 Blood flow to the gut is decreased markedly and intestinal tissue becomes ischemic during CA and CPR, particularly when vasoconstrictor drugs such as epinephrine, are given. IRI of the intestine increases intestinal permeability leading to intestinal microbial translocation and endotoxin release that can stimulate and perpetuate systemic inflammation and cause subsequent multi-organ dysfunction. Endotoxin also increases body temperature and energy expenditure and may attenuate TH induced reductions in BMR and hence, decrease efficacy. The purpose of this novel pilot study is to detect systemic endotoxin release following CA in humans and determine association with cytokine activation, and BMR alterations during TH. 