Silent Airway Mucus Plugs in COPD and Clinical Implications

BACKGROUND

Airway mucus plugs are frequently identified on CT scans of patients with COPD with a smoking history without mucus-related symptoms (ie, cough, phlegm [silent mucus plugs]).

RESEARCH QUESTION

In patients with COPD, what are the risk and protective factors associated with silent airway mucus plugs? Are silent mucus plugs associated with functional, structural, and clinical measures of disease?

STUDY DESIGN AND METHODS

We identified mucus plugs on chest CT scans of participants with COPD from the COPDGene study. The mucus plug score was defined as the number of pulmonary segments with mucus plugs, ranging from 0 to 18, and categorized into three groups (0, 1-2, and ≥ 3). We determined risk and protective factors for silent mucus plugs and the associations of silent mucus plugs with measures of disease severity using multivariable linear and logistic regression models.

RESULTS

Of 4,363 participants with COPD, 1,739 had no cough or phlegm. Among the 1,739 participants, 627 (36%) had airway mucus plugs identified on CT scan. Risk factors of silent mucus plugs (compared with symptomatic mucus plugs) were older age (OR, 1.02), female sex (OR, 1.40), and Black race (OR, 1.93) (all P values < .01). Among those without cough or phlegm, silent mucus plugs (vs absence of mucus plugs) were associated with worse 6-min walk distance, worse resting arterial oxygen saturation, worse FEV1 % predicted, greater emphysema, thicker airway walls, and higher odds of severe exacerbation in the past year in adjusted models.

INTERPRETATION

Mucus plugs are common in patients with COPD without mucus-related symptoms. Silent mucus plugs are associated with worse functional, structural, and clinical measures of disease. CT scan-identified mucus plugs can complement the evaluation of patients with COPD.

Airway-Occluding Mucus Plugs and Mortality in Patients With Chronic Obstructive Pulmonary Disease

Importance

Airway mucus plugs are common in patients with chronic obstructive pulmonary disease (COPD); however, the association of airway mucus plugging and mortality in patients with COPD is unknown.

Objective

To determine whether airway mucus plugs identified on chest computed tomography (CT) were associated with increased all-cause mortality.

Design, Setting, and Participants

Observational retrospective analysis of prospectively collected data of patients with a diagnosis of COPD in the Genetic Epidemiology of COPD cohort. Participants were non-Hispanic Black or White individuals, aged 45 to 80 years, who smoked at least 10 pack-years. Participants were enrolled at 21 centers across the US between November 2007 and April 2011 and were followed up through August 31, 2022.

Exposures

Mucus plugs that completely occluded airways on chest CT scans, identified in medium- to large-sized airways (ie, approximately 2- to 10-mm lumen diameter) and categorized as affecting 0, 1 to 2, or 3 or more lung segments.

Main Outcomes and Measures

The primary outcome was all-cause mortality, assessed with proportional hazard regression analysis. Models were adjusted for age, sex, race and ethnicity, body mass index, pack-years smoked, current smoking status, forced expiratory volume in the first second of expiration, and CT measures of emphysema and airway disease.

Results

Among the 4483 participants with COPD, 4363 were included in the primary analysis (median age, 63 years [IQR, 57-70 years]; 44% were women). A total of 2585 (59.3%), 953 (21.8%), and 825 (18.9%) participants had mucus plugs in 0, 1 to 2, and 3 or more lung segments, respectively. During a median 9.5-year follow-up, 1769 participants (40.6%) died. The mortality rates were 34.0% (95% CI, 32.2%-35.8%), 46.7% (95% CI, 43.5%-49.9%), and 54.1% (95% CI, 50.7%-57.4%) in participants who had mucus plugs in 0, 1 to 2, and 3 or more lung segments, respectively. The presence of mucus plugs in 1 to 2 vs 0 and 3 or more vs 0 lung segments was associated with an adjusted hazard ratio of death of 1.15 (95% CI, 1.02-1.29) and 1.24 (95% CI, 1.10-1.41), respectively.

Conclusions and Relevance

In participants with COPD, the presence of mucus plugs that obstructed medium- to large-sized airways was associated with higher all-cause mortality compared with patients without mucus plugging on chest CT scans.

Adult Partial Anomalous Pulmonary Venous Return Repair and Superior Vena Cava Syndrome: A Delayed Complication of the Warden Procedure

The Warden procedure is one of the most common techniques for surgical correction of partial anomalous pulmonary venous return (PAPVR), involving transection and reanastomosis of the superior vena cava (SVC) to the right atrial appendage and baffling of the anomalous pulmonary veins through the atrial septal defect. While the procedure is typically well-tolerated in pediatric patients, adult patients requiring surgical correction of PAPVR are uncommon. The authors report a case of a 33-year-old woman who developed SVC syndrome as a delayed complication of the Warden procedure. Keywords: Cardiac, Congenital, Complications © RSNA, 2022.

Review of pericardial disease on computed tomography

Echocardiography has long been the mainstay in the evaluation of cardiac and pericardial disease. As computed tomography (CT) has advanced, it has become a valuable partner in the imaging of the pericardium. The advantages of CT include a larger field of view, multiplanar reconstruction and increased discrimination between various soft tissues and fluids. CT is less operator dependent and can more easily, and reproducibly, image areas of the pericardium for which echocardiography has poor windows such as the right pericardium. The introduction of EKG gating has decreased cardiac motion artifact and can allow functional evaluation although echocardiography remains the primary source of real-time imaging of cardiac and valve motion. It is essential for the skilled cardiac imager to understand the strengths and weaknesses of CT and its role in the definition and assessment of pericardial disease.

Cardiac computed tomographic evaluation of coronary artery calcification: A review

Vascular calcification is most commonly due to atherosclerosis. It has been well documented that absence of coronary calcification on a chest CT (CCT) is associated with low cardiovascular events and good prognosis. High CT calcium scores often result in a higher incidence of cardiovascular events and worse survival. In asymptomatic patients with an intermediate risk for coronary artery disease, numerous studies have shown Coronary Calcium Scoring (CCS) has prognostic relevance and incremental prognostic value over conventional risk stratification. CT detected calcium score plays important role in patient management. This article will review various CT based coronary artery calcium scoring methods.

Utility of Scintigraphy in Assessment of Noninfectious Complications of Peritoneal Dialysis

Dialysis is an artificial process to remove waste products and excess water from the body in patients with kidney failure. Two main types of dialysis are available. Hemodialysis, which uses an artificial filtration apparatus, is usually done at specialized centers but can be done in a patient's home. Peritoneal dialysis functions by placing dialysis fluid, also called dialysate, into the peritoneal cavity, allowing for solute to be removed from the peritoneal capillaries through diffusion across a chemical gradient into the dialysate and removal of water through an osmotic gradient created by hypertonic dextrose. Peritoneal dialysis can be either automated, which is done with the help of a machine called a cycler, or continuous ambulatory, which is a process involving multiple exchanges a day and is performed using only gravity to infuse and drain the solution from the peritoneal cavity. For many reasons, the number of people using home dialysis has recently started to rise, with the largest increase in the United States occurring after the implementation of the prospective bundled payment system for end-stage renal disease. With the increased use of home dialysis, potential complications will increase as well. It is imperative that our health-care system be poised not only to increase the number of home dialysis patients but also to diagnose and manage any complications. Nuclear imaging is a commonly available modality to detect various complications related to peritoneal dialysis. In this review article, we discuss the role of peritoneal scintigraphy in detecting some noninfectious peritoneal dialysis complications, with emphasis on scintigraphy technique; imaging time points; the role of planar, SPECT, and SPECT/CT imaging; and the clinical indications, with illustrative case examples.

Loss of INK4a/Arf gene enhances ultraviolet radiation-induced cutaneous tumor development

The CDKN2A locus encodes for tumor suppressor genes p16^INK4a and p14^Arf which are frequently inactivated in human skin tumors. The purpose of this study was to determine the relationship between loss of INK4a/Arf activity and inflammation in the development of ultraviolet (UV) radiation-induced skin tumors. Panels of INK4a/Arf^-/- mice and wild-type (WT) mice were treated with a single dose of UVB (200 mJ/cm² ). For long-term studies, these mice were irradiated with UVB (200 mJ/cm² ) three times weekly for 30 weeks. At the end of the experiment, tissues were harvested from mice and assayed for inflammatory biomarkers and cytokines. A single dose of UVB resulted in a significant increase in reactive oxygen species (ROS) and 8-dihydroxyguanosine (8-oxo-dG) lesions in INK4a/Arf^-/- mice compared to WT mice. When subjected to chronic UVB, we found that 100% of INK4a/Arf^-/- mice had tumors, whereas there were no tumors in WT controls after 24 weeks of UVB exposure. The increase in tumor development correlated with a significant increase in nuclear factor (NF)-κB, cyclooxygenase-2 (COX-2), prostaglandin E₂ (PGE₂ ) and its receptors both in UVB-exposed skin and in the tumors. A significant increase was seen in inflammatory cytokines in skin samples of INK4a/Arf^-/- mice following treatment with chronic UVB radiation. Furthermore, significantly more CD11b⁺ Gr1⁺ myeloid cells were present in UVB-exposed INK4a/Arf^-/- mice compared to WT mice. Our data indicate that by targeting UVB-induced inflammation, it may be possible to prevent UVB-induced skin tumors in individuals that carry CDKN2A mutation.