Kristin M. Burkart

Genome-Wide Association Studies Identify CHRNA5/3 and HTR4 in the Development of Airflow Obstruction

RATIONALE Genome-wide association studies (GWAS) have identified loci influencing lung function, but fewer genes influencing chronic obstructive pulmonary disease (COPD) are known. OBJECTIVES Perform meta-analyses of GWAS for airflow obstruction, a key pathophysiologic characteristic of COPD assessed by spirometry, in population-based cohorts examining all participants, ever smokers, never smokers, asthma-free participants, and more severe cases. METHODS Fifteen cohorts were studied for discovery (3,368 affected; 29,507 unaffected), and a population-based family study and a meta-analysis of case-control studies were used for replication and regional follow-up (3,837 cases; 4,479 control subjects). Airflow obstruction was defined as FEV(1) and its ratio to FVC (FEV(1)/FVC) both less than their respective lower limits of normal as determined by published reference equations. MEASUREMENTS AND MAIN RESULTS The discovery meta-analyses identified one region on chromosome 15q25.1 meeting genome-wide significance in ever smokers that includes AGPHD1, IREB2, and CHRNA5/CHRNA3 genes. The region was also modestly associated among never smokers. Gene expression studies confirmed the presence of CHRNA5/3 in lung, airway smooth muscle, and bronchial epithelial cells. A single-nucleotide polymorphism in HTR4, a gene previously related to FEV(1)/FVC, achieved genome-wide statistical significance in combined meta-analysis. Top single-nucleotide polymorphisms in ADAM19, RARB, PPAP2B, and ADAMTS19 were nominally replicated in the COPD meta-analysis. CONCLUSIONS These results suggest an important role for the CHRNA5/3 region as a genetic risk factor for airflow obstruction that may be independent of smoking and implicate the HTR4 gene in the etiology of airflow obstruction.

Pilot Study of Extracorporeal Carbon Dioxide Removal to Facilitate Extubation and Ambulation in Exacerbations of Chronic Obstructive Pulmonary Disease

RATIONALE Acute exacerbations of chronic obstructive pulmonary disease (COPD) requiring invasive mechanical ventilation (IMV) are associated with significant morbidity and mortality. Extracorporeal carbon dioxide removal (ECCO₂R) may facilitate extubation and ambulation in these patients and potentially improve outcomes. OBJECTIVES We assessed the feasibility of achieving early extubation and ambulation in subjects requiring IMV for exacerbations of COPD using single-site ECCO₂R. METHODS Five subjects with exacerbations of COPD with uncompensated hypercapnia requiring IMV were enrolled in this single-center, prospective, feasibility trial using a protocol of ECCO₂R, extubation, and physical rehabilitation. The primary endpoint was extubation within 72 hours of starting ECCO₂R. MEASUREMENTS AND MAIN RESULTS Mean preintubation pH and PaCO₂ were 7.23 ± 0.05 and 81.6 ± 15.9 mm Hg, respectively. All subjects met the primary endpoint (median duration, 4 h; range, 1.5-21.5 h). Mean duration of extracorporeal support was 193.0 ± 76.5 hours. Mean time to ambulation after extracorporeal initiation was 29.4 ± 12.6 hours. Mean maximal ambulation on extracorporeal support was 302 feet (range, 70-600). Four subjects were discharged home, and one underwent planned lung transplantation. Two minor bleeding complications occurred. There were no complications from mobilization on extracorporeal support. CONCLUSIONS ECCO₂R facilitates early extubation and ambulation in exacerbations of COPD requiring IMV and has the potential to serve as a new paradigm for the management of a select group of patients. Rigorous clinical trials are needed to corroborate these results and to investigate the effect on long-term outcomes and cost effectiveness over conventional management.

Upper-body extracorporeal membrane oxygenation as a strategy in decompensated pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a disease with significant morbidity and mortality, particularly during an acute decompensation. We describe a single-center experience of three patients with severe Group 1 PAH, refractory to targeted medical therapy, in which an extubated, nonsedated, extracorporeal membrane oxygenation (ECMO) strategy with an upper-body configuration was used as a bridge to recovery or lung transplantation. All three patients were extubated within 24 hours of ECMO initiation. Two patients were successfully bridged to lung transplantation, and the other patient was optimized on targeted PAH therapy with subsequent recovery from an acute decompensation. The upper-body ECMO configuration allowed for daily physical therapy, including one patient, who would otherwise have been unsuitable for transplantation, ambulating over 850 meters daily. This series demonstrates the feasibility of using ECMO to bridge PAH patients to recovery or transplantation while avoiding the complications of immobility and invasive mechanical ventilation.

Blood Conservation in Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome

BACKGROUND Extracorporeal membrane oxygenation support (ECMO) typically requires multiple blood transfusions and is associated with frequent bleeding complications. Blood transfusions are known to increase morbidity and mortality in critically ill patients, which may extend to patients receiving ECMO. Aiming to reduce transfusion requirements, we implemented a blood conservation protocol in adults with severe acute respiratory distress syndrome (ARDS) receiving ECMO. METHODS This was a retrospective study of adults receiving ECMO for ARDS after initiation of a blood conservation protocol that included a transfusion trigger of hemoglobin of less than 7.0 g/dL, use of low-dose anticoagulation targeting an activated partial thromboplastin time of 40 to 60 seconds, and autotransfusion of circuit blood during decannulation. The primary objective was to evaluate transfusion requirements during ECMO support. Clinical outcomes included survival, neurologic function, renal function, bleeding, and thrombotic complications. RESULTS The analysis included 38 patients; of these, 24 (63.2%) received a transfusion while receiving ECMO. Median hemoglobin was 8.29 g/dL. A median of 1.0 units (range, 250 to 300 mL) was transfused during ECMO support over a median duration of 9.0 days, equivalent to 0.11 U/d (range, 27.5 to 33.3 mL/d). The median activated partial thromboplastin time was 46.5 seconds. Bleeding occurred in 10 patients (26.3%); severe bleeding occurred in 2 patients (5.3%). Twenty-eight patients (73.7%) survived to hospital discharge. CONCLUSIONS Implementation of a blood conservation protocol in adults receiving ECMO for ARDS resulted in lower transfusion requirements and bleeding complications than previously reported in the literature and was associated with comparable survival and organ recovery.

Opportunities and Challenges in the Genetics of COPD 2010: An International COPD Genetics Conference Report

Chronic obstructive pulmonary disease (COPD) is defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as a disease state characterized by airflow limitation that is not fully reversible (1). Cigarette smoking is the most important risk factor for the development of COPD. Although the dose-response relationship between cigarette smoking and pulmonary function is well-established, there is considerable variability in the reduction in FEV1 among smokers with similar smoking exposures (2, 3). The low percentage of variance in pulmonary function explained by smoking suggests that there could be genetic differences in susceptibility to the effects of cigarette smoking (4, 5). In addition to genetic factors, other environmental determinants such as indoor biomass smoke exposure can be important risk factors for COPD (6). A small percentage of COPD patients (estimated at 1-2%) inherit severe alpha-1 antitrypsin (AAT) deficiency, which proves that genetic factors can in-fluence COPD susceptibility. The discovery of AAT deficiency was a major factor in the development of the Protease-Antiprotease Hypothesis for COPD, which has been one of the prevailing models of disease pathogenesis for more than 40 years. With the substantial impact of AAT deficiency on our understanding of COPD pathogenesis, it was natural to hope that the identification of other COPD susceptibility genes would lead to similar novel insights into COPD. Until recently, however, progress in the identification of additional genetic risk factors for COPD has been slow. To facilitate the development of such research, a meeting of COPD genetics investigators was held on July 13-14,2010 in Boston. The goals of the meeting were: To review the current state of COPD genetics research; To discuss existing study populations for COPD genetics research throughout the world; To consider opportunities for collaborations between different COPD research groups through an International COPD Genetics Consortium; To recognize challenges in building COPD genetics collaborations and to discuss them openly; and, To develop a framework for future collaborative studies. Current status of COPD genetics research Many candidate gene association studies have been performed over the past 40 years, but the results have been largely inconsistent. These inconsistencies likely relate to a variety of methodological issues, including small sample sizes, variable definitions of case and control groups, failure to adjust for multiple statistical testing, and inadequate adjustments for population stratification and smoking exposure. Most of the studies describing COPD-associated polymorphisms were performed in White populations (7). A meta-analysis of 20 polymorphisms in 12 candidate genes involved in the protease-antiprotease balance and several an-tioxidant pathways showed that, after combining independent studies, many of these candidate genes had no association with COPD (8). Another factor likely impeding the progress of identifying COPD susceptibility genes is the lack of accurate phenotypic characterization of this complex and heterogeneous disease. Airflow limitation determined by spirometry has been the most common approach to classify and monitor the disease. Structural changes of the lung including emphysema and small airway obstruction are the primary processes that affect lung function (9), but they are not easily discernable with the simple spirometric measures commonly used for phe-notyping COPD. Recent advances in characterizing pathologic changes such as emphysema and remodeling of the small and large airways by quantitative analyses of image data from multidetector computed tomography (CT), together with physiological testing, have been helpful to differentiate COPD phenotypes (emphysema-predominant, airway-predominant, or mixed)(10). Study populations that have chest CT data may help to better identify COPD-associated genetic variations (11). Other potentially relevant COPD phenotypes, such as cachexia and low exercise capacity, have not been widely analyzed in COPD genetic studies. Perhaps the greatest problem in the candidate gene era of COPD genetic studies was improper candidate gene selection, which reflects our limited understanding of COPD pathogenesis. However, the application of genome-wide association studies (GWAS), which provide an unbiased and comprehensive search throughout the genome for common susceptibility loci, has changed the landscape of COPD genetics. Based on GWAS, three genetic loci have been unequivocally associated with COPD susceptibility, located on chromosome 4 near the HHIP gene, on chromosome 4 in the FAM13A gene, and on chromosome 15 in a block of genes which contains several components of the nicotinic acetyl-choline receptor as well as the IREB2 gene. In 2009, a series of studies provided convincing support for these three genetic loci in COPD susceptibility. Pillai and colleagues found genome-wide significant associations of the CHRNA3/CHRNA5/IREB2 region to COPD (12). DeMeo and colleagues performed gene expression studies of normal vs. COPD lung tissues followed by genetic association analysis of COPD (13), suggesting that at least one of the key COPD genetic determinants in the chromosome 15 GWAS region was IREB2. In the Framingham Heart Study (14), the HHIP region was associated with FEV1/FVC at genome-wide significance with replication of the effect on FEV1/FVC demonstrated in an independent sample drawn from the Family Heart Study, and this same region nearly reached genome-wide significance with COPD susceptibility in the Pillai paper (12). Recently, two papers published in Nature Genetics from large general population samples have provided strong support for the association of HHIP SNPs with FEV1/FVC (15, 16). One of these articles, from the CHARGE Consortium, also found evidence for association of FEV1/FVC with the FAM13A locus (15), which has been strongly associated with COPD susceptibility (17). Moreover, several case-control studies from other European populations have replicated these findings by confirming significant associations to the chromosome 15q25 locus (CHRNA3/CHRNA5/IREB2) (18, 19), chromosome 4q31 locus (HHIP) (20, 21), and chromosome 4q22 locus (FAM13 A) (22). Thus, the frustration of inconsistent genetic association results in COPD from the beginning of the last decade has been replaced by optimism regarding the likely importance of the IREB2/CHRNA3/CHRNA5, HHIP, and FAM13A loci in COPD susceptibility.

Interventional Pulmonology Fellowship Accreditation Standards: Executive Summary of the Multisociety Interventional Pulmonology Fellowship Accreditation Committee

&NA; Interventional pulmonology (IP) is a rapidly evolving subspecialty of pulmonary medicine. In the last 10 years, formal IP fellowships have increased substantially in number from five to now > 30. The vast majority of IP fellowship trainees are selected through the National Resident Matching Program, and validated in‐service and certification examinations for IP exist. Practice standards and training guidelines for IP fellowship programs have been published; however, considerable variability in the environment, curriculum, and experience offered by the various fellowship programs remains, and there is currently no formal accreditation process in place to standardize IP fellowship training. Recognizing the need for more uniform training across the various fellowship programs, a multisociety accreditation committee was formed with the intent to establish common accreditation standards for all IP fellowship programs in the United States. This article provides a summary of those standards and can serve as an accreditation template for training programs and their offices of graduate medical education as they move through the accreditation process.

APOM and high-density lipoprotein cholesterol are associated with lung function and per cent emphysema

Chronic obstructive pulmonary disease (COPD) is linked to cardiovascular disease; however, there are few studies on the associations of cardiovascular genes with COPD. We assessed the association of lung function with 2100 genes selected for cardiovascular diseases among 20 077 European-Americans and 6900 African-Americans. We performed replication of significant loci in the other racial group and an independent consortium of Europeans, tested the associations of significant loci with per cent emphysema and examined gene expression in an independent sample. We then tested the association of a related lipid biomarker with forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio and per cent emphysema. We identified one new polymorphism for FEV1/FVC (rs805301) in European-Americans (p=1.3×10−6) and a second (rs707974) in the combined European-American and African-American analysis (p=1.38×10−7). Both single-nucleotide polymorphisms (SNPs) flank the gene for apolipoprotein M (APOM), a component of high-density lipoprotein (HDL) cholesterol. Both were replicated in an independent cohort. SNPs in a second gene related to apolipoprotein M and HDL, PCSK9, were associated with FEV1/FVC ratio among African-Americans. rs707974 was associated with per cent emphysema among European-Americans and African-Americans and APOM expression was related to FEV1/FVC ratio and per cent emphysema. Higher HDL levels were associated with lower FEV1/FVC ratio and greater per cent emphysema. These findings suggest a novel role for the apolipoprotein M/HDL pathway in the pathogenesis of COPD and emphysema. Findings from this study suggest a novel effect of the APOM/HDL pathway in the pathogenesis of COPD and emphysema http://ow.ly/t8Ao9

Venoarterial extracorporeal membrane oxygenation for the management of massive amlodipine overdose

A 50-year-old man was admitted to the intensive care unit with respiratory failure and shock after suffering a massive overdose of amlodipine, lisinopril and hydrochlorothiazide. Despite mechanical ventilation, vasopressors, calcium gluconate, hyperinsulinemia-euglycemia therapy, methylene blue and intravenous fat emulsion, the patient’s respiratory and hemodynamic status deteriorated. Venoarterial extracorporeal membrane oxygenation (ECMO) was initiated to provide cardiopulmonary support in the setting of profound respiratory failure and refractory shock. The patient was placed on ECMO 19 hours after arrival to the hospital, after which vasopressor and ventilatory requirements decreased significantly. The patient was decannulated from ECMO after 8 days and was discharged home after a 56-day hospitalization. Early institution of ECMO should be considered for the management of respiratory failure and refractory shock in the setting of calcium channel blocker overdose when medical therapies are insufficient.

A Genome-Wide Association Study of Chronic Obstructive Pulmonary Disease in Hispanics

RATIONALE Genome-wide association studies (GWAS) of chronic obstructive pulmonary disease (COPD) have identified disease-susceptibility loci, mostly in subjects of European descent. OBJECTIVES We hypothesized that by studying Hispanic populations we would be able to identify unique loci that contribute to COPD pathogenesis in Hispanics but remain undetected in GWAS of non-Hispanic populations. METHODS We conducted a metaanalysis of two GWAS of COPD in independent cohorts of Hispanics in Costa Rica and the United States (Multi-Ethnic Study of Atherosclerosis [MESA]). We performed a replication study of the top single-nucleotide polymorphisms in an independent Hispanic cohort in New Mexico (the Lovelace Smokers Cohort). We also attempted to replicate prior findings from genome-wide studies in non-Hispanic populations in Hispanic cohorts. MEASUREMENTS AND MAIN RESULTS We found no genome-wide significant association with COPD in our metaanalysis of Costa Rica and MESA. After combining the top results from this metaanalysis with those from our replication study in the Lovelace Smokers Cohort, we identified two single-nucleotide polymorphisms approaching genome-wide significance for an association with COPD. The first (rs858249, combined P value = 6.1 × 10(-8)) is near the genes KLHL7 and NUPL2 on chromosome 7. The second (rs286499, combined P value = 8.4 × 10(-8)) is located in an intron of DLG2. The two most significant single-nucleotide polymorphisms in FAM13A from a previous genome-wide study in non-Hispanics were associated with COPD in Hispanics. CONCLUSIONS We have identified two novel loci (in or near the genes KLHL7/NUPL2 and DLG2) that may play a role in COPD pathogenesis in Hispanic populations.

Adhesion molecules, endothelin-1 and lung function in seven population-based cohorts.

Abstract Context: Endothelial function is abnormal in chronic obstructive pulmonary disease (COPD); whether endothelial dysfunction causes COPD is unknown. Objective: Test associations of endothelial biomarkers with FEV1 using instrumental variables. Methods: Among 26 907 participants with spirometry, ICAM-1, P-selectin, E-selectin and endothelin-1 were measured in subsets. Results: ICAM-1 and P-selectin were inversely associated with FEV1 among European-Americans (−29 mL and −34 mL per standard deviation of log-transformed biomarker, p < 0.001), as was endothelin-1 among African-Americans (−22 mL, p = 0.008). Genetically-estimated ICAM-1 and P-selectin were not significantly associated with FEV1. The instrumental variable for endothelin-1 was non-informative. Conclusion: Although ICAM-1, P-selectin and endothelin-1 were inversely associated with FEV1, associations for ICAM-1 and P-selectin do not appear causal.