Oxygen Uptake Efficiency Plateau Research Articles

Oxygen uptake efficiency plateau is unaffected by fitness level - the NOODLE study

BackgroundEndurance athletes (EA) are an emerging population of focus for cardiovascular health. The oxygen uptake efficiency plateau (OUEP) is the levelling-off period of ratio between oxygen uptake (VO2) and ventilation (VE). In the cohort of EA, we externally validated prediction models for OUEP and derived with internal validation a new equation.Methods140 EA underwent a medical assessment and maximal cycling cardiopulmonary exercise test. Participants were 55% male (N = 77, age = 21.4 ± 4.8 years, BMI = 22.6 ± 1.7 kg·m− 2, peak VO2 = 4.40 ± 0.64 L·min− 1) and 45% female (N = 63, age = 23.4 ± 4.3 years, BMI = 22.1 ± 1.6 kg·m− 2, peak VO2 = 3.21 ± 0.48 L·min− 1). OUEP was defined as the highest 90-second continuous value of the ratio between VO2 and VE. We used the multivariable stepwise linear regression to develop a new prediction equation for OUEP.ResultsOUEP was 44.2 ± 4.2 mL·L− 1 and 41.0 ± 4.8 mL·L− 1 for males and females, respectively. In external validation, OUEP was comparable to directly measured and did not differ significantly. The prediction error for males was − 0.42 mL·L− 1 (0.94%, p = 0.39), and for females was + 0.33 mL·L− 1 (0.81%, p = 0.59). The developed new prediction equation was: 61.37–0.12·height (in cm) + 5.08 (for males). The developed model outperformed the previous. However, the equation explained up to 12.9% of the variance (R = 0.377, R2 = 0.129, RMSE = 4.39 mL·L− 1).ConclusionOUEP is a stable and transferable cardiorespiratory index. OUEP is minimally affected by fitness level and demographic factors. The predicted OUEP provided promising but limited accuracy among EA. The derived new model is tailored for EA. OUEP could be used to stratify the cardiorespiratory response to exercise and guide training.

Improved Oxygen Uptake Efficiency Parameters Are Not Correlated with VO2peak or Running Economy and Are Not Affected by Omega-3 Fatty Acid Supplementation in Endurance Runners.

Peak oxygen uptake (VO2peak) is one of the most reliable parameters of exercise capacity; however, maximum effort is required to achieve this. Therefore, alternative, and repeatable submaximal parameters, such as running economy (RE), are needed. Thus, we evaluated the suitability of oxygen uptake efficiency (OUE), oxygen uptake efficiency plateau (OUEP) and oxygen uptake efficiency at the ventilatory anaerobic threshold (OUE@VAT) as alternatives for VO2peak and RE. Moreover, we evaluated how these parameters are affected by endurance training and supplementation with omega-3 fatty acids. A total of 26 amateur male runners completed a 12-week endurance program combined with omega-3 fatty acid supplementation or medium-chain triglycerides as a placebo. Before and after the intervention, the participants were subjected to a treadmill test to determine VO2peak, RE, OUE, OUEP and OUE@VAT. Blood was collected at the same timepoints to determine eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in erythrocytes. OUE correlated moderately or weakly with VO2peak (R2 = 0.338, p = 0.002) and (R2 = 0.226, p = 0.014) before and after the intervention, respectively. There was a weak or no correlation between OUEP, OUE@VAT, VO2peak and RE despite steeper OUE, increased OUEP and OUE@VAT values in all participants. OUE parameters cannot be treated as alternative parameters for VO2peak or RE and did not show changes following supplementation with omega-3 fatty acids in male amateur endurance runners.

A clinical research report on the pathophysiological characteristics of exercise in patients with mitral regurgitation

Objective: Cardiopulmonary exercise testing (CPET) was used to investigate the exercise pathophysiology of mitral regurgitation. Methods: 26 patients with moderate and severe mitral regurgitation who completed standardized extreme exercise CPET under strict quality control after signing informed consent since 2016, and 11 normal subjects in the same period as the control group. The core indexes of CPET were analyzed and calculated according to the standard method and compared with normal subjects for intergroup statistical independent sample t-test. At the same time, the patients with heart failure and exercise oscillation breathing (OB) were divided into two subgroups: 11 cases without heart failure, 15 cases with heart failure, 8 cases with non-OB and 18 cases with OB, and their similarities and differences were compared between each subgroup. Results: The core indexes of CPET, such as peak oxygen uptake (85.60 ±9.06)%pred and anaerobic threshold (AT, (87.59 ±15.38)%pred) were normal. The peak oxygen uptake of CPET in patients with mitral regurgitation was (48.15 ±12.11)%pred, peak oxygen pulse was (66.57 ±12.20)%pred, AT was (56.75 ±11.50)%pred, oxygen uptake efficiency plateau was (88.24 ±16.42)%pred , lowest value of carbon dioxide ventilatory efficiency was (125.89 ±27.05)%pred and slope of carbon dioxide ventilatory efficiency was (128.31 ±31.68)%pred. Among them, only oxygen uptake efficiency plateau (OUEP) was normal and low, and the other indexes were significantly abnormal. There were significant differences between the patients and the control group (P<0.01). There was no significant difference between the non-OB group and the OB group, but there was significant difference between the non-OB group and the control group (P<0.05). There was no significant difference between the non-heart failure group and the heart failure group, but there was significant difference between the non-heart failure group and the control group. Conclusion: All the core indexes of cardiopulmonary exercise are significantly abnormal in patients with mitral regurgitation who are significantly lower than those in normal subjects except for the low effectiveness of oxygen ventilation. And with or without heart failure and OB did not affect the cardiopulmonary function.

Cardiopulmonary exercise testing was used to evaluate objectively and quantitatively the holistic function in patients after neoadjuvant chemotherapy

Objective: Cardiopulmonary exercise testing(CPET)was used to evaluate objectively and quantitatively the holistic function in patients accepted preoperative chemotherapy. Methods: This study investigated reliable objective and quantitative assessment methods of symptom limited maximal incremental CPET before and after chemotherapy in patients with 6 esophageal cancer. We re-analyzed the changes in cardiopulmonary, metabolism, and other functions physiologic parameters of CPET. Results: After patients accepted preoperative chemotherapy,Peak oxygen consumption (Peak VO2)(P<0.05), anaerobic threshold (AT) and peak oxygen pulse (Peak O2 paulse), oxygen uptake efficiency plateau (OUEP)were decreased (P<0.01). The lowest of ventilatory equivalent for carbon dioxide and slope of ventilatory equivalent for carbon dioxide were increased (P<0.05). For individual of all patients, except one patient's Peak VO2 and OUEP slightly increased,all of the above indicators were reduced in the remaining patients. The lowest of ventilatory equivalent for carbon dioxide and slope of ventilatory equivalent for carbon dioxide increased in all the patients,except one patient's slope of ventilatory equivalent for carbon dioxide decreased slightly. The heart rate of 6 patients showed an upward trend in each state, but there was no statistical difference. Three of the 6 patients had blood pressure measurement, and the other 3 patients had a significant decrease in diastolic blood pressure (P<0.05) except at extreme state.The patients had lower oxygen uptake at AT(P<0. 01) and extreme state (P<0. 05) than that before chemotherapy. The oxygen uptake efficiency in a warm-up state(P<0. 01),and an AT state(P<0. 05)after chemotherapy were lower than those before chemotherapy. The ventilator equivalent for carbon dioxide after chemotherapy was in the each states presented an upward trend, but only ventilator equivalent for carbon dioxide after in the warm-up state (P<0.05) and AT(P<0.01) had statistical significance. oxygen pulse in all four states showed a decreasing trend, and only at AT (P<0.05) showed a significant decrease.After chemotherapy,the PETCO2 in a warm-up state after chemotherapy was lower than that before chemotherapy(P<0. 05); the PETO2 in a quiescent state,a warm - up state,and an extreme state after chemotherapy were higher than those before chemotherapy;but there was nosignificant difference. Conclusion: The holistic functional capacity of patients with esophageal significantly decreased after 136 days chemotherapy. The circulatory functionalandentilator functional parameters significantly decreased after chemotherapy.

Cardiopulmonary exercise testing (CPET)to evaluate the efficacy after intensive control of personalized precise exercise training for cardiovascular and cerebrovascular chronic diseases

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.

Maximal oxygen consumption and oxygen uptake efficiency in adolescent males

Background/objectiveMeasures of oxygen uptake efficiency (OUE) have been used to evaluate cardiorespiratory fitness (CRF) in adolescents unable to perform maximal exercise. The oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP) have been proposed as surrogates for maximal oxygen consumption (V̇O2max). We assessed the validity of the OUES and OUEP as predictors of V̇O2max in healthy male adolescents. MethodsSixty-three healthy male adolescents aged 15.40 ± 0.34 years underwent an incremental treadmill test to determine V̇O2max, OUES and OUEP. OUE throughout the test was assessed by dividing each V̇O2 value by the corresponding minute ventilation (V̇E) value. OUEP was determined as the 90 s average highest consecutive values for OUE. OUES was determined using data up to the ventilatory threshold (VT) by calculating the slope of the linear relation between V̇O2 and the logarithm of V̇E. ResultsLimits of agreement for V̇O2max predicted by OUES (±13.3 mL kg−1.min−1) and OUEP (±16.7 mL kg−1.min−1) relative to V̇O2max were wide and a magnitude bias was found for OUES and OUEP as predictors of V̇O2max (p < 0.001). ConclusionThe OUES and OUEP do not accurately predict V̇O2max in male adolescents and should not replace V̇O2max when assessing CRF in this population.

The Personalized Precise Exercise Training Holistic Integrative Protocol (PPET‐HIP) for Patient with Myocardial Incompetence and Catecholamine‐Sensitive Ventricular Arrhythmia after her Sudden Cardiac Arrest

INTRODUCTIONSThe patient was a 23yrs female nurse in Fuwai‐hospital. After 2d overtime work, she had suddenly cardiac arrested followed by successful CPR and 5hr unconsciousness. Afterward she was diagnosed as catecholamine‐sensitive ventricular tachycardia, myocardial insufficiency and etc; and some physicians suggested installing of cardiac pacemaker with ICD. However, based on HIPM, we believe her main problem was the mismatching of supply‐demand and poor integration among systems, and Personalized Precise exercise Training Holistic Integrative Protocol (PPET‐HIP)can reverse those. We suggested give us ~100d PPET‐HIP and then decide for pacemaker‐ICD.METHODSAfter performing symptom limited maximum cardiopulmonary exercise testing (CPET) for objectively quantitative evaluation, we generated her PPET‐HIPΔ50% Power for intensity titration. According to results of continuous beat‐by‐beat blood pressure and continuous blood glucose monitoring during 30min Δ50% Power intensity titration we did select qid, 6d/w intensive management.RESULTSAfter 1m of intensive management, her continuation duration of PPET‐HIP was increased from 1–2min to 6–7min. The total exercise duration was increased from 17 to 24min, and resting was decreased from 8–10 to 3–4 times/30min. In 1st CPET, ventricular premature (PVC) began from loading intensity over 75w/min until peak loading127.5W/min , and total PVC was 119beat/130s.After three‐month PPET‐HIP,CPET showed PVC began from loading intensity over 100w/min until peak loading 162.5W/min , and total PVC was 68beat/170s. Comparing with the 1st one, three‐month CPET’s key parameters of peakVO2, AT, peak loading, peak CO and oxygen uptake efficiency plateau (OUEP) were increased by 20.1%, 15.2%, 21.5% and 22.5%, 21.7% and 5.7% respectively, only VE/VCO2 was decreased by 5.4%; all indicated improvement of functional status. The she has been believed that she couldn’t be nursing work again. However, after leaving Fuwai, she has become a clinical nurse again and working in cardiac rehabilitation, which is very meaningful for her.CONCLUSION Under the guidance of HIPM, we could safely and effectively manage patients by PPET‐HIP. Increased functional capacity parameters in CPET by 5–23%. Increased threshold of PVC and decreased rate of PVC during CPET. Decreased number of PVC and decreased rate of PVC in 30min training of PPET‐HIP.Support or Funding InformationNational Natural Science Foundation of China (81470204);Fuwai Hospital, National Cardiovascular Institute of Chinese Academy of Medical Sciences (2012‐YJR02);Research on Clinical Characteristics of the Capital (Z141107002514084);Research and Outcome Promotion of Clinical Characteristics in the Capital (Project No. Z161100000516127)

Characteristics of exercise capacity in female systemic lupus erythematosus associated pulmonary arterial hypertension patients

BackgroundTo study the oxygen uptake efficiency and determine usefulness of submaximal parameters of oxygen uptake in systemic lupus erythematosus associated pulmonary arterial hypertension (SLE PAH) on performing a cardiopulmonary exercise test (CPET).MethodsCPET was performed in 21 SLE PAH patients, equal number of idiopathic pulmonary arterial hypertension (IPAH) patients and controls. Peak VO2, anaerobic threshold (AT), oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP) and other CPET parameters were examined. All subjects had pulmonary function test (PFT) at rest, which included FEV1, FVC, FEV1/FVC, DLCO measurements. Right heart catheterization (RHC) was also done in SLE PAH and IPAH patients. CPET parameters were compared with RHC parameters to determine potential correlations.ResultsPeak VO2, PETCO2 and peak O2 pulse were lower in SLE PAH than IPAH and controls with OUE being lower during all stages of exercise in SLE PAH. DLCO and FVC values were significantly lower in SLE PAH (p < 0.05). Peak O2 pulse and VO2@AT in SLE PAH and IPAH was low (p < 0.05) and significant difference between SLE PAH and IPAH was seen (p < 0.05). PVR correlated with the lowest VE/VCO2, O2 pulse, peak PETCO2 and OUE in SLE PAH patients (all p < 0.05).ConclusionsSLE PAH patients have cardiopulmonary exercise limitation with reduced oxygen uptake efficiency. VO2@ at AT, peak O2 pulse and O2 pulse at AT were significantly reduced (p < 0.05). Key CPET parameters correlated with elevated pulmonary vascular resistance (PVR). Submaximal parameters of oxygen uptake are equally useful in SLE PAH.

Cardiopulmonary exercise testing improves diagnostic specificity in patients with echocardiography-suspected pulmonary hypertension.

Doppler echocardiography is usually the first diagnostic investigation for patients suspected with pulmonary hypertension (PH), but it is often inaccurate when used alone, especially in mild PH. Cardiopulmonary exercise testing (CPET) may serve as a complementary tool to improve diagnostic accuracy in echocardiography-suspected "PH possible" patients. Eighty-eight consecutive patients with suspected PH (referred to as "PH possible" hereafter) based on echocardiography were included in the study. CPET was assessed subsequently and PH was confirmed by right-heart catheterization in all subjects. We analyzed CPET data from patients and derived a CPET prediction rule to hemodynamically differentiate PH. Eighty-eight patients (27 patients with confirmed PH, and PH ruled out in 61 patients) were included in the study. Compared with non-PH patients, the PH subjects had lower peak oxygen uptake (VO2 ), aerobic capacity (AT), peak partial pressure of end-tidal CO2 (PET CO2 ), oxygen uptake efficiency plateau (OUEP), and oxygen uptake efficiency slope (OUES), along with higher minute ventilation (VE)/carbon dioxide output (VCO2 ) slope and lowest VE/VCO2 (P < 0.001). VE/VCO2 slope and AT were independent predictors of PH derived from multivariate logistic regression adjusted for age and body mass index. A score combining VE/VCO2 slope and AT reached a high area under the curve value of 0.98. A score ≥0.5 had 95% specificity and 92.6% sensitivity for diagnosis of PH. A score combining VE/VCO2 slope and AT provides high specificity in screening out PH from a pool of echocardiography-suspected PH patients.

Assessing utility of exercise test in determining exercise prescription in adolescent and adult patients with repaired tetralogy of fallot.

Parameters from cardiopulmonary exercise test (CPET) are useful prognostic factors for patients with repaired tetralogy of fallot (TOF). Its application in exercise prescription remains unclear. This study sought to define its role. We made current exercise recommendations in repaired TOF patients according to European Society of Cardiology (ESC) guideline, which were based on ventricular function, pressure/volume load, pulmonary artery pressure, hypoxemia and arrhythmic burden both at rest and during exercise. CPET parameters (peak oxygen consumption, oxygen uptake efficiency plateau, and E/CO2 slope), along with cardiothoracic ratio, ventricular arrhythmia, QRS duration and NYHA functional status, were used to calculate "score to exercise". 112 repaired TOF adolescent and adult aged 32.6±10.8 (14.05- to 56.99-year-old, median 30.1) years received exercise recommendations by ESC guideline, which suggested high, moderate and low intensity sports for 45 (40.2%), 45 (40.2%), and 22 (19.6%) patients, respectively. The optimal cut-off values were 67 and 77% for peak VO2, 86 and 100% for OUEP, 22 and 28 for E/CO2 slope to correlate to the exercise intensity recommendation. But, individual CPET parameter had low consistency (41-46%) in making decisions of exercise intensity compared to ESC recommendations. Using the "score to exercise", the consistency rate could be increased to 74.1%. With "score to exercise" recommended exercise intensity, follow-up result revealed no adverse event related to sports. Individual CPET parameter did not correlate well to the exercise recommendation from ESC. We proposed a scoring system, "score to exercise", which incorporates three CPET parameters with cardiothoracic ratio, ventricular arrhythmia, QRS duration and NYHA functional status. Score to exercise is easy to be assessed and provides useful information for exercise recommendation in patients with repaired TOF.

Assessing Late Cardiopulmonary Function in Patients with Repaired Tetralogy of Fallot Using Exercise Cardiopulmonary Function Test and Cardiac Magnetic Resonance.

Patients with repaired tetralogy of Fallot (TOF) usually experience progressive right ventricle (RV) dysfunction due to pulmonary regurgitation (PR). This could further worsen the cardiopulmonary function. This study aimed to compare the changes in patient exercise cardiopulmonary test and cardiac magnetic resonance imaging, and consider the implication of these changes. Our study examined repaired TOF patients who underwent cardiopulmonary exercise test (CPET) to obtain maximal (peak oxygen consumption, peak VO2) and submaximal parameters (oxygen uptake efficiency plateau, oxygen uptake efficiency plateau (OUEP), and ratio of minute ventilation to carbon dioxide production, VE/VCO2 slope). Additionally, the hemodynamic status was assessed by using cardiac magnetic resonance. Criteria for exclusion included TOF patients with pulmonary atresia, atrioventricular septal defect, or absence of pulmonary valve syndrome. We enrolled 158 patients whose mean age at repair was 7.8 ± 9.1 years (range 0.1-49.2 years) and the mean patient age at CPET was 29.5 ± 12.2 years (range 7.0-57.0 years). Severe PR (PR fraction ≥ 40%) in 53 patients, moderate in 55, and mild (PR fraction < 20%) in 50 patients were noted. The mean RV end-diastolic volume index (RVEDVi) was 113 ± 35 ml/m(2), with 7 patients observed to have a RVEDVi > 163 ml/m(2). The mean left ventricular ejection fraction (LVEF) was 63 ± 8%, left ventricular end-diastolic volume index (LVEDVi) was 65 ± 12 ml/m(2), and LVESVi was 25 ± 14 ml/m(2). CPET revealed significantly decreased peak VO2 (68.5 ± 14.4% of predicted), and fair OUEP (90.3 ± 14.1% of predicted) and VE/VCO2 slope (27.1 ± 5.3). PR fraction and age at repair were negatively correlated with maximal and submaximal exercise indicators (peak VO2 and OUEP). Left ventricular (LV) function and size were positively correlated with peak VO2 and OUEP. The results of CPET showed that patients with repaired TOF had a low maximal exercise capacity (peak VO2), but a fair submaximal exercise capacity (OUEP and VE/VCO2 slope), suggesting limited exercise capability in high intensity circumstances. PR, LV function and age at total repair were the most important determinants of CPET performance. Cardiac magnetic resonance; Cardiopulmonary exercise function; Pulmonary regurgitation; Surgical age; Tetralogy of Fallot.

Oxygen Uptake Efficiency Slope, an Objective Submaximal Parameter in Evaluating Exercise Capacity in Pulmonary Thromboembolism

ObjectiveThe objective of this article was to study the oxygen uptake efficiency, an index of cardiopulmonary functional reserve that can be based upon a submaximal exercise effort, in pulmonary thromboembolism (PE) by performing the cardiopulmonary exercise test. Materials and MethodsThe cardiopulmonary exercise test with simultaneous respiratory gas measurement was performed in 50 patients with PE and in 50 healthy individuals. All subjects also underwent the pulmonary function test. Peak oxygen uptake (peak VO2), anaerobic threshold (AT), oxygen uptake efficiency slope (OUES), oxygen uptake efficiency plateau (OUEP) and oxygen uptake efficiency at anaerobic threshold (OUE@AT), were determined. Results(1) Compared with the controls, the patients with PE had lower peak VO2, AT, OUES, OUEP and OUE@AT (P < 0.001). (2) In patients with PE, oxygen uptake efficiency (OUE = VO2/VE) at warming up, AT and peak exercise but not rest, were indicated statistically lower than the controls. The OUE in normal subjects increased as unloaded exercise began, and then increased further to OUEP just before the AT. Thereafter, the OUE decreased gradually until peak exercise. In contrast, the rate of changes of the OUE in patients with PE was relatively mild during exercise. (3) Of all the submaximal parameters, OUES correlated best with peak VO2 (r = 0.712, P < 0.001). ConclusionsThe oxygen uptake efficiency of patients with PE was lower than the controls during exercise. The OUE is an objective measure of cardiopulmonary reserve that does not require a maximal exercise effort. Therefore, OUES could be helpful to assess exercise performance in patients with PE who are unable to perform a maximal exercise test in early recovery stage.

Response profiles of oxygen uptake efficiency during exercise in healthy children.

Oxygen uptake efficiency (OUE), the relation between oxygen uptake (VO2) and minute ventilation (VE), differs between healthy children and children with heart disease. This study aimed to investigate the normal response profiles of OUE during a progressive cardiopulmonary exercise test. Cross-sectional. Healthy children between eight and 19 years of age (114 boys and 100 girls, mean ± SD age 12.7 ± 2.8 years) performed a maximal cardiopulmonary exercise test. Peak VO2 (VO2peak), ventilatory threshold and peak VE were determined. OUE was determined by the OUE plateau (OUEP), OUE at the ventilatory threshold (OUE@VT) and OUE slope (OUES). OUEP (42.4 ± 4.6) and OUE@VT (41.9 ± 4.7) were similar and less variable than OUES (2138 ± 703). OUEP correlated strongly with OUE@VT (r = 0.974); however, OUEP was weak-to-moderately correlated with VO2peak (r = 0.646), the ventilatory threshold (r = 0.548) and OUES (r = 0.589). OUES correlated strongly with VO2peak (r = 0.948) and the ventilatory threshold (r = 0.856). Reference centiles for OUEP show an almost linear increase from about 37 in eight-year olds to about 47 in 18-year olds, with no sex-difference. OUES increased from about 1400 in eight-year-old boys to approximately 3500 in 18-year-old boys. OUES increased from roughly 1250 in eight-year-old girls to about 2650 in 18-year-old girls. This study provides sex- and age-related normative values for both OUEP and OUES, which facilitates the interpretation of OUE in children. OUEP and OUES are objective and non-invasive cardiopulmonary exercise test parameters which do not require a maximal effort and might be indicative of cardiorespiratory function during exercise.

Oxygen uptake is more efficient in idiopathic pulmonary arterial hypertension than in chronic thromboembolic pulmonary hypertension.

The responses of oxygen uptake efficiency (OUE) during cardiopulmonary exercise training (CPET) have not been reported in patients with pulmonary hypertension. We aimed to investigate the differences in OUE between patients with idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Forty-four patients with IPAH and 29 patients with CTEPH were retrospectively enrolled into our study. All patients underwent right-heart catheterization, pulmonary function test and performed the 6-min walk test and CPET. We found that oxygen uptake efficiency plateau (OUEP) and oxygen uptake efficiency at anaerobic threshold (OUE@AT) was significantly higher in IPAH than that in CTEPH (both P = 0.002). However, patients with CTEPH had lower mean pulmonary artery pressure, pulmonary vascular resistance and transpulmonary gradient (all P < 0.05). The correlation between OUEP and heart rate at anaerobic threshold (HR_AT) was significant (r = 0.376, P < 0.05); however, no statistically significant correlation was found with ventilation at anaerobic threshold (VE_AT) (r = -0.074, P > 0.05) in patients with IPAH. In patients with CTEPH, both anaerobic threshold (r = 0.307, P > 0.05) and VE_AT (r = -0.709, P < 0.0001) were reduced. OUEP were higher in WHO functional class I/II patients than in WHO functional class III/IV patients (all P < 0.05). OUEP and OUE@AT are higher in IPAH than that in CTEPH not in proportion to haemodynamics, probably due to differences in cardiac function and pulmonary vascular occlusion. OUEP correlates well with the exercise capacity and the severity of the disease.

Clinical value of cardiopulmonary exercise testing derived oxygen uptake efficiency parameters in patients with end-stage chronic heart failure

To assess the cardiopulmonary exercise testing (CPET) derived performance of oxygen uptake and ventilation efficiency parameters, including oxygen uptake efficiency plateau (OUEP) , oxygen uptake efficiency slope (OUES), V·E/V·CO2 slope and lowest V·E/V·CO2, in patients with end-stage chronic heart failure (CHF) and evaluate their clinical value on monitoring cardiac function and hemodynamic status. A total of 26 end-stage CHF patients considered for heart transplantation were enrolled in this study. CPET, echocardiography and invasive hemodynamic examinations with Swan-Ganz flowing balloon catheter were performed. Correlation analysis was made between oxygen uptake and ventilation efficiency parameters from CPET and echocardiographic and hemodynamic parameters. OUEP and OUES showed good correlation with peak oxygen consumption (peak V·O2) (r = 0.535, P < 0.01;r = 0.840, P < 0.001). In end-stage CHF patients, the slope of OUEP with respect to peak V·O2 is about 32, but the slope of OUES with respect to peak V·O2 is only about 2. The difference was 16 times. The change of OUEP was more sensitive and significant than those of OUES and peak V·O2 (P < 0.05). OUEP, peak V·O2 (%pred), V·E/V·CO2 slope and lowest V·E/V·CO2 were all correlated well with non-invasive hemodynamic parameters peak cardiac output (r = 0.535, P < 0.01; r = 0.652, P < 0.001; r = -0.640, P < 0.001; r = -0.606, P = 0.001 respectively) and peak cardiac index (r = 0.556, P < 0.01;r = 0.772, P < 0.001; r = -0.641, P < 0.001; r = -0.620, P < 0.001 respectively) derived from CPET, but not correlated with invasive hemodynamic parameters cardiac output and cardiac index at rest (P > 0.05). Both peak V·O2 (%pred) and V·E/V·CO2 slope were significantly correlated with invasive hemodynamic parameters systolic pulmonary arterial pressure (r = -0.424, P < 0.05; r = 0.509, P < 0.01) and mean pulmonary arterial pressure (r = -0.479, P < 0.05; r = 0.405, P < 0.05). Peak V·O2 (%pred) was also significantly correlated with pulmonary capillary wedge pressure (r = -0.415, P < 0.05), and V·E/V·CO2 slope was significantly correlated with pulmonary vascular resistance (r = 0.429, P < 0.05). The oxygen uptake and ventilation efficiency parameters derived from CPET, including peak V·O2, OUEP, lowest V·E/V·CO2 and V·E/V·CO2 slope etc, are objectively monitoring and evaluating cardiac function and hemodynamic status. And they are useful for optimizing clinical management of patients with end-stage CHF.

The lowest VE/VCO2 ratio best identifies chronic thromboembolic pulmonary hypertension

IntroductionThe natural history of acute pulmonary embolism (PE) under treatment is about a gradual resolution of the thrombi, and uncommonly, the development of chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that ventilatory efficiency parameters during cardiopulmonary exercise testing (CPET) may be able to monitor the process and predict CTEPH. Methods15 patients rehabilitated from acute PE (total resolution of thrombi), 44 patients with chronic PE (with residual thrombi), 66 patients with CTEPH, and 36 sedentary healthy controls performed incremental CPET. ResultsThe lowest VE/VCO2 was higher in CTEPH patients than that in chronic PE and rehabilitated patients (43.4L/min vs 29.9L/min vs 27.1L/min, p<0.005). The VE/VCO2 slope (48.4L/min/L/min vs 29.9L/min/L/min vs 28.0L/min/L/min, p<0.005) and oxygen uptake efficiency plateau (OUEP) (37.1L/min vs 27.0L/min vs 25.2L/min, p<0.005) had the similar changes. In logistic regression analysis, the lowest VE/VCO2≥34.35L/min was the best predictor of CTEPH (OR 159.0, 95% CI 36.0-702.3, p<0.001). The lowest VE/VCO2 was higher in chronic PE patients compared with the controls (29.9L/min vs 26.5L/min, p<0.05), but there was no difference between the rehabilitated patients and the controls. In multiple linear regression analysis, the percentage of vascular obstruction by ventilation-perfusion lung scanning (PVO) was the most significant independent predictor for indices of ventilatory efficiency in chronic PE and rehabilitated patients. ConclusionsCTEPH is associated with weakened ventilatory efficiency. The lowest VE/VCO2 ratio has the best capability to predict CTEPH. Ventilatory inefficiency improves along with recovery of acute PE.

Usefulness of decrease in oxygen uptake efficiency to identify gas exchange abnormality in patients with idiopathic pulmonary arterial hypertension.

BackgroundDecline in oxygen uptake efficiency (OUE), especially during exercise, is found in patients with chronic heart failure. In this study we aimed to test the validity and usefulness of OUE in evaluating gas exchange abnormality of patients with idiopathic pulmonary arterial hypertension (IPAH).MethodsWe retrospectively investigated the cardiopulmonary exercise test (CPET) with gas exchange measurements in 32 patients with confirmed IPAH. All patients also had resting hemodynamic measurements and pulmonary function test (PFT). Sixteen healthy subjects, matched by age, sex, and body size were used as controls, also had CPET and PFT measurements.ResultsIn IPAH patients, the magnitude of absolute and percentage of predicted (%pred) oxygen uptake efficiency slope (OUES) and oxygen uptake efficiency plateau (OUEP), as well as several other CPET parameters, were strikingly worse than healthy subjects (P<0.0001). Pattern of changes in OUE in patients is similar to that in controls, In IPAH patients, OUE values at rest, warming up, anaerobic threshold and peak exercise were all significantly lower than in normal (P<0.0001). OUEP%pred, better than OUES%pred, correlated significantly with New York Heart Association (NYHA) functional Class (r = −0.724, P<0.005), Total Pulmonary Vascular Resistance (TPVR) (r = −0.694, P<0.005), diffusing capacity for carbon monoxide (DLCO) (r = 0.577, P<0.05), and the lowest ventilation versus CO2 output ratio during exercise (LowestV˙E/V˙CO2) (r = −0.902, P<0.0001). In addition, the coefficient of variation (COV) of OUEP was lower (20.9%) markedly than OUES (34.3%) (P<0.0001).ConclusionsIn patients with IPAH, OUES and OUEP are both significantly lower than the healthy subjects. OUEP is a better physiological parameter than OUES in evaluating the gas exchange abnormality of patients with IPAH.

Oxygen Uptake Efficiency Plateau Best Predicts Early Death in Heart Failure

The responses of oxygen uptake efficiency (ie, oxygen uptake/ventilation = VO(2)/VE) and its highest plateau (OUEP) during incremental cardiopulmonary exercise testing (CPET) in patients with chronic left heart failure (HF) have not been previously reported. We planned to test the hypothesis that OUEP during CPET is the best single predictor of early death in HF. We evaluated OUEP, slope of VO(2) to log(VE) (oxygen uptake efficiency slope), oscillatory breathing, and all usual resting and CPET measurements in 508 patients with low-ejection-fraction (< 35%) HF. Each had further evaluations at other sites, including cardiac catheterization. Outcomes were 6-month all-reason mortality and morbidity (death or > 24 h cardiac hospitalization). Statistical analyses included area under curve of receiver operating characteristics, ORs, univariate and multivariate Cox regression, and Kaplan-Meier plots. OUEP, which requires only moderate exercise, was often reduced in patients with HF. A low % predicted OUEP was the single best predictor of mortality (P < .0001), with an OR of 13.0 (P < .001). When combined with oscillatory breathing, the OR increased to 56.3, superior to all other resting or exercise parameters or combinations of parameters. Other statistical analyses and morbidity analysis confirmed those findings. OUEP is often reduced in patients with HF. Low % predicted OUEP (< 65% predicted) is the single best predictor of early death, better than any other CPET or other cardiovascular measurement. Paired with oscillatory breathing, it is even more powerful.

Oxygen uptake efficiency plateau: physiology and reference values

The relationship of oxygen uptake [Formula: see text] to ventilation [Formula: see text], i.e., oxygen uptake efficiency (OUE) is known to differ between normal subjects and patients with congestive heart failure. However, only the oxygen uptake efficiency slope (OUES, i.e., slope of [Formula: see text] has previously been reported. To understand the physiology and to improve the usefulness of OUE in assessing cardiovascular function, we analyzed the complete response pattern of OUE during entire incremental exercise tests and ascertained effect of age, body size, gender, fitness, and ergometer type on exercise OUE to generate reference values in normal healthy subjects. We investigated the effect of age, gender, and fitness on OUE using incremental cardiopulmonary exercise in 474 healthy subjects, age 17-78 years, of which 57 were highly fit. The final methods of OUE analysis were: (1) OUE plateau at the highest values (OUEP), (2) OUE at anaerobic threshold (OUE@AT), and (3) OUES using the entire exercise period. The OUEP and OUE@AT were similar, highly reproducible, less variable than the OUES (p < 0.0001), and unaffected by the study sites or types of ergometry. The resultant prediction equations from 417 normal subjects for men were OUEP (mL/L) = 42.18 - 0.189 × years + 0.036 × cm and OUES [L/min/log(L/min)] = -0.610 - 0.032 × years + 0.023 × cm + 0.008 × kg. For women, OUEP (mL/L) = 39.16 - 0.189 × years + 0.036 × cm and OUES [L/min/log(L/min)] = -1.178 - 0.032 × years + 0.023 × cm + 0.008 × kg. OUE@AT was similar to OUEP. Extreme fitness has a minimal effect on OUEP. OUEP is advantageous, since it measures maximal oxygen extraction from ventilated air but does not require high intensity exercise. The OUEP is a non-invasive parameter dependent only on age, gender, height, and cardiovascular health.

Oxygen Uptake Efficiency Plateau during Cardiopulmonary Exercise Testing Is Best Predictor of Early Death in Heart Failure Patients

Our goal was to identify better predictors of early death in patients with chronic left ventricular heart failure (CHF). Potential predictors, derived from cardiopulmonary exercise tests (CPX), were compared with other commonly used cardiovascular measurements. The prediction of early death in CHF patients remains challenging.METHODS &amp; RESULTS508 patients with CHF due to systolic dysfunction had resting cardiovascular measurements, six‐minute walking tests and CPX. The peak O2 uptake (VO2), peak O2 pulse, anaerobic threshold (AT), ratio of ventilation to CO2 output (VE/VCO2), VE‐vs‐VCO2 slope, and oxygen uptake efficiency plateau (OUEP, i.e. Highest VO2/VE) were ascertained. Outcomes were six‐month mortality (all cause death). During six‐month follow‐up, 19 patients died and 489 patients survived. The single best predictor of early mortality was the decreased OUEP (&lt;65%pred)(OR=12.8). The lowest VE/VCO2, VE‐vs‐VCO2 slope, peak VO2, AT and peak O2 pulse alone were strong predictors, their best OR values were 9.4, 7.6, 6.0, 5.1 and 4.3 respectively (p&lt;0.001). No non‐exercise measurements (i.e. NYHA, QRS duration, ejection fraction, blood pressure, cardiac output and stroke volume) discriminated mortality.CONCLUSIONSCPX parameters are powerful prognosticators of early mortality in CHF patients, especially the reduced OUEP.