BACKGROUND: Adequate tissue oxygenation is necessary to maintain organ function. Low venous oxygen saturation may reflect impaired tissue oxygenation, and may be used as a predictive tool and a therapeutic target to improve the care of critically ill patients. We therefore conducted a systematic review of the existing literature reflecting these aspects.

METHODS: We searched electronic databases in January 2016 for relevant studies on venous oxygen saturation for treatment guidance and patient outcome. We sub-grouped results based on patient groups and setting.

RESULTS: The search resulted in 5590 papers of which 42 studies were deemed relevant. The majority of the studies in cardiac and abdominal surgery patients showed associations between low venous oxygen saturation and increased mortality and morbidity, in particular increased length of intensive care. However, the cut-off level for low venous oxygen saturation varied between < 55 and 70% and all studies had high risk of bias. In patients with septic shock, recent randomized trials showed no benefit of early resuscitation guided by venous oxygen saturation.

CONCLUSION: Low venous oxygen saturation may be associated with increased mortality, morbidity and length of intensive care in patients following cardiac or abdominal surgery. However, the wide range of cut-off levels and low quality of evidence hampers the clinical application. In patients with septic shock, the present evidence does not support goal-directed therapy using venous oxygen saturation during early resuscitation.