Confounding factors impacting the Glasgow coma score: a literature review

BACKGROUND

The Glasgow coma score (GCS) is a clinical tool used to measure level of consciousness in traumatic brain injury and other settings. Despite its widespread use, there are many inaccuracies in its reporting. One source of inaccuracy is confounding factors which affect consciousness as well as each sub-score of the GCS. The purpose of this article was to create a comprehensive list of confounding factors in order to improve the accuracy of the GCS and ultimately improve decision-making.

METHODS

An English language literature search was conducted discussing GCS and multiple other keywords. Ultimately, 64 out of 3972 articles were included for further analysis.

RESULTS

A multitude of confounding factors were identified which may affect consciousness or GCS sub-scores including the eye exam, motor exam and the verbal response.

CONCLUSIONS

An up-to-date comprehensive list of confounding factors has been created that may be used to aide in GCS recording in hopes of improving its accuracy and utility.

Incomplete partitioning of pollinators by Linum suffruticosum and its co-flowering congeners

PREMISE OF THE STUDY

Linum suffruticosum shows variation in pollinator fit, pollen pick up, and local pollinators that predict pollen deposition rates. The species often co-flowers with other Linum species using the same pollinators. We investigated whether L. suffruticosum trait variation could be explained by local patterns of pollinator sharing and associated evolution to reduce interspecific pollen transfer.

METHODS

Pollinator observations were made in different localities (single species, co-flowering with other congeners). Floral traits were measured to detect differences across populations and from co-flowering species. Reproductive costs were quantified using interspecific hand-pollinations and measures of pollen-tube formation, combined with observations of pollen arrival on stigmas and pollen tube-formation under natural pollination in allopatric and sympatric localities.

KEY RESULTS

The size and identity of the most important pollinator of L. suffruticosum, and whether there was pollinator sharing with co-flowering species, appeared to explain floral trait variation related to pollinator fit. The morphological overlap of the flowers of L. suffruticosum with those of co-flowering species varied, depending on co-flowering species identity. A post-pollination incompatibility system maintains reproductive isolation, but conspecific pollen-tube formation was lower after heterospecific pollination. Under natural pollination at sites of co-flowering with congeners, conspecific pollen-tube formation was lower than at single-species localities.

CONCLUSIONS

Trait variation in L. suffruticosum appears to respond to the most important local pollinator. Locally, incomplete pollinator partitioning might cause interspecific pollination, imposing reproductive costs. This may generate selection on floral traits for reduced morphological overlap with co-flowering congeners, leading to the evolution of pollination ecotypes. This article is protected by copyright. All rights reserved.

Overestimation of Oxygen Saturation Measured by Pulse Oximetry in Hypoxemia. Part 1: Effect of Optical Pathlengths-Ratio Increase

On average, arterial oxygen saturation measured by pulse oximetry (SpO₂) is higher in hypoxemia than the true oxygen saturation measured invasively (SaO₂), thereby increasing the risk of occult hypoxemia. In the current article, measurements of SpO₂ on 17 cyanotic newborns were performed by means of a Nellcor pulse oximeter (POx), based on light with two wavelengths in the red and infrared regions (660 and 900 nm), and by means of a novel POx, based on two wavelengths in the infrared region (761 and 820 nm). The SpO₂ readings from the two POxs showed higher values than the invasive SaO₂ readings, and the disparity increased with decreasing SaO₂. SpO₂ measured using the two infrared wavelengths showed better correlation with SaO₂ than SpO₂ measured using the red and infrared wavelengths. After appropriate calibration, the standard deviation of the individual SpO₂-SaO₂ differences for the two-infrared POx was smaller (3.6%) than that for the red and infrared POx (6.5%, p < 0.05). The overestimation of SpO₂ readings in hypoxemia was explained by the increase in hypoxemia of the optical pathlengths-ratio between the two wavelengths. The two-infrared POx can reduce the overestimation of SpO₂ measurement in hypoxemia and the consequent risk of occult hypoxemia, owing to its smaller increase in pathlengths-ratio in hypoxemia.

The impact of implant-related characteristics on dental implant blooming: An in vitro study

AIM

To assess, in vitro, variables potentially influencing implant blooming using a human-like imaging phantom and 3D-printed mandibles.

MATERIAL AND METHODS

Sixty implants were inserted in 3D-printed mandibles in 26 different configurations in order to examine the impact of implant diameter, presence of a cover screw, implant design/material, implant position, and the presence of additional implants on implant blooming using two cone-beam computed tomography (CBCT) devices (Accuitomo [ACC] and NewTom [NWT]). Two observers measured the amount of implant blooming in both buccolingual and mesiodistal directions. Inter-rater agreement and descriptive statistics, grouped by implant characteristic and CBCT device, were calculated.

RESULTS

Both CBCT devices increased implant diameter (a mean increase of 9.2% and 11.8% for titanium, 20.3% and 24.4% for zirconium, for ACC and NWT, respectively). An increase in implant diameter did not increase the amount of blooming, whereas placing a cover screw did (from 8.0% to 10.9% for ACC, and from 10.0% to 15.6% for NWT). Moreover, implant design, anatomical region, and the presence of another implant also affected the extent of the blooming.

CONCLUSIONS

Dental implants show a clear diameter increase on CBCT, with the effect being more pronounced for zirconium than for titanium implants. Similar effects are likely to occur in the clinical setting, potentially masking nonosseointegration, reducing the dimensions of peri-implant defects, and/or causing underestimation of the buccal bone thickness.

When the internet is wrong: Children's trust in an inaccurate internet or human source

Prior studies have shown that children can select and evaluate information based on the previous accuracy of an informant. The current study examines how 5- to 6-year-old kindergarteners (N = 46) and 7- to 8-year-old second-graders (N = 48) in China judge scientific information provided by the internet or a teacher, and how a source's history of inaccuracy influences participants' judgments. When lacking explicit information about previous accuracy, neither younger children nor older children showed differential trust in the internet or a teacher. After observing the internet providing inaccurate information, children in both age groups decreased their trust in statements from the internet. When the teacher was consistently inaccurate, children in both age groups also showed reduced preference for the teacher's statements. These findings demonstrate that 5- to 8-year-old children take into account history of inaccuracy when deciding whether to request or endorse information from the internet or a teacher.

Impaired Facial Emotion Recognition in Individuals at Ultra-High Risk for Psychosis and Associations With Schizotypy and Paranoia Level

BACKGROUND

Patients with schizophrenia and individuals at ultra-high risk for psychosis (UHR) have been reported to exhibit impaired recognition of facial emotion expressions. This impairment has involved both inaccuracy and negative bias of facial emotion recognition. The present study aimed to investigate whether UHR individuals display both types of impaired facial emotion recognition and to explore correlations between these impairments and schizotypy, as well as paranoia levels, in these individuals.

METHODS

A total of 43 UHR individuals and 57 healthy controls (HC) completed a facial emotion recognition task consisting of 60 standardized facial photographs. To explore correlations, we assessed schizotypy using the Revised Physical Anhedonia Scale and Magical Ideation Scale and paranoia level using the Paranoia Scale and persecution/suspicious item of the Positive and Negative Syndrome Scale in UHR individuals.

RESULTS

Compared with HC, UHR individuals exhibited less accuracy for facial emotion recognition (70.6% vs. 75.6%, p=0.010) and a higher rate of "fear" responses for neutral faces (14.5% vs. 6.0%, p=0.003). In UHR individuals, inaccuracy was significantly correlated with schizotypy scores, but not with paranoia level. Conversely, "disgust" response for neutral faces was the only fear response correlated with paranoia level, and no threat-related emotion response correlated with schizotypy scores.

DISCUSSION

UHR individuals exhibited inaccuracy and negative bias of facial emotion recognition. Furthermore, schizotypy scores were associated with inaccuracy but not with negative bias of facial emotion recognition. Paranoia level was correlated with "disgust" responses for neutral faces but not with inaccuracy. These findings suggest that inaccuracy and negative bias of facial emotion recognition reflect different underlying processes, and that inaccuracy may be a vulnerability marker for schizophrenia.

Analysis of induced error by susceptibility effect in low-density gel dosimeters

Purpose

In low-density (LD) gel dosimeter, diffusive spin-spin relaxation rate (R2)-dispersion caused by susceptibility-induced internal gradient leads to a significant deviation in the measured R2 from the real value. In this study, the effect of induced internal gradient on R2 was visualized and quantified algebraically as an important cause of inaccuracy in LD gel dosimeters.

Materials and Methods

In this method, two sets of LD and unit-density (UD) gel dosimeters were prepared. The LD gel was made by mixing the UD gel with expanded polystyrene spheres. The R2 was used to determine the spatially resolved decay rates due to diffusion in internal magnetic field. The internal gradient was calculated for a multiple spin-echo sequence.

Results

It is shown that in a LD gel, the internal gradient leads to overestimation of mean R2 value (R2_mean). Pixel-by-pixel R2 measurements inside a LD gel showed significant deviation from R2 mapping in UD gel.

Conclusion

It appears that significant differences between R2_mean in a selected region of interest and pixel-by-pixel R2 values are the main source of inaccuracy in dose mapping of a LD gel.

Targeting inaccuracy caused by mechanical distortion of the Leksell stereotactic frame during fixation

Background

The stereotactic frame represents the mainstay of accuracy for targeting in stereotactic procedures. Any distortion of the frame may induce a significant source of error for the stereotactic coordinates.

Objective

To analyze the sources of distortion of the Leksell frame G induced by fixation to the patient's head and to evaluate the clinical impact of frame distortion on the accuracy of targeting in stereotactic procedures.

Methods

We analyzed the torques exerted on the fixation screws after frame placement in a series of patients treated stereotactically by an experienced team. We studied the risk for frame bending in an experimental model of stereotactic frame fixation, with increasing torque of fixation screws in a homogeneous and heterogeneous distribution of torques between the four screws. We assessed the impact of expanding dimensions of bending of the Leksell frame both on surgeries utilizing the stereotactic frame, and on radiosurgical procedures with the Gamma Knife.

Results

Frames were fixed clinically at a range of torques of 0.147–0.522 Nm (mean = 0.348 Nm). The torques did not vary significantly with time. Heterogeneity between the two opposite pairs of screws is often limited, but can reach 96.3%. Distortion of the frame may occur even at minimal levels of torque. Heterogeneity between the two opposite pairs of screws will significantly raise the amount of frame distortion. We found a direct correlation between measures of the frame distortion and extend of the deviation from the stereotactic target in clinical models of stereotactic procedures.

Conclusion

Stereotactic frames were subjected to distortion due to the torque used for frame fixation. The risk of distortion increased with the torque used and the heterogeneity between the torques of the fixation screws. Distortion of the frame was a significant source of inaccuracy of targeting for stereotactic procedures in clinical practice.

The Financial Impact of Inaccurate Blood Glucose Monitoring Systems

OBJECTIVE

An in silico study of type 1 diabetes (T1DM) patients utilized the UVA-PADOVA Type 1 Diabetes Simulator to assess the effect of patient blood glucose monitoring (BGM) system accuracy on clinical outcomes. We applied these findings to assess the financial impact of BGM system inaccuracy.

METHODS

The study included 43 BGM systems previously assessed for accuracy according to ISO 15197:2003 and ISO 15197:2013 criteria. Glycemic responses for the 100 in silico adult T1DM subjects were generated, using each meter. Changes in estimated HbA1c, severe hypoglycemic events, and health care resource utilization were computed for each simulation. The HbA1c Translator modeling approach was used to calculate the financial impact of these changes.

RESULTS

The average cost of inaccuracy associated with the entire group of BGM systems was £155 per patient year (PPY). The average additional cost of BGM systems not meeting the ISO 15197:2003 standard was an estimated £178 PPY more than an average system that fulfills the standard and an estimated £235 PPY more than an average system that appears to meet the ISO 15197:2013 standard.

CONCLUSION

There is a clear relationship between BGM system accuracy and cost, with the highest costs being associated with BGM systems not meeting the ISO 15197:2003 standard. Lower costs are associated with systems meeting the ISO 15197:2013 system accuracy criteria. Using BGM systems that meet the system accuracy criteria of the ISO 15197:2013 standard can help reduce the clinical and financial consequences associated with inaccuracy of BGM devices.

Re-evaluation of individual diameter : height allometric models to improve biomass estimation of tropical trees

Accurate estimation of tree biomass is necessary to provide realistic values of the carbon stored in the terrestrial biosphere. A recognized source of errors in tree aboveground biomass (AGB) estimation is introduced when individual tree height values (H) are not directly measured but estimated from diameter at breast height (DBH) using allometric equations. In this paper, we evaluate the performance of 12 alternative DBH : H equations and compare their effects on AGB estimation for three tropical forests that occur in contrasting climatic and altitudinal zones. We found that fitting a three-parameter Weibull function using data collected locally generated the lowest errors and bias in H estimation, and that equations fitted to these data were more accurate than equations with parameters derived from the literature. For computing AGB, the introduced error values differed notably among DBH : H allometric equations, and in most cases showed a clear bias that resulted in either over- or under-estimation of AGB. Fitting the three-parameter Weibull function minimized errors in AGB estimates in our study and we recommend its widespread adoption for carbon stock estimation. We conclude that many previous studies are likely to present biased estimates of AGB due to the method of H estimation.

Comparison of accuracy of physical examination findings in initial progress notes between paper charts and a newly implemented electronic health record

INTRODUCTION

There have been several concerns about the quality of documentation in electronic health records (EHRs) when compared to paper charts. This study compares the accuracy of physical examination findings documentation between the two in initial progress notes.

METHODOLOGY

Initial progress notes from patients with 5 specific diagnoses with invariable physical findings admitted to Beaumont Hospital, Royal Oak, between August 2011 and July 2013 were randomly selected for this study. A total of 500 progress notes were retrospectively reviewed. The paper chart arm consisted of progress notes completed prior to the transition to an EHR on July 1, 2012. The remaining charts were placed in the EHR arm. The primary endpoints were accuracy, inaccuracy, and omission of information. Secondary endpoints were time of initiation of progress note, word count, number of systems documented, and accuracy based on level of training.

RESULTS

The rate of inaccurate documentation was significantly higher in the EHRs compared to the paper charts (24.4% vs 4.4%). However, expected physical examination findings were more likely to be omitted in the paper notes compared to EHRs (41.2% vs 17.6%). Resident physicians had a smaller number of inaccuracies (5.3% vs 17.3%) and omissions (16.8% vs 33.9%) compared to attending physicians.

CONCLUSIONS

During the initial phase of implementation of an EHR, inaccuracies were more common in progress notes in the EHR compared to the paper charts. Residents had a lower rate of inaccuracies and omissions compared to attending physicians. Further research is needed to identify training methods and incentives that can reduce inaccuracies in EHRs during initial implementation.

ASVCP guidelines: allowable total error guidelines for biochemistry

As all laboratory equipment ages and contains components that may degrade with time, initial and periodically scheduled performance assessment is required to verify accurate and precise results over the life of the instrument. As veterinary patients may present to general practitioners and then to referral hospitals (both of which may each perform in-clinic laboratory analyses using different instruments), and given that general practitioners may send samples to reference laboratories, there is a need for comparability of results across instruments and methods. Allowable total error (TEa ) is a simple comparative quality concept used to define acceptable analytical performance. These guidelines are recommendations for determination and interpretation of TEa for commonly measured biochemical analytes in cats, dogs, and horses for equipment commonly used in veterinary diagnostic medicine. TEa values recommended herein are aimed at all veterinary settings, both private in-clinic laboratories using point-of-care analyzers and larger reference laboratories using more complex equipment. They represent the largest TEa possible without generating laboratory variation that would impact clinical decision making. TEa can be used for (1) assessment of an individual instrument's analytical performance, which is of benefit if one uses this information during instrument selection or assessment of in-clinic instrument performance, (2) Quality Control validation, and (3) as a measure of agreement or comparability of results from different laboratories (eg, between the in-clinic analyzer and the reference laboratory). These guidelines define a straightforward approach to assessment of instrument analytical performance.

Inaccuracy of perceived competence ratings is associated with problem behaviors in 5-year-old children

The authors examined problem behaviors in preschool children as a function of perceived competence. Prior research has demonstrated a link between inaccuracy of self-perceptions and teacher-reported externalizing behaviors in preschool aged boys. This study extended past research by adding data collected from observed behaviors in a laboratory setting, as well as parent reports of internalizing and externalizing behaviors. Five-year-old children completed the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (PSPCSA) in the lab, participated in a 10-min puzzle interaction task with their cotwin and mother, and completed a short task assessing cognitive abilities. Children were grouped into 3 self-esteem categories (unrealistically low, realistic, and unrealistically high) based on comparisons of self-reported (PSPCSA) versus actual competencies for maternal acceptance, peer acceptance, and cognitive competence. Results showed that children who overreported their maternal acceptance and peer acceptance had significantly more parent-reported externalizing problems as well as internalizing problems. There were no significant differences in accuracy for cognitive competence. The findings from this study underscore the negative impact of unrealistically high self-appraisal on problem behaviors in young children.

Application of sigma metrics for the assessment of quality control in clinical chemistry laboratory in Ghana: A pilot study

BACKGROUND

Sigma metrics provide a uniquely defined scale with which we can assess the performance of a laboratory. The objective of this study was to assess the internal quality control (QC) in the clinical chemistry laboratory of the University of Cape Cost Hospital (UCC) using the six sigma metrics application.

MATERIALS AND METHODS

We used commercial control serum [normal (L1) and pathological (L2)] for validation of quality control. Metabolites (glucose, urea, and creatinine), lipids [triglycerides (TG), total cholesterol, high-density lipoprotein cholesterol (HDL-C)], enzymes [alkaline phosphatase (ALP), alanine aminotransferase (AST)], electrolytes (sodium, potassium, chloride) and total protein were assessed. Between-day imprecision (CVs), inaccuracy (Bias) and sigma values were calculated for each control level.

RESULTS

Apart from sodium (2.40%, 3.83%), chloride (2.52% and 2.51%) for both L1 and L2 respectively, and glucose (4.82%), cholesterol (4.86%) for L2, CVs for all other parameters (both L1 and L2) were >5%. Four parameters (HDL-C, urea, creatinine and potassium) achieved sigma levels >1 for both controls. Chloride and sodium achieved sigma levels >1 for L1 but <1 for L2. In contrast, cholesterol, total protein and AST achieved sigma levels <1 for L1 but >1 for L2. Glucose and ALP achieved a sigma level >1 for both control levels whereas TG achieved a sigma level >2 for both control levels.

CONCLUSION

Unsatisfactory sigma levels (<3) where achieved for all parameters using both control levels, this shows instability and low consistency of results. There is the need for detailed assessment of the analytical procedures and the strengthening of the laboratory control systems in order to achieve effective six sigma levels for the laboratory.

Factors affecting blood glucose monitoring: sources of errors in measurement

Glucose monitoring has become an integral part of diabetes care but has some limitations in accuracy. Accuracy may be limited due to strip manufacturing variances, strip storage, and aging. They may also be due to limitations on the environment such as temperature or altitude or to patient factors such as improper coding, incorrect hand washing, altered hematocrit, or naturally occurring interfering substances. Finally, exogenous interfering substances may contribute errors to the system evaluation of blood glucose. In this review, I discuss the measurement of error in blood glucose, the sources of error, and their mechanism and potential solutions to improve accuracy in the hands of the patient. I also discuss the clinical measurement of system accuracy and methods of judging the suitability of clinical trials and finally some methods of overcoming the inaccuracies. I have included comments about additional information or education that could be done today by manufacturers in the appropriate sections. Areas that require additional work are discussed in the final section.