Central Venous Oxygen Saturation as a Predictor of a Successful Spontaneous Breathing Trial from Mechanical Ventilation: A Prospective, Nested Case-Control Study

Ioannis Georgakas1, 3, 5, Afroditi K. Boutou1, 2, *, Georgia Pitsiou1, Ioannis Kioumis4, Milly Bitzani3, Kristina Matei5, Paraskevi Argyropoulou1, Ioannis Stanopoulos1
1 Respiratory Failure Unit, Aristotle University of Thessaloniki, Thessaloniki, Greece
2 Department of Respiratory Medicine, “G. Papanikolaou” Hospital, Thessaloniki, Greece
3 1st Intensive Care Unit, “G. Papanikolaou” Hospital, Thessaloniki, Greece
4 Pulmonary Department, Aristotle University of Thessaloniki, Greece
5 Intensive Care Unit, General Hospital of Veroia, Veroia, Greece

© 2018 Georgakas et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Respiratory Medicine, “G. Papanikolaou” Hospital, Afroditi K. Boutou, Exohi, 57010, Thessaloniki, Greece; Tel: 00306946611433; E-mail:



Weaning from mechanical ventilation is a key element in the care of critically ill patients, and Spontaneous Breathing Trial (SBT) is a crucial step in this procedure. This nested case-control study aimed to evaluate whether central oxygen saturation (ScvO2) values and their changes could independently predict the SBT outcome among mechanically ventilated patients.


A prospective cohort of patients who were mechanically ventilated for at least 48hours and fulfilled the criteria of readiness to wean constituted the study population. All patients attempted a SBT and were then categorized in SBT success group and SBT failure group, based on a combination of criteria which indicated whether SBT was successful or not. Multivariate binary logistic regression analysis was utilized to indicate the independent predictors of SBT success, while the Receiver Operating Characteristic (ROC) curves were used to demonstrate the diagnostic accuracy of these independent predictors.


Seventy-seven patients 69(18-86) years old; 62.3% male) constituted the study population. SBT was successful among 63.6% of them. A decrease in ScvO2 values (ΔScvO2) < 4% between the beginning and the end of the trial independently predicted the successful outcome (OR=18.278; 95% CI=4.017-83.163), along with age, Hemoglobin concentration (Hb) and arterial oxygen saturation (SaO2). Diagnostic accuracy for ΔScvO2 alone (ROC area=0.715) was slightly superior to that of either SaO2 (0.625) or Hb (0.685) to predict SBT success.


ScvO2 is an independent predictor of the weaning outcome and its evaluation may further facilitate the accurate categorization among those patients who pass or fail the SBT.

Keywords: Central venous oxygen saturation, Spontaneous breathing trial, Weaning, Mechanical ventilation, Nested case-control study, Oxygen extraction ratio.