Application of Global Lung Function Initiative Global Spirometry Reference Equations across a Large, Multicenter Pulmonary Function Lab Population.

Rationale: Global Lung Function Initiative (GLI) Global spirometry reference equations were recently derived to offer a "race-neutral" interpretation option. The impact of transitioning from the race-specific GLI-2012 to the GLI Global reference equations is unknown. Objectives: Describe the direction and magnitude of changes in predicted lung function measurements in a population of diverse race and ethnicity using GLI Global in place of GLI-2012 reference equations. Methods: In this multicenter cross-sectional study using a large pulmonary function laboratory database, 109,447 spirometry tests were reanalyzed using GLI Global reference equations and compared with the existing GLI-2012 standard, stratified by self-reported race and ethnicity. Measurements and Main Results: Mean FEV1 and FVC percent predicted increased in the White and Northeast Asian groups and decreased in the Black, Southeast Asian, and mixed/other race groups. The prevalence of obstruction increased by 9.7% in the White group, and prevalences of possible restriction increased by 51.1% and 37.1% in the Black and Southeast Asian groups, respectively. Using GLI Global in a population with equal representation of all five race and ethnicity groups altered the interpretation category for 10.2% of spirometry tests. Subjects who self-identified as Black were the only group with a relative increase in the frequency of abnormal spirometry test results (32.9%). Conclusions: The use of GLI Global reference equations will significantly impact spirometry interpretation. Although GLI Global offers an innovative approach to transition from race-specific reference equations, it is important to recognize the continued need to place these data within an appropriate clinical context.

The Resident Learning Journey in the Medical Intensive Care Unit.

Background: The medical intensive care unit (MICU) offers rich resident learning opportunities, but traditional teaching strategies can be difficult to employ in this fast-paced, high-acuity environment. Resident perspectives of learning within this environment may improve our understanding of the common challenges residents face and inform novel approaches to transform the MICU educational experience. Objective: We conducted a qualitative study of internal medicine residents to better understand their approach to learning the critical care activities that they are entrusted to perform in the MICU. Methods: Using a thematic analysis approach, we conducted six focus group interviews with 15 internal medicine residents, separated by postgraduate year. A trained investigator led each interview, which was audio-recorded and transcribed verbatim for analysis. Our diverse research team, representing different career stages across the continuum of learning to minimize interpretive bias, identified codes and subsequent themes inductively. We refined these themes through group discussion and sensitizing social learning theory concepts using Wenger's community of practice and organized them to create learner archetypes and a conceptual framework of resident learning in the MICU. Results: We identified three thematic resident learning categories: learning goals and motivation, clinical engagement, and interprofessional collaboration. We distinguished three learner archetypes, the novice, experiential learner, and practicing member, to describe progressive resident development within the interprofessional MICU team, the challenges they frequently encounter, and potential teaching strategies to facilitate learning. Conclusion: We developed a conceptual framework that describes the resident's journey to becoming a trusted, collaborating member of the interprofessional MICU team. We identified common developmental challenges residents face and offer educational strategies that may support their progress. These findings should inform future efforts to develop novel teaching strategies to promote resident learning in the MICU.

Idiopathic Spinal Epidural Lipomatosis in the Lumbar Spine.

Overgrowth of epidural fat, known as spinal epidural lipomatosis (SEL), can cause symptomatic compression of the spinal cord, conus medullaris, or cauda equina. Suggested predisposing factors such as obesity, steroid use, and diabetes mellitus have been based on a few reported cases, many of which were not surgically confirmed. There is a paucity of epidemiological data in surgically confirmed cases for this disorder. The purpose of this independently reviewed, retrospective, matched cohort analysis was to compare the demographics and incidence of comorbidities of patients who underwent lumbar decompression for SEL vs degenerative stenosis without SEL. Two surgeons' databases were reviewed to identify patients older than 18 years who underwent decompression surgery for magnetic resonance imaging-verified, symptomatic lumbar SEL. A matched control group comprised an equal number of patients with degenerative stenosis (n=14). Demographic data, body mass index, symptom type/duration, comorbidities, complications, treatment history, and associated pathology were collected from medical records. Previously suggested risk factors, such as obesity, endocrinopathy, and epidural steroid injections, were not significantly different between the SEL and control groups. Furthermore, there were no differences in operative times, complications, or blood loss. The only noted difference between the 2 groups was the preoperative duration of symptoms, on average double in patients with SEL. This series represents the largest of its kind reported to date. Because symptom duration was the only difference noted, it is postulated to be the result of lack of awareness of SEL. Future prospective study in a larger group of patients is warranted. [Orthopedics. 2016; 39(3):163-168.].

The influence of adjacent level disc disease on discectomy outcomes.

PURPOSE: The state of adjacent level discs and its impact on surgical outcomes following single-level lumbar discectomy have not been previously investigated. The purpose of the present study was to determine if a significant relationship exists between the degree of preoperative adjacent level disc degeneration and post-operative clinical outcomes following lumbar discectomy. METHODS: This study retrospectively used preoperative magnetic resonance imaging (MRI) and prospectively collected data from a randomized clinical trial at two tertiary-care academic hospitals. Patients who underwent a primary, single-level lumbar discectomy were included. Exclusion criteria included prior lumbar surgery. Outcome measures were the Modified Oswestry Disability Index (ODI) score and Visual Analog Scale (VAS) scores for back and leg pain. These were recorded at baseline and at 3 months, 1, and 2 years postoperatively. An independent reviewer graded adjacent level disc degeneration on all preoperative MRIs using the Pfirrmann grading scale. These data were then analyzed for correlation with each outcome measure. RESULTS: Forty-seven patients were included in the study. No statistically significant correlations were found when comparing preoperative 3-month or 1-year postoperative scores or change from baseline of any outcome measure between Pfirrmann grades. Only about half the patients had 2-year follow-up, but at that time point a statistically significant difference in back VAS scores was observed between Pfirrmann groups. No other significant differences were observed at that point. CONCLUSIONS: The degree of preoperative adjacent level degeneration does not significantly affect functional or pain relief outcomes following lumbar discectomy up to 1 year after surgery.

Standardization of α-L-iduronidase enzyme assay with Michaelis-Menten kinetics.

The lack of methodological uniformity in enzyme assays has been a long-standing difficulty, a problem for bench researchers, for the interpretation of clinical diagnostic tests, and an issue for investigational drug review. Illustrative of the problem, α-L-iduronidase enzyme catalytic activity is frequently measured with the substrate 4-methylumbelliferyl-α-L-iduronide (4MU-iduronide); however, final substrate concentrations used in different assays vary greatly, ranging from 25 µM to 1425 µM (Km ≈ 180 µM) making it difficult to compare results between laboratories. In this study, α-L-iduronidase was assayed with 15 different substrate concentrations. The resulting activity levels from the same specimens varied greatly with different substrate concentrations but, as a group, obeyed the expectations of Michaelis-Menten kinetics. Therefore, for the sake of improved comparability, it is proposed that α-L-iduronidase enzyme assays should be conducted either (1) under substrate saturating conditions; or (2) when concentrations are significantly below substrate saturation, with results standardized by arithmetic adjustment that considers Michaelis-Menten kinetics. The approach can be generalized to many other enzyme assays.