Techniques For Monitoring Jugular Blood Oxygen Saturation And Arteriojugular Venous Lactate Difference After Severe Head Injury

Objective:Ischemia is often seen in patients with severe brain injuries and could be related to outcome. In this study, by monitoring patients’ arteriojugular venous lactate difference (AVDL) and jugular blood oxygen saturation (SjvO2), we intend to answer the following questions:1) whether AVDL and SjvO2 abnormities are common during early stages after brain injury; 2) are SjvO2 and AVDL abnormalities related to patients’ prognosis? 3) how is the relationship between AVDL, SjvO2 and CPP in patients with hypoperfusion?Methods:Thirty-five patients with acute and severe brain injuries were involved in this study. Blood samples were obtained through jugular bulb and femoral artery every six hours during the period of three days after injury. MAP, ICP, lactate, SjvO2, AVDL and CPP were recorded for each patient Recruited patients were divided into the Study Group and the Control Group according to the severity of their brain injuries. Patients’ outcomes were assessed according to the Glasgow Outcome Scale (GOS) at 6 months after injuries. The initial levels of SjvO2 and AVDL were compared between patients having favorable and unfavorable outcomes. The relationships between SjvO2 AVDL and CPP were also investigated.Results:A total number of 478 blood samples were collected. The mean SjvO2 in the Study Group was 0.549 ±0.086, and 0.622±0.013 in the Control Group. For AVDL, the average level is -0.321± 0.078mmol/L in the Study Group and -0.284±0.062 mmol/L in the Control Group.Among the thirty-five patients with acute and severe brain injuries, three patients (9%) had SjvO2≥75% once, two patients (6%) had SjvO2≥ 75% for several times. On the other hand, five patients (16%) had SjvO2≤ 50% once, six patients (17%) had such situation for several times. Five patients had abnormal AVDL once, while another five had several times of abnormal AVDL.One or more episodes of abnormal measurements of SjvO2 and increased AVDL found in study group and the number was used to predict the neurologic outcome. The normal SjvO2 group had good neurologic outcomes comparing to those with SjvO2≥75%(Fiser’s exact propability, p=0.042); comparing with SjvO2≤50% group (X2=6.903,P=0.009).The strong association was found between a poor neurologic outcome and pathologic AVDL measurement(X2=5.303,P=0.021).When CPP<60mmHg, SjvO2 had a positive correlation with CPP (r=0.743, p<0.01). When CPP<60mmHg, AVDL had a negative correlation with CPP (r=0.379, p<0.01).Conclusion:In patients with severe traumatic brain injury, measurements of SjvO2≤50%, SjvO2≥75% or pathologic AVDL recordings were associated with a poor neurologic outcome. AVDL and SjvO2 appeared to be informative regarding to the consequence of low CPP condition. Monitoring SjvO2 and AVDL is valuable in the prediction of prognosis of severe brain injury.