title: Gas exchange alterations in patients with chronic obstructive lung disease.
abstract: In a series of 23 patients with COPD, Wagner et al showed three distinct patterns of VA/Q distributions and a correlation between Burrows' clinical classification and the observed distribution patterns. Using the inert gas method, we studied 51 patients suffering from severe but stable COPD (FEV1 = 0.84 +/- 0.38 L; PaO2 = 58.5 +/- 10.5 mm Hg; PaCo2 = 48 +/- 6 mmHg; Ppa = 22 +/- 8 mmHg) breathing room air in a steady state. The H pattern (high mode of VA in high VA/Q) was found in 24 cases. There was an L pattern (Q mode in low VA/Q units) in nine cases and an HL (high-low) pattern in 16 cases (two patients were assigned another group). The analysis of the distribution data confirmed that VA/Q heterogeneity was the main factor underlying gas exchange disturbances in COPD. The PaO2 of the H subjects was higher than that of both HL (p less than 0.02) and L subjects. The true shunt value in the L group was significantly lower than in the H and HL groups. However, the relationship between clinical or functional aspects and distribution was not direct. The fraction of patients of H, HL, or (H + HL) types was nearly identical in the three clinical groups. The H pattern was found to be predominant in cases of COPD.
mesh_terms: D000368:Aged; D001794:Blood Pressure; D005541:Forced Expiratory Volume; D006439:Hemodynamics; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000097:blood / Q000503:physiopathology*; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011379:Prognosis; D011651:Pulmonary Artery / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D011669:Pulmonary Wedge Pressure; D012126:Respiratory Dead Space; D013147:Spirometry; D014655:Vascular Resistance; D014692:Ventilation-Perfusion Ratio; D014797:Vital Capacity
chemical_list: D010100:Oxygen