Transcranial Doppler monitoring in severe brain damage: relationships between intracranial haemodynamics, brain dysfunction and outcome.

Transcranial Doppler (TCD) monitoring in the middle cerebral (MCA) and common carotid arteries (CCA) was studied in 105 comatose patients with severe brain damage. TCD-measured velocity waveforms in the MCA were evaluated in relation to loss of cerebral function as assessed by EEG and compressed spectral arrays, loss of brain stem function as measured by somatosensory and auditory evoked potentials, loss of all brain function and the clinical outcome. The velocity waveforms exhibited six patterns: continuous forward flow (FF); diastolic no flow (NF); diastolic reverse flow with (RF) or without (DRF) diastolic FF; brief systolic FF (SFF); and undetectable (U). In the 58 fatal cases, the appearance of RF/DRF or SFF in the MCA more often preceded loss of brain stem function than loss of cerebral function. A U pattern in the MCA, which was confirmed by loss of FF in the CCA, was correlated with loss of brain stem function. Only one of the 47 survivors showed DRF in the MCA. No patients in whom SFF or U was observed in the MCA survived. Therefore the presence of these patterns is reliably predictive of brain death. Intracranial diastolic reverse flow (DRF), however, indicates imminent loss of brain function and the need for prompt resuscitative measures.