Impaired cerebral autoregulation in preoperative newborn infants with congenital heart disease

Abstract

Objectives: To characterize cerebral autoregulation (CA) in preoperative newborn infants with congenital heart disease (CHD).

Methods: This was a prospective, pilot study of term newborns with CHD who required intensive care. Continuous mean arterial blood pressure (MAP), cerebral tissue oxygen saturation (S_CTO₂) via near-infrared spectroscopy, and arterial oxygen saturation (SaO₂) were collected. Significant low-frequency coherence between MAP and S_CTO₂ was used to define impaired CA in 20-minute epochs. Cerebral fractional tissue oxygen extraction (FTOE) = (SaO₂ - S_CTO₂)/SaO₂ was calculated. Spearman's and rank bi-serial correlations and logistic linear models accounting for multiple measures were used to identify associations with impaired CA and coherence.

Results: Twenty-four term neonates were evaluated for 23.4 ± 1.8 hours starting the first day of life. Periods of SaO₂ variability >5% were excluded, leaving 63 ± 10 epochs per subject, 1515 total for analysis. All subjects demonstrated periods of abnormal CA, mean 15.3% ± 12.8% of time studied. Significant associations with impaired CA per epoch included greater FTOE (P = .02) and lack of sedation (P = .02), and associations with coherence included greater FTOE (P = .03), lack of sedation (P = .03), lower MAP (P = .006), and lower hemoglobin (P = .02).

Conclusions: Term newborns with CHD display time-varying CA abnormalities. Associations seen between abnormal CA and greater FTOE, lack of sedation, and lower hemoglobin suggest that impaired oxygen delivery and increased cerebral metabolic demand may overwhelm autoregulatory capacity in these infants. Further studies are needed to determine the significance of impaired CA in this population.

Keywords: cerebral autoregulation; coherence; congenital; heart defects; near-infrared spectroscopy; neonate; pressure passive.