Application of System-Theoretic Process Analysis (STPA) for Enhancing Safety in a Ventilator System

Background: In Japan, a significant number of ventilator-related medical accidents continue to be reported, with causes frequently linked to both equipment malfunctions and human errors. Conventional analytical methods often lack the methodological rigor needed for comprehensive safety analysis. Objectives: This study explores the application of System-Theoretic Process Analysis (STPA) as a novel approach to ventilator safety analysis. The goal is to identify potential hazards arising from human errors and device failures and to establish system-level safety constraints. Methods: STPA is employed to construct a control structure diagram of a ventilator system, offering a system-wide perspective to identify Unsafe Control Actions (UCAs) and resulting hazardous scenarios. This approach provides a structured analysis of system interactions to derive safety constraints aimed at reducing risks. Results: STPA successfully identified UCAs and system-level interactions that could lead to hazardous outcomes. Compared with the Critical Incident Report (CIR) by the Japan Council for Quality Health Care (JCQHC), which provides retrospective insights into ventilator-related incidents, STPA demonstrates a systematic and comprehensive methodology. It analyzed the mechanisms by which incidents could arise within the system, considering both human and technical factors. The analysis identified hazardous interactions and provided a foundation for implementing preventive measures. Conclusions: STPA offers a holistic framework for ventilator safety, surpassing traditional analysis methods by addressing complex human-technical interactions. The results contribute to enhanced ventilator safety, improved risk management, and a stronger safety culture across medical devices.