Human factors engineering validation study for a novel 0.1-mg epinephrine auto-injector

Abstract

Anaphylaxis in infants and young children is increasing. Historically, epinephrine auto-injectors (EAI) were not available in a dose or platform designed for patients who weighed <15 kg, and, therefore, 0.15-mg EAIs were prescribed for these patients. Results of ultrasound studies indicate that currently marketed 0.15-mg EAIs have needle lengths that may strike bone in ∼29 to 43% of patients who weigh <15 kg and result in possible intraosseous injection. An EAI with a more weight-appropriate 0.1-mg dose and shorter needle length has been developed to potentially help minimize the risk of striking bone during epinephrine injection in patients who weigh 7.5-15 kg. A human factors usability study was completed to validate the 0.1-mg EAI user interface. This study was conducted with parents of children who were severely allergic so to evaluate simulated use of the 0.1-mg EAI by the intended user group. Fifteen participants were enrolled and received training on using the 0.1-mg EAI. Approximately 24 hours later, the participants completed a simulated emergency-use scenario by using the 0.1-mg EAI with an infant manikin. The primary end point was successful simulated administration of a meaningful epinephrine dose. All the participants simulated administration of a meaningful epinephrine dose. Fourteen participants successfully used the 0.1-mg EAI per the instructions for use in the simulated emergency-use scenario. One participant did not press the EAI against the thigh for the length of time defined for this critical task; however, the EAI was pressed long enough for complete delivery of the 0.1-mg dose. This study validated the user interface of the 0.1-mg EAI for the intended users, uses, and use environments.