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

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 ) has been proposed as a physiological trigger to guide red BT. In this study, we looked at ScvO 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 and central venous oxygen partial pressure (PcvO ) (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 and all hemodynamic parameters. The ScvO changes correlated significantly with the number of units of BT (P = 0·039), pre-transfusion Hb (P = 0·010), ScvO (P = 0·001) and PcvO (P = 0·001). When receiver operating characteristic (ROC) curves were drawn, optimum cut-off values of baseline ScvO and Hb to predict the need for transfusion in terms of oxygen delivery were 70% and 8·6 gm dL respectively.

DISCUSSION

Baseline ScvO <70% appears to be a useful physiological trigger for deciding the need for BT in brain injured patients. Whether improvement in ScvO leads to improvement in regional brain oxygenation needs to be studied.