Endotoxemia related to cardiopulmonary bypass is associated with increased risk of infection after cardiac surgery: a prospective observational study.

INTRODUCTION: Previous studies have documented a high frequency of endotoxemia associated with cardiopulmonary bypass (CPB). Endotoxemia may be responsible for some of the complications associated with cardiac surgery. The purpose of the study was to examine the prevalence of endotoxemia during cardiopulmonary bypass supported aortocoronary bypass grafting surgery (ACB) using a new assay, the Endotoxin Activity Assay (EAA), and explore the association between endotoxemia and post-operative infection. METHODS: The study was a single center prospective observational study measuring EAA during the perioperative period for elective ACB. Blood samples were drawn at induction of anesthesia (T1), immediately prior to release of the aortic cross-clamp (T2), and on the first post-operative morning (T3). The primary outcome was the prevalence of endotoxemia. Secondary outcomes assessed included infection rates, intensive care unit (ICU) and hospital length of stay. An EAA of < 0.40 units was interpreted as "low", 0.41 to 0.59 units as "intermediate", and ≥ 0.60 units as "high". RESULTS: A total of 57 patients were enrolled and 54 patients were analyzable. The mean EAA at T1 was 0.38 +/- 0.14, at T2 0.39 +/- 0.18, and at T3 0.33 +/- 0.18. At T2 only 13.5% (7/52) of patients had an EAA in the high range. There was a positive correlation between EAA and duration of surgery (P = 0.02). In patients with EAA ≥ 0.40 at T2, 26.1% (6/23) of patients developed post-operative infections compared to 3.5% (1/29) of those that had a normal EAA (P = 0.0354). Maximum EAA over the first 24 hours was also strongly correlated with risk of post-operative infection (P = 0.0276). CONCLUSIONS: High levels of endotoxin occur less frequently during ACB than previously documented. However, endotoxemia is associated with a significantly increased risk of the development of post-operative infection. Measuring endotoxin levels during ACB may provide a mechanism to identify and target a high risk patient population.

Cerebral cortical gene expression in acutely anemic rats: a microarray analysis.

PURPOSE: Hemodilution in perioperative patients has been associated with neurological morbidity and increased mortality by undefined mechanisms. This study assesses whether hemodilutional anemia up-regulated inflammatory cerebral gene expression (microarray) to help define the mechanism. METHODS: Hemodilution was performed in anesthetized rats by exchanging 50% of the estimated blood volume (30 mL kg(-1)) with pentastarch. Two groups of control animals were utilized, i.e., a non-anesthetized control (Normal Control) and an anesthetized control group (Anesthesia Control). Blood pressure, hemoglobin concentration, and arterial blood gas analysis were performed before and after hemodilution. Cerebral cortex was harvested from isoflurane-anesthetized rats (n = 6) after 6 and 24 hr of recovery and was used to perform complimentary DNA (cDNA) microarray analyses. Pro-inflammatory chemokine and cytokine protein levels were also measured. RESULTS: Microarray analysis demonstrated up-regulation of 72 and 27 genes (6 and 24 hr, respectively) in anemic cerebral cortex. These genes were involved in a number of biological functions, including (1) inflammatory responses; (2) angiogenesis; (3) vascular homeostasis; (4) cellular biology; and (5) apoptosis. Chemokine ribonucleic acid (RNA) expression (CXCL-1, -10, and -11) was highest in anemic brain tissue (P < 0.0125 for each). Protein measurements demonstrated a significant increase in interleukin-6, tumor necrosis factor alpha, and monocyte chemoattractant protein-1 (P < 0.05 for each). CONCLUSION: This study utilizes microarray technology to elucidate changes in cerebral cortical gene expression in response to acute hemodilution. These findings demonstrate an increase in pro-inflammatory chemokines (RNA, protein) and cytokines (protein). An improved understanding of the inflammatory response to anemia may help to minimize associated morbidity and mortality.

Triple nutrient supplementation improves survival, infarct size and cardiac function following myocardial infarction in rats.

BACKGROUND AND AIM: We evaluated the impact of triple nutrient supplementation (TNS: carnitine, taurine and coenzyme Q(10)) vs. carnitine alone (CARN) or placebo on survival, infarct size, cardiac function and metabolic gene expression using a model of myocardial infarction (MI) in rats. METHODS AND RESULTS: Male Wistar rats were randomized to three groups divided in two independent studies prior to ligation of the left anterior descending coronary artery (LAD): TNS vs. Placebo and TNS vs. CARN. Nutrient supplementation [L-carnitine (300 mg/day), coenzyme Q(10) (15 mg/kg body weight/day) and taurine (0.1M)] was administered daily for four weeks prior to and for 10 days after MI. At that time, cardiac function and infarct size were measured. Metabolic gene (mRNA) expression in the peri-infarct tissue of left ventricle from TNS, placebo or corresponding time-control rats (TNS or placebo without LAD ligation) was measured 10 days after MI. When compared to placebo, TNS significantly improved survival (60% vs. 34%, p<0.02), cardiac function, and reduced infarct size (30+/-7% vs. 42+/-9%, p<0.001). Although CARN improved survival like TNS (45% vs. 50%, not significant), it did not reduce infarct size (32+/-14% vs. 19+/-10%, p<0.05) or delay myocardial remodeling. In the placebo group, MI was associated with a significantly altered pattern of metabolic gene expression (glucose transporter 1, liver carnitine palmitoyl transferase 1, medium-chain acyl-CoA dehydrogenase; p<0.01 for all three) in the left ventricle peri-infarct tissue. In contrast, gene expression was normalized in the group receiving TNS. CONCLUSIONS: Our results support the potential cardioprotective impact of TNS during myocardial ischemia. In contrast to carnitine supplementation alone, TNS improved survival as well as cardiac function, gene expression and delayed remodeling.

Effect of malnutrition and short-term refeeding on peripheral blood mononuclear cell mitochondrial complex I activity in humans.

BACKGROUND: Previous investigations in rats have shown that the first enzyme of the mitochondrial electron transport chain (complex I) is altered in peripheral blood mononuclear cells (PBMCs) and muscle by dietary manipulations. OBJECTIVE: We hypothesized that similar changes would occur in human PBMCs as a result of dietary malnutrition and short-term refeeding irrespective of the presence or absence of active inflammatory bowel disease (IBD). DESIGN: Fourteen malnourished patients with active IBD, 13 malnourished patients without IBD, and 42 healthy subjects were investigated. Complex I activity, body mass index, body composition, energy and protein intakes, and resting energy expenditure were measured. Five patients without IBD and 6 patients with IBD were investigated after 7 d of refeeding. RESULTS: In patients without IBD, weight loss was mainly due to a loss of fat mass. In contrast, weight loss in IBD patients was due to a loss of both fat-free mass and fat mass. Complex I activity was reduced to the same degree in both groups of patients and was significantly lower than that observed in healthy subjects. In both groups of patients, complex I activity correlated significantly with body weight, body mass index, percentage weight loss, and fat mass. Complex I activity increased significantly after 1 wk of refeeding in both groups of patients before observed changes of measured nutritional assessment indexes. CONCLUSION: Our study showed that mitochondrial complex I activity measured in PBMCs seems to be a specific marker of dietary malnutrition and responds rapidly to refeeding.

Effect of feeding malnourished patients for 1 mo on mitochondrial complex I activity and nutritional assessment measurements.

BACKGROUND: We showed previously that the activity of complex I (the first enzyme of the electron transport chain) in peripheral blood mononuclear cells decreases with malnutrition and increases to a subnormal value after 1 wk of refeeding, but the traditional markers of nutritional status do not do so. OBJECTIVE: The aim of this study was to ascertain whether a period of nutritional intervention longer than 1 wk would normalize complex I activity and traditional markers of nutritional status. DESIGN: Fifteen malnourished patients (7 women and 8 men) with > or =10% body weight loss over the previous 6 mo were studied on the day of their admission to hospital and 7, 14 and 30 d after the beginning of nutritional support. Complex I activity in peripheral blood mononuclear cells, weight, height, body composition, body water compartments, dietary intake, and serum albumin concentrations were measured on each occasion. The results before and during nutritional intervention were compared with values obtained in 30 healthy volunteers (17 women and 13 men). RESULTS: Complex I activity increased significantly after the first week of refeeding (P < 0.001) and reached a normal value after 1 mo of nutritional supplementation. Among the classic markers of nutritional status, only the ratio of extracellular water to intracellular water tended to decrease over the refeeding period. CONCLUSION: Complex I activity increases rapidly and is normalized by refeeding at a time when other markers of nutritional status do not change significantly.

A low pretransplant peripheral blood mononuclear cell complex I activity predicts metabolic disturbances and inability to regain fat free mass in cirrhotic patients undergoing liver transplantation.

Liver cirrhosis is associated with malnutrition and often, after liver transplantation, with the development of obesity and the inability to gain lean body mass. We have previously shown that peripheral blood mononuclear cell (PBMNC) complex I activity could be an appropriate marker for nutritional assessment. In this context, we hypothesized that a low pretransplant PBMNC complex I activity may predict a poor nutritional status in cirrhotic patients undergoing liver transplantation. Fifteen cirrhotic patients (CP) (8 men and 7 women) were recruited and investigated before and 4 months after liver transplantation. Body weight, body composition by DEXA, anthropometric measures (triceps skinfold thickness and midarm muscle circumference), resting energy expenditure, respiratory quotient and PBMNC complex I activity were measured on both time points. Patients were divided into 2 groups depending on their pretransplant PBMNC complex I activity (low vs high complex I activity [CP(low CI) vs CP(high CI)]), using as an arbitrary cutoff value-the mean complex I activity observed in age-matched healthy controls. Before transplantation, the CP(low CI) group who showed a lower complex I activity (2.11 +/- 0.53 vs 4.54 +/- 0.98 nmol/min per milligram of protein, P < .01) was significantly younger (44 +/- 9 vs 62 +/- 8 years old, P < .01); no differences were observed for any other nutritional parameters when compared to the CP(high CI) group. After transplantation, only the CP(low CI) group demonstrated a significant increase of complex I activity (+77%, P < .01), respiratory quotient (+10.5%, P < .02), triceps skinfold thickness (+126%, P < .005), and a significant decrease of fat-free mass (-8%, P < .01). In summary, our findings indicate that a low pretransplant PBMNC complex I activity in cirrhotic patients could be a useful marker of poor nutritional status despite the lack of traditional indicators of malnutrition by predicting metabolic disturbances and an inability to regain fat-free mass after liver transplantation.

Increased cerebral and renal endothelial nitric oxide synthase gene expression after cardiopulmonary bypass in the rat.

OBJECTIVE: Hemodilution and endothelial nitric oxide synthase genetic polymorphism may contribute to cerebral and renal injury after cardiopulmonary bypass. This study tested the hypothesis that cardiopulmonary bypass and anemia stimulate an increase in cerebral and renal endothelial nitric oxide synthase gene expression in an experimental model of cardiopulmonary bypass. METHODS: Anesthetized rats underwent a sham procedure without cardiopulmonary bypass (sham, n = 5), normothermic bypass for 1 hour (CPB, n = 7), or bypass plus hemodilutional anemia (CPB anemia, n = 9). After 24 hours of recovery, RNA was extracted from the cerebral cortex, renal cortex, and renal medulla. Quantitative reverse transcriptase polymerase chain reaction was used to assess endothelial nitric oxide synthase messenger RNA levels in brain and kidney tissues. RESULTS: The hemoglobin concentration of anemic CPB rats was significantly lower than that of nonanemic rats on bypass (64 +/- 5 vs 99 +/- 8 g x L(-1), P < .001). Cerebral cortical endothelial nitric oxide synthase messenger RNA levels were increased after cardiopulmonary bypass relative to those of the sham group (11.2 +/- 4.2 vs 6.3 +/- 1.5 fg, P = .031), without a further increase in anemic rats. Renal medullary endothelial nitric oxide synthase messenger RNA levels were significantly higher in the CPB anemia group than in the sham and CPB groups (7.1 +/- 4.4 fg vs 1.8 +/- 0.4 fg vs 3.0 +/- 0.6 fg, P < .001). Renal cortical endothelial nitric oxide synthase messenger RNA levels did not change significantly. CONCLUSIONS: Normothermic cardiopulmonary bypass was associated with higher endothelial nitric oxide synthase messenger RNA levels in kidney and brain than was the sham procedure 24 hours after cardiopulmonary bypass. Anemia accentuated the increase in renal medullary, but not cerebral cortical, endothelial nitric oxide synthase expression. These data provide an approach for exploring potential mechanisms by which endothelial nitric oxide synthase may contribute to renal and cerebral dysfunction after cardiopulmonary bypass and anemia.