Dynamic hyperinflation is associated with a poor cardiovascular response to exercise in COPD patientsReport as inadecuate




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Respiratory Research

, 12:150

First Online: 01 December 2011Received: 19 July 2011Accepted: 10 November 2011

Abstract

BackgroundPulmonary 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.

MethodsWe 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.

ResultsPatients 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.

ConclusionThe 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.

Keywordsdynamic hyperinflation cardiovascular response exercise COPD AbbreviationsACEangiotensin converting enzyme

BMIbody mass index

COPDchronic obstructive pulmonary disease

CPETcardiopulmonary exercise test

DPdouble product

EELVend-expiratory lung volume

FEV1forced expiratory volume in 1 second

FEF50forced expiratory flow at 50% of FVC

FIF50forced inspiratory flow at 50% of FVC

FVCforced vital capacity

HRheart rate

ICinspiratory capacity

MWmaximal workload

O2pulseoxygen pulse

OUESoxygen uptake efficiency slope

RERrespiratory exchange ratio

ROCreceiver operating characteristic

SpO2oxygen saturation

SDstandard deviation

TGVthoracic gas volume

TLCtotal lung capacity

TLcolung diffusion capacity for carbon monoxide

VASvisual analogue scale

VCvital capacity

VCO2carbon dioxide production

VEventilation

VO2oxygen uptake.

Electronic supplementary materialThe online version of this article doi:10.1186-1465-9921-12-150 contains supplementary material, which is available to authorized users.

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