Cerebral vascular effects of aortovenous cannulations for pediatric cardiopulmonary bypass

Background. The effects of aortovenous cannulations for pediatric cardiopul monary bypass on cerebral blood flow velocity (CBFV) and electroencephalogr aphy (EEC) were evaluated. Methods. CBFV and EEG were continuously recorded before (baseline), during, and after cannulations until initiation of cooling (mean +/- 95% confidenc e interval). Vasopressors and/or volume replacement were administered if me an arterial pressure (MAP) decreased below 35 mm Hg. Cannulation-related EE C slowing was used as a criterion for electrocortical alteration. Results. We studied 124 children (3 days to 17 years of age). Aortic and Ve nous cannulations decreased mean CBFV by 10 +/- 3% and 13 +/- 4%, respectiv ely, from baseline (p < 0.001). MAP diminished (p < 0.01) by 8 +/- 3% and 1 2 +/- 4%, respectively, from precannulation values (53 +/- 2 mm Hg). Right atrial cannulation, which was often chosen because the patient was hemodyna mically unstable, was more frequently associated with pharmacologic interve ntion when compared with superior vena cava (SVC) cannulation (p < 0.01). T ransient EEG alterations (n = 20) were associated with persistently low MAP (< 30 mm Hg), low CBFV (< 69%), and aortic (n = 4) or SVC (n = 7) cannula malposition. Infants with right atrial cannulation and intervention had mor e frequent EEG alterations (p = 0.04). Patients requiring intervention were younger (p < 0.01) and had longer hospital stay (p < 0.01) than those with out intervention. Conclusions. Cerebral effects of cannulations are greater in young infants. This was found to be associated with low MAP during heart manipulation or consequence of cannula malpositions. (C) 2000 by The Society of Thoracic Su rgeons.