Hypothermia after cardiac arrest does not alter serum inflammatory markers.
OBJECTIVE
Hypothermia improves survival and neurologic recovery after cardiac arrest. Cardiac arrest also triggers release of cytokines and inflammatory molecules, and it is unknown whether therapeutic hypothermia alters this inflammatory response. This study tested whether therapeutic hypothermia altered levels of inflammatory markers in serum.


METHODS
Prospective, randomized study.


METHODS
University research laboratory.


METHODS
Adult, male, Sprague-Dawley rats.


METHODS
Halothane-anesthetized rats were subjected to 8 mins of asphyxial cardiac arrest and resuscitation. Rat temperature was controlled at 37 degrees C throughout the experiment (normothermia) or reduced to 33 degrees C between 1 and 24 hrs after cardiac arrest (hypothermia). Serum cytokines were measured at baseline, 0.5, 1, 3, 6, 12, and 24 hrs after resuscitation using multiplex analyzer or enzyme-linked immunosorbent assay.


RESULTS
Hypothermic rats showed improved neurologic recovery at 12 and 24 hrs. Serum levels of tumor necrosis factor-alpha; macrophage inflammatory protein-1alpha; growth-related oncogene/keratinocyte chemokine; interleukin-2, -9, and -10; monocyte chemotactic protein-1; leptin; and intracellular adhesion molecule-1 increased over time, and the levels of interleukin-18 declined over time. No temporal trends in other molecules were detected. Levels of these molecules did not differ between temperature groups during the hypothermia phase (1-24 hrs).


CONCLUSIONS
These data suggest that altering the inflammatory response after cardiac arrest is not necessary for the beneficial effects of hypothermia. These data do not support a specific role of circulating cytokines in the neurologic injury after cardiac arrest.
Callaway
Clifton W
CW
Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA, USA. callawaycw@upmc.edu
Rittenberger
Jon C
JC
Logue
Eric S
ES
McMichael
Melissa J
MJ
D000818:Animals; D015415:Biomarkers / Q000097:blood; D016207:Cytokines / Q000378:metabolism; D006323:Heart Arrest / Q000378:metabolism* / Q000503:physiopathology; D007036:Hypothermia, Induced / Q000009:adverse effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D015415:Biomarkers; D016207:Cytokines