The Vittamed 105 non-invasive intracranial volumetric wave and cerebral compliance monitor

The Vittamed 105 provides information about changes in the shape of slow, respiratory and pulse volumetric waves inside the cranium, which reflect the brain’s stiffness or compliance. Intracranial volumetric waves have a characteristic shape reflecting the interplay between blood flow in and out of the head and the resistance of cerebral blood vessels. Deflections from normalized volumetric wave show too large or too small compliance. Monitoring intracranial compliance helps assessing patient status and predicting possible rapid changes in ICP.

 

Small increases in brain volume do not lead to immediate increase in ICP because of the ability of the cerebrospinal fluid to be displaced into the spinal canal and slight ability to be absorbed. However, once the ICP has reached particular level (around 20…25 mmHg) small increases in brain volume can lead to marked elevations in ICP. Cerebral compliance monitor provides useful clinical information for the early detection of hemorrhage in post-operative neurosurgical patients and monitoring of CSF shunt performance in patients with hydrocephalus.

 

The device consists of a portable monitoring unit and a disposable headframe, designed to be easily fitted to a patient head with minimal training. No accurate locationof the acoustic pathe is required on the head to generate a signal, and results can be obtained in a few seconds, generating a continuous trace.

 

 

Vittamed 105 cerebral compliance monitor and head set with two ultrasonic transducers

 

 

Technology

The Vittamed 105 uses transintracranial ultrasound to assess the change in the time-of – flight an ultrasound pulse takes to cross the head as intracranial volume varies. The device produces an averaged intracranial volumetric pulse wave, which when compared against a standard reference wave, provides information about how the compliance of the brain is changing.

 

 

 

Screen shot of Vittamed 105 cerebral compliance device demonstrating changes in the shape of the intracranial volumetric pulse wave envelope shape.

 

 

 

A study of the groups of patients has demonstrated that the device can distinguish differences in the cerebral compliance between normal patients and those with spinal stenosis and decompensated hydrocephalus (1).

 

 

Cerebral compliance

 

Intracranial volumetric waves have a characteristic shape reflecting the interplay between blood flow in and out of the head and the resistance of cerebral blood vessels. Deflections from the normalized reference volumetric wave indicate changes in cerebrospinal compliance.

 

Cerebral compliance offers a way to detect early signs of changes in fluid and tissue volume inside the head, which could have benefit in monitoring hemorrhage in post-operative neurosurgical patients or CSF shunt performance in patients with hydrocephalus. An initial study has demonstrated differences in the cerebral compliance between normal patients and those with spinal stenosis and decompensated hydrocephalus (1).

 

 

 

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1 Chambers et al: Physiol Meas: 2005: 26: 1019-1032