Understanding gastrointestinal perfusion in critical care: so near, and yet so far

Incidence of Acute Upper Gastrointestinal Bleeding and Related Risk Factors among Elderly Patients Undergoing Surgery for Major Limb Fractures: An Analytical Cohort Study

(1) Background: Upper gastrointestinal bleeding (UGIB), a major postoperative complication after surgical fixation of major limb fractures, can be fatal but is often neglected. This study determined the incidence rates of and related risk factors for perioperative UGIB among older patients with major upper limb fractures but without a history of peptic ulcer disease (PUD). (2) Methods: We collected the data of patients aged more than 65 years who underwent surgery for major limb fracture between 1 January 2001 and 31 December 2017, from Taiwan's National Health Insurance Research Database and excluded those with a history of UGIB and PUD before the date of surgery. The primary outcome was the incidence of UGIB requiring panendoscopy during hospitalization. A multiple logistic regression model was used to identify the independent predictors of UGIB, with adjustment for confounding factors. The final model included variables that were either statistically significant in univariate analyses or deemed clinically important. (3) Results: The incidence of UGIB was 2.8% among patients with major limb fractures. Male sex, older age, major lower limb fracture, and a history of chronic renal disease were significant risk factors for the increased incidence of perioperative UGIB. (4) Conclusions: Patients with major limb fractures who underwent surgery exhibited a higher rate of stress ulceration with UGIB, even when they had no history of PUD. Perioperative preventive protocols (e.g., protocols for the administration of proton-pump inhibitors) may be necessary for patients with these major risk factors.

Gut barrier protein levels in serial blood samples from critically ill trauma patients during and after intensive care unit stay

PURPOSE

In an effort to better manage critically ill patients hospitalised in the intensive care unit (ICU) after experiencing multiple traumas, the present study aimed to assess whether plasma levels of intestinal epithelial cell barrier proteins, including occludin, claudin-1, junctional adhesion molecule (JAM-1), tricellulin and zonulin, could be used as novel biomarkers. Additional potential markers such as intestinal fatty acid-binding protein (I-FABP), D-lactate, lipopolysaccharide (LPS) and citrulline were also evaluated. We also aimed to determine the possible relationships between the clinical, laboratory, and nutritional status of patients and the measured marker levels.

METHODS

Plasma samples from 29 patients (first, second, fifth and tenth days in the ICU and on days 7, 30 and 60 after hospital discharge) and 23 controls were subjected to commercial enzyme-linked immunosorbent assay (ELISA) testing.

RESULTS

On first day (admission) and on the second day, plasma I-FABP, D-lactate, citrulline, occludin, claudin-1, tricellulin and zonulin levels were high in trauma patients and positively correlated with lactate, C-reactive protein (CRP), number of days of ICU hospitalisation, Acute Physiology and Chronic Health Evaluation II (APACHE II) score and daily Sequential Organ Failure Assessment (SOFA) scores (P < 0.05-P < 0.01).

CONCLUSION

The results of the present study showed that occludin, claudin-1, tricellulin and zonulin proteins, as well as I-FABP, D-lactate and citrulline, may be used as promising biomarkers for the evaluation of disease severity in critically ill trauma patients, despite the complexity of the analysis of various barrier markers. However, our results should be supported by future studies.

The leaky gut and the gut microbiome in sepsis - targets in research and treatment

Both a leaky gut (a barrier defect of the intestinal surface) and gut dysbiosis (a change in the intestinal microbial population) are intrinsic to sepsis. While sepsis itself can cause dysbiosis, dysbiosis can worsen sepsis. The leaky gut syndrome refers to a status with which there is an increased intestinal permeability allowing the translocation of microbial molecules from the gut into the blood circulation. It is not just a symptom of gastrointestinal involvement, but also an underlying cause that develops independently, and its presence could be recognized by the detection, in blood, of lipopolysaccharides and (1→3)-β-D-glucan (major components of gut microbiota). Gut-dysbiosis is the consequence of a reduction in some bacterial species in the gut microbiome, as a consequence of intestinal mucosal immunity defect, caused by intestinal hypoperfusion, immune cell apoptosis, and a variety of enteric neuro-humoral-immunity responses. A reduction in bacteria that produce short-chain fatty acids could change the intestinal barriers, leading to the translocation of pathogen molecules, into the circulation where it causes systemic inflammation. Even gut fungi might be increased in human patients with sepsis, even though this has not been consistently observed in murine models of sepsis, probably because of the longer duration of sepsis and also antibiotic use in patients. The gut virobiome that partly consists of bacteriophages is also detectable in gut contents that might be different between sepsis and normal hosts. These alterations of gut dysbiosis altogether could be an interesting target for sepsis adjuvant therapies, e.g., by faecal transplantation or probiotic therapy. Here, current information on leaky gut and gut dysbiosis along with the potential biomarkers, new treatment strategies, and future research topics are mentioned.

R, Patel PH, Bazan DZ, Mora A, Samuel N, Mingle AC, Leon LR, Varon J, Surani S. Drug-Induced Hyperthermia Review

Humans maintain core body temperature via a complicated system of physiologic mechanisms that counteract heat/cold fluctuations from metabolism, exertion, and the environment. Overextension of these mechanisms or disruption of body temperature homeostasis leads to bodily dysfunction, culminating in a syndrome analogous to exertional heat stroke (EHS). The inability of this thermoregulatory process to maintain the body temperature is caused by either thermal stress or certain drugs. EHS is a syndrome characterized by hyperthermia and the activation of systemic inflammation. Several drug-induced hyperthermic syndromes may resemble EHS and share common mechanisms. The purpose of this article is to review the current literature and compare exertional heat stroke (EHS) to three of the most widely studied drug-induced hyperthermic syndromes: malignant hyperthermia (MH), neuroleptic malignant syndrome (NMS), and serotonin syndrome (SS). Drugs and drug classes that have been implicated in these conditions include amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and many more. Observations suggest that severe or fulminant cases of drug-induced hyperthermia may evolve into an inflammatory syndrome best described as heat stroke. Their underlying mechanisms, symptoms, and treatment approaches will be reviewed to assist in accurate diagnosis, which will impact the management of potentially life-threatening complications.

Acute gastrointestinal injury in critically ill children: Impact on clinical outcome

AIM

To estimate acute gastrointestinal injury (AGI) in critically ill children and association of its severity with mortality.

METHODS

In a prospective cohort study, critically ill children (1 month-18 years) were enrolled. Gastrointestinal symptoms over the first week of admission were classified into AGI grades 1 through 4, using a paediatric adaptation of European Society of Intensive Care Medicine AGI definitions. Performance of AGI grades in predicting 28-day mortality was evaluated.

RESULTS

Of 151 children enrolled, 71 (47%, 95% confidence interval (CI): 38.9-55.3%) developed AGI, with AGI grades 1, 2, 3 and 4 in 22.5%, 15.9%, 6.6% and 2%, respectively. The 28-day mortality progressively increased with AGI grade 0 (15%), 1 (35%), 2 (50%), 3 (70%), through 4 (100%), P < 0.001. Association of AGI grades with 28-day mortality was significant even after adjustment for disease severity, age and nutritional status (odds ratio (OR) = 2.152, 95% CI: 1.455, 3.184). Among AGI grades, and paediatric logistic organ dysfunction-2 score components, cardiovascular (OR = 1.525, 95% CI: 1.142, 2.037) and haematological (OR = 1.719, 95% CI: 1.067, 2.772) components of paediatric logistic organ dysfunction-2 score and AGI grades (OR = 1.565, 95% CI: 1.001, 2.449) showed significant association with 28-day mortality.

CONCLUSIONS

Nearly half of the critically ill children developed AGI. AGI grades were independently associated with increased mortality, and mortality progressively increased with AGI grade.

Enteral feeding, even when the gut does not feel very good?

PURPOSE OF REVIEW

To summarize knowledge on the gut function in relation to enteral nutrition.

RECENT FINDINGS

The gut is certainly suffering during critical illness but our understanding of the exact mechanisms involved is limited. Physicians at bedside are lacking tools to identify how well or bad the gut is doing and whether the gut is responding adequately to critical illness. Sensing nutrition as a signal is important for the gut and microbiome. Enteral nutrition has beneficial effects for the gut perfusion and function. However, early full enteral nutrition in patients with shock was associated with an increased number of rare but serious complications.

SUMMARY

Whenever synthesizing knowledge in physiology and available evidence in critically ill, we suggest that enteral nutrition has beneficial effects but may turn harmful if provided too aggressively. Contraindications to enteral nutrition are listed in recent guidelines. For patients with gastrointestinal dysfunction but without these contraindications, we suggest considering early enteral nutrition as a signal to the gut and to the body rather than an energy and protein provision. With this rationale, we think that low dose of enteral nutrition could and probably should be provided also when the gut does not feel very good. Understanding the feedback from the gut in response to enteral nutrition would be important, however, monitoring tools are currently limited to clinical assessment only.

Should we routinely prescribe proton pump inhibitors peri-operatively in elderly patients with hip fractures? A review of the literature

Elderly hip fracture patients are at risk of stress-related gastric mucosal damage, and upper gastrointestinal bleeding is one of the underrecognized but devastating complications.

Proton pump inhibitors (PPIs) offer effective prophylaxis against stress-related gastric mucosal damage.

Systematic analysis of the literature revealed numerous articles on PPIs and hip fractures, but only three articles dedicated to the analysis of prophylactic use of PPIs in patients with a hip fracture.

There is significant reduction in upper gastrointestinal bleeding following PPI prophylaxis and reduced 90-day mortality in elderly hip fracture patients on prophylaxis.

PPIs are generally safe, cost-effective and based on available evidence. Their prophylactic use is justifiable in elderly patients with hip fractures.

We suggest that PPIs be prescribed routinely peri-operatively in elderly hip fracture patients. Further level-one studies on the subject will allow for firmer recommendations.

Cite this article: EFORT Open Rev 2021;6:686-691. DOI: 10.1302/2058-5241.6.200053

A Clinician's Guide to Dosing Analgesics, Anticonvulsants, and Psychotropic Medications in Continuous Renal Replacement Therapy

Acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT) is a common complication in critical illness and has a significant impact on pharmacokinetic factors determining drug exposure, including absorption, distribution, transport, metabolism, and clearance. In this review, we provide a practical guide to drug dosing considerations in critically ill patients undergoing CRRT, focusing on the most commonly used analgesic, anticonvulsant, and psychotropic medications in the clinical care of critically ill patients. A literature search was conducted to identify articles in which drug dosing was evaluated in adult patients receiving CRRT between the years 1980 and 2020. We included articles with pharmacokinetic/pharmacodynamic analyses and those that described medication clearance via CRRT. A summary of the data focused on practical pharmacokinetic and pharmacodynamic principles is presented, with recommendations for drug dosing of analgesics, anticonvulsants, and psychotropic medications. Pharmacokinetic and pharmacodynamic studies to guide drug dosing of analgesics, anticonvulsants, and psychotropic medications in critically ill patients receiving CRRT are sparse. Considering the widespread use of these medications, narrow therapeutic index of these drug classes, and risks of over- and underdosing, additional studies in patients receiving CRRT are needed to inform drug dosing.

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.

Exogenous vasopressin dose-dependently modulates gastric microcirculatory oxygenation in dogs via V1A receptor

BACKGROUND

Hypercapnia improves gastric microcirculatory oxygenation (μHbO₂) and increases vasopressin plasma levels, whereas V1A receptor blockade abolishes the increase of μHbO₂. The aim of this study was to evaluate the effect of exogenous vasopressin (AVP) in increasing doses on microcirculatory perfusion and oxygenation and systemic hemodynamic variables. Furthermore, we evaluated the role of the vasopressin V1A receptor in mediating the effects.

METHODS

In repetitive experiments, six anesthetized dogs received a selective vasopressin V1A receptor inhibitor ([Pmp¹, Tyr (Me)²]-Arg⁸-Vasopressin) or sodium chloride (control groups). Thereafter, a continuous infusion of AVP was started with dose escalation every 30 min (0.001 ng/kg/min-1 ng/kg/min). Microcirculatory variables of the oral and gastric mucosa were measured with reflectance spectrometry, laser Doppler flowmetry, and incident dark field imaging. Transpulmonary thermodilution was used to measure systemic hemodynamic variables. AVP plasma concentrations were measured during baseline conditions and 30 min after each dose escalation.

RESULTS

During control conditions, gastric μHbO₂ did not change during the course of experiments. Infusion of 0.001 ng/kg/min and 0.01 ng/kg/min AVP increased gastric μHbO₂ to 87 ± 4% and 87 ± 6%, respectively, compared to baseline values (80 ± 7%), whereas application of 1 ng/kg/min AVP strongly reduced gastric μHbO₂ (59 ± 16%). V1A receptor blockade prior to AVP treatment abolished these effects on μHbO₂. AVP dose-dependently enhanced systemic vascular resistance (SVR) and decreased cardiac output (CO). After prior V1A receptor blockade, SVR was reduced and CO increased (0.1 ng/kg/min + 1 ng/kg/min AVP).

CONCLUSIONS

Exogenous AVP dose-dependently modulates gastric μHbO₂, with an increased μHbO₂ with ultra-low dose AVP. The effects of AVP on μHbO₂ are abolished by V1A receptor inhibition. These effects are independent of a modulation of systemic hemodynamic variables.

Fulminant Necrotizing Enterocolitis and Multiple Organ Dysfunction in a Toddler with Mitochondrial DNA Depletion Syndrome-13

Necrotizing enterocolitis (NEC) is exceptional after the neonatal period. A toddler with encephalopathy, mitochondrial myopathy, and hypertrophic cardiomyopathy developed fatal NEC and multiple organ dysfunction within 48 hours of the introduction of enteral feeding. She was subsequently found to have pathogenic mutations in FBXL4 , a cause of mitochondrial DNA depletion syndrome-13. Intestinal dysmotility in the context of deficient mitochondrial respiration may have contributed to the development of NEC. Current paradigms call for early introduction of enteral nutrition to reinstate energy homeostasis. Enteral feeding should be administered with caution during metabolic crises of patients with mitochondrial DNA depletion syndromes.

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.

Hepatobiliary Complications in Critically Ill Patients

Critically ill patients frequently present with the systemic inflammatory response syndrome, which is largely a reflection of the liver's response to injury. Underlying hepatic congestion is a major risk factor for hypoxic liver injury, the most common cause for hepatocellular injury. Cholestatic liver injury often occurs in critically ill patients due to inhibition of farnesoid X receptor (FXR), the main regulator of bile acid handling, particularly in the liver and intestines. Additional injury to the liver occurs due to alterations in the bile acid pool with increased cytotoxic forms and disturbance in the typical processing of xenobiotics in the liver.

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.

Physiology of Stress and Use of Skin-to-Skin Care as a Stress-Reducing Intervention in the NICU

Advances in neonatal care have allowed for the increasing survival of critically ill infants. These infants experience significant stress related to painful procedures and physical separation from their parents. The purpose of this article is to describe the physiologic stress mechanisms that contribute to mortality and morbidity in infants in the NICU and the physiologic mechanisms by which skin-to-skin care (SSC) acts on the stress response system. Findings from current literature supporting the use of SSC and barriers and facilitators to implementation are reviewed. SSC is a safe and effective intervention to reduce stress for infants and their parents. Nurses play a key role in facilitating SSC to optimize outcomes of care in the NICU.

Probiotics, prebiotics and amelioration of diseases

Dysbiosis of gut microbiota is closely related to occurrence of many important chronic inflammations-related diseases. So far the traditionally prescribed prebiotics and probiotics do not show significant impact on amelioration of these diseases in general. Thus the development of next generation prebiotics and probiotics designed to target specific diseases is urgently needed. In this review, we first make a brief introduction on current understandings of normal gut microbiota, microbiome, and their roles in homeostasis of mucosal immunity and gut integrity. Then, under the situation of microbiota dysbiosis, development of chronic inflammations in the intestine occurs, leading to leaky gut situation and systematic chronic inflammation in the host. These subsequently resulted in development of many important diseases such as obesity, type 2 diabetes mellitus, liver inflammations, and other diseases such as colorectal cancer (CRC), obesity-induced chronic kidney disease (CKD), the compromised lung immunity, and some on brain/neuro disorders. The strategy used to optimally implant the effective prebiotics, probiotics and the derived postbiotics for amelioration of the diseases is presented. While the effectiveness of these agents seems promising, additional studies are needed to establish recommendations for most clinical settings.

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.

[Modern treatment of mesenteric ischemia]

Acute mesenteric ischemia is a highly morbid affliction which requires urgent care. Acute mesenteric ischemia consists in an ischemia injury of the small bowel, secondary to vascular insufficiency, either occlusive (thrombosis, embolism, arterial, venous) or non-occlusive (low flow or vasospasm). Given that the superior mesenteric artery supplies the small bowel as well as the right part of the colon, any ischemic process involving the right colon should be considered an acute mesenteric ischemia until proven otherwise. Acute mesenteric ischemia should always be suspected in the setting of a sudden, unusual and intense abdominal pain requiring opioids. Chronic mesenteric ischemia can also be revealed by postprandial abdominal pain associated with significant weight loss. The clinical presentation of mesenteric ischemia is nonspecific. Thus, a suspected diagnosis must be confirmed by imaging usually consisting in an abdominal computed tomography scan. Imaging will also provide guidance with regards to treatment decision. Organ failure, serum lactate elevation as well as bowel loop dilationper imaging are predictive of irreversible intestinal necrosis. In the presence of any of these predictive factors, surgical management should be considered. The modern treatment of mesenteric ischemia in Intestinal Stroke Centers has allowed rates of resection-free survival in nearly two-thirds of patients. The management of mesenteric ischemia relies in a combination of: (1) a medical protocol including oral/enteral antibiotics; (2) the revascularization of viable bowel and (3) the surgical resection of necrosic, non viable intestinal tissue. The inception and development of Intestinal Stroke Centers has been the cornerstone of significantly improved management and survival rates as well as crucial asset in research, specifically in the field of biomarkers associated with early diagnosis.

Effects of cisatracurium in combination with ventilation on inflammatory factors and immune variations in sepsis rats

The effects of cisatracurium in combination with ventilation on inflammatory factors and immune variations in sepsis rats were investigated. A total of 54 male Sprague-Dawley rats were selected and divided randomly into three groups: Sham group (n=6), model group (n=24) and experiment group (n=24). Rats in the model and experiment groups underwent cecal ligation and puncture (CLP) for establishment of sepsis model. Rats in experiment group additionally received cisatracurium medication in combination with ventilation for treatment. At 6, 12 and 24 h after CLP, the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and procalcitonin (PCT) in serum and the ratio of leukocyte to neutrophil in peripheral blood was also detected. Twenty-four hours later, the expression of high mobility group box 1 (HMGB1) in lung tissues and cluster of differentiation (CD) 4⁺ and CD8⁺ in T-lymphocyte subsets were also detected, and the wet/dry (W/D) ratio of lung was measured. Compared with that in model group, the levels of inflammatory factors in the experiment group were significantly decreased, while the indicators in assays of cellular immunity were obviously elevated. Ratio of leukocyte to neutrophil in peripheral blood was significantly decreased after treatment. Cisatracurium in combination with ventilation can alleviate the inflammatory injury to organs in sepsis rats through inhibiting the inflammatory responses and regulating the immune functions, which manifests a new significance in guiding the clinical diagnosis and treatment.

[Management of mesenteric ischemia in the era of intestinal stroke centers: The gut and lifesaving strategy]

Mesenteric ischemia is a gut and life-threatening, medical and surgical, digestive and vascular emergency. Mesenteric ischemia is the result of an arterial or venous occlusion, a vasospasm secondary to low-flow states in intensive care patients, aortic clamping during vascular surgery or intestinal transplantation. Progression towards mesenteric infarction and its complications is unpredictable and correlates with high rates of mortality or a high risk of short bowel syndrome in case of survival. Thus, mesenteric ischemia should be diagnosed and treated at an early stage, when gut injury is still reversible. Diagnostic workup lacks sensitive and specific clinical and biological marker. Consequently, diagnosis and effective therapy can be achieved by a high clinical suspicion and a specific multimodal management: the gut and lifesaving strategy. Based on the model of ischemic stroke centers, the need for a multidisciplinary and expert 24/24 emergency care has led, in 2016, to the inauguration of the first Intestinal Stroke Center (Structure d'urgences vasculaires intestinales [SURVI]) in France. This review highlights the pathophysiological features of chronic and acute mesenteric ischemia, as well as the diagnosis workup and the therapeutic management developed in this Intestinal Stroke Center.

Functional human 3D microvascular networks on a chip to study the procoagulant effects of ambient fine particulate matter

Exposure to ambient fine particulate matter (FPM) has been thought to be associated with cardiovascular disease.

Role of matrix metalloproteinase-8 as a mediator of injury in intestinal ischemia and reperfusion

Acute mesenteric ischemia is associated with high morbidity and mortality. In recent studies, we found that the intestine is an important source of matrix metalloproteinase (MMP)8 during intestinal injury. We hypothesized that genetic ablation or pharmacological inhibition of MMP8 would reduce intestinal injury in mice subjected to intestinal ischemia-reperfusion (I/R) injury. Male mice aged 8-12 wk were subjected to intestinal I/R injury by transient occlusion of the superior mesenteric artery for 30 min. MMP8 was inhibited by genetic and pharmacological approaches. In vivo study endpoints included several functional, histological, and biochemical assays. Intestinal sections were assessed for barrier function and expression of tight junction proteins. I/R injury led to increased intestinal and systemic expression of MMP8. This increase was associated with increased intestinal neutrophil infiltration, epithelial injury, and permeability. I/R injury was associated with increased systemic inflammation and weight loss. These parameters were ameliorated by inhibiting MMP8. I/R injury caused a loss of the tight junction protein claudin-3, which was ameliorated by genetic ablation of MMP8. MMP8 plays an important role in intestinal I/R injury through mechanisms involving increased inflammation and loss of claudin-3. Inhibition of MMP8 is a potential therapeutic strategy in this setting.-Daly, M. C., Atkinson, S. J., Varisco, B. M., Klingbeil L., Hake, P., Lahni, P., Piraino, G., Wu, D., Hogan, S. P., Zingarelli, B., Wong, H. R. Role of matrix metalloproteinase-8 as a mediator of injury in intestinal ischemia and reperfusion.

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.

Recent Advances of Mucosal Capnometry and the Perspectives of Gastrointestinal Monitoring in the Critically Ill. A Pilot Study

Mucosal capnometry involves the monitoring of partial pressure of carbon dioxide (PCO2) in mucous membranes. Different techniques have been developed and applied for this purpose, including sublingual or buccal sensors, or special gastrointestinal tonometric devices. The primary use of these procedures is to detect compensated shock in critically ill patients or patients undergoing major surgery. Compensatory mechanisms, in the early phases of shock, lead to the redistribution of blood flow towards the vital organs, within ostensibly typical macro-haemodynamic parameters. Unfortunately, this may result in microcirculatory disturbances, which can play a pivotal role in the development of organ failure. In such circumstances mucosal capnometry monitoring, at different gastrointestinal sites, can provide a sensitive method for the early diagnosis of shock. The special PCO2 monitoring methods assess the severity of ischaemia and help to define the necessary therapeutic interventions and testing of these monitors have justified their prognostic value. Gastrointestinal mucosal capnometry monitoring also helps in determining the severity of ischaemia and is a useful adjunctive in the diagnosis of occlusive splanchnic arterial diseases. The supplementary functional information increases the diagnostic accuracy of radiological techniques, assists in creating individualized treatment plans, and helps in follow-up the results of interventions. The results of a pilot study focusing on the interrelation of splanchnic perfusion and gastrointestinal function are given and discussed concerning recent advances in mucosal capnometry.

Restrictive Fluid Resuscitation Leads to Better Oxygenation than Non-Restrictive Fluid Resuscitation in Piglets with Pulmonary or Extrapulmonary Acute Respiratory Distress Syndrome

BACKGROUND

Early goal-directed therapy (EGDT) is used to reduce mortality from septic shock and could be used in early fluid resuscitation of acute respiratory distress syndrome (ARDS). The aim of the present study was to assess the effects of restrictive (RFR) and nonrestrictive fluid resuscitation (NRFR) on hemodynamics, oxygenation, pulmonary function, tissue perfusion, and inflammation in piglets with pulmonary or extrapulmonary ARDS (ARDSp and ARDSexp).

MATERIAL AND METHODS

Chinese miniature piglets (6-8 weeks; 15 ± 1 kg) were randomly divided into 2 groups (n=12/group) for establishing ARDSp and ARDSexp models, and were further divided into 2 subgroups (n=6/subgroup) for performing RFR and NRFR. Piglets were anesthetized and hemodynamic, pulmonary, and oxygenation indicators were collected at different time points for 6 hours. The goal of EGDT was set for PiCCO parameters (mean arterial pressure (MAP), urine output and cardiac index (CI), and central venous oxygen saturation (ScvO2).

RESULTS

Piglets under RFR had lower urine output compared with NRFR, as well as lower total fluid volume (P<0.05). EVLW was decreased in ARDSp+RFR and NRFR, as well as in ARDSexp+RFR, but EVLW increased in ARDSexp+NRFR (P<0.05). PaO2/FiO2 decreased in ARDSp using both methods, but was higher with RFR (P<0.05), and was increased in ARDSexp+RFR. Other pulmonary indicators were comparable. The anti-inflammatory cytokines IL-10 and LXA4 were increased in ARDSexp after RFR (P<0.05), but not in the other groups.

CONCLUSIONS

RFR led to better oxygenation in ARDSp and ARDSexp compared with NRFR, but fluid restriction improved oxygenation in ARDSexp only.

Noninvasive biomagnetic detection of intestinal slow wave dysrhythmias in chronic mesenteric ischemia

Chronic mesenteric ischemia (CMI) is a challenging clinical problem that is difficult to diagnose noninvasively. Diagnosis early in the disease process would enable life-saving early surgical intervention. Previous studies established that superconducting quantum interference device (SQUID) magnetometers detect the slow wave changes in the magnetoenterogram (MENG) noninvasively following induction of mesenteric ischemia in animal models. The purpose of this study was to assess functional physiological changes in the intestinal slow wave MENG of patients with chronic mesenteric ischemia. Pre- and postoperative studies were conducted on CMI patients using MENG and intraoperative recordings using invasive serosal electromyograms (EMG). Our preoperative MENG recordings showed that patients with CMI exhibited a significant decrease in intestinal slow wave frequency from 8.9 ± 0.3 cpm preprandial to 7.4 ± 0.1 cpm postprandial (P < 0.01) that was not observed in postoperative recordings (9.3 ± 0.2 cpm preprandial and 9.4 ± 0.4 cpm postprandial, P = 0.86). Intraoperative recording detected multiple frequencies from the ischemic portion of jejunum before revascularization, whereas normal serosal intestinal slow wave frequencies were observed after revascularization. The preoperative MENG data also showed signals with multiple frequencies suggestive of uncoupling and intestinal ischemia similar to intraoperative serosal EMG. Our results showed that multichannel MENG can identify intestinal slow wave dysrhythmias in CMI patients.

Gastrointestinal ischemia monitoring through impedance spectroscopy as a tool for the management of the critically ill

Impedance spectroscopy (IS) has been proposed as a tool for monitoring mucosal tissue ischemia and damage in the gut of critically ill patients resulting from shock and hypoperfusion. A specific device and system have been developed and tested for this specific application over the past 12 years by our research group. This paper reviews previously published studies as well as unpublished experimental results, and puts the whole in context and perspective to help understand this technology. Results presented include summaries of gastric reactance measurement understanding, in vivo measurements in animal models, clinical significance of the measurement, and future perspectives of clinical use of this technology. All of the experimental work done to date has been designed to determine the evolving device prototypes' performance and limitations from an instrumentation point of view. Although there are still questions to be answered with regard to the IS measurement, we conclude that we have reached enough confidence in the measurement and the device's performance and safety to begin clinically oriented research to learn how this technology may be useful in the diagnosis and management of different populations of the critically ill.

Man is the new mouse: Elective surgery as a key translational model for multi-organ dysfunction and sepsis

Translational research in critically ill human patients presents many methodological challenges. Diagnostic uncertainty, coupled with poorly defined comorbidities, make the identification of a suitable control population for case-control investigations an arguably insurmountable challenge. Healthy volunteer experiments using endotoxin infusion as an inflammatory model are methodologically robust, but fail to replicate the onset of, and diverse therapeutic interventions associated with, sepsis/trauma. Animal models are also limited by many of these issues. Major elective surgery addresses many of these shortfalls and offers a key model for exploring the human biology underlying the sepsis syndrome. Surgery triggers highly conserved features of the human inflammatory response that are common to both tissue damage and infection. Surgical patients sustain a predictable and relatively high incidence of sepsis, particularly within the 'higher risk' group. The collection of preoperative samples enables each patient to act as their own control. Thus, the surgical model offers unique and elegant experimental design features that provide an important translational bridge between the basic biological understanding afforded by animal laboratory models and the de novo presentation of human sepsis.

Effect of da-cheng-qi decoction on the repair of the injured enteric nerve-interstitial cells of cajal-smooth muscle cells network in multiple organ dysfunction syndrome

Wistar rats were randomly divided into control group, multiple organ dysfunction syndrome (MODS) group, and Da-Cheng-Qi decoction (DCQD) group. The network of enteric nerves-interstitial cells of Cajal- (ICC-) smooth muscle cells (SMC) in small intestine was observed using confocal laser scanning microscopy and transmission electron microscopy. The results showed that the numbers of cholinergic/nitriergic nerves, and the deep muscular plexus of ICC (ICC-DMP) and connexin43 (Cx43) in small intestine with MODS were significantly decreased. The network integrity of enteric nerves-ICC-SMC was disrupted. The ultrastructures of ICC-DMP, enteric nerves, and SMC were severely damaged. After treatment with DCQD, the damages were repaired and the network integrity of enteric nerves ICC-SMC was significantly recovered. In conclusion, the pathogenesis of gastrointestinal motility dysfunction in MODS in part may be due to the damages to enteric nerves-ICC-SMC network and gap junctions. The therapeutic mechanism of DCQD in part may be that it could repair the damages and maintain the integrity of enteric nerves ICC-SMC network.

Monitoring CO2 in shock states

The primary end point when treating acute shock is to restore blood circulation, mainly by reaching macrocirculatory parameters. However, even if global haemodynamic goals can be achieved, microcirculatory perfusion may remain impaired, leading to cellular hypoxia and organ damage. Interestingly, few methods are currently available to measure the adequacy of organ blood flow and tissue oxygenation. The rise in tissue partial pressure of carbon dioxide (CO2) has been observed when tissue perfusion is decreased. In this regard, tissue partial pressure of CO2 has been proposed as an early and reliable marker of tissue hypoxia even if the mechanisms of tissue partial pressure in CO2 rise during hypoperfusion remain unclear. Several technologies allow the estimation of CO2 content from different body sites: vascular, tissular (in hollow organs, mucosal or cutaneous), and airway. These tools remain poorly evaluated, and some are used but are not widely used in clinical practice. The present review clarifies the physiology of increasing tissue CO2 during hypoperfusion and underlines the specificities of the different technologies that allow bedside estimation of tissue CO2 content.

Gastro-intestinal vascular emergencies

Gastro-Intestinal Vascular Emergencies include all digestive ischaemic injuries related to acute or chronic vascular and/or haemodynamic diseases. Gastro-intestinal ischaemic injuries can be occlusive or non-occlusive, arterial or venous, localized or generalized, superficial or transmural and share the risks of infarction, organ failure and death. The diagnosis must be suspected, at the initial presentation of any sudden, continuous and unusual abdominal pain, contrasting with normal physical examination. Risk factors are often unknown at presentation and no biomarker is currently available. The diagnosis is confirmed by abdominal computed tomography angiography identifying intestinal ischaemic injury, either with vascular occlusion or in a context of low flow. Recent knowledge in the pathophysiology of acute mesenteric ischaemia, clinical experience and existing recommendations have generated a multimodal and multidisciplinary management strategy. Based on the gastro-intestinal viability around a simple algorithm, and coordinated by gastroenterologists, the dual aim is to avoid large intestinal resections and death.

Newer monitoring techniques to determine the risk of necrotizing enterocolitis

Necrotizing enterocolitis affects up to 10% of neonates who are born weighing less than 1500 g. It has a high rate of morbidity and mortality, and predicting infants who will be affected has so far been unsuccessful. In this article, a number of new methods are discussed from the literature to determine if any currently available techniques may allow for the identification of patients who are at increased risk for developing this potentially lethal disease.

Effect of thoracic epidural anaesthesia on splanchnic blood flow

BACKGROUND

Thoracic epidural anaesthesia (TEA) is used widely in colorectal surgery. However, there is increasing concern that epidurals are associated with postoperative hypotension, mediating a potential reduction in splanchnic flow. The aim was to review the literature on the effects of TEA on splanchnic blood flow.

METHODS

PubMed and Cochrane databases were searched. Search terms used were: English language, 'thoracic epidural splanchnic flow', 'thoracic epidural gut blood flow', 'thoracic epidural intestinal blood flow' and 'thoracic epidural colonic blood flow'. Abstracts were reviewed by two independent researchers and irrelevant studies excluded. The full text of the remaining articles was then retrieved.

RESULTS

Twenty-two abstracts were reviewed and three excluded. Nineteen papers were reviewed in full and seven irrelevant articles excluded. Five human studies investigated the effects of TEA on splanchnic flow. Two studies measured splanchnic flow directly and found an epidural-mediated fall in flow, unresponsive to intravenous fluids and requiring vasopressors or inotropes to restore baseline flow. The remaining three studies had inconsistent findings and haemodynamic stability was maintained. The seven animal studies identified were heterogeneous in both methodology and findings. Three suggested a protective role for thoracic epidurals in septic shock and pancreatitis.

CONCLUSION

These findings are inconsistent; however, the two studies that investigated the effects of vasoconstrictors on splanchnic blood flow directly both found a significant epidural-mediated reduction in splanchnic blood flow that was unresponsive to fluid therapy.

Monitoring in the intensive care

In critical care, the monitoring is essential to the daily care of ICU patients, as the optimization of patient's hemodynamic, ventilation, temperature, nutrition, and metabolism is the key to improve patients' survival. Indeed, the decisive endpoint is the supply of oxygen to tissues according to their metabolic needs in order to fuel mitochondrial respiration and, therefore, life. In this sense, both oxygenation and perfusion must be monitored in the implementation of any resuscitation strategy. The emerging concept has been the enhancement of macrocirculation through sequential optimization of heart function and then judging the adequacy of perfusion/oxygenation on specific parameters in a strategy which was aptly coined “goal directed therapy.” On the other hand, the maintenance of normal temperature is critical and should be regularly monitored. Regarding respiratory monitoring of ventilated ICU patients, it includes serial assessment of gas exchange, of respiratory system mechanics, and of patients' readiness for liberation from invasive positive pressure ventilation. Also, the monitoring of nutritional and metabolic care should allow controlling nutrients delivery, adequation between energy needs and delivery, and blood glucose. The present paper will describe the physiological basis, interpretation of, and clinical use of the major endpoints of perfusion/oxygenation adequacy and of temperature, respiratory, nutritional, and metabolic monitorings.

Incidence of gastric mucosal injury as measured by reactance in critically ill patients

Gastric reactance has been proposed as a measure of mucosal ischemic injury in the critically ill. The purpose of this study was to evaluate the incidence of gastric mucosal injury as measured by gastric reactance in different subgroups of critical patients. We studied 100 adult patients admitted to 7 different hospital intensive care units, requiring a nasogastric tube. Gastric impedance measurements were continuously obtained from each patient for 24 hours. Patients were managed based on conventional protocols by hospital staff, blinded to the changes in gastric impedance parameters. The low-frequency central reactance (X L) reflects tissue edema caused by prolonged ischemia. The previously reported threshold of X L ≥ 13 - jΩ was used to classify injured mucosa; 80% of all patients had mean X L above this threshold. No significant differences were found in the incidence of mucosal ischemia between medical versus surgical, hemodynamic versus respiratory or neurological patients. Significant lower urine output was found in patients with X L above threshold (P < .01); also, there was a significant effect of fluid balance in those patients (P < .05). More complicated patients had higher average reactance. This study shows that gastric ischemia as estimated by gastric reactance has a very high incidence in the critically ill, independently of the reason for admission. High reactance is related with higher morbidity in agreement with other reports using different methods of assessing splanchnic hypoperfusion in this patient population.

Bladder mucosal CO2 compared with gastric mucosal CO2 as a marker for low perfusion states in septic shock

Recent reports indicate the possible role of bladder CO(2) as a marker of low perfusion states. To test this hypothesis, shock was induced in six beagle dogs with 1 mg/kg of E. coli lipopolysaccharide, gastric CO(2) (CO(2)-G) was measured with a continuous monitor, and a pulmonary catheter was inserted in the bladder to measure CO(2) (CO(2)-B). Levels of CO(2)-B were found to be lower than those of CO(2)-G, with a mean difference of 36.8 mmHg (P < 0.001), and correlation between both measurements was poor (r(2) = 0.16). Even when the correlation between CO(2)-G and ΔCO(2)-G was narrow (r(2) = 0.86), this was not the case for the relationship between CO(2)-B and ΔCO(2)-B (r(2) = 0.29). Finally, the correlation between CO(2)-G and base deficit was good (r(2) = 0.45), which was not the case with the CO(2)-B correlation (r(2) = 0.03). In our experience, bladder CO(2) does not correlate to hemodynamic parameters and does not substitute gastric CO(2) for detection of low perfusion states.

Effects of L-arginine pretreatment on nitric oxide metabolism and hepatosplanchnic perfusion during porcine endotoxemia

BACKGROUND

Sepsis is accompanied by an increased need for and a decreased supply of arginine, reflecting a condition of arginine deficiency.

OBJECTIVE

The objective was to evaluate the effects of l-arginine pretreatment on arginine-nitric oxide (NO) production and hepatosplanchnic perfusion during subsequent endotoxemia.

DESIGN

In a randomized controlled trial, pigs (20-25 kg) received 3 μg . kg(-1) . min(-1) lipopolysaccharide (LPS; 5 endotoxin units/ng) intravenously and saline resuscitation. l-Arginine (n = 8; 5.3 μmol . kg(-1) . min(-1)) or saline (n = 8) was infused starting 12 h before LPS infusion and continued for 24 h after the endotoxin infusion ended. Whole-body appearance rates, portal-drained viscera (PDV), and liver fluxes of arginine, citrulline, NO, and arginine de novo synthesis were measured by using stable-isotope infusion of [(15)N(2)]arginine and [(13)C-(2)H(2)]citrulline. Hepatosplanchnic perfusion was assessed by using a primed continuous infusion of para-aminohippuric acid and jejunal intramucosal partial pressure of carbon dioxide and was related to systemic hemodynamics.

RESULTS

Arginine supplementation before LPS increased whole-body NO production in the PDV but not in the liver. Furthermore, it increased blood flow in the portal vein but not in the aorta and hepatic artery. During endotoxin infusion, arginine pretreatment was associated with an increased whole-body arginine appearance and NO production in the gut. Additional effects included a preserved mean arterial pressure, the prevention of an increase in pulmonary arterial pressure, an attenuated metabolic acidosis, and an attenuated increase in the intramucosal partial pressure of carbon dioxide.

CONCLUSION

Arginine treatment starting before endotoxemia appears to be beneficial because it improves hepatosplanchnic perfusion and oxygenation during prolonged endotoxemia, probably through an enhancement in NO synthesis, without causing deleterious systemic side effects.

Minimized and conventional cardiopulmonary bypass damage intestinal mucosal integrity

OBJECTIVES

Previous studies have suggested that gastrointestinal integrity is compromised after cardiopulmonary bypass (CPB). We compared the effects of prolonged minimized (MCPB) and conventional CPB (CCPB) on intestinal mucosal integrity by determining mucosal damage, epithelial cell proliferation rate and distribution of tight junction proteins in a porcine model.

DESIGN

Fourteen animals were randomly assigned to undergo 240 minutes of mild hypothermic MCPB or CCPB. Ileal and colonic biopsies were obtained prior and at the end of CPB. Mucosal damage was determined under light microscopic evaluation. Immunohistochemistry was used to investigate epithelial expression of Ki-67 as a measure of cell proliferation rate and claudin-1, 2, 3, 4, 5, and 7 as elements of tight junctions.

RESULTS

In colonic biopsies, independent of the circuit type used, moderate mucosal damage was observed as indicated by focal epithelial damage, increased epithelial cell proliferation and decreased expression of tight junction protein claudin-4.

CONCLUSIONS

Colonic mucosal damage was observed similarly in MCPB and CCPB. Based on these results, the effects of MCPB on intestinal mucosal stability are similar to those of CCPB.

Small bowel necrosis in association with jejunal tube feeding

Early recognition and appropriate treatment of bowel ischemia is imperative to reduce morbidity and mortality in any situation, including in conjunction with enteral tube feeding. GI intolerance can manifest as increased nasogastric tube output, unexplained abdominal pain/distension, and pneumatosis intestinalis in critically ill patients who are on tube feedings and may be experiencing periods of splanchnic hypotension. Recommendations are to immediately cease tube feedings when these signs and symptoms are recognized, and total parenteral nutrition should be considered. Surgical exploration during the early stages should be considered to prevent the usual and fatal catastrophic cascade of widespread bowl infarction.

Goal-directed haemodynamic therapy and gastrointestinal complications in major surgery: a meta-analysis of randomized controlled trials

Postoperative gastrointestinal (GI) dysfunction is one of the most frequent complications in surgical patients. Most cases are associated with episodes of splanchnic hypoperfusion due to hypovolaemia or cardiac dysfunction. It has been suggested that perioperative haemodynamic goal-directed therapy (GDT) may reduce the incidence of these complications in cardiac surgery, and other surgery, but clear evidence is lacking. We have undertaken a meta-analysis of the effects of GDT on postoperative GI and liver complications. A systematic search, using MEDLINE, EMBASE, and The Cochrane Library databases, was performed. Sixteen randomized controlled trials (3410 participants) met the inclusion criteria. Data synthesis was obtained using odds ratio (OR) with 95% confidence interval (CI) by random-effects model. Statistical heterogeneity was assessed by Q and I2 statistics. GI complications were ranked as major (required radiological or surgical intervention or life-threatening condition) or minor (no or only pharmacological treatment required). Major GI complications were significantly reduced by GDT when compared with a control group (OR, 0.42; 95% CI, 0.27-0.65). Minor GI complications were also significantly decreased in the GDT group (OR, 0.29; 95% CI, 0.17-0.50). Treatment did not reduce hepatic injury rate (OR, 0.54; 95% CI, 0.19-1.55). Quality sensitive analyses confirmed the main overall results. In patients undergoing major surgery, GDT, by maintaining an adequate systemic oxygenation, can protect organs particularly at risk of perioperative hypoperfusion and is effective in reducing GI complications.

Hepatic and renal protection during cardiac surgery

Hepatic injury in cardiac surgery is a rare complication but is associated with significant morbidity and mortality. A high index of suspicion postoperatively will lead to earlier treatment directed at eliminating or minimizing ongoing hepatic injury while preventing additional metabolic stress from ischemia, hemorrhage, or sepsis. The evidence-basis for perioperative renal risk factors remains hampered by the inconsistent definitions for renal injury. Although acute kidney injury (as defined by the Risk, Injury, Failure, Loss, End-stage criteria) has become accepted, it does not address pathogenesis and bears little relevance to cardiac surgery. Although acute renal failure requiring renal replacement therapy after cardiac surgery is rare, it has a devastating impact on morbidity and mortality, and further studies on protective strategies are essential.

Correlation of abdominal site near-infrared spectroscopy with gastric tonometry in infants following surgery for congenital heart disease

OBJECTIVE

Splanchnic oximetry, as measured by near-infrared spectroscopy (NIRS), correlates with gastric tonometry as a means of assessing regional (splanchnic) oxygenation and perfusion.

DESIGN

Prospective, data-gathering study.

SETTING

Pediatric cardiac intensive care unit in a tertiary care children's hospital.

SUBJECTS

Neonates and infants with congenital heart disease who underwent catheter intervention or surgical repair requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Twenty neonates and infants were studied within 48 hrs of surgery. We measured somatic saturation (rSO2) via NIRS sensors placed over the anterior abdomen (splanchnic bed) and dorsal lateral flank (renal bed). Somatic rSO2 readings were paired with simultaneous points of intramucosal gastric pH (pHi), measured by tonometry. The rSO2 readings were paired with serum lactate and measurements of systemic mixed venous saturation (SVO2). There was strong correlation between the abdominal rSO2 and pHi (r = .79; p < .0001) as well as between abdominal rSO2 and SVO2 (r = .89; p < .0001). There was also significant negative correlation between the abdominal rSO2 and serum lactate (r = .77; p < .0001). Correlations between the dorsal lateral (renal) rSO2 measurements and serum lactate and SVO2 were also significant but not as strong.

CONCLUSIONS

Abdominal site rSO2, measured in infants with either single or biventricular physiology, exhibits a strong correlation with gastric pHi as well as with serum lactate and SVO2. The results indicate that rSO2 measurements over the anterior abdominal wall correlate more strongly than flank rSO2 with regard to systemic indices of oxygenation and perfusion. This study suggests that the NIRS monitor is a valid modality to obtain an easy, immediate, and noninvasive measurement of splanchnic rSO2 in infants following cardiac surgery for congenital heart disease.