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Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients.

BACKGROUND: Previous studies have demonstrated that in patients with coronary artery disease (CAD) upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection are correlated with a diminished stress dependent left ventricular function. Magnesium supplementation improves endothelial function, exercise tolerance, and exercise induced chest pain in patients with CAD. PURPOSE: We studied the effects of oral magnesium therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD. METHODS: In a double blind controlled trial, 53 male patients with stable CAD were randomised to either oral magnesium 15 mmol twice daily (n = 28, age 61+/-9 years, height 171+/-7 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 7) or placebo (n = 25, age 58+/-10 years, height 172+/-6 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 6) for 6 months. Maximal oxygen uptake (VO2max), the degree and direction of the deflection of the HR performance curve described as factor k<0 (upward deflection), and the left ventricular ejection fraction (LVEF) were the outcomes measured. RESULTS: Magnesium therapy for 6 months significantly increased intracellular magnesium levels (32.7+/-2.5 v 35.6+/-2.1 mEq/l, p<0.001) compared to placebo (33.1+/-3.1.9 v 33.8+/-2.0 mEq/l, NS), VO2max (28.3+/-6.2 v 30.6+/-7.1 ml/kg/min, p<0.001; 29.3+/-5.4 v 29.6+/-5.2 ml/kg/min, NS), factor k (-0.298+/-0.242 v -0.208+/-0.260, p<0.05; -0.269+/-0.336 v -0.272+/-0.335, NS), and LVEF (58+/-11 v 67+/-10%, p<0.001; 55+/-11 v 54+/-12%, NS). CONCLUSION: The present study supports the intake of oral magnesium and its favourable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.

Administration, Oral↗

Exercise tolerance testing to screen for coronary heart disease: a systematic review for the technical support for the U.S. Preventive Services Task Force.

BACKGROUND: Coronary heart disease is the leading cause of morbidity and mortality in the United States. Exercise tolerance testing has been proposed as a means of better identifying asymptomatic patients at high risk for coronary heart disease events. PURPOSE: To review the evidence on the use of exercise tolerance testing to screen adults with no history of cardiovascular disease for coronary heart disease. DATA SOURCES: The MEDLINE database from 1966 through February 2003, hand-searching of bibliographies, and expert input. STUDY SELECTION: Eligible studies evaluated the benefits or harms of exercise tolerance testing when added to traditional risk assessment for adults with no known history of cardiovascular events. DATA EXTRACTION: One reviewer extracted information from eligible articles into evidence tables, and another reviewer checked the tables. Disagreements were resolved by consensus. DATA SYNTHESIS: No study has directly examined the effect of screening asymptomatic patients with exercise tolerance testing on coronary heart disease outcomes or risk-reducing behaviors or therapies. Multiple cohort studies demonstrate that screening exercise tolerance testing identifies a small proportion of asymptomatic persons (up to 2.7% of those screened) with severe coronary artery obstruction who may benefit from revascularization. Several large prospective cohort studies, conducted principally in middle-aged men, suggest that exercise tolerance testing can provide independent prognostic information about the risk for future coronary heart disease events (relative risk with abnormal exercise tolerance testing, 2.0 to 5.0). However, when the risk for coronary heart disease events is low, most positive findings will be false and may result in unnecessary further testing or worry. The risk level at which the benefits of additional prognostic information outweigh the harms of false-positive results is unclear and requires further study. CONCLUSIONS: Although screening exercise tolerance testing detects severe coronary artery obstruction in a small proportion of persons screened and can provide independent prognostic information about the risk for coronary heart disease events, the effect of this information on clinical management and disease outcomes in asymptomatic patients is unclear.

Coronary Disease↗

[The effect of amlodipine on structure and function of the heart and exercise tolerance in patients with hypertension].

UNLABELLED: The aim of the study was to assess whether the hypotensive activity of amlodipine is associated with regression of left ventricular hypertrophy and improvement of impaired LV or right ventricular (RV) diastolic function or increasing of tolerance of physical activity in hypertensive patients. Assessment of left ventricular structure, systolic and diastolic function as well as RV diastolic dimension and diastolic function were performed in 24 patients with mild-to-moderate hypertension before administration of amlodipine and 3, 6 and 9 months of the treatment. In order to assess the tolerance of physical activity, incremental treadmill exercise testing was performed at baseline and after 6 and 9 months of the therapy with amlodipine. RESULTS: During 9 months of the therapy with amlodipine no significant change in indexes of LV mass or in LVM was observed. Similarly amlodipine did not influence the parameters of LV or RV diastolic function in studied patients. However, amlodipine treatment resulted in significant increase in total exercise time (p < 0.05), total workload (p < 0.01) measured in METs and decrease in diastolic blood pressure during exercise test. CONCLUSION: The nine months of the therapy with amlodipine resulted in significant improvement in exercise tolerance. Total exercise duration and total workload measured in METs significantly increased. During this time of the therapy no significant changes in LV structure or LV and RV diastolic function were observed. One can make an assumption that amlodipine inhibits progression of structural and functional derangement in hypertensive patients.

Adult↗

[Effect of exercise tolerance test on hemostasis in patients with and without coronary heart disease].

BACKGROUND: Physical exercise leads to an elevated coagulation activity with a possibly disturbed hemostatic balance. Therefore patients with coronary heart disease have a potentially increased risk of thromboembolic events after a bicycle exercise tolerance test, that is frequently performed for diagnostic reasons. PATIENTS AND METHODS: Patients with angiographically known coronary heart disease (Group I: n = 49; age 59 years; male = 42, female = 7) were investigated in comparison to a healthy cohort (Group 2: n = 51; age 53 years; male = 44, female = 7) to study the influence of a standardized exercise tolerance test on hemostatic variables. Blood samples were taken before and after exercise. RESULTS: No significant changes were found for any investigated parameter between both groups. However, 3 parameters did change significantly within the groups: factor VIII rose in Group 1 from 132 to 156% and in Group 2 from 106 to 136% and the von Willebrand factor rose in Group 1 from 230 to 249% and in Group 2 from 228 to 247%. An elevated fibrinolytic potential was found with an increase of plasminogen-alpha 2-antiplasmin in Group 1 from 251 to 401 micrograms/l and in Group 2 from 247 to 350 micrograms/l. CONCLUSION: The findings underline the clinical presumption that exercise tolerance test does not increase the risk for thromboembolic complications in patients with coronary heart disease in comparison to patients without coronary heart disease, as long as the exercise tolerance test is performed in a standardized way and under aerobe conditions.

Antifibrinolytic Agents↗

Usefulness of mitral annular velocity in predicting exercise tolerance in patients with impaired left ventricular systolic function.

Left ventricular (LV) diastolic function is 1 of the determinants of exercise tolerance. However, the relation between early diastolic velocity of the mitral annulus (Ea) obtained by tissue Doppler imaging and exercise tolerance is unknown in patients with impaired LV systolic function. To investigate the feasibility of evaluating exercise tolerance using tissue Doppler imaging, we studied 53 consecutive patients (mean age 58 +/- 14 years) with a LV ejection fraction of <50% (mean 37 +/- 9%). We measured the peak early diastolic velocity of transmitral flow (E) and Ea at the lateral border of the mitral annulus and then calculated the E/Ea ratio. After echocardiography, we measured the peak oxygen consumption and anaerobic threshold (AT) by cardiopulmonary exercise testing. Of all the echocardiographic parameters, the best correlation for AT was the E/Ea ratio (r = -0.74, p <0.001). Peak oxygen consumption correlated well with Ea and the E/Ea ratio (r = 0.64 and r = -0.68, respectively, p <0.001). The AT and peak oxygen consumption did not correlate with conventional Doppler indexes. Using an AT of 8 ml/min/kg as the cutoff to separate severe exercise intolerance from normal, mild, or moderate exercise intolerance, a receiver-operating characteristic curve showed that an E/Ea ratio of >11.3 had the best combination of sensitivity (88%) and specificity (86%). Exercise tolerance correlated with the E/Ea ratio in patients with impaired LV systolic function. In conclusion, the evaluation of LV diastolic function using tissue Doppler imaging is useful for predicting exercise tolerance in patients with heart failure.

Adult↗

Relation between left ventricular diastolic function and exercise tolerance in patients with left ventricular dysfunction.

Previous studies show no correlation between resting systolic left ventricular performance assessed as the ejection fraction and exercise tolerance. This study examined the relation between left ventricular diastolic performance and exercise tolerance in 63 patients with left ventricular dysfunction (ejection fraction less than 50%) due to known or suspected coronary artery disease. The 51 men and 12 women, aged 54 +/- 8 years (mean +/- standard deviation), underwent symptom-limited upright exercise testing on a bicycle ergometer. The exercise end-points were angina (n:5), dyspnea (n:16), and fatigue (n:42). The patients were divided into three groups: group 1 (n:28) with normal exercise tolerance (9.5 +/- 2.4 minutes), group 2 (n:18) with mild exercise intolerance (5.8 +/- 0.5 minutes), and group 3 (n:17) had severe exercise intolerance (3.7 +/- 0.9 minutes). The three groups did not differ in age, ejection fraction, end-diastolic volume, exercise end-point, exercise heart rate, and left ventricular peak filling rate at rest. The exercise peak filling rate was, however, significantly higher in group 1 (p = 0.03). Stepwise multivariate discriminant analysis of important variables identified the exercise peak filling rate as the only predictor of exercise tolerance (F = 6.0). Thus, variation in exercise peak filling rate may in part explain the variability of exercise tolerance in patients with left ventricular dysfunction; patients with preserved exercise capacity have higher exercise peak filling rate than those with exercise intolerance.

Adult↗

Effects of an intensive 4-week summer camp on cystic fibrosis: pulmonary function, exercise tolerance, and nutrition.

STUDY OBJECTIVES: Cystic fibrosis (CF) patients prefer exercise to most other forms of therapy, although objective improvement remains controversial. Israeli CF patients have attended a summer program in Switzerland for many years with subjective improvement. However, CF camps worldwide have been cancelled recently, due to fears of cross-infection with resistant organisms. Therefore, we evaluated the effect of attending the camp on pulmonary function, exercise tolerance, and nutritional state in CF patients. DESIGN: Weight, resting pulmonary function, incremental exercise test results, and sputum culture findings were assessed before and after a 4-week intensive summer camp. SETTING: Davos, Switzerland (altitude, 1,500 m). PATIENTS: Thirteen Israeli CF patients (seven women and six men) with an age range of 9 to 25 years who had mild-to-moderate lung disease. No patients had Burkholderia cepacia detected in their sputum. INTERVENTIONS: The program included a high-calorie diet, chest physiotherapy, daily mountain climbing, and indoor activities. Arterial oxygen saturation (SaO(2)) was maintained at > 88% during exertion. RESULTS: Exercise tolerance improved significantly. The peak work capacity increased by 12.7%, the maximal oxygen uptake increased by 10%, and minute ventilation increased by 18.5% (p < 0.0005). Of the calculated parameters, the anaerobic threshold improved by 17%. Ventilation was always the limiting factor during exercise, although it improved. There was no significant change in resting lung function and pulse or in SaO(2) decline at maximal exercise. The mean weight gain was 1 kg. No patient acquired B cepacia. CONCLUSIONS: An intensive summer camp improved exercise tolerance and nutrition in CF patients. This may explain improved patient well-being despite unchanged values for resting lung function. The reinstitution of summer camps, with special care to avoid cross-infection, should be considered.

Adolescent↗

Improvement of exercise tolerance by single lead VDD pacemaker: evaluation using cardiopulmonary exercise test.

We used a cardiopulmonary test to assess the physiological benefit of single lead VDD pacing in ten patients (six men, four women; aged 32-84 years, mean 69 years) with atrioventricular block. Maximal symptom-limited treadmill exercise test using a ramp protocol was performed under VDD and VVIR or VVI pacing (VVI) in random sequence. The pacemaker was then programmed to the VDD mode, and Holter ECG was recorded in nine patients. Compared with findings during the VVI, the VDD mode had a greater chronotropic response (mean maximal heart rate, VDD 106 +/- 17 beats/min vs VVI 79 +/- 19 beats/min, P = 0.03), and was associated with prolongation of exercise duration (VDD 11.2 +/- 2.9 minute vs VVI 10.5 +/- 3.1 minute; P = 0.01), and the onset of anaerobic threshold at a higher oxygen uptake (VDD 12.4 +/- 3.4 mL/min per kilogram vs VVI 10.0 +/- 2.1 mL/min per kilogram; P < 0.01). Atrial sensing was recognized in almost all normal sinus P waves for all cases examined using Holter ECG. Thus, chronotropic response during exercise by VDD pacemaker improved exercise tolerance, indicating that a VDD pacemaker might be useful for patients requiring physical activity.

Adult↗

Exercise tolerance during nasal cannula and transtracheal oxygen delivery.

Previous studies have reported that exercise tolerance improves with transtracheal oxygen delivery. However, patients were not blinded to the delivery technique used, introducing a potential source of bias. The purpose of this study was to compare exercise tolerance during nasal cannula and transtracheal delivery using a randomized double-blinded technique. Subjects (n = 11) performed 12-min walks on the same day while receiving nasal cannula and transtracheal delivery. Nine of 11 subjects walked farther with transtracheal delivery, a significant increase (p less than 0.01). Mean increase in walk distance was 95 +/- 86 feet. In addition, a trend was seen toward greater improvement in walk distance with greater flows through the catheter (r = 0.58, p less than 0.06). Time into the walk when desaturation (SaO2 less than 90%) first occurred was not significantly different. We conclude that exercise tolerance improves when oxygen is delivered by transtracheal catheter. This improvement is unrelated to an increase in SaO2. We speculate that the increase in exercise tolerance may be related to other physiologic effects of flow through the catheter.

Aged↗

Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest.

Expiratory flow limitation promotes dynamic hyperinflation during exercise in chronic obstructive pulmonary disease (COPD) patients with a consequent reduction in inspiratory capacity (IC), limiting their exercise tolerance. Therefore, the exercise capacity of patients with tidal expiratory flow limitation (FL) at rest should depend on the magnitude of IC. The presented study was designed to evaluate the role of FL on the relationship between resting IC, other respiratory function variables and exercise performance in COPD patients. Fifty-two patients were included in the study. Negative expiratory pressure (NEP) uptake (VO2,max) were measured during an incremental symptom-limited cycle exercise. Twenty-nine patients were FL at rest. The IC was normal in all non-FL patients, while in most FL subjects it was decreased. Both WRmax and VO2,max were lower in FL patients (p<0.001, each). A close relationship of WRmax and O2,max to IC was found (r=0.73 and 0.75, respectively; p<0.0001, each). In the whole group, stepwise regression analysis selected IC and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (% predicted) as the only significant contributors to exercise tolerance. Subgroup analysis showed that IC was the sole predictor in FL patients, and FEV1/FVC in non-FL patients. Detection of flow limitation provides useful information on the factors that influence exercise capacity in chronic obstructive pulmonary disease patients. Accordingly, in patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.

Aged↗

Exercise tolerance in patients with Ebstein's anomaly.

OBJECTIVES: The purpose of this study was to identify the determinants of exercise tolerance in patients with Ebstein's anomaly. BACKGROUND: Patients with Ebstein's anomaly of the tricuspid valve may have exercise limitation that improves after surgical repair. METHODS: One hundred seventeen patients performed cycle ergometry for a total of 124 tests (preoperative test in 76 patients, postoperative test in 23, test but no operation in 18, preoperative and postoperative test in 7). Multiple linear regression analysis was used to identify predictors of maximal oxygen uptake, oxygen saturation and heart rate at peak exercise. RESULTS: Age at the time of exercise ranged from 6 to 60 years (median 15). An atrial septal defect was present in 67 patients (88%) preoperatively. Compared with the preoperative group, the postoperative group had significantly higher maximal oxygen uptake (mean [+/- SD] 20.5 +/- 7.4 vs. 25.3 +/- 7.0 ml/kg body weight per min, p = 0.006). Postoperative rest and exercise blood oxygen saturation was higher than that measured preoperatively (p = 0.0001). Six of seven patients tested before and after the operation showed improved exercise tolerance. Preoperatively, major predictors of maximal oxygen uptake were oxygen saturation at rest (p = 0.01) and age (p = 0.0001). Preoperatively, the major predictor of oxygen saturation at peak exercise was rest oxygen saturation (p = 0.0001), and major predictors of peak exercise heart rate were rest heart rate (p = 0.01) and rest oxygen saturation (p = 0.01). In the postoperative group, predictors of maximal oxygen uptake included age at exercise testing, male gender and heart size. CONCLUSIONS: Definitive operation for Ebstein's anomaly results in improved exercise tolerance. Before the operation, rest oxygen saturation is the major predictor of exercise tolerance, oxygen saturation at peak exercise and peak heart rate. Postoperatively, age, gender and heart size influenced maximal oxygen uptake.

Adolescent↗

Assessment of exercise tolerance in chronic congestive heart failure.

In patients with chronic heart failure, exercise capacity is poorly related to cardiac hemodynamics, and peripheral circulation is an important determinant of exercise tolerance. The ability of the muscle vasculature to dilate is markedly impaired, in part, because of exaggerated neurohumoral activity increasing vascular wall stiffness. For this reason, increasing cardiac output is not sufficient to increase exercise capacity if not accompanied by improving vascular reactivity. The poor reliability and reproducibility of exercise tolerance assessed by maximal exercise duration or maximal attained work load (particularly on a treadmill) has led to widespread measurement of respiratory gas during exercise. Peak oxygen consumption (peak VO2), even if it is symptom-limited, has been shown to be a very reproducible criterion of exercise tolerance; moreover, because VO2 is the product of cardiac output and arteriovenous oxygen difference, it also has a qualitative hemodynamic significance. Ventilatory threshold can be determined before maximal exercise; however, problems of determination limit the practical value of this criterion. Unfortunately, peak VO2 lacks sensitivity to detect minor improvement or impairment of symptoms during daily life, although these are significant to the patient. Submaximal exercises have been proposed for this purpose and are currently being evaluated.

Exercise Test↗

Noninvasive ventilation during exercise training improves exercise tolerance in patients with chronic obstructive pulmonary disease.

PURPOSE: In patients with chronic obstructive pulmonary disease, pulmonary rehabilitation has been demonstrated to increase exercise capacity and reduce dyspnea. In the most disabled patients, the intensity of exercise during the training sessions is limited by ventilatory pump capacity. This study therefore evaluated the beneficial effect of noninvasive ventilation (NIV) support during the rehabilitation sessions on exercise tolerance. METHODS: This study included 14 patients with stabilized chronic obstructive pulmonary disease, ages 63 +/- 7 years, with a forced expiratory volume in 1 second (FEV(1)) 31.5% +/- 9.2% of predicted value. All 14 patients participated in an outpatient pulmonary rehabilitation program. Seven of the patients trained with NIV during the exercise sessions (NIV group), whereas the remaining seven patients breathed spontaneously (control group). Exercise tolerance was evaluated during an incremental exercise test and during constant work rate exercise at 75% of peak oxygen consumption (VO(2)) before and after the training program. RESULTS: The application of noninvasive ventilation increased exercise tolerance, reduced dyspnea, and prevented exercise-induced oxygen desaturation both before and after training. The pressure support was well tolerated by all the patients during the course of the training program. In the NIV group, training induced a greater improvement in peak VO(2) (18% vs 2%; P <.05) and a reduced ventilatory requirement for maximal exercise, as compared with the control group. The constant work rate exercise duration increased similarly in both groups (116% vs 81%, nonsignificant difference), and posttraining blood lactate was decreased at isotime (P <.05 in both groups), but not at the end of the exercise. CONCLUSION: In this pilot study, exercise training with noninvasive ventilation support was well tolerated and yielded further improvement in the increased exercise tolerance brought about by pulmonary rehabilitation in patients with chronic obstructive pulmonary disease. This improved exercise tolerance is partly explained by a better ventilatory adaptation during exercise.

Aged↗

[Exercise tolerance of patients under nasal intermittent positive pressure ventilation (nIPPV)].

BACKGROUND: There are only a few papers concerning with exercise tolerance of patients under nasal intermittent positive pressure ventilation (nIPPV). PATIENTS AND METHOD: Therefore since 1996 we routinely checked exercise tolerance of our nIPPV-patients when admitted to the hospital. Till March 1997 we had carried out 1386-minute walking tests (6-min WT) in 111 patients. QUESTIONS: Is there an improvement of exercise tolerance in the course of nIPPV-therapy? Are hypoxemia or hypercapnia occurring during exercise-test? METHODS: The 6-min WT was performed after one practice walk. The patients got oxygen in case of a preexisting oxygen therapy or in case of an oxygen saturation below 85% before starting. Blood gas analyses were carried out before and after stopping the test. Oxygen saturation and heart rate were registered continuously. The distance walked was measured. Twenty-one patients were tested before introducing nIPPV therapy and 3 months after home mechanical ventilation (HMV). RESULTS: The average distance walked amounted only 283 +/- 82 m (norm in healthy persons: 800 m). pO2 decreased from 69 +/- 11 to 58 +/- 12 mm Hg, pCO2 increased from 47 +/- 8 to 49 +/- 8 mm Hg. Oxygen saturation (SaO2) fell from 92 +/- 5 to 80 +/- 10%, heart rate increased from 104 +/- 18 to 130 +/- 23 beats/min. The distance walked changed not significantly from 282 +/- 109 to 308 +/- 71 m. Six patients could be tested a 3rd time after 6 months HMV. The distance walked was 315 +/- 103 m (also no significant difference). CONCLUSIONS: Everyday activity can cause severe hypoxemia in nIPPV patients. Ambulatory oxygen therapy should be considered in each case. A significant improvement of exercise tolerance under nIPPV therapy is not yet proven. Our data only show a tendency towards an increase.

Exercise Tolerance↗

Exercise tolerance as evidence of quality of life in CAD patients after coronary artery bypass by comparison with medical treatment.

The effects of coronary artery bypass (CAB) by comparison with medical treatment were evaluated on exercise tolerance in 68 patients with stable angina on effort, who underwent coronary and left ventricular cineangiography. Stress tests were performed by bicycle ergometer before medical and surgical treatment, and 6 and 12 months thereafter. Thirty-five patients (31 males and 4 females; 7 with one 70% stenosed vessel, 12 with two, 16 with three) underwent CAB; 33 (30 males and 3 females; 9 with one 70% stenosed vessel, 11 with two, 13 with three), having refused CAB, only underwent medical treatment. Both groups were given long-acting oral nitrates, none received digitalis and/or propranolol; antiarrhythmic drugs were only administered in 5% of medical and 4% of surgical patients. Both groups at 6 and 12 months follow-up showed a significant improvement in exercise tolerance. Surgical patients showed a significant increase in exercise tolerance with lower angina incidence (from the preoperative 100% to 26% and 22%, respectively), higher work load (P < .001), and a significant reduction of S-T segment depression (P < .001). Medical treatment induced an increase of exercise tolerance; angina on effort decreased (from 100% to 74% and 72%, respectively) with higher work load, and a significant reduction of S T depression (in both cases P < .001). Comparing the data of the two groups, we observed that surgical patients showed higher exercise tolerance (P < .01), lower S-T depression (P < .001) and angina incidence. Our results suggest that surgical treatment is able to improve exercise tolerance more remarkably than medical treatment.

Adult↗

Nutritional state and exercise tolerance in patients with COPD.

We hypothesized that in patients with COPD, poor nutritional status adversely influences exercise tolerance by limiting aerobic capacity of exercising muscles. In 28 patients with stable COPD, we correlated nutritional status with gas exchange indexes obtained during maximal incremental cycle ergometer exercise and with respiratory function parameters. On the basis of percent of ideal body weight (%IBW), patients were divided into three groups (GP): GP1 (n = 8, %IBW < 90); GP2 (n = 13, %IBW > or = 90 < 110); and GP3 (n = 7, %IBW > or = 110). When compared with normally nourished individuals (GPs 2 and 3), malnourished GP1 patients showed greater reduction in maximal workload and in peak O2 uptake (VO2 peak), with earlier onset of metabolic acidosis (anaerobic threshold [AT]); in addition, indexes reflecting O2 cost of ventilation were higher in GP1. Nutritional status could be correlated with exercise tolerance (VO2 peak, r = 0.82, p < 0.0001), with onset of metabolic acidosis (AT, r = 0.69, p < 0.0001) and with dead space/tidal volume ratio (VD/VT, r = -0.59, p < 0.001). Body weight was inversely correlated with indexes that are likely to reflect the increase in O2 cost of ventilation. We conclude that in patients with stable COPD, (1) malnutrition significantly affects muscle aerobic capacity and exercise tolerance, and (2) high wasted ventilation and O2 cost of ventilation may be responsible for the weight loss.

Aged↗

Effects of dihydrocodeine, alcohol, and caffeine on breathlessness and exercise tolerance in patients with chronic obstructive lung disease and normal blood gases.

We measured breathlessness and exercise tolerance in 12 patients with chronic airways obstruction, moderate or severe breathlessness, and low or normal arterial carbon dioxide tension, after the patients received dihydrocodeine, alcohol, caffeine, or placebo (through double-blind administration). Forty-five minutes after ingestion, dihydrocodeine had reduced breathlessness by 20 per cent and increased exercise tolerance by 18 per cent, with a reduction in ventilation and oxygen consumption at submaximal work loads but with no change in spirometric volumes. Oxygen also reduced breathlessness and provided additional benefit to that achieved with dihydrocodeine (at three hours after ingestion) when the two were given together: the reduction of breathlessness was 18 per cent with dihydrocodeine; 22 per cent with oxygen; and 32 per cent with dihydrocodeine plus oxygen. Alcohol increased forced vital capacity by 9 per cent, and exercise tolerance by 7 per cent. Caffeine had no deleterious effect on breathlessness or exercise tolerance, despite increasing ventilation during rest and exercise. We conclude that opiates may be valuable for the treatment of breathlessness in selected patients; further evaluation is needed, particularly of the long-term benefits and safety.

Alcoholic Beverages↗

Women with high exercise tolerance and the role of myocardial perfusion imaging.

BACKGROUND: Myocardial perfusion imaging (MPI) provides incremental diagnostic and prognostic information, even in patients with high exercise tolerance. HYPOTHESIS: Myocardial perfusion imaging provides significant diagnostic value, specifically in women with high exercise tolerance. METHODS: Our study population consisted of all women who underwent exercise MPI in our Department from January 1992 to June 1996 and reached at least Stage IV in the Bruce protocol. Patients were divided into those with known and those with possible coronary artery disease (CAD). All patients were followed for 3 years from the performance of MPI. RESULTS: Of 4,803 women who underwent myocardial perfusion imaging, 3,183 had exercise stressing, and of those, 311 reached at least Stage IV in the Bruce protocol. Of these 311 MPI scans, only 23 (7.4%) were abnormal (reversible, fixed, or mixed) and the remaining 288 (92.6%) were normal. Of the 82 patients with known CAD, 13 (15.8%) had an abnormal MPI, while only 10 (4.4%) of the 229 patients with possible CAD. No myocardial infarction or cardiac death occurred within 3 years; one patient with normal MPI needed revascularization. CONCLUSION: In women with high exercise tolerance, especially in those without already known CAD, the yield of MPI is very low. Women with high exercise tolerance have an excellent prognosis.

Cohort Studies↗