ATS/ACCP statement on cardiopulmonary exercise testing.

Evidence-based recommendations on the clinical use of cardiopulmonary exercise testing (CPET) in lung and heart disease are presented, with reference to the assessment of exercise intolerance, prognostic assessment and the evaluation of therapeutic interventions (e.g. drugs, supplemental oxygen, exercise training). A commonly used grading system for recommendations in evidence-based guidelines was applied, with the grade of recommendation ranging from A, the highest, to D, the lowest. For symptom-limited incremental exercise, CPET indices, such as peak O(2) uptake (V'O(2)), V'O(2) at lactate threshold, the slope of the ventilation-CO(2) output relationship and the presence of arterial O(2) desaturation, have all been shown to have power in prognostic evaluation. In addition, for assessment of interventions, the tolerable duration of symptom-limited high-intensity constant-load exercise often provides greater sensitivity to discriminate change than the classical incremental test. Field-testing paradigms (e.g. timed and shuttle walking tests) also prove valuable. In turn, these considerations allow the resolution of practical questions that often confront the clinician, such as: 1) "When should an evaluation of exercise intolerance be sought?"; 2) "Which particular form of test should be asked for?"; and 3) "What cluster of variables should be selected when evaluating prognosis for a particular disease or the effect of a particular intervention?"

https://erj.ersjournals.com/content/erj/29/1/185.full.pdf

Recommendations on the use of exercise testing in clinical practice

Background: Passive training of specific locomotor muscle groups by means of neuromuscular electrical stimulation (NMES) might be better tolerated than whole body exercise in patients with severe chronic obstructive pulmonary disease (COPD). It was hypothesised that this novel strategy would be particularly effective in improving functional impairment and the consequent disability which characterises patients with end stage COPD. Methods: Fifteen patients with advanced COPD (nine men) were randomly assigned to either a home based 6 week quadriceps femoris NMES training programme (group 1, n=9, FEV 1 =38.0 (9.6)% of predicted) or a 6 week control period before receiving NMES (group 2, n=6, FEV 1 =39.5 (13.3)% of predicted). Knee extensor strength and endurance, whole body exercise capacity, and health related quality of life (Chronic Respiratory Disease Questionnaire, CRDQ) were assessed. Results: All patients were able to complete the NMES training programme successfully, even in the presence of exacerbations (n=4). Training was associated with significant improvements in muscle function, maximal and endurance exercise tolerance, and the dyspnoea domain of the CRDQ (p Conclusions: For severely disabled COPD patients with incapacitating dyspnoea, short term electrical stimulation of selected lower limb muscles involved in ambulation can improve muscle strength and endurance, whole body exercise tolerance, and breathlessness during activities of daily living.

https://thorax.bmj.com/content/thoraxjnl/57/4/333.full.pdf

Home based neuromuscular electrical stimulation as a new rehabilitative strategy for severely disabled patients with chronic obstructive pulmonary disease (COPD)

The activities of daily living typically occur at metabolic rates below the maximum rate of aerobic energy production. Such activity is characteristic of the nonsteady state, where energy demands, and consequential physiological responses, are in constant flux. The dynamics of the integrated physiological processes during these activities determine the degree to which exercise can be supported through rates of O₂ utilization and CO₂ clearance appropriate for their demands and, as such, provide a physiological framework for the notion of exercise intensity. The rate at which O₂ exchange responds to meet the changing energy demands of exercise--its kinetics--is dependent on the ability of the pulmonary, circulatory, and muscle bioenergetic systems to respond appropriately. Slow response kinetics in pulmonary O₂ uptake predispose toward a greater necessity for substrate-level energy supply, processes that are limited in their capacity, challenge system homeostasis and hence contribute to exercise intolerance. This review provides a physiological systems perspective of pulmonary gas exchange kinetics: from an integrative view on the control of muscle oxygen consumption kinetics to the dissociation of cellular respiration from its pulmonary expression by the circulatory dynamics and the gas capacitance of the lungs, blood, and tissues. The intensity dependence of gas exchange kinetics is discussed in relation to constant, intermittent, and ramped work rate changes. The influence of heterogeneity in the kinetic matching of O₂ delivery to utilization is presented in reference to exercise tolerance in endurance-trained athletes, the elderly, and patients with chronic heart or lung disease.

Exercise: Kinetic considerations for gas exchange.

Exercise tests are commonly used in clinical practice for both functional and diagnostic assessments. Many exercise tests are designed to produce a single measurement relevant to a specific clinical setting such as a timed walking distance as a measure of functional capacity in rehabilitation candidates or the presence of ECG changes consistent with myocardial ischemia in patients with chest pain. Cardiopulmonary exercise testing (CPX) measures a broader range of variables related to cardiorespiratory function, including expiratory ventilation (Ve) and pulmonary gas exchange (oxygen uptake [Vo2] and carbon dioxide output [Vco2]), along with the ECG and blood pressure, with the goal of quantitatively linking metabolic, cardiovascular, and pulmonary responses to exercise.1,–,3 With increased availability of instruments for the facile measurement of exercise gas exchange, experience with CPX has expanded from clinical research applications to a broad range of clinical practice settings.4

Interpretation of CPX for clinical purposes includes comparison of data from individual patients with those from healthy and disease populations. Substantial data are available characterizing exercise responses of patients with certain common heart and lung diseases, providing a basis for using CPX to compare individual patients' impairment relative to others from the same populations. Diagnostic applications of CPX, eg, for evaluating unexplained dyspnea or exercise intolerance, also rely on a comparison of patients' data with those of patients with known diagnoses. In clinical practice, in contrast to much of the research related to specific disorders, patients frequently have multiple medical problems, confounding the assessment of impairment or the attribution of symptoms to one or another condition. Although there are few systematic analyses of the effects of coexistent conditions on exercise responses, an advantage of CPX compared with other forms of testing is the potential for gaining insight …

Cardiopulmonary Exercise Testing in the Clinical Evaluation of Patients With Heart and Lung Disease

All of the most widely-cited studies for the prediction of maximum exercise responses have utilized either volunteers or referred subjects. Therefore, selection bias, with overestimation of the reference values, is a likely consequence. In order to establish a set of predictive equations for the gas exchange, ventilatory and cardiovascular responses to maximum ramp-incremental cycle ergometry, this study prospectively evaluated 120 sedentary individuals (60 males, 60 females, aged 20-80), randomly-selected from >8,000 subjects. Regular physical activity pattern by questionnaire, body composition by anthropometry and dual energy X-ray absorptiometry (n = 75) and knee strength by isokinetic dynamometry were also assessed. Previously reported equations typically overestimated the subjects' peak oxygen uptake (p<0.05). Prediction linear equations for the main variables of clinical interest were established by backward stepwise regression analysis including: sex, age, knee extensor peak torque, bone-free lean leg mass, total and lean body mass, height, and physical activity scores. Reference intervals (95% confidence limits) were calculated: some of these values differed markedly from those formerly recommended. The results therefore might provide a more appropriate frame of reference for interpretation of the responses to symptom-limited ramp incremental cycle ergometry in sedentary subjects; i.e. those usually referred for clinical cardiopulmonary exercise tests.

https://erj.ersjournals.com/content/erj/14/6/1304.full.pdf

Prediction of metabolic and cardiopulmonary responses to maximum cycle ergometry: a randomised study

Aims: To investigate the consequences of improvement in the workplace environment over six decades (1940–96) in asbestos miners and millers from a developing country (Brazil). Methods: A total of 3634 Brazilian workers with at least one year of exposure completed a respiratory symptoms questionnaire, chest radiography, and a spirometric evaluation. The study population was separated into three groups whose working conditions improved over time: group I (1940–66, n = 180), group II (1967–76, n = 1317), and group III (1977–96, n = 2137). Results: Respiratory symptoms were significantly related to spirometric abnormalities, smoking, and latency time. Breathlessness, in particular, was also associated with age, pleural abnormality and increased cumulative exposure to asbestos fibres. The odds ratios (OR) for parenchymal and/or non-malignant pleural disease were significantly lower in groups II and III compared to group I subjects (0.29 (0.12–0.69) and 0.19 (0.08–0.45), respectively), independent of age and smoking status. Similar results were found when groups were compared at equivalent latency times (groups I v II: 30–45 years; groups II v III: 20–25 years). Ageing, dyspnoea, past and current smoking, and radiographic abnormalities were associated with ventilatory impairment. Lower spirometric values were found in groups I and II compared to group III: lung function values were also lower in higher quartiles of latency and of cumulative exposure in these subjects. Conclusions: Progressive improvement in occupational hygiene in a developing country is likely to reduce the risk of non-malignant consequences of dust inhalation in asbestos miners and millers.

https://oem.bmj.com/content/oemed/62/6/381.full.pdf

A Castelo

Papers

Prediction of metabolic and cardiopulmonary responses to maximum cycle ergometry: a randomised study

Non-malignant consequences of decreasing asbestos exposure in the Brazil chrysotile mines and mills

and mills asbestos exposure in the Brazil chrysotile mines Non-malignant consequences of decreasing