Cerebral haemodynamics during proximal aortic cross-clamping.
This study was carried out to examine cerebral blood flow, including the microcirculation and intracranial pressure during cross-clamping (XC) of the thoracic aorta in pigs. Blood flow in the internal carotid artery was measured by electromagnetic flowmetry. Cerebral microcirculation was studied by the laser Doppler technique, and intracranial pressure measured by applying a fibre optic pressure monitoring catheter in the same craniotomy. Maximal and mean blood flow velocity of the middle cerebral artery was recorded using a transcranial Doppler and cardiac output measured by thermodilution. The thoracic aorta was cross-clamped distal to the left subclavian artery for 30 min. During aortic XC the internal carotid artery blood flow increased 191% (p less than 0.05). Simultaneously mean and maximal blood flow velocity of the middle cerebral artery both increased 125% (p less than 0.01). Intracranial pressure increased 163% (p less than 0.05), and there was an increase in cerebral flux of 23% (p less than 0.05). Within the first minutes following the release of XC, all values decreased to preocclusive values. In conclusion, we observed a significant increase in cerebral blood flow during XC of the thoracic aorta. This is in accordance with the finding of a simultaneous increase in cardiac output. These haemodynamic changes support the theory that an increased blood flow via the proximal feeding system to the anterior spinal artery might be important in avoiding neurological sequelae following proximal aortic XC.
Aadahl
P
P
Department of Anaesthesiology, Trondheim University Clinic, Norway.
Saether
O D
OD
Stenseth
R
R
Juul
R
R
Myhre
H O
HO
D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D002343:Carotid Artery, Internal / Q000502:physiology; D002536:Cerebral Arteries / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003250:Constriction; D007427:Intracranial Pressure / Q000502:physiology; D007834:Lasers; D008833:Microcirculation / Q000502:physiology; D013552:Swine