Cardiopulmonary Exercise Testing (cardiopulmonary + exercise_testing)

Distribution by Scientific Domains


Selected Abstracts


Design and validation of an interpretative strategy for cardiopulmonary exercise tests

RESPIROLOGY, Issue 6 2007
Andreas SCHMID
Background and objective: Cardiopulmonary exercise testing (CPET) is a common investigation for the evaluation of exertional dyspnoea. At present, there is no consensus on the best interpretative strategy and none of the available algorithms have been validated. The aim of this study was to develop and validate a standardized strategy for the interpretation of CPET. Methods: This study analysed 199 CPETs from patients with exertional dyspnoea. Using a set of 100 CPETs a standardized interpretation using a four-step approach was developed that scored: examination quality, performance, exercise limitation and cofactors. A second set of 99 CPETs was interpreted by two experts in the field, initially independently and then in a consensus conference. The standardized interpretation was compared with each expert, the expert's consensus and the original clinical reports. Results: Matching between the standardized interpretation strategy and the expert consensus was 82%, 82% with one expert and 86% with a second expert and 64% with the original clinical reports. From one to four exercise-relevant cofactors were found in 77% of the patients. Conclusion: The standardized interpretation showed a precision comparable to the opinion of a single expert and significantly improved the consistency in CPET reports in a pulmonary centre with different physicians and varying degrees of expertise. [source]


Cardiopulmonary exercise testing: the physiological basis

ANAESTHESIA, Issue 3 2010
B. Phypers
No abstract is available for this article. [source]


Cardiopulmonary exercise testing in endovascular repair of abdominal aortic aneurysm

ANAESTHESIA, Issue 2 2010
P. S. Lancaster
No abstract is available for this article. [source]


Cardiopulmonary exercise testing as a risk assessment method in non cardio-pulmonary surgery: a systematic review

ANAESTHESIA, Issue 8 2009
T. B. Smith
Summary This study reviews the predictive value of maximum oxygen consumption () and anaerobic threshold, obtained through cardiopulmonary exercise testing, in calculating peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. A literature review provided nine studies that investigated either one or both of these two variables across a wide range of surgical procedures. Six of the seven studies that reported sufficiently detailed results on peak oxygen consumption and four of the six studies that reported sufficiently detailed results on anaerobic threshold found them to be significant predictors. We conclude that peak oxygen consumption and possibly anaerobic threshold are valid predictors of peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. These indicators could potentially provide a means of allocating increased care to high-risk patients. [source]


The Role of Natriuretic Peptides in Patients With Chronic Complex (Mixed or Multiple) Heart Valve Disease

CONGESTIVE HEART FAILURE, Issue 2 2010
FRACP, Naylin Bissessor MBChB
N-terminal prohormone B-type natriuretic peptide (NT-proBNP) is an important biomarker of prognosis in heart failure and single valve disease. There are limited studies of complex valve disease. Patients with complex valve disease adopt a sedentary lifestyle, so symptoms may be difficult to detect. The authors aimed to determine whether NT-proBNP correlates with the severity of the valve lesion and underlying cardiac function and whether resting NT-proBNP predicts impaired peak VO2 in patients with complex valve disease. Forty-five patients with complex moderate to severe stenosis or regurgitation of the heart valves underwent a clinical assessment, echocardiography, resting NT-proBNP assessment, and formal cardiopulmonary exercise testing. In a multivariate analysis, the log NT-proBNP (,=,9.3, SE=1.9, P<.0001) and lean body weight (,=0.59, SE=0.22, P=.01) were dominant independent predictors of peak VO2. An NT-proBNP value of 84 pmol/L had 77% sensitivity and 70% specificity to predict impaired functional capacity, peak VO2 <60% (predicted), area under the curve=0.80. Resting NT-proBNP was the best predictor of peak VO2 in patients with complex valve disease, while symptoms and ejection fraction are a less reliable guide. Congest Heart Fail. 2010;16:50,54. © 2009 Wiley Periodicals, Inc. [source]


Impaired oxygen kinetics in beta-thalassaemia major patients

ACTA PHYSIOLOGICA, Issue 3 2009
I. Vasileiadis
Abstract Aim:, Beta-thalassaemia major (TM) affects oxygen flow and utilization and reduces patients' exercise capacity. The aim of this study was to assess phase I and phase II oxygen kinetics during submaximal exercise test in thalassaemics and make possible considerations about the pathophysiology of the energy-producing mechanisms and their expected exercise limitation. Methods:, Twelve TM patients with no clinical evidence of cardiac or respiratory disease and 10 healthy subjects performed incremental, symptom-limited cardiopulmonary exercise testing (CPET) and submaximal, constant workload CPET. Oxygen uptake (Vo2), carbon dioxide output and ventilation were measured breath-by-breath. Results:, Peak Vo2 was reduced in TM patients (22.3 ± 7.4 vs. 28.8 ± 4.8 mL kg,1 min,1, P < 0.05) as was anaerobic threshold (13.1 ± 2.7 vs. 17.4 ± 2.6 mL kg,1 min,1, P = 0.002). There was no difference in oxygen cost of work at peak exercise (11.7 ± 1.9 vs. 12.6 ± 1.9 mL min,1 W,1 for patients and controls respectively, P = ns). Phase I duration was similar in TM patients and controls (24.6 ± 7.3 vs. 23.3 ± 6.6 s respectively, P = ns) whereas phase II time constant in patients was significantly prolonged (42.8 ± 12.0 vs. 32.0 ± 9.8 s, P < 0.05). Conclusion:, TM patients present prolonged phase II on-transient oxygen kinetics during submaximal, constant workload exercise, compared with healthy controls, possibly suggesting a slower rate of high energy phosphate production and utilization and reduced oxidative capacity of myocytes; the latter could also account for their significantly limited exercise tolerance. [source]


Maximum Daily 6 Minutes of Activity: An Index of Functional Capacity Derived from Actigraphy and Its Application to Older Adults with Heart Failure

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 5 2010
Jason Howell BA
OBJECTIVES: To compare the correlation between the maximum 6 minutes of daily activity (M6min) and standard measures of functional capacity in older adults with heart failure (HF) with that in younger subjects and its prognostic utility. DESIGN: Prospective, cohort study. SETTING: Tertiary care, academic HF center. PARTICIPANTS: Sixty, ambulatory, adults, New York Heart Association (NYHA) Class I to III, stratified into young (50.9 ± 9.4) and older cohorts (76.8 ± 8.0). MEASUREMENTS: Correlation between M6min and measures of functional capacity (6-minute walk test; 6MWT) and peak oxygen consumption (VO2) according to cardiopulmonary exercise testing in a subset of subjects. Survival analysis was employed to evaluate the association between M6min and adverse events. RESULTS: Adherence to actigraphy was high (90%) and did not differ according to age. The correlation between M6min and 6MWT was higher in subjects aged 65 and older than in those younger than 65 (correlation coefficient (r=0.702, P<.001 vs r=0.490, P=.002). M6min was also significantly associated with peak VO2 (r=0.612, P=.006). During the study, 26 events occurred (2 deaths, 10 hospitalizations, 8 emergency department visits, and 6 intercurrent illnesses). The M6min was significantly associated with subsequent events (hazard ratio=2.728, 95% confidence interval=1.10,6.77, P=.03), independent of age, sex, ejection fraction, NYHA class, brain natriuretic peptide, and 6MWT. CONCLUSION: The high adherence to actigraphy and association with standard measures of functional capacity and independent association with subsequent morbid events suggest that it may be useful for monitoring older adults with HF. [source]


Utilization of Defibrillators and Resynchronization Therapy at the Time of Evaluation at a Heart Failure and Cardiac Transplantation Center

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010
DANIEL B. SIMS M.D.
Background: Internal cardioverter defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce mortality, but are underutilized in routine clinical practice. The use of these devices in patients at the time of an initial evaluation at an advanced heart failure and cardiac transplantation center is unknown. Methods: We retrospectively analyzed consecutive patients who were enrolled in a database examining parameters of cardiopulmonary exercise testing in chronic heart failure (CHF) patients at the time of an initial outpatient evaluation at a tertiary care center. Rates of ICD and CRT use in eligible patients were determined. Results: Two hundred two patients had an average age of 54 ± 13 years and an average peak oxygen consumption (pVO2) of 12.5 ± 4.5 mL/kg/min. Of 97 patients eligible for an ICD only, 57% had an ICD at the time of evaluation. Sixty-four percent of ICD-eligible male patients had an ICD compared to 36% of ICD-eligible female patients (P = 0.015). Of 105 patients meeting criteria for CRT, 54% had a CRT device. There was no difference between CRT use in eligible male and female patients. Conclusions: ICDs and CRT are underutilized in patients with severe CHF at the time of evaluation at a tertiary care center despite young age, objective functional limitation, and active consideration for advanced CHF therapies. Female patients have lower rates of ICD use than male patients. (PACE 2010; 988,993) [source]


Impact of Right Ventricular Pacing Sites on Exercise Capacity during Ventricular Rate Regularization in Patients with Permanent Atrial Fibrillation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2009
HUNG-FAT TSE M.D., Ph.D.
Background:The deleterious effects of right ventricular apical (RVA) pacing may offset the potential benefit of ventricular rate (VR) regularization and rate adaptation during an exercise in patient's atrial fibrillation (AF). Methods:We studied 30 patients with permanent AF and symptomatic bradycardia who receive pacemaker implantation with RVA (n = 15) or right ventricular septal (RVS, n = 15) pacing. All the patients underwent an acute cardiopulmonary exercise testing using VVI-mode (VVI-OFF) and VVI-mode with VR regularization (VRR) algorithm on (VVI-ON). Results:There were no significant differences in the baseline characteristics between the two groups, except pacing QRS duration was significantly shorter during RVS pacing than RVA pacing (138.9 ± 5 vs 158.4 ± 6.1 ms, P = 0.035). Overall, VVI-ON mode increased the peak exercise VR, exercise time, metabolic equivalents (METs), and peak oxygen consumption (VO2max), and decreased the VR variability compared with VVI-OFF mode during exercise (P < 0.05), suggesting that VRR pacing improved exercise capacity during exercise. However, further analysis on the impact of VRR pacing with different pacing sites revealed that only patients with RVS pacing but not patients with RVA pacing had significant increased exercise time, METs, and VO2max during VVI-ON compared with VVI-OFF, despite similar changes in peaked exercise VR and VR variability. Conclusion:In patients with permanent AF, VRR pacing at RVS, but not at RVA, improved exercise capacity during exercise. [source]


AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double-blind, Crossover Trial

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2001
BERNHARD SCHWAAB
SCHWABB, B., et al.: AAIR Versus DDDR Pacing in the Bradycardia Tachycardia Syndrome: A Prospective, Randomized, Double-blind, Crossover Trial. In 19 patients paced and medicated for bradycardia tachycardia syndrome (BTS), AAIR and DDDR pacing were compared with regard to quality of life (QoL), atrial tachyarrhythmia (AFib), exercise tolerance, and left ventricular (LV) function. Patients had a PQ interval , 240 ms during sinus rhythm, no second or third degree AV block, no bundle branch block, or bifascicular block. In DDDR mode, AV delay was optimized using the aortic time velocity integral. After 3 months, QoL was assessed by questionnaires, patients were investigated by 24-hour Holter, cardiopulmonary exercise testing (CPX) was performed, and LV function was determined by echocardiography. QoL was similar in all dimensions, except dizziness, showing a significantly lower prevalence in AAIR mode. The incidence of AFib was 12 episodes in 2 patients with AAIR versus 22 episodes in 7 patients with DDDR pacing (P = 0.072). In AAIR mode, 164 events of second and third degree AV block were detected in 7 patients (37%) with pauses between 1 and 4 seconds. During CPX, exercise duration and work load were higher in AAIR than in DDDR mode (423 ± 127 vs 402 ± 102 s and 103 ± 31 vs 96 ± 27 Watt, P < 0.05). Oxygen consumption (VO2), was similar in both modes. During echocardiography, only deceleration of early diastolic flow velocity and early diastolic closure rate of the anterior mitral valve leaflet were higher in DDD than in AAI pacing (5.16 ± 1.35 vs 3.56 ± 0.95 m/s2 and 69.2 ± 23 vs 54.1 ± 26 mm/s, P < 0.05). As preferred pacing mode, 11 patients chose DDDR, 8 patients chose AAIR. Hence, AAIR and DDDR pacing seem to be equally effective in BTS patients. In view of a considerable rate of high degree AV block during AAIR pacing, DDDR mode should be preferred for safety reasons. [source]


Functional capacity in children and young adults with sickle cell disease undergoing evaluation for cardiopulmonary disease,

AMERICAN JOURNAL OF HEMATOLOGY, Issue 10 2009
Robert I. Liem
Although cardiopulmonary disease is associated with decreased functional capacity among adults with sickle cell disease (SCD), its impact on functional capacity in children with SCD is unknown. We evaluated 6-min walk (6MW) distance in 77 children and young adults with SCD undergoing screening for cardiopulmonary disease. Of 30 subjects who also underwent cardiopulmonary exercise testing, we found evidence for decreased exercise capacity in a significant proportion. Exercise capacity was related to baseline degree of anemia and was significantly lower in subjects with a history of recurrent acute chest syndrome. We found that 6MW distance adjusted for weight and body surface area was shorter in subjects with restrictive lung disease but that only 6MW adjusted for weight remained significantly shorter when we controlled for baseline hemoglobin. Exercise capacity was not significantly different in subjects with and without cardiopulmonary disease. We conclude that restrictive lung disease is associated with shorter 6MW distances in children and young adults with SCD, but that variables associated with decreased exercise capacity, other than anemia, remain unclear. Our study underscores the importance of further delineating the direct pathophysiologic processes that contribute to decreased exercise capacity observed among individuals with SCD and cardiopulmonary disease. Am. J. Hematol., 2009. © 2009 Wiley-Liss, Inc. [source]


Interobserver variability in determination of anaerobic threshold by cardiopulmonary exercise testing

ANAESTHESIA, Issue 1 2010
K. Patrick
No abstract is available for this article. [source]


Cardiopulmonary exercise testing as a risk assessment method in non cardio-pulmonary surgery: a systematic review

ANAESTHESIA, Issue 8 2009
T. B. Smith
Summary This study reviews the predictive value of maximum oxygen consumption () and anaerobic threshold, obtained through cardiopulmonary exercise testing, in calculating peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. A literature review provided nine studies that investigated either one or both of these two variables across a wide range of surgical procedures. Six of the seven studies that reported sufficiently detailed results on peak oxygen consumption and four of the six studies that reported sufficiently detailed results on anaerobic threshold found them to be significant predictors. We conclude that peak oxygen consumption and possibly anaerobic threshold are valid predictors of peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. These indicators could potentially provide a means of allocating increased care to high-risk patients. [source]


Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms,

ANAESTHESIA, Issue 1 2009
E. Kothmann
Summary Anaerobic threshold (AT), determined by cardiopulmonary exercise testing (CPET), is a well-documented measure of pre-operative fitness, although its reliability in patient populations is uncertain. Our aim was to assess the reliability of AT measurement in patients with abdominal aortic aneurysms. Eighteen patients were recruited. CPET was performed four times over a 6-week period. We examined shifts in the mean AT to evaluate systematic bias with random measurement error assessed using typical within-patient error and intraclass correlation coefficient (ICC, 3,1) statistics. There was no significant or clinically substantial change in mean AT across the tests (p = 0.68). The typical within-patient error expressed as a percentage coefficient of variation was 10% (95% CI, 8,13%), with an ICC of 0.74 (95% CI, 0.55,0.89). We consider the reliability of the AT to be acceptable, supporting its clinical validity and utility as an objective marker of pre-operative fitness in this population. [source]


ST Segment "Hump" during Exercise Testing and the Risk of Sudden Cardiac Death in Patients with Hypertrophic Cardiomyopathy

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2009
Andreas P. Michaelides M.D., F.A.C.C., F.E.S.C.
Background: The appearance of a discrete upward deflection of the ST segment termed "the ST hump sign" (STHS) during exercise testing has been associated with resting hypertension and exaggerated blood pressure response to exercise. Objective: We investigated the prevalence and clinical significance of this sign in a population of patients with hypertrophic cardiomyopathy. Methods: Eighty-one patients with hypertrophic cardiomyopathy (HCM) who underwent cardiopulmonary exercise testing were followed in a retrospective cohort study for a mean period of 5.3 years. Results: The appearance of the STHS at the peak of exercise testing was observed in 42 patients (52%), particularly in the inferior and the lateral leads. Patients with the STHS had higher fractional shortening and maximum left ventricular wall thickness and exhibited more frequently outflow tract gradient >30 mmHg at rest. Furthermore, the presence of STHS was a strong independent predictor of the risk of sudden cardiac death (SCD), as the latter occurred in eight of the patients with this sign (8/42, 19%) and in none of the patients without it (0/39, 0%) (P < 0.001). Conclusion: The appearance of a "hump" at the ST segment during exercise testing appears to be a risk factor for SCD in patients with HCM. However, further studies are necessary to validate this finding in larger populations and to elucidate the mechanism of the appearance of the "hump." [source]


Mid-term survival after abdominal aortic aneurysm surgery predicted by cardiopulmonary exercise testing

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2007
J. Carlisle
Background: Cardiopulmonary exercise (CPX) testing measures how efficiently subjects meet increased metabolic demand. This study aimed to determine whether preoperative CPX testing predicted postoperative survival following elective abdominal aortic aneurysm (AAA) repair. Methods: Some 130 patients had CPX testing before elective open AAA repair. Additional preoperative, operative and postoperative variables were recorded prospectively. Median follow-up was 35 months. The correlation of variables with survival was assessed by single and multiple regression analyses. Results: CPX testing identified 30 of 130 patients who had been unfit before surgery. Two years after surgery the Kaplan,Meier survival estimate was 55 per cent for the 30 unfit patients, compared with 97 per cent for the 100 fit patients. The absolute difference in survival between these two groups at 2 years was 42 (95 per cent confidence interval 18 to 65) per cent (P < 0·001). Conclusion: Preoperative CPX testing, combined with simple co-morbidity scoring, identified patients unlikely to survive in the mid-term, even after successful AAA repair. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source]


Measurement of physical work capacity in patients with chronic aortic regurgitation: a potential improvement in patient management

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2009
Éva Tamás
Summary Background:, Timing of surgery in aortic regurgitation (AR) is important. Exercise testing is recommended upon uncertainty about functional limitations but reports on cardiopulmonary exercise testing (CPET) in populations with pure chronic AR are scarce. Method:, Twenty-eight patients referred for surgery because of chronic AR (13 in NYHA I, 10 in NYHA II and five in NYHA III) were tested by CPET pre- and 6 months postoperatively. Echocardiography, with measurement of left ventricular ejection fraction (LVEF), diameters (LVED, LVES) and volumes (LVEDV, LVESV) was also performed. Results:, The patients had normal LVEF pre- and postoperatively. LV diameters and volumes diminished significantly postoperatively (LVED from 67 to 57, LVES from 49 to 41 mm; P < 0·001). The majority of the patients had a ,low' physical work capacity, none of them performed better than ,average' according to Ĺstrand's classification preoperatively and there was no significant postoperative improvement. The mean peak oxygen uptake () was 25 ml kg,1 min,1 both pre- and postoperatively, and six of the 28 patients had a of less than 20 ml kg,1 min,1. was not significantly related to NYHA class. Conclusion:, LVEF, diameters and volumes at rest did not fulfil the criteria for surgery in most of our AR patients, of whom 46% were asymptomatic. However, many had a remarkably low work capacity, which was neither improved 6 months postoperatively nor correlated to echocardiographic LV dimensions. CPET predicted the postoperative work capacity and may, therefore, be a useful complement for timing of surgery in patients with chronic AR. [source]


Scaling of lactate threshold by peak oxygen uptake and by fat-free mass0·67

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 3 2007
James A. Davis
Summary The lactate threshold (LT) represents the onset of metabolic acidosis during cardiopulmonary exercise testing (CPET). It is measured as a O2 in the units of ml min,1. In order to make comparisons among subjects, LT is often scaled or normalized by O2 peak resulting in the LT/O2 peak ratio. Ratio variables have underlying assumptions. One assumption is that the relationship between the numerator and denominator is linear with a zero y -intercept. If the relationship has a positive y -intercept, then the ratio will decrease with increasing values of the scaling variable thereby penalizing subjects with larger values of the scaling variable. Our purpose was to examine the validity of scaling LT by O2 peak and by fat-free mass raised to 0·67 power (FFM0·67) as dimensional analysis predicts that LT is proportional to FFM0·67. Cycle ergometer CPET was administered to 204 healthy, sedentary subjects (103 males) to the limit of tolerance. Lactate threshold was estimated noninvasively using the V-slope technique. Fat-free mass was assessed by skinfolds. The relationship of LT versus O2 peak was linear with a positive y -intercept for both sexes. Consequently, the LT/O2 peak ratio decreased as O2 peak increased for both sexes. The relationship of LT versus FFM0·67was linear with a zero y -intercept for both sexes. Consequently, the plot of the LT/FFM0·67 ratio versus FFM resulted in a straight line with a slope of zero for both sexes. The results of this study support the conclusion that FFM0·67, but not O2 peak, is a valid scaling variable for LT. [source]


Is ventilatory efficiency dependent on the speed of the exercise test protocol in healthy men and women?

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 2 2006
James A. Davis
Summary Indices of ventilatory efficiency have proven useful in assessing patients with heart and lung disease. One of these indices is the slope of the ventilation (V,E) versus carbon dioxide output (V,CO2) relationship during cardiopulmonary exercise testing (CPET) for work rates where the relationship is linear. However, this relationship is defined not only by the slope but also by the y -intercept. To examine whether this relationship is dependent on the speed of the CPET protocol, 30 healthy subjects (16 males) were administered a rapid CPET with 1-min increment duration (1-min CPET) to the limit of tolerance and a slow CPET with 4-min increment duration (4-min CPET) to the lactate threshold. Ventilation and the gas fractions for oxygen and CO2 were measured with a Vacumed metabolic cart. The average increment size of both protocols for both sexes was not significantly different (P>0·05). For the males, the mean (SD) slope for the 1- and 4-min CPET was 20·12 (2·61) and 20·37 (2·41), respectively. The corresponding values for the y -intercept were 4.·89 (2·08) and 5.·10 (2·00) l min,1. For the females, the mean (SD) slope for the 1- and 4-min CPET was 23·90 (2·38) and 24·16 (2·55), respectively. The corresponding values for the y -intercept were 3·93 (0·39) and 3·77 (0·71) l min,1. Paired t -test analysis demonstrated for both sexes that the slopes and y -intercepts were not different for the two protocols (P>0·05). The results of this study demonstrate that the V,E versus V,CO2 relationship is not dependent on the speed of the CPET protocol. [source]


Exercise test mode dependency for ventilatory efficiency in women but not men

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 2 2006
James A. Davis
Summary Ventilatory efficiency is commonly defined as the level of ventilation V,E at a given carbon dioxide output (V,CO2). The slope of the V,E versus V,CO2 relationship and the lowest V,E/V,CO2 are two ventilatory efficiency indices that can be measured during cardiopulmonary exercise testing (CPET). A possible CPET mode dependency for these indices was evaluated in healthy men and women. Also evaluated was the relationship between these two indices as, in theory, V,E/V,CO2 falls hyperbolically towards an asymptote that numerically equals the V,E versus V,CO2 slope at exercise levels below the ones that cause respiratory compensation for metabolic acidosis. Twenty-eight healthy subjects (14 men) underwent treadmill and cycle ergometer CPET on different days. Ventilation and the gas fractions for oxygen and CO2 were measured with a vacumed metabolic cart. In men, paired t -test analysis failed to find a mode difference for either ventilatory efficiency index but the opposite was true in the women as each woman had higher values for both indices on the treadmill. For men, the lowest V,E/V,CO2 was larger than the V,E versus V,CO2 slope by 1·3 on the treadmill and 0·8 on the cycle ergometer. The corresponding values for women were 1·7 and 1·4. We conclude that in healthy subjects, women, but not men, demonstrate a mode dependency for the two ventilatory efficiency indices investigated in this study. Furthermore, our results are consistent with the theoretical expectation that the lowest V,E/V,CO2 has a numerical value just above the asymptote of the V,E/V,CO2 versus V,CO2 relationship. [source]