Résumé
Background: The use of TCD during paediatric cardiac surgery can help in early detection of cerebral blood flow velocity. The aim of this study was to describe the changes in cerebral blood flow velocity and to explore the relationship of such changes with different haemdynamic and cardiopulmonary bypass parameters in children undergoing open heart surgery
Methods: Sixteen patients from 1-12 years undergoing correction for congenital heart defects were included in this study. Two-channel transcranial Doppler system [Multi-Dop T[2] / DWL, Elektronische System GmbHGermany] were used for measuring mean cerebral blood flow velocity in middle cerebral artery after induction [basal], after sternotomy, during aortic cannulation, during stable CPB [10 min. after start of bypass], during rewarming, after weaning from CPB and after skin closure. Concomitant measurements of mean arterial blood pressure, arterial CO[2], haematorcrite, temperature and arterial oxygen tension were recorded with cerebral blood flow velocity. One way analysis of variance was used to study the changes in cerebral blood flow velocity and multiple regression analysis to predict different factors that can affect cerebral blood flow velocity
Results: A significant reduction in mean cerebral blood flow velocity was detected during stable CPB, during rewarming and after CPB compared with base line value. Before CPB, cerebral blood flow was directly dependent on the age and PaCO[2], while during rewarming it was only directly dependent on mean arterial blood pressure [P = 0.036]. However, an inverse association was found between PaO[2] and CBFV after CPB
Conclusion: These results suggest that cerebral blood flow velocity was reduced during hypothermic CPB, and it was only affected by mean arterial blood pressure during rewarming