Cerebral Blood Flow Monitoring for Instant Display of Circulatory Events During Cardiac Surgery

Background: Neurodevelopmental delay remains a concern in children with congenital heart disease. Although the etiology is multifactorial, brain perfusion is central, and better neuromonitoring is warranted. NIRS (Near-Infrared Spectroscopy) is commonly used to monitor cerebral oxygenation during and after cardiac surgery. NeoDoppler is a new technique for continuous monitoring of cerebral perfusion. A small ultrasound probe placed above the anterior fontanelle measures blood flow velocities in the brain. The Doppler spectrum is displayed in real-time at several depths simultaneously. Case Description: A newborn child was diagnosed with infradiafragmatic TAPVD (total anomalous pulmonary venous drainage). A retrocardiac surgical approach with deep hypothermia circulatory arrest was used. As seen in Figure 1, cardiopulmonary bypass (CPB) was temporarily ceased at 10.14. This was instantly displayed with NeoDoppler, whereas simultaneous NIRS-monitoring took a total of 23 minutes and 56 seconds to reach the alarm threshold of 40%. Shortly following circulatory arrest the NeoDoppler curve shows a brief period of cerebral hyperflow. This is followed by a phase of hypoperfusion. This is partly due to increased cerebral vascular resistance, a protective mechanism described during perinatal asphyxia. Conclusion: NeoDoppler instantaneously displayed changes in cerebral blood flow when CPB was ceased. It is a promising method of monitoring cerebral perfusion in neonates during cardiac surgery.