Description of the response of a new multi-parametric brain sensor to physiological and pathophysiological challenges...

Monitoring of intracranial pressure (ICP), local cerebral blood flow (CBF) and oxygen is part of modern intensive critical care medicine. Preclinical evaluation of newly developed catheters that should monitor several parameters simultaneously is reported poorly in the literature. The goal of our study was (1) to evaluate a new multi-parametric sensor in brain tissue and (2) to establish a testing protocol using pathophysiological challenges that target measured parameters of the sensor and autoregulatory boundaries and could be used as preclinical standard protocol in future studies.

We describe data from 12 new multi-parametric brain sensors (MPBS) that were implanted into 3 porcine brains and combined measurement of brain tissue oxygenation (ptiO2), ICP, CBF and brain temperature for the first time. Pigs were treated with a period of hyperoxygenation, hypercapnia, hypoxia, dobutamine, and norepinephrine.

None of the 12 MPBS failed. Our testing protocol induced standardized pathophysiological changes that were picked up by the new MPBS as significant alterations in brain ptiO2, ICP and CBF. The magnitude of changes was >20% in most tested MPBS.

An experimental protocol with pre-defined end-points for O2, CO2, blood pressure and cardiac output should be standardized and reported if new sensors for multi-parametric brain monitoring are evaluated. The use of several sensors per brain of only a few animals is sufficient to determine functionality of new sensors in vivo as basis for a larger study with reference sensors and brain injury.