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Propofol decreases cerebral blood flow velocity in anesthetized children
Cengiz Karsli1, Igor Luginbuehl, Mark Farrar
1Department of Anesthesia, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Insights
Higher propofol infusion rates in children significantly decrease cerebral blood flow velocity and mean arterial pressure. These findings suggest propofol has cerebral vasoconstrictive properties in pediatric patients.
Area of Science:
- Anesthesiology
- Pediatric Neurology
- Pharmacology
Background:
- Propofol is commonly used for anesthesia maintenance in adults due to its favorable pharmacokinetics.
- Its use in pediatric patients is increasing, necessitating an understanding of its effects on cerebral hemodynamics.
- Cerebral blood flow (CBF) regulation is critical in children, especially during neurosurgical procedures.
Purpose of the Study:
- To investigate the impact of different propofol administration levels on cerebral blood flow velocity (Vmca) in pediatric patients.
- To assess the relationship between propofol serum concentration and cerebral hemodynamic parameters in children undergoing surgery.
Main Methods:
- A randomized study involving 12 pediatric patients (1-6 years) undergoing elective urological surgery.
- Two propofol dosing regimens were employed: escalating and de-escalating concentrations.
- Transcranial Doppler (TCD) sonography was used to measure middle cerebral artery blood flow velocity (Vmca), alongside mean arterial pressure (MAP) and heart rate (HR).
Main Results:
- Higher estimated serum propofol concentrations led to significant reductions in Vmca (17%, P < 0.001).
- Mean arterial pressure (MAP) decreased by 6% (P < 0.002) and heart rate (HR) by 8% (P < 0.05) at higher propofol levels.
- These changes were statistically significant when compared to lower propofol concentrations.
Conclusions:
- Increased propofol infusion rates are associated with decreased cerebral blood flow velocity and mean arterial pressure in children.
- Propofol may exert cerebral vasoconstrictive effects in the pediatric population.
- These findings have implications for anesthetic management in children, particularly those at risk for altered cerebral perfusion.
Purpose:
Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in pediatric patients. To determine the effects of propofol on cerebral blood flow in children, middle cerebral artery blood flow velocity (Vmca) was measured at different levels of propofol administration by transcranial Doppler (TCD) sonography.
Methods:
Twelve ASA I or II children, aged one to six years undergoing elective urological surgery were randomized to receive one of two propofol dosing regimens. Half of the patients received propofol in an escalating fashion, initially targeting an estimated steady-state serum concentration of 3 microg x mL-1, which was then doubled. The other half received propofol designed initially to target the high concentration followed by the lower one. In each child anesthesia was induced and maintained with propofol according to the protocol, rocuronium was given to facilitate tracheal intubation, and a caudal epidural block was performed. A TCD probe was placed appropriately to measure Vmca. Cerebral blood flow velocity (CBFV), mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously at both levels of propofol administration.
Results:
Twelve patients were studied. At the higher estimated target serum propofol concentration there were significant decreases in Vmca (17%, P < 0.001), MAP (6%, P < 0.002) and HR (8%, P < 0.05) when compared to the lower targeted concentration.
Conclusion:
This study shows that a higher rate of propofol infusion is associated with lower CBFV and MAP values in children. Propofol's cerebral vasoconstrictive properties may be responsible for this finding.