Indications for ICP monitoring. Are there clinical or CT findings that predict the development of intracranial hypertension and so can guide decision making about ICP monitor placement?

Reference	# of patients	Design	Grade crit.	Results	Caveats
Hukkelhoven et al. [105]	134 monitored patients	Single-centre, retrospective observational analysis of admission clinical predictors of ICP elevation	Low	No univariate predictors with p < 0.05. Model discrimination (AUC) = 0.50 (95 % CI 0.41–0.58) and calibration (Hosmer–Lemeshow goodness of fit) = 0.18	No admission CT data. No control for decision to monitor. Subjective classification of intracranial hypertension. Used only hourly ICP data
Toutant et al. [6]	218	Single-centre, retrospective analysis of prospective observational data on correlation of cisterns on admission CT and ICP	Low	74 % of monitored patients with absent cisterns had ICP > 30 mmHg	Lack of rigorous definition and standardization of cisternal compression
Mizutani et al. [7]	100	Single-centre, retrospective analysis of correlation of admission CT parameters and initial ICP	Low	Admission CT findings that contributed to predicting initial degree of intracranial hypertension included (in order of predictive power) cisternal compression, subdural size, ventricular size (III and IV), intracerebral haematoma size, and subarachnoid haemorrhage	ICP monitored by subarachnoid catheter. No data on later development of intracranial hypertension
Eisenberg et al. [8]	753	Multi-centre, retrospective analysis of prospective observational data on prediction of abnormal ICP	Mod	For first 72 h, strongest (p < 0.001) independent predictors of percent of monitored time that ICP > 20 mmHg were abnormal mesencephalic cisterns, midline shift, and subarachnoid blood. For ICP occurrences >20 mmHg, the strongest (p < 0.001) was cisternal compression, with age, midline shift, and intraventricular blood reaching p < 0.05	Used only end-hour ICP values
Kishore et al. [9]	137 (47 with normal admission CT)	Single-centre, retrospective observational analysis of correlation of final Marshall CT classification with ICP course	Low	Elevated ICP was present in ≥55 % of patients with intra- or extra-axial haematomas. 17 % of patients with normal admission CT imaging had ICP > 20 mmHg	Used only intermittent ICP measurements. Did not separate out patients with persistently normal CT imaging
Narayan et al., 1982 [5]	226	Single-centre retrospective observational study of predictors of intracranial hypertension	Low	Association with intracranial hypertension for abnormal admission CT = 53–63 %; for normal admission CT = 13 %. 2+ of predictive variables* with normal CT had 60 % incidence (*age > 40 years, systolic blood pressure ≤90 mmHg, or motor posturing)	No magnitude for ICP elevation. No prospective verification of normal CT model. Examined only admission CT imaging. Used only end-hour ICP values
Miller et al., 2004 [10]	82	Single-centre retrospective observational study modeling CT characteristics as predictors of intracranial hypertension	Low	Initial CT ventricle size, basilar cisterns, sulcal size, transfalcine herniation, and gray/white differentiation were associated with, but not predictive of intracranial hypertension	Non-standardised CT variable grading system. Small sample size for modeling. No magnitude for ICP elevation
Lobato et al., 1983 [11]	277	Single-centre, retrospective observational study of outcome of monitored patients	Low	Normal CT imaging post evacuation of extracerebral haematomas did not have ICP problems; normal, non-operative scans had 15 % incidence of intracranial hypertension, none severe (>35 mmHg). Other combinations of contusions or brain swelling had much higher incidences	No multivariate statistics for ICP. Examined only admission CT imaging
Poca et al. [12]	94	Single-centre, retrospective analysis of prospective observational data on correlation of final Marshall CT classification with ICP course	Low	Development of intracranial hypertension by final Marshall Classification: DI I = 0 %; DI II = 28.6 % (10 % uncontrollable); DI III = 63.2 % (1/3 uncontrollable); DI IV = 100 % (all uncontrollable); EML = 65.2 % (1/2 uncontrollable); NEML = 84.6 % (1/2 uncontrollable)	Did not separately report admission CT class as predictive of ICP course. Used only intermittent ICP measurements
Miller et al. [59]	225	Single-centre, retrospective observational study of ICP and outcome of consecutive sTBI patients	Low	Less than 25 % incidence of persistent ICP > 20 mmHg in patients with normal admission CT imaging	Little detail on patients with normal admission CT
Holliday et al. [106]	17	Single-centre, retrospective observational study of ICP course of patients with normal admission CT imaging	Low	86 % of their patients with normal admission CT and ICP > 25 mmHg had associated pulmonary complications. Patients with “normal” admission CT did not develop intracranial hypertension	Examined only admission CT imaging. Implications of “secondary” ICP elevation unclear. Normal CT could include cisternal compression, slit ventricles
Lobato et al. [107]	46 patients (39 monitored)	Single-centre, retrospective observational study of ICP course of patients with repeatedly normal CT imaging	Low	No patient with persistently normal admission CT had sustained intracranial hypertension. Within the first 24 h, 10 % had transient ICP elevation below 25 mmHg	Examined only admission CT imaging.
O’Sullivan et al. [108]	22 patients (8 with highresolution monitoring)	Single-centre, retrospective observational analysis of ICP course in patients without signs of ICP elevation on admission CT	Low	88 % had intracranial hypertension (ICP > 20 mmHg), severe (protracted period ≥ 30 mmHg) in 62 %	Primary ICP monitoring by subdural systems
Lee et al. [13]	36	Single-centre, retrospective observational analysis of ICP course in patients with CT diagnosis of DAI	Low	28 % had no ICP > 20 mmHg, 47 % had ICP values 21–30 mmHg and 25 % had ICP values >30 mmHg. Only 1 patient (3 %) underwent treatment	Used only intermittent ICP measurements. Incomplete description of management methods