Prognostic Value of Body Surface Area-Adjusted Oxygen Uptake Efficiency Slope in Heart Failure Patients.

Background: COVID-19 has been associated with a higher risk of developing heart failure (HF). Among the parameters derived from cardiopulmonary exercise testing (CPET), oxygen uptake efficiency slope (OUES) has become one of the most important parameters for predicting the prognosis of HF patients. However, the clinical utilization of OUES is limited owing to its variation with patient height and weight. This study aimed to evaluate the prognostic value of body surface area-adjusted OUES (OUES/BSA) in adults with HF. Methods: Thirty-six HF patients (mean age, 57 ± 12 years; 30 men) undergoing CPET between July 2019 and May 2020 who were followed up for 12 months were enrolled. The endpoints were major cardiovascular (CV) events, including hospitalization due to acute decompensated HF, left ventricular assist device implantation, heart transplantation, and cardiovascular-related death. We analyzed the correlations between clinical/CPET variables and major CV events. Results: Among the analyzed CPET variables, OUES/BSA had better correlation with maximal oxygen uptake (VO2max) than other variables. In univariate Cox proportional analysis, OUES/BSA and peak VO2 were both significant independent prognostic factors. The cutoff value of OUES/BSA was 595 ml/min/m2 with an area under the curve of 0.929. The patients with OUES/BSA < 595 ml/min/m2 had a lower CV event-free survival rate at 12 months of follow-up compared with the other group (33.3% and 100%, respectively; log-rank test, p < 0.001). Conclusions: BSA-adjusted OUES is an effective independent predictor for prognosis in HF patients and can be an alternative to peak VO2 for risk stratification in HF patients, regardless of exercise intensity. However, further large-scale studies are required to validate our findings.

Below or all the way to the peak? Oxygen uptake efficiency slope as the index of cardiorespiratory response to exercise-the NOODLE study.

Background: The ratio of oxygen uptake (VO2) to minute ventilation (VE) is described as the oxygen uptake efficiency slope (OUES). OUES has been suggested as a valuable submaximal cardiorespiratory index; however, its characteristics in endurance athletes remain unknown. In this study, we a) investigated OUES between different time intervals, b) assessed their prediction power for VO2peak, and c) derived new prediction equations for OUES tailored for well-trained individuals. Materials and Methods: A total of 77 male (age = 21.4 ± 4.8 yrs; BMI = 22.1 ± 1.6 kg·m-2; peak oxygen uptake = 4.40 ± 0.64 L·min-1) and 63 female individuals (age = 23.4 ± 4.3 yrs; BMI = 23.1 ± 1.6 kg·m-2; peak oxygen uptake = 3.21 ± 0.48 L·min-1) underwent the cycling cardiopulmonary exercise test. OUES was measured at 75%, 90%, and 100% of exercise duration. Prediction power and new models were derived with the multiple linear regression method. Results: In male subjects, OUES [mL·min-1/L·min-1] from 75% = 4.53 ± 0.90, from 90% = 4.52 ± 0.91, and from 100% = 4.41 ± 0.87. In female subjects, OUES [mL·min-1/L·min-1] from 75% = 3.50 ± 0.65, from 90% = 3.49 ± 0.62, and from 100% = 3.41 ± 0.58. OUES did not differ between time intervals in male (p = 0.65) and female individuals (p = 0.69). OUES strongly predicts peak VO2 independently from the measuring interval (ß = 0.71-0.80; R 2 = 0.50-0.63). The prediction model designed for elite athletes was OUES [mL·min-1/L·min-1] = -1.54 + 2.99; BSA [m2]-0.0014; (age [in years]; sex [1 = male, 2 = female]) (R 2 = 0.36). Conclusion: OUES enables an accurate prediction of peak cardiorespiratory fitness in elite endurance athletes. OUES is a feasible alternative to maximal exercise testing. A new prediction equation should be used for highly trained individuals. Physicians should understand OUES physiology to properly assess the cardiorespiratory response to exercise in athletic cohorts.

The oxygen uptake efficiency slope in adults with CHD: group validity.

The maximal oxygen uptake (V02 max) is a well-validated measure of cardiorespiratory function that is calculated during a maximal cardiopulmonary exercise test. V02 max enables physicians to objectively assess cardiopulmonary function to aid in decision-making for patients with CHD. A significant proportion of these patients however are unable to achieve a maximal exercise test, and as such, there is a need for reliable submaximal predictors of cardiorespiratory reserve.The oxygen uptake efficiency slope represents a measure of how effectively oxygen is extracted from the lungs and taken into the body and can be calculated from a submaximal exercise test. Its reliability as a predictor of cardiorespiratory reserve has been validated in various patient populations, but there is limited evidence for its validity in adult patients with CHD.Retrospective analysis of cardiopulmonary exercise test data in 238 consecutive patients with CHD who completed a maximal cardiopulmonary exercise test at our tertiary cardiology centre demonstrated a strong correlation between peak V02 and the oxygen uptake efficiency slope (0.936). A strong correlation with peak V02 was also demonstrated when oxygen uptake efficiency slope was calculated at ventilatory anaerobic threshold (OUESVAT), 75% (OUES75), and 90% (OUES90) of the test (0.833, 0.905, 0.927 respectively).In adult patients with CHD who are unable to complete a maximal cardiopulmonary exercise test, the oxygen uptake efficiency slope is a reliable indicator of cardiopulmonary fitness which correlates strongly with peak V02 at or beyond the ventilatory anaerobic threshold. Further research is required to validate the findings in patients with less common anatomies and to assess the relationship between the oxygen uptake efficiency slope and mortality.

A retrospective analysis of the association of effort-independent cardiopulmonary exercise test variables with postoperative complications in patients who underwent elective colorectal surgery.

PURPOSE: This study aimed to investigate the association of effort-independent variables derived from the preoperative cardiopulmonary exercise test (CPET) with 30-day postoperative complications after elective colorectal surgery. METHODS: A multicenter (n=4) retrospective explorative study was performed using data of patients who completed a preoperative CPET and underwent elective colorectal surgery. The preoperative slope of the relation between minute ventilation and carbon dioxide production (VE/VCO2-slope) and the oxygen uptake efficiency slope (OUES), as well as 30-day postoperative complications, were assessed. Multivariable logistic regression analyses and receiver operating characteristic (ROC) curves were used to investigate the prognostic value of the relationship between these preoperative CPET-derived effort-independent variables and postoperative complications. RESULTS: Data from 102 patients (60.1% males) with a median age of 72.0 (interquartile range 67.8-77.4) years were analyzed. Forty-four patients (43.1%) had one or more postoperative complications (of which 52.3% general and 77.3% surgical complications). Merely 10 (9.8%) patients had a general complication only. In multivariate analysis adjusted for surgical approach (open versus minimally invasive surgery), the VE/VCO2-slope (odds ratio (OR) 1.08, confidence interval (CI) 1.02-1.16) and OUES (OR 0.94, CI 0.89-1.00) were statistically significant associated with the occurrence of 30-day postoperative complications. CONCLUSION: The effort-independent VE/VCO2-slope and OUES might be used to assist in future preoperative risk assessment and could especially be of added value in patients who are unable or unwilling to deliver a maximal cardiorespiratory effort. Future research should reveal the predictive value of these variables individually and/or in combination with other prognostic (CPET-derived) variables for postoperative complications. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT05331196.

Respiratory Muscle Function and Exercise Performance in Adult Patients with Fontan Circulation.

At rest, a good Fontan circulation can provide a normal cardiac output (CO). However, as a consequence of its unique hemodynamic nature, the limitations of the Fontan circuit are exposed during exercise. We aimed to provide a comprehensive assessment of the pathophysiology of exercise in adult Fontan patients (FPs) and identify factors limiting their functional capacity (FC). In a single-center study conducted in 37 FPs aged ≥16 years and 19 healthy-controls (HCs) who underwent CPET on a cycle ergometer in February and March 2022, the mean peakVO2 was 21 ± 5.4 mL/kg/min, which was 55% of the predicted value. Morphologically, the left single ventricle showed a higher peakVO2% predicted value (57.4 ± 14.4% vs. 43.4 ± 8.1%, p = 0.045). The factors associated with low peakVO2 values were an early flattened or descending O2 pulse at maximal exertion (52 ± 14% vs. 62 ± 12.5, p = 0.04 and 47.6 ± 9% vs. 60 ± 14, p = 0.018, respectively) and chronotropic insufficiency (53 ± 12% vs. 69.8 ± 20%, p = 0.008). The OUES was found to be a useful parameter to assess the FC in FPs in maximal and submaximal exercise testing. A strong positive correlation was observed between the %OUES and peakVO2%predicted (r = 0.726, p > 0.001). The lung function was impaired in the FPs, mostly with a mild restrictive pattern (56.8%). The FPs showed lower inspiratory muscle strength compared to the HCs but it was not statistically associated with either the peakVO2 or VE/VCO2 slope. Regular intense physical activity improves one's FC. Although FPs have inspiratory muscle weakness, its impact on their FC is unclear. The peakVO2% predicted grew progressively higher as the level of physical activity increased (low level 49.5 ± 14%, moderate level 55 ± 12%, intense level 69 ± 20%).

The Pre-Discharge Oxygen Uptake Efficiency Slope Predicts One-Year Cardiovascular Events in Acute Decompensated Heart Failure Patients.

(1) Background: Heart failure is a complex disease leading to functional disability. Cardiopulmonary exercise testing (CPET) is the gold standard in assessing aerobic capacity and formulating function-based prognostic stratification; however, patients with acute heart failure after medical treatment usually remain with markedly reduced exercise capacity, leading to early termination of CPET with submaximal testing results. The current study aimed to assess the cardiorespiratory fitness and characteristics of CPET variables of patients after acute heart failure treatment and determine potential CPET variables with prognostic value. (2) Methods: We recruited patients during hospitalization after management of acute heart failure, and pre-discharge CPET was performed. All enrolled patients were followed for one year for major adverse cardiovascular events (MACE). (3) Results: 85 patients were enrolled, with average left ventricular ejection fraction of 30.52%, and peak oxygen consumption of 10.85 mL/min/kg at baseline. The one-year MACE was 50%. Oxygen uptake efficiency slope (OUES) was a significant event predictor, with lower one-year MACE in those with OUES ≥ 1.25 (p < 0.001). Cox regression analysis showed a 5.421-fold increased risk of MACE in those with OUES < 1.25 (p = 0.004). (4) Conclusions: The current results suggested OUES is a significant prognostic indicator in patients with acute heart failure. This also emphasized the critical role of CPET in patients with heart failure for prognostic stratification.

Cardiopulmonary exercise test in patients with refractory angina: functional and ischemic evaluation.

OBJECTIVES: Refractory angina (RA) is a chronic condition clinically characterized by low effort tolerance; therefore, physical stress testing is not usually requested for these patients. Cardiopulmonary exercise testing (CPET) is considered a gold standard examination for functional capacity evaluation, even in submaximal tests, and it has gained great prominence in detecting ischemia. The authors aimed to determine cardiorespiratory capacity by using the oxygen consumption efficiency slope (OUES) in patients with refractory angina. The authors also studied the O2 pulse response by CPET and the association of ischemic changes with contractile modifications by exercise stress echocardiography (ESE). METHODS: Thirty-one patients of both sexes, aged 45 to 75 years, with symptomatic (Canadian Cardiovascular Society class II to IV) angina who underwent CPET on a treadmill and exercise stress echocardiography on a lower limb cycle ergometer were studied. ClinicalTrials.gov: NCT03218891. RESULTS: The patients had low cardiorespiratory capacity (OUES of 1.74 ± 0.4 L/min; 63.9±14.7% of predicted), and 77% of patients had a flattening or drop in O2 pulse response. There was a direct association between Heart Rate (HR) at the onset of myocardial ischemia detected by ESE and HR at the onset of flattening or drop in oxygen pulse response detected by CPET (R = 0.48; p = 0.019). CONCLUSION: Patients with refractory angina demonstrate low cardiorespiratory capacity. CPET shows good sensitivity for detecting abnormal cardiovascular response in these patients with a significant relationship between flattening O2 pulse response during CEPT and contractile alterations detected by exercise stress echocardiography.

Oxygen Uptake Efficiency Slope Predicts Adverse Outcome Following Atrial Switch Procedure.

Prior to the 1990s, d-TGA was palliated with the atrial switch procedure resulting in a systemic right ventricle associated with significant long-term morbidity and mortality. Determining the optimal timing of heart transplantation (HT) in these patients has been difficult. While cardiopulmonary exercise testing (CPET) is commonly used to try and risk stratify these patients, traditional exercise parameters have lacked the sensitivity and specificity to assess long-term risk. We sought to assess changes in exercise parameters over time in order to determine if any CPET parameter or combination of parameters could reliably identify risk for adverse outcome in this patient group. A retrospective review of serial CPET for 40 patients over 17 years was completed. Patients with adverse event within 6 months prior to CPET were noted. CPET parameters were compared and linear mixed model regression with repeated measures was performed on serial tests for longitudinal assessment. The linear mixed model regression identified OUES indexed to BSA to be the most sensitive parameter in identifying patients at risk of adverse event and became a stronger predictor of adverse event when combined with peak heart rate. CPET is useful in identifying patients with atrial switch at increased risk of adverse outcome. Indexed OUES and peak heart rate are better prognostic indicators than VO2 and VE/VCO2.

Cardiopulmonary exercise test in patients with refractory angina: functional and ischemic evaluation

Abstract Objectives Refractory angina (RA) is a chronic condition clinically characterized by low effort tolerance; therefore, physical stress testing is not usually requested for these patients. Cardiopulmonary exercise testing (CPET) is considered a gold standard examination for functional capacity evaluation, even in submaximal tests, and it has gained great prominence in detecting ischemia. The authors aimed to determine cardiorespiratory capacity by using the oxygen consumption efficiency slope (OUES) in patients with refractory angina. The authors also studied the O2 pulse response by CPET and the association of ischemic changes with contractile modifications by exercise stress echocardiography (ESE). Methods Thirty-one patients of both sexes, aged 45 to 75 years, with symptomatic (Canadian Cardiovascular Society class II to IV) angina who underwent CPET on a treadmill and exercise stress echocardiography on a lower limb cycle ergometer were studied. ClinicalTrials.gov: NCT03218891. Results The patients had low cardiorespiratory capacity (OUES of 1.74 ± 0.4 L/min; 63.9±14.7% of predicted), and 77% of patients had a flattening or drop in O2 pulse response. There was a direct association between Heart Rate (HR) at the onset of myocardial ischemia detected by ESE and HR at the onset of flattening or drop in oxygen pulse response detected by CPET (R = 0.48; p = 0.019). Conclusion Patients with refractory angina demonstrate low cardiorespiratory capacity. CPET shows good sensitivity for detecting abnormal cardiovascular response in these patients with a significant relationship between flattening O2 pulse response during CEPT and contractile alterations detected by exercise stress echocardiography. Highlights OUES analysis is useful for assessing functional capacity in refractory angina. O2 pulse curve is correlated with contractile alterations in exercise echocardiogram. Cardiopulmonary exercise test is useful toll in patients with refractory angina.

The Relationship between Resistance Exercise Performance and Ventilatory Efficiency after Beetroot Juice Intake in Well-Trained Athletes.

The assessment of ventilatory efficiency is critical to understanding the matching of ventilation (VE) and perfusion in the lungs during exercise. This study aimed to establish a causal physiological relationship between ventilatory efficiency and resistance exercise performance after beetroot juice (BJ) intake. Eleven well-trained males performed a resistance exercise test after drinking 140 mL of BJ (~12.8 mmol NO3-) or a placebo (PL). Ventilatory efficiency was assessed by the VE•VCO2-1 slope, the oxygen uptake efficiency slope and the partial pressure of end-tidal carbon dioxide (PetCO2). The two experimental conditions were controlled using a randomized, double-blind crossover design. The resistance exercise test involved repeating the same routine twice, which consisted of wall ball shots plus a full squat (FS) with a 3 min rest or without a rest between the two exercises. A higher weight lifted was detected in the FS exercise after BJ intake compared with the PL during the first routine (p = 0.004). BJ improved the VE•VCO2-1 slope and the PetCO2 during the FS exercise in the first routine and at rest (p < 0.05). BJ intake improved the VE•VCO2-1 slope and the PetCO2 coinciding with the resistance exercise performance. The ergogenic effect of BJ could be induced under aerobic conditions at rest.

A novel exercise testing algorithm to diagnose mitochondrial myopathy.

INTRODUCTION: Oxygen uptake efficiency slope (OUES) is a noninvasive cardiopulmonary exercise testing (CPET) measurement based on oxygen uptake (V˙O2 ) and minute ventilation (V˙E) and is a marker of the efficiency of oxygen utilization by the body. However, it has not been studied in mitochondrial disorders. We explored noninvasive CPET parameters, including OUES, as a way to reliably diagnose mitochondrial myopathy. METHODS: We performed cycle ergometer maximal exercise testing on definite and suspected mitochondrial myopathy subjects (MM-D and MM-S) and their age- and sex-matched controls. OUES was corrected for body surface area (OUES/BSA) to eliminate the effect of body size. RESULTS: A total of 40 participants, including 20 MM-D (n = 13; 6 males; aged 14-64 years) and 7 MM-S (5 males, aged 11-30 years) subjects and 20 controls, completed the study. MM-D subjects showed lower aerobic fitness than controls. OUES/BSA was lower in MM-D subjects, suggesting inefficient oxygen utilization. Area under the curve (AUC) and 95% confidence interval (CI) for OUES/BSA (AUC, 0.91; 95% CI, 0.80-1.00), peak V˙O2 percent predicted (AUC, 0.95; 95% CI, 0.86-1.00), and V˙O2 /work slope (AUC, 0.94; 95% CI, 0.85-1.00) showed excellent ability to diagnose mitochondrial myopathy in MM-D subjects. We applied a diagnostic approach based on the parameters just noted to MM-S subjects and their controls and were able to support or disprove the diagnosis of mitochondrial myopathy. DISCUSSION: We proposed and applied an approach based on the aformentioned three CPET parameters to diagnose mitochondrial myopathy reliably and found it to be clinically useful.

Oxygen Uptake Efficiency Slope is Strongly Correlated to VO2peak Long-Term After Arterial Switch Operation.

After the arterial switch operation (ASO) for transposition of the great arteries (TGA), many patients have an impaired exercise tolerance. Exercise tolerance is determined with cardiopulmonary exercise testing by peak oxygen uptake (VO2peak). Unlike VO2peak, the oxygen uptake efficiency slope (OUES) does not require a maximal effort for interpretation. The value of OUES has not been assessed in a large group of patients after ASO. The purpose of this study was to determine OUES and VO2peak, evaluate its interrelationship and assess whether exercise tolerance is related to ventricular function after ASO. A cardiopulmonary exercise testing, assessment of physical activity score and transthoracic echocardiography (fractional shortening and left/right ventricular global longitudinal peak strain) were performed to 48 patients after ASO. Median age at follow-up after ASO was 16.0 (IQR 13.0-18.0) years. Shortening fraction was normal (36 ± 6%). Left and right global longitudinal peak strain were reduced: 15.1 ± 2.4% and 19.5 ± 4.5%. This group of patients showed lower values for all cardiopulmonary exercise testing parameters compared to the reference values: mean VO2peak% 75% (95% CI 72-77) and mean OUES% 82(95% CI 77-87); without significant differences between subtypes of TGA. A strong-to-excellent correlation between the VO2peak and OUES was found (absolute values: R = 0.90, p < 0.001; normalized values: R = 0.79, p < 0.001). No correlation was found between cardiopulmonary exercise testing results and left ventricle function parameters. In conclusion, OUES and VO2peak were lower in patients after ASO compared to reference values but are strongly correlated, making OUES a valuable tool to use in this patient group when maximal effort is not achievable.

Maximal oxygen consumption and oxygen uptake efficiency in adolescent males.

BACKGROUND/OBJECTIVE: Measures 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. METHODS: Sixty-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. RESULTS: Limits 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). CONCLUSION: The OUES and OUEP do not accurately predict V̇O2max in male adolescents and should not replace V̇O2max when assessing CRF in this population.

Cardiopulmonary exercise testing in severe osteoarthritis: a crossover comparison of four exercise modalities.

Cardiopulmonary exercise testing is performed increasingly for cardiorespiratory fitness assessment and pre-operative risk stratification. Lower limb osteoarthritis is a common comorbidity in surgical patients, meaning traditional cycle ergometry-based cardiopulmonary exercise testing is difficult. The purpose of this study was to compare cardiopulmonary exercise testing variables and subjective responses in four different exercise modalities. In this crossover study, 15 patients with osteoarthritis scheduled for total hip or knee arthroplasty (mean (SD) age 68 (7) years; body mass index 31.4 (4.1) kg.m-2 ) completed cardiopulmonary exercise testing on a treadmill, elliptical cross-trainer, cycle and arm ergometer. Mean (SD) peak oxygen consumption was 20-30% greater on the lower limb modalities (treadmill 21.5 (4.6) (p < 0.001); elliptical cross-trainer (21.2 (4.1) (p < 0.001); and cycle ergometer (19.4 (4.2) ml.min-1 .kg-1 (p = 0.001), respectively) than on the arm ergometer (15.7 (3.7) ml.min-1 .kg-1 ). Anaerobic threshold was 25-50% greater on the lower limb modalities (treadmill 13.5 (3.1) (p < 0.001); elliptical cross-trainer 14.6 (3.0) (p < 0.001); and cycle ergometer 10.7 (2.9) (p = 0.003)) compared with the arm ergometer (8.4 (1.7) ml.min-1 .kg-1 ). The median (95%CI) difference between pre-exercise and peak-exercise pain scores was greater for tests on the treadmill (2.0 (0.0-5.0) (p = 0.001); elliptical cross-trainer (3.0 (2.0-4.0) (p = 0.001); and cycle ergometer (3.0 (1.0-5.0) (p = 0.001)), compared with the arm ergometer (0.0 (0.0-1.0) (p = 0.406)). Despite greater peak exercise pain, cardiopulmonary exercise testing modalities utilising the lower limbs affected by osteoarthritis elicited higher peak oxygen consumption and anaerobic threshold values compared with arm ergometry.

Collective effects of age, sex, genotype, and cognitive status on fitness outcomes.

INTRODUCTION: Individuals with Alzheimer's disease (AD) broadly exhibit lower cardiorespiratory fitness (CRF) compared to cognitively healthy older adults. Other factors, such as increasing age and female sex, are also known to track with lower CRF levels. However, it is unclear how these factors together with AD diagnosis and genetic risk (apolipoprotein e4 ; APOE4) collectively affect CRF. METHODS: Our primary objective was to characterize the collective relationship of age, sex, APOE4 carrier status , and cognitive status (nondemented or AD) with two commonly reported CRF outcomes, VO2 max and oxygen uptake efficiency slope (OUES). To interrogate the unique and combined effect of age, sex, APOE4, and cognitive status on CRF, we pooled multiple datasets and tested several statistical models allowing all possible interactions. RESULTS: AD diagnosis was consistently associated with lower maximal CRF, which declined with increasing age. APOE4 was also associated with lower maximal CRF (VO2max), but only in male subjects. Submaximal CRF (OUES) was lower in APOE4 carriers of both sexes, although this difference converged in male subjects with advancing age. DISCUSSION: This multi-cohort analysis (n = 304) suggests that APOE4 carrier status and sex are important considerations for studies that evaluate maximal and submaximal CRF.

Contributions of residual hypoxemia to exercise hyperventilation in Fontan patients.

It is unsettled whether increased exercise ventilation in Fontan subjects is due to increased pulmonary dead space or augmented ventilatory drive. Twenty-six Fontan patients underwent symptom-limited treadmill cardiopulmonary exercise testing. Two groups of age- and sex- matched subjects served as controls: the biventricularly repaired (Bi, n = 18), and the "true" control (C, n = 29) groups. Peak oxygen uptake (V̇O2peak) was not different among groups (41.0 +/- 8.4 ml/min/kg, 43.5 +/- 6.6 ml/min/kg, and 45.9 +/- 11.6 ml/min/kg for Fontan, Bi, and C groups, respectively, p = 0.16). Fontan subjects, however, showed steeper alveolar ventilation/carbon-dioxide (V̇A/V̇CO2) regression slope (35.5 +/- 5.3, 28.7 +/- 3.8, and 29.5 +/- 3.0 l/ml, for Fontan, Bi, and C groups, respectively, p<0.0001), and lower end-expiratory carbon-dioxide fraction (FetCO2VAT) at ventilatory threshold (VAT) (4.4 +/- 0.5%, 5.5 +/- 0.5%, and 5.5 +/- 0.4%, for Fontan, Bi, and C groups, respectively, p<0.001). The dead-space ventilation fraction at VAT was similar among groups (0.33 +/- 0.06, 0.33 +/- 0.04, 0.35 +/- 0.05 for Fontan, Bi, and C groups, respectively, p = 0.54). In Fontan subjects, arterial oxygen saturation at rest (SaO2rest) was correlated with V̇A/V̇CO2 regression slope (r = -0.41, p = 0.04) and with FetCO2VAT (p = -0.53, p<0.01). We conclude that Fontan patients show exercise hyperventilation due to augmented central and/or peripheral ventilatory drive, which is further augmented by residual hypoxemia.

Functional capacity and ventilatory efficiency are preserved in well-controlled people living with human immunodeficiency virus/acquired immunodeficiency syndrome.

To verify and compare the responses of the cardiopulmonary variables to the incremental test in physically inactive people living with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (PLWHA) with well-controlled disease and physically inactive healthy subjects (non-HIV/AIDS). Participants performed a cardiopulmonary exercise test (CPX) on a treadmill. Data were analyzed using the Mann-Whitney test and Spearman correlation. Nine PLWHA (5 women) and 9 non-HIV/AIDS gender and activity level-matched controls were included in the data analysis. Data are expressed in median (range). No difference was shown in the PLWHA group when compared to the control group in functional capacity (peak oxygen consumption [VO2peak]: 29.9 (20.9-36.4) mL/kg/min vs. 32.2 (24.5-39.4) mL/kg/min) and ventilatory efficiency (oxygen uptake efficiency slope [OUES]: 2,058 [1,474-3,204] vs. 2,612 [1,383-4,119]; minute ventilation carbon dioxide production slope: 27.4 [22.5-33.6] vs. 27.5 [20.4-38.1]). The results are also similar to maximal heart rate, oxygen pulse, gas exchange threshold, respiratory compensation point, heart rate recovery, and half-time of VO2peak recovery. OUES had a strong correlation with VO2peak in the PLWHA group (r s =0.70, P=0.04) and control group (r s =0.78, P=0.02). The results of this study indicate that functional capacity and ventilatory efficiency in PLWHA with well-controlled disease are preserved and are not different from sedentary subjects. In this sense, when CPX is unavailable, the aerobic assessment and prescription could be based on simpler procedures used in healthy subjects.

[Relationships between percentage of skeletal muscle mass and cardiorespiratory fitness in elderly patients with coronary heart disease].

Objective: To determine the relative percentage of skeletal muscle mass (SMM) in elderly patients with coronary heart disease, analyse the relationship between percentage of SMM and cardiorespiratory fitness (CRF), predict exercise capacity and cardiac reserve. Methods: Patients aged 65 years and over after PCI, receiving cardiopulmonary exercise testing (CPET) during February 2014 to December 2016 in Department of Cardiology at Peking University Third Hospital were enrolled.All patients' basic data, percentage of SMM and CPET related parameters, including peak oxygen uptake (VO(2)peak), oxygen pulse (VO(2)/HR), oxygen uptake efficiency slope (OUES) and other cardiorespiratory endurance indicators were collected, to do correlation analysis. Results: There were 402 patients enrolled, with average age (71±5) years, including 283 cases of male (70.40%) and 119 cases of female patients (29.60%). There were 62 patients with acute myocardial infarction (15.42%), 113 patients with old myocardial infarction (28.11%), and 227 patients diagnosed with angina pectoris (56.47%). The percentage of SMM was correlated to CRF.The percentage of SMM[97.00 (92.05, 102.10)%] and VO(2)/HR (r=0.231, P<0.001) and OUES (r=0.264, P<0.001) were positively correlated.Body mass index was negatively correlated with VO(2)peak(r=-0.162, P=0.001). Visceral fat area (VFA) was also negatively correlated with VO(2)peak(r=-0.126, P=0.016). Multiple linear regression analysis showed that Body mass index and VFA were negatively correlated with VO(2)peak (r=-0.204, P=0.014; r=-0.031, P=0.013). The percentage of SMM was positively independently correlated with OUES(r=11.020, P<0.001). Conclusions: Muscle content is positively correlated with exercise capacity of patients.The percentage of skeletal muscle mass determines the core index of cardiorespiratory fitness, such as the slope of oxygen pulse and oxygen uptake efficiency.These indexes can be used as an important criterion for predicting and guiding rehabilitation exercise in patients with coronary heart disease.

Oxygen uptake efficiency slope during exercise in adults with Down syndrome.

BACKGROUND: Persons with Down syndrome (DS) have low aerobic exercise capacity. The present authors sought to compare the oxygen uptake efficiency slope (OUES) between adults with and without DS performing graded exercise testing (GXT) and to investigate its relationship with peak oxygen uptake (VO2peak ) in both groups of participants. METHOD: Twenty-three participants with DS and 24 non-disabled controls performed GXT with VO2 measurements. OUES was calculated from data of the first 75%, 90% and 100% GXT time. Multiple linear regression analyses were computed to explore associations between the independent (OUES and DS) and the dependent variables (VO2peak ). RESULTS: VO2peak , GXT time and OUES were lower in participants with DS (p < .05). OUES and DS explained 69.3% of the variance in VO2peak . CONCLUSIONS: Our findings show that OUES values are lower in persons with DS. Additionally, it was shown that OUES has predictive value for VO2peak estimations in DS.

An Objective Method to Accurately Measure Cardiorespiratory Fitness in Older Adults Who Cannot Satisfy Widely Used Oxygen Consumption Criteria.

Cardiorespiratory fitness (CRF) is routinely investigated in older adults; however, the most appropriate CRF measure to use for this population has received inadequate attention. This study aimed to 1) evaluate the reliability and validity of the oxygen uptake efficiency slope (OUES) as a sub-maximal measurement of CRF; 2) examine demographic, risk-factor, and exercise testing differences in older adults who satisfied standardized criteria for a peak oxygen consumption (V̇O2peak) test compared to those who did not; and 3) determine the difference between directly measured V̇O2peak values and OUES-predicted V̇O2peak values. One hundred ten enrollees from the Wisconsin Registry for Alzheimer's Prevention participated in this study. Participants performed a graded maximal exercise test and wore an accelerometer for 7 days. For each participant, the OUES was calculated at 75%, 90%, and 100% of exercise duration. V̇O2peak was recorded at peak effort, and one week of physical activity behavior was measured. OUES values calculated at separate relative exercise durations displayed excellent reliability (ICC = 0.995; p < 0.001), and were strongly correlated with V̇O2peak (rrange = 0.801-0.909; p < 0.001). As hypothesized, participants who did not satisfy V̇O2peak criteria were significantly older than those who satisfied criteria (p = 0.049) and attained a directly measured V̇O2peak that was 2.31 mL·kg·min-1 less than the value that was predicted by OUES V̇O2peak (p = 0.003). Older adults are less likely to satisfy V̇O2peak criteria, which results in an underestimation of their CRF. Without adhering to standardized criteria, V̇O2peak measurement error may lead to misinterpretation of CRF and age-related associations. Here, we conclude that OUES is a reliable, valid measurement of CRF which does not require achievement of standardized criteria.