Marina Mir

OBJECTIVES: To describe temporal trends and instantaneous relationships between middle cerebral artery (MCA) cerebral blood flow velocity, cerebral oxygen saturation (Csat), cerebral fractional tissue oxygen extraction (cFTOE), and systemic arteriovenous oxygen difference (AV o ₂ ) during the first 24 hours following congenital heart disease (CHD) surgery requiring cardiopulmonary bypass (CPB). DESIGN: Prospective observational study conducted from August 2021 to June 2022. SETTING: Single-center pediatric cardiac ICU in Canada. PATIENTS: Fifteen ventilated neonates and infants admitted to the PICU following CHD surgery requiring CPB. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Bilateral transcranial Doppler (TCD) assessments of the MCA were performed at seven predefined time points during the first 24 hours following CPB, with time 0 defined as the end of CPB. A total of 87 simultaneous measurements of systemic oxygen saturation, Csat, TCD-derived parameters, and AV o ₂ were analyzed. The nadir in MCA velocities occurred at a mean of 9.3 hours ( sd , 1.7 hr) post-CPB and coincided with the lowest Csat and the highest AV o ₂ difference and cFTOE. Lower MCA mean velocities were associated with higher AV o ₂ difference and increased cFTOE. CONCLUSIONS: In neonates and infants following CPB, MCA velocities reach its lowest point approximately 9 hours post-CPB, coinciding with the highest AV o ₂ difference and previously published nadir of cardiac output. These findings could suggest a period of relative cerebral hypoperfusion. Future studies should evaluate whether targeted interventions guided by multimodal cerebral monitoring can mitigate the risk of acute and long-term brain injury in this vulnerable population.

Introduction: Congenital heart disease (CHD) is one of the most common birth defects. Cerebral (cStO2) and renal (rStO2) saturations measured by near-infrared spectroscopy (NIRS) and the corresponding fractional tissue oxygen extraction (FTOE) during the first week of life in neonates with CHD are described comparing those with and without diastolic steal. Methods: Single-center prospective cohort study (Montreal Children’s Hospital, Montreal, QC, Canada) was conducted, including neonates >34 weeks with CHD without chromosomal anomalies. CStO2/rStO2 was monitored from enrollment until day 7 of life. FTOE was calculated using systemic saturation (SpO2) as [SpO2 − (cStO2 or rStO2)]/SpO2. Daily echocardiography was performed during the monitoring period. Random mixed-effects models were constructed to assess the association between NIRS/FTOE and the presence of retrograde postductal aortic flow on last available echocardiography. Results: Among 49 included neonates, 27 (55%) exhibited retrograde flow in the postductal aorta on the last day of monitoring. Prostaglandin exposure was 100% in the retrograde group vs. 27% in the non-retrograde group. CStO2/rStO2 progressively declined in neonates with CHD over the first week of life. Retrograde aortic flow was associated with negative cStO2 (β = −9.1%, 95% CI [−14.3; −3.8]) and rStO2 (β = −8.4%, 95% CI [−14.5; −2.3]). Cerebral FTOE was lower in the non-retrograde group, while renal FTOE was similar between groups. Conclusion: During the first week of life, neonates with CHD who displayed retrograde aortic flow exhibited lower cStO2 and rStO2 as well as higher cerebral FTOE. Future studies should evaluate whether these markers in neonates with CHD are modifiable factors that could influence cerebral or renal injury when addressed.

Introduction: The aim of the study was to explore the relationship between near-infrared spectroscopy parameters (cerebral saturation [CSat] and corresponding cerebral fractional tissue oxygen extraction [cFTOE]) with resistive (RI) and pulsatility indices (PI) of the anterior cerebral artery (ACA) obtained simultaneously in neonates with congenital heart defect (CHD) during the first week of life. Methods: Prospective observational study on neonates ≥35 weeks with CHD was conducted. Cerebral FTOE was based on concomitant pre-ductal oxygen saturation (SpO2) during CSat measurement. ACA was assessed via Doppler ultrasound (US). Continuous CSat/SpO2 monitoring was collected during the first week of life. Daily ACA Doppler was obtained from day 1–7. Results: A total of 142 concomitant measurements of NIRS and US parameters during the first week of life were collected in 34 neonates with various CHD. Mixed effect models showed significant association between CSat/cFTOE and time-corresponding RI-ACA (p = 0.02 and 0.005) and PI-ACA (p = 0.006 and 0.002), respectively. A 0.1-point increase in RI was associated to a 2.3% decrease in CSat and a 3-point increase in cFTOE. A 0.1-point increase in PI was associated to a 0.9% decrease in CSat and 1.1-point increase in cFTOE. Conclusions: In neonates with CHD during their first week of life, lower CSat and higher cerebral FTOE were associated with elevated RI and PI values of the ACA obtained simultaneously. Future research should assess whether a multimodal bedside approach to monitoring cerebrovascular hemodynamics can facilitate early detection of cerebral hypoperfusion and prevent brain injury, as well as adverse neurodevelopmental outcomes in this vulnerable population.