Hypothermia and anesthetic postconditioning influence the expression and activity of small intestinal proteins possibly involved in ischemia/reperfusion-mediated events following cardiopulmonary resuscitation

The association of early diarrhea after successful resuscitation following out-of-hospital cardiac arrest with neurological outcome: A retrospective observational study

Gastrointestinal ischemia with reperfusion tissue injury contributes to post-cardiac arrest syndrome. We hypothesized that diarrhea is a symptom of intestinal ischemia/reperfusion injury and investigated whether the occurrence of early diarrhea (≤12 hours) after successful cardiopulmonary resuscitation is associated with an unfavorable neurological outcome.We analyzed data from the Vienna Clinical Cardiac Arrest Registry. Inclusion criteria comprised ≥18 years of age, a witnessed, non-traumatic out-of-hospital cardiac arrest, return of spontaneous circulation (ROSC), initial shockable rhythm, and ST-segment elevation in electrocardiogram after ROSC with consecutive coronary angiography. Patients with diarrhea caused by other factors (e.g., infections, antibiotic treatment, or chronic diseases) were excluded. The primary endpoint was neurological function between patients with or without "early diarrhea" (≤12 hours after ROSC) according to cerebral performance categories.We included 156 patients between 2005 and 2012. The rate of unfavorable neurologic outcome was higher in patients with early diarrhea (67% vs 37%). In univariate analysis, the crude odds ratio for unfavorable neurologic outcome was 3.42 (95% confidence interval, 1.11-10.56, P = .03) for early diarrhea. After multivariate adjustment for traditional prognostication markers the odds ratio of early diarrhea was 5.90 (95% confidence interval, 1.28-27.06, P = .02).In conclusion, early diarrhea within 12 hours after successful cardiopulmonary resuscitation was associated with an unfavorable neurological outcome.

Fast hypothermia induced by extracorporeal circuit cooling alleviates renal and intestinal injury after cardiac arrest in swine

BACKGROUND

Continuous renal replacement therapy (CRRT) was currently demonstrated to be an effective way to induce fast hypothermia and had proective effects on cardiac dysfunction and brain damage after cardiac pulmonary resuscitation (CPR). In the present study, we aimed to investigate the influence of extracorporeal circuit cooling using CRRT on renal and intestinal damage after CPR based on a porcine model.

METHODS

32 pigs were subjected to ventricular fibrillation for 8 min, followed by CPR for 5 min before defibrillation. All were randomized to receive extracorporeal circuit cooling using CRRT (CRRT, n = 9), surface cooling (SC, n = 9), normothermia (NT, n = 9) or sham control (n = 5) at 5 min post resuscitation. Pigs in the CRRT group were cooled by 8-h CRRT cooling with the infusion line initially submerged in 4 °C of ice water and 16-h SC, while in the SC group by a 24-h SC. Temperatures were maintained at a normal range in the other two groups. Biomarkers in serum were measured at baseline and 1, 3, 6, 12, 24 and 30 h post resuscitation to assess organ functions. Additionally, tissues of kidney and intestine were harvested, from which the degree of tissue inflammation, oxidative stress, and apoptosis levels were analyzed.

RESULTS

The blood temperature decreased faster by extracorporeal circuit cooling using CRRT than SC (9.8 ± 1.6 vs. 1.5 ± 0.4 °C/h, P < 0.01). Post-resuscitation renal and intestinal injury were significantly improved in the 2 hypothermic groups compared to the NT group. And the improvement was significantly greater in animals received extracorporeal circuit cooling than those received surface cooling, from both the results of biomarkers in serum and pathological evidence.

CONCLUSION

Fast hypothermia induced by extracorporeal circuit cooling was superior to. surface cooling in mitigating renal and intestinal injury post resuscitation.

Preconditioning hippocampal slices with hypothermia promotes rapid tolerance to hypoxic depolarization and swelling: Mediation by erythropoietin

We suggested previously that hippocampal slices were protected from hypoxic depolarization and swelling by preincubating them at room temperature (Kreisman et al., 2000). We postulated that hypothermic preconditioning induced tolerance in our slices, which protected against hypoxic depolarization and swelling. Control hippocampal slices were incubated at 34-35 °C for two hours and the response to 10 min of severe hypoxia was compared to slices which were preconditioned for two hours at room temperature (22-23 °C) prior to warming to 34-35 °C. Recordings of the extracellular DC potential provided an index of tissue depolarization and changes in tissue light transmittance provided an index of swelling. Hypothermic preconditioning significantly reduced hypoxia-induced swelling, particularly in CA3 and the dentate inner blade. Since erythropoietin (EPO) had been shown to mediate hypoxic preconditioning, we tested whether EPO also mediated hypothermic preconditioning in our slices. Recombinant rat EPO (1-10 micromolar) mitigated hypoxia-induced swelling and depolarization in dentate inner blade of unconditioned slices in a dose-dependent manner. We also blocked the protective effects of hypothermic preconditioning on hypoxic depolarization and swelling in the inner blade of the dentate gyrus by administering soluble EPO receptor in the bath and treating slices with wortmannin to block phosphorylation of PI3 kinase, a critical step in the activation of the downstream neuroprotectant, Akt. These results suggest that EPO mediates tolerance to hypoxic depolarization and swelling induced by hypothermic preconditioning. They also emphasize that various preincubation protocols used in experiments with hippocampal slices may differentially affect basal electrophysiological and metabolic properties of those slices.

Effect of ulinastatin combined with mild therapeutic hypothermia on intestinal barrier dysfunction following cardiopulmonary resuscitation in rats

The aim of the present study was to investigate the effect of ulinastatin (UTI) alone or combined with mild therapeutic hypothermia (MTH) on intestinal barrier dysfunction following cardiopulmonary resuscitation (CPR) in rats. A total of 25 adult male Sprague-Dawley rats were randomly organized into five groups: Sham; control; UTI; MTH; and the combined group. The latter four groups were induced with the asphyxiated cardiac arrest rat model and treated with different interventions. After 6 h of treatment, the intestinal tissues of the rats were examined by electron microscopy, and the levels of intestinal malondialdehyde (MDA) and superoxide dismutase (SOD) were determined. The results of the present study indicated that the target temperature had successfully been attained in MTH and the combined group, and the other three groups of rats all survived at a normal temperature. In the rats treated with UTI or MTH, the epithelial cells exhibited pathological changes in their tight junctions and epithelial cell surface microvilli compared with the sham group. In the rats treated with a combination of UTI and MTH, whilst the epithelial cells exhibited a few slight changes, including mitochondrial edema, they were largely similar to the normal epithelial cells. However, there were significant differences in the levels of MDA and SOD between the different treatment groups. UTI combined with MTH may serve a protective role by suppressing oxidative stress in the small intestinal mucosa following CPR in rats compared with either UTI or MTH treatment alone.

The insights into molecular pathways of hypoxia-inducible factor in the brain

The objectives of this present work were to review recent developments on the role of hypoxia-inducible factor (HIF) in the survival of cells under normoxic versus hypoxic and inflammatory brain conditions. The dual nature of HIF effects appears well established, based on the accumulated evidence of HIF playing both the role of adaptive factor and mediator of cell demise. Cellular HIF responses depend on pathophysiological conditions, developmental phase, comorbidities, and administered medications. In addition, HIF-1α and HIF-2α actions may vary in the same tissues. The multiple roles of HIF in stem cells are emerging. HIF not only regulates expression of target genes and thereby influences resultant protein levels but also contributes to epigenetic changes that may reciprocally provide feedback regulations loops. These HIF-dependent alterations in neurological diseases and its responses to treatments in vivo need to be examined alongside with a functional status of subjects involved in such studies. The knowledge of HIF pathways might be helpful in devising HIF-mimetics and modulating drugs, acting on the molecular level to improve clinical outcomes, as exemplified here by clinical and experimental data of selected brain diseases, occasionally corroborated by the data from disorders of other organs. Because of complex role of HIF in brain injuries, prospective therapeutic interventions need to differentially target HIF responses depending on their roles in the molecular mechanisms of neurologic diseases.

Anesthetic postconditioning plus hypothermia following cardiopulmonary resuscitation protects the myocardial ultrastructure by modulating inflammatory events in rabbits

Myocardial ischemia/reperfusion (I/R) injury is usually caused by resuscitation following cardiac arrest. The aim of the present study was to investigate the influence of sevoflurane postconditioning on the myocardial ultrastructure induced by cardiac arrest and successful resuscitation in mature rabbits. A total of 32 rabbits were randomly and equally divided into an I/R group (I/R group), a hypothermia group (H group), a sevoflurane postconditioning group (S group), and hypothermia plus sevoflurane postconditioning group (H + S group). Interleukin (IL)-8 and IL-10 levels in blood were evaluated at four different time points (1 h pre-ischemia: T1; 1, 2 and 3 h after reperfusion: T2, T3 and T4, respectively). The myocardial ultrastructure was evaluated by microscope after the rabbits were scarified. Plasma levels of IL-8 and IL-10 increased in all of the groups from T2. However, compared with the I/R group from T3 and T4, downregulation of IL-8 was significant in the S and H + S groups (P<0.05), and the result of intra-group comparison demonstrated that the level of serum IL-8 was the lowest in the H + S group (P<0.05). By contrast, upregulation of IL-10 was significantly higher in the S and H + S groups (P<0.05), particularly in the H + S group. Notably, ultrastructure damage of the myocardium was significantly lighter, and the structural integrity of the myocardium in the H + S group was better when compared with that of the S group. Thus, sevoflurane postconditioning plus hypothermia protected the myocardial ultrastructure following cardiopulmonary resuscitation by suppressing inflammatory effects.

Non-occlusive mesenteric ischaemia in out of hospital cardiac arrest survivors

BACKGROUND AND AIM OF THE STUDY

Non-occlusive mesenteric ischaemia (NOMI) is characterised by hypoperfusion of the intestines without evidence of mechanical obstruction, potentially leading to extensive ischaemia and necrosis. Low cardiac output appears to be a major risk factor. Cardiopulmonary resuscitation aims at restoring blood flow after cardiac arrest. However, post restoration of spontaneous circulation, myocardial stunning limits immediate recovery of sufficient cardiac function. Since after successful cardiopulmonary resuscitation patients are often ventilated and sedated, NOMI might be underdiagnosed and potentially life-saving treatment delayed.

MATERIAL AND METHODS

A prospectively maintained multi-purpose cohort of out of hospital cardiac arrest survivors, who had successful restoration of spontaneous circulation, was used for this retrospective database analysis. Patients' charts were screened for clinical, radiological or pathological evidence of NOMI and clinical data were collected.

RESULTS

Between 2000 and 2014, 1780 patients who were successfully resuscitated after out of hospital cardiac arrest were screened for NOMI. Twelve patients (0.68 %) suffered from NOMI and six of those died (50 %). Patients suffering from NOMI tended to have a longer duration until restoration of spontaneous circulation (27 vs. 20 min, p=0.128) and had significantly higher lactate (14 mmol/l vs. 8 mmol/l, p=0.002) and base deficit levels at admission (-17 vs. -10, p=0.012). Median leukocyte counts in NOMI patients peaked at the day of diagnosis.

CONCLUSION

NOMI is a rare but life-threatening and potentially curable complication following successful cardiopulmonary resuscitation. Lactate and base deficit at admission could help to identify patients at risk for developing NOMI who might benefit from increased clinical attention.

Pretreatment With Erythropoietin Attenuates Intestinal Ischemia Reperfusion Injury by Further Promoting PI3K/Akt Signaling Activation

BACKGROUND

Erythropoietin (EPO) has been shown to be beneficial in resolution of acute inflammation and intestinal ischemia/reperfusion (IR) injury is featured by the excessive immune response. The current research is designed to evaluate the effect and potential mechanisms of EPO on the intestinal IR injury. Therefore, the effect of EPO on intestinal IR injury was examined by the change of intestinal histology; the expression of pro-inflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interferon γ (IFN-γ); and the protein levels of EPOR, p-EPOR, p85, p-p85, Akt, p-Akt, IκΒ-α, p-p65, and p65.

MATERIALS AND METHODS

Thirty male Sprague-Dawley rats were randomly divided into three groups: sham group (sham), IR-saline group (IRI), and the IR-EPO group (EPO). Rats were treated with EPO (5000 U/kg) 1 hour before IR induction. A rat model of IR injury was established by ligating the superior mesenteric artery for 30 minutes, followed by reperfusion for 1 hour. Intestinal histology, pro-inflammatory cytokines, and mediators were assessed. The effect of EPO on PI3K/Akt/NF-κB signaling and EPOR were also measured.

RESULTS

EPO significantly decreased the pathologic changes of intestinal and reduced the elevation of pro-inflammatory cytokines TNF-α, IL-1β, and IFN-γ in intestinal and serum caused by IR which was associated with suppressing NF-κB activation by further promoting activation of PI3K/Akt signaling.

CONCLUSIONS

EPO ameliorated the acute intestinal injury caused by IR, which was associated with further activating PI3K/Akt signaling to suppress NF-κΒ-mediating inflammation. Our findings suggest that EPO could be useful for preventing IR-induced intestinal injury.

Protective effects of epigallocatechin-3-gallate on intestinal ischemia reperfusion injury through enhanced activation of PI3K/Akt pathway in rats

Inflammation plays a critical role in intestinal ischemia reperfusion injury (IRI). Epigallocatechin-3-gallate (EGCG) has been demonstrated to possess anti-inflammatory effect. This study examined the effect of EGCG on intestinal IRI and explored the possible mechanisms. Male Wistar rats were randomly divided into three groups: sham-operated group (Sham), IRI control group (IRI) and IRI-EGCG group (EGCG). Rats in IRI-EGCG group were administered dissolved EGCG in drinking water (0.4 mg/mL) for 14 days prior to IRI induction. A rat model of intestinal IRI was established by ligating the superior mesenteric artery (SMA) for 30 min, followed by reperfusion for 1 h. Intestinal histology, pro-inflammatory cytokines and mediators were examined and the effect of EGCG on PI3K/Akt signalling was assessed. EGCG significantly alleviated the pathological changes of the intestine and suppressed the IRI-induced up-regulation of TNF-α, IL-1 and IL-6 mRNA and protein expression in the serum and intestine. The mechanism might be that EGCG enhanced the activation of PI3K/Akt signalling pathway. In conclusion, the administration of EGCG can significantly mitigate the acute intestinal IRI in rats by enhancing the activation of PI3K/Akt signalling pathway to suppress inflammatory response and might be a promising alternative for the prevention or treatment of intestinal IRI in the clinical practice.

Activities of cardiac tissue matrix metalloproteinases 2 and 9 are reduced by remote ischemic preconditioning in cardiosurgical patients with cardiopulmonary bypass

Background

Transient episodes of ischemia in a remote organ or tissue (remote ischemic preconditioning, RIPC) can attenuate myocardial injury. Myocardial damage is associated with tissue remodeling and the matrix metalloproteinases 2 and 9 (MMP-2/9) are crucially involved in these events. Here we investigated the effects of RIPC on the activities of heart tissue MMP-2/9 and their correlation with serum concentrations of cardiac troponin T (cTnT), a marker for myocardial damage.

Methods

In cardiosurgical patients with cardiopulmonary bypass (CPB) RIPC was induced by four 5 minute cycles of upper limb ischemia/reperfusion. Cardiac tissue was obtained before as well as after CPB and serum cTnT concentrations were measured. Tissue derived from control patients (N = 17) with high cTnT concentrations (≥0.32 ng/ml) and RIPC patients (N = 18) with low cTnT (≤0.32 ng/ml) was subjected to gelatin zymography to quantify MMP-2/9 activities.

Results

In cardiac biopsies obtained before CPB, activities of MMP-2/9 were attenuated in the RIPC group (MMP-2: Control, 1.13 ± 0.13 a.u.; RIPC, 0.71 ± 0.12 a.u.; P < 0.05. MMP-9: Control, 1.50 ± 0.16 a.u.; RIPC, 0.87 ± 0.14 a.u.; P < 0.01), while activities of the pro-MMPs were not altered (P > 0.05). In cardiac biopsies taken after CPB activities of pro- and active MMP-2/9 were not different between the groups (P > 0.05). Spearman’s rank tests showed that MMP-2/9 activities in cardiac tissue obtained before CPB were positively correlated with postoperative cTnT serum levels (MMP-2, P = 0.016; MMP-9, P = 0.015).

Conclusions

Activities of MMP-2/9 in cardiac tissue obtained before CPB are attenuated by RIPC and are positively correlated with serum concentrations of cTnT. MMPs may represent potential targets for RIPC mediated cardioprotection.

Trial registration

ClinicalTrials.gov identifier NCT00877305.

Markers of intestinal injury are associated with endotoxemia in successfully resuscitated patients

AIMS

Gut dysfunction is suspected to play a major role in the pathophysiology of post-resuscitation disease through an increase in intestinal permeability and endotoxin release. However this dysfunction often remains occult and is poorly investigated. The aim of this pilot study was to explore intestinal failure biomarkers in post-cardiac arrest patients and to correlate them with endotoxemia.

METHODS

Following resuscitation after cardiac arrest, 21 patients were prospectively studied. Urinary intestinal fatty acid-binding protein (IFABP), which marks intestinal permeability, plasma citrulline, which reflects the functional enterocyte mass, and whole blood endotoxin were measured at admission, days 1-3 and 6. We explored the kinetics of release and the relationship between IFABP, citrulline and endotoxin values.

RESULTS

IFABP was extremely high at admission and normalized at D3 (6668 pg/mL vs 39 pg/mL, p=0.01). Lowest median of citrulline (N=20-40 μmol/L) was attained at D2 (11 μmol/L at D2 vs 24 μmol/L at admission, p=0.01) and tended to normalize at D6 (21 μmol/L). During ICU stay, 86% of patients presented a detectable endotoxemia. Highest endotoxin level was positively correlated with highest IFABP level (R(2)=0.31, p=0.01) and was inversely correlated with lowest plasma citrulline levels (R(2)=0.55, p<0.001). Endotoxin levels increased between admission and D2 in patients with post-resuscitation shock, whereas it decreases in patients with no shock (median +0.33 EU vs -0.19 EU, p=0.03). Highest endotoxin level was positively correlated with D3 SOFA score (R(2)=0.45, p=0.004).

CONCLUSION

Biomarkers of intestinal injury are altered after cardiac arrest and are associated with endotoxemia. This could worsen post-resuscitation shock and organ failure.

Ischemic postconditioning at the initiation of cardiopulmonary resuscitation facilitates functional cardiac and cerebral recovery after prolonged untreated ventricular fibrillation

OBJECTIVES

Ischemic postconditioning (PC) with "stuttering" reintroduction of blood flow after prolonged ischemia has been shown to offer protection from ischemia reperfusion injury to the myocardium and brain. We hypothesized that four 20-s pauses during the first 3 min of standard CPR would improve post resuscitation cardiac and neurological function, in a porcine model of prolonged untreated cardiac arrest.

METHODS

18 female farm pigs, intubated and isoflurane anesthetized had 15 min of untreated ventricular fibrillation followed by standard CPR (SCPR). Nine animals were randomized to receive PC with four, controlled, 20-s pauses, during the first 3 min of CPR (SCPR+PC). Resuscitated animals had echocardiographic evaluation of their ejection fraction after 1 and 4 h and a blinded neurological assessment with a cerebral performance category (CPC) score assigned at 24 and 48 h. All animals received 12 h of post resuscitation mild therapeutic hypothermia.

RESULTS

SCPR+PC animals had significant improvement in left ventricular ejection fraction at 1 and 4 h compared to SCPR (59±11% vs. 35±7% and 55±8% vs. 31±13% respectively, p<0.01). Neurological function at 24h significantly improved with SCPR+PC compared to SCPR alone (CPC: 2.7±0.4 vs. 3.8±0.4 respectively, p=0.003). Neurological function significantly improved in the SCPR+PC group at 48 h and the mean CPC score of that group decreased from 2.7±0.4 to 1.7±0.4 (p<0.00001).

CONCLUSIONS

Ischemic postconditioning with four 20-s pauses during the first 3 min of SCPR improved post resuscitation cardiac function and facilitated neurological recovery after 15 min of untreated cardiac arrest in pigs.