneous electrical nerve stimulation (TENS) over the stellate ganglion region would reduce sympathetic overstimulation and improve femoral blood flow (FBF) after coronary artery bypass graft surgery. Thirty-eight patients (20 men, 24 New York Heart Association class III-IV) were randomized to 5-day postoperative TENS (n = 20; 4 times/day; 30 min/session) or sham TENS (n = 18) applied to the posterior cervical region (C7-T4). Sympathetic nervous system was stimulated by the cold pressor test, with FBF being measured by ultrasound Doppler. Femoral vascular conductance (FVC) was calculated as FBF/mean arterial pressure (MAP). Six-min walking distance established patients' functional capacity. Before and after the intervention periods, pain scores, opiate requirements, and circulating β-endorphin levels were determined. As expected, preoperative MAP increased and FBF and FVC decreased during the cold pressor test. Sham TENS had no significant effect on these variables (P > 0.05). In contrast, MAP decreased in the TENS group (125 ± 12 vs. 112 ± 10 mmHg). This finding, in association with a consistent increase in FBF (95 ± 5 vs. 145 ± 14 ml/min), led to significant improvements in FVC (P < 0.01). Moreover, 6-min walking distance improved only with TENS (postsurgery-presurgery = 35 ± 12 vs. 6 ± 10 m; P < 0.01). TENS was associated with lesser postoperative pain and opiate requirements but greater circulating β-endorphin levels (P < 0.05). In conclusion, stellate ganglion TENS after coronary artery bypass graft surgery positively impacted on limb blood flow during a sympathetic stimulation maneuver, a beneficial effect associated with improved clinical and functional outcomes.

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Background: Pulmonary gas exchange impairment (GEI) is a common consequence of intrathoracic sarcoidosis presenting with important therapeutic and prognostic implications. Objective: To determine the role of clinical, radiographic and functional variables in predicting GEI during moderate exercise at the estimated lactate threshold (Θ_L) in patients with sarcoidosis. Methods: Fifty-four outpatients (29 females) with biopsy-proven sarcoidosis had clinical evaluation (baseline dyspnea index), lung function tests and an incremental cardiopulmonary exercise test with Θ_L estimation. On a separate day, patients underwent a constant work rate test at Θ_L with assessment of arterial blood gas tensions. Results: There was no evidence of GEI [ΔP (A – a) O₂/VO₂ >20 mm Hg·l· min^–1] in patients with radiographic stages 0–I (n = 13). In the remaining 41 patients, GEI was associated with more extensive radiographic involvement and reduced diffusing capacity of the lung for carbon monoxide (DL_CO), forced expiratory volume in 1 s, total lung capacity and forced vital capacity (% predicted;p < 0.05); baseline dyspnea index and resting arterial blood gas tensions, in contrast, were not significantly related to GEI. DL_CO correlated best with GEI. The negative predictive value of DL_CO >70% predicted (absent-to-mild impairment) was 91.3% (sensitivity = 81.8%) and the positive predictive value of DL_CO ≤50% predicted (severe impairment) was 83.3% (specificity = 96.6%, likelihood ratio = 13.35). There was no improvement in diagnostic accuracy when other physiological tests were added to DL_CO. These results were consistent with those found in a multiple logistic regression analysis with GEI as the dependent variable (p < 0.01). Conclusions: Conventional chest radiography and DL_CO measurements suffice to estimate the individual risk of GEI at moderate exercise in patients with sarcoidosis.

Ventilatory inefficiency remains a powerful prognostic marker in HF despite the presence of mechanical ventilatory constraints induced by COPD. If these preliminary findings are confirmed in larger studies, optimal thresholds for outcome prediction are likely greater than those traditionally recommended for HF patients without COPD.