Leukocyte filtration to decrease the number of adherent leukocytes in the cerebral microcirculation after a period of deep hypothermic circulatory arrest.
OBJECTIVE
Cardiopulmonary bypass and hypothermic circulatory arrest induce a systemic inflammatory response, including a cascade of leukocyte and endothelial cell activity, during the postischemic reperfusion phase. Accumulation of leukocytes in the brain can lead to neurologic problems after cardiac surgery. The beneficial effects of a leukocyte-depleting filter have been documented, but because of contradictory results the underlying function of the filter remains unclear.


METHODS
Twenty-two juvenile piglets (6 to 8 weeks) were randomly assigned to undergo cardiopulmonary bypass with or without a leukocyte-depleting filter 60 minutes before and 60 minutes after a 75-minute hypothermic circulatory arrest at 18 degrees C. The cerebral vessels were visualized with intravital microscopy through a cranial window placed over the parietal cortex. Rhodamine staining was used to observe adherent and rolling leukocytes in the cerebral postcapillary venules. The animals were electively killed 1 hour after weaning from cardiopulmonary bypass.


RESULTS
There were no significant differences between the study groups regarding hemodynamic data. Numbers of adherent activated leukocytes were lower in the leukocyte filtration group, reaching borderline statistical significance when assessed throughout the experiment (between-groups P = .069) and actual statistical significance when assessed during the rewarming period (between-groups P = .029).


CONCLUSIONS
The leukocyte-depleting filter succeeded in reducing the number of adherent leukocytes during the reperfusion period in an experimental operation with deep hypothermic circulatory arrest. Such a filter thus could mitigate cerebral reperfusion injury after cardiac surgery.
Alaoja
Hanna
H
Clinical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland. halaoja@student.oulu.fi
Niemelä
Eija
E
Anttila
Vesa
V
Dahlbacka
Sebastian
S
Mäkelä
Jussi
J
Kiviluoma
Kai
K
Laurila
Päivi
P
Kaakinen
Timo
T
Juvonen
Tatu
T
D000818:Animals; D001921:Brain / Q000098:blood supply*; D002315:Cardiopulmonary Bypass; D002448:Cell Adhesion; D002560:Cerebrovascular Circulation; D050792:Circulatory Arrest, Deep Hypothermia Induced; D047589:Leukocyte Reduction Procedures; D007962:Leukocytes / Q000502:physiology*; D008833:Microcirculation; D013552:Swine