1914 Crit Care Med 2012 Vol. 40, No. 6 T raumatic space occupying le- sions and cerebral edema may result in a reduction of the in- tracranial volume reserve fol- lowed by a rise in intracranial pressure (ICP). Subsequently, elevated ICP may lead to herniation of brain tissue, inad- equate cerebral perfusion, ischemia, and death (1, 2). Monitoring and treatment of raised ICP are therefore considered key elements of clinical management of se- vere traumatic brain injury (TBI) (3). ICP monitoring allows early detec- tion of pressure changes and can guide treatment of elevated ICP (4, 5). Based on observational and case studies (6–8), international guidelines recommend rou- tine ICP monitoring in severe TBI (9–11). However, the efficacy of ICP monitoring has never been verified in randomized controlled trials and recent studies have questioned the benefits of ICP monitoring. In one retrospective cohort study, a center using ICP monitoring was compared to a center not using ICP monitoring. Patients in the ICP monitoring center received longer mechanical ventilation and more intense therapy but did not have better outcome (12). Other reports concluded that routine ICP monitoring is associated with worse outcome (13) and higher risk of extracranial complications (14). These counterintuitive findings generated many responses from the field (15–22), pointing out that there is confounding by indica- tion. Patients undergoing ICP monitoring probably sustained more severe injuries than those not undergoing ICP monitor- ing, and therefore have a worse outcome. These comments underscore that in stud- ies evaluating the effect of guidelines on outcome, identification of and controlling for confounding factors are important. Objective: To determine adherence to Brain Trauma Foundation guidelines for intracranial pressure monitoring after severe trau- matic brain injury, to investigate if characteristics of patients treated according to guidelines (ICP+) differ from those who were not (ICP-), and whether guideline compliance is related to 6-month outcome. Design: Observational multicenter study. Patients: Consecutive severe traumatic brain injury patients ($16 yrs, n = 265) meeting criteria for intracranial pressure monitoring. Measurements and Main Results: Data on demographics, injury severity, computed tomography findings, and patient manage- ment were registered. The Glasgow Outcome Scale Extended was dichotomized into death (Glasgow Outcome Scale Extended = 1) and unfavorable outcome (Glasgow Outcome Scale Extended 1–4). Guideline compliance was 46%. Differences between the moni- tored and nonmonitored patients included a younger age (median 44 vs. 53 yrs), more abnormal pupillary reactions (52% vs. 32%), and more intracranial pathology (subarachnoid hemorrhage 62% vs. 44%; intraparenchymal lesions 65% vs. 46%) in the ICP+ group. Patients with a total intracranial lesion volume of ~150 mL and a midline shift of ~12 mm were most likely to receive an intracranial pressure monitor and probabilities decreased with smaller and larger lesions and shifts. Furthermore, compliance was low in pa- tients with no (Traumatic Coma Databank score I -10%) visible intracranial pathology. Differences in case-mix resulted in higher a priori probabilities of dying (median 0.51 vs. 0.35, p < .001) and unfavorable outcome (median 0.79 vs. 0.63, p < .001) in the ICP+ group. After correction for baseline and clinical character- istics with a propensity score, intracranial pressure monitoring guideline compliance was not associated with mortality (odds ratio 0.93, 95% confidence interval 0.47–1.85, p = .83) nor with unfavorable outcome (odds ratio 1.81, 95% confidence interval 0.88–3.73, p = .11). Conclusions: Guideline noncompliance was most prominent in patients with minor or very large computed tomography ab- normalities. Intracranial pressure monitoring was not associated with 6-month outcome, but multiple baseline differences between monitored and nonmonitored patients underline the complex na- ture of examining the effect of intracranial pressure monitoring in observational studies. (Crit Care Med 2012; 40: 1914–1922) KEY WORDS: computed tomography; Glasgow Outcome Scale; guideline adherence; intracranial pressure; multivariate analysis; traumatic brain injury Factors influencing intracranial pressure monitoring guideline compliance and outcome after severe traumatic brain injury* Heleen A.R. Biersteker, MD; Teuntje M.J.C. Andriessen, MSc; Janneke Horn, MD, PhD; Gaby Franschman, MD; Joukje van der Naalt, MD, PhD; Cornelia W.E. Hoedemaekers, MD, PhD; Hester F. Lingsma, PhD; Iain Haitsma, MD; Pieter E. Vos, MD, PhD *See also p. 1993. From the Departments of Neurology (HARB, TMJCA, PEV) and Intensive Care Medicine (CWEH), Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands; Department of Intensive Care Medicine (JH), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Anesthesiology (GF), VU University Medical Center, Amsterdam, The Netherlands; Department of Neurology (JvdN), University Medical Center Groningen, Groningen, The Netherlands; Department of Public Health (HFL), Erasmus Medical Center, Center for Medical Decision Making, Rotterdam, The Netherlands; and Department of Neurosurgery (IH), Erasmus Medical Center, Rotterdam, The Netherlands. The POCON study is funded by the Dutch Brain Foundation (Hersenstichting - HSN-07-01). The authors have not disclosed any potential con- flicts of interest. For information regarding this article, E-mail: p.vos@neuro.umcn.nl Copyright © 2012 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins DOI: 10.1097/CCM.0b013e3182474bde