A comparison of single breath and re-breathe diffusing capacity in emphysema patients and controls.
In emphysema patients, gas dilutional alveolar volume is underestimated by a 10s single breath maneuver at total lung capacity (TLC) compared with re-breathing at functional residual capacity (FRC); corresponding underestimation of single breath diffusing capacity (DLCO) in emphysema has not been demonstrated. The purpose of this study was to quantify the degree to which re-breathe DLCO at FRC (DLCO(RB)) differs from single breath DLCO at TLC (DLCO(SB)) in emphysema. In 37 consecutively recruited patients with moderate to severe emphysema (FEV1/FVC 40%±10% predicted), DLCO(RB) as % predicted of 91 controls without cardiopulmonary disease was 79%±24%, significantly greater than % predicted DLCO(SB) (44%±19%; p<0.0001). DLCO(RB)/DLCO(SB) was inversely proportional to FEV1% predicted (R = -0.47, p=0.004), and FEV1/FVC (R = -0.54, p<0.001). These data indicate that a 10s single breath DLCO maneuver progressively under-represents re-breathe lung diffusing capacity in emphysema as airflow obstruction increases.
Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Jeremy A
JA
Weingarten
David J
DJ
Lederer
Erkan
E
Ozturk
Fulvia M
FM
Milite
Anne M
AM
Mooney
Byron M
BM
Thomashow
Robert C
RC
Basner
D000328:Adult; D004646:Emphysema / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity / Q000379:methods*; D012119:Respiration