Using a human factors-centric approach to development and testing of a face shield designed for health care workers: A COVID-19 case study for process and outcomes.

BACKGROUND: Face shields are a critical piece of personal protective equipment and their comfort impacts compliant use and thus protectiveness. Optimal design criteria for face shield use in healthcare environments are limited. We attempt to identify factors affecting face shield usability and to test and optimize a face shield for comfort and function in health care settings. METHODS: A broad range of workers in a large health care system were surveyed regarding face shield features and usability. Quantitative and qualitative analysis informed the development of iterative prototypes which were tested against existing shields. Iterative testing and redesign utilized expert insight and feedback from participant focus groups to inform subsequent prototype designs. RESULTS: From 1,648 responses, 6 key elements were identified: ability to adjust tension, shifting load bearing from the temples, anti-fogging, ventilation, freedom of movement, and durability. Iterative prototypes received consistently excellent feedback based on use in the clinical environment, demonstrating incremental improvement. CONCLUSION: We defined elements of face shield design necessary for usability in health care and produced a highly functional face shield that satisfies frontline provider criteria and Emergency Use Authorization standards set by the Food and Drug Administration. Integrating human factors principles into rapid-cycle prototyping for personal protective equipment is feasible and valuable.

Comparison of Nylon Suture Versus 2 Fibrin Glue Products for Delayed Nerve Coaptation in an Animal Model.

PURPOSE: To compare 2 different, commercially available fibrin glue products with nylon suture with regard to repair strength, muscle function, and axon regeneration after delayed nerve repair in an animal model. METHODS: A total of 120 Lewis rats underwent transection of the sciatic nerve. On day 3 after transection, the nerves were reexposed. A primary repair was performed on 40 rats from each group using nylon suture, Tisseel fibrin glue, or Evicel fibrin glue. On days 0, 3, and 7 after repair, 10 rats from each group underwent burst strength testing. Seventy days after repair, 10 rats from each group underwent functional muscle testing and histomorphic analysis of the nerve, with the contralateral limb serving as the control. RESULTS: There was no significant difference in burst strength among the groups on days 0 and 3. On day 7, the burst strength of the Evicel and nylon suture groups was significantly greater than that of the Tisseel group. There were 5 total coaptation failures in both fibrin glue groups and none in the suture group. Seventy days after repair, tetanic muscle strength, muscle mass, axon inner diameter, and g-ratio were equivalent among all groups. Axon counts were equivalent between the nylon suture and Evicel groups, although in the nylon group axon counts were higher than for the Tisseel group. CONCLUSIONS: In an animal model with a 3-day delay in nerve repair, although dehiscences occurred, when the initial repair held, fibrin glue was not inferior to nylon suture with regard to repair strength and muscle recovery. CLINICAL RELEVANCE: Historical concerns regarding spontaneous fibrin glue-based nerve repair dehiscences are well-founded. However, when coaptation is maintained, commercially available fibrin glues support nerve regeneration.

Side-to-side supercharging nerve allograft enhances neurotrophic potential.

INTRODUCTION: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential. METHODS: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes. RESULTS: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool. DISCUSSION: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction.