Background: Extracorporeal membrane oxygenation (ECMO) is one of the most invasive rescue therapiesfor acute heart and/or lung failure. Survivors have high rates of adverse mental health outcomes, such aspost-traumatic stress symptoms (PTSS) and manifest post-traumatic stress disorder (PTSD). Yet no studyto date has identified and explored PTSD risk factors in these patients.Objectives: The primary aim of this study was to determine and explore post-traumatic stress risk factorsfor patients treated with ECMO. It also aimed to provide a baseline profile for future hypothesis test-ing with respect to risk factor exposure, level of exposure and post-traumatic stress outcomes in thesepatients.Methods design: Retrospective cohort study.Setting: The study was conducted at the Alfred Hospital Melbourne, Australia.Participants: Patients were selected in 2012 from an Intensive Care Unit (ICU) registry that prospectivelyincluded all patients admitted to ICU and treated with ECMO.Data extraction and analysis: Data were extracted from the ICU ECMO registry, ICU and ward charts,progress notes, referrals, drug charts and discharge letters. Data were descriptively analysed.Results: Patients treated with ECMO are exposed to almost all investigated PTSD risk factors. Theseincluded psychiatric history (psychiatric comorbidities), admission to ICU and treatment (prolongedventilation during prolonged ICU stay), and drug therapy (all patients treated with PTSD risk relateddrugs).Conclusion: ECMO patients are exposed to PTSD risk factors such as young age, mechanical ventilation,drug administration, delirium and agitation. Younger age, heterogeneous conditions, profound illnessseverity and prolonged ICU stay describe the case complexity of patients and may explain these findings.Patients in ICU are increasingly conscious during active treatment and this may have positive or negativepsychological effects. ?Awake? ECMO in which patients are conscious while on active life support mayrepresent a unique PTSD risk factor in this perspective.