Colin Blood Pressure Monitor for Severe Head Injury

Dr Erhard Lang and Dr Nick Dorsch, Department of Neurosurgery, Westmead Hospital

In October 2002, the Brain Foundation awarded a grant to a team of researchers at Westmead Hospital’s Department of Neurosurgery to purchase equipment that is now being used to study the effects of severe head injury - the phase relationship between arterial cerebral blood flow, cerebral blood flow velocity and intracranial pressure.

Head injury affects hundreds of people in NSW each year, and moderate or mild injury thousands more, with permanent disability affecting many of the survivors. Recent research suggests that the outcome is better in those in whom the normal regulation (“autoregulation”) of blood flow in the brain (usually constant in a wide range of conditions) is preserved. By studying arterial blood pressure and its relationship with the rate of flow of blood in the brain arteries (transcranial Doppler or TCD velocity), a calculation can be made of how well this regulation is preserved, and what effect different treatments are having on it.

Continuous measurement of arterial pressure is necessary for this testing, but normally needs a cannula inserted into an artery, which is only possible in severe head injury and only for a few days. The Colin blood pressure monitor gives a continuous reading of blood pressure without the need for an invasive cannula. It can thus be used at a later stage after severe head injury, and in mild or moderate injury, for this testing of blood flow regulation.
 
The initial project with the Colin monitor has made good progress. Data have been acquired in normal people of a wide age range measuring arterial pressure and transcranial Doppler velocities. Some of the results are unexpected, and in order to be able to interpret the data properly we need to go back to the ICU to obtain a set of confirmatory recordings where we use the Colin and the arterial blood pressure transducer, placed directly in the radial artery, simultaneously. This will be done over the next month.

The next step is then to go to the Brain Injury Unit here at Westmead Hospital and get a set of non-invasive recordings of blood pressure and TCD velocity from patients who have suffered traumatic brain injury and have not yet recovered fully. These recordings will start in April.

We will soon be able to produce an abstract based on the first data set mentioned above, in normals, and we hope to find an suitable conference to present it at later this year. Certainly these data will be put into a manuscript for submission to an appropriate journal. That will be the case for the second study as well.

We have just now successfully published our validation study on TCD and autoregulation in a high profile international journal.

Short term aims are thus to validate the Colin monitor, in normals and in severe head injury, then in the longer term to extend the application of autoregulation testing to the convalescent phase, and to milder brain injury.

The Brain Foundation grant to the researchers was made possible by the generous support of the Ian Tucker Foundation.

Date created: 15 April 2003