Transcranial Doppler monitoring of microembolic signals during extracorporeal membrane oxygenation in sheep

Objective To evaluate the transcranial Doppler (TCD) monitoring of microembolic signals (MES) during extracorporeal membrane oxygenation (ECMO) and to explore the relationship between the number of MES and the neurological outcome. Methods Using American Medsonics CDS TCD machine to detect MES continuously during ECMO process in 14 sheep. The cerebral morphological and pathological examinations was carried out in 9 of 14 sheep. Results (1) The MES were easily detected both at the onset of ECMO and at the pump increasing phase. The most MES was air bubble signals. (2) There was no abnormality in brains of 9 sheep by the gross observation. Under the microscopy, the bilateral cerebral tissue structures were normal except the brain malacia was discovered at some areas of brains in 4 sheep. (3) No significant correlation between the whole numbers of MES and brain malacia was found. Conclusion TCD monitoring of MES during ECMO was successful, and may help to improve the quality of the ECMO operations and to decrease the potentially harmful embolization during ECMO. Key words: Ultrasonography, Doppler, transcranial; Cerebral embolism and thrombosis; Extracorporeal membrane oxygenation; Sheep