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BackgroundDevelopment of new treatments for Alzheimer’s disease (AD) has broadened into early interventions in individuals with modest cognitive impairment and a slow decline. The 11-item version of the Alzheimer’s Disease Assessment Scale–Cognitive subscale (ADAS-Cog) was originally developed to measure cognition in patients with mild to moderate AD. Attempts to improve its properties for early AD by removing items prone to ceiling and/or by adding cognitive measures known to be impaired early have yielded a number of ADAS-Cog variants. Using Alzheimer’s Disease Neuroimaging Initiative data, we compared the performance of the 3-, 5-, 11- and 13-item ADAS-Cog variants in subjects with early AD. Given the interest in enrichment strategies, we also examined this aspect with a focus on cerebrospinal fluid (CSF) markers.MethodsSubjects with mild cognitive impairment (MCI) and mild AD with available ADAS-Cog 13 and CSF data were analysed. The decline over time was defined by change from baseline. Direct cross-comparison of the ADAS-Cog variants was performed using the signal-to-noise ratio (SNR), with higher values reflecting increased sensitivity to detect change over time.ResultsThe decline over time on any of the ADAS-Cog variants was minimal in subjects with MCI. Approximately half of subjects with MCI fulfilled enrichment criteria for positive AD pathology. The impact of enrichment was detectable but subtle in MCI. The annual decline in mild AD was more pronounced but still modest. More than 90 % of subjects with mild AD had positive AD pathology. SNRs were low in MCI but greater in mild AD. The numerically largest SNRs were seen for the ADAS-Cog 5 in MCI and for both the 5- and 13-item ADAS-Cog variants in mild AD, although associated confidence intervals were large.ConclusionsThe possible value of ADAS-Cog expansion or reduction is less than compelling, particularly in MCI. In mild AD, adding items known to be impaired at early stages seems to provide more benefit than removing items on which subjects score close to ceiling.Electronic supplementary materialThe online version of this article (doi:10.1186/s13195-016-0170-5) contains supplementary material, which is available to authorized users.

Objectives: The incidence of posterior vessel wall puncture (PVWP) during central line placement with possible subsequent injury to structures lying behind the vein is unknown. At times the internal jugular vein lies immediately anterior to the carotid artery rather than lateral to it, leading to potential arterial puncture should the needle pass through the vein completely. The objective of this study is to evaluate the incidence of PVWP during simulated ultrasound (US)-guided vessel cannulation.Methods: Enrolled subjects were emergency medicine resident and attending physicians. Subjects performed US-guided venous access on simulated blood vessels within gelatin-based US phantoms. While blinded to the purpose of the study, each subject performed successful cannulation of the vessel on separate phantoms, with wire placement confirmed by expert review of a follow-up US. Each phantom was subsequently deconstructed to manually inspect for PVWP.Results: Thirty-five subjects with a range of experience in the technique participated, each performing both transverse and long-axis approaches for a total of 70 cannulations. The overall incidence of PVWP was 34% (95% confidence interval [CI] = 22.9% to 45.1%).Conclusions: This study found a high incidence of inadvertent PVWP during simulated US-guided vessel cannulation in this model. ACADEMIC EMERGENCY MEDICINE 2010; 17:1138-1141 ª 2010 by the Society for Academic Emergency MedicineKeywords: ultrasonography, shock, critical care, emergency medicine, patient simulation A rterial puncture during central venous catheter placement is a known complication of the procedure, with reported incidence up to 11%. 1,2While ultrasound (US) guidance has been shown in several studies to decrease arterial puncture, 1-3 the identification of this event is based on the presence of forceful, pulsatile blood flow from the needle after removal of the syringe. Occult arterial injuries occur when the artery is punctured during the course of the procedure without resultant pulsatile flow through the needle.4 Both recognized and occult arterial injuries may result in significant complications.When using a landmark technique for internal jugular venous access, many practitioners intentionally pass through-and-through the vessel and access the lumen when withdrawing the needle. The use of US allows for direct visualization of the internal jugular vein and internal carotid artery, but commonly demonstrates the vein superficial to the artery. 5 In this scenario, any posterior vessel wall puncture (PVWP) that occurs could result in arterial injury. The objective of this study was to measure the incidence of PVWP during US-guided vessel cannulation using a phantom model. METHODS Study DesignThis was an observational study to assess the incidence of PVWP in a simulated model. The study was approved by the institutional review board.

We have demonstrated simultaneous correction for the optical interference of skin and fat in tissue spectra by using a two-distance fiber-optic probe. We obtained the correction by orthogonalizing the spectra collected at a long source-detector distance (SD) to the spectra collected at a short SD and mapped to the long SD space. The method was validated in tissuelike three-layer phantoms as well as preliminarily in human tissue. After the correction, a partial-least-squares model of the phantoms showed enhanced prediction performance.

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