Artikel
Analysis of the value of the pulsatility index (PI) of the transcranial Doppler sonography as predictor of intracranial pressure
Analyse der Wertigkeit des Pulsatilitätsindexes (PI) der transkraniellen Dopplersonographie zur Vorhersage des intrakraniellen Druckes
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Autoren
Veröffentlicht: | 23. April 2004 |
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Gliederung
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Objective
The pulsatility index (PI) of transcranial Doppler sonography is reported to correlate with the intracranial pressure (ICP). Since the PI can be investigated non-invasively, this capability seems clinically important. However, there have been examples of failure of the prediction of the PI. Therefore, it was the aim of this study to prospectively examine the relation between PI and ICP and the predictive value of the PI regarding ICP.
Methods
A prospective study was designed. Patients with intraparenchymatous ICP (Camino 110-4b) probes or fluid-coupled ICP transducers (Codman EDS II) were examined by TCD and the PI was calculated daily for the period of the ICP monitoring. Inclusion criterias: Age 18-85 years, patients with head injuries, intracerebral bleeds or subarachnoidal haemorrhage (SAH). Exclusion criterias: known cardiovascular abnormalities or vasospasm (Vmean> 100cm/s). Both middle cerebral arteries were examined by transcranial Doppler insonation. Velocity parameters measured included the peak systolic (S), end-diastolic (D) and time mean (M) velocities, from which the pulsatility index could be calculated: S-D/M. A regression analysis of the different parameters was performed. In addition to the Goodness-of-Fit test, the Shapiro-Wilk test was used.
Results
Fourty-nine patients were examined. The mean age was 49,5 years. Eighteen patients presented with a head injury, 10 with an intracranial bleeding, 17 patients with a SAH and 4 with other pathologies. 372 TCD examinations were performed. ICP values ranged from 0-52 mmHg, the mean ICP was 11,2 mmHg. Intraparenchymatous ICP probes and fluid-coupled transducers were evaluated separately but the results were similar. The correlation of the PI and corresponding ICP revealed correlation coefficients of 0,6 (Camino) and 0,5 (fluid-coupled transducer). These results were statistically significant (fluid coupled probe: p<0,0001), (Camino: p<0,01). The PI did not have any predictive value regarding ICP from these data.
Conclusions
The PI of transcranial Doppler sonography is not a reliable predictor of the intracranial pressure and can not be recommended for clinical use.