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Cerebrovascular carbon dioxide reactivity in children anaesthetized with propofol
Cengiz Karsli1, Igor Luginbuehl, Marc Farrar
1Department of Anaesthesia, University of Toronto, Toronto, Ontario, Canada.
Insights
Propofol anesthesia in children maintains cerebrovascular CO2 reactivity, with cerebral blood flow velocity increasing alongside end-tidal CO2 levels. This indicates stable brain blood flow regulation during anesthesia in pediatric patients.
Area of Science:
- Pediatric Anesthesiology
- Neuroanesthesia
- Cerebrovascular Physiology
Background:
- Propofol is increasingly used for pediatric anesthesia due to its favorable pharmacokinetics.
- Its effects on cerebrovascular CO2 reactivity in children require further investigation.
- Understanding this is crucial for safe neurosurgical procedures in pediatric patients.
Purpose of the Study:
- To evaluate the impact of propofol anesthesia on carbon dioxide cerebrovascular reactivity in children.
- To assess how changes in end-tidal CO2 affect middle cerebral artery blood flow velocity during propofol infusion in pediatric patients.
Main Methods:
- Ten healthy children (1-6 years) undergoing elective urological surgery received propofol anesthesia and caudal epidural block.
- End-tidal CO2 (PECO2) was manipulated between 3.3, 5.2, and 7.2 kPa (25-55 mmHg) using an exogenous CO2 source.
- Middle cerebral artery blood flow velocity was measured using transcranial Doppler sonography.
Main Results:
- Cerebral blood flow velocity significantly increased as PECO2 rose from 3.3 to 5.2 kPa and from 5.2 to 7.2 kPa (P < 0.001 for both).
- No significant changes were observed in mean heart rate or blood pressure.
- This demonstrates preserved cerebrovascular CO2 responsiveness.
Conclusions:
- Cerebrovascular CO2 reactivity is maintained in healthy children anesthetized with propofol across a range of PECO2 values (3.3-7.2 kPa).
- Propofol anesthesia does not appear to impair the brain's ability to regulate blood flow in response to CO2 changes in this age group.
Background:
Propofol, by virtue of its favourable pharmacokinetic profile, is suitable for maintenance of anaesthesia by continuous infusion during neurosurgical procedures in adults. It is gaining popularity for use in paediatric patients. To determine the effects of propofol on carbon dioxide cerebrovascular reactivity in children, middle cerebral artery blood flow velocity was measured at different levels of endtidal (PECO2) by transcranial Doppler sonography.
Methods:
Ten ASA I or II children, aged 1-6 years undergoing elective urological surgery were enrolled. Anaesthesia comprized propofol aimed at producing an estimated steady-state serum concentration of 3 microg x ml-1 and a caudal epidural block. PECO2 was adjusted randomly in an increasing or decreasing fashion between 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) with an exogenous source of CO2 while maintaining ventilation parameters constant.
Results:
Cerebral blood flow velocity increased as PECO2 increased from 3.3 to 5.2 kPa (25-40 mmHg) (P < 0.001) and from 5.2 to 7.2 kPa (40-55 mmHg) (P < 0.001). Mean heart rate and blood pressure did not change significantly.
Conclusions:
This study demonstrates that cerebrovascular CO2 reactivity is maintained over PECO2 values of 3.3, 5.2 and 7.2 kPa (25, 40 and 55 mmHg) in healthy children anaesthetized with propofol.