Cerebral metabolism during deep hypothermic circulatory arrest vs moderate hypothermic selective cerebral perfusion in a piglet model: a microdialysis study.
BACKGROUND
Few data exist regarding antegrade selective cerebral perfusion (ASCP) and its application in newborn and juvenile patients. Clinical data suggest ASCP alone to be superior to deep hypothermic circulatory arrest (DHCA); however, the effects of moderate hypothermia during ASCP on cerebral metabolism in this patient population are still unclear.


METHODS
After obtaining the approval from animal investigation committee, 16 piglets were randomly assigned to circulatory arrest combined with either ASCP at 27 degrees C or DHCA at 18 degrees C for 90 min. Cerebral oxygen extraction fraction (COEF) from blood as well as cerebral tissue glucose, glycerol, lactate, pyruvate, and the lactate/pyruvate ratio (L/P ratio) by microdialysis were obtained repeatedly.


RESULTS
COEF was lower during cooling and rewarming, respectively, in the DHCA18 group compared to the ASCP27 group (30 +/- 8 vs 56 +/- 13% and 35 +/- 6 vs 58 +/- 7%, respectively). Glucose decreased in both the DHCA18 and ASCP27 groups during the course of cardiopulmonary bypass (CPB), but were higher in the ASCP27 group during ASCP, compared to the DHCA18 group during circulatory arrest (0.7 +/- 0.1 vs 0.2 +/- 0.1 mm.l(-1), P < 0.05). Pyruvate was higher (ASCP27 vs DHCA18: 53 +/- 17 vs 6 +/- 2 microm.l(-1), P < 0.05), and the L/P ratio increased during circulatory arrest in the DHCA18 group, compared to the selective perfusion phase of the ASCP27 group (DHCA18 vs ASCP27: 1891 +/- 1020 vs 70 +/- 28, P < 0.01).


CONCLUSIONS
In this piglet model, both cerebral oxygenation and microdialysis findings suggested a depletion of cerebral energy stores during circulatory arrest in the DHCA18 group, compared to selective cerebral perfusion combined with circulatory arrest in the ASCP27 group.
Cavus
Erol
E
Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Campus Kiel, Schwanenweg 21, Kiel 24105, Germany. e.cavus@t-online.de
Hoffmann
Grischa
G
Bein
Berthold
B
Scheewe
Jens
J
Meybohm
Patrick
P
Renner
Jochen
J
Scholz
Jens
J
Boening
Andreas
A
D000818:Animals; D001921:Brain / Q000098:blood supply / Q000378:metabolism*; D002548:Cerebral Revascularization / Q000009:adverse effects*; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000009:adverse effects*; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis / Q000379:methods*; D023421:Models, Animal; D010100:Oxygen / Q000378:metabolism; D010313:Partial Pressure; D019289:Pyruvic Acid / Q000378:metabolism; D011897:Random Allocation; D013552:Swine; D016896:Treatment Outcome
D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose; D010100:Oxygen