Mesenteric hemodynamic response to circulatory shock

Laparoscopic Cholecystectomy in Cardiogenic Shock And Heart Failure

Background: Patients with cardiogenic shock (CS) or heart failure can develop ischemic cholecystitis from a systemic low-flow state. Cholecystectomy in high-risk patients is controversial. Percutaneous cholecystostomy tube (PCT) is often the chosen intervention; however, data on PCT as definitive treatment are conflicting. Data on cholecystectomy in these patients are limited. This study discusses outcomes following laparoscopic cholecystectomy (LC) in this patient population. Methods: This is a retrospective review of patients who underwent LC from 2015 to 2019 while hospitalized for CS or heart failure. Surgical services are provided by fellowship-trained minimally invasive surgeons at a single, academic, tertiary-care center. Patient characteristics are reported as frequencies' percentages for categorical variables. Odds ratio is used to determine the association between comorbidities and complications. Results: Twenty-four patients underwent LC. Around 83% were white and 79% were male. Many were anticoagulated (88%), with Class IV heart failure (63%), and required vasopressors (46%) at the time of surgery. Fourteen of 24 (58%) had at least one circulatory device at the time of surgery: extracorporeal membrane oxygenation, left ventricular assist device, Impella, tandem heart, and total artificial heart. Four patients (17%) had PCT preoperatively. Fifteen days were the average interval between diagnosis and surgery. Pneumoperitoneum was tolerated by all, and 0% converted to open. Most common complication was bleeding (52%). Nine patients (37.5%) underwent 21 reoperations, one of which (4%) was related to cholecystectomy. Mortality occurred in 5 patients (20.8%); interval between cholecystectomy and mortality ranged 6-30 days. Conclusion: Although high risk, LC is a treatment option in patients with ischemic cholecystitis at risk for death from sepsis.

Nutritional support in the cardiac intensive care unit

Optimal care of critically ill patients in the cardiac intensive care unit includes adequate nutritional support. This review highlights the high prevalence of malnutrition in acute heart failure, acute coronary syndrome, cardiogenic shock, and post-cardiac arrest and its adverse impact on prognosis. There is a lack of robust evidence regarding appropriate nutritional support in this patient population. Initiation of nutritional support with a comprehensive assessment of the patient's nutritional status is critical. High-risk cardiac patients who are not critically ill can receive oral nutrition adapted to individual risk factors or deficiencies, although overfeeding should be avoided in the acute phase. For critically ill patients at risk of or with malnutrition on admission, general principles include initiation of nutritional support within 48 h of admission, preference for enteral over parenteral nutrition, preference for hypocaloric nutrition in the first week of intensive care unit admission, and adequate micronutrient supplementation. Enteral nutrition in haemodynamically unstable patients carries a risk, albeit low, of intestinal ischaemia. In the case of malnutrition, the risk of refeeding syndrome should always be considered.

Modifications of peripheral perfusion in patients with vasopressor-dependent septic shock treated with polymyxin B-direct hemoperfusion

Abnormal peripheral perfusion (PP) worsens the prognosis of patients with septic shock. Polymyxin B-direct hemoperfusion (PMX-DHP) increases blood pressure and reduces vasopressor doses. However, the modification of PP following administration of PMX-DHP in patients with vasopressor-dependent septic shock have not yet been elucidated. A retrospective exploratory observational study was conducted in patients with septic shock treated with PMX-DHP. Pulse-amplitude index (PAI), vasoactive inotropic score (VIS), and cumulative fluid balance data were extracted at PMX-DHP initiation (T0) and after 24 (T24) and 48 (T48) h. Changes in these data were analyzed in all patients and two subgroups (abnormal PP [PAI < 1] and normal PP [PAI ≥ 1]) based on the PAI at PMX-DHP initiation. Overall, 122 patients (abnormal PP group, n = 67; normal PP group, n = 55) were evaluated. Overall and in the abnormal PP group, PAI increased significantly at T24 and T48 compared with that at T0, with a significant decrease in VIS. Cumulative 24-h fluid balance after PMX-DHP initiation was significantly higher in the abnormal PP group. PMX-DHP may be an effective intervention to improve PP in patients with abnormal PP; however, caution should be exercised as fluid requirements may differ from that of patients with normal PP.

Utilizing Near-Infrared Spectroscopy to Identify Pediatric Trauma Patients Needing Lifesaving Interventions: A Prospective Study

OBJECTIVES

The aim of this study was to prospectively investigate the role of near-infrared spectroscopy (NIRS) in identifying pediatric trauma patients who required lifesaving interventions (LSIs).

METHODS

Prospective cohort study of children age 0 to 18 years who activated the trauma team response between August 15, 2017, and February 12, 2019, at a large, urban pediatric emergency department (ED).The relationship between the lowest somatic NIRS saturation and the need for LSIs (based on published consensus definition) was investigated. Categorical variables were analyzed by χ 2 test, and continuous variables were analyzed by Student t test.

RESULTS

A total of 148 pediatric trauma patients had somatic NIRS monitoring and met the inclusion criteria. Overall, 65.5% were male with a mean ± SD age of 10.9 ± 6.0 years. Injuries included 67.6% blunt trauma and 28.4% penetrating trauma with mortality of 3.4% (n = 5). Overall, the median lowest somatic NIRS value was 72% (interquartile range, 58%-88%; range, 15%-95%), and 43.9% of patients had a somatic NIRS value <70%. The median somatic NIRS duration recorded was 11 minutes (interquartile range, 7-17 minutes; range, 1-105 minutes). Overall, 36.5% of patients required a LSI including 53 who required a lifesaving procedure, 17 required blood products, and 17 required vasopressors. Among procedures, requiring a thoracostomy was significant.Pediatric trauma patients with a somatic NIRS value <70% had a significantly increased odds of requiring a LSI (odds ratio, 2.11; 95% confidence interval, 1.07-4.20). Somatic NIRS values <70% had a sensitivity and specificity of 56% and 63%, respectively.

CONCLUSIONS

Pediatric trauma patients with somatic NIRS values <70% within 30 minutes of ED arrival have an increased odds of requiring LSIs. Among LSIs, pediatric trauma patients requiring thoracostomy was significant. The role of NIRS in incrementally improving the identification of critically injured children in the ED and prehospital setting should be evaluated in larger prospective multicenter studies.

Ischemic Pancreatitis Is an Important Cause of Acute Pancreatitis in the Intensive Care Unit

BACKGROUND

Ischemic pancreatitis (IP) has mainly been described in case reports. The aims of the study were to assess the frequency, clinical characteristics and outcomes in patients with IP among patients hospitalized in the intensive care unit (ICU) for acute pancreatitis (AP).

METHODS

All patients with first time AP between 2011 and 2018 in the ICU of Landspitali Hospital, Iceland were retrospectively included. IP as an etiology required a clinical setting of circulatory shock, arterial hypotension, hypovolemia and/or arterial hypoxemia [PaO 2 of 60 mm Hg (8.0 kPa), or less] before the diagnosis of AP without prior history of abdominal pain to this episode. Other causes of AP were ruled out. IP patients were compared with patients with AP of other etiologies, also hospitalized in the ICU.

RESULTS

Overall 67 patients with AP were identified (median age 60 y, 37% females), 31% idiopathic, 24% alcoholic, 22% IP, 15% biliary, and 8% other causes. Overall, 15 (22%) fulfilled the predetermined criteria for IP, 9 males (64%), median age 62 years (interquartile range: 46 to 65). IP was preceded mainly by systemic shock (73%). Other causes included dehydration, hypoxia, or vessel occlusion to the pancreas. Necrosis of the pancreas was rare with one patient requiring pancreatic necrosectomy. Inpatient mortality was higher among patients with IP than in other patients with AP (33% vs. 14%, P =0.12).

CONCLUSIONS

IP was found in a significant proportion of AP patients hospitalized in the ICU. The main causes of IP were systemic shock and hypoxia. IP was associated with ∼30% mortality.

Prognostic potential of liver injury in patients with dilated cardiomyopathy: a retrospective study

Background

Liver injury (LI) has been frequently observed in patients with dilated cardiomyopathy (DCM), whereas its prognostic value remains blurry. We attempted to appraise the prognostic effect of LI in patients with DCM.

Methods

This retrospective study included 523 patients with DCM. LI was defined as a threefold increase in aspartate transaminase (≥ 135 U/L) or alanine transaminase (≥ 180 U/L) or a twofold increase in total bilirubin (≥ 41 umol/L) during hospitalization. The population was segmented into non-liver injury (NLI) group and LI group based on liver function test data. To balance differences in covariates at baseline, 1:1 propensity score matching (PSM) was performed.

Results

Patients with LI had lower survival rate, compared with those with NLI (44.6% vs. 73.8%, P < 0.001). Similar results were also found in age (age > 50, 39.6% vs. 70.9%, P < 0.001; age ≤ 50, 51.3% vs. 79.5%, P < 0.001) and gender stratified analysis (male, 46.2% vs. 74.4%, P < 0.001; female 35.7% vs. 72.0%, P = 0.001). After PSM, the survival rate of patients with LI remained lower than those with NLI (44.6% vs. 64.1%, P = 0.019). Multivariable Cox regression analysis manifested that LI (hazard ratio [HR]: 1.692, 95% confidence interval [CI] 1.194–2.398, P = 0.003; HR: 1.675, 95% CI 1.078–2.604, P = 0.022, respectively) showed potent predictive effect on all-cause mortality in patients with DCM, both before and after PSM.

Conclusions

The occurrence of LI herald adverse outcomes in patients with DCM and attention to LI may be conducive to risk stratification and management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40001-022-00876-9.

Enteral Nutrition in Critically Ill Patients Under Vasoactive Drug Therapy. The NUTRIVAD Study

BACKGROUND

Enteral nutrition (EN) in critically ill patients requiring vasoactive drug (VAD) support is controversial. This study assesses the tolerability and safety of EN in such patients.

METHODS

This prospective observational study was conducted in 23 ICUs over 30 months. Inclusion criteria were a need for VAD and/or mechanic circulatory support (MCS) over a minimum of 48 h, a need for at least 48 h of mechanical ventilation, an estimated life expectancy longer than 72 h, and at least 72 h of ICU stay. Patients with refractory shock were excluded. EN was performed according to established protocols during which descriptive, daily hemodynamic and efficacy and safety data were collected. An independent research group conducted the statistical analysis.

RESULTS

Of 200 patients included, 30 (15%) required MCS and 145 (73%) met early multiorgan dysfunction criteria. Mortality was 24%. Patients needed a mean dose of norepinephrine in the first 48 h of 0.71 μg/kg/min (95%CI: 0.63-0.8) targeting a mean arterial pressure of 68 mmHg (95%CI: 67-70) during the first 48 h. EN was started 34 h (95%CI: 31-37) after ICU admission. Mean energy and protein delivered by EN/patient/day were 1159 Kcal (95%CI: 1098-1220) and 55.6 g (52.4-58.7) respectively. Daily energy balance during EN/patient/day was -432 (95%CI: -496 to -368). 154 (77%) patients experienced EN-related complications. However, severe complications such as mesenteric ischemia were recorded in only 1 patient (0.5%).

CONCLUSIONS

EN in these patients seems feasible, safe and unrelated to serious complications. Reaching the energy target only through EN is difficult.

CLINICAL RELEVANCY STATEMENT

Enteral nutrition (EN) in critically ill patients requiring vasoactive drugs (VAD) is currently a subject of controversy. Factors such as when to start EN, dosing, monitoring, or whether to avoid EN altogether are a real challenge because of its link to a risk of bowel ischemia. We describe our experience with EN in 200 critically ill patients on mechanical ventilation and requiring VAD. Under adequate supervision, EN proved feasible and safe. Our findings require confirmation in clinical intervention trials. This article is protected by copyright. All rights reserved.

Utilizing Near-Infrared Spectroscopy (NIRS) to Identify Pediatric Trauma Patients Needing Lifesaving Interventions (LSIs): A Retrospective Study

OBJECTIVES

The aim of this study was to investigate the role of near-infrared spectroscopy (NIRS) in identifying pediatric trauma patients who required lifesaving interventions (LSIs).

METHODS

Retrospective chart review of children age 0 to 18 years who activated the trauma team response between January 1, 2015 and August 14, 2017, at a large, urban pediatric emergency department. The lowest somatic NIRS saturation and the need for LSIs (based on published consensus definition) were abstracted from the chart. χ2 and descriptive statistics were used for analysis.

RESULTS

The charts of 84 pediatric trauma patients were reviewed. Overall, 80% were boys with a mean age of 10.4 years (SD, 6.2 years). Injuries included 56% blunt trauma and 36% penetrating trauma with mortality of 10.7% (n = 9). Overall, the median lowest NIRS value was 67% (interquartile range, 51-80%; range, 15%-95%) and 54.8% of the patients had a NIRS value less than 70%. The median somatic NIRS duration recorded was 12 minutes (interquartile range, 6-17 minutes; range, 1-59 minutes). Overall, 50% of patients required a LSI, including 39 who required a lifesaving procedure, 11 required blood products, and 14 required vasopressors. Pediatric trauma patients with NIRS less than 70% had a significantly increased odds of requiring a LSI (odds ratio, 2.67; 95% confidence interval, 1.10-6.47). NIRS less than 70% had a sensitivity and specificity of 67% and 57% respectively.

CONCLUSIONS

Pediatric trauma patients with somatic NIRS less than 70% within 30 minutes of emergency department arrival are associated with the need for LSIs. Continuous NIRS monitoring in the pediatric trauma population should be evaluated prospectively.

Association of Small Intestinal Bacterial Overgrowth With Heart Failure and Its Prediction for Short-Term Outcomes

Background Small intestinal bacterial overgrowth (SIBO) is a common pathological condition of intestinal microbiota. The prevalence of SIBO and its prognostic value in patients with heart failure (HF) are unknown. Methods and Results A total of 287 patients tested for SIBO using lactulose hydrogen-methane breath test were evaluated. At least 1 of the following criteria fulfilled was SIBO positive: patients with fasting hydrogen level ≥20 parts per million (ppm) or a ≥20 ppm rise in hydrogen by 90 minutes were diagnosed with SIBO (H₂) positive; and patients with methane levels ≥10 ppm at any test point were diagnosed with SIBO (CH₄) positive. The association between SIBO and the composite of cardiovascular death and HF rehospitalization was investigated. In 287 consecutive patients with HF, 128 (45%) were positive for SIBO. Our result showed SIBO increased the risk of HF rehospitalization in patients with HF with reduced ejection fraction (P<0.001), and the risk of cardiovascular death in patients with HF with preserved EF (P=0.011). SIBO was an independent risk factor of primary end point in patients with HF (hazard ratio [HR], 2.13; 95% CI; 1.26-3.58; P=0.005). In addition, SIBO (CH₄) showed a prognostic value on adverse outcomes (HR, 2.35; 95% CI, 1.38-4.02; P<0.001), whereas the association between SIBO (H₂) and outcomes was not statistically significant. Conclusions There was high prevalence of SIBO in patients with HF, and SIBO was independently associated with poor outcomes. Proactive treatment for SIBO may provide extra benefit for patients with HF.

Severe acute pancreatitis: capillary permeability model linking systemic inflammation to multiorgan failure

Severe acute pancreatitis (SAP) includes persistent systemic inflammation (SIRS) and multiorgan failure (MOF). The mechanism of transition from SIRS to MOF is unclear. We developed a fluid compartment model and used clinical data to test predictions. The model includes vascular, interstitial and "third-space" compartments with variable permeability of plasma proteins at the capillaries. Consented patients from University of Pittsburgh Medical Center Presbyterian Hospital were studied. Preadmission and daily hematocrit (HCT), blood urea nitrogen (BUN), creatine (Cr), albumin (Alb), and total protein (TP) were collected, and nonalbumin plasma protein (NAPP = TP minus the Alb) was calculated. Subjects served as their own controls for trajectory analysis. Of 57 SAP subjects, 18 developed MOF (5 died), and 39 were non-MOF (0 died). Compared with preadmission levels, admission HCT increased in MOF +5.00 [25%-75% interquartile range, IQR] versus non-MOF -0.10 [-1.55, 1.40] (P < 0.002) with HCT > +3 distinguishing MOF from non-MOF (odds ratio 17.7, P = 0.014). Preadmission Alb fell faster in MOF than non-MOF (P < 0.01). By day 2, TP and NAPP dropped in MOF but not non-MOF (P < 0.001). BUN and Cr levels increased in MOF (P = 0.001), but BUN-to-Cr ratios remained constant. Pancreatic necrosis was more common in MOF (56%) than non-MOF (23%). Changing capillary permeability to allow loss of NAPP in this model predicts loss of plasma oncotic pressure and reduced vascular volume, hypotension with prerenal azotemia and acute kidney dysfunction, pancreas necrosis, and pulmonary edema from capillary leak in the lung with acute respiratory distress syndrome. Sequential biomarker analysis in humans with or without MOF is consistent with this model. This study is registered on https://clinicaltrials.gov at NCT03075605.NEW & NOTEWORTHY Acute pancreatitis is a sudden inflammatory response to pancreatic injury that may spread to systemic inflammation, multiorgan failure, and death in some patients. With the use of the predictions of a new mechanistic model, we compared patients with severe acute pancreatitis with or without multiorgan failure. All biomarkers of capillary leak and clinical features of multiorgan failure were accurately predicted. This provides a new paradigm for understanding and developing new treatments for patients with severe acute pancreatitis.

Castro M, Sidoli S, Schwämmle V, Luz IS, Roepstorff P, Fontes W. Phosphoproteomic Analysis of Rat Neutrophils Shows the Effect of Intestinal Ischemia/Reperfusion and Preconditioning on Kinases and Phosphatases

Intestinal ischemia reperfusion injury (iIRI) is a severe clinical condition presenting high morbidity and mortality worldwide. Some of the systemic consequences of IRI can be prevented by applying ischemic preconditioning (IPC), a series of short ischemia/reperfusion events preceding the major ischemia. Although neutrophils are key players in the pathophysiology of ischemic injuries, neither the dysregulation presented by these cells in iIRI nor the protective effect of iIPC have their regulation mechanisms fully understood. Protein phosphorylation, as well as the regulation of the respective phosphatases and kinases are responsible for regulating a large number of cellular functions in the inflammatory response. Moreover, in previous work we found hydrolases and transferases to be modulated in iIR and iIPC, suggesting the possible involvement of phosphatases and kinases in the process. Therefore, in the present study, we analyzed the phosphoproteome of neutrophils from rats submitted to mesenteric ischemia and reperfusion, either submitted or not to IPC, compared to quiescent controls and sham laparotomy. Proteomic analysis was performed by multi-step enrichment of phosphopeptides, isobaric labeling, and LC-MS/MS analysis. Bioinformatics was used to determine phosphosite and phosphopeptide abundance and clustering, as well as kinases and phosphatases sites and domains. We found that most of the phosphorylation-regulated proteins are involved in apoptosis and migration, and most of the regulatory kinases belong to CAMK and CMGC families. An interesting finding revealed groups of proteins that are modulated by iIR, but such modulation can be prevented by iIPC. Among the regulated proteins related to the iIPC protective effect, Vamp8 and Inpp5d/Ship are discussed as possible candidates for control of the iIR damage.

Circulatory Failure among Hospitalizations for Heatstroke in the United States

Background: This study aimed to assess the risk factors and the association of circulatory failure with treatments, complications, outcomes, and resource utilization in hospitalized patients for heatstroke in the United States. Methods: Hospitalized patients with a principal diagnosis of heatstroke were identified in the National Inpatient Sample dataset from the years 2003 to 2014. Circulatory failure, defined as any type of shock or hypotension, was identified using hospital diagnosis codes. Clinical characteristics, in-hospital treatment, complications, outcomes, and resource utilization between patients with and without circulatory failure were compared. Results: A total of 3372 hospital admissions primarily for heatstroke were included in the study. Of these, circulatory failure occurred in 393 (12%) admissions. Circulatory failure was more commonly found in obese patients, but less common in older patients aged ≥60 years. The need for mechanical ventilation, blood transfusion, and renal replacement therapy were higher in patients with circulatory failure. Hyperkalemia, hypocalcemia, metabolic acidosis, metabolic alkalosis, sepsis, ventricular arrhythmia or cardiac arrest, renal failure, respiratory failure, liver failure, neurological failure, and hematologic failure were associated with circulatory failure. The in-hospital mortality was 7.1-times higher in patients with circulatory failure. The length of hospital stay and hospitalization costs were higher when circulatory failure occurred while in the hospital. Conclusions: Approximately one out of nine heatstroke patients developed circulatory failure during hospitalization. Circulatory failure was associated with various complications, higher mortality, and increased resource utilizations.

Acute mesenteric ischaemia in refractory shock on veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Acute mesenteric ischaemia is a severe complication in critically ill patients, but has never been evaluated in patients on veno-arterial extracorporeal membrane oxygenation (V-A ECMO). This study was designed to determine the prevalence of mesenteric ischaemia in patients supported by V-A ECMO and to evaluate its risk factors, as well as to appreciate therapeutic modalities and outcome.

METHODS

In a retrospective single centre study (January 2013 to January 2017), all consecutive adult patients who underwent V-A ECMO were included, with exclusion of those dying in the first 24 hours. Diagnosis of mesenteric ischaemia was performed using digestive endoscopy, computed tomography scan or first-line laparotomy.

RESULTS

One hundred and fifty V-A ECMOs were implanted (65 for post-cardiotomy shock, 85 for acute cardiogenic shock, including 39 patients after refractory cardiac arrest). Overall, median age was 58 (48-69) years and mortality 56%. Acute mesenteric ischaemia was suspected in 38 patients, with a delay of four (2-7) days after ECMO implantation, and confirmed in 14 patients, that is, a prevalence of 9%. Exploratory laparotomy was performed in six out of 14 patients, the others being too unstable to undergo surgery. All patients with mesenteric ischaemia died. Independent risk factors for developing mesenteric ischaemia were renal replacement therapy (odds ratio (OR) 4.5, 95% confidence interval (CI) 1.3-15.7, p=0.02) and onset of a second shock within the first five days (OR 7.8, 95% CI 1.5-41.3, p=0.02). Conversely, early initiation of enteral nutrition was negatively associated with mesenteric ischaemia (OR 0.15, 95% CI 0.03-0.69, p=0.02).

CONCLUSIONS

Acute mesenteric ischaemia is a relatively frequent but dramatic complication among patients on V-A ECMO.

Differential mechanisms of action of the trace amines octopamine, synephrine and tyramine on the porcine coronary and mesenteric artery

Trace amines such as p-tyramine, p-octopamine and p-synephrine are found in low concentrations in animals and plants. Consumption of pre-workout supplements containing these plant-derived amines has been associated with cardiovascular side effects. The aim of this study was to determine the mechanisms of action of these trace amines on porcine isolated coronary and mesenteric arteries. Noradrenaline caused contraction of mesenteric arteries and relaxation of coronary arteries. In both tissues, all three trace amines induced contractions with similar potencies and responses were unaffected by the β-adrenoceptor antagonist propranolol (1 µM), the nitric oxide synthase inhibitor L-NNA (100 µM), or the TAAR-1 antagonist, EPPTB (100 nM). However, the contractile responses of mesenteric arteries, but not coronary arteries, were significantly reduced by depletion of endogenous noradrenaline. Mesenteric responses to all three amines were abolished in the presence of prazosin (1 µM) whereas residual contractile responses remained in the coronary artery which were inhibited by a high concentration (100 µM) of EPPTB. The results suggest complex responses of the coronary artery to the trace amines, with activity at α₁-adrenoceptors and potentially TAARs other than TAAR-1. In contrast the actions of the amines on the mesenteric artery appeared to involve indirect sympathomimetic actions and direct actions on α₁-adrenoceptors.

Local gastric RAAS inhibition improves gastric microvascular perfusion in dogs

During circulatory shock, gastrointestinal microcirculation is impaired, especially via activation of the renin-angiotensin-aldosterone system. Therefore, inhibition of the renin-angiotensin-aldosterone system might be beneficial in maintaining splanchnic microcirculation. The aim of this study was to analyze whether locally applied losartan influences gastric mucosal perfusion (µflow, µvelo) and oxygenation (µHbO2) without systemic hemodynamic changes. In repetitive experiments six anesthetized dogs received 30 mg losartan topically on the oral and gastric mucosa during normovolemia and hemorrhage (-20% blood volume). Microcirculatory variables were measured with reflectance spectrometry, laser Doppler flowmetry and incident dark field imaging. Transpulmonary thermodilution and pulse contour analysis were used to measure systemic hemodynamic variables. Gastric barrier function was assessed via differential absorption of inert sugars. During normovolemia, losartan increased gastric µflow from 99 ± 6 aU to 147 ± 17 aU and µvelo from 17 ± 1 aU to 19 ± 1 aU. During hemorrhage, losartan did not improve µflow. µvelo decreased from 17 ± 1 aU to 14 ± 1 aU in the control group. Application of losartan did not significantly alter µvelo (16 ± 1 aU) compared to the control group and to baseline levels (17 ± 1 aU). No effects of topical losartan on macrohemodynamic variables or microcirculatory oxygenation were detected. Gastric microcirculatory perfusion is at least partly regulated by local angiotensin receptors. Topical application of losartan improves local perfusion via vasodilation without significant effects on systemic hemodynamics. During mild hemorrhage losartan had minor effects on regional perfusion, probably because of a pronounced upstream vasoconstriction.

Myogenic tone contributes to the regulation of permeability in mesenteric microvessels

The microvascular endothelium plays a key role in regulating solute permeability in the gut, but the contribution of vascular smooth muscle to barrier function is unknown. We sought to determine the role of vascular smooth muscle and its myogenic tone in the vascular barrier to solutes in mesenteric microvessels. We determined vascular permeability to 4.4 kDa and 70 kDa dextrans in isolated mouse mesenteric arteries at increasing pressure increments. The myogenic response was simultaneously monitored using video edge-detection of vessel diameter and wall thickness. We expressed permeability as the apparent permeability coefficient, or the solute flux per second normalized to surface area and concentration gradient. We compared the effects of myogenic tone, L-type calcium channel blockade, calcium elimination, and endothelial removal on the permeability of each dextran. We found arteries resisted changes in 4.4 kDa and 70 kDa dextran permeability coefficients at intravascular pressures associated with myogenic tone. Manipulations that reduced or eliminated myogenic tone (L-type calcium channel blockade or calcium elimination) caused vasodilation and increased permeability coefficients. Thus, the maintenance of a reactive mesenteric vascular smooth muscle layer and its myogenic tone prevents increases in vascular permeability that would otherwise occur with increasing pressure. Conditions that impact vascular tone, such as trauma, stroke, or major surgery could diminish the gut-vascular barrier against dissemination of the microbiome.

Analysis of the Effect of Intestinal Ischemia and Reperfusion on the Rat Neutrophils Proteome

Intestinal ischemia and reperfusion injury is a model system of possible consequences of severe trauma and surgery, which might result into tissue dysfunction and organ failure. Neutrophils contribute to the injuries preceded by ischemia and reperfusion. However, the mechanisms by which intestinal ischemia and reperfusion stimulate and activate circulating neutrophils is still not clear. In this work, we used proteomics approach to explore the underlying regulated mechanisms in Wistar rat neutrophils after ischemia and reperfusion. We isolated neutrophils from three different biological groups; control, sham laparotomy, and intestinal ischemia/reperfusion. In the workflow, we included iTRAQ-labeling quantification and peptide fractionation using HILIC prior to LC-MS/MS analysis. From proteomic analysis, we identified 2,045 proteins in total that were grouped into five different clusters based on their regulation trend between the experimental groups. A total of 417 proteins were found as significantly regulated in at least one of the analyzed conditions. Interestingly, the enzyme prediction analysis revealed that ischemia/reperfusion significantly reduced the relative abundance of most of the antioxidant and pro-survival molecules to cause more tissue damage and ROS production whereas some of the significantly up regulated enzymes were involved in cytoskeletal rearrangement, adhesion and migration. Clusters based KEGG pathways analysis revealed high motility, phagocytosis, directional migration, and activation of the cytoskeletal machinery in neutrophils after ischemia and reperfusion. Increased ROS production and decreased phagocytosis were experimentally validated by microscopy assays. Taken together, our findings provide a characterization of the rat neutrophil response to intestinal ischemia and reperfusion and the possible mechanisms involved in the tissue injury by neutrophils after intestinal ischemia and reperfusion.

Vasomotion of mice mesenteric arteries during low oxygen levels

Background

Ischemia of intestinal organs is a main cause of complications in surgical intensive care patients. Changes in the tonus of arteries contributing to vascular resistance play an important role in the determination of blood flow and thus oxygen supply of various abdominal organs. It is generally acknowledged that hypoxia itself is able to alter arterial tonus and thus blood flow.

Methods

The present study compared the effects of various degrees of hypoxia on second-order mesenteric arteries from male C57BL/6J mice. After vessel isolation and preparation, we assessed vessel diameter using an arteriograph perfusion chamber. Investigating mechanisms promoting hypoxia-induced vasodilatation, we performed experiments in Ca²⁺-containing and Ca²⁺-free solutions, and furthermore, Ca²⁺-influx was inhibited by NiCl₂, eNOS^−/−-, and TASK1^−/−-mice were investigated too.

Results

Mild hypoxia 14.4% O₂ induced, in 50% of mesenteric artery segments from wild-type (wt) mice, a vasodilatation; severe hypoxia recruited further segments responding with vasodilatation reaching 80% under anoxia. However, the extension of dilatation of luminal arterial diameter reduced from 1.96% ± 0.55 at 14.4% O₂ to 0.68% ± 0.13 under anoxia. Arteries exposed to hypoxia in Ca²⁺-free solution responded to lower oxygen levels with increasing degree of vasodilatation (0.85% ± 0.19 at 14.4% O₂ vs. 1.53% ± 0.42 at 2.7% O₂). Inhibition of voltage-gated Ca²⁺-influx using NiCl₂ completely diminished hypoxia-induced vasodilatation. Instead, all arterial segments investigated constricted. Furthermore, we did not observe altered hypoxia-induced vasomotion in eNOS^−/−- or TASK1^−/− mice compared to wt animals.

Conclusions

The present study demonstrated that hypoxic vasodilatation in mice mesenteric arteries is mediated by a NO-independent mechanism. In this experimental setting, we found evidence for Ca²⁺-mediated activation of ion channels causing hypoxic vasodilatation.

Electronic supplementary material

The online version of this article (10.1186/s40001-018-0335-8) contains supplementary material, which is available to authorized users.

The Pathogenesis of Nonocclusive Mesenteric Ischemia: Implications for Research and Clinical Practice

Nonocclusive mesenteric ischemia (NOMI) is a condition that can encompass ischemia, inflammation, and infarction of the intestinal wall. In contrast to most patients with acute mesenteric ischemia, NOMI is distinguished by patent arteries and veins. The clinical presentation of NOMI is often insidious and nonspecific, resulting in a delayed diagnosis. Patients most at risk are those with severe acute and critical disease, including major surgery and trauma. Nonocclusive mesenteric ischemia is part of a spectrum, from mild, asymptomatic, and an unexpected finding on CT scanning, through to those exhibiting abdominal distension and peritonitis. Severe NOMI is associated with a significant mortality rate. This review of NOMI pathophysiology was conducted to document current concepts and evidence, to examine the implications for diagnosis and treatment, and to identify gaps in knowledge that might direct future research. The key pathologic mechanisms involved in the genesis of NOMI represent an exaggerated normal physiological response to maintain perfusion of vital organs at the expense of mesenteric perfusion. A supply-demand mismatch develops in the intestine due to the development of persistent mesenteric vasoconstriction resulting in reduced blood flow and oxygen delivery to the intestine, particularly to the vulnerable superficial mucosa. This mismatch can be exacerbated by raised intra-abdominal pressure, enteral nutrition, and the use of certain vasoactive drugs, ultimately resulting in the development of intestinal ischemia. Strategies for prevention, early detection, and treatment are urgently needed.

Diagnostic accuracy of novel serological biomarkers to detect acute mesenteric ischemia: a systematic review and meta-analysis

Laparotomy remains the gold standard for diagnosis of acute mesenteric ischemia (AMI), but is often unhelpful or too late due to non-specific clinical and radiological signs. This systematic review and meta-analysis aims to evaluate the diagnostic accuracy of the novel serological biomarkers intestinal fatty acid-binding protein (I-FABP), α-glutathione S-transferase (α-GST), D-lactate, ischemia modified albumin (IMA), and citrulline to detect AMI. A systematic search of electronic databases was performed to identify all published diagnostic accuracy studies on I-FABP, α-GST, D-lactate, IMA, and citrulline. Articles were selected based on pre-defined inclusion and exclusion criteria. Risk of bias and applicability were assessed. Two-by-two contingency tables were constructed to calculate accuracy standards. Summary estimates were computed using random-effects models. The search yielded 1925 papers, 21 were included in the final analysis. Pooled sensitivity and specificity for investigated biomarkers were: I-FABP (Uden); 79.0 (95% CI 66.5-88.5) and 91.3 (87.0-94.6), I-FABP (Osaka); 75.0 (67.9-81.2) and 79.2 (76.2-82.0), D-lactate; 71.7 (58.6-82.5) and 74.2 (69.0-79.0), α-GST; 67.8 (54.2-79.5) and 84.2 (75.3-90.9), IMA; 94.7 (74.0-99.9) and 86.4 (65.1-97.1), respectively. One study investigated accuracy standards for citrulline: sensitivity 39% and specificity 100%. The novel serological biomarkers I-FABP, α-GST, IMA, and citrulline may offer improved diagnostic accuracy of acute mesenteric ischemia; however, further research is required to specify threshold values and accuracy standards for different aetiological forms.

Therapeutic Potential of Intravenous Immunoglobulin in Acute Brain Injury

Acute ischemic and traumatic injury of the central nervous system (CNS) is known to induce a cascade of inflammatory events that lead to secondary tissue damage. In particular, the sterile inflammatory response in stroke has been intensively investigated in the last decade, and numerous experimental studies demonstrated the neuroprotective potential of a targeted modulation of the immune system. Among the investigated immunomodulatory agents, intravenous immunoglobulin (IVIg) stand out due to their beneficial therapeutic potential in experimental stroke as well as several other experimental models of acute brain injuries, which are characterized by a rapidly evolving sterile inflammatory response, e.g., trauma, subarachnoid hemorrhage. IVIg are therapeutic preparations of polyclonal immunoglobulin G, extracted from the plasma of thousands of donors. In clinical practice, IVIg are the treatment of choice for diverse autoimmune diseases and various mechanisms of action have been proposed. Only recently, several experimental studies implicated a therapeutic potential of IVIg even in models of acute CNS injury, and suggested that the immune system as well as neuronal cells can directly be targeted by IVIg. This review gives further insight into the role of secondary inflammation in acute brain injury with an emphasis on stroke and investigates the therapeutic potential of IVIg.

Distribution pattern of anthropogenic marine debris along the gastrointestinal tract of green turtles (Chelonia mydas) as implications for rehabilitation

Pollution from anthropogenic marine debris (AMD) is currently the most widely distributed and lasting anthropic impact in the marine environment, affecting hundreds of species, including all sea turtles. In this study, the patterns of AMD distribution along the gastrointestinal tract (GT) and their relationship with obstructions and faecalomas in 62 green turtles (Chelonia mydas) that died during rehabilitation in southern Brazil were determined. The GT was split in seven sections, corresponding to the natural organs and intestinal areas morphologically and physiologically distinct. Mean mass (4.24g) and area (146.74cm²) of AMD in the stomach were higher than in other sections. The anterior portion of the rectum had the highest number of obstructions, followed by the stomach. AMD was associated with the obstructions, with positive correlation between faecalomas and AMD masses. Organs and subdivisions showed marked differences in susceptibility to obstructions caused by AMD, which deserves attention in clinical interventions.

Plasma biomarkers to study mechanisms of liver injury in patients with hypoxic hepatitis

BACKGROUND & AIMS

Hypoxic hepatitis is a clinical condition precipitated by prolonged periods of oxygen deprivation to the liver. It can have several underlying causes. Despite its prevalence in critically ill patients, which can reach upwards of 10%, very little is known about the mechanisms of injury. Thus, we set out to measure previously identified circulating biomarkers in an attempt to describe mechanisms of injury following hypoxic hepatitis.

METHODS

Plasma from patients diagnosed with hypoxic hepatitis was collected for this study. Biomarkers of hepatocellular injury, mitochondrial damage and cell death were measured. These results were compared against results obtained from well-characterized acetaminophen overdose patients.

RESULTS

At peak injury, ALT measured 4082±606 U/L and gradually decreased over 5 days, corresponding to the clinically observed pattern of hypoxic hepatitis. Levels of GDH showed a similar pattern, but neither ALT nor GDH were significantly higher in these patients than in acetaminophen patients. Plasma levels of DNA fragments mimicked hepatocellular injury as measured by ALT and miRNA-122. Interestingly, we found a significant increase in caspase-cleaved cytokeratin-18; however, the full-length form greatly exceeded the cleaved form at the time of maximum injury (45837±12085 vs 2528±1074 U/L). We also found an increase in acHMGB1 at later time points indicating a possible role of inflammation, but cytokine levels at these times were actually decreased relative to early time points.

CONCLUSIONS

The mechanism of injury following hypoxic hepatitis involves mitochondrial damage and DNA fragmentation. Importantly, necrosis, rather than apoptosis, is the main mode of cell death.

Acute transfusion-related abdominal injury in trauma patients: a case report

Background

Secondary abdominal compartment syndrome is well known as a life-threatening complication in critically ill patients in an intensive care unit. Massive crystalloid fluid resuscitation has been identified as the most important risk factor. The time interval from hospital admittance to the development of manifest abdominal compartment syndrome is usually greater than 24 hours. In the absence of any direct abdominal trauma, we observed a rapidly evolving secondary abdominal compartment syndrome shortly after hospital admittance associated with massive transfusion of blood products and only moderate crystalloid resuscitation.

Case presentation

We report the case of an acute secondary abdominal compartment syndrome developing within 3 to 4 hours in a 74-year-old polytraumatized white woman. Although multiple fractures of her extremities and a B-type pelvic ring fracture were diagnosed by a full body computed tomography scan, no intra-abdominal injury could be detected. Hemorrhagic shock with a drop in her hemoglobin level to 5.7 g/dl was treated by massive transfusion of blood products and high doses of catecholamines. Shortly afterwards, her pulmonary gas exchange progressively deteriorated and mechanical ventilation became almost impossible with peak airway pressures of up to 60 cmH₂O. Her abdomen appeared rigid and tense accompanied by a progressive hemodynamic decompensation necessitating mechanic cardiopulmonary resuscitation. Although preoperative computed tomography scans showed no signs of intra-abdominal fluid, a decompressive laparotomy under cardiopulmonary resuscitation conditions was performed and 2 liters of ascites-like fluid disgorged. Her hemodynamics and pulmonary ventilation improved immediately.

Conclusions

This case report describes for the first time acute secondary abdominal compartment syndrome in a trauma patient, evolving in a very short time period. We hypothesize that the massive transfusion of blood products along with high doses of catecholamines triggered the acute development of abdominal compartment syndrome. Trauma teams need to consider a rapidly developing secondary abdominal compartment syndrome to be a potential cause of hemodynamic decompensation not only in the later phase of treatment but also in the emergency phase of treatment.

Shock Induction by Arterial Hypoperfusion of the Gut Involves Synergistic Interactions between the Peripheral Enkephalin and Nitric Oxide Systems

To determine whether critical splanchnic artery hypoperfusion can provoke systemic shock and to identify the roles of the peripheral opioid and nitric oxide (NO) systems in this process, various degrees of superior mesenteric artery hypoperfusion (SMA-H) were produced in anesthetized adult rabbits (n=40), and hemodynamic and metabolic indices were measured. Metabolic acidosis and irreversible hypodynamic shock occurred with SMA-H at levels representing 25–20% of mean baseline SMA blood flow. In 112 other rabbits subjected to SMA-H at 20% (SMA-H20%), we studied plasma NO and enkephalin (ENK) levels, cardiovascular reactivity to selected physiological agonists, effects of ENKs on plasma NO levels, and effects of peripheral opioid receptor blockade and inducible NO synthase (iNOS) inhibition. SMA-H20% progressively increased systemic blood levels of NO and ENKs. Exogenous ENK administration accentuated SMA-H20%-induced increases in plasma NO levels, and their cardiovascular depressing effects were significantly greater when they were administered during SMA-H20% (vs. administration under baseline conditions). Selective blockade of cardiovascular δ-opioid receptors improved hemodynamics, prevented shock irreversibility and reduced plasma NO levels; similar effects were obtained by selective iNOS inhibition. These findings demonstrate that critical arterial hypoperfusion of the gut can induce hypodynamic systemic shock through ENK-induced hyperactivation of cardiovascular δ-opioid receptors, which leads to increased plasma levels of NO related in part to increased iNOS activity. Since pronounced splanchnic artery hypoperfusion occurs in all advanced systemic shock states, selective δ-opioid receptor antagonists and/or iNOS inhibitors may prove to be useful in improving shock hemodynamics and metabolic derangements and/or preventing progression toward irreversibility.

Indications, techniques, and clinical outcomes of thoracic duct interventions in patients: a forgotten literature?

BACKGROUND

The evolution of the "gut-lymph concept" has promoted thoracic duct (TD) lymph drainage as a possible treatment to reduce systemic inflammation and end-organ dysfunction in acute illness. The aim was to review the published experience of thoracic duct interventions (TDIs) aimed at improving clinical outcomes.

METHODS

A search of three databases (MEDLINE, EMBASE, and EMBASE CLASSIC) over the last 60 y. The indications for intervention, the technique, and clinical outcomes were reviewed.

RESULTS

There were a wide range of indications for TDI. These included reducing rejection after transplantation, treating inflammatory diseases, and reducing chronic failure of the liver, kidney, and heart. The techniques included TD cannulation and lymphovenuous fistula. The outcomes were variable and often equivocal, and this appears to reflect poor design quality. There is clinical equipoise regarding a therapeutic role of (TD lymph drainage in acute pancreatitis, and probably other acute diseases.

CONCLUSIONS

Until well-designed clinical trials are undertaken, the clinical benefits of TDIs will remain promising, but uncertain.

Influence of thoracic epidural anesthesia on gastric oxygenation during hypothermia and hemorrhage

OBJECTIVE

Hypothermia preserves gastric mucosal microvascular oxygenation (μHbO2) during hemorrhagic shock. Additionally, hypothermia activates the sympathetic nervous system that leads to the release of vasopressin. The aim of this study was to evaluate whether the effect of hypothermia is mediated via the sympathetic nervous system and/or via vasopressin.

METHODS

In prospective and randomized experiments on five anesthetized dogs (foxhounds, cross-over design, 6 groups with n=5 per group) we analyzed the effects of hemorrhage on μHbO2 during mild hypothermia (HT, 34 °C), during additional thoracic epidural anesthesia (HT/TEA) and during additional vasopressin V1 receptor blockade (HT/VB). As control groups, effects of hemorrhage were studied under normothermia alone (NT), during additional thoracic epidural anesthesia (NT/TEA) and during additional vasopressin V1 receptor blockade (NT/VB).

RESULTS

Hemorrhage decreased μHbO2 from 81 ± 3 to 49 ± 8%. In contrast, in the presence of hypothermia, μHbO2 was significantly higher during hemorrhagic shock (from 79 ± 3 to 66 ± 9%) despite a similar decrease in DO2. The effect of hypothermia on μHbO2 was reduced in the presence of thoracic epidural anesthesia or vasopressin receptor blockade.

CONCLUSIONS

Hypothermia preserves μHbO2 during hemorrhagic shock. This effect is partially abolished during thoracic epidural anesthesia or during vasopressin receptor blockade. The sympathetic nervous system and the vasopressin V1 receptor are partially involved in mediating the effect of hypothermia on gastric oxygenation during hemorrhage.

A snapshot of circulation failure following acute traumatic injury: The expansion of computed tomography beyond injury diagnosis

OBJECTIVE

CT scans with a flat Inferior Vena Cava (IVC) suggest hypovolemia, and the presence of shock bowel implies hypoperfusion. The purpose of this study is to correlate injury severity, resuscitation needs, and clinical outcomes with CT indices of hypovolemia and hypoperfusion.

DESIGN

Retrospective cohort study.

SETTING

Level II trauma centre in Central California.

PATIENTS

Adult patients imaged with abdominal and pelvic CT scans, from January 2010-January 2011.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Circulatory derangements on CT scans were defined as an IVC (AP) diameter measurement of <9 mm, flat IVC (FIVC), hypovolemia. The presence of small intestine hypoperfusion was shock bowel (SB). The absence of these findings was a normal CT scan (NCT). Comparisons of acid-base status, fluids, morbidity and mortality were made based on CT findings. Subgroups were: FIVC (n=20), FIVC+SB (n=19), SB (n=4) only versus normal CT scans, NCT (n=47).

RESULTS

Overall ISS was 19 (SD) 14. The lowest ISS was in NCT 14 (SD) 10 and there was an incremental increase in ISS based on circulatory derangements, p=0.001. ICU admission was lowest in NCT and highest in the presence of hyovolemia and hypoperfusion, p=0.03. Similarly ED crystalloid requirements and the activation of a massive transfusion protocol (MTP), was lowest in NCT group and gradually increased significantly as hypovolemia and hypoperfusion was demonstrated on CT scans. Additional parameters such as metabolic acidosis, nosocomial infections and mortality were associated with acute CT findings of circulatory failure.

CONCLUSIONS

Hypovolemia and hypoperfusion, markers of abnormal circulation, were demonstrated on CT scans for trauma evaluation. The presence of these findings alone or in combination showed strong correlation with high injury severity, and the need for aggressive resuscitation.

Effects of different types of fluid resuscitation for hemorrhagic shock on splanchnic organ microcirculation and renal reactive oxygen species formation

INTRODUCTION

Fluid resuscitation is an indispensable procedure in the acute management of hemorrhagic shock for restoring tissue perfusion, particularly microcirculation in splanchnic organs. Resuscitation fluids include crystalloids, hypertonic saline (HTS), and synthetic colloids, and their selection affects the recovery of microcirculatory blood flow and reactive oxygen species (ROS) formation, which is often evident in the kidney, following reperfusion. In this study, the effects of acute resuscitation with 0.9% saline (NS), 3% HTS, 4% succinylated gelatin (GEL), and 6% hydroxyethyl starch (HES) 130/0.4 were compared in a hemorrhagic shock rat model to analyze restoration of microcirculation among various splanchnic organs and the gracilis muscle and reperfusion-induced renal ROS formation.

METHODS

A total of 96 male Wistar rats were subjected to sham operation (sham group), hemorrhagic shock (control group), and resuscitation with NS, HTS, GEL and HES. Two hours after resuscitation, changes in the mean arterial pressure (MAP), serum lactate level and the microcirculatory blood flow among various splanchnic organs, namely the liver, kidney, and intestine (mucosa, serosal muscular layer, and Peyer's patch), and the gracilis muscle, were compared using laser speckle contrast imaging. Renal ROS formation after reperfusion was investigated using an enhanced in vivo chemiluminescence (CL) method.

RESULTS

Microcirculatory blood flow was less severely affected by hemorrhaging in the liver and gracilis muscle. Impairment of microcirculation in the kidney was restored in all resuscitation groups. Resuscitation in the NS group failed to restore intestinal microcirculation. Resuscitation in the HTS, GEL, and HES groups restored intestinal microcirculatory blood flow. By comparison, fluid resuscitation restored hemorrhagic shock-induced hypotension and decreased lactatemia in all resuscitation groups. Reperfusion-induced in vivo renal ROS formation was significantly higher in the GEL and HES groups than in the other groups.

CONCLUSION

Although fluid resuscitation with NS restored the MAP and decreased lactatemia following hemorrhagic shock, intestinal microcirculation was restored only by other volume expanders, namely 3% HTS, GEL, and HES. However, reperfusion-induced renal ROS formation was significantly higher when synthetic colloids were used.

Intraluminal nonbacterial intestinal components control gut and lung injury after trauma hemorrhagic shock

OBJECTIVE

To test whether the mucus layer, luminal digestive enzymes, and intestinal mast cells are critical components in the pathogenesis of trauma shock-induced gut and lung injury.

BACKGROUND

Gut origin sepsis studies have highlighted the importance of the systemic component (ischemia-reperfusion) of gut injury, whereas the intraluminal component is less well studied.

METHODS

In rats subjected to trauma hemorrhagic shock (T/HS) or sham shock, the role of pancreatic enzymes in gut injury was tested by diversion of pancreatic enzymes via pancreatic duct exteriorization whereas the role of the mucus layer was tested via the enteral administration of a mucus surrogate. In addition, the role of mast cells was assessed by measuring mast cell activation and the ability of pharmacologic inhibition of mast cells to abrogate gut and lung injury. Gut and mucus injury was characterized functionally, morphologically, and chemically.

RESULTS

Pancreatic duct exteriorization abrogated T/HS-induced gut barrier loss and limited chemical mucus changes. The mucus surrogate prevented T/HS-induced gut and lung injury. Finally, pancreatic enzyme-induced gut and lung injury seems to involve mast cell activation because T/HS activates mast cells and pharmacologic inhibition of intestinal mast cells prevented T/HS-induced gut and lung injury.

CONCLUSIONS

These results indicate that gut and gut-induced lung injury after T/HS involves a complex process consisting of intraluminal digestive enzymes, the unstirred mucus layer, and a systemic ischemic-reperfusion injury. This suggests the possibility of intraluminal therapeutic strategies.

Evaluation of the effects of ischemic preconditioning on the hematological parameters of rats subjected to intestinal ischemia and reperfusion

OBJECTIVES

Intestinal ischemia/reperfusion often leads to acute lung injury and multiple organ failure. Ischemic preconditioning is protective in nature and reduces tissue injuries in animal and human models. Although hematimetric parameters are widely used as diagnostic tools, there is no report of the influence of intestinal ischemia/reperfusion and ischemic preconditioning on such parameters. We evaluated the hematological changes during ischemia/reperfusion and preconditioning in rats.

METHODS

Forty healthy rats were divided into four groups: control, laparotomy, intestinal ischemia/reperfusion and ischemic preconditioning. The intestinal ischemia/reperfusion group received 45 min of superior mesenteric artery occlusion, while the ischemic preconditioning group received 10 min of short ischemia and reperfusion before 45 min of prolonged occlusion. A cell counter was used to analyze blood obtained from rats before and after the surgical procedures and the hematological results were compared among the groups.

RESULTS

The results showed significant differences in hematimetric parameters among the groups. The parameters that showed significant differences included lymphocyte, white blood cells and granulocyte counts; hematocrit; mean corpuscular hemoglobin concentration; red cell deviation width; platelet count; mean platelet volume; plateletcrit and platelet distribution width.

CONCLUSION

The most remarkable parameters were those related to leukocytes and platelets. Some of the data, including the lymphocyte and granulocytes counts, suggest that ischemic preconditioning attenuates the effect of intestinal ischemia/reperfusion on circulating blood cells. Our work contributes to a better understanding of the hematological responses after intestinal ischemia/reperfusion and IPC, and the present findings may also be used as predictive values.

Antioxidant and anti-inflammatory effects of selenium in oral buccal mucosa and small intestinal mucosa during intestinal ischemia-reperfusion injury

Background

The aim of this study were to investigate whether selenium treatment attenuates lipid peroxidation and downregulates the NF-κB pathway in small intestinal mucosa and to examine whether the effect of selenium is also observed in oral buccal mucosa, during small intestinal IR injury.

Materials and methods

Eighteen rats were assigned into three groups: sham, IR, and IR + selenium. Saline or selenium was administered through a tail vein. 24 hours later, the superior mesenteric artery was exposed and clamped in the IR and IR + selenium groups. After ischemic and reperfusion period, animals were sacrificed and oral buccal mucosa and small intestinal mucosa were harvested.

Results

Glutathione peroxidase activity and cytoplasmic IκB-α expression was higher in the IR + selenium group than that in the IR group. A malondialdehyde level, cytoplasmic phosphorylated inhibitor κB-α, nuclear NF-κB p65 expressions, and NF-κB p65 DNA-binding activity were lower in the IR + selenium group than those in the IR group.

Conclusion

A selenium treatment may cause increased GPx activity, attenuated lipid peroxidation, and downregulated the NF-κB pathway during small intestinal IR injury. Furthermore, these therapeutic benefits of selenium can be observed in oral buccal mucosa as well as small intestinal mucosa.

Pentoxifylline attenuates leukocyte-endothelial interactions in a two-hit model of shock and sepsis

BACKGROUND

This study investigated the effects of pentoxifylline (PTX) combined with resuscitation fluids on microcirculatory dysfunctions in a two-hit model of shock and sepsis.

MATERIALS AND METHODS

Male Wistar rats (250 g) were submitted to hemorrhagic shock and reperfusion followed by sepsis induced by cecal ligation and puncture. For the initial treatment of shock, rats were randomly divided into: sham, no injury, no treatment; hypertonic saline solution (HS) (7.5%, 4 mL/kg); lactated Ringer's solution (LR, 3 × shed blood volume); HS + PTX (4 mL/Kg + 25 mg/kg PTX); and LR + PTX (3 × shed blood volume + 25 mg/kg PTX). After 48 h of being exposed to the double injury, leukocyte-endothelial interactions were assessed by intravital microscopy of the mesentery. Endothelial expression of P-selectin and intercellular adhesion molecule-1 (ICAM-1) was evaluated by immunohistochemistry, as well as lung neutrophil infiltration by histology.

RESULTS

Lactated Ringer's solution induced marked increases (P < 0.001) in the number of rolling leukocytes per 10 min (two-fold), adherent leukocytes per 100 μm venule length (six-fold), migrated leukocytes per 5000 μm(2) (eight-fold), P-selectin and ICAM-1 expression (four-fold), and lung neutrophil infiltration (three-fold) compared with sham. In contrast, PTX attenuated leukocyte-endothelial interactions, P-selectin and ICAM-1 expression at the mesentery when associated with either LR (P < 0.001) or HS (P < 0.05). Neutrophil migration into the lungs was similarly reduced by PTX (P < 0.05).

CONCLUSIONS

Data presented showed that pentoxifylline attenuates microcirculatory disturbances at the mesenteric bed with significant minimization of lung inflammation after a double-injury model of hemorrhagic shock and reperfusion followed by sepsis.

Enteral nutrition in the hemodynamically unstable critically ill patient

The benefit of enteral nutrition in critically ill patients has been demonstrated by several studies, especially when it is started early, in the first 24-48h of stay in the Intensive Care Unit, and this practice is currently advised by the main clinical guidelines. The start of enteral nutrition is controversial in patients with hemodynamic failure, since it may trigger intestinal ischemia. However, there are data from experimental studies in animals, as well as from observational studies in humans that allow for hypotheses regarding its beneficial effect and safety. Interventional clinical trials are needed to confirm these findings.

Role of hydroxyethyl starch in ischemia-reperfusion injury in rat intestinal transplantation

OBJECTIVE

This study was designed to evaluate the role of 0%, 3%, 6% hydroxyethyl starch (HES) and University of Wisconsin (UW) perfusion and preservation solutions on ischemia-reperfusion injury (IRI) of rat intestinal transplantations, solutions, respectively.

MATERIALS AND METHODS

Rats underwent orthotopic intestinal transplantation (Lewis to Lewis) after using perfusion and preservation saline (group l), 3% HES (group 2), 6% HES (group 3), or UW (group 4) solutions. The change in weight was recorded from preoperative to postoperative day (POD) 30. At 30 minutes after reperfusion, we harvested intestinal juice preoperatively as well as at 30 minutes after reperfusion and on POD 1 and 3 when recipients underwent open surgery for maltose absorption tests and sampling. The Park' scores of IRI were evaluated by light microscopy after hematoxylin and eosin (H&E) staining.

RESULTS

An increased weight was more evident in group 2 than the other groups, particularly the on POD 1 and POD 3 (P < .05). It was significantly greater than groups 1 and 3 on POD 7 (P < .05). Compared with the other groups, the 30-minute post-reperfusion. Park score and intestinal juice content in group 2 was decreased significantly (P < .01), while in group 3 the Park score was increased, and the maltose absorption level decreased significantly (P < .05).

CONCLUSION

Three percent HES solution attenuated IRI in rat intestinal transplantation. High-concentration HES solutions were unfit for intestinal preservation. Thus the adverse effects of UW solution may be attribute at least in part to its high HES, concentration.

Near-infrared spectroscopy: exposing the dark (venous) side of the circulation

The safety of anesthesia has improved greatly in the past three decades. Standard perioperative monitoring, including pulse oximetry, has practically eliminated unrecognized arterial hypoxia as a cause for perioperative injury. However, most anesthesia-related cardiac arrests in children are now cardiovascular in origin, and standard monitoring is unable to detect many circulatory abnormalities. Near-infrared spectroscopy provides noninvasive continuous access to the venous side of regional circulations that can approximate organ-specific and global measures to facilitate the detection of circulatory abnormalities and drive goal-directed interventions to reduce end-organ ischemic injury.

Impaired effect of relaxin on vasoconstrictor reactivity in spontaneous hypertensive rats

Relaxin is thought to be involved in vasodilation to pregnancy by increasing endothelium-dependent vasodilation and compliance, and decreasing myogenic reactivity. Primary (essential) hypertension predisposes to circulatory maladaptation and subsequent gestational hypertensive disease. This study aimed to determine that vascular responses to chronic exposure to relaxin are impaired in young female rats with primary hypertension. In 10-12 weeks old Wistar-Hannover rats (WHR) and spontaneous hypertensive rats (SHR), we determined vascular responses in isolated kidney and mesenteric arteries after 5-days of chronic exposure to relaxin (4 μg/h) or placebo. SHR show decreased sensitivity to phenylephrine (by 67%, p<0.01) and renal perfusion flow (RPFF, by 19%, p<0.01), but no changes in flow-mediated vasodilation, myogenic reactivity or vascular compliance. In WHR, relaxin stimulated flow-mediated vasodilation (2.67 fold, from 48 ± 9 to 18 ± 4 μl/min, p = 0.001), inhibited myogenic reactivity (from -1 ± 2 to 7 ± 3 μm/10 mmHg, p = 0.01), and decreased sensitivity to phenylephrine (28%, from 1.39 ± 0.08 to 1.78 ± 0.10 μM, p<0.01), but left compliance and RPFF unchanged. NO-blockade by L-NAME diminished most relaxin-mediated responses. In SHR, the vasodilator effects of relaxin were blunted for myogenic reactivity and sensitivity to phenylephrine, with similar effects on flow-mediated vasodilation, compliance, RPFF and equal Rxfp1 (relaxin family peptide receptor) gene expression, as compared to WHR. Primary hypertension blunts both the relaxin-induced inhibition of myogenic reactivity and α-adrenergic vasoconstrictor response, independent from Rxfp1 gene expression, while the relaxin-dependent enhanced flow-mediated vasodilation remains intact. This implies selective resistance to relaxin in young subjects suffering from primary hypertension.

Effect of dexmedetomidine pretreatment on lung injury following intestinal ischemia-reperfusion

Reperfusion injury is tissue damage caused by the re-supply of blood following a period of ischemia in tissues. Intestinal ischemia-reperfusion injury (IRI) is an extremely common clinical event associated with distant organ injury. The intestine serves as the initial organ of multi-system organ dysfunction syndrome. It is extremely important to identify a method to protect against IRI, as it is a key factor associated with morbidity and mortality in patients. In the present study, the protective effects of pretreatment with dexmedetomidine hydrochloride were investigated. Rats were divided into six groups and models of intestinal ischemia were created in the five groups. Certain groups were pretreated with dexmedetomidine hydrochloride. The levels of TNF-α and IL-6 were measured by enzyme-linked immunosorbent assay in order to evaluate the injury. Tissue sections were stained with hematoxylin and eosin to visualize the damage. qPCR and western blotting were performed to examine the inflammatory status. Pretreatment with various doses of dexmedetomidine hydrochloride significantly reduced the pathological scores and the inflammatory reaction. The levels of TNF-α, IL-6, TLR4 and MyD88 were decreased in the dexmedetomidine hydrochloride treatment groups compared with those in the sham control and untreated ischemia reperfusion groups. The results of the present study indicate that pretreatment with dexmedetomidine hydrochloride may be a useful method of reducing the damage caused by IRI.