Introduction: In the treatment of severe head injury, our institution employed a guideline (based on the BTF guidelines) that aimed to keep ICP < 20mmHg. Some patients appear to tolerate ICP higher than 20mmHg, presumably due to adequate cerebral blood flow. Our study aim to find out the outcome in patients who had persistently raised ICP.
Methods: We retrospectively reviewed patients admitted to the National Neuroscience Institute, Singapore from 2001 to 2012 with severe head injury who had ICP monitoring. Patients were ranked according to the highest ICP attained which was sustained for more than one hour. They were then divided into the following groups for analysis (Max ICP =<20mmHg, 21-30mmHg and so on in incremental of 10mmHg). The extent of exposure to intracranial hypertension was expressed as the quantum of exposure to ICP above 20mmHg (area under the curve above 20mmHg [mmHg.hour]). Glasgow Outcome Scale (GOS) at 6-months was used as the primary outcome.
Results: 319 patients were included in the study. GOS of 1-3 was defined as bad outcome, and 4-5 good outcome. The proportion of good outcome in ICP groups between 0-50mmHg ranged from 52.1% to 57.1%. This started to decline thereafter: 33.3% in ICP 51-60mmHg, 25.0% for 61-70mmHg, 16.7% for 71-80mmHg, and no good outcome for ICP more than 80mmHg (Figure 1). The quantum of exposure to raised ICP (>20mmHg) did not affect outcome for the groups with ICP 21-40mmHg. For the group with ICP 41-80mmHg, lower exposure 0-500mmHg.hour resulted in 55% good outcome whereas increasing exposure resulted in grim outcome (Figure 2).
Conclusions: Our result suggested that patients with severe head injury could tolerate raised ICP up to 40mmHg. For ICP ranging 41-80mmHg, minimising the time exposure to intracranial hypertension also helped to improve the rate of good outcome.
Patient Care: Our results suggested that patients with ICP 40-80mmHg could still be aggressively treated to lower their ICPs as this was shown in our study to have improved outcome
Learning Objectives: By the conclusion of this session, participants should be able to understand how increasing ICP would affect outcome.