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Cerebral haemodynamics during proximal aortic cross-clamping
P Aadahl1, O D Saether, R Stenseth
1Department of Anaesthesiology, Trondheim University Clinic, Norway.
European Journal of Vascular Surgery
|February 1, 1991
Summary
Thoracic aortic cross-clamping significantly increases cerebral blood flow and intracranial pressure in pigs. These effects, including enhanced internal carotid artery flow, reverse upon clamp release, suggesting protective mechanisms for the brain.
Area of Science:
- Cardiovascular Physiology
- Cerebrovascular Regulation
- Surgical Hemodynamics
Background:
- Understanding cerebral blood flow (CBF) dynamics during aortic procedures is crucial for preventing neurological complications.
- Thoracic aortic cross-clamping (XC) can alter systemic and cerebral hemodynamics.
- The impact of aortic XC on cerebral microcirculation and intracranial pressure (ICP) requires detailed investigation.
Purpose of the Study:
- To investigate the effects of thoracic aortic cross-clamping (XC) on cerebral blood flow, microcirculation, and intracranial pressure (ICP) in a porcine model.
- To analyze hemodynamic changes in the internal carotid artery (ICA) and middle cerebral artery (MCA) during aortic XC.
- To evaluate the immediate post-XC recovery of cerebral parameters.
Main Methods:
- Utilized electromagnetic flowmetry for ICA blood flow measurement.
- Employed laser Doppler technique to assess cerebral microcirculation.
- Measured ICP using a fiber optic pressure monitoring catheter.
- Recorded MCA blood flow velocity with transcranial Doppler.
- Determined cardiac output via thermodilution.
- Performed aortic XC distal to the left subclavian artery for 30 minutes in pigs.
Main Results:
- Aortic XC led to a significant 191% increase in ICA blood flow (p<0.05).
- Mean and maximal MCA blood flow velocity increased by 125% (p<0.01).
- ICP rose by 163% (p<0.05), and cerebral flux increased by 23% (p<0.05).
- All measured parameters returned to baseline levels within minutes after XC release.
Conclusions:
- Thoracic aortic XC induces a substantial increase in cerebral blood flow and ICP in pigs, correlated with increased cardiac output.
- These findings support the hypothesis that enhanced blood flow to the anterior spinal artery may mitigate neurological damage after proximal aortic XC.
- The observed hemodynamic responses highlight the brain's compensatory mechanisms during aortic manipulation.