Differences in oxygen content between mixed venous blood and cerebral venous blood for outcome prediction after cardiac arrest.

OBJECTIVE: To assess the usefulness of differences in oxygen content between mixed venous blood and cerebral venous blood for predicting neurological outcome after cardiac arrest.
DESIGN: Observational study.
SETTING: Medical-surgical intensive care unit (IUC) in a university hospital. PATIENTS AND PARTICIPANTS: 34 acutely comatose patients who had been admitted to the ICU after cardiac arrest and successful cardiopulmonary resuscitation, classified according to outcome (group A, brain death; group B, vegetative state; group C, neurological recovery). MEASUREMENTS AND
RESULTS: Between 6 and 18 h (mean 12 +/- 16.3 h) after hemodynamic stability and 24 h later, the patient's neurological status was assessed by means of the Glasgow Coma Scale and blood gas analysis, partial pressure of O2, oxygen content in venous blood from the jugular bulb and mixed venous blood, O2 saturation, and lactate and creatine kinase activity (CK) in CSF were determined. Group C patients had significantly lower lactate and CK levels in CSF as compared with patients in groups A and B. Mean oxygen content in mixed venous blood was higher than that in cerebral venous blood in group C patients, whereas the opposite was found in patients with unfavourable outcome. A positive difference in oxygen content between mixed venous blood and cerebral venous blood showed a sensitivity of 95%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 92% for predicting recovery of consciousness.
CONCLUSIONS: Differences between oxygen content of blood samples from the pulmonary artery and the jugular bulb is a simple measurement that has provided good accuracy in the outcome prediction of brain damage after cardiac arrest treated by resuscitation.