Clinical significance of assessing cerebral blood volume by time domain near-infrared spectroscopy in children with congenital heart disease.

BACKGROUND Despite providing cerebral tissue oxygen saturation (StO2), the lack of quantitative information for continuous wave near-infrared spectroscopy (CW-NIRS) is an obstacle in evaluating cerebral hemodynamic conditions. Time-domain NIRS (TD-NIRS) provides both StO2 and cerebral blood volume (CBV), and has recently become clinically available. AIM To investigate if the additional monitoring of CBV by TD-NIRS facilitates the understanding of cerebral hemodynamic conditions in patients with congenital heart disease (CHD). METHODS Preoperative TD-NIRS values were retrospectively reviewed in patients who underwent a cardiac surgery or catheter examination. We compared the values between patients with single and two ventricles (SV and 2V respectively). Moreover, we investigated the association of these values with the demographic and clinical variables. RESULTS There was no significant difference in StO2 between SV and 2V groups (median: 59.9 vs. 54.4, median difference [95% CI]: - 4.06 [- 9.90 - 2.90], p=0.37). However, CBV was significantly higher in the SV group (median: 4.68 vs. 2.84, median difference [95% CI]: -2.01 [-2.88 - -1.06], p<0.001). Spearman's rank correlation analysis demonstrated an association between StO2 and postmenstrual age (PMA) (r=0.35, p=0.03). In contrast, CBV was correlated with SV physiology (r=0.62, p<0.001), PMA (r=0.74, p<0.001), central venous pressure (r=0.38, p=0.02), and SaO2 (r=- 0.38, p=0.02). The multivariable regression analysis identified the PMA, SV physiology, and SaO2 as independent factors associated with CBV. In the logistic analysis, CBV was identified as a significant predictor of unfavorable conditions. CONCLUSION CBV monitoring detected differences in cerebral hemodynamic conditions, related to the age and the type of ventricle physiologies. However, the differences were not apparent in StO2. The additional monitoring of CBV by TD-NIRS would facilitate a better understanding of cerebral hemodynamic conditions in patients with CHD.