Chest
Volume 89, Issue 2, February 1986, Pages 199-205
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Cardiac Output during Exercise in Patients with COPD

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Cardiac output response was examined to determine its relationship to exercise and arterial hypoxia, pulmonary hemodynamics, and the clinical/lung mechanics profile of patients with chronic obstructive pulmonary disease (COPD). Twenty patients with COPD were examined on the treadmill at rest and during steady state exercise at the highest workload comfortably tolerable to the subjects (60-70% V˙o2 max). In eight patients, the exercise cardiac output was <80% of predicted, while in the remainder (n = 12), the cardiac output response was normal (>80% of predicted). It was concluded that hyperinflation and severe expiratory airflow limitation may be important determinants of the low exercise cardiac output response in some patients with COPD.

Section snippets

PATIENTS

Twenty patients with COPD were investigated. They had been referred to the clinical laboratory for characterization of their effort intolerance. All patients had evidence of expiratory airflow limitation in that two or more expiratory flow variables were more than 1.65 standard deviations below the value predicted for age, sex, race, and anthropometric habitus.8, 9 Patients with evidence of pulmonary restriction, as gauged by reduced total lung capacity, and/or high recoil (measured from the

METHODS

Lung mechanics were measured from maximal expiratory flow-volume loops using a wedge spirometer. For residual volume measurement, for the estimation of total lung capacity, the single breath nitrogen washout method was used as modified by Bründler and Lewis11 to compensate for underestimation of lung volume due to poor gas mixing. The single-breath CO diffusion capacity (Dco) was measured in 15 subjects using a Morgan Transfer-test Model C linked to a microprocessor. The Dco value was

RESULTS

The mean age of the patients in this study was 54.7±9.3 years. The mean FEV1 was 1.68±0.531, FEV1/FVC 54.8±14.6 percent and the forced expiratory flow at 50 percent of FVC (FEF50) 31.9± 18.4 percent of predicted.8 The FRC/TLC ratio was 111.5 ±29.3 percent of predicted while TLC was 103 ±16.6 percent of predicted.8, 9 The slope of phase III of the single breath nitrogen washout curve varied from 0.30 to 21.95 percent/L (mean value, 6.52±5.66 percent/L). The normalized CO transfer factor (TL/VA)

DISCUSSION

In this study, the patients could be clearly divided into a group whose exercise cardiac output was low and a group in whom it was normal. In the low cardiac output group, there was more severe lung hyperinflation and expiratory airflow limitation at rest, but on exercise, both groups utilized a similar proportion of their ventilatory capacity. Although the mean pulmonary artery pressures were similar both at rest and on exercise, the pulmonary vascular resistance values were very much higher

CONCLUSIONS

Despite the linear relationship between arterial oxygenation (SaO2 and pulmonary artery pressure both at rest and on exercise in patients with COPD, the findings of this study suggest that lung hyperinflation and severe expiratory airflow limitation may be important determinants of the severely elevated pulmonary vascular resistance and the low cardiac output observed in eight of the 20 subjects included in this study.

ACKNOWLEDGMENTS

The authors thank the technologists of the Pulmonary Function Laboratory, Tygerberg Hospital, for their assistance.

REFERENCES (30)

  • MinhVD et al.

    Hypoxemia during exercise in patients with chronic obstructive pulmonary disease

    Am Rev Respir Dis

    (1979)
  • GrimbyS et al.

    Spirometric studies in normal subjects: III: Static lung volumes and maximal voluntary ventilation in adults with a note on physical fitness

    Acta Med Scand

    (1983)
  • BründlerJP et al.

    Functional classification of chronic airflow limitation based on flow-volume and single breath nitrogen washout criteria

    Respiration

    (1983)
  • BründlerJP et al.

    Estimation of lung volume from nitrogen washout curves

    Bull Europ Physiopath Respir

    (1981)
  • CotesJE

    Lung function: assessment and application in medicine

    (1979)
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    Manuscript received May 20; revision accepted July 26.

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