Fig. 3. Intracranial pressure (ICP) measurements after autoregulation status (impaired or preserved) after the administration of morphine (A ) and fentanyl (B ). All values are mean ± SD (overlapping bars removed for clarity). No differences were found between the impaired (open squares) and preserved (closed circles) autoregulation groups, although ICP increases were slightly greater in patients with impaired autoregulation, both after morphine (3.6 vs. 2.9 mmHg) and with fentanyl (4.8 vs. 2.3 mmHg).