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Updated: Aug 17, 2026
Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants
Published on: March 14, 2013
High flow rates during modified ultrafiltration decrease cerebral blood flow velocity and venous oxygen saturation in
Rosendo A Rodriguez1, Marc Ruel, Lothar Broecker
1Department of Anesthesiology, Cardiac Division, Ottawa, Ontario, Canada. rrodriguez@ottawaheart.ca
Insights
High ultrafiltration blood flow rates reduce cerebral circulation in infants. Lower flow rates during modified ultrafiltration are safer for maintaining cerebral blood flow and oxygenation in pediatric patients.
Area of Science:
- Pediatric Cardiology
- Neonatal Intensive Care
- Cerebral Hemodynamics
Background:
- Intracranial hemodynamic effects of modified ultrafiltration in children remain uncharacterized.
- Investigated the impact of varying blood flow rates during modified ultrafiltration on cerebral hemodynamics in pediatric patients.
Purpose of the Study:
- To assess the effects of different blood flow rates during modified ultrafiltration on cerebral hemodynamics in children.
- To compare hemodynamic changes in infants weighing below and above 10 kg.
Main Methods:
- Studied 31 children undergoing cardiopulmonary bypass, categorized by weight (< or = 10 kg, n=21; >10 kg, n=10).
- Measured middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations.
- Classified patients into high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rate (<10 mL/kg/min) groups during ultrafiltration.
Main Results:
- Modified ultrafiltration increased blood pressure and hematocrit but decreased cerebral blood flow velocity and mixed venous oxygen saturation.
- Higher ultrafiltration flow rates correlated with greater reductions in cerebral blood flow velocity and oxygen saturation.
- Infants exposed to high flow rates exhibited more significant decreases in cerebral blood flow velocity and regional mixed venous saturation compared to moderate and low flow groups.
Conclusions:
- High blood flow rates during modified ultrafiltration transiently impair cerebral circulation in young infants.
- This effect may be due to increased diastolic runoff, causing a "stealing" effect from intracranial circulation.
- Findings are particularly relevant for infants with impaired cerebral autoregulation.
Background:
The intracranial hemodynamic effects of modified ultrafiltration in children are unknown. We investigated the effects of different blood flow rates during modified ultrafiltration on the cerebral hemodynamics of children with weights above and below 10 kg.
Methods:
Thirty-one children (weights: < or = 10 kg, n = 21; > 10 kg, n = 10) undergoing cardiopulmonary bypass were studied. Middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations were measured before, five minutes from the beginning, and at the end of ultrafiltration. Patients were classified according to their blood flow rates during ultrafiltration in three groups: high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rates (< 10 mL/kg/min).
Results:
During modified ultrafiltration, blood pressures and hematocrit increased (p < 0.001), but cerebral blood flow velocities and mixed venous oxygen saturations decreased (p < 0.001). A significant correlation was found between blood flow rates of ultrafiltration and the decline in mean cerebral blood flow velocity (r = - 0.48; p = 0.005) and cerebral oxygen saturation (r = - 0.49; p = 0.005) or hematocrit increase (r = 0.59; p = 0.001). Infants exposed to high flow rates had greater reduction of cerebral blood flow velocity and regional mixed venous saturation and higher hematocrit at the end of ultrafiltration compared with those subjected to moderate and low flow rates (p < 0.04). No significant difference was found between moderate and low flow groups. The flow rate of ultrafiltration was the only independent predictor of the changes in cerebral mixed venous oxygen saturation (p = 0.033).
Conclusions:
High blood flow rates through the ultrafilter during modified ultrafiltration transiently decrease the cerebral circulation in young infants compared with lower blood flow rates. These effects may be related to an increased diastolic runoff from the aorta into the ultrafiltration circuit that leads to a "stealing" effect from the intracranial circulation, which may be important in infants with dysfunctional cerebral autoregulation.
