“…Use of external ventricular drains for ICP measurement in TBI may limit the ability to derive PRx continuously, particularly when the drain is utilized in the therapeutic management of ICP. [26][27][28] In addition, regardless of the ICP measurement technique, we assume that the ICP measure represents a global measure of pressure, and thus PRx represents a global measure of CA, ignoring potential regional variation in CA capacity. 1,3,5 These concerns mean that despite a large volume of statistical, retrospective, evidence for the benefits of adding of PRx to the battery of neuromonitoring tools, its incorporation into routine clinical practice requires further work.…”