First Evaluation of a Transcutaneous Carbon Dioxide Monitoring Wristband Device during a Cardiopulmonary Exercise Test.

Decision letter: VO2max prediction based on submaximal cardiorespiratory relationships and body composition in male runners and cyclists: a population study

Cardiopulmonary exercise (CPX) testing has a number of medical applications, including the assessment of heart failure and the investigation of unexplained breathlessness. Over the past decade, it has become an important preoperative assessment tool to evaluate functional capacity and predict outcomes in patients undergoing both cardiac and noncardiac surgery. A CPX test is an incremental exercise test during which respiratory variables, including oxygen uptake and carbon dioxide excretion are measured and the ECG is monitored. Among the variables reported from a CPX test are oxygen uptake at anaerobic threshold and peak oxygen uptake. A limited functional capacity as indicated by a low anaerobic threshold or VO(2peak) has been shown to be associated with an increased incidence of perioperative complications in a number of surgical settings. Other reported variables, including the ventilatory equivalents for oxygen (VE/VO(2)) and carbon dioxide (VE/VCO(2)) and the millilitre of oxygen delivered per heartbeat or oxygen pulse [VO(2)/heart rate (HR)] may give indications as to the reasons for exercise limitation. ECG evidence of myocardial ischaemia with increasing workload is also an important indicator of increased perioperative risk. As a noninvasive, low-risk, test of the integrated responses to increasing cardiovascular stress, anaesthesiologists involved in preoperative assessment should have an understanding of its current uses and test outcomes. This review presents the physiological basis for CPX testing, methodology, advantages over other preoperative tests of cardiovascular function and guidance on the interpretation of CPX results in the perioperative setting.

Gender Differences in Leptin and Ventilatory Control in Patients with Heart Failure

This study aimed to determine the glycemic responses to cardiopulmonary exercise testing (CPET) in individuals with type 1 diabetes (T1D) and to explore the influence of starting blood glucose (BG) concentrations on subsequent CPET outcomes. This study was a retrospective, secondary analysis of pooled data from three randomized crossover trials using identical CPET protocols. During cycling, cardiopulmonary variables were measured continuously, with BG and lactate values obtained minutely via capillary earlobe sampling. Anaerobic threshold was determined using ventilatory parameters. Participants were split into (i) euglycemic ([Eu] >3.9 to ≤10.0 mmol·L-1, n = 26) and (ii) hyperglycemic ([Hyper] >10.0 mmol·L-1, n = 10) groups based on preexercise BG concentrations. Data were assessed via general linear modeling techniques and regression analyses. P values of ≤0.05 were accepted as significant. Data from 36 individuals with T1D (HbA1c, 7.3% ± 1.1% [56.0 ± 11.5 mmol·mol-1]) were included. BG remained equivalent to preexercise concentrations throughout CPET, with an overall change in BG of -0.32 ± 1.43 mmol·L-1. Hyper had higher HR at peak (+10 ± 2 bpm, P = 0.04) and during recovery (+9 ± 2 bpm, P = 0.038) as well as lower O2 pulse during the cool down period (-1.6 ± 0.04 mL per beat, P = 0.021). BG responses were comparable between glycemic groups. Higher preexercise BG led to greater lactate formation during exercise. HbA1c was inversely related to time to exhaustion (r = -0.388, P = 0.04) as well as peak power output (r = -0.355, P = 0.006) and O2 pulse (r = -0.308, P = 0.015). This study demonstrated 1) stable BG responses to CPET in patients with T1D; 2) although preexercise hyperglycemia did not influence subsequent glycemic dynamics, it did potentiate alterations in various cardiac and metabolic responses to CPET; and 3) HbA1c was a significant factor in the determination of peak performance outcomes during CPET.

Cardiopulmonary exercise testing (CPET) is a unique diagnostic tool that assesses the functional capacity of the heart, lungs, and peripheral oxidative system in an integrated manner. However, the clinical utility of CPET for evaluating interstitial lung disease (ILD) remains uncertain. The objective of this study was to determine the predictive value of CPET for mortality in subjects with ILD. We prospectively enrolled subjects with ILD who underwent CPET at a tertiary medical center in Taiwan and followed up their survival status for 12 months. Mortality prediction was based on comparing CPET parameters between subjects who survived and those who died. We further analyzed CPET parameters that showed significant differences using receiver operating characteristic curves to identify their optimal cutoff values. A total of 106 newly diagnosed subjects with ILD underwent CPET, and the 1-y mortality rate was 7.5%. Six CPET variables were found to be significant predictors of mortality: peak oxygen consumption, oxygen pulse, end-tidal partial pressure of carbon dioxide, heart rate recovery 1 min after CPET, minute ventilation to carbon dioxide output slope, and functional aerobic impairment. We calculated a summed score by adding the number of CPET variables that exceeded their cutoff values. Subjects with a summed score of 6 had a 1-y survival rate of only 25%, whereas subjects with scores of 0-5 had a survival rate of 98%. In conclusion, the summed score represents a useful tool for screening patients with ILD who can undergo a CPET to determine their prognosis.

Gas exchange measurements, such as oxygen uptake ( ) and carbon dioxide output ( ), of cardiopulmonary exercise testing (CPET), are the key and gold standard for human cardiopulmonary functional evaluation. However, in terms of quality control, they are unstable and inaccurate. We used a metabolic simulator (MS) to detect measurement errors and enhance quality control. In the Fuwai CPET laboratory, we performed CPET after systems had: (I) passed all the steps of regular system calibrations for flow and the partial pressure of O2 and CO2; and (II) passed the MS validation of and at low, medium, and high metabolic rates (MRs) daily from 2014 to 2023 for eight different CPET carts/systems. The absolute percentage difference of the 1st validation of both and was calculated as follows: |[(measured - ideal) / ideal] × 100%|. A difference of <10% was set as the 1st validation pass standard to run the laboratory, while a difference of ≥10% was classified as a 1st validation failure. The absolute percentage difference of the 1st validation among the eight carts/systems was compared using the Kruskal-Wallis H test. The rate of the 1st validation failure, the number of validation days, and the median absolute percentage difference of the 1st validation among the different CPET carts/systems were clustered using the hierarchical clustering method. In total, we completed 1,810 validation days for the eight CPET carts/systems, and found a 10,860 absolute percentage difference of the 1st validation of and . The number of validation days completed by each cart/system and the 1st validation failure rates were as follows: 8 (87.50%), 10 (90.00%), 54 (48.15%), 349 (43.27%), 20 (45.00%), 759 (21.21%), 525 (29.52%), and 85 (22.35%), respectively. The overall absolute percentage difference of the 1st validation of each cart/system was 7.32% (P25, P75: 3.67%, 13.82%), 9.12% (P25, P75: 3.33%, 30.4%), 6.82% (P25, P75: 4.31%, 9.06%), 5.40% (P25, P75: 2.60%, 8.26%), 4.90% (P25, P75: 2.21%, 9.68%), 4.32% (P25, P75: 2.17%, 6.78%), 5.62% (P25, P75: 2.96%, 8.19%), and 5.35% (P25, P75: 2.55%, 7.81%), respectively. The Kruskal-Wallis H test results revealed significant differences among the eight carts/systems (H=274.86, P<0.001), and the pairwise comparisons showed that cart/system F had the lowest absolute percentage difference of 4.32% (P25, P75: 2.17%, 6.78%). The hierarchical cluster classified carts/systems A and B as one cluster, carts/systems C, E, and H as another cluster, and carts/systems D, F, and G as yet another cluster. Using an MS can decrease measurement errors and variability for CPET. It can also improve the quality control of CPET.

Cardiopulmonary exercise testing (CPET) is a dynamic clinical tool for determining the cause for a person's exercise limitation. CPET provides clinicians with fundamental knowledge of the coupling of external to internal respiration (oxygen and carbon dioxide) during exercise. Subtle perturbations in CPET parameters can differentiate exercise responses among individual patients and disease states. However, perhaps because of the challenges in interpretation given the amount and complexity of data obtained, CPET is underused. In this article, we review fundamental concepts in CPET data interpretation and visualization. We also discuss future directions for how to best use CPET results to guide clinical care. Finally, we share a novel three-dimensional graphical platform for CPET data that simplifies conceptualization of organ system-specific (cardiac, pulmonary, and skeletal muscle) exercise limitations. Our goal is to make CPET testing more accessible to the general medical provider and make the test of greater use in the medical toolbox.

Objective: To study the symptom-restricted extreme cardiopulmonary exercise testing (CPET) to evaluate the improvement of the overall function of patients with long-term chronic diseases after intensive control of personalized precise exercise training for 3 months. Methods: We selected 20 patients with chronic cardiovascular and cerebrovascular metabolic diseases who were intensively controlled by our team from 2014 to 2016. After signing the informed consent form, based on the results of CPET and continuous functional tests, we formulated the overall management plan with individualized moderate exercise intensity as the core. After 3 months, CPET was performed. The changes of CPET indicators before and after intensive control in each patient were analyzed individually. Then the difference value and percentage difference value were calculated. Results: In this study, 20 patients (18 males and 2 females) with chronic cardiovascular and cerebrovascular metabolic diseases, aged (55.75±10.80, 26~73) years, height (172.20±8.63, 153~190) cm, weight (76.35±15.63, 53~105) kg, all patients were not any dangerous events during the period of CPET and intensive control.①After intensive control, the static pulmonary function index, resting systolic blood pressure, rate blood pressure product and fasting blood glucose were significantly improved (P<0.05).②Before intensive control, the peak oxygen uptake is (55.60±15.69, 34.37~77.45) % pred and anaerobic threshold is (60.11±12.26, 43.29~80.63)% pred; after intensive control, the peak oxygen uptake is (71.85±21.04, 42.40~102.00) % pred and anaerobic threshold (74.95±17.03, 51.90~99.47) %pred. Compared with before the intensive control, the peak oxygen uptake and anaerobic threshold of all patients after intensive control were significantly increased by (29.09±7.38,17.78~41.80) % and(25.16±18.38, 1.77~81.86)%(all P<0.01). Other core indexes were also improved significantly, including peak oxygen uptake,peak heart rate, peak work rate, oxygen uptake efficiency plateau, lowest value of carbon dioxide ventilatory efficiency, slope of ventilatory equivalent for carbon dioxide, ramp exercise duration(all P<0.01).③In terms of individualized analysis, after intensive control, the above 8 CPET core indexes were all improved in 15 cases, and 7 indexes in 5 cases were improved; the peak oxygen uptakeof all cases increased by more than 15%, 16 cases > 20%, 13 cases > 25%, 10 cases > 30%. Conclusion: CPET can safely, objectively and quantitatively evaluate the overall functional status and therapeutic effects, and guide the formulation of individualized precise exercise intensity. The overall plan of individualized precision exercise for three months can safely and effectively reverse the overall functional status of patients with long-term cardio-cerebrovascular metabolism diseases.

Cardiopulmonary Exercise Test Could Predict Mortality in Patients with Interstitial Lung Disease

Inert gas rebreathing has been recently described as an emergent reliable non-invasive method for cardiac output determination during exercise, allowing a relevant improvement of cardiopulmonary exercise test clinical relevance. For cardiac output measurements by inert gas rebreathing, specific respiratory manoeuvres are needed which might affect pivotal cardiopulmonary exercise test parameters, such as exercise tolerance, oxygen uptake and ventilation vs carbon dioxide output (VE/VCO2) relationship slope. We retrospectively analysed cardiopulmonary exercise testing of 181 heart failure patients who underwent both cardiopulmonary exercise testing and cardiopulmonary exercise test+cardiac output within two months (average 16 ± 15 days). All patients were in stable clinical conditions (New York Heart Association I-III) and on optimal medical therapy. The majority of patients were in New York Heart Association Class I and II (78.8%), with a mean left ventricular ejection fraction of 31 ± 10%. No difference was found between the two tests in oxygen uptake at peak exercise (1101 (interquartile range 870-1418) ml/min at cardiopulmonary exercise test vs 1103 (844-1389) at cardiopulmonary exercise test-cardiac output) and at anaerobic threshold. However, anaerobic threshold and peak heart rate, peak workload (75 (58-101) watts and 64 (42-90), p < 0.01) and carbon dioxide output were significantly higher at cardiopulmonary exercise testing than at cardiopulmonary exercise test+cardiac output, whereas VE/VCO2 slope was higher at cardiopulmonary exercise test+cardiac output (30 (27-35) vs 33 (28-37), p < 0.01). The similar anaerobic threshold and peak oxygen uptake in the two tests with a lower peak workload and higher VE/VCO2 slope at cardiopulmonary exercise test+cardiac output suggest a higher respiratory work and consequent demand for respiratory muscle blood flow secondary to the ventilatory manoeuvres. Accordingly, VE/VCO2 slope and peak workload must be evaluated with caution during cardiopulmonary exercise test+cardiac output.

Effects of 100 % oxygen during exercise in patients with interstitial lung disease

Anaerobic threshold: pitfalls and limitations

Objective: To observe the effect of healthy volunteers different work rate increasing rate cardiopulmonary exercise testing (CPET) on the sub-peak parameters . Methods: Twelve healthy volunteers were randomly assigned to a moderate (30 W/min), a relatively low (10 W/min) and relatively high (60 W/min) three different work rate increasing rate CPET on different working days in a week. The core indicators related to CPET sub-peak exercise of 12 volunteers were compared according to standard Methods: anaerobic threshold (AT), oxygen uptake per unit power (ΔVO2/ΔWR), oxygen uptake eficiency plateau,（OUEP), the lowest average of 90 s of carbon dioxide ventilation equivalent (Lowest VE/ VCO2), the slope of carbon dioxide ventilation equivalent (VE/ VCO2 Slope) and intercept and anaerobic threshold oxygen uptake ventilation efficiency value (VO2/ VE@AT) and the anaerobic threshold carbon dioxide ventilation equivalent value (VE/ VCO2@AT). Paired t test was performed on the difference of each parameter in the three groups of different work rate increasing rate. Results: Compared with the relatively low and relatively high work rate increasing rate group, the moderate work rate increasing rate group uptake eficiency plateau, (42.22±4.76 vs 39.54±3.30 vs 39.29±4.29) and the lowest average of 90 s of carbon dioxide ventilation equivalent (24.13±2.88 vs 25.60±2.08 vs 26.06±3.05) was significantly better, and the difference was statistically significant (P<0.05); Compared with the moderate work rate increasing rate group, the oxygen uptake per unit work rate of the relatively low and relatively high work rate increasing rate group increased and decreased significantly ((8.45±0.66 vs 10.04±0.58 vs 7.16±0.60) ml/(min·kg)), difference of which was statistically significant (P<0.05); the anaerobic threshold did not change significantly ((0.87±0.19 vs 0.87±0.19 vs 0.89±0.19) L/min), the difference was not statistically significant (P>0.05). Conclusion: Relatively low and relatively high power increase rate can significantly change the CPET sub-peak sports related indicators such as the effectiveness of oxygen uptake ventilation, the effectiveness of carbon dioxide exhaust ventilation, and the oxygen uptake per unit work rate. Compared with the moderate work rate increasing rate CPET, the lower and higher work rate increasing rate significantly reduces the effectiveness of oxygen uptake ventilation and the effectiveness of carbon dioxide exhaust ventilation in healthy individuals. The standardized operation of CPET requires the selection of a work rate increasing rate suitable for the subject, so that the CPET sub-peak related indicators can best reflect the true functional state of the subject.

Cardiopulmonary exercise testing (CPET) may capture potential impacts of COVID-19 during exercise. We described CPET data on athletes and physically active individuals with or without cardiorespiratory persistent symptoms. Participants' assessment included medical history and physical examination, cardiac troponin T, resting electrocardiogram, spirometry and CPET. Persistent symptoms were defined as fatigue, dyspnea, chest pain, dizziness, tachycardia, and exertional intolerance persisting >2 months after COVID-19 diagnosis. A total of 46 participants were included; sixteen (34.8%) were asymptomatic and thirty participants (65.2%) reported persistent symptoms, with fatigue and dyspnea being the most reported ones (43.5 and 28.1%). There were a higher proportion of symptomatic participants with abnormal data for slope of pulmonary ventilation to carbon dioxide production (VE/VCO2 slope; p<0.001), end-tidal carbon dioxide pressure at rest (PETCO2 rest; p=0.007), PETCO2 max (p=0.009), and dysfunctional breathing (p=0.023) vs. asymptomatic ones. Rates of abnormalities in other CPET variables were comparable between asymptomatic and symptomatic participants. When assessing only elite and highly trained athletes, differences in the rate of abnormal findings between asymptomatic and symptomatic participants were no longer statistically significant, except for expiratory air flow-to-percent of tidal volume ratio (EFL/VT) (more frequent among asymptomatic participants) and dysfunctional breathing (p=0.008). A considerable proportion of consecutive athletes and physically active individuals presented with abnormalities on CPET after COVID-19, even those who had had no persistent cardiorespiratory symptomatology. However, the lack of control parameters (e.g., pre-infection data) or reference values for athletic populations preclude stablishing the causality between COVID-19 infection and CPET abnormalities as well as the clinical significance of these findings.

Introduction Pulmonary arterial hypertension (PAH) is a rare form of pulmonary hypertension (PH) that may also be associated with connective tissue diseases (CTD). In particular, PAH may affect from 5 to 19% of patients with systemic sclerosis (SSc), leading to a significant prognostic worsening. The current challenge is an early detection of PAH in such patients, in order to provide an early referral to PH centers to supply specific therapies as soon as possible. In the latest ESC guidelines for PH, cardiopulmonary exercise testing (CPET) has been included in the diagnostic algorithm for patients with unexplained exertional dyspnoea and/or suspected PH. Patients with PAH show a typical pattern, with a low end-tidal partial pressure of carbon dioxide (PETCO2), high ventilatory equivalent for carbon dioxide (VE/VCO2), low oxygen pulse (VO2/ HR) and low peak oxygen uptake (VO2). CPET may identify patients with SSc at low risk of PAH, to avoid unnecessary right heart catheterization (RHC). However, CPET is not available in all centers. So, we designed a preliminary study to identify new biomarkers that correlate with CPET's parameters. Material and Methods We enrolled 62 SSc patients [53 females, median age 52 years] with no other comorbidities and asymptomatic for dyspnea or other symptoms. 56% and 44% of them presented limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc), respectively. For all patients we performed serum analysis for sST2, Galectine-3, pro-ANP, BNP and IL6, diagnostic imaging with echocardiography and cardiac MRI, CPET and pulmonary functionality test (PFT). Results All patients presented normal echocardiographic and RMI imaging findings. Galectin-3, sST2, pro-ANP, BNP and IL6 presented respectively the following median value: 13.45 ng/mL [11.78; 18.70], 23.25 ng/mL [13.04; 43.35], 1897 fmol/ml [1487; 2445], 12.18 pg/mL [9.34; 15.01]. Both Galectin-3 and sST2 showed a linear correlation with VE/VCO2 slope with R 0.339 (P-value 0.018) and 0.355 (P-value 0.013) respectively. After linear regression analysis, Galectin-3 and sST2 were overall statistically significant with R2 of 0.115 and 0.126, F of 5.97 and 6.62 and P-value of 0.018 and 0.013, respectively. It was found that Galectin-3 and SST2 significantly predicted VE/VCO2 slope with β = 0.364 [0,064; 0,665] for Galectin-3 and 0.137 [0,030; 0,244] for SST2. All other CPET parameters did not show correlation with the biomarkers. Conclusion Our preliminary results suggest that Galectine-3 and sST2 may be useful biomarkers for predicting increasing VE/VCO2 slope. Future analysis may confirm the role of these new biomarkers for early detection of pulmonary vascular involvement in SSc patients to allow an early referral and treatment and, conversely, to avoid unnecessary RHC.