Amelioration of intestinal reperfusion injury by moderate hypothermia is associated with serum sICAM-1 levels

Effects of intraoperative temperatures on postoperative infections in infants and neonates

BACKGROUND

Perioperative hypothermia has been shown to increase surgical site infection (SSI) rates in adults. We sought to characterize whether intraoperative hypothermia or hyperthermia is associated with postoperative infections in infants.

METHODS

We conducted a retrospective review of patients ≤6 months old who underwent surgical procedures from November 2013 to October 2015 at a Level I ACS Children's Surgical Center. The outcome was infections within 30 days after operation, with particular attention to SSI. Data obtained included weight and age at surgery, American Society of Anesthesiologists (ASA) physiologic status, wound class, case length, blood transfusion within 72 h of surgery, and administration of prophylactic antibiotics. Temperatures were classified as hypothermia (T < 36 °C), normothermia (T = 36.0 to 37.9 °C), and hyperthermia (T ≥ 38 °C).

RESULTS

The 885 patients had 25 SSIs (2.8%) and 11 nonsurgical site infections (1.2%). On univariate analysis, weight at surgery, higher ASA, perioperative transfusions, and longer case length were associated with higher rate of SSI. Higher median T_high, higher median T _low, and any hyperthermia were associated with higher rate of SSI. On multivariable logistic regression adjusted analyses, hyperthermia at any time during the case was associated with SSI (OR 3.47, [95% CI 1.34, 9.04], p = 0.011). Transfusions were also associated with higher SSI rates (OR 3.60 [95% CI, 1.28, 10.3], p = 0.016).

CONCLUSIONS

Intraoperative hyperthermia is associated with increased SSI rates in infants.

LEVEL OF EVIDENCE

III.

Moderate Hypothermia Provides Better Protection of the Intestinal Barrier than Deep Hypothermia during Circulatory Arrest in a Piglet Model: A Microdialysis Study

INTRODUCTION

This study aimed to assess the effects of different temperature settings of hypothermic circulatory arrest (HCA) on intestinal barrier function in a piglet model.

METHODS

Twenty Wuzhishan piglets were randomly assigned to 40 min of HCA at 18°C (DHCA group, n = 5), 40 min of HCA at 24°C (MHCA group, n = 5), normothermic cardiopulmonary bypass (CPB group, n = 5) or sham operation (SO group, n = 5). Serum D-lactate (SDL) and lipopolysaccharide (LPS) levels were determined. Microdialysis parameters (glucose, lactate, pyruvate and glycerol) in the intestinal dialysate were measured. After 180 min of reperfusion, intestinal samples were harvested for real-time polymerase chain reaction and western blotting measurements for E-cadherin and Claudin-1.

RESULTS

Higher levels of SDL and LPS were detected in the DHCA group than in the MHCA group (P < 0.001). Both MHCA and DHCA groups exhibited lower glucose levels, higher lactate and glycerol levels and a higher lactate to pyruvate (L/P) ratio compared with the CPB group (p<0.05); the DHCA group had higher lactate and glycerol levels and a higher L/P ratio (p<0.05) but similar glucose levels compared to the MHCA group. No significant differences in E-cadherin mRNA or protein levels were noted. Upregulation of claudin-1 mRNA levels was detected in both the DHCA and MHCA animals' intestines (P < 0.01), but only the DHCA group exhibited a decrease in claudin-1 protein expression (P < 0.01).

CONCLUSION

HCA altered the energy metabolism and expression of epithelial junctions in the intestine. Moderate hypothermia (24°C) was less detrimental to the markers of normal functioning of the intestinal barrier than deep hypothermia (18°C).

The effect of therapeutic hypothermia after cardiopulmonary resuscitation on ICAM-1 and NSE levels in sudden cardiac arrest rabbits

PURPOSE

To assess the effects of hypothermia and normothermia treatments for sudden cardiac arrest (SCA) on brain injury recovery in rabbit models.

METHODS

Cardiopulmonary resuscitation (CPR) was implemented on apnea-induced SCA rabbit models. Fifty survived rabbits were then randomly received hypothermia (n = 25, 32-34°C) or normothermia treatment (n = 25, 39-39.5°C) for 12 hours. The expected body temperatures were achieved within the first two hours, maintained for ten hours and then rewarmed. The physiological parameters, neurologic function, and the levels of adhesion molecule ICAM-1 and neuron-specific enolase (NSE) were monitored.

RESULTS

Hypothermia-treated rabbits had lower heart rate when achieving hypothermia (p < 0.0001) and higher SjvO2 after hypothermia maintenance (p = 0.038). The hypothermia group achieved better brain recovery performance according to the neurological deficit grading scale. ICAM-1 and NSE levels in both serum and CSF of the hypothermia group were lower than the normothemia group (all p < 0.0001) during hypothermia maintenance.

CONCLUSION

Hypothermia treatment after CPR provides better outcome than normothermia treatment in SCA rabbits. Hypothermia can reduce the ICAM-1 and NSE levels in both serum and cerebrospinal fluid (CSF). This study supports the clinical implementation of hypothermia treatment for SCA and reveals that ICAM-1 and NSE are involved in the recovery of brain function after resuscitation.

Hypothermia: novel approaches for premature infants

Hypothermia for hypoxic ischemic encephalopathy has recently permeated clinical practice for term infants. Speculation regarding a neuroprotective benefit of hypothermia for premature infants with HIE has been raised as a need for further research. Hypothermia for other indications including necrotizing enterocolitis with the hope of tissue preservation following injury is less well studied. A summary of evidence for hypothermia and premature infants is presented in this brief report.

Human intestinal ischemia-reperfusion-induced inflammation characterized: experiences from a new translational model

Human intestinal ischemia-reperfusion (IR) is a frequent phenomenon carrying high morbidity and mortality. Although intestinal IR-induced inflammation has been studied extensively in animal models, human intestinal IR induced inflammatory responses remain to be characterized. Using a newly developed human intestinal IR model, we show that human small intestinal ischemia results in massive leakage of intracellular components from ischemically damaged cells, as indicated by increased arteriovenous concentration differences of intestinal fatty acid binding protein and soluble cytokeratin 18. IR-induced intestinal barrier integrity loss resulted in free exposure of the gut basal membrane (collagen IV staining) to intraluminal contents, which was accompanied by increased arteriovenous concentration differences of endotoxin. Western blot for complement activation product C3c and immunohistochemistry for activated C3 revealed complement activation after IR. In addition, intestinal IR resulted in enhanced tissue mRNA expression of IL-6, IL-8, and TNF-alpha, which was accompanied by IL-6 and IL-8 release into the circulation. Expression of intercellular adhesion molecule-1 was markedly increased during reperfusion, facilitating influx of neutrophils into IR-damaged villus tips. In conclusion, this study for the first time shows the sequelae of human intestinal IR-induced inflammation, which is characterized by complement activation, production and release of cytokines into the circulation, endothelial activation, and neutrophil influx into IR-damaged tissue.

Different patterns of intestinal response to injury after arterial, venous or arteriovenous occlusion in rats

AIM: To investigate the differences in injury patterns caused by arterial, venous or arteriovenous mesenteric occlusion.

METHODS: Male Wistar rats were separated equally into four groups. Occlusion was performed by clamping the superior mesenteric artery (A), the mesenteric vein (V) or both (AV) for 30 min, followed by 60 min of reperfusion. A control group received sham surgery only. Intestinal sections were examined for histological damage and serum tumor necrosis factor-α (TNF-α), endothelin-1 (ET-1), P-selectin, antithrombin III (ATIII) and soluble intracellular adhesion molecule-1 (ICAM-1) concentrations were measured.

RESULTS: All groups showed significant mucosal injury compared to controls. Furthermore, mucosal injury was significantly more severe in the V and AV groups compared to the A group (3.6 ± 0.55, 3.4 ± 0.55 and 2 ± 0.71, respectively, P = 0.01). ICAM-1 was similarly elevated in all groups, with no significant differences between the groups. P-selectin levels were significantly elevated in the V and AV groups but not the A group (1.4 ± 0.5 ng/mL, 2.52 ± 0.9 ng/mL and 0.02 ± 0.01 ng/mL, respectively, P = 0.01) and ET-1 was significantly elevated in the A and V groups but not the AV group (0.32 ± 0.04 pg/mL, 0.36 ± 0.05 pg/mL and 0.29 ± 0.03 pg/mL, respectively, P = 0.01) compared to sham controls. ATIII levels were markedly depleted in the V and AV groups, but not in the A group (29.1 ± 5.2 pg/mL, 31.4 ± 21.8 pg/mL and 55.8 ± 35.6 pg/mL, respectively, P = 0.01), compared to controls. Serum TNF-α was significantly increased in all groups compared to sham controls (1.32 ± 0.87 ng/mL, 1.79 ± 0.20 ng/mL and 4.4 ± 0.69 ng/mL, for groups A, V and AV, respectively, P = 0.01), with higher values in the AV group.

CONCLUSION: Different patterns of response to ischemia/reperfusion are associated with venous, arterial or arteriovenous occlusion. Venous and arteriovenous occlusion was associated with the most severe alterations.

Is there a self-preserving hypothermic mechanism in shock?

Hypoxia-induced hypothermia (HIH) is regarded as an adaptive response to hypoxia in a variety of creatures, but no details of the mechanism have yet been elucidated in the clinical setting. This study was designed to analyze alteration of core body temperature with hemorrhagic shock and to clarify HIH in the clinical setting. Patients were categorized in the hemorrhage shock (S, n = 15) or cardiopulmonary arrest (C, n = 88) group. The tympanic membrane temperature (TMT) was measured, and the length of the interval of call-to-arrival (CTA) at a hospital was set as the time-course parameter. There was a significant negative linear relationship between CTA interval and TMT (S group: TMT = -0.055 degrees C, CTA = +36.1 min, r = -0.833, P < 0.001; C group: TMT = -0.046 degrees C, CTA = +36.3 min, r = -0.548, P < 0.001). Analysis of variance revealed no significant difference in the slope of the regression lines of both groups. However, when the CTA interval was used as a covariate, there was a significant difference in the TMT (P = 0.014), which means that the regression line of the S group was significantly lower than that of the C group with time. Furthermore, in the S group, all patients were hypothermic (<35 degrees C) when their CTA interval was more than 20 min; on the other hand, in the C group, only 64 (75%) of 85 were hypothermic. Patients in S group were more likely to become hypothermic (P < 0.05). In humans with cellular hypoxia, HIH takes place, as seen in other animals. This result emphasizes the necessity for studies of analysis of the mechanisms of temperature control and determination of optimal body temperature during acute critical care.

The effect of L-arginine and aprotinin on intestinal ischemia-reperfusion injury

BACKGROUND

Intestinal ischemia/reperfusion (I/R) results in local mucosal injury, systemic injuries, and organ dysfunction. These injuries are characterized by altered microvascular and epithelial permeability and villous damage. Activation of neutrophils, platelets, and endothelial factors are known to be involved in this process. Cytokines such as TNF-alpha, IL-1, IL-6, and oxygen-derived free radicals are believed to be important pathogenic mediators. Capillary no-reflow is also known to play a role in I/R. The aim of our study was to examine the role of L-arginine, a known nitric oxide (NO) donor, and aprotinin, a protease inhibitor with multiple effects, on intestinal I/R.

METHODS

Pigs weighing 20-25 kg were used. Ischemia was established by clamping the superior mesenteric artery (SMA) at its origin and was sustained for 2 hours. Duration of reperfusion was 2 hours. The animals were divided into four groups: group A, the control group, which was submitted to I/R injury only; group B, in which L-arginine was administered at a rate of 5 mg/kg/min during ischemia and continuing throughout reperfusion; group C, in which aprotinin was administered with an initial bolus dose of 20,000 U/kg during ischemia followed by a continuous dose at 50 U/hour throughout reperfusion; and group D in which both substances were administered. In all groups TNF-alpha, IL-1, and IL-6 levels were measured using ELISA at baseline, 2 hours of ischemia, and 1 hour and 2 hours of reperfusion. SMA blood flow was measured with a Doppler probe at baseline, 10 min, 1 hour, and 2 hours of reperfusion. Histological changes of the intestinal mucosa were examined and graded on a five-point scale in all groups.

RESULTS

In the control group, levels of TNF-alpha, IL-1, and IL-6 were significantly increased during reperfusion (p < 0.05) compared to baseline. Administration of L-arginine and aprotinin led to suppression of the release of TNF-alpha, IL-1, and IL-6 during reperfusion in a statistically significant manner (all p < 0.05). A synergistic or additive effect of L-arginine and aprotinin was not observed. SMA blood flow in the control group was decreased (p > 0.05) during reperfusion compared to baseline. In animals treated with L-arginine and aprotinin, SMA blood flow during reperfusion was significantly increased (p < 0.05) compared to the control group. Histologic examination of the intestinal mucosa was characterized by flattening of the villi and necrosis in the control group. In the treated animals, less severe histological changes were noted.

CONCLUSIONS

Administration of L: -arginine and aprotinin may lead to amelioration of intestinal I/R injury. We did not note a synergistic or additive effect of these two substances. These findings warrant further studies in clinical settings for future treatment efforts.

The effects of moderate hypothermia on energy metabolism and serum inflammatory markers during laparotomy

The objective of this study was to investigate energy metabolism of the gut and liver as well as serum inflammatory cytokines following exploratory laparotomy at moderate hypothermia. Two groups of rats were studied, (n=6-8/group); laparotomy at normothermia for 120 min and laparotomy at hypothermia (32-33 degrees C) for 120 min. Study 1: Intestinal glucose, succinate, lactate, phosphocreatine, and ATP as well as hepatic glucose, succinate, lactate, and ATP were measured in terms of micromole per gram using magnetic resonance spectroscopy. Study 2: Serum levels of TNF-alpha, IL-1beta, LPS-inducible chemokine (LIX), and sICAM-1 were measured by ELISA. Histology of the gut and liver were interpreted. Data are expressed as mean and SEM. In Study 1, laparotomy at hypothermia caused an increase in intestinal glucose levels (0.78+/-0.03 vs. 1.29+/-0.11, P=0.0012) with a decrease in hepatic lactate levels (0.82+/-0.04 vs. 0.44+/-0.06, P<0.001). There were no differences in the other metabolites between the two groups. In Study 2, there were no differences in serum TNF-alpha, IL-1beta, LIX, or sICAM-1 between the two groups. Histological features of the gut and liver among groups were comparable. In conclusion, the intestine and liver react to hypothermia differently. However, levels of high-energy phosphates in both organs are not affected by hypothermia suggesting adequate energy for the organs. It is unlikely that hypothermia induces either systemic inflammatory response or hypoxic damage to the intestine and liver in this model.