Clinical usefulness of continuous central venous oxygen saturation measurement for postoperative management of patients following transthoracic esophagectomy for carcinoma

Background and objective Monitoring of central venous blood oxygen saturation (ScvO 2 ) has recently become easier and safer to perform, but its clinical usefulness following esophagectomy has yet to be established. This study evaluated the use of continuous monitoring of ScvO 2 in this setting, focusing on its relationship with hemoglobin (Hb) concentrations, and reconsideration about an appropriate indication of red blood cell transfusion from the aspect of tissue oxygen balance. Methods A total of 40 patients were assessed following transthoracic esophagectomy for carcinoma. ScvO 2 was measured via a fiberoptic central venous oximetry catheter, postoperatively until discharge from the ICU. Hb was also measured preoperatively and every 8 h postoperatively. Results In correlation between ScvO 2 and Hb values, ScvO 2 could still be greater than 70% in patients with a Hb around 7 g/dl who did not have a bleeding event and maintained a stable circulation. Even when Hb dilution ratio (sampling Hb/preoperative Hb) decreased to around 60% of the preoperative value, ScvO 2 could remain above 65%. Patients who had severe bleeding exhibited a marked decrease of the ScvO 2 value before blood transfusion, but the trend was clearly seen to be a gradual increase of ScvO 2 during transfusions. Conclusions Hb supply is essentially unnecessary if the balance of oxygen supply/demand in tissues is well maintained. ScvO 2 may be a better indicator of a physiological need for blood than Hb in postesophagectomy patients. ScvO 2 is not influenced by hemodilution and lowering of Hb to around 60% of the preoperative value. As well as being a useful start indicator for blood transfusions, ScvO 2 could also become a stop indicator.