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Activity-related dyspnea in chronic lung disease is centrally related to dynamic (dyn) inspiratory constraints to tidal volume expansion. Lack of reference values for exertional inspiratory reserve (IR) has limited the yield of cardiopulmonary exercise testing in exposing the underpinnings of this disabling symptom. One hundred fifty apparently healthy subjects (82 males) aged 40-85â¯underwent incremental cycle ergometry. Based on exercise inspiratory capacity (ICdyn), we generated centile-based reference values for the following metrics of IR as a function of absolute ventilation: IRdyn1 ([1-(tidal volume/ICdyn)] x 100) and IRdyn2 ([1-(end-inspiratory lung volume/total lung capacity] x 100). IRdyn1 and IRdyn2 standards were typically lower in females and older subjects (p<0.05 for sex and age versus ventilation interactions). Low IRdyn1 and IRdyn2 significantly predicted the burden of exertional dyspnea in both sexes (p<0.01). Using these sex and age-adjusted limits of reference, the clinician can adequately judge the presence and severity of abnormally low inspiratory reserves in dyspneic subjects undergoing cardiopulmonary exercise testing.
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Prueba de Esfuerzo , Humanos , Masculino , Femenino , Anciano , Persona de Mediana Edad , Adulto , Anciano de 80 o más Años , Valores de Referencia , Prueba de Esfuerzo/normas , Volumen de Ventilación Pulmonar/fisiología , Capacidad Inspiratoria/fisiología , Caracteres Sexuales , Inhalación/fisiología , Disnea/fisiopatologíaRESUMEN
BACKGROUND: Continuous monitoring of pulse oximetry (SpO2 ) is recommended during the 6-min walk test (6MWT) to ensure that the lowest SpO2 is recorded. In this case, severe exercise induced desaturation (EID; SpO2 < 80%) triggers walking interruption by the examiner. Our main objective was to assess the impact of this approach on 6MWT distance in patients with chronic respiratory diseases and, second, to evaluate the safety of the test without interruption due to severe EID. METHODS: 6MWTs with continuous monitoring of SpO2 were prospectively performed in subjects with chronic respiratory disease. The participants were randomly allocated to walk with or without SpO2 real-time assessment. SpO2 visualization during the test execution was available only in the first group, and walking interruption was requested by the examiner if SpO2 < 80%. RESULTS: One hundred forty-five participants were included in each group (68.6% females, 62 [52-69] y old) without differences in demographic and resting lung function parameters between them. The main respiratory conditions were COPD (n = 101), asthma (n = 73), pulmonary hypertension (n = 47), and interstitial lung disease (n = 39). The walked distance was similar comparing groups (349.5 ± 117.5 m vs 351.2 ± 105.4 m). Twenty-five subjects presented with severe EID in the group with real-time SpO2 assessment, and 20 subjects had severe EID in the group without real-time assessment respectively (overall prevalence of 15.5%). The 23 participants who had their test interrupted by the examiner due to severe EID in the first group (2 subjects stopped by themselves due to excessive symptoms) walked a shorter distance compared to the 11 subjects with severe EID without test interruption in the second group (9 subjects stopped by themselves due to excessive symptoms): 240.6 ± 100.2 m versus 345.9 ± 73.4 m. No exercise-related serious adverse events were observed. CONCLUSIONS: Interruption driven by severe EID reduced the walked distance during the 6MWT. No serious adverse event, in turn, was observed in subjects with severe desaturation without real-time SpO2 assessment.
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Enfermedad Pulmonar Obstructiva Crónica , Índice de Severidad de la Enfermedad , Humanos , Enfermedad Pulmonar Obstructiva Crónica/clasificación , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Masculino , Femenino , Persona de Mediana Edad , Anciano , Volumen Espiratorio Forzado , Tolerancia al Ejercicio , Ejercicio FísicoRESUMEN
Heightened sensation of leg effort contributes importantly to poor exercise tolerance in patient populations. We aim to provide a sex- and age-adjusted frame of reference to judge symptom's normalcy across progressively higher exercise intensities during incremental exercise. Two-hundred and seventy-five non-trained subjects (130 men) aged 19-85 prospectively underwent incremental cycle ergometry. After establishing centiles-based norms for Borg leg effort scores (0-10 category-ratio scale) versus work rate, exponential loss function identified the centile that best quantified the symptom's severity individually. Peak O2 uptake and work rate (% predicted) were used to threshold gradually higher symptom intensity categories. Leg effort-work rate increased as a function of age; women typically reported higher scores at a given age, particularly in the younger groups (p < 0.05). For instance, "heavy" (5) scores at the 95th centile were reported at ~200 W (<40 years) and ~90 W (≥70 years) in men versus ~130 W and ~70 W in women, respectively. The following categories of leg effort severity were associated with progressively lower exercise capacity: ≤50th ("mild"), >50th to <75th ("moderate"), ≥75th to <95th ("severe"), and ≥ 95th ("very severe") (p < 0.05). Although most subjects reporting peak scores <5 were in "mild" range, higher scores were not predictive of the other categories (p > 0.05). This novel frame of reference for 0-10 Borg leg effort, which considers its cumulative burden across increasingly higher exercise intensities, might prove valuable to judging symptom's normalcy, quantifying its severity, and assessing the effects of interventions in clinical populations.
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Prueba de Esfuerzo , Pierna , Masculino , Humanos , Femenino , Valores de Referencia , Ergometría , Ejercicio Físico , Consumo de OxígenoRESUMEN
The causes and consequences of excess exercise ventilation (EEV) in patients with fibrosing interstitial lung disease (f-ILD) were explored. Twenty-eight adults with f-ILD and 13 controls performed an incremental cardiopulmonary exercise test. EEV was defined as ventilation-carbon dioxide output (â©E-â©CO2) slope ≥36â¯L/L. Patients showed lower pulmonary function and exercise capacity compared to controls. Lower DLCO was related to higher â©E-â©CO2 slope in patients (P<0.05). 13/28 patients (46.4%) showed EEV, reporting higher dyspnea scores (P=0.033). Patients with EEV showed a higher dead space (VD)/tidal volume (VT) ratio while O2 saturation dropped to a greater extent during exercise compared to those without EEV. Higher breathing frequency and VT/inspiratory capacity ratio were observed during exercise in the former group (P<0.05). An exaggerated ventilatory response to exercise in patients with f-ILD is associated with a blunted decrease in the wasted ventilation in the physiological dead space and greater hypoxemia, prompting higher inspiratory constraints and breathlessness.
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Prueba de Esfuerzo , Ejercicio Físico , Enfermedades Pulmonares Intersticiales , Humanos , Enfermedades Pulmonares Intersticiales/fisiopatología , Femenino , Masculino , Persona de Mediana Edad , Anciano , Ejercicio Físico/fisiología , Ventilación Pulmonar/fisiología , Pruebas de Función Respiratoria , Volumen de Ventilación Pulmonar/fisiología , Disnea/fisiopatología , Tolerancia al Ejercicio/fisiologíaRESUMEN
Rationale: Ventilatory demand-capacity imbalance, as inferred based on a low ventilatory reserve, is currently assessed only at peak cardiopulmonary exercise testing (CPET). Peak ventilatory reserve, however, is poorly sensitive to the submaximal, dynamic mechanical ventilatory abnormalities that are key to dyspnea genesis and exercise intolerance. Objectives: After establishing sex- and age-corrected norms for dynamic ventilatory reserve at progressively higher work rates, we compared peak and dynamic ventilatory reserve for their ability to expose increased exertional dyspnea and poor exercise tolerance in mild to very severe chronic obstructive pulmonary disease (COPD). Methods: We analyzed resting functional and incremental CPET data from 275 controls (130 men, aged 19-85 yr) and 359 Global Initiative for Chronic Obstructive Lung Disease patients with stage 1-4 obstruction (203 men) who were prospectively recruited for previous ethically approved studies in three research centers. In addition to peak and dynamic ventilatory reserve (1 - [ventilation / estimated maximal voluntary ventilation] × 100), operating lung volumes and dyspnea scores (0-10 on the Borg scale) were obtained. Results: Dynamic ventilatory reserve was asymmetrically distributed in controls; thus, we calculated its centile distribution at every 20 W. The lower limit of normal (lower than the fifth centile) was consistently lower in women and older subjects. Peak and dynamic ventilatory reserve disagreed significantly in indicating an abnormally low test result in patients: whereas approximately 50% of those with a normal peak ventilatory reserve showed a reduced dynamic ventilatory reserve, the opposite was found in approximately 15% (P < 0.001). Irrespective of peak ventilatory reserve and COPD severity, patients who had a dynamic ventilatory reserve below the lower limit of normal at an isowork rate of 40 W had greater ventilatory requirements, prompting earlier attainment of critically low inspiratory reserve. Consequently, they reported higher dyspnea scores, showing poorer exercise tolerance compared with those with preserved dynamic ventilatory reserve. Conversely, patients with preserved dynamic ventilatory reserve but reduced peak ventilatory reserve reported the lowest dyspnea scores, showing the best exercise tolerance. Conclusions: Reduced submaximal dynamic ventilatory reserve, even in the setting of preserved peak ventilatory reserve, is a powerful predictor of exertional dyspnea and exercise intolerance in COPD. This new parameter of ventilatory demand-capacity mismatch may enhance the yield of clinical CPET in the investigation of activity-related breathlessness in individual patients with COPD and other prevalent cardiopulmonary diseases.
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Enfermedad Pulmonar Obstructiva Crónica , Masculino , Humanos , Femenino , Valores de Referencia , Pulmón , Disnea/etiología , Prueba de Esfuerzo , Tolerancia al EjercicioRESUMEN
BACKGROUND: Dysfunctional breathing (DB) is a common, but largely underappreciated, cause of chronic dyspnoea. Under visual inspection, most subjects with DB present with larger sequential changes in ventilation (VÌE) and breathing pattern (tidal volume (VT) and breathing frequency (f)) before and/or during incremental cardiopulmonary exercise testing (CPET). Currently, however, there are no objective criteria to indicate increased ventilatory variability in these subjects. METHODS: Twenty chronically dyspnoeic subjects with DB and 10 age- and sex-matched controls performed CPET on a cycle ergometer. Cut-offs to indicate increased VÌE, VT, f, and f/VT ratio variability (Δ = highest-lowest 20 s arithmetic mean) over the last resting minute (rest ), the 2sd min of unloaded exercise (unload ), and the 3rd min of loaded exercise (load ) were established by ROC curve analyses. RESULTS: Subjects with DB presented with increased VÌE, higher ventilatory variability, higher dyspnoea burden, and lower exercise capacity compared to controls (p < 0.05). ΔVÌEload (>4.1 L/min), Δfrest (>5 breaths/min; bpm), Δfunload (>4 bpm), Δfload (>5 bpm), Δf/VTrest (>4.9 bpm/L), and Δf/VTload (>1.3 bpm/L) differentiated DB from a normal pattern (areas under the curve ranging from 0.729 to 0.845). High Δf, in particular, was associated with DB across all CPET phases. CONCLUSIONS: This study provides objective criteria to indicate increased ventilatory variability during incremental CPET in dyspnoeic subjects with DB. Large variability in breathing frequency seems particularly useful in this context, a finding that should be prospectively confirmed in larger studies.
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Prueba de Esfuerzo , Respiración , Humanos , Pulmón , Disnea/diagnóstico , Volumen de Ventilación PulmonarRESUMEN
Oscillatory ventilation detected on incremental cardiopulmonary exercise testing might be found in subjects without heart failure reporting exertional dyspnoea despite the best available therapy for their underlying cardiopulmonary disease https://bit.ly/3Tyl7bE.
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BACKGROUND: Continuous monitoring of SpO2 throughout the 6-min walk test (6MWT) unveiled that some patients with respiratory diseases may present values across the test lower than SpO2 measured at the end of the test. Nevertheless, it remains unclear whether this approach improves the yield of walk-induced desaturation detection in predicting mortality and hospitalizations in patients with COPD. METHODS: Four hundred twenty-one subjects (51% males) with mild-very severe COPD underwent a 6MWT with continuous measurement of SpO2 . Exercise desaturation was defined as a fall in SpO2 ≥ 4%. All-cause mortality was assessed up to 6 y of follow-up and the rate of hospitalizations in the year succeeding the 6MWT. RESULTS: One hundred forty-nine subjects (35.4%) died during a mean (interquartile) follow-up of 55.5 (30.2-64.1) months. Desaturation was observed in 299/421 (71.0%). SpO2 along the test was < end SpO2 (88 [82-92]% vs 90 [84-93]%, P < .001). Desaturation detected only during (but not at the end of) the test was found in 81/421 (19.2%) participants. Multivariate Cox regression model adjusted for sex, body composition, FEV1, residual volume/total lung capacity ratio, walk distance, O2 supplementation during the test, and comorbidities retained the presence of desaturation either at the end (1.85 [95% CI 1.02-3.36]) or only along the test (2.08 [95% CI 1.09-4.01]) as significant predictors of mortality. The rate of hospitalizations was higher in those presenting with any kind of desaturation compared to those without exercise desaturation. Logistic regression analysis revealed that walking interruption and diffusing capacity of the lung for carbon monoxide predicted desaturation observed only during the test. CONCLUSIONS: O2 desaturation missed by end-exercise SpO2 but exposed by measurements during the test was independently associated with all-cause mortality and hospitalizations in subjects with COPD.
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Enfermedad Pulmonar Obstructiva Crónica , Masculino , Humanos , Femenino , Prueba de Paso , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Oxígeno , Prueba de Esfuerzo , Oximetría , CaminataRESUMEN
There is well established evidence that the minute ventilation (V'E)/carbon dioxide output (V'CO2 ) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V'E/V'CO2 reflects an enlarged physiological dead space ("wasted" ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V'E/V'CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1â s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V'E/V'CO2 is valuable to ascertain a role for the "lungs" in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V'E/V'CO2 A high V'E/V'CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V'E/V'CO2 should be valued in the clinical management of patients with COPD.
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Dióxido de Carbono , Enfermedad Pulmonar Obstructiva Crónica , Prueba de Esfuerzo , Tolerancia al Ejercicio , Humanos , Pulmón , Enfermedad Pulmonar Obstructiva Crónica/diagnóstico , Enfermedad Pulmonar Obstructiva Crónica/terapiaRESUMEN
BACKGROUND: Respiratory muscle unloading through proportional assist ventilation (PAV) may enhance leg oxygen delivery, thereby speeding off-exercise oxygen uptake ( V . ⢠O 2 ) kinetics in patients with heart failure with reduced left ventricular ejection fraction (HFrEF). METHODS: Ten male patients (HFrEF = 26 ± 9%, age 50 ± 13 years, and body mass index 25 ± 3 kg m2) underwent two constant work rate tests at 80% peak of maximal cardiopulmonary exercise test to tolerance under PAV and sham ventilation. Post-exercise kinetics of V . ⢠O 2 , vastus lateralis deoxyhemoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy, and cardiac output (Q T ) by impedance cardiography were assessed. RESULTS: PAV prolonged exercise tolerance compared with sham (587 ± 390 s vs. 444 ± 296 s, respectively; p = 0.01). PAV significantly accelerated V . ⢠O 2 recovery (τ = 56 ± 22 s vs. 77 ± 42 s; p < 0.05), being associated with a faster decline in Δ[deoxy-Hb + Mb] and Q T compared with sham (τ = 31 ± 19 s vs. 42 ± 22 s and 39 ± 22 s vs. 78 ± 46 s, p < 0.05). Faster off-exercise decrease in Q T with PAV was related to longer exercise duration (r = -0.76; p < 0.05). CONCLUSION: PAV accelerates the recovery of central hemodynamics and muscle oxygenation in HFrEF. These beneficial effects might prove useful to improve the tolerance to repeated exercise during cardiac rehabilitation.
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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 (ß = 25.366; R2 = 14%; p < 0.001), whereas DLCO predicted sleep onset latency (ß = -0.314; R2 = 13%; p < 0.001) and rapid eye movement sleep time/total sleep time in % (ß = 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.
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Enfermedad Pulmonar Obstructiva Crónica , Humanos , Pulmón , Polisomnografía , Estudios Retrospectivos , SueñoRESUMEN
This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls. In this study, 10 patients with ILD (mean age: 63.8 ± 9.2 years, forced expiratory volume in the first second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at different speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fluctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and significant oxygen desaturation during exercise. The CoT did not differ between the groups (p = 0.680), but dyspnea and SpO2 were higher and lower, respectively, in patients with ILD at the same relative speeds. SSWS was reduced in ILD patients (2.6 ± 0.9 vs. 4.2 ± 0.4 km h-1 p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was significantly lower in patients with ILD than in healthy controls, mainly at lower speeds. Patients with ILD presented a similar cost of transport compared to healthy controls; however, they chose lower SSWS despite higher walking energy expenditure. Although walking stability and dyspnea were negatively affected, these factors were not associated with the slower walking speed chosen by individuals with ILD.
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Disnea/fisiopatología , Metabolismo Energético/fisiología , Enfermedades Pulmonares Intersticiales/complicaciones , Velocidad al Caminar/fisiología , Anciano , Estudios de Casos y Controles , Disnea/etiología , Prueba de Esfuerzo , Voluntarios Sanos , Humanos , Enfermedades Pulmonares Intersticiales/fisiopatología , Masculino , Persona de Mediana Edad , Consumo de Oxígeno/fisiología , Pruebas de Función RespiratoriaRESUMEN
Several shortcomings on cardiopulmonary exercise testing (CPET) interpretation have shed a negative light on the test as a clinically useful tool. For instance, the reader should recognize patterns of dysfunction based on clusters of variables rather than relying on rigid interpretative algorithms. Correct display of key graphical data is of foremost relevance: prolixity and redundancy should be avoided. Submaximal dyspnea ratings should be plotted as a function of work rate (WR) and ventilatory demand. Increased work of breathing and/or obesity may normalize peak oxygen uptake (VÌO2) despite a low peak WR. Among the determinants of VÌO2, only heart rate is measured during non-invasive CPET. It follows that in the absence of findings suggestive of severe impairment in O2 delivery, the boundaries between inactivity and early cardiovascular disease are blurred in individual subjects. A preserved breathing reserve should not be viewed as evidence that "the lungs" are not limiting the subject. In this context, measurements of dynamic inspiratory capacity are key to uncover abnormalities germane to exertional dyspnea. A low end-tidal partial pressure for carbon dioxide may indicate either increased "wasted" ventilation or alveolar hyperventilation; thus, direct measurements of arterial (or arterialized) PO2 might be warranted. Differentiating a chaotic breathing pattern from the normal breath-by-breath noise might be complex if the plotted data are not adequately smoothed. A sober recognition of these limitations, associated with an interpretation report free from technicalities and convoluted terminology, is crucial to enhance the credibility of CPET in the eyes of the practicing physician.
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INTRODUCTION: Inspiratory muscle weakness (IMW) is a potential cause of exertional dyspnea frequently under-appreciated in clinical practice. Cardiopulmonary exercise testing (CPET) is usually requested as part of the work-up for unexplained breathlessness, but the specific pattern of exercise responses ascribed to IMW is insufficiently characterized. OBJECTIVES: To identify the physiological and sensorial responses to progressive exercise in dyspneic patients with IMW without concomitant cardiorespiratory or neuromuscular diseases. METHODS: Twenty-three subjects (18 females, 55.2 ± 16.9 years) complaining of chronic daily life dyspnea (mMRC = 3 [2-3]) plus maximal inspiratory pressure < the lower limit of normal and 12 matched controls performed incremental cycling CPET. FEV1/FVC<0.7, significant abnormalities in chest CT or echocardiography, and/or an established diagnosis of neuromuscular disease were among the exclusion criteria. RESULTS AND CONCLUSION: Patients presented with reduced aerobic capacity (peak VÌO2: 79 ± 26 vs 116 ± 21 %predicted), a tachypneic breathing pattern (peak breathing frequency/tidal volume = 38.4 ± 22.7 vs 21.7 ± 14.2 breaths/min/L) and exercise-induced inspiratory capacity reduction (-0.17 ± 0.33 vs 0.10 ± 0.30 L) (all P < .05) compared to controls. In addition, higher ventilatory response (ΔVÌE/ΔVÌCO2 = 34.1 ± 6.7 vs 27.0 ± 2.3 L/L) and symptomatic burden (dyspnea and leg discomfort) to the imposed workload were observed in patients. Of note, pulse oximetry was similar between groups. Reduced aerobic capacity in the context of a tachypneic breathing pattern, inspiratory capacity reduction and preserved oxygen exchange during progressive exercise should raise the suspicion of inspiratory muscle weakness in subjects with otherwise unexplained breathlessness.