AimTo describe healthcare workers' experiences of preconditions and patient safety risks in intensive care units during the COVID-19 pandemic. BackgroundHealthcare workers' ability to adapt to changing conditions is crucial to promote patient safety. During the COVID-19 pandemic, healthcare workers' capacity to maintain safe care was challenged and a more in-depth understanding on frontline experiences of patient safety is needed. DesignA qualitative descriptive design. MethodsIndividual interviews were conducted with 29 healthcare workers (nurses, physicians, nurse assistants and physiotherapists) from three Swedish hospitals directly involved in intensive care of COVID-19 patients. Data were analysed with inductive content analysis. Reporting followed the COREQ checklist. ResultsThree categories were identified. Hazardous changes in working conditions describes patient safety challenges associated with the extreme workload with high stress level. Imperative adaptations induced by changed preconditions for patient safety which include descriptions of safety risks following adaptations related to temporary intensive care facilities, handling shortage of medical equipment and deviations from routines. Safety risks triggered by reorganisation of care describe how the diluted skill-mix and team disruptions exposed patients to safety risks, and that safety performance mostly relied on individual healthcare worker's responsibility. ConclusionsThe study suggests that healthcare workers experienced an increase in patient safety risks during the COVID-19 pandemic mainly because the extremely high workload, imperative adaptations, and reorganisation of care regarding skill-mix and teamwork. Patient safety performance relied on the individuals' adaptability and responsibility rather than on system-based safety. Relevance to Clinical PracticeThis study provides insights on how healthcare workers' experiences can be used as a source of information for recognition of patient safety risks. To improve detection of safety risks during future crises, guidelines on how to approach safety from a system perspective must include healthcare workers' perceptions on safety risks. Patient and Public ContributionNone in the conceptualisation or design of the study.