Accuracy of intracranial pressure monitoring: systematic review and meta-analysis

Table 1 Main features of the studies included in the meta-analysis

	Author/year of publication	Probe 1	Probe 2	Probe placement	Patients (n)	Calibration/zeroing^a	Mean difference	Standard deviation	Correlation	Data^b
Group 1
1	Schickner 1992 [4]	Camino	VFC	P–V	10	+/+	9.20	7.80	NA	Reported
2	Chambers 1993 [21]	Camino	VFC	V–V	10	+/+ ^(EAM)	1.43	2.26	0.98	Calculated
3	Statham 1993 [22]	Camino	VFC	P–V	11	+/+	2.73	4.22	0.98	Reported
4	Gopinath 1995 [23]	Codman	VFC	V–V	25	+/+	0.50	2.60	0.97	Reported
5	Signorini 1998-2 [24]	Codman	VFC	P–V	2	+/+ ^(EAM)	1.81	3.75	NA	Calculated
6	Chambers 2001 [25]	Spiegelberg	VFC	P–V	11	+/+ ^(EAM)	0.10	4.99	NA	Reported
7	Koskinen 2005 [8]	Codman	VFC	P–V	22	+/+ ^(EAM)	1.20	3.32	0.79	Reported
8	Lescot 2011-1 [26]	Pressio	VFC	P–V	15	+/+ ^(EAM)	–0.60	3.83	NA	Reported
9	Lescot 2011-2 [26]	Codman	VFC	P–V	15	+/+ ^(EAM)	0.30	3.52	NA	Reported
10	Eide 2012-2 [18]	Codman	VFC	P–V	5	NA/NA	4.52	13.97	NA	Calculated
Group 2
11	Signorini 1998-1 [24]	Codman	Camino	P–P	5	+	1.58	3.36	NA	Calculated
12	Sahuquillo 1999-1 [2]	Camino	Camino	P–P	33	NA	1.80	1.10	0.95	Reported
13	Sahuquillo 1999-2 [2]	Camino	Camino	P–P	16	NA	7.50	6.40	0.85	Reported
14	Eide 2012-1 [18]	Codman	Codman	P–P	5	NA	0.64	5.59	NA	Calculated
15	Eide 2012-3 [18]	Codman	Spiegelberg	P–P	7	+	0.70	2.63	NA	Calculated

Studies comparing simultaneous readings from at least two catheters for intracranial pressure monitoring classified depending on the reported use (Group 1) or not use (Group 2) of a reference standard (i.e.VFC) and reported in chronological order. Some papers reported more than one study; four are cited repeatedly. In two studies a single catheter was placed in the ventricles (V-V). This gave a typical reading through a fluid-filled system and a simultaneous measurement through a solid transducer at the tip
^aDescription of calibration (of the solid probe) and zeroing (of the ventricular fluid-filled catheter). (+) Calibration or zeroing is reported, (++) both calibration and zeroing are reported; NA information on calibration and zeroing maneuvers not available, ^(EAM) zeroing described at the external auditory meatus
^bIndicates how the mean intracranial pressure differences between probes and standard deviations were determined (see Methods)
NA Not Available, P Parenchymal, V Ventricular, VFC Ventricular Fluid-Coupled catheter with external transducer

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