Cerebral blood flow during cardiopulmonary bypass in pediatric cardiac surgery: the role of transcranial Doppler--a systematic review of the literature.
BACKGROUND
Transcranial Doppler Ultrasound (TCD) is a sensitive, real time tool for monitoring cerebral blood flow velocity (CBFV). This technique is fast, accurate, reproducible and noninvasive. In the setting of congenital heart surgery, TCD finds application in the evaluation of cerebral blood flow variations during cardiopulmonary bypass (CPB).


METHODS
We performed a search on human studies published on the MEDLINE using the keyword "trans cranial Doppler" crossed with "pediatric cardiac surgery" AND "cardio pulmonary by pass", OR deep hypothermic cardiac arrest", OR "neurological monitoring".


CONCLUSIONS
Current scientific evidence suggests a good correlation between changes in cbral blood flow and mean cerebral artery (MCA) blood flow velocity. The introduction of Doppler technology has allowed an accurate monitorization of cerebral blood flow (CBF) during circulatory arrest and low-flow CPB. TCD has also been utilized in detecting cerebral emboli, improper cannulation or cross clamping of aortic arch vessels. Limitations of TCD routine utilization are represented by the need of a learning curve and some experience by the operators, as well as the need of implementing CBF informations with, for example, data on brain tissue oxygen delivery and consumption.


CONCLUSIONS
In this light, TCD plays an essential role in multimodal neurological monitorization during CPB (Near Infrared Spectroscopy, TCD, processed electro encephalography) that, according to recent studies, can help to significantly improve neurological outcome after cardiac surgery in neonates and pediatric patients.
Polito
Angelo
A
Department of Pediatric Cardiology and Cardiac Surgery, Bambino Gesù Hospital, Rome, Italy. angpolito@hotmail.com <angpolito@hotmail.com>
Ricci
Zaccaria
Z
Di Chiara
Luca
L
Giorni
Chiara
C
Iacoella
Claudia
C
Sanders
Stephen P
SP
Picardo
Sergio
S
D001013:Aorta, Thoracic / Q000601:surgery; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation; D002648:Child; D006324:Heart Arrest, Induced; D006801:Humans; D007036:Hypothermia, Induced; D007231:Infant, Newborn; D016343:Monitoring, Intraoperative; D019651:Plastic Surgery Procedures; D017585:Ultrasonography, Doppler, Transcranial