title: Dynamic hyperinflation is associated with a poor cardiovascular response to exercise in COPD patients.
abstract: BACKGROUND
  Pulmonary hyperinflation has the potential for significant adverse effects on cardiovascular function in COPD. The aim of this study was to investigate the relationship between dynamic hyperinflation and cardiovascular response to maximal exercise in COPD patients.
  
  
  METHODS
  We studied 48 patients (16F; age 68 yrs ± 8; BMI 26 ± 4) with COPD. All patients performed spirometry, plethysmography, lung diffusion capacity for carbon monoxide (TLco) measurement, and symptom-limited cardiopulmonary exercise test (CPET). The end-expiratory lung volume (EELV) was evaluated during the CPET. Cardiovascular response was assessed by change during exercise in oxygen pulse (ΔO2Pulse) and double product, i.e. the product of systolic blood pressure and heart rate (DP reserve), and by the oxygen uptake efficiency slope (OUES), i.e. the relation between oxygen uptake and ventilation.
  
  
  RESULTS
  Patients with a peak exercise EELV (%TLC) ≥ 75% had a significantly lower resting FEV1/VC, FEF50/FIF50 ratio and IC/TLC ratio, when compared to patients with a peak exercise EELV (%TLC) < 75%. Dynamic hyperinflation was strictly associated to a poor cardiovascular response to exercise: EELV (%TLC) showed a negative correlation with ΔO2Pulse (r = - 0.476, p = 0.001), OUES (r = - 0.452, p = 0.001) and DP reserve (r = - 0.425, p = 0.004). Furthermore, according to the ROC curve method, ΔO2Pulse and DP reserve cut-off points which maximized sensitivity and specificity, with respect to a EELV (% TLC) value ≥ 75% as a threshold value, were ≤ 5.5 mL/bpm (0.640 sensitivity and 0.696 specificity) and ≤ 10,000 Hg · bpm (0.720 sensitivity and 0.783 specificity), respectively.
  
  
  CONCLUSIONS
  The present study shows that COPD patients with dynamic hyperinflation have a poor cardiovascular response to exercise. This finding supports the view that in COPD patients, dynamic hyperinflation may affect exercise performance not only by affecting ventilation, but also cardiac function.
authors.affiliation: Cardiopulmonary Dept, Lung Function Unit, University Hospital (via Rasori 10), Parma (43125), Italy. panayotat@yahoo.com
authors.forename: Panagiota
authors.initials: P
authors.lastname: Tzani
authors.forename: Marina
authors.initials: M
authors.lastname: Aiello
authors.forename: Davide
authors.initials: D
authors.lastname: Elia
authors.forename: Luca
authors.initials: L
authors.lastname: Boracchia
authors.forename: Emilio
authors.initials: E
authors.lastname: Marangio
authors.forename: Dario
authors.initials: D
authors.lastname: Olivieri
authors.forename: Enrico
authors.initials: E
authors.lastname: Clini
authors.forename: Alfredo
authors.initials: A
authors.lastname: Chetta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D002000:Bronchospirometry / Q000009:adverse effects; D005080:Exercise Test / Q000009:adverse effects / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010991:Plethysmography / Q000009:adverse effects; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*
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