Object. Intracranial pressure (ICP) and cerebral perfusion pressure<br />(CPP) are frequently monitored in severely head injured patients. To<br />establish which one (ICP or CPP) is more predictive of outcome and to<br />examine whether there are significant threshold levels in the<br />determination of outcome, receiver-operating characteristic (ROC) curves<br />were used to analyze data in a large series of head-injured patients.<br />Methods. Data were obtained from a total of 291 severely head injured<br />patients (207 adults and 84 children). Outcome was categorized as either<br />independent (good recovery or moderate disability) or poor (severely<br />disabled, vegetative, or dead) by using the Glasgow Outcome Scale;<br />patients were also grouped according to the Marshall computerized<br />tomography scan classification.<br />Conclusions. The maximum value of a 2-minute rolling average of ICP<br />readings (defined as ICPmax) and the minimum. value of the CPP readings<br />(CPPmin) were then used to calculate the sensitivity and specificity of<br />the ROC curves over a range of values. Using ROC curves, a threshold<br />value for CPPmin of 55 mm Hg and for ICPmax of 35 mm Hg appear to be the<br />best predictors in adults. For children the levels appear to be 43 to 45<br />mm Hg for CPPmin and 35 mm Hg for ICPmax. Higher levels of CPPmin seem<br />important in adults with mass lesions. These CPP thresholds (45 min Hg<br />for children and 55 min Hg for adults) are lower than previously<br />predicted and may be clinically important, especially in children, in<br />whom a lower blood pressure level is normal. Also, CPP management at<br />higher levels may be more important in adults with mass lesions. A<br />larger observational series would improve the accuracy of these<br />predictions.
Sedgwick, P. (2013, April 27). Receiver operating characteristic curves. BMJ (Online). https://doi.org/10.1136/bmj.f2493