Intravenous iloprost increases mesenteric blood flow in experimental acute nonocclusive mesenteric ischemia

Evaluation of non-occlusive mesenteric ischemia for burn patients - A matched-pair analysis and treatment algorithm

BACKGROUND

Burn injuries may cause gastrointestinal dysfunction leading to intestinal barrier dysfunction, abdominal compartment syndrome, and acute mesenteric ischemia. In the absence of major vascular occlusion, non-occlusive mesenteric ischemia (NOMI) often occurs in critically ill intensive-care burn patients.

METHODS

A retrospective descriptive analysis of the burn registry of the Department of Plastic, Aesthetic, Hand and Reconstructive Surgery of Hannover Medical School was performed from 1st January 2018 to 1st May 2024. Burn patients with NOMI were matched with burn patients who did not acquire acute mesenteric ischemia based on key variables and shared characteristics.

RESULTS

A total of 20 patients were included in this study. Patients with NOMI showed a statistically significant elevation in serum lactate (p = 0.005) and were most likely to be in a shock state requiring vasopressors (p = 0.047). Overall prognosis was poor for the NOMI cohort, 80 % of whom had a fatal result (p = 0.024). A total of four patients received intra-arterial administration of alprostadil.

CONCLUSIONS

NOMI represents a potentially fatal condition for the burn patient. The current lack of sensitive biomarkers and accurate diagnostic tools for the early detection of NOMI onset is a major factor behind the overall poor prognosis. We propose the intra-arterial administration of alprostadil as a novel approach to targeted treatment for NOMI.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Iloprost reduces colonic injury in ischemic colitis in rats

PURPOSE

Evaluate the effects of iloprost administration in the early period of ischemic colitis and the mechanism that how these effects develop.

METHODS

Thirty two Wistar albino female rats with an average weight of 220g were divided into four groups of eight rats. In group 1 the rats were given iloprost and sacrificed after 24 hours and in group 2 they were sacrificed after 24 hours without any iloprost. The rats in group 3 were administrated iloprost and sacrificed after 72 hours and in group 4 they were sacrificed at 72th hour without iloprost. The differences between the groups as tissue damage, vascularization or apoptosis were assessed statistically.

RESULTS

Oxidative damage and apoptosis were less pronounced and vascularization was better developed in rats that were given iloprost and sacrificed at 24th hour later in contrast to the rats that were not treated with iloprost. But there was no statistical difference among the groups at 72th hour.

CONCLUSION

Iloprost inhibited leucocyte infiltration, decreased proinflammatory cytokines and enhanced angiogenesis so that the oxidative stress and inflammatory response decreased resulting in lesser tissue damage.

Acute mesenteric ischemia after cardio-pulmonary bypass surgery

Acute mesenteric ischemia (AMI) is a highly-lethal surgical emergency. Several pathophysiologic events (arterial obstruction, venous thrombosis and diffuse vasospasm) lead to a sudden decrease in mesenteric blood flow. Ischemia/reperfusion syndrome of the intestine is responsible for systemic abnormalities, leading to multi-organ failure and death. Early diagnosis is difficult because the clinical presentation is subtle, and the biological and radiological diagnostic tools lack sensitivity and specificity. Therapeutic options vary from conservative resuscitation, medical treatment, endovascular techniques and surgical resection and revascularization. A high index of suspicion is required for diagnosis, and prompt treatment is the only hope of reducing the mortality rate. Studies are in progress to provide more accurate diagnostic tools for early diagnosis. AMI can complicate the post-operative course of patients following cardio-pulmonary bypass (CPB). Several factors contribute to the systemic hypo-perfusion state, which is the most frequent pathophysiologic event. In this particular setting, the clinical presentation of AMI can be misleading, while the laboratory and radiological diagnostic tests often produce inconclusive results. The management strategies are controversial, but early treatment is critical for saving lives. Based on the experience of our team, we consider prompt exploratory laparotomy, irrespective of the results of the diagnostic tests, is the only way to provide objective assessment and adequate treatment, leading to dramatic reduction in the mortality rate.

Negative mesenteric effects of lung recruitment maneuvers in oleic acid lung injury are transient and short lasting

OBJECTIVE

To test the hypothesis that repeated recruitment maneuvers (RMs) have sustained negative effects on mesenteric circulation, metabolism, and oxygenation 60 mins after RMs in pigs with oleic acid lung injury. Further, we aimed to test the hypothesis that an infusion of prostacyclin (PC) at 33 ng.kg.min would attenuate such possible negative mesenteric effects.

DESIGN

Randomized, experimental, controlled study.

SETTING

University hospital animal laboratory.

SUBJECTS

A total of 31 anesthetized, fluid-resuscitated pigs with oleic acid lung injury.

INTERVENTIONS

: Animals were randomized to one of the following four groups: a control group (n = 7) that received no intervention, recruitment group (n = 8) that underwent the RM sequence, a prostacyclin group (n = 8) that received an infusion of PC, and a recruitment-prostacyclin group (n = 8) that received an infusion of PC and concomitant RM sequence.

MEASUREMENTS AND MAIN RESULTS

We measured systemic and mesenteric hemodynamic variables, jejunal mucosal perfusion, mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygen delivery, uptake, and extraction ratio. Five minutes after RMs, mesenteric oxygen extraction ratio and mesenteric lactate flux were more prominently increased in the recruitment group, giving evidence of worsened mesenteric conditions after RMs. These signs of worsened conditions were further supported by more decreased jejunal tissue oxygen tension and portal vein oxygen saturation in the recruitment group. PC preserved mesenteric oxygenation, as indicated by less of a decrease in portal vein oxygen saturation at the time corresponding to 5 mins after RM and less of a decrease in mesenteric oxygen delivery at the time corresponding to 15 mins after RM. PC preserved mesenteric oxygenation as indicated by less of a decrease in portal vein oxygen saturation at 5 mins after RM and an attenuated increase in mesenteric oxygen extraction ratio at 5 mins after RM. There was a trend toward worsened jejunal mucosal perfusion, although not significant.

CONCLUSIONS

In an oleic acid lung injury model, three repeated RMs did not improve systemic oxygenation or lung mechanics. Negative effects on mesenteric oxygenation and metabolism were transient and short lasting. The intestinal effects of PC during RMs were minor and opposing, showing preserved oxygenation but a trend toward worsened mucosal perfusion.

Update in management of mesenteric ischemia

Mesenteric ischemia disorders are precipitated by a circulation insufficiency event that deprives one or several abdominal organs of adequate respiration to meet metabolic demands. Although mesenteric ischemia occurs infrequently, the mortality rate is from 60% to 100%, depending on the source of obstruction. The successful outcome is dependent upon a high index of suspicion and prompt management. We briefly review the pathophysiology and presentation of the various ischemic entities and review the current state of the art in diagnosis and treatment. Despite advances in both diagnosis and treatment, prompt diagnosis and supportive care remain critical for successful outcome. New imaging techniques, endovascular therapy and emerging research may improve our approach to this deadly condition.

Small-dose epoprostenol decreases systemic oxygen consumption and splanchnic oxygen extraction during normothermic cardiopulmonary bypass

Normothermic, nonpulsatile cardiopulmonary bypass (CPB) impairs systemic and splanchnic oxygen transport and increases gastrointestinal permeability. It is an important therapeutic goal to avoid splanchnic dysoxia during CPB. Small-dose prostacyclin therapy improves splanchnic oxygen transport and microcirculation in septic patients. In this study, we sought to determine if during cardiac surgery, the prostacyclin analog epoprostenol improves the balance of systemic and splanchnic oxygen transport. Eighteen patients undergoing cardiac valve replacement were randomized to receive either epoprostenol (3 ng x kg(-1) x min(-1)) or placebo during, and for 1 hour after, surgery. Systemic and splanchnic oxygen delivery, consumption, and extraction and arterial, mixed venous, and hepato-venous lactate concentrations were measured before, during, and after CPB. Gastrointestinal permeability was measured 1 day before and 1 day after surgery using the triple sugar permeability test. During CPB, the epoprostenol group had decreased systemic oxygen consumption and splanchnic oxygen extraction (P = 0.024). These effects were not present 1 hour after the end of epoprostenol infusion. The study was not adequately powered to determine whether epoprostenol altered the trend towards increased lactate metabolism and increased postoperative gastrointestinal permeability, nor could we demonstrate any differences between groups in clinically relevant end-points. In conclusion, these findings suggest that during normothermic CPB, small-dose epoprostenol therapy may reduce systemic oxygen consumption and splanchnic oxygen extraction.

Review article: diagnosis and management of mesenteric ischaemia with an emphasis on pharmacotherapy

Mesenteric ischaemia results from decreased blood flow to the bowel, causing cellular injury from lack of oxygen and nutrients. Acute mesenteric ischaemia (AMI) is an uncommon disorder with high morbidity and mortality, but outcomes are improved with prompt recognition and aggressive treatment. Five subgroups of AMI have been identified, with superior mesenteric artery embolism (SMAE) the most common. Older age and cardiovascular disease are common risk factors for AMI, excepting acute mesenteric venous thrombosis (AMVT), which affects younger patients with hypercoaguable states. AMI is characterized by sudden onset of abdominal pain; a benign abdominal exam may be observed prior to bowel infarction. Conventional angiography and more recently, computed tomography angiography, are the cornerstones of diagnosis. Correction of predisposing conditions, volume resuscitation and antibiotic treatment are standard treatments for AMI, and surgery is mandated in the setting of peritoneal signs. Intra-arterial vasodilators are used routinely in the treatment of non-occlusive mesenteric ischaemia (NOMI) and also are advocated in the treatment of occlusive AMI to decrease associated vasospasm. Thrombolytics have been used on a limited basis to treat occlusive AMI. A variety of agents have been studied in animal models to treat reperfusion injury, which sometimes can be more harmful than ischaemic injury. Chronic mesenteric ischaemia (CMI) usually is caused by severe obstructive atherosclerotic disease of two or more splanchnic vessels, presents with post-prandial pain and weight loss, and is treated by either surgical revascularization or percutaneous angioplasty and stenting.

Mesenteric ischemia

MI remains a highly lethal entity. Improving survival requires an aggressive, multidisciplinary approach. High-risk patients with severe abdominal pain and a paucity of physical findings should be undergo emergent imaging in a search for this disease. Improvements in laboratory tests and advances in imaging techniques may improve the ability to diagnose MI earlier in its course, before irreversible damage has occurred. Many treatment modalities are available and should be tailored to each individual case. By recognizing and preventing ischemia-reperfusion injury,the cycle of protracted complications may be broken. A decrease in the mortality from MI finally is occurring. Early recognition and aggressive treatment finally may allow clinicians to have a marked impact on patient survival.