Comparison of changes in central venous oxygen saturation and ST segment changes in a V lead electrocardiographic with changes in haemoglobin in neurosurgical patients undergoing craniotomy and tumour excision: A prospective observational study

Background: The aim of the study was to observe the trends in central venous oxygen saturation (ScvO₂) and ST segment changes with change in haemoglobin (Hb) in patients undergoing acute blood loss during surgery and assess their role as blood transfusion trigger. Methods: Seventy-seven consecutive patients undergoing craniotomy were recruited for this study at a tertiary care institution after obtaining written, informed consent. After establishing standard monitoring, anaesthesia was induced with standard anaesthetic protocol. Central venous cannulation was performed either in the subclavian or internal jugular vein with electrocardiogram guidance to confirm the position of the catheter tip at the superior vena cava-right atrial junction. ScvO₂ was checked at baseline, before and after blood transfusion and at the end of the procedure. ST changes were also recorded at the above times. Comparison of the mean and standard deviation for the haemodynamic parameters was performed between the transfused and not transfused patient groups. Pearson correlation test was done to assess the correlation between the covariates. Receiver operating characteristic (ROC) curve was constructed for the ScvO₂ variable, which was used as a transfusion trigger and the cut-off value at 100% sensitivity and 75% specificity was constructed. Linear regression analysis was done between the change in Hb and the change in ScvO₂ and change in Hb and change in the ST segment. Results: There was a statistically significant positive correlation between the change in ScvO₂ and change in Hb during acute blood loss with a regression coefficient of 0.8 and also between change in ST segment and Hb with a regression coefficient of - 0.132. The ROC curve showed a ScvO₂ cut off of 64.5% with a 100% sensitivity and 75% specificity with area under curve of 0.896 for blood transfusion requirement. Conclusions: We conclude that ScvO₂ and ST segment changes may be considered as physiological transfusion triggers in patients requiring blood transfusion in the intraoperative period.

 

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No conflict of interest has been declared by the author(s).