703 - Assessing Cerebrovascular Reactivity to Carbon Dioxide Tension Using Near-Infrared Spectroscopy in Neonates with Congenital Diaphragmatic Hernia

Publication Number: 703.3713

Sheetal Sriraman, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Toni Iurcotta, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Joseph R. Isler, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Rakesh Sahni, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States

Background: Critically ill newborns are at risk of brain injury due to cerebrovascular disturbances. The risk is amplified in cases of impaired autoregulation that accompanies hypercapnia-associated increases in cerebral blood flow. A cerebral hemodynamic monitoring system such as near-infrared spectroscopy (NIRS) has the potential to identify and guide targeted interventions.

Objective: To evaluate changes in NIRS-derived cerebral tissue oxygen saturation (C-SO2) during variations in arterial carbon dioxide tension (PaCO2) resulting from acute respiratory failure in neonates with Congenital Diaphragmatic Hernia (CDH).

Design/Methods: A retrospective review of NIRS C-SO2 values (collected every 5 seconds) using the INVOS-7100 Regional Oximetry Monitor (Medtronic, Boulder, CO) and PaCO2 values obtained from clinically indicated arterial blood gases was performed in four infants with CDH and acute respiratory failure during the first 48 hours of life. The median gestational age at enrollment was 37 weeks and the median weight was 2612 g. No brain abnormalities were noted on the cranial ultrasounds of these infants. The effect of changes in PaCO2 on corresponding C-SO2 values across all infants was estimated using linear regression analysis.

Results: Figure 1 displays the overlapping variations in trends of continuously collected cerebrovascular reactivity (C-SO2 in blue) and the corresponding intermittently measured PaCO2 (in red) for an index infant who was mechanically ventilated for acute respiratory failure. Across all infants, increases in PaCO2 were associated with increasing C-SO2 values (p < 0.0001, R2 = 0.65) (figure 2). C-SO2 increased by 0.62% with each mm Hg increase in PaCO2.

Conclusion(s): As expected, the NIRS device detected PaCO2-induced changes in C-SO2, reflecting non-invasive estimates of cerebrovascular reactivity to carbon dioxide tension in the arterial blood. These data suggest that continuous monitoring of cerebral hemodynamics with NIRS can potentially guide individualized care and targeted interventions to reduce the risk of carbon dioxide induced cerebral injury.

Cerebrovascular reactivity to carbon dioxide tension in newborns with congenital diaphragmatic hernia


Relationship between arterial carbon dioxide tension and cerebral oxygenation measured using near-infrared spectroscopy