Respiratory gas kinetics in patients with congestive heart failure during recovery from peak exercise

Abstract Background Cardiopulmonary Exercise Testing (CPX) is essential for the assessment of exercise capacity for patients with Chronic Heart Failure (CHF). Respiratory gas and hemodynamic parameters such as Ventilatory Efficiency (VE/VCO2 slope), peak oxygen uptake (peak VO2), and heart rate recovery are established diagnostic and prognostic markers for clinical populations. Previous studies have suggested the clinical value of metrics related to respiratory gas collected during recovery from peak exercise, particularly recovery time to 50% (T1/2) of peak VO2. The current study explores these metrics in detail during recovery from peak exercise in CHF. Methods Patients with CHF who were referred for CPX and healthy individuals without formal diagnoses were assessed for inclusion. All subjects performed CPX on cycle ergometers to volitional exhaustion and were monitored for at least five minutes of recovery. CPX data were analyzed for overshoot of respiratory exchange ratio (RER=VCO2/VO2), ventilatory equivalent for oxygen (VE/VO2), end-tidal partial pressure of oxygen (PETO2), and T1/2 of peak VO2 and VCO2. Results Thirty-two patients with CHF and 30 controls were included. Peak VO2 differed significantly between patients and controls (13.5 ± 3.8 vs. 32.5 ± 9.8 mL/Kg*min−1, p < 0.001). Mean Left Ventricular Ejection Fraction (LVEF) was 35.9 ± 9.8% for patients with CHF compared to 61.1 ± 8.2% in the control group. The T1/2 of VO2, VCO2 and VE was significantly higher in patients (111.3 ± 51.0, 132.0 ± 38.8 and 155.6 ± 45.5s) than in controls (58.08 ± 13.2, 74.3 ± 21.1, 96.7 ± 36.8s; p < 0.001) while the overshoot of PETO2, VE/VO2 and RER was significantly lower in patients (7.2 ± 3.3, 41.9 ± 29.1 and 25.0 ± 13.6%) than in controls (10.1 ± 4.6, 62.1 ± 17.7 and 38.7 ± 15.1%; all p < 0.01). Most of the recovery metrics were significantly correlated with peak VO2 in CHF patients, but not with LVEF. Conclusions Patients with CHF have a significantly blunted recovery from peak exercise. This is reflected in delays of VO2, VCO2, VE, PETO2, RER and VE/VO2, reflecting a greater energy required to return to baseline. Abnormal respiratory gas kinetics in CHF was negatively correlated with peak VO2 but not baseline LVEF.

Application of the Animal Energy Metabolism Monitoring System (AEMMS) in Acute Alcoholic Liver Injury with the Treatment of Acupuncture / 世界科学技术-中医药现代化

This study aimed to explore the value of animal energy metabolism monitoring system (AEMMS) to evaluate the energy metabolism of acute alcohol liver injury in rat with the treatment of acupuncture.Tirty rats were randomly divided into the control group,the model group and the EA group.The model group and the EA group were gavaged with 50％ ethanol for the establishment of the animal model of acute alcoholic liver injury.EA was given by needling Zusanli (ST-36) 30 min after intragastic administration every day in the EA group.The treatment of acupuncture continued 3 days.In addition,the RER,heat,feeding and drinking were continuously recorded for 96 h in each group at the same time by AEMMS.As a result,the RER,feeding and drinking indices significantly decreased in rats with ALI with an increase in the heat index.There was an up-going tendency of the RER,feeding and drinking indices,and a declined tendency of the heat index in the model rats after EA treatment.It was concluded that AEMMS presented a practical value in the study of the energy metabolism of rats with ALI with the treatment of acupuncture.

An age-dependent alteration of the respiratory exchange ratio in the db/db mouse / 한국실험동물학회지

The leptin receptor-deficient db/db mouse is a rodent model of type 2 diabetes and obesity. Diabetes in db/db mice shows an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. However, there is insufficient data on agedependent changes of energy metabolism in db/db mice. We demonstrated an age-dependent decrease in the respiratory exchange ratio (RER), calculated by a ratio of VO2/VCO2, in db/db mice. The RER determined by indirect calorimetry, was 1.03 in db/db mice under 6 weeks of age, which were similar to those in heterozygote (db/+) and wild-type (+/+) mice. However, RER decreased from approximately 0.9 to 0.8 by 10 weeks of age and subsequently returned to approximately 0.9 at 22 weeks of age. The changes in RER were concurrent with the alterations in body weight and blood glucose level. However, other metabolic indicators such as glucose tolerance, changes in body fat mass, and urinary glucose levels, did not change with age. The results suggested that the energy source utilized in db/db mice changed with the age-related progression of diabetes.

THE COMPARISON OF POST EXERCISE OXYGEN CONSUMPTION BETWEEN TWO DIFFERENCE SUPRAMAXIMAL EXERCISES / 体力科学

Exercise intensity has been identified as a major determinant of the excess post-exercise oxygen consumption (EPOC). However, no studies have compared the prolonged EPOC after supramaximal intermittent exercise and supramaximal continuous exercise. Six young healthy male [age=26±3 (mean±SD) yr ; stature=175.4±5.7 cm ; body weight=66.8±6.7 kg ; maximal oxygen uptake (VO₂max)=44.1±8.5 ml/kg/min] xercised on separate days on a cycle ergometer at two equated total energy expenditures (intermittent exercise : 7×30-second intervals at 150%VO₂max with intervening 15-seconds rest periods ; continuous exercise : 5 min at 105%VO₂max) and then sat quietly in an armchair for 3h. A control trial without any exercise was also performed in a counterbalanced research design. The VO₂, carbon dioxide output (VCO₂), pulmonary ventilation (VE), respiratory exchange ratio (RER), heart rate (HR) and blood lactate concentration (LA) were measured before exercise, during exercise and during the 3-h recovery period. The mean VO₂ after intermittent trial at 150%VO₂max were higher than these of the control trial and the continuous trials at 105%VO₂max for 3-h recovery periods (p<0.05). The 3-h EPOC value for intermittent exercise trial (10.5±2.4L) was significantly greater than that of continuous exercise trial (4.8±2.7L) (p<0.05). The mean RER values for intermittent exercise trial were significantly lower than those of the control trial during 60-180 min post-exercise (p<0.05). We examined the effect of supramaximal exercise intensity on the magnitude of 3-h EPOC after 12-fasting. In the present study, 3-h EPOC was significantly greater for supramaximal intermittent exercise compared with the supramaximal continuous exercise when the amounts of work output performed are same. Therefore, our results indicate that exercise intensity may be a primary factor of 3-h EPOC even in a supramaximal exercise and that one of mechanisms for the 3-h EPOC would be related to the promoted lipid metabolism.

Effect of walking speed on energy metabolism in middle-aged women / 体力科学

This study evaluated the relationship between walking speed and energy metabolism. The speed at which energy consumption per km of walking was lowest was defined as“economical speed”; the speed at which each subject felt most natural was defined as“comfortable speed”; and the fastest speed at which each subject was able to walk was defined as“fast speed”.<BR>Energy consumption during 60-minutes of walking was 342±11 kcal at fast speed, 248±13 kcal at comfortable speed, and 201± 17 kcal at economical speed. The value at fast speed was significantly higher than at other speeds (P<0.001) . As for source of energy consumption, energy derived from carbohydrates was 233±16 kcal at fast speed, accounting for 68% of total energy consumption, 149±19 kcal at comfortable speed, and 109±13 kcal at economical speed. Energy derived from fat was 109±10 kcal at fast speed, 99±14 kcal at comfortable speed, and 92±12 kcal at economical speed, with no significant difference among the 3 speeds. No difference was observed among the 3 speeds in change in plasma lipid levels after walking compared with before walking.