Helmerhorst et al Ann Intensive Care (2017) 7:20 DOI 10.1186/s13613-017-0246-9 Open Access RESEARCH Hemodynamic effects of short‑term hyperoxia after coronary artery bypass grafting Hendrik J. F. Helmerhorst1,2,3*, Rob B. P. de Wilde1, Dae Hyun Lee4, Meindert Palmen5, Jos R. C. Jansen1, David J. van Westerloo1 and Evert de Jonge1 Abstract Background: Although oxygen is generally administered in a liberal manner in the perioperative setting, the effects of oxygen administration on dynamic cardiovascular parameters, filling status and cerebral perfusion have not been fully unraveled Our aim was to study the acute hemodynamic and microcirculatory changes before, during and after arterial hyperoxia in mechanically ventilated patients after coronary artery bypass grafting (CABG) surgery Methods: This was a single-center physiological study in a tertiary care ICU in the Netherlands Twenty-two patients scheduled for ICU admission after elective CABG were enrolled in the study between September 2014 and September 2015 In the ICU, patients were exposed to a fraction of inspired oxygen (FiO2) of 90% allowing a 15-min wash-in period Various hemodynamic parameters were measured using direct pressure signals and continuous arterial waveform analysis at three sequential time points: before, during and after hyperoxia Results: During a 15-min exposure to a fraction of inspired oxygen (FiO2) of 90%, the partial pressure of arterial oxygen (PaO2) and arterial oxygen saturation (SaO2) were significantly higher The systemic resistance increased (P