From a systems perspective, the equipment user is a system component. The user is a functional part of the medical system being designed. But the total living system is not often a subject of life science studies in biomedical engineering. If the human user is left out of the design problem, the engineering problem is limited to designing devices whose effectiveness assumes a perfectly functioning human operator. This is a mechanistic approach that does not take into account the performance variability of those who will use equipment in the clinical environment. An adjustment of the recognized role for biomedical engineers who design equipment would help them to act responsively and responsibly in addressing those user problems that can account for half the equipment failures in the acute care environment, and that can adversely and seriously affect patient monitoring, diagnosis, and therapy.