Background: The effects of aortovenous cannulations for pediatric cardiopulmonary bypass on cerebral blood flow velocity (CBFV) and electroencephalography (EEG) were evaluated.
Methods: CBFV and EEG were continuously recorded before (baseline), during, and after cannulations until initiation of cooling (mean +/- 95% confidence interval). Vasopressors and/or volume replacement were administered if mean arterial pressure (MAP) decreased below 35 mm Hg. Cannulation-related EEG slowing was used as a criterion for electrocortical alteration.
Results: We studied 124 children (3 days to 17 years of age). Aortic and venous cannulations decreased mean CBFV by 10+/-3% and 13+/-4%, respectively, from baseline (p < 0.001). MAP diminished (p < 0.01) by 8+/-3% and 12+/-4%, respectively, from precannulation values (53+/-2 mm Hg). Right atrial cannulation, which was often chosen because the patient was hemodynamically unstable, was more frequently associated with pharmacologic intervention when compared with superior vena cava (SVC) cannulation (p < 0.01). Transient 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 more frequent EEG alterations (p = 0.04). Patients requiring intervention were younger (p < 0.01) and had longer hospital stay (p < 0.01) than those without 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.