Lora A. Cavuoto

Obesity-related differences in muscular capacity during sustained isometric exertions.

Over one-third of the world adult population is overweight or obese, and the prevalence continues to increase. Obesity is a risk factor for injury, and the growing prevalence may be associated with increases in the future incidence and cost of injuries. In this study, we examined obesity-related differences in muscular capacity during sustained isometric exertions involving hand grip, shoulder flexion, and trunk extension. Thirty-six young individuals who were obese or not obese (aged 18-29) completed these exertions at fixed levels of absolute loads involving low-moderate levels of effort. Individuals who were obese had an overall ∼20% higher absolute strength, but ∼20% lower relative strength. These differences were most evident in the hand grip and shoulder exertions. Parameters of fitted exponential relationships between endurance time and task demands (as a percentage of strength) were similar in both groups. Perceptual and performance responses were also consistent between groups. Accordingly, we conclude that obesity may not substantially influence muscular capacity for these tasks.

Corneal birefringence mapped by scanning laser polarimetry

Corneal birefringence affects polarization-sensitive optical measurements of the eye. Recent literature supports the idea that corneal birefringence is biaxial, although with some disagreement among reports and without considering corneas with very low values of central retardance. This study measured corneal retardation in eyes with a wide range of central corneal retardance by means of scanning laser polarimetry (GDx-VCC, Carl Zeiss Meditec, Inc.), which computes the retardance and slow axis of the cornea from images of the bow tie pattern formed by the radial birefringence of the macula. Measurements were obtained at many points on the cornea by translating the instrument. Data were compared to calculations of the retardation produced by a curved biaxial material between two spherical surfaces. Most corneas showed one or two small areas of zero retardance where the refracted ray within the cornea aligned with an optical axis of the material. The retardation patterns in these corneas could be mimicked, but not accurately described, by the biaxial model. Two corneas with large areas of low retardance more closely resembled a uniaxial model. We conclude that the cornea, in general, behaves as a biaxial material with its fastest axis perpendicular to its surface. Some locations in a few corneas can be uniaxial with the optical axis perpendicular to the surface. Importantly, corneal birefringence varies greatly among people and, within a single cornea, significantly with position.

A heuristic checklist for an accessible smartphone interface design

Smartphone technology has evolved into a multi-functional device with advanced capabilities, but this mobile technology remains inaccessible to many individuals with visual impairments or upper extremity disabilities. This paper provides a heuristic checklist for accessible smartphone interface design, developed through reviewing existing design standards and guidelines and validating these guidelines with user involvement. Specifically, a set of preliminary user requirements (59 items) was extracted from existing standards, guidelines, and user requirements regarding mobile handheld device accessibility. Subsequently, the requirement set was filtered using a participatory method and then integrated to create an operational version of design guidelines. These guidelines were then used in a heuristic evaluation and usability testing on high-fidelity prototypes produced by a commercial manufacturer. A heuristic checklist for designing accessible smartphones was formed, which may also be applicable to other touchscreen handheld devices (e.g., printer screen) in terms of accessibility features. The initial set of 59 user requirements was re-organized into 44 statements in six general categories: mechanical controls, display, speech and general operation controls, audio feedback controls, touch-operated controls, and others. Using results from both qualitative and quantitative methods provides support, though with some limitations, for this accessibility checklist. This checklist is intended as a practical design support tool for use in early design phases of handheld products. A number of challenges and limitations are discussed as well.

The influences of obesity and age on functional performance during intermittent upper extremity tasks.

In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can modify job demands and affect worker capacity in terms of muscular and psychomotor function. However, there is a lack of empirical studies quantifying the work-relevant (or ergonomic) impacts related to task demands, capacities, and their potential imbalance. Eight obese and eight non-obese participants from each of two age groups (18–25 and 50–65 years) completed three endurance tasks involving fixed levels of task demands: hand grip, shoulder flexion, and a simulated assembly task using the upper extremity. Measures of functional performance including endurance, discomfort, motor control, and task performance were recorded for each of the task conditions. Endurance times were ∼60% longer for the non-obese group, and older participants had longer endurance times; however there was no evidence of interactive effects of obesity and age. Obesity also impaired functional performance, as indicated by higher rates of strength loss, increases in discomfort, and declines in task performance. These observed impairments may reflect underlying physiological differences among individuals who are obese, but that are independent of age. Obesity-related impairments may have implications for the design of work duration and demand level to prevent fatigue development for workers who are obese.

Ambulatory movements, team dynamics and interactions during robot-assisted surgery

To analyse ambulatory movements and team dynamics during robot‐assisted surgery (RAS), and to investigate whether congestion of the physical space associated with robotic technology led to workflow challenges or predisposed to errors and adverse events.

The effects of obesity, age, and relative workload levels on handgrip endurance.

The purpose of the study was to examine obesity and age effects on handgrip endurance across a range of relative workload levels. Forty-five non-obese and obese younger and older females performed fatiguing handgrip exercises at 20, 40, 60, and 80% of relative handgrip strength. The younger obese group demonstrated ∼7% greater strength, 32% shorter endurance times, and ∼34% faster rate of strength loss, accompanied by heightened perception of effort, than the younger non-obese group. However, these obesity-related differences were not observed in the older age group. Moreover, there were no interactions between relative workload levels, obesity, and age on any of the fatigue measures. Findings obtained here suggest that work-rest schedules computed from existing force endurance prediction models may not be protective of the younger obese working population.

Evaluation and Impact of Workflow Interruptions During Robot-assisted Surgery

OBJECTIVE To analyze and categorize causes for interruptions during robot-assisted surgery. METHODS We analyzed 10 robot-assisted prostatectomies that were performed by 3 surgeons from October 2014 to June 2015. Interruptions to surgery were defined in terms of duration, stage of surgery, personnel involved, reasons, and impact of the interruption on the surgical workflow. RESULTS The main reasons for interruptions included the following: console surgeons switching (29%); preparation of the surgical equipment, such as cleaning or changing the camera (29%) or an instrument (27%); or when a suture, stapler, or clip was needed (12%). The most common interruption duration was 10-29 seconds (47.6%), and the least common interruption duration was greater than 90 seconds (3.6%). Additionally, about 14% of the interruptions were considered avoidable, whereas the remaining 86% of interruptions were necessary for surgery. CONCLUSION By identifying and analyzing interruptions, we can develop evidence-based strategies to improve operating room efficiency, lower costs, and advance patient safety.

The Loud Surgeon Behind the Console: Understanding Team Activities During Robot-Assisted Surgery

OBJECTIVES To design a data collection methodology to capture team activities during robot-assisted surgery (RAS) (team communications, surgical flow, and procedural interruptions), and use relevant disciplines of Industrial Engineering and Human Factors Engineering to uncover key issues impeding surgical flow and guide evidence-based strategic changes to enhance surgical performance and improve outcomes. DESIGN Field study, to determine the feasibility of the proposed methodology. SETTING Recording the operating room (OR) environment during robot-assisted surgeries (RAS). The data collection system included recordings from the console and 3 aerial cameras, in addition to 8 lapel microphones (1 for each OR team member). Questionnaires on team familiarity and cognitive load were collected. PARTICIPANTS In all, 37 patients and 89 OR staff members have consented to participate in the study. RESULTS Overall, 37 RAS procedures were recorded (130 console hours). A pilot procedure was evaluated in detail. We were able to characterize team communications in terms of flow, mode, topic, and form. Surgical flow was evaluated in terms of duration, location, personnel involved, purpose, and if movements were avoidable or not. Procedural interruptions were characterized according to their duration, cause, mode of communication, and personnel involved. CONCLUSION This methodology allowed for the capture of a wide variety of team activities during RAS that would serve as a solid platform to improve nontechnical aspects of RAS.

Modeling the Spread of an Obesity Intervention through a Social Network

With the growing prevalence of obesity and the public health implications, it is critical to develop and evaluate potential interventions. One approach is to investigate the spread of positive health outcomes through a social network. We employ the ground concepts of spread maximization problem and adapt it to best reflect the dynamics of a weight loss intervention. A diffusion model is then employed for the propagation of weight loss effect throughout the network of obese and overweight individuals. This diffusion model integrates both personal attributes and network-related attributes of an individual while engaged in a weight loss program. Simulation findings suggest that choosing initial agents based on individual attributes, including ability to lose weight, body mass index, and threshold, produced the highest total weight loss in the network. Greedy algorithm was also applied to choose the most effective subset of initial seeds.

Influences of Obesity on Job Demands and Worker Capacity

Evidence suggests that the growing prevalence of obesity in the workforce has resulted in an increase in the incidence and cost of musculoskeletal injuries. Obesity can modify job demands and affect worker capacity in terms of anthropometry and occupational biomechanics, which may place workers at greater risk of injury. This paper presents a review of studies quantifying the work-relevant impacts of obesity, specifically related to work task demands, capacities, and their potential imbalance. The increased body fat that accompanies obesity leads to larger anthropometric dimensions and inertial parameters, particularly in the trunk and thigh areas. Consequently, individuals who are obese adjust their work postures and motions as an accommodation. These changes may affect the biomechanical demands on the joints and increase the burden on the musculoskeletal system. Independent of job demands, obesity-related differences also occur with respect to strength, fatigue, and task performance. Directions for future research are provided, focusing on the need for workplace redesign to account for changing workforce demographics.