Clinical Cardiopulmonary Exercise Testing Research Articles

Comparison of Cardiorespiratory Fitness Prediction Equations and Generation of New Predictive Model for Patients with Obesity.

Cardiorespiratory fitness (CRF) is a critical marker of overall health and a key predictor of morbidity and mortality, but the existing prediction equations for CRF are primarily derived from general populations and may not be suitable for patients with obesity. Predicted CRF from different non-exercise prediction equations was compared with measured CRF of patients with obesity who underwent maximal cardiopulmonary exercise testing (CPET). Multiple linear regression was used to develop a population-specific nonexercise CRF prediction model for treadmill exercise including age, sex, weight, height, and physical activity level as determinants. Six hundred sixty patients underwent CPET during the study period. Within the entire cohort, R2 values had a range of 0.24 to 0.46. Predicted CRF was statistically different from measured CRF for 19 of the 21 included equations. Only 50% of patients were correctly classified into the measured CRF categories according to predicted CRF. A multiple model for CRF prediction (mL·min -1 ) was generated ( R2 = 0.78) and validated using two cross-validation methods. Most used equations provide inaccurate estimates of CRF in patients with obesity, particularly in cases of severe obesity and low CRF. Therefore, a new prediction equation was developed and validated specifically for patients with obesity, offering a more precise tool for clinical CPET interpretation and risk stratification in this population.

Maximal Exercise Tolerance, Objective Trunk Strength, and Mobility Measurements in Axial Spondyloarthritis.

Although exercise therapy is safe, effective, and recommended as a nonpharmacological treatment for axial spondyloarthritis (axSpA), there is a lack of guidelines regarding type and dosage. Insufficient knowledge about physical and physiological variables makes designing effective exercise programs challenging. Therefore, the goal of this study was to simultaneously assess trunk strength, spinal mobility, and the cardiorespiratory fitness of patients with axSpA. In a cross-sectional study, 58 patients with axSpA (mean age 40.8 yrs, 50% male, mean symptom duration 10.3 yrs) performed maximal cervical and trunk mobility and isometric strength tests in all planes (using David Back Concept devices) and a maximal cardiopulmonary bicycle exercise test (n = 25). Mobility and strength data were compared to healthy reference data. Cut-off values for clinical cardiopulmonary exercise testing interpretation were used to judge normality. Patients were compared based on radiographic involvement and symptom duration. Both strength (P ≤ 0.02) and mobility (P ≤ 0.001) were significantly lower for the patients with axSpA compared to the reference. Strength deficits were comparable between the radiographic and nonradiographic groups (P > 0.05, except trunk extension [P = 0.03]), whereas mobility showed higher deficits in the radiographic group (cervical extension [P = 0.02] and rotation [P = 0.01], and trunk extension [P = 0.03] and rotation [P = 0.03]), regardless of symptom duration. Similarly, symptom duration positively affected oxygen pulse (P = 0.03), relative anaerobic threshold (P = 0.02), and aerobic capacity (P = 0.02). In patients with axSpA, strength is more affected than mobility when compared to healthy controls. Likewise, mainly the metabolic component of aerobic capacity is impaired, affecting cardiopulmonary fitness. These findings indicate that future personalized exercise programs in patients with axSpA should incorporate exercises for cardiopulmonary fitness next to strength and mobility training.

A Reference Equation for Peak Oxygen Uptake for Pediatric Patients Who Undergo Treadmill Cardiopulmonary Exercise Testing

Pediatric patients are often referred to cardiopulmonary exercise testing (CPET) laboratories for assessment of exercise-related symptoms. For clinicians to understand results in the context of performance relative to peers, adequate fitness-based prediction equations must be available. However, reference equations for prediction of peak oxygen uptake (VO2peak) in pediatrics are largely developed from field-based testing, and equations derived from CPET are primarily developed using adult data. Our objective was to develop a pediatric reference equation for VO2peak. Clinical CPET data from a validation cohort of 1,383 pediatric patients aged 6 to 18years who achieved a peak respiratory exchange ratio ≥1.00 were analyzed to identify clinical and exercise testing factors that contributed to the prediction of VO2peak from tests performed using the Bruce protocol. The resultant prediction equation was applied to a cross-validation cohort of 1,367 pediatric patients. Exercise duration, gender, weight, and age contributed to the prediction of VO2peak, generating the following prediction equation: (R2=0.645, p <0.001, standard error of the estimate=6.19ml/kg/min): VO2peak (ml/kg/min) =16.411+ 3.423 (exercise duration [minutes]) - 5.145 (gender [0=male, 1=female]) - 0.121 (weight [kg])+0.179 (age [years]). This equation was stable across the age range included in the present study, with differences ≤0.5ml/kg/min between mean measured and predicted VO2peak in all age groups. In conclusion, this study represents what we believe is the largest pediatric CPET-derived VO2peak prediction effort to date, and this VO2peak prediction equation provides clinicians who perform and interpret exercise tests in pediatric patients with a resource with which to better quantify fitness when CPET is not available.

Do Clinical Exercise Tests Permit Exercise Threshold Identification in Patients Referred to Cardiac Rehabilitation?

To evaluate the feasibility of "threshold-based" aerobic exercise prescription in cardiovascular disease, we aimed to quantify the proportion of patients whose clinical cardiopulmonary exercise test (CPET) permit identification of estimated lactate threshold (θLT) and respiratory compensation point (RCP) and to characterize the variability at which these thresholds occur. Breath-by-breath CPET data of 1102 patients (65 ± 12 years) referred to cardiac rehabilitation were analyzed to identify peak O2 uptake (V˙O2peak; mL·min-1 and mL·kg-1·min-1) and θLT and RCP (reported as V˙O2, %V˙O2peak, and %peak heart rate [%HRpeak]). Patients were grouped by the presence or absence of thresholds: group 0: neither θLT nor RCP; group 1: θLT only; and group 2: both θLT and RCP. Mean V˙O2peak was 1523 ± 627 mL·min-1 (range: 315-3789 mL·min-1) or 18.0 ± 6.5 mL·kg-1·min-1 (5.2-46.5 mL·kg-1·min-1) and HRpeak was 123 ± 24 beats per minute (bpm) (52 bpm-207 bpm). There were 556 patients (50%) in group 0, 196 (18%) in group 1, and 350 (32%) in group 2. In group 1, mean θLT was 1240 ± 410 mL·min-1 (580-2560 mL·min-1), 75% ± 8%V˙O2peak (52%-92%V˙O2peak), or 84%± 6%HRpeak (64%-96%HRpeak). In group 2, θLT was 1390 ± 360 mL·min-1 (640-2430 mL·min-1), 70% ± 8%V˙O2peak (41%-88%V˙O2peak), or 78% ± 7%HRpeak (52%-96%HRpeak), and RCP was 1680 ± 440 mL·min-1 (730-3090 mL·min-1), 84% ± 7%V˙O2peak (54%-99%V˙O2peak), or 87% ± 6%HRpeak (59%-99%HRpeak). Compared with group 1, θLT in group 2 occurred at a higher V˙O2 but lower %V˙O2peak and %HRpeak (P < 0.05). Only 32% of CPETs exhibited both θLT and RCP despite flexibility in protocol options. Commonly used step-based protocols are suboptimal for "threshold-based" exercise prescription.

Dynamic Ventilatory Reserve During Incremental Exercise: Reference Values and Clinical Validation in Chronic Obstructive Pulmonary Disease.

Rationale: Ventilatory demand-capacity imbalance, as inferred based on a low ventilatory reserve, is currently assessed only at peak cardiopulmonary exercise testing (CPET). Peak ventilatory reserve, however, is poorly sensitive to the submaximal, dynamic mechanical ventilatory abnormalities that are key to dyspnea genesis and exercise intolerance. Objectives: After establishing sex- and age-corrected norms for dynamic ventilatory reserve at progressively higher work rates, we compared peak and dynamic ventilatory reserve for their ability to expose increased exertional dyspnea and poor exercise tolerance in mild to very severe chronic obstructive pulmonary disease (COPD). Methods: We analyzed resting functional and incremental CPET data from 275 controls (130 men, aged 19-85 yr) and 359 Global Initiative for Chronic Obstructive Lung Disease patients with stage 1-4 obstruction (203 men) who were prospectively recruited for previous ethically approved studies in three research centers. In addition to peak and dynamic ventilatory reserve (1 - [ventilation / estimated maximal voluntary ventilation] × 100), operating lung volumes and dyspnea scores (0-10 on the Borg scale) were obtained. Results: Dynamic ventilatory reserve was asymmetrically distributed in controls; thus, we calculated its centile distribution at every 20 W. The lower limit of normal (lower than the fifth centile) was consistently lower in women and older subjects. Peak and dynamic ventilatory reserve disagreed significantly in indicating an abnormally low test result in patients: whereas approximately 50% of those with a normal peak ventilatory reserve showed a reduced dynamic ventilatory reserve, the opposite was found in approximately 15% (P < 0.001). Irrespective of peak ventilatory reserve and COPD severity, patients who had a dynamic ventilatory reserve below the lower limit of normal at an isowork rate of 40 W had greater ventilatory requirements, prompting earlier attainment of critically low inspiratory reserve. Consequently, they reported higher dyspnea scores, showing poorer exercise tolerance compared with those with preserved dynamic ventilatory reserve. Conversely, patients with preserved dynamic ventilatory reserve but reduced peak ventilatory reserve reported the lowest dyspnea scores, showing the best exercise tolerance. Conclusions: Reduced submaximal dynamic ventilatory reserve, even in the setting of preserved peak ventilatory reserve, is a powerful predictor of exertional dyspnea and exercise intolerance in COPD. This new parameter of ventilatory demand-capacity mismatch may enhance the yield of clinical CPET in the investigation of activity-related breathlessness in individual patients with COPD and other prevalent cardiopulmonary diseases.

Exercise Physiology and Cardiopulmonary Exercise Testing.

Aerobic, or endurance, exercise is an energy requiring process supported primarily by energy from oxidative adenosine triphosphate synthesis. The consumption of oxygen and production of carbon dioxide in muscle cells are dynamically linked to oxygen uptake (V̇O2) and carbon dioxide output (V̇CO2) at the lung by integrated functions of cardiovascular, pulmonary, hematologic, and neurohumoral systems. Maximum oxygen uptake (V̇O2max) is the standard expression of aerobic capacity and a predictor of outcomes in diverse populations. While commonly limited in young fit individuals by the capacity to deliver oxygen to exercising muscle, (V̇O2max) may become limited by impairment within any of the multiple systems supporting cellular or atmospheric gas exchange. In the range of available power outputs, endurance exercise can be partitioned into different intensity domains representing distinct metabolic profiles and tolerances for sustained activity. Estimates of both V̇O2max and the lactate threshold, which marks the upper limit of moderate-intensity exercise, can be determined from measures of gas exchange from respired breath during whole-body exercise. Cardiopulmonary exercise testing (CPET) includes measurement of V̇O2 and V̇CO2 along with heart rate and other variables reflecting cardiac and pulmonary responses to exercise. Clinical CPET is conducted for persons with known medical conditions to quantify impairment, contribute to prognostic assessments, and help discriminate among proximal causes of symptoms or limitations for an individual. CPET is also conducted in persons without known disease as part of the diagnostic evaluation of unexplained symptoms. Although CPET quantifies a limited sample of the complex functions and interactions underlying exercise performance, both its specific and global findings are uniquely valuable. Some specific findings can aid in individualized diagnosis and treatment decisions. At the same time, CPET provides a holistic summary of an individual's exercise function, including effects not only of the primary diagnosis, but also of secondary and coexisting conditions.

Reference Standards for Peak Rating of Perceived Exertion during Cardiopulmonary Exercise Testing: Data from FRIEND.

Peak rating of perceived exertion (RPE) is measured during clinical cardiopulmonary exercise testing (CPX) and is commonly used as a subjective indicator of maximal effort. However, no study to date has reported reference standards or the distribution of peak RPE across a large cohort of apparently healthy individuals. This study aimed to determine reference standards for peak RPE when using the 6-20 Borg scale for both treadmill and cycle tests. The analysis included 9551 tests (8821 treadmill, 730 cycle ergometer) from 13 laboratories within the Fitness Registry and Importance of Exercise National Database (FRIEND). Using data from tests conducted January 1, 1980, to January 1, 2021, percentiles of peak RPE for men and women were determined for each decade from 20 to 89 yr of age for treadmill and cycle exercise modes. Two-way ANOVA was used to compare differences in peak RPE values between sexes and across age groups. There were statistically significant differences in RPE between age groups whether the test was performed on a treadmill or cycle ergometer ( P < 0.05). However, the mean and median RPE for each sex, age group, and test mode were between 18 and 19. In addition, 83% of participants met the traditional RPE criteria of ≥18 for indicating sufficient maximal effort. This report provides the first normative reference standards for peak RPE in both male and female individuals performing CPX on a treadmill or cycle ergometer. Furthermore, these reference standards highlight the general consistency of peak RPE responses during CPX.

Abstract 9492: Ventricular Tachycardia During Cardiopulmonary Exercise Testing in Hypertrophic Cardiomyopathy

Introduction and Hypothesis: In patients with hypertrophic cardiomyopathy (HCM), ventricular tachycardia (VT) is associated with adverse prognosis. Cardiopulmonary exercise testing (CPET) is part of the standard clinical evaluation in HCM. However, limited data are available on the incidence of VT and other adverse events during CPET in HCM. Methods: We reviewed the Mayo Clinic’s Integrated Stress Center Database for CPETs performed on HCM patients between January 2011 and July 2016. Patients were referred for clinical CPET by a physician, and medications were continued for the test. Electronic medical records were reviewed for clinical information and CPET data. Results: A total of 1,208 CPETs were performed on 976 HCM patients during the study period. Most tests were symptom-limited (94.6%), most common symptom was dyspnea (55%). Despite the relatively high number of patients with a history of VT (10.4%) and/or cardiac arrest (1.6%), there was a low rate of adverse events. Non-sustained VT occurred in 6 patients, most frequently during active recovery (3/6), and 2 of these 6 patients had prior history of VT. A 34 year-old female patient experienced sustained VT degenerating into ventricular fibrillation terminated by ICD shock. One patient had syncope during the test but no arrhythmia. Importantly, none of the patients died within 48 hours of the exercise test. Conclusions: In a large cohort of HCM patients, the incidence of VT or other adverse events was a rare finding during symptom-limited CPET.

The impact of plasma 25-hydroxyvitamin D on pulmonary function and exercise physiology in cystic fibrosis: A multicentre retrospective study.

A 25-hydroxyvitamin D (25OHD) may exert immunomodulatory effects on respiratory health, which may translate to improvements in exercise physiology. Thus, we aimed to investigate whether plasma 25OHD is associated with lung function and aerobic fitness in people with cystic fibrosis (pwCF). A multicentre retrospective review of pwCF (>9years old) attending the Royal Hospital for Sick Children (Edinburgh) or Wessex CF-Unit (Southampton) was performed between July 2017 and October 2019. Demographic and clinical data were collected. Plasma 25OHD measured closest in time to clinical cardiopulmonary exercise testing and/or spirometry [forced expiratory volume (FEV1 )% predicted] was recorded. Pancreatic insufficiency was diagnosed based on faecal elastase of <100µg g-1 . We performed multiple-regression analysis with aerobic fitness outcomes [peak oxygen uptake (VO2peak )] and FEV1 % predicted as primary outcomes. Ninety pwCF [mean±SD age: 19.1±8.6years, 54 (60%) children, 48 (53%) males and 88 (98%) Caucasian] were included. 25OHD deficiency and insufficiency was 15 (17%) and 44 (49%), respectively. 25OHD deficiency and insufficiency was significantly associated with pancreatic insufficiency (χ2 =4.8, p=0.02). Plasma 25OHD was not significantly associated with FEV1 % predicted (r2 =0.06, p=0.42, 95% CI=-0.09 to 0.19) or VO2peak (r2 =0.04, p=0.07, 95% CI=-011 to 0.005) in all pwCF. However, 25OHD was significantly associated with both FEV1 % (r2 =0.15, p=0.02, 95% CI=1.99-2.64) and VO2peak (r2 =0.13, p=0.05, 95% CI=-0.26 to -0.005) in the paediatric cohort. We showed that 25OHD is associated with improved lung function and aerobic fitness in children and adolescents with CF. Mechanistic and high-quality prospective studies including both lung function and aerobic fitness as primary outcomes are now warranted.

Max test verify further clinical research for whether individualized symptom-limited cardiopulmonary exercise testing is the maximum extreme exercise

Objective: To verify that the cardiopulmonary exercise testing (CPET) performed by clinical subjects is the maximum extreme exercise, we designed The Max test（Max）during clinical CPET. We used Max to verify the accuracy of the quantitative CPET evaluation result, and whether it is feasible and safe to use the specific value of a certain index as the standard for stopping CPET. Methods: Two hundred and sixteen cases from Fuwai Hospital were selected during June 2017 to January 2019,including 41 healthy person（control group） and 175with cardiovascular diseases（patient group）,The patients had a CPET peak RER ≤ 1.10, or the peak heart rate and peak blood pressure were basically non-responsive.The Max was first attempted in 60 subjects,and this study is further expanded . When the CPET ended, they had a 5-minute break, then the Max, during which, they cycled with a velocity of ≥ 60 r/min, at a constant intensity equivalent to to 130% of peak work,until exhausted.The difference and percentage difference between the peak heart rate and the peak oxygen uptake were calculated. ①If the percentage difference of heart rate and oxygen uptake are all less than -10%,then the Max is defined as failure,otherwise it is succesful. 2 If the percentage difference is between -10%~10%, then the Max is successful, which proved that the CPET is precise.③If the difference is ≥10%, the Max is successful, which proves that the CPET is non-extreme exercise. Results: Patient group's Peak VO2(L/min,ml/(min·kg)),anaerobic threshold (L/min,ml/(min·kg),%pred),Peak VO2/HR(ml/beat, % pred),Peak RER,Peak SBP,Peak WR,peak heart rate,OUEP （ratio,%pred） were lower than those of the control group(P<0.05)．The VE/ VCO2 Slope （ratio,%pred）and Lowest VE/ VCO2（ratio,%pred） were higher in the patient group than in the control group (P<0.05)．No adverse events occurred during the CPET and Max in all cases. Among the 216 cases,Max was successful in 198 cases(91.7%)．CPET was proved to be maximum extreme exercise for 182 cases,non-maximum extreme exercise for 16 cases,and failed in 18 cases(8.3%)．Conclusion: For CPET with a low peak RER and a maximum challenge,the Max can confirm the accuracy of the objective quantitative assessment of CPET. Max is safe and feasible,and that deserved further research and clinical application.

Karlman Wasserman, MD, PHD, Physiologist and Physician-Scientist: 1927–2020

Karlman Wasserman, MD, PHD, Physiologist and Physician-Scientist: 1927–2020

Reference Values for Chronotropic Index from 1280 Incremental Cycle Ergometry Tests.

Clinical cardiopulmonary exercise testing can determine causes of exercise limitation. The slope of heart rate (fC) versus oxygen uptake (V˙O2), which we call the chronotropic index (CI), can help identify cardiovascular impairment. We aimed to develop a reference equation for CI based on a large number of subjects considered to have normal exercise responses. From a database of 13,728 incremental cycle ergometry exercise tests, we identified 1280 normal tests based on the absence of a clinical diagnosis, normal body mass index, and normal aerobic performance plus absence of cardiovascular disease, medications, or ventilatory limitation. A linear mixed-model approach was used to analyze the relationship between CI and other variables. Subjects were age 18-84 yr, and 693 (54.1%) were men. Mean ± SD CI in men was lower than in women, 41.2 ± 9.3 beats per liter versus 63.4 ± 15.7 L. Age (in years), sex (0, male; 1, female), height (in centimeters), and weight (in kilograms) were significant predictors for CI:CIi = 106.9 + 0.16 × agei + 14.3 × sexi - 0.31 × heighti - 0.24 × weighti. The SE of estimates ranged from 10.6 to 11.2 L (median of 10.7 L). We report a reference equation for CI derived from normal subjects. The CI can be used in conjunction with V˙O2max to interpret maximal cardiopulmonary exercise tests. We consider a high CI to be cardiovascular impairment and a low CI plus low V˙O2max to be chronotropic insufficiency.

Multidimensional aspects of dyspnea in obese patients referred for cardiopulmonary exercise testing

We investigated the contributions of obesity on multidimensional aspects of dyspnea on exertion (DOE) in patients referred for clinical cardiopulmonary exercise testing (CPET). Ratings of perceived breathlessness (RPB, Borg scale 0–10) were collected in obese (BMI ≥ 30; n = 47) and nonobese (BMI ≤ 25; n = 27) patients during two (one lower: ∼30 W; and one higher: ∼50 W) 4−6 min constant load cycling bouts. Multidimensional dyspnea profiles (MDP) were collected in the final 26 obese and 14 nonobese patients of the sample. RPB was greater (p = 0.05) in obese (3.3 ± 2.2 vs 2.4 ± 1.4) at lower work rates, but similar at higher work rates (4.9 ± 2.2 vs 4.4 ± 1.8). MDP sensory score including unpleasantness was 4.3 ± 2.2 in obese vs 2.5 ± 1.9 in nonobese (p < 0.001). The affective score was 1.9 ± 2.2 vs 0.7 ± 0.7, respectively (p < 0.01). Breathing sensations including ‘air hunger’, ‘effort’, and ‘breathing at lot’ were greater (p < 0.05) in obese, making these patients more frustrated/angry (p < 0.05). Obesity should be considered as a potential independent influencing factor that provokes DOE and unpleasantness when assessing breathlessness during CPET.

Integration of Brain Tissue Saturation Monitoring in Cardiopulmonary Exercise Testing in Patients with Heart Failure.

Cerebral hypo-oxygenation during rest or exercise negatively impacts the exercise capacity of patients with heart failure with reduced ejection fraction (HF). However, in clinical cardiopulmonary exercise testing (CPET), cerebral hemodynamics is not assessed. NIRS is used to measure cerebral tissue oxygen saturation (SctO2) in the frontal lobe. This method is reliable and valid and has been utilized in several studies. SctO2 is lower during both rest and peak exercise in patients with HF than in healthy controls (66.3 ± 13.3% and 63.4 ± 13.8% vs. 73.1 ± 2.8% and 72 ± 3.2%). SctO2 at rest is significantly linearly correlated with peak VO2 (r = 0.602), oxygen uptake efficiency slope (r = 0.501), and brain natriuretic peptide (r = -0.492), all of which are recognized prognostic and disease severity markers, indicating its potential prognostic value. SctO2 is determined mainly by end-tidal CO2 pressure, mean arterial pressure, and hemoglobin in the HF population. This article demonstrates a protocol that integrates SctO2 using NIRS into incremental CPET on a calibrated bicycle ergometer.

Exercise Stroke Volume in Adult Cystic Fibrosis: A Comparison of Acetylene Pulmonary Uptake and Oxygen Pulse.

Cardiac hemodynamic assessment during cardiopulmonary exercise testing (CPET) is proposed to play an important role in the clinical evaluation of individuals with cystic fibrosis (CF). Cardiac catheterization is not practical for routine clinical CPET. Use of oxygen pulse (O2pulse) as a noninvasive estimate of stroke volume (SV) has not been validated in CF. This study tested the hypothesis that peak exercise O2pulse is a valid estimate of SV in CF. Measurements of SV via the acetylene rebreathe technique were acquired at baseline and peak exercise in 17 mild-to-moderate severity adult CF and 25 age-matched healthy adults. We calculated . Baseline relationships between SV and O2pulse were significant in CF (r = .80) and controls (r = .40), persisting to peak exercise in CF (r = .63) and controls (r = .73). The standard error of estimate for O2pulse-predicted SV with respect to measured SV was similar at baseline (14.1 vs 20.1 mL) and peak exercise (18.2 vs 13.9 mL) for CF and controls, respectively. These data suggest that peak exercise O2pulse is a valid estimate of SV in CF. The ability to noninvasively estimate SV via O2pulse during routine clinical CPET can be used to improve test interpretation and advance our understanding of the impact cardiac dysfunction has on exercise intolerance in CF.

Perioperative cardiopulmonary exercise testing (CPET): consensus clinical guidelines on indications, organization, conduct, and physiological interpretation

The use of perioperative cardiopulmonary exercise testing (CPET) to evaluate the risk of adverse perioperative events and inform the perioperative management of patients undergoing surgery has increased over the last decade. CPET provides an objective assessment of exercise capacity preoperatively and identifies the causes of exercise limitation. This information may be used to assist clinicians and patients in decisions about the most appropriate surgical and non-surgical management during the perioperative period. Information gained from CPET can be used to estimate the likelihood of perioperative morbidity and mortality, to inform the processes of multidisciplinary collaborative decision making and consent, to triage patients for perioperative care (ward vs critical care), to direct preoperative interventions and optimization, to identify new comorbidities, to evaluate the effects of neoadjuvant cancer therapies, to guide prehabilitation and rehabilitation, and to guide intraoperative anaesthetic practice. With the rapid uptake of CPET, standardization is key to ensure valid, reproducible results that can inform clinical decision making. Recently, an international Perioperative Exercise Testing and Training Society has been established (POETTS www.poetts.co.uk) promoting the highest standards of care for patients undergoing exercise testing, training, or both in the perioperative setting. These clinical cardiopulmonary exercise testing guidelines have been developed by consensus by the Perioperative Exercise Testing and Training Society after systematic literature review. The guidelines have been endorsed by the Association of Respiratory Technology and Physiology (ARTP).

Use of 'ideal' alveolar air equations and corrected end-tidal PCO2 to estimate arterial PCO2 and physiological dead space during exercise in patients with heart failure.

Arterial CO2 tension (PaCO2) and physiological dead space (VD) are not routinely measured during clinical cardiopulmonary exercise testing (CPET). Abnormal changes in PaCO2 accompanied by increased VD directly contribute to impaired exercise ventilatory function in heart failure (HF). Because arterial catheterization is not standard practice during CPET, this study tested the construct validity of PaCO2 and VD prediction models using 'ideal' alveolar air equations and basic ventilation and gas-exchangegas exchange measurements during CPET in HF. Forty-seven NYHA class II/III HF (LVEF=21±7%; age=55±9years; male=89%; BMI=28±5kg/m2) performed step-wise cycle ergometry CPET to volitional fatigue. Breath-by-breath ventilation and gas exchange were measured continuously. Steady-state PaCO2 was measured at rest and peak exercise via radial arterial catheterization. Criterion VD was calculated via 'ideal' alveolar equations, whereas PaCO2 or VD models were based on end-tidal CO2 tension (PETCO2), tidal volume (VT), and/or weight. Criterion measurements of PaCO2 (38±5 vs. 33±5mmHg, P<0.01) and VD (0.26±0.07 vs. 0.41±0.15L, P<0.01) differed at rest vs. peak exercise, respectively. The equation, 5.5+0.90×PETCO2-0.0021×VT, was the strongest predictor of PaCO2 at rest and peak exercise (bias±95%LOA=-3.24±6.63 and -0.98±5.76mmHg; R2=0.57 and 0.75, P<0.001, respectively). This equation closely predicted VD at rest and peak exercise (bias±95%LOA=-0.03±0.06 and -0.02±0.13L; R2=0.86 and 0.83, P<0.001, respectively). These data suggest predicted PaCO2 and VD based on breath-by-breath gas exchange and ventilatory responses demonstrate acceptable agreement with criterion measurements at peak exercise in HF patients. Routine assessment of PaCO2 and VD can be used to improve interpretability of exercise ventilatory responses in HF.

Graphical Data Display for Clinical Cardiopulmonary Exercise Testing.

Cardiopulmonary exercise testing is a well-known, valuable tool in the clinical evaluation of patients with different causes of exercise limitation and unexplained dyspnea. A wealth of data is generated by each individual test. This may be challenging regarding a comprehensive and reliable interpretation of an exercise study in a timely manner. An optimized graphical display of exercise data may substantially help to improve the efficacy and reliability of the interpretation process. However, there are limited and heterogeneous recommendations on standardized graphical display in current exercise testing guidelines. To date, a widely used three-by-three array of specifically arranged graphical panels known as the "nine-panel plot" is probably the most common method of plotting exercise gas exchange data in a standardized way. Furthermore, optimized scaling of the plots, the use of colors and style elements, as well as suitable averaging methods have to be considered to achieve a high level of quality and reproducibility of the results. Specific plots of key parameters may allow a fast and reliable visual determination of important diagnostic and prognostic markers in cardiac and pulmonary diseases.

Dyspnea on Exertion in Nonobese and Obese Patients

PURPOSE: Dyspnea on exertion (DOE) is a common symptom in otherwise healthy obese individuals and in patients with serious illness. Whether obese patients have an exaggerated rating of breathlessness (RPB) as compared with nonobese patients is unknown. In a retrospective analysis, we investigated RPB in nonobese and obese patients who were referred for clinical cardiopulmonary exercise testing (CPET) due to unexplained DOE. METHODS: Data from 112 patients were separated into nonobese (BMI < 30; n = 28; 20 F) and obese (BMI ≥ 30; n = 47; 24 F) groups. All patients cycled at two individualized constant load work rates (one easy & one harder) for 4-6 mins, followed by a peak exercise test. Constant load work rates were set based on the patient’s symptoms and physical activity habits. During the last minute of each constant load exercise bout, patients’ RPBs were obtained (Borg scale 0-10). Groups were compared by independent t test and relationships between variables were examined by regression analysis. RESULTS: BMI was 22 ± 2 kg/m2 in the nonobese (62 ± 9 kg) and 36 ± 4 kg/m2 in the obese (103 ± 16 kg) patients (mean ± SD; p < 0.001). Age was not different between groups (50 ± 20 yr vs 57 ± 12 yr). Work rates were not significantly different between the nonobese and obese patients at the lower (29 ± 19 W vs 24 ± 14 W) or higher constant load work rates (59 ± 35 W vs 49 ± 27 W). Exercise intensity was also not different between groups at the lower (53 ± 11 vs 56 ± 13% of peak O2 uptake) or higher work rates (74 ± 11 vs 72 ± 11%). RPB was significantly (p = 0.05) greater in the obese patients (2.3 ± 1.4 vs 3.3 ± 2.2) at the lower work rate, but not at the higher work rate (4.4 ± 1.8 vs 4.9 ± 2.2). Maximal exercise capacity was higher in the nonobese patients (77 ± 24 vs 58 ± 21% predicted). There was no significant relationship between RPB and BMI within either group. However, there was a significant (p < 0.001) association between RPB and ratings of perceived exertion (RPE) in the nonobese (r = 0.68 & 0.82 for lower & higher constant work rates) and the obese (r = 0.87 & 0.81) patients. CONCLUSIONS: Obesity appears to have a significant effect on breathlessness at lower work rates in this mixed patient population, and should be considered when assessing breathlessness in patients. Supported by NIH R01 HL096782, King Charitable Foundation Trust, and Texas Health Presbyterian Hospital Dallas

The Use of Prediction Equations in Hypertrophic Cardiomyopathy

PURPOSE: To evaluate a recent equation (FRIEND) for the estimation of peak exercise capacity (VO2peak) in a heterogeneous clinical population of patients with cardiomyopathy against the current standard in estimation equations (Wasserman, 1986). METHODS: 1100 consecutive ambulatory patients performed clinical cardiopulmonary exercise testing (CPX) at Stanford University. VO2peak was measured directly during CPX (CosMed USA), and estimated VO2peak were calculated using the FRIEND (Fitness Registry and the Importance of Exercise: National Database) registry equation and the equation from Wasserman et al. VO2peak data were assessed for variation around the median and comparisons were made. RESULTS: Patients were on average 48 (15) y and 62% male. VO2peak as measured by CPX was on average 23.7 (9.8) ml/kg/min. The Wasserman equation average prediction for VO2peak was 27.8 (9.4) which resulted in an percent predicted of 88%, whereas the FRIEND equation resulted in average predicted VO2peak of 42.2 (10.3) ml/kg/min, resulting in 56% of predicted. CONCLUSIONS: In a large sample of patients with known moderate to severe cardiomyopathy, the standard reference equation by Wasserman assessed them as slightly below average whereas the FRIEND equation assessed the same patients as having severely impaired performance. Caution should be used in the interpretation of CPX results when using current VO2peak estimation equations and further development of these equations seems warranted.