Age-related cerebrovascular carbon dioxide reactivity in children with ventricular septal defect younger than 3 years.

BACKGROUND Impaired cerebrovascular reactivity to carbon dioxide wasproposed to contribute to neurological morbidity in children undergoing cardiac surgery.Theobjective of this study was to assess carbon dioxide reactivityand regional cerebral oxygensaturationin children younger than 3 years. METHODS This study enrolled children younger than 3 years undergoing ventricular septal defect repair. The cohort was divided into three age groups: younger than 6 months, 6-12 months and 12-36 months. Under steady-state anesthesia, carbon dioxide reactivity was calculated by measuring changes in middle cerebral artery blood flow velocityusing transcranial Dopplersonography.Regional cerebral oxygen saturation changes were measured by near-infrared spectroscopy while end-tidal carbon dioxide pressure was adjusted from 30 to 45 mmHg. RESULTS Carbon dioxide reactivityshowed a statistically significant increasing relationship with age (younger than 6 months group: 4.42%±2.73%, 6-12 months group: 5.86%±1.91%, 12-36 months group: 7.58%±1.49%; p<0.001). Regional cerebral oxygen saturation showed a statistically significantincreasing relationshipwith age (younger than 6 months group: 65%±6%, 6-12 months group: 68%±5%, 12-36 months group: 70%±5%; p=0.027). Regional cerebral oxygen saturationshowed a statistically significant increasing relationship with end-tidal carbon dioxide pressure in all children (p<0.001). CONCLUSION Abnormal carbon dioxide reactivity is prevalent in children younger than 3 years and the degreevaries according to age.