Prognostic significance of the difference between mixed venous and jugular bulb oxygen saturation in comatose patients resuscitated from a cardiac arrest.

Abstract

To determine the prognostic significance of the difference between mixed venous and jugular bulb oxygen saturation in survivors and non-survivors of a cardiac arrest, we studied 30 comatose patients (21 non-survivors and 9 survivors) resuscitated from a cardiac arrest. We measured mixed venous oxygen saturation (SmvO2) and jugular bulb oxygen saturation (SjO2) immediately after haemodynamic stabilisation (always within 6 h after cardiac arrest) and 6, 12 and 24 h later. In all patients the SjO2 was about 10% lower than the SmvO2 in the first measurement. In the survivors the SjO2 did not change and remained lower than SmvO2 in eight of nine survivors. However, in the non-survivors the SjO2 increased significantly and was finally higher than the SmvO2 in 12 of 20 patients 24 h after cardiac arrest suggesting a decrease in cerebral oxygen consumption due to extensive loss of functional brain tissue. The positive predictive value of (SmvO2-SjO2) < or = 0 for predicting irreversible brain damage at 24 h after cardiac arrest is 93% and the negative predictive value of (SmvO2-SjO2) > 0 is 53%. Sensitivity and specificity are 65 and 89%, respectively. In a previous study we concluded that early jugular bulb oximetry (within 4 h after cardiac arrest) cannot predict cerebral outcome in comatose patients after cardiac arrest. More studies are needed to clarify the role of prolonged monitoring in the prediction of cerebral outcome after cardiac arrest.