[Multiple organ failure. Mechanisms, clinical manifestations and treatment strategies]

Auxiliary activation of the complement system and its importance for the pathophysiology of clinical conditions

Activation and regulation of the cascade systems of the blood (the complement system, the coagulation/contact activation/kallikrein system, and the fibrinolytic system) occurs via activation of zymogen molecules to specific active proteolytic enzymes. Despite the fact that the generated proteases are all present together in the blood, under physiological conditions, the activity of the generated proteases is controlled by endogenous protease inhibitors. Consequently, there is remarkable little crosstalk between the different systems in the fluid phase. This concept review article aims at identifying and describing conditions where the strict system-related control is circumvented. These include clinical settings where massive amounts of proteolytic enzymes are released from tissues, e.g., during pancreatitis or post-traumatic tissue damage, resulting in consumption of the natural substrates of the specific proteases and the available protease inhibitor. Another example of cascade system dysregulation is disseminated intravascular coagulation, with canonical activation of all cascade systems of the blood, also leading to specific substrate and protease inhibitor elimination. The present review explains basic concepts in protease biochemistry of importance to understand clinical conditions with extensive protease activation.

Second hit phenomenon: existing evidence of clinical implications

The last two decades extensive research evidence has been accumulated regarding the pathophysiology of trauma and the sequelae of interventions that follow. Aim of this analysis has been to collect and categorise the existing data on the so-called "second hit" phenomenon that includes the biochemical and physiologic alterations occurring in patients having surgery after major trauma. Articles were extracted from the PubMed database and the retrieved reports were included in the study only if pre-specified eligibility criteria were fulfilled. Moreover, a constructed questionnaire was utilised for quality assessment of the outcomes. Twenty-six articles were eligible for the final analysis, referring to a total of 8262 patients that underwent surgery after major trauma. Sixteen retrospective clinical studies including 7322 patients and 10 prospective ones, including 940 patients were evaluated. Several variables able to reproduce a post-operative second hit were identified; mostly related to pulmonary dysfunction, coagulopathy, fat or pulmonary embolism, and the inflammatory immune system. Indicative conclusions were extracted, as well as the need for further prospective randomised trials. Suggestions on the content and the rationale of future studies are provided.

Inflammation: a way to understanding the evolution of portal hypertension

BACKGROUND

Portal hypertension is a clinical syndrome that manifests as ascites, portosystemic encephalopathy and variceal hemorrhage, and these alterations often lead to death.

HYPOTHESIS

Splanchnic and/or systemic responses to portal hypertension could have pathophysiological mechanisms similar to those involved in the post-traumatic inflammatory response.The splanchnic and systemic impairments produced throughout the evolution of experimental prehepatic portal hypertension could be considered to have an inflammatory origin. In portal vein ligated rats, portal hypertensive enteropathy, hepatic steatosis and portal hypertensive encephalopathy show phenotypes during their development that can be considered inflammatory, such as: ischemia-reperfusion (vasodilatory response), infiltration by inflammatory cells (mast cells) and bacteria (intestinal translocation of endotoxins and bacteria) and lastly, angiogenesis. Similar inflammatory phenotypes, worsened by chronic liver disease (with anti-oxidant and anti-enzymatic ability reduction) characterize the evolution of portal hypertension and its complications (hepatorenal syndrome, ascites and esophageal variceal hemorrhage) in humans.

CONCLUSION

Low-grade inflammation, related to prehepatic portal hypertension, switches to high-grade inflammation with the development of severe and life-threatening complications when associated with chronic liver disease.

Cytokine patterns after tourniquet-induced skeletal muscle ischaemia reperfusion in total knee replacement

OBJECTIVE

Extremity surgery performed under tourniquet control causes one of the most common forms of skeletal muscle ischaemia-reperfusion injury in clinical practice. The aim of this study was to investigate the systemic and local inflammatory response after tourniquet-induced skeletal muscle ischaemia-reperfusion injury in patients undergoing total knee replacement. It was our hypothesis that local inflammatory responses in a surgical wound under tourniquet-induced ischaemia cause an excessive overflow of cytokines to the systemic circulation in the reperfusion phase.

MATERIAL AND METHODS

Blood was sampled before and after surgery in nine patients given total knee replacement. Samples from ischaemic and non-ischaemic limbs and from drained blood were analysed for pro-inflammatory and anti-inflammatory cytokines.

RESULTS

Surgery induced significant increases of IL-6 (p = 0.007) in the non-ischaemic (systemic) limb and in drained blood (p = 0.032), with highest levels 4 h after operation. The increased IL-6 in the ischaemic limb was non-significant. IL-1 beta was not detectable under surgery, from either the traumatized limb or from the non-traumatized limb, nor were TNFalpha and IL-10 significantly influenced by surgery.

CONCLUSIONS

Knee replacement trauma performed under ischaemia, is associated with modest systemic inflammatory reactions with no spillover of increased IL-6 from the traumatized area in the reperfusion phase.

[The importance of cytokines in the posttraumatic inflammatory reaction]

Alterations in the immune response after multiple trauma, posttraumatic sepsis and surgery are recognized as physiological reactions of the organism to restore homeostasis. The level of these immunological changes correlates with the degree of tissue damage as well as with the severity of haemorrhage and ischaemia. Cytokines are known to be integral components of this immune response. The local release of pro- and antiinflammatory cytokines after severe trauma indicates their potential to induce systemic immunological alterations. It appears that the balance or imbalance of these different cytokines partly controls the clinical course in these patients. Overproduction of either proinflammatory cytokines or antiinflammatory mediators may result in organ dysfunction. Whereas predominance of the proinflammatory response leads to the systemic inflammatory response syndrome (SIRS), the antiinflammatory reaction may result in immune suppression with an enhanced risk of infectious complications. Systemic inflammation, as well as immune suppression, are thought to play a decisive role in the development of multiple organ dysfunction syndrome (MODS). The major proinflammatory cytokines involved in the response to trauma and surgery include tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6 and IL-8. These cytokines, which are predominantly produced by monocytes and macrophages, mediate a variety of frequently overlapping effects, and their actions can be additive. TNF-alpha and IL-1beta are early regulators of the immune response and both induce the release of secondary cytokines, such as IL-6 and IL-8. IL-10 is an antiinflammatory cytokine which reduces the synthesis of proinflammatory mediators. Other important antiinflammatory mediators are soluble TNF receptors and the IL-1 receptor antagonist, which interfere with the effects of TNF-alpha and IL-1beta.Early evaluation of the prognosis of polytraumatized patients and assessment of their clinical status is known to be difficult. Therefore, in several clinical studies, cytokine levels during the posttraumatic course have been determined with the aim of finding predictive markers of patient outcome. The purpose of this review was to highlight our current knowledge on the interaction of posttraumatic immune reactivity and the development of complications. A better understanding of these mechanisms might lead to the introduction of preventive and therapeutic strategies into clinical practice.

Pathophysiology of polytrauma

Immediate and early trauma deaths are determined by primary brain injuries, or significant blood loss (haemorrhagic shock), while late mortality is caused by secondary brain injuries and host defence failure. First hits (hypoxia, hypotension, organ and soft tissue injuries, fractures), as well as second hits (e.g. ischaemia/reperfusion injuries, compartment syndromes, operative interventions, infections), induce a host defence response. This is characterized by local and systemic release of pro-inflammatory cytokines, arachidonic acid metabolites, proteins of the contact phase and coagulation systems, complement factors and acute phase proteins, as well as hormonal mediators: it is defined as systemic inflammatory response syndrome (SIRS), according to clinical parameters. However, in parallel, anti-inflammatory mediators are produced (compensatory anti-inflammatory response syndrome (CARS). An imbalance of these dual immune responses seems to be responsible for organ dysfunction and increased susceptibility to infections. Endothelial cell damage, accumulation of leukocytes, disseminated intravascular coagulation (DIC) and microcirculatory disturbances lead finally to apoptosis and necrosis of parenchymal cells, with the development of multiple organ dysfunction syndrome (MODS), or multiple organ failure (MOF). Whereas most clinical trials with anti-inflammatory, anti-coagulant, or antioxidant strategies failed, the implementation of pre- and in-hospital trauma protocols and the principle of damage control procedures have reduced post-traumatic complications. However, the development of immunomonitoring will help in the selection of patients at risk of post-traumatic complications and, thereby, the choice of the most appropriate treatment protocols for severely injured patients.

[Acute liver failure. Current aspects of diagnosis and therapy]

Disturbances of some partial liver functions, such as synthesis, excretion, or biotransformation of xenobiotics, are important for prognosis and ultimate survival in patients presenting with multiple organ dysfunction on the intesive care unit (ICU). The incidence of liver dysfunction is underestimated when traditional "static" measures such as serum-transaminases or bilirubin as opposed to "dynamic" tests, such as clearance tests, are used to diagnose liver dysfunction. Similar to the central role of the failing liver in MODS, extrahepatic complications, such as hepatorenal syndrome and brain edema develop in acute or fulminant hepatic failure and determine the prognosis of the patient. This is reflected in the required presence of hepatic encephalopathy in addition to hyperbilirubinemia and coagulopathy for the diagnosis of acute liver failure. In addition to these clinical signs, dynamic tests, such as indocyanine green clearance, which is available at the bed-side, are useful for the monitoring of perfusion and global liver function. In addition to specific and causal therapeutic interventions, e.g. N-acetylcysteine for paracetamol poisoning or termination of pregnancy for the HELLP-syndrome, new therapeutic measures, e.g. terlipressin/albumin or albumin dialysis are likely to improve the poor prognosis of acute-on-chronic liver failure. Nevertheless, liver transplantation remains the treatment of choice for fulminant hepatic failure when the expected survival is <20%.

Molecular adsorbents recirculating system dialysis for liver insufficiency and sepsis following right ventricular assist device after cardiac surgery

We report a case of right heart failure (RHF) and sepsis with liver insufficiency in a 70-year-old patient after coronary artery bypass graft surgery. Three hours after surgery the patient suddenly developed therapy refractory cardiac arrest caused by RHF. He had to have emergency surgery, under which the graft to the right coronary artery was revised and a right ventricular assist device was implanted. Heart function recovered and the assist device was explanted on day 1 after surgery. Thoracic closure was performed on day 5 after surgery. The patient went into septic shock on day 11. Liver dysfunction developed postoperatively and worsened the course of sepsis. Therefore, MARS (molecular adsorbents recirculating system) dialysis was performed once on day 20 after surgery. Liver function improved after MARS therapy and the patient recovered from sepsis. On day 46 the patient was transferred from the ICU of another hospital to one of the peripheral wards, to be finally discharged on day 67.