Peak VO2 In Patients Research Articles

The 2016 International Society for Heart Lung Transplantation listing criteria for heart transplantation: A 10-year update

Mandeep R. Mehra, MD (Chair), Charles E. Canter, MD, Margaret M. Hannan, MD, Marc J. Semigran, MD, Patricia A. Uber, PharmD, David A. Baran, MD, Lara Danziger-Isakov, MD, MPH, James K. Kirklin, MD, Richard Kirk, MD, Sudhir S. Kushwaha, MD, Lars H. Lund, MD, PhD, Luciano Potena, MD, PhD, Heather J. Ross, MD, David O. Taylor, MD, Erik A.M. Verschuuren, MD, PhD, Andreas Zuckermann, MD and on behalf of the International Society for Heart Lung Transplantation (ISHLT) Infectious Diseases, Pediatric and Heart Failure and Transplantation Councils

Daily life activity in patients with left ventricular assist devices.

Exercise capacity is usually evaluated by peak oxygen consumption (peak-VO2). However, assessment of peak-VO2 in patients with a left ventricular assist device (LVAD) might not be the best method to provide insight into their daily life activity. The aim of this study was to assess the postoperative activity of LVAD patients using actigraphy and to compare these patients to a healthy and a heart-transplanted (HTx) population. Activity was continuously monitored using wrist-accelerometers in LVAD patients after implantation, during 4 weeks of rehabilitation following hospital discharge, and at 2 follow-up assessments. Peak-VO2 values measured during rehabilitation were correlated with activity. Additionally, actigraphy data from LVAD recipients were compared with data measured in healthy and HTx subjects. After hospital discharge a significant increase in physical activity of LVAD recipients was observed (55 ± 28 vs. 102 ± 23 Activity Scores, n = 11, p = 0.002). During rehabilitation as well as at the follow-ups (140 ± 43 and 253 ± 33 days post-implantation) no significant increase in activity was observed. Peak-VO2 values correlated to daily activity both in LVAD and HTx patients (r > 0.5). Average daily activity was significantly lower in LVAD and HTx patients than in the healthy population (130 ± 30 and 148 ± 60 vs. 245 ± 63 Activity Score; n = 18 in each group, p < 0.001). Activity in LVAD recipients increased substantially after hospital discharge with no further significant improvement observed during a period of 8.5 months. Similarly to the peak-VO2, also the daily activity of LVAD recipients was 53% compared to healthy subjects. These results highlight the need for an optimized physical therapy in this patient cohort.

Association between baseline cardiovascular mechanics and exercise capacity in patients with coronary artery disease.

Objective:Functional capacity is one of the cardinal determinants of morbidity and mortality in patients with coronary artery disease (CAD). We hypothesized that baseline cardiovascular mechanics, including cardiac systolic and diastolic functions, arterial mechanics, and ventriculo-arterial interaction, may play a role in predicting exercise capacity in patients with CAD.Methods:Fifty consecutive patients with CAD who were referred to cardiac rehabilitation were prospectively included in the study. Patients with non-sinus rhythms or severe valvular disease were excluded. Full left ventricular pressure–volume loops were constructed and arterial mechanics was evaluated using echocardiographic and tonometric measurements. Cardiopulmonary exercise tests were performed to measure exercise capacity.Results:Fifty patients were enrolled in the study. Ventriculo-arterial coupling showed a moderate correlation with peak oxygen consumption (VO2) (r=0.410, p=0.04) in patients with reduced left ventricular ejection fraction (LVEF). Only left ventricular volume at 15 mm Hg (r=0.514, p<0.01) in diastolic parameters (stiffness constant, p=0.75; ventricular compliance, p=0.17) and arterial compliance (r=0.467, p=0.01) in arterial parameters [arterial elastance, p=0.27; systemic vascular resistance, p=0.45; augmentation pressure, p=0.85; augmentation index (AIx), p=0.63; heart rate-corrected AIx, p=0.68] emerged as significant factors correlated with peak VO2 in patients with normal LVEF.Conclusion:Comprehensive evaluation of resting cardiovascular mechanics can give clues about exercise-recruited reserves of the cardiovascular system. Optimization of ventriculo-arterial coupling in patients with reduced LVEF and arterial compliance in patients with normal LVEF should be the main target in patients with CAD and limited functional capacity. (Anatol J Cardiol 2016; 16: 608-14)

High Intensity Interval versus Moderate Intensity Continuous Training in Patients with Coronary Artery Disease: A Meta-analysis of Physiological and Clinical Parameters

Exercise-based cardiac rehabilitation for patients with coronary artery disease (CAD) significantly improves their outcome, although the optimal mode of exercise training remains undetermined. Previous analyses have been constrained by small sample sizes and a limited focus on clinical parameters. Further, results from previous studies have been contradicted by a recently published large RCT. We performed a meta-analysis of published randomised controlled trials to compare high intensity interval training (HIIT) and moderate intensity continuous training (MCT) in their ability to improve patients' aerobic exercise capacity (VO2peak) and various cardiovascular risk factors. We included patients with established coronary artery disease without or without impaired ejection fraction. Ten studies with 472 patients were included for analyses (218 HIIT, 254 MCT). Overall, HIIT was associated with a more pronounced incremental gain in participants' mean VO2peak when compared with MCT (+1.78mL/kg/min, 95% CI: 0.45-3.11). Moderate intensity continuous training however was associated with a more marked decline in patients' mean resting heart rate (-1.8/min, 95% CI: 0.71-2.89) and body weight (-0.48kg, 95% CI: 0.15-0.81). No significant differences were noted in the level of glucose, triglyceride and HDL at the end of exercise program between the two groups. High intensity interval training improves the mean VO2peak in patients with CAD more than MCT, although MCT was associated with a more pronounced numerical decline in patients' resting heart rate and body weight. The underlying mechanisms and clinical relevance of these results are uncertain, and remain a potential focus for future studies.

Tai Chi Chuan improves functional capacity after myocardial infarction: A randomized clinical trial

Patients with a recent myocardial infarction (MI) present a reduction in functional capacity expressed as a decrease in peak oxygen consumption (Vo2 peak). The impact of a Tai Chi Chuan (TCC) cardiac rehabilitation program for patients recovering from recent MI has yet to be assessed. Our goal is to evaluate functional capacity after a TCC-based cardiac rehabilitation program in patients with recent MI. A single-blind randomized clinical trial was conducted. The researchers who performed the tests were blinded to group allocation. Between the 14th and 21st days after hospital discharge, all patients performed a cardiopulmonary exercise testing and a laboratory blood workup. Mean age was similar (56±9 years in the TCC group and 60±9 years in the control group). Patients allocated to the intervention group performed 3 weekly sessions of TCC Beijin style for 12 weeks (n=31). The control group participated in 3 weekly sessions of full-body stretching exercises (n=30). After the 12-week study period, participants in the TCC group experienced a significant 14% increase in Vo2 peak from baseline (21.6 ± 5.2 to 24.6 ± 5.2 mL/kg per minute), whereas control participants had a nonsignificant 5% decline in Vo2 peak (20.4 ± 5.1 to 19.4 ± 4.4 mL/kg per minute). There was a significant difference between the 2 groups (P<.0001). Tai Chi Chuan practice was associated with an increase in Vo2 peak in patients with a recent MI and may constitute an effective form of cardiac rehabilitation in this patient population.

Effect of duration of data averaging interval on reported peak VO2 in patients with heart failure

AimTo describe the effect of the duration of the data averaging interval on the calculated peak oxygen uptake (VO2) reported from a symptom-limited maximal exercise test in patients with heart failure. MethodsMaximal exercise test results from 275 patients diagnosed with stable heart failure due to left ventricular systolic dysfunction (ejection fraction<45%; age: 45–75years; peak VO2: 8.0–20.0mL/kg/min), were examined. Sampling rates of 10, 20, 30 and 60s were used to calculate peak VO2, which was identified as the highest interval value that occurred during the final minute of exercise or the first interval in immediate recovery. ResultsMean peak VO2 (mL/kg/min) across the four sampling periods was as follows: 14.0±3.0 (10s), 13.7±3.0 (20s), 13.5±3.0 (30s) and 13.2±2.9 (60s) and there was a significant reduction with increasing averaging duration (p<0.0001). Peak VO2 was significantly different between the 10s and 60s sampling times (p<0.0001). Peak respiratory exchange ratio (RER) was also significantly different between 10 and 60s sampling rates (p<0.0001). Sub-analyses showed peak VO2 values in those people achieving RER>1.05 to be +0.8±0.7mL/kg/min higher than those who had not achieved RER values>1.05; similar findings, +0.8±0.7mL/kg/min, were seen in those patients achieving RER>1.10 versus those who did not. ConclusionsSampling rate method has a significant effect on calculated peak VO2 and RER. We suggest that laboratories standardize their sampling rate method to ensure consistency.

PARIS: A good start for exercise in HFPEF.

Heart failure (HF) is a complex clinical syndrome characterized by a constellation of signs and symptoms involving various organ systems. Structural and/or functional cardiac abnormalities form a cornerstone to the pathophysiology of HF. However, extracardiac dysfunction plays an equally important role in its development and progression.1 Approximately 50% or more of HF patients have HF with preserved left ventricular ejection fraction (HFPEF), and the proportion is higher among women and the elderly.2,3 The main symptoms of this entity – similar to HF with reduced ejection fraction (HFREF) – are related to exercise intolerance4–9 (dyspnea and fatigue) as well as reduced quality of life.5 However, the pathophysiology of exercise intolerance in this group of patients is not well understood. There is scarcity in HFPEF mechanistic clinical studies and relatively few data regarding its treatment.10 Exercise intolerance can be objectively expressed by reduced peak exercise oxygen consumption (VO2) measured by expired gas analysis, a technique that is valid and reproducible in patients with HFPEF.11,12 According to Fick's equation, reduced peak VO2 results from either reduced cardiac output (CO), peripheral arterial-venous oxygen difference (A-VO2 Diff), or both. Many studies have reported that endurance exercise training (EET) improves peak VO2 in patients with HFREF,13,14 and that this improvement results from favorable changes in cardiac,13,15–17 peripheral vascular,15 and skeletal muscle function.16,18–20 These changes increase oxygen delivery to, and utilization by, the active muscles (i.e., increased A-VO2 Diff). In contrast, there are only four studies of such kind in patients with HFPEF21–24 and the mechanisms of exercise training effects in this group are not known yet.

Cardiopulmonary exercise testing to evaluate the exercise capacity of patients with inoperable chronic thromboembolic pulmonary hypertension: An endothelin receptor antagonist improves the peak PETCO2

AimsThe 6-min walking distance is often used for assessing the exercise capacity under the treatment with an endothelin receptor antagonist (ERA) in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The cardiopulmonary exercise testing (CPX) was reported to be more useful for the patients with pulmonary arterial hypertension (PAH), however, few reports exist in patients with inoperable CTEPH. The aim of this study was to investigate the effects of an oral dual ERA, bosentan, on exercise capacity using CPX in patients with PAH and inoperable CTEPH. Main methodsThis study included all patients diagnosed with 17 PAH and 12 CTEPH in the World Health Organization functional classes II–IV who started treatment with bosentan therapy. They underwent CPX, which was performed before bosentan therapy and at 3 to 6months of the treatment. Key findingsIn PAH patients, peak VO2 significantly increased after the bosentan treatment (p=0.009). On the other hand, in CTEPH patients, there were no significant differences in the peak VO2. However, the peak PETCO2 was significantly increased from 23.9±5.2mmHg at baseline to 29.3±10.7mmHg after the bosentan treatment (p=0.040). In addition, peak heart rate during exercise tended to decrease after the bosentan therapy (p=0.089). SignificanceBosentan therapy improved peak PETCO2 but not peak VO2 in patients with inoperable CTEPH. These findings demonstrated that CPX is useful for assessing the exercise capacity of patients with PAH and inoperable CTEPH under the treatment with an ERA.

Effect of increasing pump speed during exercise on peak oxygen uptake in heart failure patients supported with a continuous‐flow left ventricular assist device. A double‐blind randomized study

Continuous-flow left ventricular assist device (CF-LVAD) implantation is associated with improved quality of life, but the effect on exercise capacity is less well documented. It is uncertain whether a fixed CF-LVAD pump speed, which allows for sufficient circulatory support at rest, remains adequate during exercise. The aim of this study was to evaluate the effects of fixed versus incremental pump speed on peak oxygen uptake (peak VO2) during a maximal exercise test. In CF-LVAD (HeartMate II) patients exercise testing measuring peak oxygen uptake (VO2) was performed on an ergometer bike twice in one day: once with fixed pump speed (testfix) and once with incremental pump speed (testinc). The order of testfix and testinc in each patient was determined by randomization. During testinc pump speed was increased from the baseline value by 400 rpm/2 min. Fourteen patients (aged 23–69 years) were included with a mean support duration of 465±483 days. Baseline CF-LVAD speed was 9357±238 rpm and during testinc speed was increased by a mean of 1486±775 rpm. Mean peak VO2 was significantly higher in testinc compared with testfix (15.4±5.9 mL/kg/min vs. 14.1±6.3 mL/kg/min; P=0.012), corresponding to a 9.2% increase. All exercise tests (n=28) were adequately performed with RER>1. Increasing pump speed during exercise augments peak VO2 in patients supported with CF-LVADs. An automatic speed-change function in future generations of CF-LVADs might improve functional capacity.

Feasibility and Prognostic Value of VO2peak in Patients Undergoing Hematopoietic Cell Transplantation (HCT)

AbstractAbstract 4152 Background:Peak oxygen consumption (VO2peak, in mL/kg*min) is assessed by cardiopulmonary exercise testing (CPET) and reflects overall physical fitness. VO2peak has prognostic value in healthy and chronically ill patients, including patients with solid tumor malignancies. To our knowledge, direct measurement of peak oxygen uptake has not previously been examined in patients undergoing HCT, an area in which prognostic models are needed to understand and limit treatment-related toxicity. Current HCT prognostic models measure disease-related risk or indirectly measure patient fitness by assessing comorbidity burden. The purpose of this study was to evaluate the feasibility of assessing functional status in HCT patients by exercise testing and physiological measurements, and to investigate the potential prognostic usefulness of these variables in this population. Patients and methods:We evaluated the feasibility of assessing cardiopulmonary fitness (CPET with gas exchange on cycle ergometer), body composition (Dual Energy X-ray Absorptiometry-DEXA), and physical function (6 minute walk test-6MW) in 32 patients undergoing planned HCT (10 autologous HCT patients, 11 myeloablative allogeneic HCT patients, 11 reduced intensity allogeneic HCT patients). Tests were conducted prior to receipt of conditioning chemotherapy and again at 100 days following stem cell infusion (D+100). Feasibility was determined by the ability of patients to successfully and safely complete a full set of tests. Exploratory analyses to investigate the relationships of variables with one another and with survival utilized Kruskal-Wallis and Wilcoxon Signed Rank tests, Pearson Correlation coefficients, and Cox regression analyses.Median age of the sample was 55 years (range 18–70). Sixteen patients (50%) were female. Most autologous HCT patients had myeloma (N=8, 80%) and most allogeneic HCT patients had acute leukemia (16, 72%); other diagnoses included NHL (4), CML, MDS and AA. Twenty-six patients (84%) had intermediate or late stage disease, and 16 patients (50%) had a Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) score of > 3. Results:VO2peak testing was successfully completed prior to HCT in 29 (91%) patients with no adverse events during testing. Two patients had lower limb limitations preventing participation in cycle ergometry, and one patient had baseline EKG abnormalities with exclusion per clinician discretion. No significant differences in median VO2peak were observed at baseline among patients undergoing autologous, myeloablative allogeneic, and reduced intensity allogeneic HCT (20.1 (15.20–28.0), 20.8 (9.2–35.4), and 23.8 (10.8–28.7) mL/kg*min respectively, p=0.9). Across cohorts, eight (28%) patients had a VO2peak <16ml/kg*min, which has been shown in other studies to be associated with lack of functional independence. Physical function assessed via 6MW at baseline was not significantly different between groups (448 (305–590), 480 (320–690), and 493 (313–600) meters respectively, p=0.44). Baseline VO2peak was correlated with 6MW (r=0.65, p<0.001) but not with age, HCT-CI, or other baseline variables. D+100 testing was completed in 14 (44%) patients, with significant post-HCT changes observed in median total mass (−2056g, p=0.01) and median lean mass (−1601g, p=0.01) among these 14 patients. With a median follow-up of 9 months, 24 (75%) patients were alive. When including all patients, a baseline VO2peak of > 16 mg/kg*min was associated with a lower risk for mortality after transplant (HR 0.11 (0.02–0.59), p<0.01). No associations between age (p=0.30), HCT-CI (p=0.17), or EBMT risk score (p=0.17) with post-HCT mortality were observed. The association of 6MW with post-HCT mortality approached significance (p=0.09). Conclusions:Baseline comprehensive functional and exercise testing that includes CPET with gas exchange is feasible in patients undergoing HCT, including older patients with comorbid illness and advanced disease. The feasibility and potential prognostic usefulness of D+100 testing were limited by post-HCT morbidity and logistical concerns, though data from patients undergoing testing showed significant attrition in muscle mass. Baseline VO2peak reflects underlying physiological fitness and may be a novel prognostic marker in patients undergoing HCT. Larger studies are warranted to confirm this finding. Disclosures:No relevant conflicts of interest to declare.

Oxygen Uptake Efficiency Slope, Aerobic Fitness, and V˙ E –V˙CO2 Slope in Heart Failure

The oxygen uptake efficiency slope (OUES) is a promising submaximal index of exercise capacity, but its relationships to other indices characterizing physical fitness and ventilatory efficiency have not been widely investigated in heart failure. Sixty-three male patients with stable chronic heart failure performed a symptom-limited maximal exercise test on a cycle ergometer. Nineteen of them performed two exercise tests, 6 months apart. The peak oxygen uptake (VO2peak), ventilatory anaerobic threshold (VAT), OUES using all data (OUES(100)) or only the data up to the point where the RER was 1 (OUE(SRER1)), and V(E)-VCO2 slope were determined. OUES(100), OUE(SRER1), and VAT were significantly correlated with measured VO2peak (r = 0.883, r = 0.814, and r = 0.877, respectively). The Bland-Altman limits of agreement between measured VO2peak and the values predicted by calculation from OUES(100), OUE(SRER1), and VAT were ±0.46, ±0.57, and ±0.48 L·min(-1), respectively. The variation in OUE(SRER1) between the first and second tests in the 19 patients was significantly related to the variation in VO2peak but not to the variation in the V(E)-VCO2 slope. To predict VO2peak in patients with chronic heart failure, the index OUE(SRER1) is not better than the VAT. This, however, does not question the theoretical interest of its calculation because it may provide additional information on the oxygen uptake limitation steps.

The Storer-Davis-Caiozzo (SDC) VO2peak Equation Accurately Estimates VO2peak In Patients Awaiting Surgery For Abdominal Tumors

The Storer-Davis-Caiozzo (SDC) VO2peak Equation Accurately Estimates VO2peak In Patients Awaiting Surgery For Abdominal Tumors

Effects of Modality Change and Transplant on Peak Oxygen Uptake in Patients With Kidney Failure

Exercise capacity as measured by peak oxygen uptake (Vo₂(peak)) is low in hemodialysis patients. The present study assesses determinants of VO₂(peak) in patients with chronic kidney failure who either changed kidney replacement modality to frequent hemodialysis therapy or received a kidney transplant. Cohort study with assessment at baseline and 6 months after modality change. Participants included nondiabetic individuals receiving conventional hemodialysis who: (1) remained on conventional hemodialysis therapy (n = 13), (2) changed to short daily hemodialysis therapy (n = 10), or (3) received a transplant (n = 5) and (4) individuals who underwent a pre-emptive transplant (n = 15). Additionally, 34 healthy controls were assessed at baseline only. Modality change. Exercise capacity, assessed using the physiologic components of the Fick equation (Vo₂ = cardiac output × a-vo₂(dif), where a-vo₂(dif) is arterial to venous oxygen difference) was determined using measurement of Vo₂(peak) and cardiac output during symptom-limited exercise testing. Analysis of covariance was used to compare differences in changes in Vo₂(peak), cardiac output, heart rate, stroke volume, and a-vo₂(dif) at peak exercise between participants who remained on hemodialysis therapy and those who underwent transplant. Transplant was the only modality change associated with a significant change in Vo₂(peak), occurring as a result of increased peak cardiac output and reflecting increased heart rate without a change in peak a-vo₂(dif) despite increased hemoglobin levels. There were no differences in participants who changed to daily hemodialysis therapy compared with those who remained on conventional hemodialysis therapy. Small nonrandomized study. Vo₂(peak) increases significantly after kidney transplant, but not with daily hemodialysis; this improvement reflects increased peak cardiac output through increased peak heart rate. Despite statistical significance, the increase in Vo₂(peak) was not clinically significant, suggesting the need for interventions such as exercise training to increase Vo₂(peak) in all patients regardless of treatment modality.

Determinants of Exercise Capacity in CKD Patients Treated With Hemodialysis

There are many ways to measure physical functioning. Oxygen uptake at peak exercise is considered to be the most objective or 'gold-standard' measure and is determined by the integrated functioning of multiple physiological systems. Renal failure can affect the functioning of several of these systems which results in low levels of peak oxygen uptake. This review examines the determinants of oxygen uptake as defined by the Fick Equation, and presents data from studies that have reported these physiological measures. It becomes clear that there are many factors that may limit peak oxygen uptake in these patients and any one mechanism may be difficult to identify.

Peak Cardiac Power Output, Measured Noninvasively, Is a Powerful Predictor of Outcome in Chronic Heart Failure

The cardiac output (CO) response to exercise and other invasively derived hemodynamic variables has been variably described to provide better prognostication than peak V(O(2)) in patients with chronic heart failure. Using noninvasive measurements of CO during exercise, we compared the prognostic value of peak CO and cardiac power to peak V(O(2)) in chronic heart failure patients. One hundred seventy-one consecutive patients with chronic heart failure underwent symptom limited bicycle exercise with noninvasive estimation of CO using an inert gas rebreathing method. An accurate measure of peak CO was obtained in 148 patients (85% of patients; mean age, 53+/-14 years; 80% male; left ventricular ejection fraction, 24+/-12%; ischemic etiology, 34%). Peak cardiac power was derived from the product of the peak mean arterial blood pressure and CO divided by 451. End points consisted of death, urgent heart transplant, or left ventricular assist device implantation. Duration of follow-up averaged 337+/-252 days (median, 295 days). Univariate and multivariate analysis were performed. The variables analyzed included peak V(O(2)), peak CO, peak cardiac power, V(E)/V(CO(2)) slope, and V(O(2)) at anaerobic threshold. Event-free survival for the entire cohort was 83% with 5 deaths, 4 left ventricular assist device implants, and 16 urgent transplants. Peak V(O(2)) was 12.9+/-4.5 mL/kg per min, and peak cardiac power was 1.7+/-0.9 W. Peak V(O(2)), peak CO, peak cardiac power, V(E)/V(CO(2)) slope, and V(O(2)) at anaerobic threshold were predictive of outcome on univariate analysis. On multivariate analysis, peak cardiac power and peak CO were predictive of outcome with peak cardiac power being the most powerful independent predictor of outcome (P=0.01). Peak cardiac power, measured noninvasively, is an independent predictor of outcome that can enhance the prognostic power of peak V(O(2)) in the evaluation of patients with heart failure.

Impact of Impaired Aerobic Capacity on Liver Transplant Candidates

Oxygen consumption at peak exercise (peak VO2) is the most accurate index of aerobic capacity (AC), which reflects the physical condition of an individual and is currently considered the gold standard for cardiorespiratory fitness. Evaluation of peak VO2 to identify high-risk candidates for liver transplantation (LT) may represent an interesting approach. The aims of this study were (a) to describe AC and identify factors independently associated with peak VO2; (b) to analyze the prognostic value of peak VO2 in patients referred for preliminary evaluation of LT; and (c) to provide preliminary data on the influence of peak VO2 on length of hospitalization and the need for oxygen support after LT. Peak VO2 was determined in patients referred for preliminary evaluation for LT. One hundred thirty-five candidates were included. More than half had severe alterations in peak VO2. Age, gender, model-for-end-stage liver disease (MELD) score, tobacco use, and hemoglobin were independently associated with peak VO2. Candidates with severe alterations in peak VO2 had a lower 1-year survival than others. Model-for-end-stage liver disease score and peak VO2 were independently associated with survival. In patients with a MELD above 17, those with severe alterations of peak VO2 AC had lower 1-year survival than the others. Among patients who underwent LT, those with severe impairment of peak VO2 showed a trend toward a higher mean length of hospitalization after LT and had significantly longer need for oxygen support. Peak VO2 is severely impaired in candidates for LT and affects survival and post-LT course. Perioperative respiratory rehabilitation programs validated in lung and heart transplantation must be tested.

The 6-Min Walk Distance, Peak Oxygen Uptake, and Mortality in COPD

In patients with COPD, the maximal oxygen uptake (Vo2) measured at peak exercise and the 6-min walk distance (6MWD) have been associated with survival; however, no study has compared the strength of the association in the same patients. In this study, we compared the association between the 6MWD and peak Vo2 and mortality in 365 patients with COPD. Patients' cardiopulmonary cycle ergometry test results and 6MWD were determined at entry, and patients were followed up for a mean period of 67 months. There were 171 deaths. Compared with survivors, nonsurvivors were older (mean [+/- SD] age, 67.9 +/- 8 vs 65.9 +/- 8 years, respectively; p = 0.008), had worse mean FEV1 (36.5 +/- 12 vs 42.6 +/- 14 L, respectively; p = 0.02), had lower mean peak Vo2 (9.8 +/- 3 vs 11.8 +/- 3.6 mL/Kg/min, respectively; p < 0.0001), lower mean 6MWD (312 +/- 104 vs 377 +/- 95 m, respectively; p < 0.0001), and lower mean exercise minute ventilation (37.4 +/- 12 vs 42.3 +/- 13 L/min, respectively; p = 0.004). Univariate analysis showed that peak Vo2 and 6MWD as well as comorbidity, FEV1, and body mass index were associated with death. Logistic regression analysis with mortality as the dependent variable revealed that 6MWD (hazard ratio [HR], 0.996; 95% confidence interval [CI], 0.993 to 0.999; p < 0.01) had a stronger association than the peak Vo2 (HR, 0.971; 95% CI, 0.959 to 1.000; p = 0.050) with mortality. This study shows the 6MWD is as good predictor of mortality as the peak Vo2 in patients with COPD.

88 Long-term prognostic value of peak VO2 in patients with heart failure on chronic beta-blocker therapy

88 Long-term prognostic value of peak VO2 in patients with heart failure on chronic beta-blocker therapy

High Versus Moderate Intensity Exercise Training after Coronary Bypass Surgery

PURPOSE: To determine the effect of high versus moderate intensity exercise training in a residential rehabilitation setting upon peak oxygen uptake (VO2peak). METHODS: 57 coronary artery bypass graft (CABG) patients referred to a residential rehabilitation centre 4–15 weeks post surgery were randomised to moderate (n = 29) or high (n = 28) intensity exercise training. Subjects walked on a treadmill 5 times per week during a 4 weeks rehabilitation period. The moderate intensity group carried out 46 minutes of walking at 70% of peak heart rate at pre-test (HRpeak), while the high intensity group carried out 4×4 minutes intervals at 85–95% of HRpeak with lower intensity periods in between. Total training volume was similar in both groups. In addition, the subjects participated in the ordinary training program at the centre, which consisted of both high and moderate intensity training. At discharge, the subjects were advised to continue training with the intensity they were randomised to. Subjects were re-tested after the rehabilitation period and again 6 months after discharge from the centre. SUMMARY OF RESULTS: Subjects performed on average 17 supervised treadmill sessions (range 14–18). VO2peak increased significantly in both groups, from 26.3 (SD 5.3) to 28.6 (SD 5.7) ml/min/kg in the moderate intensity group (p<0.0001) and from 27.3 (SD 4.4) to 30.5 (5.5) ml/min/kg (p<0.0001) in the high intensity group, with no significant difference between groups. So far, 17 patients in each group have been tested 6 months after the rehabilitation period: The high intensity group showed a significant increase from post-test of 6.6% (SD 8.7) in VO2peak (p < 0.005), while the moderate group showed no increase (0.6%, SD 9.6, p = 0.7). No significant changes in blood cholesterol were observed during the stay in the two groups. As a total however, the patients had a significant increase of 6.6% (p<0.05) in HDL. CONCLUSION: Moderate and high intensity training, in addition to a regular rehabilitation program, equally increases VO2peak in patients undergoing 4 weeks residential rehabilitation after coronary bypass surgery. Preliminary 6 months follow-up data suggest a further increase in the high intensity group only.

UPPER BODY STRENGTH TRAINING VS CONVENTIONAL EXERCISE REHABILITATION IN PATIENTS WITH PERIPHERAL VASCULAR DISEASE (PVD)

PURPOSE Upper body cycle ergometry increases walking distance in patients with claudication. This study compared the effects of 6 wk upper body strength training programme (UBST; n=9) to conventional (walking, cycling, circuit) exercise rehabilitation (ER; n=9) in patients with PVD. A third group of patients with PVD were instructed to walk as “much as possible”, served as the control group (CONT; n=8). METHODS Before and after intervention all groups performed a standard graded treadmill exercise to determine maximal walking distance (MWD), pain free walking distance (PFWD) and VO2peak, ventilation (VE), and respiratory exchange ratio (RER). RESULTS At baseline, all parameters were similar in UBS, CER and CONT groups. After intervention, MWD in ER increased from 300±198 to 514±226 m; ([mean±SD]; P < 0.05) but was unchanged in the UBST (390±211 to 399±186 m; P=NS) and CONT group (460±200 vs. 430±151 m; P=NS). Similarly VO2peak increased after ER (14.7±3.0 vs. 19.4±5.0 mlO2/kg/min; P < 0.05) but was unchanged in the UBST group (19.6±5.0 vs. 18.7±6.0 mlO2/kg/min; P=NS) and CONT groups (18.2±4.0 vs. 17.6±3.0 mlO2/kg/min;P=NS) following intervention. PFWD tended to increase after intervention in ER (126±156 vs. 256±187 m; P=0.07) and USST (128±121 vs. 202±175 m; P=0.07) but was unchanged in the CONT group (175±123 vs. 175±135 m). Peak RER and VE, did not change in any group following intervention. CONCLUSIONS 6 wks of ER improved MWD and VO2peak in patients with PVD whereas UBST alone was ineffective. Thus conventional programmes should be prescribed to improve walking tolerance in patients with PVD. However verbal encouragement to exercise alone without follow-up is an ineffective form of management.