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Transcranial pulsed Doppler ultrasound findings in brain stem death
F J Kirkham1, S D Levin, T S Padayachee
1Department of Paediatrics, Guy's Hospital, London UK.
Abstract:
Data are presented from transcranial insonation of the middle cerebral artery (MCA) performed at intervals in 23 unconscious children for whom the outcome was subsequently poor. Once an MCA signal had been observed over a 30 minute period with time averaged velocity less than 10 cm s-1 and/or a direction of flow index, DFI, defined as 1 minus the ratio of reverse to forward flow of less than 0.8, recovery to forward flow throughout diastole was never observed and no patient recovered brain stem reflexes. Recovery of forward flow in diastole, and of brain stem function, was seen in cases with time averaged MCA velocity in the range 10 to 25 cm s-1 and with reverse flow but a DFI of greater than 0.8 for short periods of time. All but one of the 13 children fulfilling clinical criteria for brain stem death had MCA signals with time averaged velocity of less than 10 cm/s and DFI of less than 0.8. This type of signal was not observed in five children who were left in a persistent vegetative state.
Insights
Transcranial Doppler ultrasound in unconscious children can predict outcomes. A low middle cerebral artery (MCA) velocity and direction of flow index (DFI) indicate poor prognosis, with no recovery of brainstem reflexes observed.
Area of Science:
- Neurosonology
- Pediatric Neurology
- Critical Care Medicine
Background:
- Assessing neurological prognosis in unconscious children is challenging.
- Transcranial Doppler (TCD) ultrasound is a non-invasive tool for evaluating cerebral blood flow.
Purpose of the Study:
- To investigate the utility of middle cerebral artery (MCA) blood flow parameters in predicting outcomes in unconscious children.
- To correlate TCD findings with clinical outcomes, including brainstem reflexes and persistent vegetative state.
Main Methods:
- Transcranial insonation of the MCA was performed in 23 unconscious children.
- Key parameters analyzed included time-averaged velocity (cm/s) and direction of flow index (DFI).
- Correlation of TCD findings with subsequent clinical outcomes was assessed.
Main Results:
- A sustained MCA signal with time-averaged velocity < 10 cm/s and/or DFI < 0.8 was associated with no recovery of brainstem reflexes.
- Recovery of diastolic forward flow and brainstem function was observed in children with MCA velocity between 10-25 cm/s and DFI > 0.8.
- 12 of 13 children meeting criteria for brainstem death exhibited MCA velocity < 10 cm/s and DFI < 0.8.
Conclusions:
- Low MCA time-averaged velocity and DFI are strong indicators of poor neurological outcome in unconscious children.
- TCD parameters can aid in differentiating brainstem death from persistent vegetative states.
- Transcranial Doppler ultrasound is a valuable tool for prognostication in critically ill pediatric patients.