Fig. 2.

This matrix provides the schema for the 4 clinical conditions encountered in patients with both ICP and brain oxygen monitors in situ. Type A reflects normal values for both monitors and does not require treatment. Type B involves ICP elevation but normal brain oxygen values; we propose a distinct treatment algorithm for such patients than in those with ICP elevation and unknown P_btO₂ values. Type C patients have hypoxic brains but normal ICP and Type D patients have both brain hypoxia and ICP elevation. An ICP of 22 mmHg discriminates normal (lower) and abnormal (higher) values while P_btO₂ values of 20 mmHg discriminates normal (higher) and abnormal (lower) values. ICP intracranial pressure, P_btO₂ partial pressure of brain oxygen