Comparison of spirometric thresholds in diagnosing smoking-related airflow obstruction: authors' response

Effects of dexmedetomidine on oxidative stress and inflammatory response in lungs during mechanical ventilation in COPD rats

Effects of dexmedetomidine (Dex) on oxidative stress and inflammatory response in lungs during mechanical ventilation in chronic obstructive pulmonary disease (COPD) rats were investigated. Eleven out of 38 SD rats were randomly selected as the blank control group, and the other 27 rats were subjected to modeling. After the modeling, 11 rats in the blank control group and 11 rats randomly selected from the model group received non-invasive test for lung function. Three rats from the blank control group and 3 rats from the model group were selected for hematoxylin and eosin (HE) staining to confirm successful modeling, and the other 24 rats were randomly divided into 3 groups, 8 rats in each group, including model control, Dex low-dose and Dex high-dose group. A COPD rat model was established by passive cigarette smoking and intratracheal instillation of lipopolysaccharide. Each group underwent mechanical ventilation for 2 h. The Dex low-dose group and Dex high-dose group were intravenously administered at 1.0 µg/kg/h and 5.0 µg/kg/h of Dex, and the other two groups received intravenous drip of the same amount of normal saline. Blood gas analysis was performed to calculate carbon dioxide partial pressure (PaCO₂), oxygen partial pressure (PaO₂) and blood pH. HE staining was performed to analyze pulmonary pathological features of COPD rat model. Serum inflammatory factors interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA) were detected by ELISA, and the levels of antioxidant enzymes superoxide dismutase 2 (SOD2) and catalase were analyzed by western blot analysis. After 28 days of modeling, TV, PEF, FEV0.3 and FEV0.3/FVC decreased significantly in the COPD model group. HE staining showed that in the model group, the alveolar cells became larger, the alveolar wall became thinner, and some alveolar walls were even broken. The lung lobule showed obvious cell degeneration, necrosis and shedding, and the interstitial inflammatory cell infiltration, suggesting that the COPD rat model was successfully established. After 2 h of mechanical ventilation and Dex intravenous infusion, PaCO₂ decreased, PaO₂ increased, and blood pH value increased (p<0.05). Inflammatory factors IL-8 and TNF-α decreased (p<0.05). Oxidative stress index MDA also decreased (p<0.05), antioxidant enzymes SOD2 and catalase increased (p<0.05). Dexmedetomidine can improve the oxidative stress response during mechanical ventilation in rats with COPD, and can reduce the inflammation of lung tissue, thus protecting the lung tissue of COPD rats.

Clinical characteristics of patients newly diagnosed with COPD by the fixed ratio and lower limit of normal criteria: a cross-sectional analysis of the TargetCOPD trial

Background

Consensus on the definition of airflow obstruction to diagnose COPD remains unresolved.

Methods

We undertook systematic case finding for COPD in primary care using the fixed ratio (FR) criterion (forced expiratory volume in 1 s/forced vital capacity [FEV1/FVC] <0.7) for defining airflow obstruction and also using the lower limit of normal (LLN). We then compared the clinical characteristics of those identified by the 2 criteria.

Results

A total of 3,721 individuals reporting respiratory symptoms were invited for spirometry. A total of 2,607 attended (mean age 60.4 years, 52.8% male, 29.8% current smokers) and 32.6% had airflow obstruction by FR ("FR+") and 20.2% by LLN ("LLN+"). Compared with the LLN+/FR+ group, the LLN-/FR+ group (12.4%) was significantly older, had higher FEV1 and FEV1/FVC, lower COPD assessment test scores, and less cough, sputum, and wheeze, but was significantly more likely to report a diagnosis of heart disease (14.2% versus 6.9%, p<0.001). Compared with the LLN+/FR+ group, the LLN-/FR- group was younger, had a higher body mass index, fewer pack-years, a lower prevalence of respiratory symptoms except for dyspnea, and lower FVC and higher FEV1. The probability of known heart disease was significantly lower in the LLN+/FR+ group compared with those with preserved lung function (LLN-/FR-) (adjusted odds ratio 0.62, 95% CI: 0.43-0.90) but this was not seen in the LLN-/FR+ group (adjusted odds ratio 0.90, 95% CI: 0.63-1.29).

Conclusion

In symptomatic individuals, defining airflow obstruction by FR instead of LLN identifies a significant number of individuals who have less respiratory and more cardiac clinical characteristics.

Breakdown of lung framework and an increase in pores of Kohn as initial events of emphysema and a cause of reduction in diffusing capacity

Purpose

Pulmonary emphysema is the pathological prototype of chronic obstructive pulmonary disease and is also associated with other lung diseases. We considered that observation with different approaches may provide new insights for the pathogenesis of emphysema.

Patients and methods

We reviewed tissue blocks of the lungs of 25 cases with/without emphysema and applied a three-dimensional observation method to the blocks. Based on the three-dimensional characteristics of the alveolar structure, we considered one face of the alveolar polyhedron as a structural unit of alveoli and called it a framework unit (FU). We categorized FUs based on their morphological characteristics and counted their number to evaluate the destructive changes in alveoli. We also evaluated the number and the area of pores of Kohn in FUs. We performed linear regression analysis to estimate the effect of these data on pulmonary function tests.

Results

In multivariable regression analysis, a decrease in the number of FUs without an alveolar wall led to a significant decrease in the diffusing capacity of the lung for carbon monoxide (DLCO) and DLCO per unit alveolar volume, and an increase in the area of pores of Kohn had a significant effect on an increase in residual capacity.

Conclusion

A breakdown in the lung framework and an increase in pores of Kohn are associated with a decrease in DLCO and DLCO per unit alveolar volume with/without emphysema.

Developing and Implementing Biomarkers and Novel Imaging in COPD

This article serves as a CME available, enduring material summary of the following COPD9_USA presentations: "Computed Tomography and COPD" Presenter: George R. Washko, MD "CT Imaging in Routine Clinical Practice: Are We Ready for Prime Time?" Presenter: Meilan K. Han, MD "Beyond CT: What MRI can Tell Us about COPD" Presenter: R. Graham Barr, MD.