CEREBRAL ARTERIOVENOUS OXYGEN DIFFERENCE - A PREDICTOR OF CEREBRAL INFARCTION AND OUTCOME IN PATIENTS WITH SEVERE HEAD-INJURY

Jugular bulb oxygen monitoring can be used to estimate the adequacy of cerebral blood flow to support cerebral metabolism after severe head injury. In the present study, the authors studied the cerebral arterio venous oxygen difference (AVDO(2)) before and after treatment in 32 he ad-injured patients (Glasgow Coma Scale scores less than or equal to 8 ) to examine the relationships among AVDO(2) and cerebral perfusion pr essure (CPP), delayed cerebral infarction, and outcome. Fifteen patien ts (Group A) underwent craniotomy for hematoma evacuation and 17 (Grou p B) received mannitol for sustained intracranial hypertension (intrac ranial pressure > 20 mm Hg, > 10 minutes). Radiographic evidence of de layed cerebral infarction was observed in 14 patients. Overall, 17 pat ients died or were severely disabled. Cerebral AVDO(2) was elevated be fore craniotomy or mannitol administration; the mean AVDO(2) for all p atients before treatment was 8.6 +/- 1.8 vol%. Following craniotomy or mannitol administration, the AVDO(2) decreased in 27 patients and inc reased in five patients (mean AVDO(2) 6.2 +/- 2.1 vol% in all patients ; 6 +/- 1.9 vol% in Group A; and 6.4 +/- 2.4 vol% in Group B). The mea n CPP was 75 +/- 9.8 mm Hg and no relationship with AVDO(2) was demons trated. Before treatment, the AVDO was not associated with delayed cer ebral infarction or outcome. B; contrast, a limited improvement in ele vated AVDO(2) after craniotomy or mannitol administration was signific antly associated with delayed cerebral infarction (Group A: p < 0.001; Group B: p < 0.01). Similarly, a limited improvement in elevated AVDO (2) after treatment was significantly associated with an unfavorable o utcome (Group A: p < 0.01; Group B: p < 0.001). In conclusion, these f indings strongly indicate that, despite adequate cerebral perfusion, l imited improvement in elevated cerebral AVDO(2) after treatment consis ting of either craniotomy or mannitol administration may be used to he lp predict delayed cerebral infarction and poor outcome after traumati c brain injury.