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Correlation of transcranial doppler (TCD) parameters with intracranial pressure (ICP)

Introduction

Intracranial Pressure (ICP) is an important factor in providing adequate cerebral blood flow and oxygen delivery to the brain. The use of ICP monitoring techniques has a lot of surgical risk factors, it is expensive, and is not readily available. On the other hand, transcranial doppler ultrasonography (TCD), is a non invasive bedside technique, which measures the velocities of the great cerebral arteries and may detect cerebral ischemia. The aim of our study was to test the hypothesis that, in head trauma patients, a correlation exists between ICP and TCD findings.

Methods

59 patients (37 ± 19 years) with severe head trauma (Glasgow coma scale below 8) were included in our study. We assessed ICP and jugular bulb venous oxygen saturation (SjvO2). ALL patients were under mechanical ventilation and ICP measurements were carried out using an intracerehral or intraventricular catheter. Intracerebral hypertension management was based on CPP and SjvO2 findings. During the first three crucial ICU days, multiple TCD examinations (total 108) were performed. Simultaneous measurements of ICP, CPP, SjvO2, as well as TCD values were recorded. The TCD parameters used were: Maximum velocity (Vmax), minimum velocity (Vmin), time average mean velocity (tamV), and pulsatility index (PI). [PI = (Vmax-Vmin)/tamV]. The findings obtained from TCD were compared with ICP using the multiple regression analysis method.

Results

In our study, the best correlation was demonstrated between ICP and the PI index as well as Vmin. The correlation of PI with ICP was exponential (P = 0.028), while the correlation of Vmin with CPP was a linear regression (P = 0.022). Using the multiple regression method, the elevation of ICP was demonstrated by the PI index in only 10 per cent (R2 = 0.10934). With this same method, Vmin was unable to provide more information.

Conclusion

Pulsatility index (PI) can predict the elevation of ICP. However, this is not applicable in all cases. At a prior study [1], we found that the reduction of CPP was demonstrated by the PI index in 50% (R2 = 0.50) and we suggested that this was due to factors which can influence the pulsatile arterial waveform (impaired vascular contractility, tachycardia, etc.). At this study we found that the elevation of ICP is demonstrated by the PI index in only 10% (R2 = 0.10). We suggest that this is due to the suppression of the cerebral autoregulation at head trauma patients.

References

  1. 11th Annual Congress Of The European Society Of Intensive Care Medicine. Stockholm, Sweden6–9September 1998.

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Vakalos, A., Matamis, D., Rodini, I. et al. Correlation of transcranial doppler (TCD) parameters with intracranial pressure (ICP). Crit Care 3 (Suppl 1), P218 (2000). https://doi.org/10.1186/cc591

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  • DOI: https://doi.org/10.1186/cc591

Keywords

  • Pulsatility Index
  • Cerebral Autoregulation
  • Jugular Bulb
  • Transcranial Doppler Ultrasonography
  • Severe Head Trauma