Search

Exercise‐induced laryngeal obstruction (EILO) is common, but we lack readily available diagnostic tools. The larynx represents an important point of resistance in the airways, and we therefore hypothesized that EILO is associated with characteristic breathing patterns possible to record from a standard incremental ergospirometry test. We studied 24 individuals with moderate/severe EILO and 20 individuals with no‐EILO, mean (SD) age 17 (6.1) and 24 (6.4) years, respectively. EILO versus no‐EILO was verified from maximal continuous laryngoscopy treadmill exercise (CLE) tests, which also included ergospirometry. We described the relationships between minute ventilation (V˙E) versus tidal volume (V T) and V˙E versus carbon dioxide output (V˙CO2), using respectively quadratic and linear equations, and applied adjusted regression models to compare ergospirometry data and curve parameters. Compared to the no‐EILO group, the group with EILO had prolonged inspiratory time (T in), lower breathing frequency (B f), lower V˙E, and lower inspiratory flow rate (V˙in) at peak exercise. Mathematical modeling of the breathing pattern relationships was feasible in both groups, with similar coefficients of variation. For V˙E versus V T, the mathematical curve parameters were similar. For V˙E versus V˙CO2, the slope was similar but the intercept was lower in the EILO group. EILO was associated with prolonged T in, lower B f, V˙E, and V˙E. The relationship between V˙E versus V T was similar, whereas for V˙E versus V˙CO2, the slope was almost parallel but shifted downward for the EILO group. Most ergospirometry data overlapped, except V˙in which discriminated between EILO and no‐EILO in a promising way., EILO was associated with prolonged T in, lower B f, V˙E, and V˙in. The relationship between V˙E versus V T was similar, whereas for V˙E versus V˙CO2. Most ergospirometry data overlapped, except V˙in which discriminated between EILO and no‐EILO in a promising way.

Introduction Coronavirus disease 2019 (COVID-19) is a highly pathogenic coronavirus characterized by by systemic inflammatory response with endothelial damage and a dysregulated coagulation system. Despite most patients survive the acute setting of COVID-19, their long-term clinical sequelae are highly unclear. We have sought to identify the impact of post-COVID-19 syndrome on mid-term follow-up and gain some additional insights about the potential explanation for persistence of dyspnea. Methods This is a 3-month prospective cohort study of previously hospitalised COVID-19 patients recruited from a single Spanish center, a small outpatient group without prior hospitalisation was also evaluated. Patients underwent serial testing with cardio-pulmonary exercise test (CPET), transthoracic echocardiogram, pulmonary lung test, six-minute walking test, serum biomarker analysis and quality of life questionaries. They were classify according to the presence of persistent dyspnea. Primary study outcome was predicted peak oxygen consumption (V02) according to CPET and predicted carbon monoxide diffusion capacity. Results Our study included 41 (58.6%) patients with dyspnea and 29 (41.4%) asymptomatic. Symptomatic patients had a higher proportion of females (73.2% vs. 51.7%), but comparable age and prevalence of cardiovascular risk factors. We did not observe differences among the assessed variables in transthoracic echocardiogram and pulmonary function test. Patients who referred dyspnea had smaller predicted peak O2 consumption (77.8 [64–92.5] vs. 99 [88–105]: p Interpretation In this study >50% of COVID-19 survivors present a symptomatic functional impairment irrespective of age or prior hospitalization. Compared to asymptomatic patients, among those who referred dyspnea our findings suggest potential ventilatory inefficiency. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Gerencia Regional de Salud de Castilla y Leόn; Grant from the Spanish Society of Cardiology Tabla de resultados

Background Obstructive sleep apnea (OSA) is a chronic disorder that results in many cardiovascular disorders including hypertension, arrhythmias and congestive heart failure (CHF). Polysomnography is the gold standard for diagnosis of OSA, even though up to 93% of women and 82% of men with moderate to severe OSA still remain undiagnosed. Cardiopulmonary exercise testing (CPXT) has been conventionally used for evaluation of coronary artery diseases and rehabilitation of cardiac patients. Modern systems allow for the analysis of gas exchange at rest, during exercise, and during recovery and also yield measures of oxygen uptake (V O2), carbon dioxide output (V CO2), and minute ventilation (V E) together with heart rate, blood pressure, electrocardiography findings, and symptoms. This may have clinical utility if added to the available screening tools used to identify OSA. Aim of study To assess altered ventilatory response and heart rate recovery in response to exercise in patients with obstructive sleep apnea and their relation to its severity. Methods and Results Case control study was enrolled including 30 patients with obstructive sleep apnea (OSA) divided according to severity (5 mild, 8 moderate and 17 severe) and 15 control healthy overweight with sedentary lifestyle individuals. The two groups underwent cardiopulmonary exercise testing and different pulmonary and cardiac parameters were calculated. Greater VE, VE/VCO2, VE/VO2 ratios and VE/VCO2 slope were statistically significant regarding the patients group (P Conclusion Patients with OSA demonstrated exaggerated ventilatory response to exercise and autonomic dysfunction reflected by measurement of heart rate variability and reduced maximal exercise capacity than healthy controls. Abbreviations OSA, CHF, CPXT, VO2, VCO2, VE, VE/VCO2, VE/VO2, VE/VCO2, BR, CR, HRR, max SBP and max DBP.

Background Chronic obstructive pulmonary disease (COPD) augments the likelihood of having left ventricular diastolic dysfunction (LVDD) – precursor of heart failure with preserved ejection fraction (HFpEF). LVDD shares overlapping symptomatology (cough and dyspnea) with COPD. Purpose Our aim was to evaluate the predictive value of inflammatory, oxidative stress, cardio-pulmonary and echocardiographic parameters at rest for the diagnosis of stress LVDD in non-severe COPD patients, who complain of exertional dyspnea and are free of overt cardiovascular diseases. Methods A total of 104 COPD patients underwent echocardiography before cardio-pulmonary exercise testing (CPET) and 1–2 minutes after peak exercise. Patients were divided into two groups based on peak E/e': patients with stress induced left ventricular diastolic dysfunction (LVDD) - E/e' >15 (HFpEF) and patients LVDD (without HFpEF). CPET and echocardiographic parameters at rest were measured and their predictive value for stress E/e' was analysed. Markers for inflammation (resistin, prostaglandine E2) and oxidative stress (8-isoprostanes) were also determined. Results Stress induced LVDD occurred in 67/104 patients (64%). Those patients had lower work load, lower VO2 consumption, lower minute ventilation and higher VE/VCO2 slope in comparison to patients without. Except for prostglandine E2, none of the inflammatory, oxidative stress markers correlated to stress E/e'. The best independent predictors for HFpEF were RAVI, right ventricular parasternal diameter and RV E/A >0.75. Their combination predicted HFpEF with the accuracy of 91.2%. Conclusion There is a high prevalence of HFpEF in non-severe COPD with exertional dyspnea, free of overt cardiovascular disease. RAVI, right ventricular parasternal diameter and RV E/A >0.75 were the only independent clinical predictors of HFpEF. Funding Acknowledgement Type of funding sources: None.

Background A specific walking speed minimizing the U-shaped relationship between energy cost of transport per unit distance (CoT) and speed is called economical speed (ES). To investigate the effects of reduced body weight on the ES, we installed a body weight support (BWS) apparatus with a spring-like characteristics. We also examined whether the 'calculated' ES was equivalent to the 'preferred' walking speed (PWS) with 30% BWS. Methods We measured oxygen uptake and carbon dioxide output to calculate CoT values at seven treadmill walking speeds (0.67–2.00 m s− 1) in 40 healthy young males under normal walking (NW) and BWS. The PWS was determined under both conditions on a different day. Results A spring-like behavior of our BWS apparatus reduced the CoT values at 1.56, 1.78, and 2.00 m s− 1. The ES with BWS (1.61 ± 0.11 m s− 1) was faster than NW condition (1.39 ± 0.06 m s− 1). A Bland-Altman analysis indicated that there were no systematic biases between ES and PWS in both conditions. Conclusions The use of BWS apparatus with a spring-like behavior reduced the CoT values at faster walking speeds, resulting in the faster ES with 30% BWS compared to NW. Since the ES was equivalent to the PWS in both conditions, the PWS could be mainly determined by the metabolic minimization in healthy young males. This result also derives that the PWS can be a substitutable index of the individual ES in these populations.

Purpose The portable metabolic analyzer COSMED K5 (Rome, Italy) allows for switching between breath-by-breath (BBB) and dynamic micro-mixing chamber (DMC) modes. This study aimed to evaluate the reliability and validity of the K5 in BBB and DMC at low, moderate, and high metabolic rates. Methods Two K5 simultaneously operated in BBB or DMC, whereas (i) a metabolic simulator (MS) produced four different metabolic rates (repeated eight times), and (ii) 12 endurance-trained participants performed bike exercise at 30%, 40%, 50%, and 85% of their individual power output at V˙O2max (repeated three times). K5 data were compared with predicted simulated values and consecutive Douglas bag measurements. Results Reliability did not differ significantly between BBB and DMC, whereas the typical error and intraclass correlation coefficients for oxygen uptake (V˙O2), carbon dioxide output (V˙CO2), and minute ventilation (V˙E) ranged from 0.27% to 6.18% and from 0.32 to 1.00 within four metabolic rates, respectively. Validity indicated by mean differences ranged between 0.61% and -2.05% for V˙O2, 2.99% to -11.04% for V˙CO2, and 0.93% to -6.76% for V˙E compared with MS and Douglas bag at low to moderate metabolic rates and was generally similar for MS and bike exercise. At high rates, mean differences for V˙O2 amounted to -4.63% to -7.27% in BBB and -0.38% to -3.81% in DMC, indicating a significantly larger difference of BBB at the highest metabolic rate. Conclusion The K5 demonstrated accurate to acceptable reliability in BBB and DMC at all metabolic rates. Validity was accurate at low and moderate metabolic rates. At high metabolic rates, BBB underestimated V˙O2, whereas DMC showed superior validity. To test endurance athletes at high workloads, the DMC mode is recommended.

The lumbar-type Hybrid Assistive Limb (HAL) is expected to expand the possibilities of exercise therapy for severe cardiac patients who have difficulty in moving on their own legs. We investigated whether motion assistance from HAL during squat exercise could effectively reduce the cardiopulmonary burden in healthy subjects. Twelve healthy subjects (33 ± 11 years) performed squat exercise for 3 consecutive minutes at a repetition rate of 20 squats per minute with and without assistance from a lumbar-type HAL. The oxygen uptake (VO2), carbon dioxide output (VCO2), minute ventilation (VE), and the Borg Scale were monitored during exercise. VO2 (930 ± 207 vs 992 ± 169 mL/min, p 0.05) and the Borg Scale rating (12.8 ± 1.1 vs 13.7 ± 0.8, p 0.05) at the end of exercise were significantly lower when HAL was used. When 2 subjects who regularly perform high-intensity exercise for more than 10 h per week were excluded from the analyses, VO2, VCO2, VE, and the Borg Scale were significantly lower when HAL was used. Our results demonstrate that the lumbar-type HAL significantly reduces cardiopulmonary burden during squat exercise in healthy subjects. The effects were especially striking in sedentary subjects. Further studies on cardiac patients are expected to establish a new cardiac rehabilitation program using HAL.

Funding Acknowledgements Type of funding sources: None. Introduction Cardiopulmonary exercise testing (CPET) is used for risk stratification in patients with chronic heart failure (CHF). However, there is a lack of information regarding CPET prognostic power in patients under new HF therapies such as sacubitril/valsartan, Mitraclip, IV iron or SGLT2 inhibitors. The aim of this study was to evaluate the prognostic value of CPET parameters in a contemporary subset of patients with optimal medical and device therapy for CHF. Methods Retrospective evaluation of patients with CHF submitted to CPET in a tertiary center. Patients were followed up for 24 months for the composite endpoint of cardiac death, urgent heart transplantation or left ventricular assist device. CPET parameters, including peak oxygen consumption (pVO2) and VE/VCO2 slope, were analysed and their predictive power was measured. HF events were stratified according to cut-off values defined by the International Society for Heart and Lung Transplantation (ISHLT) guidelines: pVO2 of ≤12 mL/Kg/min and VE/VCO2 slope of >35. Results CPET was performed in 204 patients, from 2014 to 2018. Mean age was 59 ± 13 years, 83% male, with a mean left ventricular ejection fraction of 33 ± 8%, and a mean Heart Failure Survival Score of 8.6 ± 1.3. The discriminative power of CPET parameters is displayed in the Table. In patients with pVO2 ≤12 mL/Kg/min, the composite endpoint occurred in 18% of patients. A pVO2 value of ≤12 mL/Kg/min had a positive predictive power of 18% while pVO2 >12 had a negative predictive power of 93%. Regarding VE/VCO2 slope >35, the composite endpoint occurred in 13% of patients. A VE/VCO2 slope value of >35 had a positive predictive power of 13% while VE/VCO2 slope Conclusion Using ISHLT guideline cut-off values for advanced HF therapies patient selection, there was a reduced number of HF events ( Discriminative power of CPET parameters Parameters HR; 95% CI AUC p-value Peak VO2 0.824 (0.728-0.934) 0.781 0.001 Percent of predicted pVO2 0.942 (0.907-0.978) 0.774 0.002 VE/VCO2 slope 1.068 (1.031-1.106) 0.756 0.008 Cardiorespiratory optimal point 1.118 (1.053-1.188) 0.746 0.004 PETCO2 maximum exercise 0.854 (0.768-0.950) 0.775 0.003 Ventilatory Power 0.358 (0.176-0.728) 0.796 0.002 HR Hazard ratio, AUC: Area under the curve, PETCO2: end-tidal CO2 pressure

Funding Acknowledgements Type of funding sources: None. Background Cardiopulmonary exercise testing (CPX) is established in the evaluation of patients with cardiac and pulmonary diseases, and its clinical utility seems to be expanding. Currently the most important diagnostic and prognostic ventilatory metrics of CPX rely on the exercise phase. Nevertheless, a consistent body of evidence suggests that important information can be derived from the recovery phase, especially in the first few minutes after exercise. In this context, patients with heart failure (HF) demonstrate a slower recovery of the oxygen consumption (VO2) compared with healthy individuals. Purpose: To comprehensively investigate the behavior of respiratory gases during recovery from CPX in a diverse cohort of HF patients. Methods: All individuals who performed CPX at the department of cardiology of Stanford University Hospital were eligible for the study. Patients were included in the experimental group if they (i) were recorded for five minutes after the exercise phase of CPX and (ii) had documented heart failure. They were excluded if they had other clinical diagnoses which may be responsible for exercise intolerance or symptoms or were unable to give informed consent. Healthy controls were recruited from the local community and were included if they did not have documented or suspected disease. Respiratory gases were collected on a breath-by-breath basis and analysed after applying a 30 second rolling average filter. Metrics were analyzed as absolute values, percentage change from peak and the half-time of recovery (T ½; i.e. the duration until a metric had returned to ½ of its value at peak). Data was analyzed over time within patients and averages between groups using parametric statistical methods. In accordance with previous studies, the amount of change in a metric after exercise is presented as the "magnitude" of overshoot. Results: 32 patients with HF (11 Female, 47 ± 13 yrs) and 30 healthy subjects (14 Female, 43 ± 12 yrs) were included. A comparison of ventilatory metrics during recovery between HF and controls is depicted in Figure 1. Peak VO2 was 1135 ± 419 mL/min (13.5 ± 3.8 mL/Kg/min) vs 2408 ± 787 mL/min (32.5 ± 9.0 mL/Kg/min); P Abstract Figure.

Objective The ventilation-to-carbon dioxide output (VE/VCO2) slope could predict morbidity and mortality after lung resection. The aim of the study was to identify whether VE/VCO2 slope obtained from cardiopulmonary exercise test (CPET) was an independent predictor of cardiopulmonary complications after anatomical pulmonary resection by video-assisted thoracic surgery (VATS). Methods We reviewed the files of all consecutive patients that underwent pulmonary anatomical resections by VATS between January 2010 and October 2020. The data were extracted from the registry of the Centre for Thoracic Surgery of Western Switzerland. Pneumonectomies were excluded from the study. We used a multivariable Cox regression to investigate the risk of cardiopulmonary complications associated with the VE/VCO2 slope and other possible confounders, including the Charlson Comorbidity Index (CCI), the CPET data and pulmonary functions. Results In total, 1392 patients (mean age: 66±11 years; ratio female: 47%) underwent anatomical resection by VATS. CPET was performed in 204 patients (15%). However, the VE/VCO2 slope data were available in 145 patients, which were included for the analysis. Patients underwent segmentectomies (N = 42) and lobectomies (N = 101) mainly for lung cancer (96%). The average percentage of the predicted VO2max was of 70±17%. Maximal effort during the CPET (respiratory coefficient ratio >1.1) was not reached in 30% of patients, without impact on the VE/VCO2 slope (39±6 vs 37±7, P = 0.21). Cardiopulmonary complications appeared in 32% of patients with no mortality at 90 days. In the multivariate analysis, VE/VCO2 slope >35 was correlated with cardiopulmonary complications (OR 3.5, 95% CI [1.3-9.3], P = 0.012). CCI, pulmonary functions, peak VO2 and the extension of the anatomical resection was not associated with cardiopulmonary complications. Conclusion VE/VCO2 slope above 35 predicts postoperative cardiopulmonary complications in anatomical resections by VATS. The VE/VCO2 slope is independent of the intensity of effort during the CPET. The impact of prehabilitation on the slope should be determined.

Carbon included in coke and coal was used as a reduction agent and fuel in blast furnace (BF) ironmaking processes, which released large quantities of carbon dioxide (CO2). Minimizing the carbon consumption and CO2 output has always the goal of ironmaking research. In this paper, the reduction reactions of iron oxides by carbon, the gasification reaction of carbon by CO2, and the coupling reactions were studied by thermodynamic functions, which were derived from isobaric specific heat capacity. The reaction enthalpy at 298 K could not represent the heat value at the other reaction temperature, so the certain temperature should be confirmed by Gibbs frees energy and gas partial pressure. Based on Hess’ law, the energy consumption of the ironmaking process by carbon was calculated in detail. The decrease in the reduction temperature of solid metal iron has been beneficial in reducing the sensible heat required. When the volume ratio of CO to CO2 in the top gas of the furnace was given as 1.1–1.5, the coupling parameters of carbon gasification were 1.06–1.28 for Fe2O3, 0.71–0.85 for Fe3O4, 0.35–0.43 for FeO, respectively. With the increase in the coupling parameters, the volume fraction of CO2 decreased, and energy consumption and CO2 output increased. The minimum energy consumption and CO2 output of liquid iron production were in the reduction reactions with only CO2 generated, which were 9.952 GJ/t and 1265.854 kg/t from Fe2O3, 9.761 GJ/t and 1226.799 kg/t from Fe3O4, 9.007 GJ/t and 1107.368 kg/t from FeO, respectively. Compared with the current energy consumption of 11.65 GJ/t hot metal (HM) and CO2 output of 1650 kg/tHM of BF, the energy consumption and CO2 of ironmaking by carbon could reach lower levels by decreasing the coupled gasification reactions, lowering the temperature needed to generate solid Fe and adjusting the iron oxides to improve the iron content in the raw material. This article provides a simplified calculation method to understand the limit of energy consumption and CO2 output of ironmaking by carbon reduction iron oxides.

The cardiopulmonary exercise test (CPET) provides an objective assessment of ventilatory limitation, related to the exercise minute ventilation (VE) coupled to carbon dioxide output (VCO2) (VE/VCO2); high values of VE/VCO2 slope define an exercise ventilatory inefficiency (EVin). In subjects recovered from hospitalised COVID-19, we explored the methodology of CPET in order to evaluate the presence of cardiopulmonary alterations. Our prospective study (RESPICOVID) has been proposed to evaluate pulmonary damage’s clinical impact in post-COVID subjects. In a subgroup of subjects (RESPICOVID2) without baseline confounders, we performed the CPET. According to the VE/VCO2 slope, subjects were divided into having EVin and exercise ventilatory efficiency (EVef). Data concerning general variables, hospitalisation, lung function, and gas-analysis were also collected. The RESPICOVID2 enrolled 28 subjects, of whom 8 (29%) had EVin. As compared to subjects with EVef, subjects with EVin showed a reduction in heart rate (HR) recovery. VE/VCO2 slope was inversely correlated with HR recovery; this correlation was confirmed in a subgroup of older, non-smoking male subjects, regardless of the presence of arterial hypertension. More than one-fourth of subjects recovered from hospitalised COVID-19 have EVin. The relationship between EVin and HR recovery may represent a novel hallmark of post-COVID cardiopulmonary alterations.

In smokers without manifest airway obstruction, early emphysema and endothelial dysfunction has been related to minute-ventilation/carbon dioxide output ratio (V′E/V′CO2). Thus, smokers with reduced lung carbon monoxide diffusion capacity (DLco) have a heightened V′E/V′CO2 ratio. We hypothesized that ventilatory inefficiency could contribute to the suspicion of impaired diffusive capacity in the absence of significant airway obstruction. Thus, 15 smokers with impaired DLco were compared to 15 smokers with normal DLco. Accuracy through sensibility and specificity for V′E/V′CO2 slope and nadir was compared with a new index for ventilatory efficiency (ηV′E,%), to uncover early diffusive changes in smokers without COPD.

Objective The Glittre-ADL test (GA-T) is a functional capacity test that stands out for encompassing multiple tasks similar to activities of daily living. As ventilatory efficiency is one of the variables valued in the prognosis of chronic heart failure (CHF), this study aimed to evaluate associations between functional capacity and ventilatory variables in patients with CHF during the GA-T. Results Eight patients with CHF and New York Heart Association (NYHA) functional classification II–III underwent the GA-T coupled with metabolic gas analysis to obtain data by means of telemetry. The median total GA-T time was 00:04:39 (00:03:29–00:05:53). Borg dyspnoea scale scores before and after the GA-T were 2 (0–9) and 3 (1–10), respectively (P = 0.011). The relationship between the regression slope relating minute ventilation to carbon dioxide output (VE/VCO2 slope) was correlated with the total GA-T time (rs = 0.714, P = 0.047) and Borg dyspnoea score (rs = 0.761, P = 0.028). The other ventilatory variables showed no significant correlations. Our results suggest that the total GA-T time can be applied to estimate the ventilatory efficiency of patients with CHF. Future studies may use the GA-T in conjunction with other functional capacity tests to guide the treatment plan and evaluate the prognosis.

Background Previous parameters such as peak VO2, VE/VCO2 slope and OUES have been described to be prognostic in heart failure (HF). The aim of this study was to identify further prognostic factors of cardiopulmonary exercise testing (CPET) in HF patients. Methods A retrospective analysis of HF patients who underwent CPET from January to November 2019 in a single centre was performed. PETCO2 gradient was defined by the difference between final PETCO2 and baseline PETCO2. HF events were defined as decompensated HF requiring hospital admission or IV diuretics, or decompensated HF resulting in death. Results A total of 64 HF patients were assessed by CPET, HF events occurred in 8 (12.5%) patients. Baseline characteristics are shown in table 1. Patients having HF events had a negative PETCO2 gradient while patients not having events showed a positive PETCO2 gradient (−1.5 [IQR −4.8, 2.3] vs 3 [IQR 1, 5] mmHg; p=0.004). A multivariate Cox proportional-hazards regression analysis revealed that PETCO2 gradient was an independent predictor of HF events (HR 0.74, 95% CI [0.61–0.89]; p=0.002). Kaplan-Meier curves showed a significantly higher incidence of HF events in patients having negative gradients, p=0.002 (figure 1). Conclusion PETCO2 gradient was demonstrated to be a prognostic parameter of CPET in HF patients in our study. Patients having negative gradients had worse outcomes by having more HF events. Time to first event, decompensated heart Funding Acknowledgement Type of funding source: None

Background Cardiopulmonary exercise testing (CPET) is recommended in the evaluation of selected patients with Heart Failure (HF). Notwithstanding, its prognostic significance has mainly been ascertained in those with left ventricular ejection fraction (LVEF) Methods We conducted a single-center retrospective study of consecutive patients with HF and LVEF Results Overall, 404 HF patients (mean age 57±11 years, 78.2% male, 55.4% ischemic HF) were included, of whom 321 (79.5%) had HFrEF and 83 (20.5%) HFmrEF. Compared to the former, those with HFmrEF had a significantly higher mean peak oxygen uptake (pVO2) (20.2±6.1 vs 16.1±5.0 mL/kg/min; p35 and EOV identified patients at higher risk for events (all p16.7 and >15.8 mL/kg/min more accurately identified patients at lower risk for the primary endpoint (NPV: 91.2 and 60.5% for HFmrEF and HFrEF, respectively; both p Conclusions CPET is a useful tool in HFmrEF. Both pVO2 and EOV independently predicted the primary endpoint in HFmrEF and HFrEF, contrasting with VE/VCO2, which remained predictive only in latter group. Our findings strengthen the prognostic role of CPET in HF with either reduced or mid-range LVEF. Funding Acknowledgement Type of funding source: None

High (⇑­) ventilation (VE)/carbon dioxide output (VCO2) ratio and low (⇓) end-tidal CO2 pressure (PETCO2) during exercise are expected in the presence of increased areas of ⇑ ­alveolar ventilation (VA) -capillary perfusion (Qc) relationship. Whether impaired Qc in isolation (i.e., pulmonary arterial hypertension (PAH)) furthers ⇑­VE/VCO2 and ⇓PETCO2 beyond expectations from diseases affecting both VA and Qc (i.e.,interstitial lung disease (ILD)) remains unclear. Resting lung function and responses to symptom-limited cycling incremental cardiopulmonary exercise test were analysed in PAH patients compared to chronic fibrosing ILD. 36 PAH patients (40.8±12.9yrs;8♂), 39 ILD (60.8±10.1yrs;24) and 16 controls (51.1±14.7yrs;6♂) were included. DLCO (62±15 vs 40±14%pred;p Despite more preserved DLCO and ⇓ hypoxic drive, pulmonary vascular dysfunction had a larger negative influence on exertional ventilatory and gas exchange efficiency than ILD. These findings show that increases in VE/VCO2 and decreases in PETCO2 point to potential pulmonary vascular dysfunction, a common chronic cardiopulmonary disease comorbidity.

Aim: CPET indicators are the part of risk stratification scale for patients mainly with IPAH, PAH-SS, corrected CHD. It is important to evaluate the impact of CPET on worsening or fatal events in risk stratification in patients with PAH-CHD and Eisenmenger syndrome (ES). Materials and Methods: 16 patients with PAH and simple unrepaired CHD and ES (PDA 33%, VSD 57%, ASD 10%) (35,5 [28,0;53,0] years) were underwent complex examination including CPET on cycle ergometry. Such factors that are part of the risk stratification scale as 6MWT distance (377,5 [330,0;450,0] meters), WHO FC (30%-II; 70%-III), right atrium area (19,0 [17,5;22,0] cm2), mRAP (5,5 [3,0;9,5] mm Hg), oxygen uptake (VO2), carbon dioxide output (VCO2), minute ventilation (VE) were measured. Results: The majority of patients had low exercise tolerance (3,4 [2,78;4,13] Меts). We revealed, that according to risk stratification scale without CPET indicators 13% of patients had the high risk of fatal events during 1 year, 50% - the intermediate risk and 37% - low risk. After including CPET indicators (VO2peak and VE/VCO2) we found, that an additional 6 pts (37%), who had been earlier in the intermediate risk, had a high risk of mortality during 1 year and an additional 4 (24%) of patients who had been earlier in the low risk, had an intermediate risk. The significant positive correlation between distance in 6MWT and VO2 peak (r=0,64, p Conclusion: VO2 peak and VE/VCO2 by CPET should apply as a useful part for risk stratification in patients with PAH-CHD and Eisenmenger syndrome for the choice of a treatment strategy.

Background and Aims It is well known that L-Carnitine is a cardioprotective agent, which balances cardiac energy metabolism, by promoting mitochondrial β-oxidation and facilitating transport of long chain fatty acids into the mitochondrial matrix. It has been shown that L-Carnitine level in plasma and tissue is lower in hemodialysis patients and they may lose the benefits of this substance. As far as our knowledge, the effect of L-Carnitine on cardiopulmonary function has not been evaluated by ergospirometry up to now. The aim of this randomized clinical trial was to assess the effects of L-carnitine supplementation on cardiopulmonary Function in hemodialysis patients through ergospirometry. Method This randomized clinical trial was conducted on 46 chronic hemodialysis patients. The patients were divided into two groups. In both groups ergospirometry parameters (VE Max, VO2-Max, VCO2 Max, AT, VE/VCO2 Slope) were recorded for a 3-month period. During this period, one group received L-Carnitine at doses of 2 gr/day orally and the other group received only placebo. After three months, all of the mentioned parameters were rechecked and statistical analysis performed by SPSS software. Results Only CRP was different between the two groups increasing in placebo group significantly after 3 months (P = 0.018). No significant difference was detected in Cardiopulmonary factors. In terms of ergospirometry factors, PET-CO2 was the only parameter significantly increased in the treatment group (P = 0.026). Conclusion The present results indicate that L-Carnitine can improve cardiopulmonary function among hemodialysis patients.

“Ventilatory efficiency” is widely used in cardiopulmonary exercise testing to make inferences regarding the normality (or otherwise) of the arterial CO2tension (PaCO2) and physiological dead-space fraction of the breath (VD/VT) responses to rapid-incremental (or ramp) exercise. It is quantified as: 1) the slope of the linear region of the relationship between ventilation (V′E) and pulmonary CO2output (V′CO2); and/or 2) the ventilatory equivalent for CO2at the lactate threshold (V′E/V′CO2) or its minimum value (V′E/V′CO2min), which occurs soon afterbut before respiratory compensation. Although these indices are normally numerically similar, they are not equally robust. That is, high values forV′E/V′CO2andV′E/V′CO2min provide a rigorous index of an elevatedVD/VTwhenPaCO2is known (or can be assumed) to be regulated. In contrast, a highV′E–V′CO2slope on its own does not, as account has also to be taken of the associated normally positive and smallV′Eintercept. Interpretation is complicated by factors such as: the extent to whichPaCO2is actually regulated during rapid-incremental exercise (as is the case for steady-state moderate exercise); and whetherV′E/V′CO2orV′E/V′CO2min provide accurate reflections of the true asymptotic value ofV′E/V′CO2, to which theV′E–V′CO2slope approximates at very high work rates.

Background: Ventilatory inefficiency is known to be a contributor to exercise intolerance in chronic obstructive pulmonary disease (COPD). The intercept of the minute ventilation (V̇E) vs. carbon dioxide output (V̇CO2) plot is a key ventilator inefficiency parameter. However, its relationships with lung hyperinflation (LH) and airflow limitation are not known. This study aimed to evaluate the correlations between the V̇E/V̇CO2 intercept and LH in COPD to determine its utility as an index of functional impairment.Methods: We conducted a retrospective analysis of data from 53 COPD patients and 14 healthy controls performed incremental cardiopulmonary exercise tests and resting pulmonary function. Ventilatory inefficiency was represented by parameters reflecting the V̇E/V̇CO2 nadir and slope (linear region), and intercept of the V̇E/V̇CO2 plot. Their correlations with measures of LH and airflow limitation were evaluated.Results: Compared to the control, the slope (30.58±3.62) and intercept (4.85±1.11) higher in COPDstages1-2, leading to a higher nadir (31.47±4.47) (pstages3-4 (7.16±1.41), the slope diminished with disease progression (from 30.58±3.62 in COPDstages1-2 to 28.36±4.58 in COPDstages3-4). Compared to the V̇E/V̇CO2 nadir and V̇E/V̇CO2 slope, the intercept was better correlated with peak V̇E/maximal voluntary ventilation (MVV) (r=0.489, p2/watt (r=0.354, p=0.003). The intercept was also significantly correlated with RV/TLC (r=0.588, pr=-0.574, pT/TLC (r=-0.585, p1) % predicted (r=-0.606, p1/forced vital capacity (FVC) (r=-0.629, pConclusion: V̇E/V̇CO2intercept was consistently better correlated with worsening static and dynamic lung hyperinflation and airflow limitation in COPD. V̇E/V̇CO2 intercept emerged as a useful index of ventilatory inefficiency across the severity spectrum of COPD patients.

Background valsartan and sacubitril combination (angiotensin receptor-neprilysin inhibitor, ARNI) was superior, in randomized trials, to lone ACE inhibitors in terms of reduction of cardiovascular mortality rate and hospitalization for acute heart (HF) in patients with HF with reduced ejection fraction (HFrEF). Purpose: the main goal of our study was to assess the effects of ARNI on left atrial (LA) and left (LV) and right ventricular (RV) function, evaluated by standard and speckle tracking echocardiography (STE), and on patients’ functional capacity by cardiopulmonary exercise testing (CPET), in patients with HFrEF. Methods: we prospectively enrolled 16 patients with a LV EF ≤35% and >18 years old, in two different centers with high expertise in HF management. Exclusion criteria included: symptomatic hypotension, stage IV renal failure (eGFR < 30 ml/min/1.73 m2), ACE-inhibitor (ACEi) intolerance or previous angioedema, poor acoustic window, refuse to participate to the study. At enrollment (T0), all patients were in therapy with ACEi or sartans (ARBs) and underwent physical examination, ECG, blood test (including NT-proBNP), standard echo, STE and CPET. We shifted therapy from ACEi/ARBs according to HF guidelines and we repeated all tests after 6 months. Results: population had an average age of 63 ± 9 years, 94% was males. Etiology was ischemic in one third of the subjects. At 6 months follow up, NT-proBNP was significantly lower (512.2 ± 518.5 vs 431.2 ± 330.1 ng/l, p 0,001) together with reduced LV filling pressure evaluated by E/A ratio and E/e’ ratio (11.2 ± 8.6 vs 8.8 ± 4.8, p 0.01). LV EF improved from 31.7 ± 3.4% to 36.2 ± 7.2% (p 0.01) and LV dimensions decreased. LV global longitudinal strain (GLS) did not change significantly while free wall RV GLS increased from – 20.4 ± 6.3% to – 24.6 ± 9%, p 0.001, as peak atrial longitudinal strain (PALS) did (16.1 ± 2.6% vs 27.6 ± 4.1%, p 0.001). Between CPET indexes, only VE/VCO2 slope improved but only with borderline statistical significance (32.7 ± 5.3 vs 29.7 ± 6.8, p 0.05, Fig. 1). Conclusions: this preliminary study evaluated for the first time the effects of ARNI on echocardiographic and CPET parameters at the same time. Our results could explain the favorable clinical benefits of ARNI therapy in HFrEF: improved biventricular function, lower LV filling pressure and a more efficient ventilatory response during effort. Abstract P215 Figure. Fig.1

Background Right ventricle to pulmonary circulation (RV-PC) coupling plays a pivotal role during the physical effort. The RV-PC uncoupling can be easily identified by the TAPSE/SPAP ratio, a prognostic marker based on RV longitudinal function and its afterload (SPAP).We sought to explore the relationship between the functional capacity (peak VO2 and VE/VCO2) and the RV-PC coupling, using both a standard and 3D-based echocardiographic assessment of RV. Methods eighty-seven patients (age 72 ± 10 years; LV EF 53 ± 15%) underwent rest echocardiography with 3D RV assessment and cardiopulmonary exercise test. RV EF was measured using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software. This provided longitudinal (EFlong) and circumferential (EFcirc) components of EF. RV-PC coupling was assessed with the TAPSE/SPAP ratio and with similar parameters obtained by using 3D components of RV systolic function over SPAP (EF/SPAP, EFlong/SPAP and EFcirc/SPAP ratio). All variables were correlated with peakVO2 and VE/VCO2. Results Correlations between peakVO2 and TAPSE (0.409, p = 0.006), SPAP (-0.597, p Conclusions RV-PC coupling is associated with both peak VO2 and VE/VCO2. The use of 3D-derived markers of RV-PC coupling showed a better correlation with the peak VO2, while there were no differences for VE/VCO2. The circumferential component of RV systolic function seems to emerge as a dominant determinant of RV-PC coupling, as well as of functional capacity.

INTRODUCTION In light of the recent increase in terrorist events around the globe, it is surprising that the metabolic demand of counter-terror fighting tasks had not yet been published in the scientific literature. The purpose of this study, therefore, was to examine the metabolic demand and the contribution of the three energy systems to a typical simulated counter-terror combat scenario. MATERIALS AND METHODS Oxygen uptake and carbon dioxide output (VO2, VCO2), heart rate, ventilatory responses, and blood lactate concentration were measured in 12 randomly selected elite Special Forces police fighters (mean age 33.3 ± 3.6 years). The fighting task involved ascending flights of stairs, climbing a ladder, shooting on hiding terrorists, performing a search and rescue, relocating a wounded colleague, and then descending and exiting from a seven-floor building. RESULTS The fighting scenario lasted an average of 4:56 ± 0:22 min. Measured oxygen uptake averaged 31.1 ± 2.0 ml kg min-1 (57.7% of VO2max) with an average peak of 37.7 ± 8.1 ml kg min-1 (75.5% of VO2max). Average and peak heart rates were 160.4 ± 12.2 beats min-1 (85% of the HRmax) and 175.5 ± 10.5 beats min-1 (94% of HRmax), respectively. The energy cost of the fighting scenario averaged 74.3 ± 9.9 Kcal, with 75.5% of the energy generated by aerobic pathways, 14.1% from anaerobic lactacid (glycolytic) and 10.4% from anaerobic a-lactacid (phosphogenic) energy sources. CONCLUSIONS This study provided novel information related to the physiological demands and the metabolic fuel supplies during a typical counter-terror-fighting task of elite Special Forces. Such information is instrumental in planning and conducting adequate training programs and nutrition support for counter-terror fighting units.

Background Energy cost of transport per unit distance (CoT) against speed shows U-shaped fashion in walking and linear fashion in running, indicating that there exists a specific walking speed minimizing the CoT, being defined as economical speed (ES). Another specific gait speed is the intersection speed between both fashions, being called energetically optimal transition speed (EOTS). We measured the ES, EOTS, and muscle activities during walking and running at the EOTS under hyperoxia (40% fraction of inspired oxygen) on the level and uphill gradients (+ 5%). Methods Oxygen consumption \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left(\dot{V}{\mathrm{O}}_2\right) $$\end{document}V˙O2 and carbon dioxide output \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \left(\dot{V}{\mathrm{CO}}_2\right) $$\end{document}V˙CO2 were measured to calculate the CoT values at eight walking speeds (2.4–7.3 km h−1) and four running speeds (7.3–9.4 km h− 1) in 17 young males. Electromyography was recorded from gastrocnemius medialis, gastrocnemius lateralis (GL), and tibialis anterior (TA) to evaluate muscle activities. Mean power frequency (MPF) was obtained to compare motor unit recruitment patterns between walking and running. Results \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{V}{\mathrm{O}}_2 $$\end{document}V˙O2, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{V}{\mathrm{CO}}_2 $$\end{document}V˙CO2, and CoT values were lower under hyperoxia than normoxia at faster walking speeds and any running speeds. A faster ES on the uphill gradient and slower EOTS on both gradients were observed under hyperoxia than normoxia. GL and TA activities became lower when switching from walking to running at the EOTS under both FiO2 conditions on both gradients, so did the MPF in the TA. Conclusions ES and EOTS were influenced by reduced metabolic demands induced by hyperoxia. GL and TA activities in association with a lower shift of motor unit recruitment patterns in the TA would be related to the gait selection when walking or running at the EOTS. Trial registration UMIN000017690 (R000020501). Registered May 26, 2015, before the first trial. Electronic supplementary material The online version of this article (10.1186/s40101-018-0177-7) contains supplementary material, which is available to authorized users.

Cardiopulmonary exercise testing (CPET) is a frequently used tool in the differential diagnosis of dyspnoea. Ventilatory inefficiency, defined as high minute ventilation (V′E) relative to carbon dioxide output (V′CO2), is a hallmark characteristic of pulmonary vascular diseases, which contributes to exercise intolerance and disability in these patients. The mechanisms of ventilatory inefficiency are multiple and include high physiologic dead space, abnormal chemosensitivity and an altered carbon dioxide (CO2) set-point. A normalV′E/V′CO2makes a pulmonary vascular disease such as pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) unlikely. The finding of highV′E/V′CO2without an alternative explanation should prompt further diagnostic testing to exclude PAH or CTEPH, particularly in patients with risk factors, such as prior venous thromboembolism, systemic sclerosis or a family history of PAH. In patients with established PAH or CTEPH, theV′E/V′CO2may improve with interventions and is a prognostic marker. However, further studies are needed to clarify the added value of assessing ventilatory inefficiency in the longitudinal follow-up of patients.

Introduction The beneficial impact of an 8-month competitive season on the ventilatory profile response to exercise in soccer players has never been evaluated. Material and methods Ventilatory profile (evaluated by determining individual tidal volume [VT] relative to minute ventilation [VE] inflection points during exercise) and metabolic responses to incremental exercise were evaluated in 2 professional soccer teams before and after an 8-month competitive season. Results No differences between teams in anthropometric characteristics or in resting cardiopulmonary variables, included oxygen uptake (VO2) and heart rate (HR), before and during the competitive season were found. At iso-speed, there were overall improvements in carbon dioxide output (VCO2), VE/VO2, VE/VCO2, VE and respiratory frequency (fR) during the season. The VT/VE inflection points 1 and 2 occurred with greater exercise time, HR, VO2, VCO2, VE and VT during the competitive season. Conclusions Despite very high baseline performance and a negligible improvement in VO2, an 8-month competitive season improved ventilatory profile response to exercise in elite athletes.

Purpose The aim of the present study was to test the correlation of the exercise lung ultrasound (LUS) and B-lines count with clinical, laboratory and echocardiographic parameters among patients with preserved left ventricle ejection fraction and without signs of congestion reffered for cardiopulmonary exercise test (CPET) for exertional dyspnea. Methods The study population consisted of 39 patients (age 63.0±9.3 years; 62% females) with preserved ejection fraction (≥50%) and without signs of congestion reffered for exercise testing. Pulmonary disease and coronary artery disease was ruled out. CPET, rest and stress echocardiography and B-lines count assessed by 8 zone LUS were performed. Results Exercise B-lines count was significantly higher than rest B-lines count (3.1±0.5 vs. 1.1±0.2; p Characteristics of study population Rest and peak exercise B-lines count Conclusion We observed weak but significant correlation between exercise B-lines count and left atrium diameter. However we didn't observe significant difference between HFpEF patients and rest of study population in B-lines count. Limitation of our observation is small study population.

Aim: To evaluate the impact of CPET on fatal events risk stratification in patients with pulmonary arterial hypertension, associated with congenital heart disease (PAH-CHD). Material and Methods: 20 patients with PAH associated with simple unrepaired CHD (PDA 40%, VSD 50%, ASD 10%)(mean age 38,45±9,08 years) were underwent complex examination including CPET on cycle ergometry. Such factors as 6MWT distance (459,3±69,9 meters), WHO FC (65%-I-II; 35%-III-IV), load capacity (46±12,8 Vt), right atrium area (20,2±5,78 cm2), mRAP (5,4±2,4 mm Hg), SVO2(69,1±6,34%), CI (2,67±0,5), oxygen uptake (VO2), carbon dioxide output (VCO2), minute ventilation (VE) were measured. Patients with IPAH (n=20) were the control group. Results: Two groups were comparable in all basic characteristics. We revealed, that the majority of pts (55%) had the high risk of fatal events during 1 year, and 30% had the intermediate risk. After the CPET we found, that an additional 10 pts, who had been earlier in the intermediate risk, had a high risk of mortality during 1 year. 10% of patients were belonged to the low risk, that was also confirmed by CPET data. The significant positive correlation between distance in 6MWT and VO2peak (r=0,67, p Conclusion: For the assessment of achieving therapy goals CPET is one of the reliable markers to reflect the PAH progression. CPET is useful in risk stratification in patients with PAH-CHD.

Sofia E. Kjellman grapples with her carbon dioxide output resulting from her work as a scientist. Sofia E. Kjellman grapples with her carbon dioxide output resulting from her work as a scientist.

The use of automated gas exchange analysis systems in exercise studies is common throughout the industrialized world and are frequently used in sports medicine laboratories for the measurement of maximal oxygen uptake (VO2max), as an integrative parameter that allows the physical condition to be assessed, in spite of its limitations. Actually, the fundamental principles behind the measurement of respiratory gas exchange (RGE) have not changed for a century. It was used a manual Douglas bag method together with separate chemical analyses. The need for faster and more efficient techniques, has conditioned the traditional procedures and determined the emergence of automated systems. However, the validity and reliability of all these different systems is not well known. The common features associates with these systems, also have disadvantages that must be evaluated at the time of the acquisition of an automated equipment: (1) regular quality control checks, which entails other added economic costs, (2) the validity and reliability of the results, which it is necessary to verify, and (3) the user does not know the equations that determine the values of oxygen consumption and carbon dioxide production. This work aims to clarify the disadvantages of these automated systems. At maximum intensities, the variation of VO2max or VO2peak can be very significant in athletes and even more relevant in sick people undergoing a training program. Therefore, considerable care is needed when comparing RGE data with automated systems. New and noteworthy Actually, stress tests are more conveniently performed with automated systems. It is necessary to examine the validity and reliability of automated respiratory gas exchange systems. The algorithms incorporated in the software, apart from being a "mystery," show differences with respect to the data provided.