Effects of Hypothermia on Blood Endogenous Endotoxin Levels During Cardiopulmonary Bypass

Abstract

Endotoxin activates white blood cells and complement and produces a spectrum of clinical syndromes ranging from fever to septic shock. Although production of endogenous endotoxemia during cardiopulmonary bypass (CPB) has recently been reported, the role of hypothermia on endotoxemia is not clear. In this study, we evaluated the effects of moderate (24-28 degrees C) and mild (32-34 degrees C) hypothermia on blood endotoxin levels. The study population consisted of 20 patients who underwent coronary artery bypass grafting (CABG) with CPB. Moderate systemic hypothermia was applied during aortic cross-clamping in ten patients (group 1) and mild hypothermia in the remaining ten patients (group 2). The mean rectal temperatures were 26.8 +/- 1.2 degrees C in group 1 and 33.8 +/- 0.8 degrees C in group 2. The blood samples for endotoxin level measurements were obtained before CPB, during aortic cross-clamping, immediately after the release of the cross-clamp, 20 minutes after the release of the cross-clamp, after CPB, and 2 hours postoperatively. There were no endotoxins in any of the samples before CPB, but it was detected after CPB in both groups. The endotoxin levels were significantly higher in group 1 than in group 2. The present study suggests that when hypothermia is the technique of choice, the deleterious effects of endotoxemia on patients with comorbidity must be considered.

Intracellular monocyte and serum cytokine expression is modulated by exhausting exercise and cold exposure

“…The mechanism underlying the abovementioned differences in cytokine generation is not clear, but it can be argued that cold-associated modulation of cytokine production may be related to induction of systemic endotoxemia, provoked by alterations in central hemodynamics and stress hormone release associated with enhanced thermoregulatory demands. In support of this notion is the observation that moderate cold exposure leads to a sharp reduction in splanchnic blood flow and ischemia (24) that promotes translocation of LPS into the systemic circulation (26). Also, on rewarming, the potential for even greater endotoxemia exists due to transient splanchnic reperfusion (24).…”

Anti-Inflammatory Effects of Alkaline Phosphatase in Coronary Artery Bypass Surgery with Cardiopulmonary Bypass

“…Since normothermia was applied in all our patients, this may be another explanation for the low inflammatory response. It is described that hypothermia leads to significantly higher levels of endotoxin with increasing levels of endotoxin during and after deep hypothermia [23].…”

Minimizing Systemic Inflammation During Cardiopulmonary Bypass in the Pediatric Population

“…In a randomized study comparing two groups of pediatric patients perfused with mild (34°C) or moderate (24°C) hypothermia, there was no evidence of any temperature influence on systemic inflammatory response and organ injury . Higher release of endotoxin was described during deep hypothermia when compared with mild hypothermia .…”