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

Abstract

Monitoring of central venous blood oxygen saturation (ScvO2) 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 ScvO2 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. A total of 40 patients were assessed following transthoracic esophagectomy for carcinoma. ScvO2 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. In correlation between ScvO2 and Hb values, ScvO2 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, ScvO2 could remain above 65%. Patients who had severe bleeding exhibited a marked decrease of the ScvO2 value before blood transfusion, but the trend was clearly seen to be a gradual increase of ScvO2 during transfusions. Hb supply is essentially unnecessary if the balance of oxygen supply/demand in tissues is well maintained. ScvO2 may be a better indicator of a physiological need for blood than Hb in postesophagectomy patients. ScvO2 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, ScvO2 could also become a stop indicator.