Lim, Kaiser G.

Abstract Background New insights into community-acquired pleural infection microbiology may enable development of more rapid and accessible diagnostics that can streamline treatment. This study systematically compared molecular approaches for pathogen detection in pleural fluid from patients with such infections. Considering the need for rapid results with minimum hands-on time and test complexity, off-label use of the cassette-based, random-access BIOFIRE Joint Infection Panel (BF-JIP, bioMérieux) with and without supplementary in-house polymerase chain reaction (PCR) assays was evaluated. Methods Pleural fluids from 162 subjects from the Mayo Clinic (Rochester, Minnesota) and Haukeland University Hospital (Bergen, Norway), where molecular tests are routinely used for analyzing pleural fluid, were studied. The performance of the BF-JIP was compared to 16S rRNA gene PCR followed by Sanger and/or next-generation sequencing (16S rRNA gene PCR/sequencing), an in-house PCR panel specifically designed for pleural space infections, and culture. Results The BF-JIP supplemented with 3 in-house PCR assays targeting Fusobacterium nucleatum group, Streptococcus intermedius/constellatus, and Aggregatibacter aphrophilus detected 96.8% of pleural infections, providing complete microbial profiles in 70.1%. In comparison, the detection rate of 16S rRNA gene PCR/sequencing was 92.2%, providing complete microbial profiles in 87.0%. Culture detected bacteria in only 31.9% of pleural fluids, providing complete microbial profiles in 15.3%. Conclusions These results underscore the importance of molecular approaches in diagnosing pleural space infections and demonstrate the feasibility of panel-based PCR-based diagnostics for these sometimes-complex infections. The BF-JIP, designed for testing synovial fluid, could be modified to provide a useful diagnostic for testing pleural fluid.

Abstract Introduction: The variety of pulmonary function tests (PFTs) offered in the pulmonary function lab (PFL) can confuse providers unfamiliar with the clinical role of the individual components of the PFT, potentially leading to repeat tests, diagnostic delays, patient burden, and reduced lab efficiency. We hypothesized that a symptom- and diagnosis-based ordering set will reduce the need for repeat testing visits. Methods: Baseline data (June 2022-June 2023) were first collected to establish PFL performance benchmarks and identify common reasons for incomplete or repeat PFL visits. We then implemented an electronic order set reflecting the clinical need of the PFT, based on symptoms, diagnoses, suspected diagnoses, or other common clinical indication in addition to a physician-supervised, results-driven protocol to allow de-escalation of testing when appropriate The pre-implementation data was compared to the post-implementation data (July 2023-June 2024), evaluating for its impact on PFL access, utilization of the specific PFT components (e.g. methacholine challenge test, MCT), and on diagnoses. Results: During the study period 52,292 PFTs were performed during the pre-implementation phase compared to 58,310 tests in the post-implementation phase. Following intervention, the need for a second PFL visit for the same clinical indication decreased from 26% to 13% (p<0.0001). The same day PFL capacity increased by 3-4 patients per day. 80% of primary care providers reported the new order design was more intuitive and easier to use. Among the specific components of the PFT, there was a significant increase in the number MCTs being performed, from 2.5% to 4%, (p<0.0001), with a change rate ranging between 26 – 81% / month. In a subset analysis of 57 consecutive patients having MCTs, the primary indications were evaluation for cough or wheezing (57.9%), initial asthma evaluation (22.8%), and specifically requested by the ordering provider (19.3%). MCT was not performed in 23% due to a low baseline lung function, difficulty with repeatable efforts, recent bronchodilator administration, or due to complicating comorbidities. Of the 39 tests completed, 89% were deemed appropriate, with 32% having positive results and 42% ultimately diagnosed with asthma. Conclusions: A symptom and/or diagnosis guided ordering set for pulmonary function testing appears to improve the efficiency of the PFL, while improving provider experience, PFL access, as well as on patient burden and diagnoses. Further research is needed to determine potential benefits for provider decision-making and patient outcomes.

Abstract Rationale Pulmonary function tests (PFT) are interpreted in the context of reference values that were based on sex, age, height and previously race/ethnicity. The Global Lung Function Initiative (GLI) published spirometry references equations in 2012 and static lung volume reference equations in 2021. In 2023, the American Thoracic Society recommended removal of race from predictive equations for spirometry using the new race-neutral GLI-Global reference equations. Since the change of spirometry reference equations, we have noticed an increase in number of patients with normal spirometry but a low total lung capacity (TLC), where historically the incidence was less than 5 percent and normal spirometry was used to exclude restriction. The goal of this study was to further investigate this observation and characterize the population of patients with normal spirometry and reduced TLC, which we termed occult restriction. Methods We analyzed our existing PFT database which included 28,415 spirometry tests performed at Mayo Clinic Rochester and Mayo Clinic Florida between 2013 to 2016. 26,856 tests included lung volume measurements. The spirometry was interpreted using both GLI-2012 and GLI-Global reference equations and TLC was interpreted using GLI lung volume reference equations. Patients’ demographics including self-identified race were obtained. Patients with occult restriction were further characterized using descriptive statistics. All data analysis was done using BlueSky Statistics Version 10.3.1. Results Our study showed that 920 (3.4%) patients with normal spirometry using GLI-2012 reference equations had low TLC, while 1526 (5.7%) patients with normal spirometry using GLI-Global reference equations had low TLC. Among these patients, 697 patients had a change from abnormal to normal spirometry interpretation and 91 patients had a change from normal to abnormal spirometry interpretation when using GLI-Global reference equations. Comparing patients of different races and ethnicities, there is increased incidence of occult restriction in Caucasian patients with transition to GLI-Global, while the incidence of occult restriction decreased in African American patients. Patients who identify as African American or Southeast Asian are more likely to have occult restriction than others (Table 1). Conclusions With the change from GLI-2012 to GLI-Global spirometry reference equations, the frequency of occult restriction has increased from 3.4% to 5.7% with predominant effect on Caucasian patients. The clinical implication of this finding requires further study but clinicians need to be vigilant that a normal spirometry may not exclude restrictive lung disease using our current reference equations.

Abstract Rationale Bronchial hyperreactivity (BHR) is a hallmark of asthma, frequently presenting as exercise-induced dyspnea in children and adolescents. Identifying BHR is essential for accurate diagnosis and management of exercise symptoms. The methacholine challenge test (MCT) is the gold standard for diagnosing BHR due to its high sensitivity in detecting airway hyperresponsiveness. However, the MCT requires specialized equipment and stringent protocols, which can limit its availability and use in some clinical settings. An alternative approach, the bronchodilator response test (BDR), is more accessible and assesses the reversibility of airway obstruction following bronchodilator administration. BDR testing is a routine component of asthma diagnostics for evaluating airflow limitation, making it a potentially useful tool for BHR assessment. However, the ability of BDR testing to reliably detect BHR in exertional dyspnea is still uncertain. Prior research has shown that BDR testing, while specific, has low sensitivity for BHR when compared to the MCT, raising questions about its standalone utility in clinical practice. The objective of this study was to evaluate the diagnostic performance of the BDR in detecting bronchial hyperreactivity in exertional dyspnea, using the MCT as the reference standard. By analyzing sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), we aimed to assess whether BDR testing could serve as a reliable alternative to MCT for diagnosing BHR. Methods We conducted a retrospective study of pediatric patients who underwent cardiopulmonary exercise testing, BDR, and MCT as part of their assessment for exertional dyspnea from July 2020 to February 2023. Patients up to 18 years of age were included. A positive BDR was defined by a 10% or greater improvement in FEV1% or FVC%, while a positive MCT was defined by a 20% reduction in FEV1%. Data are presented in a 2x2 table, with the MCT as the reference standard. Results and Conclusion In a cohort of 98 patients, 20 underwent both bronchodilator and methacholine testing. The BDR test, using MCT as the reference, showed a sensitivity of 16.7%, specificity of 87.5%, PPV of 66.7%, and NPV of 41.2%. These results suggest that, due to its low sensitivity, BDR testing alone is insufficient for BHR detection when clinical suspicion of asthma is high. The MCT remains the preferred diagnostic method, though using both tests may provide a more comprehensive evaluation of airway reactivity in children presenting with exercise symptoms.

Abstract Rationale Exertional dyspnea in children presents a complex diagnostic challenge, often requiring multiple evaluations to uncover underlying etiologies. Exercise testing is the standard for diagnosing exercise-induced bronchoconstriction (EIB) in children but requires significant resources. Fractional exhaled nitric oxide (FeNO), a marker of airway inflammation, has been proposed as an easier alternative to predict the need for exercise testing. The aim of this study is to evaluate the diagnostic utility of fractional exhaled nitric oxide (FeNO) as a non-invasive marker of bronchial hyperreactivity in pediatric patients with exertional dyspnea, by assessing its sensitivity, specificity, and predictive values in comparison to cardiopulmonary exercise testing (CPET), the gold standard for diagnosing exercise-induced bronchoconstriction (EIB). This study seeks to determine whether FeNO can reliably guide the need for CPET, potentially streamlining the diagnostic process in children with suspected EIB, while also identifying any limitations of FeNO as a standalone diagnostic tool. Methods In this retrospective study, we reviewed pediatric patients up to 18 years of age who presented with unexplained dyspnea and underwent both CPET and FeNO testing from July 2020 to February 2023. A post-exercise decline in FEV1% of ≥10% during CPET defined a positive result for EIB. For FeNO, a threshold of ≥25 parts per billion (ppb) was considered indicative of bronchial hyperreactivity. Diagnostic agreement between FeNO and CPET was analyzed using a 2x2 table, with CPET as the reference standard. Results Among 98 patients who completed CPET, the cohort had a mean age of 14 years (SD ± 2.42), mean BMI of 22.2 kg/m² (SD ± 5.25), and 71% were female. Of these, 40 patients also underwent FeNO testing. Compared to CPET, FeNO exhibited a sensitivity of 100%, a specificity of 2.6%, a positive predictive value of 5.1%, and a negative predictive value of 100% for identifying bronchial hyperreactivity in this setting. Conclusion FeNO testing shows high sensitivity but limited specificity for detecting bronchial hyperreactivity, effectively ruling out but not confirming it independently of CPET. These findings reinforce the essential role of CPET in diagnosing EIB and suggest that FeNO may serve best as an adjunctive tool, rather than a primary diagnostic measure, in evaluating children with exertional dyspnea. A limitation of this study is the reliance on a single FeNO threshold, which may not account for individual variability in bronchial inflammation responses.

Abstract Rationale Exertional dyspnea in children often necessitates a thorough evaluation to determine potential causes, with bronchial hyperresponsiveness (BHR) and exercise-induced bronchoconstriction (EIB) being among the most common. Cardiopulmonary exercise testing (CPET) is widely recognized as the gold standard for diagnosing EIB; however, it requires significant patient cooperation and specialized resources. The methacholine challenge test (MCT), a bronchial provocation test, is commonly employed to evaluate baseline airway hyperreactivity. Nonetheless, its reliability in predicting EIB in pediatric patients experiencing exertional dyspnea has not been well established. This study aims to evaluate the diagnostic accuracy of MCT compared to CPET in detecting BHR among pediatric patients with unexplained dyspnea. This assessment will help determine the potential of MCT as a complementary diagnostic tool for EIB. Methods We conducted a retrospective cohort study involving pediatric patients (up to 18 years of age) who underwent both CPET and MCT as part of their clinical evaluation for exertional dyspnea from July 2020 to February 2023. A reduction of ≥20% in FEV1% was considered a positive result for the methacholine challenge. In the CPET, a decrease of ≥10% in FEV1% post-exercise was indicative of EIB. The results from both tests were compiled in a 2x2 table, using MCT as the reference standard. Results Out of the 98 patients who underwent CPET, 53 also completed a methacholine challenge test. The mean age of participants was 14 years (SD ± 2.42), with a mean BMI of 22.2 kg/m² (SD ± 5.25), and 71% of the patients were female. Using CPET as the reference standard, the MCT demonstrated a sensitivity of 66.7%, specificity of 58%, positive predictive value of 8.7%, and a negative predictive value of 96.7% for identifying BHR in patients with exertional dyspnea. Conclusions MCT exhibited moderate sensitivity and specificity, and a high negative predictive value, indicating its effectiveness in ruling out BHR in children with exertional dyspnea. However, it is less reliable as a standalone diagnostic tool for EIB, and CPET remains essential for an accurate diagnosis of EIB in these patients.

Abstract Rationale: Cardiopulmonary exercise testing is a unique tool for simultaneously assessing cardiopulmonary and metabolic responses at peak exercise, making it invaluable for diagnosing unexplained dyspnea and fatigue, common issues in cardiovascular and pulmonary clinics. However, its use is often limited by complex guidelines, restricted lab access, technical demands, and high costs. The Veterans Specific Activity Questionnaire (VSAQ), developed by Meyers et al., offers a practical way to estimate metabolic equivalents and maximum oxygen consumption to assess exercise capacity. While primarily validated in a male population, the VSAQ lacks sufficient research in diverse ethnic and gender groups. Broader validation could enhance personalized cardiopulmonary testing, support equitable healthcare resource allocation, and help lower costs. Methods: In this prospective observational study, participants were included if they were 18 years or older and capable of completing a cardiopulmonary exercise test. Participants were excluded if they had known abnormal breathing patterns at baseline and if they had any contraindication for cardiopulmonary exercise and pulmonary function testing. A total of 17 patients without known cardiopulmonary disease provided informed consent and completed the brief self-administered VSAQ following the cardiopulmonary exercise test. The VSAQ was used to estimate maximal exercise capacity in metabolic equivalents, which was then compared to the actual maximal exercise capacity achieved on a bike ergometer, as recorded in the electronic medical records. Results: A linear regression analysis indicated a marginal association between VSAQ results (METS) and CPET METS, accounting for 22.2% of the variance in CPET METS (p=0.056). This finding suggests a potential, though not statistically significant, positive relationship between VSAQ METS scores and CPET MET. A linear regression analysis indicated a marginal association between VSAQ calculated Peak VO₂ and observed CPET Peak VO₂ (o₂/kg/min), explaining 21.6% of the variance in CPET Peak VO₂ (p=0.060). This suggests a potential positive relationship between VSAQ calculated Peak VO₂ and CPET Peak VO₂, though the association did not reach statistical significance. Conclusion: In this preliminary sample of patients without known cardiopulmonary disease, the VSAQ demonstrated accuracy in predicting maximum oxygen consumption at peak exercise. With further validation and larger sample size, the VSAQ could become a valuable adjunctive tool for assessing patients with unexplained dyspnea and fatigue, supporting more efficient diagnostic evaluations. Additionally, the VSAQ may serve as a practical follow-up measure to track clinical improvement after therapeutic interventions in this specific population.

Abstract Background: Tracheobronchomalacia (TBM) presents diagnostic challenges due to its nonspecific symptoms and variability in diagnostic methods. This study evaluates physician concordance in TBM diagnosis and phenotyping using chest computed tomography (CT) scans with dynamic expiratory views. Methods: We conducted a retrospective cross-sectional study at Mayo Clinic Rochester, analyzing 150 patients with dynamic expiratory CT scans. Three specialists—a thoracic radiologist, a bronchoscopist, and a pulmonologist—reviewed identical CT scans, blinded to prior interpretations. Inter-rater agreement was assessed using Fleiss's Kappa for TBM diagnosis and Cohen's Kappa for TBM phenotype classification into six categories: No TBM, Excessive Dynamic Airway Collapse (EDAC), Crescent Type, Circumferential Type, Saber-Sheath Type, and Mixed Type. Results: Among the 150 patients, 54 (36%) were diagnosed with TBM or EDAC. TBM was more prevalent in males, older individuals, and smokers. Agreement among specialists was substantial for TBM diagnosis (Fleiss’s Kappa = 0.61, p < 0.001) but moderate for phenotype classification (Fleiss’s Kappa = 0.52, p < 0.001). The highest concordance was between the thoracic radiologist and the pulmonologist (Cohen's Kappa = 0.68), while the lowest was between the bronchoscopist and other specialists. Conclusion: There is substantial agreement in TBM diagnosis using chest CT scans with dynamic expiratory views, but moderate variability in phenotyping. Standardizing criteria and integrating pulmonary function testing could enhance diagnostic consistency and clinical relevance.