Investigation of a Deep Brain Stimulator (DBS) System.

A deep brain stimulator (DBS) device is a surgically implanted system that delivers electrical impulses to specific targets in the brain to treat abnormal movement disorders. A DBS is like a cardiac pacemaker, but instead of sending electrical signals to the heart, it sends them to the brain instead. When DBS leads and extension wires are exposed in the biological environment, this can adversely affect impedance and battery life, resulting in poor clinical outcomes. A posthumously extracted DBS device was evaluated using visual inspection and optical microscopy as well as electrical and mechanical tests to quantify the damage leading to its impairment. The implantable pulse generator (IPG) leads, a component of the DBS, contained cracks, delamination, exfoliations, and breakage. Some aspects of in vivo damage were observed in localized areas discussed in this paper. The duration of the time in months that the DBS was in vivo was estimated based on multiple regression analyses of mechanical property testing from prior research of pacemaker extensions. The test results of three DBS extensions, when applied to the regressions, were used to estimate the in vivo duration in months. This estimation approach may provide insight into how long the leads can function effectively before experiencing mechanical failure. Measurements of the extension coils demonstrated distortion and stretching, demonstrating the changes that may occur in vivo. These changes can alter the impedance and potentially reduce the effectiveness of the clinical treatment provided by the DBS system. Ultimately, as both DBSs and pacemakers use the same insulation and lead materials, the focus of this paper is to develop a proof of concept demonstrating that the mechanical properties measured from pacemaker extensions and leads extracted posthumously of known duration, measured in months while in vivo, can be used to predict the duration of DBS leads of unknown lifespan. The goal is to explore the validity of the proposed model using multiple regression of mechanical properties.

A three-dimensional parametric adult head model with representation of scalp shape variability under hair.

Modeling the shape of the scalp and face is essential for the design of protective helmets and other head-borne equipment. However, head anthropometry studies using optical scanning rarely capture scalp shape because of hair interference. Data on scalp shape is available from bald men, but female data are generally not available. To address this issue, scalp shape was digitized in an ethnically diverse sample of 100 adult women, age 18-59, under a protocol that included whole head surface scanning and scalp measurement using a three-dimensional (3D) coordinate digitizer. A combined male and female sample was created by adding 3D surface scans of a similarly diverse sample of 80 bald men. A statistical head shape model was created by standardizing the head scan data. A total of 58 anatomical head landmarks and 12 head dimensions were obtained from each scan and processed along with the scans. A parametric model accounting for the variability of the head shape under the hair as a function of selected head dimensions was developed. The full-variable model has a mean shape error of 3.8 mm; the 95th percentile error was 7.4 mm, which were measured at the vertices. The model will be particularly useful for generating a series of representing a target population as well as for generating subject-specific head shapes along with predicted landmarks and dimensions. The model is publicly available online at http://humanshape.org/head/.

Firefighter Hand Anthropometry and Structural Glove Sizing: A New Perspective.

OBJECTIVE: We evaluated the current use and fit of structural firefighting gloves and developed an improved sizing scheme that better accommodates the U.S. firefighter population. BACKGROUND: Among surveys, 24% to 30% of men and 31% to 62% of women reported experiencing problems with the fit or bulkiness of their structural firefighting gloves. METHOD: An age-, race/ethnicity-, and gender-stratified sample of 863 male and 88 female firefighters across the United States participated in the study. Fourteen hand dimensions relevant to glove design were measured. A cluster analysis of the hand dimensions was performed to explore options for an improved sizing scheme. RESULTS: The current national standard structural firefighting glove-sizing scheme underrepresents firefighter hand size range and shape variation. In addition, mismatch between existing sizing specifications and hand characteristics, such as hand dimensions, user selection of glove size, and the existing glove sizing specifications, is significant. An improved glove-sizing plan based on clusters of overall hand size and hand/finger breadth-to-length contrast has been developed. CONCLUSION: This study presents the most up-to-date firefighter hand anthropometry and a new perspective on glove accommodation. The new seven-size system contains narrower variations (standard deviations) for almost all dimensions for each glove size than the current sizing practices. APPLICATION: The proposed science-based sizing plan for structural firefighting gloves provides a step-forward perspective (i.e., including two women hand model-based sizes and two wide-palm sizes for men) for glove manufacturers to advance firefighter hand protection.

Seat and seatbelt accommodation in fire apparatus: Anthropometric aspects.

This study developed anthropometric information on U.S. firefighters to guide fire-apparatus seat and seatbelt designs and future standards development. A stratified sample of 863 male and 88 female firefighters across the U.S. participated in the study. The study results suggested 498 mm in width, 404 mm in depth, and 365-476 mm in height for seat pans; 429-522 mm in width and 542 mm in height for seat back; 871 mm in height for head support; a seat space of 733 mm at shoulder and 678 mm at hip; and a knee/leg clearance of 909 mm in fire truck cab. Also, 1520 mm of lap belt web effective length and 2828 mm of lap-and-shoulder belt web effective length were suggested. These data for fire-truck seats and seatbelts provide a foundation for fire apparatus manufacturers and standards committees to improve firefighter seat designs and seatbelt usage compliance.

Comparison of measured and self-reported anthropometric information among firefighters: implications and applications.

This study evaluated the accuracy of self-reported body weight and height compared to measured values among firefighters and identified factors associated with reporting error. A total of 863 male and 88 female firefighters in four US regions participated in the study. The results showed that both men and women underestimated their body weight ( - 0.4 ± 4.1, - 1.1 ± 3.6 kg) and overestimated their height (29 ± 18 , 17 ± 16 mm). Women underestimated more than men on weight (p = 0.022) and men overestimated more than women on height (p < 0.001). Reporting errors on weight were increased with overweight status (p < 0.001) and were disproportionate among subgroups. About 27% men and 24% women had reporting errors on weight greater than ± 2.2 kg, and 59% men and 28% women had reporting errors on height greater than 25 mm.

Sizing firefighters: method and implications.

OBJECTIVE: This article reports new anthropometric information of U.S. firefighters for fire apparatus design applications (Study 1) and presents a data method to assist in firefighter anthropometric data usage for research-to-practice propositions (Study 2). BACKGROUND: Up-to-date anthropometric information of the U.S. firefighter population is needed for updating ergonomic and safety specifications for fire apparatus. METHOD: A stratified sampling plan of three-age by three-race/ethnicity combinations was used to collect anthropometric data of 863 male and 88 female firefighters across the U.S. regions; 71 anthropometric dimensions were measured (Study I). Differences among original, weighted, and normality transformed data from Study 1 were compared to allowable observer errors (Study 2). RESULTS: On average, male firefighters were 9.8 kg heavier and female firefighters were 29 mm taller than their counterparts in the general U.S. population. They also have larger upper-body builds than those of the general U.S. population. The data in weighted, unweighted, and normality transformed modes were compatible among each other with a few exceptions. CONCLUSION: The data obtained in this study provide the first available U.S. national firefighter anthropometric information for fire apparatus designs. The data represent the demographic characteristics of the current firefighter population and, except for a few dimensions, can be directly employed into fire apparatus design applications without major weighting or nonnormality concerns. APPLICATION: The up-to-date firefighter anthropometric data and data method will benefit the design of future fire apparatus and protective equipment, such as seats, body restraints, cabs, gloves, and bunker gear.

Analysis of firetruck crashes and associated firefighter injuries in the United States.

Motor vehicle crashes are the second leading cause of death for on-duty firefighters. Firetruck crashes, occurring at a rate of approximately 30,000 crashes per year, have potentially dire consequences for the vehicle occupants and for the community if the firetruck was traveling to provide emergency services. Data from the United States Fire Administration and the National Highway Traffic Safety Administration shows that firefighters neglect to buckle their seatbelts while traveling in a fire apparatus, thus putting themselves at a high risk for injuries if the truck crashes, especially in rollover crashes. Despite national regulations and departmental guidelines aiming to improve safety on fire apparatuses, belt use among firefighters remains dangerously low. The results from this study indicate that further steps need to be taken to improve belt use. One promising solution would be to redesign firetruck seatbelts to improve the ease of buckling and to accommodate wider variations in firefighter sizes.

Multimodal quantitative analysis of early pulsed-dye laser treatment of scars at a pediatric burn hospital.

BACKGROUND: The pulsed-dye laser (PDL) is a potential adjunctive therapy for treatment of hyperemic and hypertrophic scars. OBJECTIVE: To compare the effects of early PDL treatment plus compression therapy (CT) with those of CT alone in patients undergoing burn scar reconstruction with split-thickness grafts on an extremity. METHODS: Laser treatments were applied to one half of the graft seam. Standard CT was applied to both halves. Laser treatment was repeated at 6-week intervals until one half reached sufficient clinical improvements. Each half was evaluated just before treatments using quantitative measures of color, scar height, biomechanical properties and clinical features using the Vancouver Scar Scale (VSS). RESULTS: Less quantitative scar erythema and height and greater tissue elasticity were observed after two or three treatments for PDL plus compression than with compression alone. VSS scores showed greater improvement for vascularity, pliability, pigmentation, and height for PDL plus compression than for compression alone. CONCLUSION: PDL treatment in combination with CT appears to reduce scar hyperemia and height and normalize the biomechanical properties of burn-related scars.

Harness sizing and strap length configurations.

OBJECTIVE: This article describes the derivation of strap lengths and adjustments to fall-arrest harnesses and the development of harness size configurations. BACKGROUND: Updated harness sizing configurations are needed to accommodate diverse populations in the current workforce. METHOD: Three-dimensional torso anthropometric data from 243 women and 258 men were incorporated into eight validated equations to develop a cost-effective harness sizing plan and to define strap lengths. RESULTS: To met strap adjustable range goals and to accommodate 95% to 98% of the estimated population, two sizing options were identified. CONCLUSION: Study outcomes suggest system improvement with three to four sizes for women and three to four sizes for men, on which the adjustment ranges of the torso straps were within 15 to 17 cm and within 20 to 23 cm on thigh and hip straps. APPLICATION: This research provided harness sizing and cut-length information for harness design to reduce the risk of worker injury that results from poor fit or improper size selection.

Evaluation of fall arrest harness sizing schemes.

OBJECTIVE: This paper evaluated harness sizing schemes and anthropometric criteria for harness design applications. BACKGROUND: Updated harness sizing systems are needed to accommodate diverse populations in the current workforce. METHOD: Three-dimensional torso scan data and human-harness interfaces from 108 women and 108 men were digitally captured. Abounding box approach was employed to quantify the effect of torso shape and size on fall harness fit. RESULTS: A logistic regression model with eight equations was developed and tested to classify more than 96% of participants to the best-fitting size. CONCLUSION: Study outcomes suggested an alternative system of two sizes for women and three sizes for men over the current four-size unisex system. In addition, thigh strap angle and back D ring location could be utilized along with current harness static fit test criteria to further enhance postfall harness fit predictions. APPLICATION: This research could help reduce the risk of worker injury resulting from poor fit, improper size selection, or failure to don the harness properly.

Effect of weight loss on cellulite: gynoid lypodystrophy.

BACKGROUND: Gynoid lipodystrophy (cellulite) affects most women, and many seek plastic surgery consultation to improve appearance. Various products are offered, but the literature on the cause and treatment is limited. Understanding the biological and biophysical factors that affect severity may facilitate the development of effective therapies. There has been a dramatic increase in the number of people who have lost significant weight as a result of bariatric surgery or medically supervised weight programs. The effect of weight loss on cellulite severity has not been systematically studied and remains a common patient concern. The authors hypothesized that cellulite severity would decrease with weight loss and subsequent decrease in subcutaneous fat in most subjects. METHODS: The authors examined the cellulite changes in female subjects who were enrolled in medically supervised weight loss programs using quantitative surface roughness by three-dimensional laser surface scanning, tissue composition by dual energy x-ray absorptiometry, dermal-subcutaneous structure with three-dimensional ultrasound, and tissue elasticity with biomechanical measurements. RESULTS: The majority of subjects had an improvement in cellulite with weight loss, but the condition worsened for others. Improvement was associated with significant reductions in weight and percentage of thigh fat, significantly higher starting body mass index, and significantly greater initial severity. Cellulite worsened with a significantly smaller starting body mass index, smaller reductions in weight accompanied by no change in percentage of thigh fat, and significant increases in tissue compliance. CONCLUSIONS: Cellulite is a complex condition, and treatments such as weight loss have variable effects on the improvement or worsening of this condition. Additional studies are required to understand how the factors that influence and modulate cellulite severity, particularly those at the level of the subcutaneous tissue septa, can be manipulated to improve this condition.

Quantitative model of cellulite: three-dimensional skin surface topography, biophysical characterization, and relationship to human perception.

Gynoid lipodystrophy (cellulite) is the irregular, dimpled skin surface of the thighs, abdomen, and buttocks in 85% of post-adolescent women. The distinctive surface morphology is believed to result when subcutaneous adipose tissue protrudes into the lower reticular dermis, thereby creating irregularities at the surface. The biomechanical properties of epidermal and dermal tissue may also influence severity. Cellulite-affected thigh sites were measured in 51 females with varying degrees of cellulite, in 11 non-cellulite controls, and in 10 male controls. A non-contact high-resolution three-dimensional laser surface scanner was used to quantify the skin surface morphology and determine specific roughness values. The scans were evaluated by experts and naive judges (n=62). Body composition was evaluated via dual-energy x-ray absorptiometry; dermal thickness and the dermal-subcutaneous junction were evaluated via high-resolution 3D ultrasound and surface photography under compression. Biomechanical properties were also measured. The roughness parameters Svm (mean depth of the lowest valleys) and Sdr (ratio between the roughness surface area and the area of the xy plane) were highly correlated to the expert image grades and, therefore, designated as the quantitative measures of cellulite severity. The strength of the correlations among naive grades, expert grades, and roughness values confirmed that the data quantitatively evaluate the human perception of cellulite. Cellulite severity was correlated to BMI, thigh circumference, percent thigh fat, architecture of the dermal-subcutaneous border (ultrasound surface area, red-band SD from compressed images), compliance, and stiffness (negative correlation). Cellulite severity was predicted by the percent fat and the area of the dermal-subcutaneous border. The biomechanical properties did not significantly contribute to the prediction. Comparison of the parameters for females and males further suggest that percent thigh fat and surface area roughness deviation are the distinguishing features of cellulite.

Sizing and fit of fall-protection harnesses.

Full-body fall-protection harnesses have been a critical work-practice control technology for reducing the number of fall-related injuries and fatalities among construction workers; yet, very little is known about the fit of these harnesses to the population that wears them. This study evaluated the fit and sizing efficacy of a harness system. Seventy-two male and 26 female construction workers participated in the study. Their body size-and-shape information was measured while they were suspended (with a harness) and standing (with and without a harness), using a 3-D full-body laser scanner and traditional anthropometric calipers. Fisher's discriminant analysis results did not point to the need for a change in the current sizing selection scheme by body height and weight for end users. However, an integrated redesign of harness components is needed because 40% of subjects did not pass fit-performance criteria in either the standing or suspended condition. A multivariate accommodation analysis has identified 15 representative body models for the 'standard-size' harness design. These models can serve as a useful population to test harness design until a larger survey of the nation's construction workers can be done. Finally, further developments in 3-D shape quantification methods are recommended to improve the harness design process; the point-to-point anthropometric information currently used seems to be insufficient for harness design.