Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion.
BACKGROUND
Perfusion strategies during aortic surgery usually comprise hypothermic circulatory arrest (HCA), often combined with selective antegrade cerebral perfusion (SACP) or retrograde cerebral perfusion. Cerebral blood flow (CBF) is a fundamental parameter for which the optimal level has not been clearly defined. We sought to determine the CBF at a pump flow level of 6 mL/kg/min, previously shown likely to provide adequate SACP at 20°C in pigs.


METHODS
Repeated positron emission tomography (PET) scans were used to quantify the CBF and glucose metabolism throughout HCA and SACP including cooling and rewarming. Eight pigs on cardiopulmonary bypass were assigned to either HCA alone (n = 4) or HCA+SACP (n = 4). The CBF was measured by repeated [15O]water PET scans from baseline to rewarming. The cerebral glucose metabolism was examined by [18F]fluorodeoxyglucose PET scans after rewarming to 37°C.


RESULTS
Cooling to 20°C decreased the cortical CBF from 0.31 ± 0.06 at baseline to 0.10 ± 0.02 mL/cm3/min (p = 0.008). The CBF was maintained stable by SACP of 6 mL/kg/min during 45 minutes. After rewarming to 37°C, the mean CBF increased to 0.24 ± 0.07 mL/cm3/min, without significant differences between the groups at any time-point exclusive of the HCA period. The net cortical uptake (Ki) of [18F]fluorodeoxyglucose after rewarming showed no significant difference between the groups.


CONCLUSIONS
Cooling autoregulated the CBF to 0.10 mL/cm3/min, and 45 minutes of SACP at 6 mL/kg/min maintained the CBF in the present model. Cerebral glucose metabolism after rewarming was similar in the study groups.
Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden. Electronic address: thomas.tovedal@surgsci.uu.se.
Thomas
T
Tovedal
Department of Surgical Sciences, Nuclear Medicine & PET, Uppsala University, Uppsala, Sweden.
Mark
M
Lubberink
Department of Surgical Sciences, Nuclear Medicine & PET, Uppsala University, Uppsala, Sweden.
Arvid
A
Morell
Department of Medicinal Chemistry, Preclinical PET Platform, Uppsala University, Uppsala, Sweden.
Sergio
S
Estrada
Department of Surgical Sciences, Nuclear Medicine & PET, Uppsala University, Uppsala, Sweden.
Sandeep S V
SS
Golla
Department of Surgical Sciences, Thoracic Surgery, Uppsala University, Uppsala, Sweden.
Gunnar
G
Myrdal
Department of Surgical Sciences, Thoracic Surgery, Uppsala University, Uppsala, Sweden.
Rickard P F
RP
Lindblom
Department of Surgical Sciences, Thoracic Surgery, Uppsala University, Uppsala, Sweden.
Stefan
S
Thelin
Department of Surgical Sciences, Nuclear Medicine & PET, Uppsala University, Uppsala, Sweden.
Jens
J
Sörensen
Department of Medicinal Chemistry, Preclinical PET Platform, Uppsala University, Uppsala, Sweden.
Gunnar
G
Antoni
Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden.
Fredrik
F
Lennmyr
D000818:Animals; D001013:Aorta, Thoracic / Q000601:surgery; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000379:methods*; D004195:Disease Models, Animal; D005947:Glucose / Q000378:metabolism; D010477:Perfusion / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011183:Postoperative Complications / Q000175:diagnosis / Q000517:prevention & control*; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D013552:Swine; D014656:Vascular Surgical Procedures / Q000009:adverse effects
D005947:Glucose