title: Non-invasive ultrasonic cardiac output monitoring in exercise testing.
abstract: BACKGROUND
  The purpose of this study was to evaluate the relationship of breath-by-breath oxygen uptake (VO(2)) and CO, cardiac index (CI), stroke volume (SV) and heart rate (HR) determined by a non-invasive continuous wave (CW) Doppler-based system (USCOM) in healthy adolescent and adult athletes during exercise treadmill testing.
  
  
  METHODS
  Twenty athletes were enrolled for a standardized ramp treadmill test including transthoracic echocardiography at rest, incremental breath-by-breath spiroergometry, lactate kinetics and CW Doppler.
  
  
  RESULTS
  VO(2) max was 51+/-11 ml/min/kg in the adolescent cross country skiers (CI 8.2+/-1.2 l/min/m(2)) and 50+/-12 ml/min/kg in adult soccer referees (CI 7.1+/-1.2 l/min/m(2)). CW Doppler hemodynamic variables showed significant correlation with VO(2) (p<0.01, n=95) across the total of measures, with excellent correlation demonstrated for CO and CI (0.904 and 0.897), while HR and SV showed good to very good correlation with r values of 0.842 and 0.766, respectively. Correlation of the variables at peak exercise and 1 and 3 min after recovery, demonstrate that CO and SV show superior correlation with peak oxygen consumption (VO(2) max). The regression equation for VO(2) and CO(USCOM) was VO(2)=4.43CO(USCOM)-10.3.
  
  
  CONCLUSIONS
  CW Doppler measurement of cardiac output is feasible as a measure of cardiac performance during standardized treadmill testing in adolescent and adult athletes.
authors.forename: Karsten
authors.initials: K
authors.lastname: Knobloch
authors.forename: Volker
authors.initials: V
authors.lastname: Hoeltke
authors.forename: Ernst
authors.initials: E
authors.lastname: Jakob
authors.forename: Peter M
authors.initials: PM
authors.lastname: Vogt
authors.forename: Rob
authors.initials: R
authors.lastname: Phillips
mesh_terms: D000293:Adolescent; D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism; D002302:Cardiac Output / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D010101:Oxygen Consumption / Q000502:physiology; D011336:Probability; D012016:Reference Values; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013177:Sports; D013318:Stroke Volume / Q000502:physiology*; D018608:Ultrasonography, Doppler / Q000379:methods*
chemical_list: D002245:Carbon Dioxide