Showing papers by "Alan H. Morris published in 2014"

Coefficient of glucose variation is independently associated with mortality in critically ill patients receiving intravenous insulin

Abstract: Both patient- and context-specific factors may explain the conflicting evidence regarding glucose control in critically ill patients. Blood glucose variability appears to correlate with mortality, but this variability may be an indicator of disease severity, rather than an independent predictor of mortality. We assessed blood glucose coefficient of variation as an independent predictor of mortality in the critically ill. We used eProtocol-Insulin, an electronic protocol for managing intravenous insulin with explicit rules, high clinician compliance, and reproducibility. We studied critically ill patients from eight hospitals, excluding patients with diabetic ketoacidosis and patients supported with eProtocol-insulin for < 24 hours or with < 10 glucose measurements. Our primary clinical outcome was 30-day all-cause mortality. We performed multivariable logistic regression, with covariates of age, gender, glucose coefficient of variation (standard deviation/mean), Charlson comorbidity score, acute physiology score, presence of diabetes, and occurrence of hypoglycemia < 60 mg/dL. We studied 6101 critically ill adults. Coefficient of variation was independently associated with 30-day mortality (odds ratio 1.23 for every 10% increase, P < 0.001), even after adjustment for hypoglycemia, age, disease severity, and comorbidities. The association was higher in non-diabetics (OR = 1.37, P < 0.001) than in diabetics (OR 1.15, P = 0.001). Blood glucose variability is associated with mortality and is independent of hypoglycemia, disease severity, and comorbidities. Future studies should evaluate blood glucose variability.

Computational Shape Models Characterize Shape Change of the Left Atrium in Atrial Fibrillation.

Abstract: Shape change of the left atrium (LA) and LA appendage in atrial fibrillation (AF) patients is hypothesized to be linked to AF pathology and to play a role in thrombogenesis; however, many aspects of shape variation in the heart are poorly understood. To date, studies of the LA shape in AF have been limited to empirical observation and summary metrics, such as volume and its likeness to a sphere. This paper describes a more comprehensive approach to the study of the LA shape through the use of computationally derived statistical shape models. We describe practical approaches that we have developed to extract shape parameters automatically from the three-dimensional MR images of the patient. From these images and our techniques, we can produce a more comprehensive description of LA geometric variability than that has been previously possible. We present the methodology and results from two examples of specific analyses using shape models: (1) we describe statistically significant group differences between the normal control and AF patient populations (n = 137) and (2) we describe characteristic shapes of the LA appendage that are associated with the risk of thrombogenesis determined by transesophageal echocardiography (n = 203).

A practical algorithm for improving localization and quantification of left ventricular scar

Abstract: Current approaches to classification of left ventricular scar rely on manual segmentation of myocardial borders and manual classification of scar tissue. In this paper, we propose an novel, semi-automatic approach to segment the left ventricular wall and classify scar tissue using a combination of modern image processing techniques. We obtained high-resolution magnetic resonance angiograms (MRA) and late-gadolinium enhanced magnetic resonance imaging (LGE-MRI) in 14 patients who had ventricular scar from a prior myocardial infarction. We applied (1) a level set-based segmentation approach using a combination of the MRA and LGE-MRI to segment the myocardium and then (2) an automated signal intensity algorithm (Otsu thresholding) to identify ventricular scar tissue. We compared results from both steps to those of expert observers. The LV geometry using the semi-automated segmentation method had a mean overlap of 94% with the manual segmentations. The scar volumes obtained with the Otsu method correlated with the expert observer scar volumes (Dice comparison coefficient of 0.85± 0.11). This proof of concept segmentation pipeline provides a more objective method for identifying scar in the left ventricle than manual approaches.

Airway obstruction by GOLD and ATS/ERS2005 criteria in Caucasian American pulmonary laboratory patients using NHANESIII and ERS/GLI12 prediction equations

Abstract: RATIONALE: GOLD and ATS/ERS2005 use different criteria for diagnosis and severity. NHANESIII and ERS/GLI Prediction Equations produce different lower limits of normal. METHODS: 12,239 reproducible and acceptable spirograms (10 to 95 year old Caucasian males and females from 2001 to 2013). We examined differences in obstruction diagnosis and classification between GOLD and ATS/ERS2005 criteria by patient age, using NHANESIII and the ERS/GLI12 prediction equations (e.g., 100% x [number of 36 year olds with obstruction by GOLD - number of 36 year olds with obstruction by ATS/ERS2005] / [number of 36 year olds]). RESULTS: GOLD classified more patients with obstruction than ATS/ERS2005. Differences were almost identical with NHANESIII and ERS/GLI12 prediction equations and increased with age (Figure 1). 626 (5.1%) of patients with obstruction by GOLD but not ATS/ERS2005 had mild and 614 (4.7%) had ≥moderate obstruction (by GOLD) (Figure 1). CONCLUSION: Diagnosis and classification of airway obstruction in Caucasian Americans is influenced by interpretive criteria (GOLD vs. ATS/ERS2012), but not by the NHANESIII and the ERS/GLI12 prediction equations. ![Figure][1] Figure 1:Upper panel: Obstruction diagnosis using GOLD versus ATS/ERS criteria with NHANESIII and ERS/GLI predictions. Lower panel: % of patients by age obstructed with GOLD but not obstructed with ATS/ERS-2005. [1]: pending:yes