Ventilation-perfusion imbalance and chronic obstructive pulmonary disease staging severity

Abstract

Chronic obstructive pulmonary disease (COPD) is characterized by a decline in forced expiratory volume in 1 s (FEV(1)) and, in many advanced patients, by arterial hypoxemia with or without hypercapnia. Spirometric and gas exchange abnormalities have not been found to relate closely, but this may reflect a narrow range of severity in patients studied. Therefore, we assessed the relationship between pulmonary gas exchange and airflow limitation in patients with COPD across the severity spectrum. Ventilation-perfusion (V(A)/Q) mismatch was measured using the multiple inert gas elimination technique in 150 patients from previous studies. The distribution of patients according to the GOLD stage of COPD was: 15 with stage 1; 40 with stage 2; 32 with stage 3; and 63 with stage 4. In GOLD stage 1, AaPo(2) and V(A)/Q mismatch were clearly abnormal; thereafter, hypoxemia, AaPo(2), and V(A)/Q imbalance increased, but the changes from GOLD stages 1-4 were modest. Postbronchodilator FEV(1) was related to Pa(O(2)) (r = 0.62) and Pa(CO(2)) (r = -0.59) and to overall V(A)/Q heterogeneity (r = -0.48) (P < 0.001 each). Pulmonary gas exchange abnormalities in COPD are related to FEV(1) across the spectrum of severity. V(A)/Q imbalance, predominantly perfusion heterogeneity, is disproportionately greater than airflow limitation in GOLD stage 1, suggesting that COPD initially involves the smallest airways, parenchyma, and pulmonary vessels with minimal spirometric disturbances. That progression of V(A)/Q inequality with spirometric severity is modest may reflect pathogenic processes that reduce both local ventilation and blood flow in the same regions through airway and alveolar disease and capillary involvement.

Detection of Lung Dysfunction Using Ventilation and Perfusion SPECT in a Mouse Model of Chronic Cigarette Smoke Exposure

“…The CS exposure model caused significant neutrophilia and monocyte infiltration whereas only a slight increase in airspace enlargement was observed after 24 wk. The V/Q profile observed in this context is consistent with clinical MIGET data in which V/Q mismatch was observed in GOLD stage I (9). MIGET studies have also provided evidence that high V/Q values tend to be present in patients with emphysematous pathology whereas low V/Q values tend to be present in patients with greater inflammatory indices and small-airway pathology (24,25).…”

“…Clinical methods that measure ventilation/perfusion (V/Q) ratios in the lung have been shown to have high sensitivity to COPD pathologies, as demonstrated by Rodríguez-Roisin et al using the multiple inert gas elimination technique (MIGET) (9). Although this methodology is well suited to understanding respiratory disease mechanisms because of its ability to describe the distribution of V/Q ratios in the lung, it lacks the ability to spatially distinguish underlying pathologies (10) and is not readily available in clinical practice.…”

Lung Hyperinflation and Its Reversibility in Patients with Airway Obstruction of Varying Severity

“…D LCO measurements were lower than in the healthy control group but varied widely. We could not control for the potential effects of active tobacco smoking (33). However, the finding that approximately 20% of the GOLD I subgroup had a D LCO <70%predicted suggests that the surface area for gas exchange was abnormal in some.…”

Contemporary Approaches to the Chronic Obstructive Pulmonary Disease Exacerbations in Emergency Department

“…Alveoler ventilasyondaki bu anormallikler ve pulmoner vasküler yatakta azalma, ventilasyon/perfüzyon oranın-daki anormalliğin daha da kötüleşmesine neden olmaktadır. 9 Özellikle alevlenmede daha belirgin olmak üzere TNF-α, IL-1β ve IL-6 gibi enflamatuar sitokinlerin etkisi ile; CRP, fibrinojen, serum amiloid A ve sürfaktan protein D gibi akut faz proteinlerinde artış olmaktadır.…”