The effect of blood transfusion on central venous oxygen saturation in critically ill patients admitted to a neurointensive care unit

SUMMARY Background Literature suggests poorer outcomes during anaemia as well as following red blood cell transfusion ( BT ) in brain injured patients. Recently, central venous oxygen saturation ( ScvO 2 ) has been proposed as a physiological trigger to guide red BT. In this study, we looked at ScvO 2 changes following BT in patients admitted to a neurointensive care unit ( NICU ). Study design In this prospective, observational study, adult, acutely ill neurological patients of >18 years were recruited. The following parameters were measured before and immediately after transfusion and then at 6, 12, 18 and 24 h after transfusion: haemoglobin (Hb), ScvO 2 and central venous oxygen partial pressure ( PcvO 2 ) (blood sampled from central venous catheter). Simultaneously, hemodynamic parameters [central venous pressure ( CVP ), heart rate ( HR ), mean arterial pressure ( MAP ) and systolic blood pressure ( SBP )] were also noted. Results Data from 70 adult patients were analysed. Following BT , significant improvement was noted in Hb, ScvO 2 and all hemodynamic parameters. The ScvO 2 changes correlated significantly with the number of units of BT ( P  = 0·039), pre‐transfusion Hb ( P  = 0·010), ScvO 2 ( P  = 0·001) and PcvO 2 ( P  = 0·001). When receiver operating characteristic ( ROC ) curves were drawn, optimum cut‐off values of baseline ScvO 2 and Hb to predict the need for transfusion in terms of oxygen delivery were 70% and 8·6 gm dL −1 respectively. Discussion Baseline ScvO 2 <70% appears to be a useful physiological trigger for deciding the need for BT in brain injured patients. Whether improvement in ScvO 2 leads to improvement in regional brain oxygenation needs to be studied.