Do ICP-Derived Parameters Differ in Vegetative State from Other Outcome Groups After Traumatic Brain Injury?

In nearly 1,000 traumatic brain injury (TBI) patients monitored in the years 1992-2014, we identified 18 vegetative state (VS) cases. Our database provided access to continuous computer-recorded signals, which we used to compare primary signals, intracranial pressure (ICP)-derived indices and demographic data between VS patients, patients who survived but who were not VS (S), and patients who died (D).

Mean values of ICP, arterial blood pressure (ABP) and cerebral perfusion pressure (CPP) from the whole monitoring periods were compared between the different outcome groups. Secondary indices included pressure reactivity index (PRx), the magnitude of slow ICP vasogenic waves, the pulse amplitude of the first harmonic component of the ICP waveform and heart rate (HR).

Mean blood pressure was lowest in the VS group-significantly in comparison to those who died (p = 0.02) and almost significantly (p = 0.1) in comparison to the patients who survived. Mean ICP in VS patients was lower than those who died (VS, 13 ± 5 mmHg; D, 22 ± 14 mmHg; p < 0.001), but not significantly different from those who survived (p > 0.05). The magnitude of slow vasogenic ICP waves was the same in VS patients and those who died, but significantly lower than in those who survived (S, 1.04 ± 0.57 mmHg; VS, 0.74 ± 0.45; p = 0.01).

Patients who progress to a VS differ from non-VS survivors in displaying decreased power of slow vasogenic waves and from those who die by not experiencing as high a burden of intracranial hypertension.