Is non-invasive monitoring of intracranial pressure waveform analysis possible? Preliminary results of a comparative study of non-invasive vs. invasive intracranial slow-wave waveform analysis monitoring in patients with traumatic brain injury.

BACKGROUND: An increasing body of evidence supports the concept that intracranial pressure (ICP) slow B waves represent the auto-regulatory response of spontaneous fluctuations of cerebral perfusion pressure. A relationship between cerebral auto-regulation and clinical outcome in patients with traumatic brain injury has also been established. The objective of our prospective clinical study was to compare the B slow ICP waves obtained invasively by standard ICP monitoring to those obtained noninvasively using a new ultrasound technology.

MATERIAL/METHODS: In the participating institutions, over a period of six months, thirteen consecutive patients (8 males and 5 females) with severe closed head injuries (GCS < 8) were included in our IRB-approved study. Intracranial pressure and B slow waves, as well as arterial blood pressure and waveforms, were evaluated by standard invasive techniques. Additionally, a new non-invasive ultrasound device, Vittamed (Telematics Scientific Laboratory, Kaunas, Lithuania), was employed for monitoring intracranial blood volume slow waves. Using these modalities, it was possible to compare the changes that occurred with invasive monitoring (Correlation factor RI) and the changes that occurred using non-invasive technology (Correlation factor RN).

RESULTS: Bland Altman plot analysis showed positive correlation between the invasively and non-invasively obtained slow intracranial B waves (2sigma = 8.9%, p < 0.0001) and cerebral auto-regulation indexes (RI and RN) (SD = 5%, p < 0.0001). Positive RI and RN values were correlated with poor clinical outcome.

CONCLUSIONS: Ultrasonographic technology (Vittamed) may have significant application in non-invasive continuous cerebrovascular auto-regulation monitoring in patients with severe head injuries.