TY - JOUR
T1 - Not ALL measures of hyperinflation are created equal
T2 - Lung structure and clinical correlates of gas trapping and hyperexpansion in COPD: the Multi-Ethnic Study of Atherosclerosis (MESA) COPD study
AU - Smith, Benjamin M.
AU - Hoffman, Eric A.
AU - Basner, Robert C.
AU - Kawut, Steven M.
AU - Kalhan, Ravi
AU - Graham Barr, R.
N1 - Funding Information:
Funding/Support: This study was funded by the National Institutes of Health, National Heart, Lung, and Blood Institute [Grants R01-HL093081, R01-HL077612, and R01-HL075476; Contracts N01 HC 95159 through N01 HC 95165 and N01 HC 95169] and Fonds de la recherche en santé Québec.
Funding Information:
Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Smith is funded by the Fonds de la recherche en santé Québec. Dr Hoffman holds grants from the National Institutes of Health (NIH), Alpha-1 Foundation, and American Lung Foundation and is a founder of and shareholder in VIDA Diagnostics, Inc. Dr Basner holds grants from NIH and has received royalties from UpToDate, Inc. Dr Kawut holds grants from NIH. Dr Kalhan holds grants from NIH; has received royalties from UpToDate, Inc; and has consulted for Boehringer Ingelheim GmbH; Forest Laboratories, Inc; and Sunovion Pharmaceuticals Inc (formerly Elevation Pharmaceuticals). Dr Barr holds grants from NIH, Alpha-1 Foundation, and the US Environmental Protection Agency and has received royalties from UpToDate, Inc.
PY - 2014/6
Y1 - 2014/6
N2 - Background: Hyperinflation refers to a nonspecific increase in absolute lung volumes and has a poor prognosis in COPD. The relative contribution of increased airways resistance and increased parenchymal compliance to hyperinflation of each absolute lung volume is poorly understood. We hypothesized that increased residual volume (RV) and RV/total lung capacity (TLC) would be associated with reduced airway lumen dimensions, whereas increased functional residual capacity (FRC), TLC, and reduced inspiratory capacity (IC)/TLC would be associated with emphysema on CT scan. We examined whether clinical characteristics differed accordingly. Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited smokers aged 50 to 79 years who were free of clinical cardiovascular disease. Gas trapping was defined as RV or RV/TLC greater than the upper limit of normal and hyperexpansion as FRC or TLC greater than the upper limit of normal or IC/TLC less than the lower limit of normal. Airway lumen diameters and percent emphysema < -950 Hounsfield units were quantified on CT images. Analyses were adjusted for age, sex, body size, race/ethnicity, education, and smoking. Results: Among 116 participants completing plethysmography, 15% had gas trapping, 18% has hyperexpansion, and 22% had both. Gas trapping was associated with smaller airway lumen diameters (P = .001), greater dyspnea (P = .01), and chronic bronchitis (P = .03). Hyperexpansion was associated with percent emphysema (P<.001), lower BMI (P = .04), and higher hemoglobin concentration (P = .001). Conclusions: Gas trapping and hyperexpansion on plethysmography were associated with distinct differences in lung structure and clinical characteristics. Absolute lung volumes should not be considered equivalent in their estimation of hyperinflation and provide insight into the extent of airway and parenchymal abnormalities in COPD.
AB - Background: Hyperinflation refers to a nonspecific increase in absolute lung volumes and has a poor prognosis in COPD. The relative contribution of increased airways resistance and increased parenchymal compliance to hyperinflation of each absolute lung volume is poorly understood. We hypothesized that increased residual volume (RV) and RV/total lung capacity (TLC) would be associated with reduced airway lumen dimensions, whereas increased functional residual capacity (FRC), TLC, and reduced inspiratory capacity (IC)/TLC would be associated with emphysema on CT scan. We examined whether clinical characteristics differed accordingly. Methods: The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited smokers aged 50 to 79 years who were free of clinical cardiovascular disease. Gas trapping was defined as RV or RV/TLC greater than the upper limit of normal and hyperexpansion as FRC or TLC greater than the upper limit of normal or IC/TLC less than the lower limit of normal. Airway lumen diameters and percent emphysema < -950 Hounsfield units were quantified on CT images. Analyses were adjusted for age, sex, body size, race/ethnicity, education, and smoking. Results: Among 116 participants completing plethysmography, 15% had gas trapping, 18% has hyperexpansion, and 22% had both. Gas trapping was associated with smaller airway lumen diameters (P = .001), greater dyspnea (P = .01), and chronic bronchitis (P = .03). Hyperexpansion was associated with percent emphysema (P<.001), lower BMI (P = .04), and higher hemoglobin concentration (P = .001). Conclusions: Gas trapping and hyperexpansion on plethysmography were associated with distinct differences in lung structure and clinical characteristics. Absolute lung volumes should not be considered equivalent in their estimation of hyperinflation and provide insight into the extent of airway and parenchymal abnormalities in COPD.
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U2 - 10.1378/chest.13-1884
DO - 10.1378/chest.13-1884
M3 - Article
C2 - 24481056
AN - SCOPUS:84901839100
SN - 0012-3692
VL - 145
SP - 1305
EP - 1315
JO - CHEST
JF - CHEST
IS - 6
ER -
