Therapeutic Aspects of Brain Tissue pO₂ Monitoring after Subarachnoid Hemorrhage

Summary

Prolonged phases ofbrain tissue hypoxia (p_tiO₂ < 10 mmHg)lead to cerebral infarction. Therefore, the present study investigates the role of p_tiO₂ — monitoring to guide hypervolemic hypertensive therapy in patients suffering from severe subarachnoid hemorrhage (SAH). Besides transcranial doppler, neuromonitoring of ICP/CPP was supplemented by p_tiO₂ monitoring. The p_tiO₂ catheter was inserted into viable tissue in the vascular territory with the highest risk for vasospasm. Patients were divided in an infarction (n = 21) and a non-infarction group (n = 11). Critical CPP (< 70 mmHg) as well as hypoxic p_tiO₂ (< 10 mmHg) was significantly more frequent in the infarction group (CPP: 25 vs 13%, p < 0.001; p_tiO₂: 16 vs 7%, p < 0.001). In both groups, over 25% of the critical ptiO2 values occurred at a CPP > 90 mmHg. In the infarction group, 13 patients showed transient phases of hypoxia which normalized under induced hypervolemic hypertension and 5 patients developed persistent hypoxia. In the non-infarction group 6 patients showed transient hypoxia and in 5 patients no hypoxic values could be found. In conclusion, monitoring of p_tiO₂ provides an additional independent parameter to detect hypoxic events and to guide therapy.