Pattern of organ failure following severe trauma

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.

Oxygenation inhibits the physiological tissue-protecting mechanism and thereby exacerbates acute inflammatory lung injury

Acute respiratory distress syndrome (ARDS) usually requires symptomatic supportive therapy by intubation and mechanical ventilation with the supplemental use of high oxygen concentrations. Although oxygen therapy represents a life-saving measure, the recent discovery of a critical tissue-protecting mechanism predicts that administration of oxygen to ARDS patients with uncontrolled pulmonary inflammation also may have dangerous side effects. Oxygenation may weaken the local tissue hypoxia-driven and adenosine A2A receptor (A2AR)-mediated anti-inflammatory mechanism and thereby further exacerbate lung injury. Here we report experiments with wild-type and adenosine A2AR-deficient mice that confirm the predicted effects of oxygen. These results also suggest the possibility of iatrogenic exacerbation of acute lung injury upon oxygen administration due to the oxygenation-associated elimination of A2AR-mediated lung tissue-protecting pathway. We show that this potential complication of clinically widely used oxygenation procedures could be completely prevented by intratracheal injection of a selective A2AR agonist to compensate for the oxygenation-related loss of the lung tissue-protecting endogenous adenosine. The identification of a major iatrogenic complication of oxygen therapy in conditions of acute lung inflammation attracts attention to the need for clinical and epidemiological studies of ARDS patients who require oxygen therapy. It is proposed that oxygen therapy in patients with ARDS and other causes of lung inflammation should be combined with anti-inflammatory measures, e.g., with inhalative application of A2AR agonists. The reported observations may also answer the long-standing question as to why the lungs are the most susceptible to inflammatory injury and why lung failure usually precedes multiple organ failure.

Bench-to-bedside review: oxygen debt and its metabolic correlates as quantifiers of the severity of hemorrhagic and post-traumatic shock

Evidence is increasing that oxygen debt and its metabolic correlates are important quantifiers of the severity of hemorrhagic and post-traumatic shock and and may serve as useful guides in the treatment of these conditions. The aim of this review is to demonstrate the similarity between experimental oxygen debt in animals and human hemorrhage/post-traumatic conditions, and to examine metabolic oxygen debt correlates, namely base deficit and lactate, as indices of shock severity and adequacy of volume resuscitation. Relevant studies in the medical literature were identified using Medline and Cochrane Library searches. Findings in both experimental animals (dog/pig) and humans suggest that oxygen debt or its metabolic correlates may be more useful quantifiers of hemorrhagic shock than estimates of blood loss, volume replacement, blood pressure, or heart rate. This is evidenced by the oxygen debt/probability of death curves for the animals, and by the consistency of lethal dose (LD)_25,50 points for base deficit across all three species. Quantifying human post-traumatic shock based on base deficit and adjusting for Glasgow Coma Scale score, prothrombin time, Injury Severity Score and age is demonstrated to be superior to anatomic injury severity alone or in combination with Trauma and Injury Severity Score. The data examined in this review indicate that estimates of oxygen debt and its metabolic correlates should be included in studies of experimental shock and in the management of patients suffering from hemorrhagic shock.

Prevention of hemorrhagic shock-induced lung injury by heme arginate treatment in rats

Hemorrhagic shock followed by resuscitation (HSR) induces oxidative stress, which leads to acute lung injury. Heme oxygenase (HO)-1 (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is inducible by oxidative stress and is thought to play an important role in the protection from oxidative tissue injuries. In this study, we examined expression of HO-1 as well as tissue injuries in the lung, liver, and kidney after HSR in rats. We also pretreated animals with heme arginate (HA), a strong inducer of HO-1, and examined its effect on the HSR-induced lung injury. HO-1 expression significantly increased in the liver and kidney following HSR, while its expression in the lung was very low and unchanged after HSR. In contrast to HO-1 expression, tissue injury and tumor necrosis factor-alpha (TNF-alpha) gene expression was more prominent in the lung compared with those in the liver and kidney. HA pretreatment markedly induced HO-1 in pulmonary epithelial cells, and ameliorated the lung injury induced by HSR as judged by the improvement of histological changes, while it decreased TNF-alpha and inducible nitric oxide synthase gene expression, lung wet weight to dry weight ratio, and myeloperoxidase activity. In contrast, inhibition of HO-1 by tin-mesoporphyrin administration abolished the beneficial effect of HA pretreatment. These findings suggest that tissues with higher HO-1 may be better protected than those with lower HO-1 from oxidative tissue injury induced by HSR. Our findings also indicate that HA pretreatment can significantly suppress the HSR-induced lung injury by virtue of its ability to induce HO-1.

The effects of surgical fracture fixation on the systemic inflammatory response to major trauma

Early stabilization of major long bone fractures is beneficial in reducing the incidence of acute respiratory distress syndrome and multiple organ failure, both of which are caused by activation of the systemic inflammatory response. This activation results in tissue recruitment of and injury by circulating polymorphonuclear leukocytes. The reasons for clinical benefits of early fracture stabilization in major trauma are unknown. Published studies indicate that fracture surgery increases the posttraumatic inflammatory response. Major surgery to stabilize fractures carries a higher complication rate when performed on patients whose hypovolemic shock is not fully corrected. Thus, fracture care should be tailored to the patient, not dictated by the injured bone. Understanding the impact of fracture surgery on the systemic inflammatory response to major trauma is necessary to refine treatment and to apply it optimally to all patients.

[Decision making and and priorities for surgical treatment during and after shock trauma room treatment]

OBJECTIVE

Concepts for optimal surgical treatment of the patient with blunt multiple injuries are being evaluated on the basis of the current literature.

METHODS

Clinical trials were systematically collected (Medline, Cochrane and hand searches) and classified into evidence levels (1 to 5 according to the Oxford system).

RESULTS

The posttraumatic clinical course is divided into four different periods: acute-, primary-, secondary- und tertiary period. The first and second period are important for life saving surgery and the stabilization of major fractures. After the cardiorespiratory systems have been stabilized, the following priorities have been formulated: head, face, spine, abdomen, extremities. To restrict the degree of operative burden on the patient it appears to be necessary to limit the duration of initial surgery to less than 6 hours. In patients at high risk to develop posttraumatic complications-"borderline patients"-it appears safer to perform only temporary fixation of major fractures.

CONCLUSIONS

Three different factors determine the clinical course after polytrauma: Trauma represents the first hit, followed by the therapy-induced burden (second hit). In addition, the third hit is represented by the individual response. An evaluation of the clinical status by immunologic monitoring can be performed in order to assess the patient's status.

Insights into the role of interleukin-6 in the induction of hepatic injury after trauma-hemorrhagic shock

Although systemic interleukin-6 (IL-6) level is elevated, hepatocellular function is impaired and liver injury occurs after trauma-hemorrhage (T-H), it remains unknown whether a causal relationship exists between elevated IL-6 levels and liver injury after T-H. We hypothesized that IL-6 is causative in the development of hepatic dysfunction and injury after T-H. To examine this, adult male Sprague-Dawley rats underwent a 5-cm midline laparotomy and were subjected to hemorrhagic shock (blood pressure = 35 mmHg for ∼90 min), followed by resuscitation (Ringer lactate, 4 times the shed blood volume). At 2, 5, and 24 h thereafter, blood samples were collected and the liver isolated and perfused for 60 min. Portal inflow pressure was measured, and perfusate samples were collected to measure IL-6, alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) levels. A significant positive correlation between plasma levels of IL-6 and ALT and perfusate levels of IL-6 and LDH levels was observed. In a second series of experiments, rats were treated with immunoglobulin G (IgG) or antibodies against rat IL-6 (anti-IL-6) at the onset of resuscitation. At 5 h after resuscitation, anti-IL-6 treatment attenuated the T-H induced increases in plasma ALT and thromboxane B2 (a thromboxane A2 metabolite) levels, and bile flow was normalized to sham levels. Perfusion of livers from normal rats with IL-6 did not alter portal pressure; however, perfusion of a stable thromboxane A2 analog dose dependently increased portal pressure. Thus IL-6 plays a significant role in the induction of hepatic dysfunction and liver injury after T-H that appears to be in part mediated by increased thromboxane A2 levels.

Perflubron emulsion improves hepatic microvascular integrity and mitochondrial redox state after hemorrhagic shock

Hemorrhagic shock is associated with decreased systemic oxygen delivery, but also with impaired microvascular perfusion, which can result in diminished local oxygen availability even in the presence of adequate cardiac output after resuscitation. Beside surgical interventions to control blood loss, transfusion of stored packed red blood cells represents the current standard of care in the management of severe hemorrhagic shock. Because stored red blood cells are less deformable and show a higher O2 affinity that affects the O2 off-load to tissues, perfluorocarbon-based artificial oxygen carriers might improve local O2 delivery under these conditions. To test this, rats were subjected to hemorrhagic shock (1 h, mean arterial pressure [MAP] 30-35 mmHg) and were resuscitated with fresh whole blood, pentastarch, stored red blood cells, perflubron emulsion (2.7 and 5.4 g/kg body weight) together with pentastarch, or stored red blood cells together with 2.7 g/kg perflubron emulsion. Hepatic microcirculation, tissue oxygenation, and mitochondrial redox state were investigated by intravital microscopy. In addition, hepatocellular function and liver enzyme release were determined. After hemorrhagic shock and resuscitation with perflubron emulsion, volumetric sinusoidal blood flow was significantly increased compared with resuscitation with stored red blood cells. Furthermore, resuscitation with perflubron emulsion resulted in higher hepatic tissue PO2 and normalized mitochondrial redox potential, which was accompanied by lessened hepatocellular injury as well as improved liver function. These results indicate that, in this model of hemorrhagic shock, asanguineous fluid resuscitation with addition of perflubron emulsion is superior to stored blood or pentastarch alone with respect to increased local O2 availability on the cellular level. This effect is primarily due to improved restoration of hepatic microcirculatory integrity.

Reduced renal expression of AQP2, p-AQP2 and AQP3 in haemorrhagic shock-induced acute renal failure

BACKGROUND

The aims of this study were to investigate the changes in the expression levels of renal aquaporins (AQPs) in response to haemorrhagic shock (HS) in rats and whether a change in the expression of AQPs was associated with parallel changes in urinary concentration.

METHODS

HS was induced by withdrawal of blood through the femoral artery in rats. A mean arterial blood pressure (MAP) of 40 mmHg was maintained for 1 h before blood was reinfused, and rats were kept in metabolic cages for urine measurements. Two days after HS, we examined the abundance of AQPs in kidney by semiquantitative immunoblotting.

RESULTS

HS rats (n = 13) developed acute renal insufficiency (creatinine clearance was 5.5 +/- 0.4 vs 6.9 +/- 0.3 ml/min/kg in sham-operated rats, n = 13, P < 0.05) and decreased urine osmolality (888 +/- 88 vs 1799 +/- 110 mosmol/kg H(2)O, P < 0.05). Consistent with this, semiquantitative immunoblotting revealed that the abundance of AQP2, phosphorylated (Ser256) AQP2 (p-AQP2) and AQP3 in whole kidney was significantly decreased after 2 days to 33 +/- 4, 41 +/- 9 and 35 +/- 14% of sham levels, respectively (P < 0.05). Also, the abundance of AQP2, p-AQP2 and AQP3 in inner medulla was markedly decreased to 36 +/- 8, 39 +/- 10 and 34 +/- 16% of sham levels (P < 0.05). In contrast, the abundance of AQP1 was not significantly changed compared with sham levels.

CONCLUSIONS

The expression of the collecting duct water channel AQP2, p-AQP2 and AQP3 was significantly downregulated after HS, which may play an important role in the impaired urinary concentrating ability in HS-induced acute renal failure.

Lung injury severity scoring in the era of lung protective mechanical ventilation: the PaO2/FIO2 ratio

BACKGROUND

Lung protective ventilatory strategies using low tidal volume and high positive end-expiratory pressure (PEEP) have become standard practice. Such strategies, however, may invalidate measurement of lung injury severity by traditional methods that are based on plain chest radiograph findings, oxygenation, minute ventilation, lung compliance, and PEEP level, such as the Murray lung injury score (LIS). Many of these criteria are potentially therapy dependent and may change with different ventilatory strategies. The purpose of this study was to determine whether measurement of lung injury severity based simply on oxygenation criteria (PaO(2)/FIO(2)) was as accurate as the Murray LIS currently used in multiple organ failure (MOF) scoring.

METHODS

Since 1992, trauma patients at high risk for developing MOF have been prospectively identified and MOF scores calculated daily. Pulmonary dysfunction is graded from 0 to 3 on the basis of a modified Murray LIS incorporating the aforementioned parameters. Lung injury severity was redefined using the PaO(2)/FIO(2) (P/F score): Grade 0 = >250; 1 = 175 to 250; 2 = 100 to 174; and 3 = <100. The maximum (worst) score using each was compared using logistic regression and receiver operating characteristic curve analysis.

RESULTS

Five hundred thirty-nine trauma patients had lung injury severity assessed using both LIS and P/F score. The mean P/F score was over twice the mean LIS (1.9 +/-.04 vs. 0.9+/-.04, p < 0.0001). In 28% of patients, the LIS and P/F score were identical, whereas in 71%, the P/F score was greater than the LIS. Both scores were significant predictors of mortality; however, receiver operating characteristic curve analysis showed that the P/F score was superior in predicting mortality (area under the curve, 0.74+/-.03 vs. 0.67+/-.04).

CONCLUSION

The P/F score is a simple method of quantifying lung injury severity in trauma patients that better predicts mortality compared with the more complicated modified Murray lung injury score currently in use. The P/F score should replace more complex and potentially therapy-dependent scores.

Relationship between injury severity and lactate levels in severely injured patients

OBJECTIVE

To determine the correlation of blood concentration of lactate and severity of injury and survival in severely injured patients.

DESIGN AND SETTING

A prospective study of severely injured patients admitted directly from an emergency surgical unit to a surgical intensive care unit with an Injury Severity Score (ISS) of 16 points or more. The study was conducted over 30 months.

PATIENTS

98 severely injured subjects aged between 16 and 82 years with ISS range from 16 to 75 points, overall 25.5% mortality.

INTERVENTIONS

Blood lactate concentrations were measured once on admission, twice daily during the first 2 days and once daily during the next 3 days. ISS, Revised Trauma Score, Shock Index, and Trauma and Injury Severity Score were calculated for each subject.

MEASUREMENTS AND RESULTS

Of 98 severely injured patients 91 had elevated blood lactate concentration (over 2.0 mmol/l). Regression analyses demonstrated that injury severity, as measured by ISS, can be predicted from lactate concentration on admission, while survival, either actual or predicted by Trauma and Injury Severity Score higher than 0.5, can be predicted from lactate concentration after 12 h. We also found that patients with Shock Index higher than 0.9 had significantly higher lactate levels during the first 36 h than those with values less than 0.9.

CONCLUSIONS

This study confirmed the relationship between blood lactate levels and injury severity as well as the prognostic value of blood lactate level for survival of severely injured patients.

Low plasma glutamine after multiple trauma: relationship with intracellular glutamine in polymorphonuclear neutrophils during prolonged ICU stay

BACKGROUND

Aim of the study was to evaluate whether low plasma glutamine (GLN) is related to low intracellular GLN in stress-affected cells such as polymorphonuclear neutrophil (PMN). We hypothesized, that because low plasma GLN is assumed to have an impact on clinical outcome, stress-affected cells may also show low GLN contents.

METHODS

Thirty-nine consecutive severely injured trauma patients staying at least 10 days at a surgical intensive care unit (ICU) of a university hospital were separated into two groups: group one (n = 16) with low plasma GLN (< 420 micromol/l in average during ICU stay), and group two (n = 23) with normal plasma GLN. Initial blood samples for GLN analyses were collected within 24 h of admission at ICU. Further blood samples were taken on days 5 and 10 at 08:00 hours.

RESULTS

Patients in both groups showed no differences regarding demographic data, surgical interventions or infections. Acute physiology and chronic health evaluation (APACHE) II and the sequential organ failure assessment (SOFA) score and mortality rate were also comparable. During the study period, intracellular PMN GLN contents and concentrations did not differ between both groups. On the first day, intracellular PMN GLN content in the low plasma GLN group peaked at 5.01 +/- 3.06 x 10(-16) mol and in normal plasma GLN group at 4.73 +/- 2.57 x 10(-16) mol above the level of healthy individuals. In both groups, content decreased significantly towards the end of the observation period (group one: 2.79 +/- 1.59 x 10(-16) mol and group two: 2.63 +/- 1.71 x 10(-16) mol). A correspondent course could be observed for cell volumes. In contrast, variation of intracellular GLN concentrations remained within the reference range throughout the observation period: group one 836 +/- 510 micromol/l on day 1 and 582 +/- 331 micromol/l on day 10, and group two 788 +/- 428 micromol/l on day 1 and 548 +/- 356 micromol/l on day 10. No correlation between plasma GLN and intracellular GLN was found in either group.

CONCLUSION

No association between low plasma GLN and low intracellular GLN in PMN was found in a cohort of severely injured trauma patients with a minimum stay of 10 days at ICU.

Recovery of hepatocellular ATP and "pericentral apoptosis" after hemorrhage and resuscitation

Progressive liver dysfunction contributes significantly to the development of multiple organ failure after trauma/hemorrhage. This study tested the relative impact of necrotic and apoptotic cell death in a graded model of hemorrhagic shock (mean arterial blood pressure=35+/-5 mmHg for 1, 2, or 3 h, followed by 2 h, 1 h, or no resuscitation, respectively) in rats. Prolonged periods of hemorrhagic hypotension (3 h) were paralleled by a profound decrease of hepatic ATP levels and occurrence of pericentral necrosis. Resuscitation after shorter periods of hemorrhagic hypotension resulted in restoration of tissue ATP whereas hepatocellular function as assessed by indocyanine green clearance remained depressed (49.9+/-1.6 mL/(min x kg) at baseline, 28.8+/-1.2 mL/(min x kg) after 2 h of resuscitation; P<0.05). Under these conditions, induction of caspase activity and DNA fragmentation were observed in pericentral hepatocytes that could be prevented by the radical scavenger tempol. Pretreatment with z-Val-Ala-Asp(O-methyl)-flouromethylketone prevented de novo expression of caspase-generated cytokeratin 18, DNA fragmentation, and depression of hepatocellular indocyanine green clearance. These data suggest that prolonged low flow/hypoxia induces ATP depletion and pericentral necrosis and restoration of oxygen supply and ATP levels after shorter periods of low flow ischemia propagate programmed cell death or "pericentral apoptosis."

The injured child is resistant to multiple organ failure: a different inflammatory response?

BACKGROUND

Although postinjury multiple organ failure (MOF) is a well-described phenomenon in adults, the incidence of this syndrome in children is unknown. The purpose of this study was to describe the incidence, course, and severity of pediatric postinjury MOF. We hypothesized that the incidence and severity of postinjury MOF in children would be less when compared with adults.

METHODS

Patients were retrospectively identified from the trauma registry of a regional pediatric trauma center and an adult Level I trauma center with pediatric commitment for a 3-year period. All trauma patients less than 16 years old who survived for longer than 24 hours and had an Injury Severity Score > 15 were eligible. An accepted MOF score was used. Categorical variables were compared by chi2 and continuous variables by t test. A value of p< 0.05 was considered statistically significant.

RESULTS

Of 534 patients identified, 334 (63%) were admitted for evaluation of isolated head injury and excluded from further analysis. The rate of postinjury MOF in children was found to be only 3%, with a low (17%) mortality when compared with historical adult data (50%).

CONCLUSION

The incidence of postinjury MOF in the child is less than in the adult, given equivalent injury severity. These observations solidify the contention that postinjury MOF is rare in children, and is less severe when it occurs. Delineating the mechanism(s) whereby children are protected from postinjury MOF may provide insight into the development of strategies to prevent MOF in other age groups as well as various disease states.

Polymicrobial sepsis induces organ changes due to granulocyte adhesion in a murine two hit model of trauma

INTRODUCTION

Polytrauma patients, who develop organ dysfunction, have often undergone multiple subsequent insults ("hits"). The sequence of organs that show a dysfunction mostly is lung, liver, kidney and heart. The aim of the present study was to investigate whether a second hit after trauma induces organ changes. Furthermore, it was of interest to identify possible pathogenic mediators such as polymorphonuclear granulocytes (PMN) and cytokines. For this purpose, a two hit model of systemic damage in mice was developed. Sepsis was induced by caecal ligation and puncture (CLP), which was preceded 48 hours by a femur fracture, the most common fracture of long bones in trauma patients. This fracture was combined with a haemorrhagic shock.

METHODS

In both mouse groups studied, a standardized femur fracture was produced using a blunt guillotine device with a weight of 500 g. This was followed by a haemorrhagic shock with substitution of ringer's lactate after 1 hour. In the study group, CLP was induced by puncturing the caecum using a 21G needle. As a control, sham animals underwent a laparotomy without CLP. Both groups were sacrificed after 48 or 96 hours. Clinical parameters were investigated on a daily basis to evaluate the animals' status. Lung, liver and kidney morphology was studied by light microscopy. PMN adhesion was determined by counting the number of adherent PMN per 100 microm of endothelium. Serum levels of TNF-alpha were measured after 48 and 96 hours.

RESULTS

In the group submitted to laparotomy, all animals survived. The induction of polymicrobial sepsis by CLP resulted in an 85% (34/40) mortality within 96 hours after surgery (p < 0.05). The induction of a polymicrobial sepsis resulted in a significantly steady worsening of the clinical situation compared to the sham animals (p < 0.05). Lung morphology demonstrated significant changes at the end of the experimental period after 96 h in the two hit group. The alveolar septa were thickened and in all lungs haemorrhagic foci were observed. The number of PMN adhering to the pulmonary endothelium significantly increased at 96 hours. Some of the liver specimens in the two hit group showed focal hydropic degeneration and PMN infiltration. No kidney pathology was observed. This result coincided with an increase in TNF-alpha serum levels.

DISCUSSION

A new rodent model mimicking the situation in the polytraumatized patient was developed. Although the animals showed minimal organ manifestation, a high percentage died probably due to cytokinemia. Furthermore, the increased TNF-alpha levels may lead to increased adhesion of PMN in the lung venules. This adhesion developed four days after the second hit. This might be the initial step for the development of extensive lung lesions in later phases. This model represents the SIRS more than MODS. This is a model for devolopment of posttraumatic disease due to cytokinemia and less for chronic multiple organ dysfunction and failure.

Heme oxygenase-1: redox regulation and role in the hepatic response to oxidative stress

Heme oxygenase (HO) catalyzes the oxidative cleavage of the alpha-mesocarbon of Fe-protoporphyrin-IX yielding equimolar amounts of biliverdin-IXalpha, free divalent iron, and carbon monoxide (CO). Among the three isoenzymes cloned to date, only HO-1 can be induced by a variety of seemingly disparate stimuli, most of which are linked by their ability to provoke oxidative stress. Although constitutive expression of HO-1 in the liver is restricted to Kupffer cells, the gene is inducible in nonparenchymal as well as in parenchymal liver cells. HO-1 induction potentially confers protection against oxidative stress in a variety of experimental models, such as liver ischemia/reperfusion secondary to transplantation or hemorrhage/resuscitation. Induction of HO-1 may protect the cell against oxidative injury by (a) controlling intracellular levels of "free" heme (a prooxidant), (b) producing biliverdin (an antioxidant), (c) improving nutritive perfusion via CO release, and (d) fostering the synthesis of the Fe-binding protein ferritin. Although protective effects of up-regulation of the HO pathway--presumably through production of bile pigments and CO--have been reported for a variety of cells and tissues, including the liver, evidence suggests that the protective action might be restricted to a rather narrow threshold of overexpression. High levels of HO-1 may even sensitize the cell to oxidative stress, e.g., through release of reactive iron. Transcriptional activation of the HO-1 gene is an integral part of the cellular response to oxidative stress, but its induction seems to be neither exclusively cytoprotective nor exclusively cytotoxic.

Hepatic redox regulation of transcription factors activator protein-1 and nuclear factor-kappaB after hemorrhagic shock in vivo

Ischemia and reperfusion result in a hepatocellular stress gene response, characterized by a zonal heterogeneity with pericentral hepatocytes being the primary target. In the present study, we assessed cell type-specific and zonal pattern of activation of redox-sensitive transcription factors nuclear factor-kappaB (NFkappaB) and activator protein-1 (AP-1) in a graded model of hemorrhage and their modulation by the antioxidants trolox and tempol. Hemorrhagic hypotension (35-40 mm Hg) up to 3 h without subsequent resuscitation led to an only moderate activation of NFkappaB and AP-1. In contrast, fluid resuscitation after 1 or 2 h of hemorrhage induced a profound activation of AP-1 within the first hour of reperfusion. Consistent with a regulation by oxygen free radicals, activation of AP-1 was substantially attenuated by antioxidants. The faint activation of NFkappaB with various intervals of hemorrhage was unaffected by antioxidants and did not exceed activation with sham operation. Immunohistochemistry for the AP-1 subunit c-Jun revealed a predominant expression in nuclei of pericentral and midzonal hepatocytes. These data suggest activation of AP-1 in hepatocytes most susceptible to injury and reprogramming of gene expression in low-flow ischemia. Whereas activation of NFkappaB is weak in this model and is not modulated by either reperfusion or antioxidants, regulation of AP-1 after hemorrhage and subsequent resuscitation seems to depend on oxygen free radical formation because it requires reperfusion and is inhibitable by antioxidants.

Hepatic dysfunction increases length of stay and risk of death after injury

BACKGROUND

The relative importance of dysfunction or failure of different organ systems to recovery from critical illness is unclear. The purpose of this study was to evaluate the contribution of hepatic dysfunction to outcome after injury.

METHODS

We retrospectively evaluated patients admitted to our trauma center from 1994 to 1998 for the development of hepatic dysfunction, defined as serum bilirubin > or = 2.0 mg/dL. Additional variables on patient demographics, injuries, hospital course, and development of other organ system dysfunction were collected from the trauma registry and hospital records.

RESULTS

Using logistic regression analysis, hepatic dysfunction was significantly associated with increased intensive care unit length of stay (LOS) and death. The added development of hepatic dysfunction significantly increased LOS in patients with no other organ dysfunction, those with renal dysfunction, and those with respiratory dysfunction.

CONCLUSION

Hepatic dysfunction influences recovery after injury independent of the dysfunction of other organ systems. The development of hepatic dysfunction prolongs LOS and increases mortality.

Increased neutrophil migratory activity after major trauma: a factor in the etiology of acute respiratory distress syndrome?

OBJECTIVE

Neutrophil infiltration of the lung is characteristic of early posttraumatic acute respiratory distress syndrome (ARDS). This study examines the ability of neutrophils isolated (over the first 24 hrs) from the peripheral blood of patients admitted after major trauma to migrate in response to interleukin-8. Interleukin-8 is elevated in the lung within 2 hrs of major trauma in patients who later develop ARDS, and thus it plays a central role in the recruitment of neutrophils to the lung and their subsequent activation. We hypothesized that enhanced interleukin-8-mediated neutrophil migratory activity in the early postinjury phase, before the development of ARDS, may be a crucial factor in the etiology of ARDS.

DESIGN

Prospective observational study.

SETTING

University Hospital Wales, the Royal Gwent Hospital, and East Glamorgan General Hospital. Laboratory work was conducted at the Institute of Nephrology.

PATIENTS

Adult blunt trauma victims with Injury Severity Score > or = 18.

MEASUREMENTS AND MAIN RESULTS

Neutrophils were isolated from citrated blood from 17 adult blunt major trauma patients at admission (0 hrs) and 8 and 24 hrs later. Identical samples were obtained from normal laboratory volunteers (n = 9). The neutrophil count in each specimen was measured, and the number of neutrophils migrating across porous tissue culture inserts in response to defined concentrations of interleukin-8 (0, 10, 30, and 100 ng/mL) was quantitated by peroxidase assay. Neutrophil counts in the whole blood specimens obtained from those later developing ARDS were elevated significantly at admission and declined rapidly throughout the next 24 hrs. Significantly greater numbers of trauma patients' neutrophils migrated to concentrations of interleukin-8 (30 and 100 ng/mL) at each time point when compared with normal volunteers (Mann-Whitney U test, p <.05). Neutrophils isolated from major trauma patients exhibited an enhanced migratory response to high concentrations of interleukin-8 throughout the first 24 hrs of admission, in contrast to the normal physiologic attenuation of migration seen in neutrophils isolated from normal laboratory volunteers.

CONCLUSIONS

These data indicate that major blunt trauma enhances the migratory capacity of circulating neutrophils. This is manifest within 2 hrs of admission and may be attributable to alteration in interleukin-8 receptor expression, affinity, or downstream signaling. In patients who later develop ARDS, initially elevated circulating neutrophil counts decrease rapidly, over the same time course. Early enhanced neutrophil migratory activity coupled with elevated pulmonary concentrations of interleukin-8 may be central to the establishment of the neutrophil infiltration that is characteristic of ARDS.

Early treatment with lexipafant, a platelet-activating factor-receptor antagonist, is not sufficient to prevent pulmonary endothelial damage after intestinal ischaemia and reperfusion in rats

BACKGROUND

Intestinal ischaemia-reperfusion can lead to pulmonary injury characterised by increased macromolecular leakage and leukocyte sequestration. Important mediators of ischaemia-reperfusion-associated injury include polymorphonuclear granulocytes and platelet-activating factor.

AIM

To investigate the potential therapeutic inhibition of platelet-activating factor in intestinal ischaemia-reperfusion associated pulmonary injury, by use of a potent platelet-activating factor-receptor antagonist, lexipafant.

METHODS

Rats were subjected to 30 minutes of intestinal ischaemia followed by 3 or 12 hours reperfusion. Lexipafant or saline was given intraperitoneally after 30 minutes reperfusion.

RESULTS

Increased leakage of radiolabelled human serum albumin was found in the lungs after intestinal ischaemia followed by 3 or 12 hours reperfusion. Administration of lexipafant did not significantly prevent the increased leakage. Pulmonary myeloperoxidase content increased after intestinal ischaemia-reperfusion, indicating polymorphonuclear granulocyte sequestration through the pulmonary endothelium. The increase in interleukin-1beta seen after 3 hours reperfusion was partly reversed by lexipafant.

CONCLUSIONS

Pulmonary injury occurred following intestinal ischaemia-reperfusion, characterised by increased leakage of radiolabelled albumin over the endothelial barrier; correlating with increased pulmonary myeloperoxidase-content, implying involvement of polymorphonuclear granulocytes in the pathogenesis of remote organ injury after intestinal ischaemia-reperfusion. Lexipafant did not significantly decrease severity of pulmonary damage.

Current controversies in shock and resuscitation

Many controversies and uncertainties surround resuscitation of hemorrhagic shock caused by vascular trauma. Whereas the basic pathophysiology is better understood, much remains to be learned about the many immunologic cascades that lead to problems beyond those of initial fluid resuscitation or operative hemostasis. Fluid therapy is on the verge of significant advances with substitute oxygen carriers, yet surgeons are still beset with questions of how much and what type of initial fluid to provide. Finally, the parameters chosen to guide therapy and the methods used to monitor patients present other interesting issues.

Multiple organ failure still a major cause of morbidity but not mortality in blunt multiple trauma

BACKGROUND

Multiple organ failure (OF/MOF) was found to be the major complication after blunt multiple trauma during the last 25 years and was correlated with a high mortality rate. Recently, several publications reported a decreased ARDS-related mortality, but there is little information about mortality rates from posttraumatic MOF. The purpose of this study was to describe the development of MOF-related death after blunt multiple trauma during the last 25 years.

METHODS

Blunt multiple trauma patients with an Injury Severity Score (ISS) > 15 points were included in this evaluation. According to the year of trauma, the population was divided into five groups: years 1975-1980 (n = 317), years 1981-1985 (n = 308), years 1986-1990 (n = 246), years 1991-1997 (n = 368), and years 1998-1999 (n = 122). Main outcome measurements were death, cause of death, and length of ICU stay. Patients dying within the first 24 hours after trauma were excluded. All data indicated in the Results section are presented as mean +/- SEM. Continuous variables were compared by ANOVA. Ordinal variables were analyzed by chi2 contingency table analysis and, if significant, subsequently by Fisher's exact test (two-tailed test, p < 0.05).

RESULTS

Mean ISS remained unchanged between 1975-1980 (ISS 29 +/- 1) and 1998-1999 (ISS 31 +/- 1) (p = 0.56). During the observation period, the mean age increased from 33 +/- 1 years (1975-1980) to 40 +/- 2 years (1998-1999) (p = 0.03). The overall incidence of OF/MOF slightly increased from 25.6% (1975-1980) to 33.6% (1998-1999) (p = 0.1). Length of ICU stay was not different between 1975-1980 (LOS: 14 +/- 1 d) and 1998-1999 (LOS: 19 +/- 2 d) (p = 1.0). The overall mortality decreased significantly, from 28.7% (1975-1980) to 13.9% (1998-1999) (p < 0.001). While the mortality due to severe head injuries remained unchanged (1975-1980, 8.2%; 1998-1999, 9.0%) (p = 0.85), mortality due to OF/MOF decreased significantly (p < 0.001), from 18.0% (1975-1980) to 4.1% (1998-1999). The age of patients dying from OF/MOF increased significantly (p = 0.04) during the observation period, from 44 +/- 3 years (1975-1980) to 63 +/- 6 years (1998-1999).

CONCLUSION

Although MOF incidence remains unchanged, there is a significant fall in MOF-related mortality in patients with severe trauma, and death from single organ failure is virtually absent. Severe brain injury is now the leading cause of death in patients with severe multiple injuries admitted to the ICU.

Differential activation pattern of redox-sensitive transcription factors and stress-inducible dilator systems heme oxygenase-1 and inducible nitric oxide synthase in hemorrhagic and endotoxic shock

OBJECTIVE

To investigate the role of redox-sensitive transcription factors nuclear factor kappa-B (NF-kappaB) or activator protein-1 (AP-1) for hepatic gene expression of heme oxygenase (HO)-1 and inducible nitric oxide synthase (iNOS) in models of hemorrhagic or endotoxic shock.

DESIGN

Prospective controlled laboratory study.

SETTING

Animal research laboratory at a university hospital.

SUBJECTS

Male Sprague-Dawley rats (250-350 g).

INTERVENTIONS

After anesthesia, animals were assigned to hemorrhagic shock (mean arterial pressure 35-40 mm Hg for 60 mins), sham operation, or endotoxemia (1 mg/kg intraperitoneally). To assess the role of reactive oxygen species for activation of NF-kappaB or AP-1, animals were treated with the antioxidant trolox (6 mg/kg body weight). In additional experiments, animals were pretreated with dexamethasone (10 mg/kg body weight), an inhibitor of the transactivating function of DNA-bound AP-1 or with actinomycin-D (2 mg/kg body weight), an inhibitor of DNA-directed RNA synthesis. Activation of NF-kappaB or AP-1 was assessed by electrophoretic mobility shift assay. HO-1 and iNOS gene expression were assessed by Northern and Western blot.

MEASUREMENTS AND MAIN RESULTS

Hemorrhage and resuscitation induced hepatic HO-1 transcripts 12-fold. Induction was abolished by actinomycin-D and was attenuated by dexamethasone and the antioxidant trolox. Activation of AP-1 was observed after hemorrhagic but not after endotoxic shock. AP-1 activation was inhibitable by trolox and correlated with accumulation of HO-1 transcripts. In contrast, a weak activation of NF-kappaB was observed after hemorrhage that was not affected by trolox. A profound activation of NF-kappaB after endotoxic shock correlated with induction of iNOS but failed to induce HO-1 transcripts.

CONCLUSIONS

These data suggest that AP-1 but not NF-kappaB activation is dependent on reactive oxygen intermediates in vivo and contributes to HO-1 gene expression. Thus, AP-1-dependent HO-1 induction under oxidative stress conditions may subserve a similar function as a stress-inducible vasodilator system as does NF-kappaB-dependent iNOS expression in liver inflammation.

Hemorrhagic shock primes the hepatic portal circulation for the vasoconstrictive effects of endothelin-1

To test whether hemorrhagic shock and resuscitation (HSR) alters the vascular responsiveness of the portohepatic circulation to endothelins (ETs), we studied the macro- and microcirculatory effects of the preferential ET(A) receptor agonist ET-1 and of the selective ET(B) receptor agonist sarafotoxin 6c (S6c) after 1 h of hemorrhagic hypotension and 5 h of volume resuscitation in the isolated perfused rat liver ex vivo using portal pressure-flow relationships and epifluorescence microscopy. Although HSR did not cause major disturbances of hepatic perfusion per se, the response to ET-1 (0.5 x 10(-9) M) was enhanced, leading to greater increases in portal driving pressure, total portal resistance, and zero-flow pressures and more pronounced decreases in portal flow, sinusoidal diameters, and hepatic oxygen delivery compared with time-matched sham shock controls. In sharp contrast, the constrictive response to S6c (0.25 x 10(-9) M) remained unchanged. Thus HSR primes the portohepatic circulation for the vasoconstrictive effects of ET-1 but does not alter the effects of the ET(B) receptor agonist S6c. The enhanced sinusoidal response may contribute to the subsequent development of hepatic microcirculatory failure after secondary insults that are associated with increased generation of ET-1.

High density lipoproteins reduce organ injury and organ dysfunction in a rat model of hemorrhagic shock

High density lipoproteins (HDLs) inhibit the cytokine-induced expression of endothelial cell adhesion molecules both in vitro and in vivo. We examined the ability of HDLs to mediate a functional anti-inflammatory effect by measuring their ability to prevent neutrophil adhesion and transmigration in vitro. Treatment of human endothelial cell cultures with physiologic concentrations of HDLs inhibited neutrophil binding by 68 +/- 5.9% (mean and se, n=6, P<0.05) and neutrophil transmigration by 48.7 +/- 6.7% (n=8, P<0.05). We then examined the effect of HDLs on inflammatory infiltration and subsequent multiple organ dysfunction syndrome (MODS), associated with trauma in a rat model of hemorrhagic shock. Rats given human HDLs (80 mg apo A-I/kg, i.v.) 90 min after hemorrhage (which reduced mean arterial pressure to 50 mmHg) and 1 min before resuscitation showed attenuation of the increases in the serum levels of markers of MODS normally observed in this model. Severe disruption of the architecture of tissues and the extensive cellular infiltration into those tissues were also largely inhibited in animals that received HDLs. Human HDLs attenuate the MODS associated with ischemia and reperfusion injury after hemorrhagic shock in rats.

Survival rate after early treatment for acute type-A aortic dissection with ACTH-(1-24)

Haemorrhagic shock, usually as a consequence of major trauma, is the most frequent cause of death among people younger than 40 years. Reports indicate that melanocortin peptides are effective in reversing haemorrhagic shock. We found that in patients with aortic-dissection-induced haemorrhagic shock, the addition of an early intravenous bolus injection of the melanocortin andrenocorticotrophic hormone (ACTH)-(1-24) to standard treatment significantly improved cardiovascular function and increased survival rate. Because administration of ACTH-(1-24) is simple, and because melanocortin peptides have no acute toxicity, their use in the early critical care of patients in shock should be more extensively assessed.

TNF-α increases sensitivity to LPS in chronically catheterized rats

Patients with severe trauma injury are transiently exposed to increased serum concentrations of tumor necrosis factor-α (TNF-α). These patients are susceptible to the development of multisystem organ failure (MSOF) triggered by subsequent exposure to bacterial toxins either via infection or increased intestinal permeability. We simulated the cytokine response of trauma by infusing 0.8 or 8.0 μg/kg of TNF-α (priming dose) into chronically catheterized rats. After 48 h, rats were challenged with endotoxin [lipopolysaccharide (LPS); 10 or 1,000 μg/kg]. Animals primed with either dose of TNF-α and then challenged with 1,000 μg/kg of LPS demonstrated significantly increased mortality, mean peak serum concentrations of interferon-γ (IFN-γ), and blood lactate concentrations ( P < 0.05) compared with nonprimed animals. Mean peak serum concentrations of IFN-γ and blood lactate concentrations were increased after challenge with 10 μg/kg of LPS only in animals primed with 8.0 μg/kg of TNF-α. Priming with TNF-α did not increase mortality after challenge with 10 μg/kg of LPS. These data suggest that both TNF-α release and the subsequent exposure to bacterial toxins mediate the pathophysiological progression from trauma to subsequent MSOF.

Compensatory hepatic regeneration after mild, but not fulminant, intraperitoneal sepsis in rats

Sepsis is the leading cause of death in surgical intensive care units. Although both mild sepsis secondary to cecal ligation and single puncture (CLP) and fulminant, double puncture CLP (2CLP) may provoke hepatocyte death, we hypothesize that regeneration compensates for cell death after CLP but not 2CLP. In male Sprague-Dawley rats, hepatic necrosis, as determined by serum alpha-glutathione S-transferase (alpha-GST) levels, was significantly but equally elevated over time after both CLP and 2CLP. Apoptosis, evaluated using both terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and morphological examination, was minimal after both CLP and 2CLP. Regeneration, assayed by staining tissue for incorporation of exogenously administered bromodeoxyuridine, was present after CLP but not after 2CLP. To further substantiate impaired regeneration, steady-state levels of mRNAs encoding JunB, LRF-1, and cyclin D1 were determined. After 2CLP, the absence of JunB, LRF-1, and cyclin D1 mRNAs confirmed failed activation of the mitogen-activated protein kinase-linked proliferative pathway and progression through the cell cycle. Therefore, failed hepatocyte regeneration may be a manifestation of hepatic dysfunction in fulminant sepsis.

Calpain inhibitor I reduces the activation of nuclear factor-kappaB and organ injury/dysfunction in hemorrhagic shock

There is limited evidence that inhibition of the activity of the cytosolic cysteine protease calpain reduces ischemia/reperfusion injury. The multiple organ injury associated with hemorrhagic shock is due at least in part to ischemia (during hemorrhage) and reperfusion (during resuscitation) of target organs. Here we investigate the effects of calpain inhibitor I on the organ injury (kidney, liver, pancreas, lung, intestine) and dysfunction (kidney) associated with hemorrhagic shock in the anesthetized rat. Hemorrhage and resuscitation with shed blood resulted in an increase in calpain activity (heart), activation of NF-kappaB (kidney), expression of iNOS and COX-2 (kidney), and the development of multiple organ injury and dysfunction, all of which were attenuated by calpain inhibitor I (10 mg/kg i.p.), administered 30 min prior to hemorrhage. Chymostatin, a serine protease inhibitor that does not prevent the activation of NF-kappaB, had no effect on the organ injury/failure caused by hemorrhagic shock. Pretreatment (for 1 h) of murine macrophages or rat aortic smooth muscle cells (activated with endotoxin) with calpain inhibitor I attenuated the binding of activated NF-kappaB to DNA and the degradation of IkappaBalpha, IkappaBbeta, and IkappaBvarepsilon. Selective inhibition of iNOS activity with L-NIL reduced the circulatory failure and liver injury, while selective inhibition of COX-2 activity with SC58635 reduced the renal dysfunction and liver injury caused by hemorrhagic shock. Thus, we provide evidence that the mechanisms by which calpain inhibitor I reduces the circulatory failure as well as the organ injury and dysfunction in hemorrhagic shock include 1) inhibition of calpain activity, 2) inhibition of the activation of NF-kappaB and thus prevention of the expression of NFkappaB-dependent genes, 3) prevention of the expression of iNOS, and 4) prevention of the expression of COX-2. Inhibition of calpain activity may represent a novel therapeutic approach for the therapy of hemorrhagic shock.

Hemodynamic tolerance of intermittent hemodialysis in critically ill patients: usefulness of practice guidelines

Poor hemodynamic tolerance of intermittent hemodialysis (IHD) is a common problem for patients in an intensive care unit (ICU). New dialysis strategies have been adapted to chronic hemodialysis patients with cardiovascular insufficiency. To improve hemodynamic tolerance of IHD, specific guidelines were progressively implemented into practice through the year 1996 in our 26-bed medical ICU. To evaluate the efficiency of these guidelines we retrospectively compared all IHD performed during the years before (1995) and after (1997) implementation of these recommendations. Forty-five patients underwent 248 IHD sessions in 1995 and 76 patients underwent 289 IHD sessions in 1997. The two populations were similar for age, sex, chronic hemodialysis (26% versus 17%), and secondary acute renal failure. In 1997, patients were more severely ill with a higher SAPS II (50 +/- 17 versus 59 +/- 24; p = 0.036), and more patients required epinephrine or norepinephrine infusion before dialysis sessions (16% versus 34%; p < 0.0001). The compliance to guidelines was high, inducing a significant change in IHD modalities. As a result, hemodynamic tolerance was significantly better in 1997, with less systolic blood pressure drop at onset (33% versus 21%, p = 0. 002) and during the sessions (68% versus 56%, p = 0.002). IHD with hypotensive episode or need for therapeutic interventions were less frequent in 1997 (71% versus 61%, p = 0.015). The ICU mortality was similar (53.3% in 1995 versus 47.3% in 1997; p = 0.52) but death rate in 1997, but not in 1995, was significantly less than predicted from SAPS II (47.3% versus 65.6%; p = 0.02). Length of ICU stay was also reduced for survivors in 1997 (p = 0.04). Implementation of practice guidelines for intermittent hemodialysis in ICU patients lessens hemodynamic instability and may improve outcome.

Inflammatory responses and mediators

The host response to injury is usually appropriate in degree and is self-limited. In more severe injury, the host response may persist inappropriately, leading to SIRS and MODS and possibly multiple organ failure. The initial response to injury is mediated primarily by norepinephrine, and is directed toward preservation of circulation to the heart and brain at the expense of other vascular beds. If fluid resuscitation is adequate and necrotic tissue is débrided, a hypermetabolic state ensues, mediated by epinephrine and directed toward supporting repair of injured tissue by leukocytes. Inflammatory cells are recruited to the site of injury and elaborate cytokines, which promote repair locally, but in severe injury may be systemically released and trigger remote inflammation. Cytokine biology presently is poorly understood, and simple anticytokine strategies have failed to improve survival of critically ill patients. Current therapy of SIRS and MODS is directed toward symptoms. Presently, it is unclear how an abnormal stress response arises. Cytokine spillover into the systemic circulation may occur. Selective transcriptional failure may be the cellular basis of organ dysfunction. Inappropriate production of peroxynitrite or its precursor, NO, is implicated in mediating cellular injury in SIRS and MODS.

Inhibition of neutrophil apoptosis after severe trauma is NFkappabeta dependent

BACKGROUND

Systemic inflammation may inhibit neutrophil (PMN) apoptosis and promote multiple organ dysfunction syndrome. We hypothesize that severe trauma causes dysregulation of PMN apoptosis.

METHODS

Neutrophils were isolated from trauma patients (24-72 hours after injury; n = 16) and controls (healthy volunteers) and incubated for 18 hours. In separate experiments, control cells were treated +/- the nuclear factor kappa beta (NFkappabeta) inhibitor pyrrolidinithiocarbamate then incubated with 25% patient or control plasma. Apoptosis was quantified by enzyme-linked immunosorbent assay for histone-associated DNA and annexin V fluorescence-activated cell sorter. NFkappabeta activation was determined by Western blot for phosphorylated I kappabeta.

RESULTS

Apoptosis was inhibited in trauma patient PMN. Neutrophil apoptosis correlated with multiple organ dysfunction syndrome score, Acute Physiology and Chronic Health Evaluation II, and platelet count. Patient plasma inhibited apoptosis and induced phosphorylation of I kappabeta in control cells. Inhibition of PMN apoptosis by patient plasma was blocked by pretreatment with pyrrolidinithiocarbamate.

CONCLUSION

NFkappabeta-dependent inhibition of neutrophil apoptosis occurs after trauma. Early inhibition of PMN apoptosis is dependent on the magnitude of injury.

Pathogenesis and management of multiple organ dysfunction or failure in severe sepsis and septic shock

Organ system dysfunction is a common adverse sequelae of severe sepsis and septic shock and has been reported to be the most common cause of death in the noncoronary intensive care unit. The pathophysiology of the development of multiple organ system dysfunction is likely multifactoral and may take several different pathways. The frequency of specific organ system involvement is dependent on the definition used to describe the organ dysfunction. The presence of organ dysfunction has great clinical impact on the underlying disease process, can prolong the hospital stay, increase the cost of care, and has been associated with an increase in mortality rate. At present, there is no recognized specific treatment for established organ failure, this primary attention has been directed toward prevention.

Development of a percutaneous fiberoptic hepatic venous localization catheter

OBJECTIVE

To develop a liver-specific biosensor system/catheter assembly that can be used to localize and cannulate the hepatic venous system without the need for fluoroscopic imaging. This would permit the bedside placement of a hepatic venous catheter for monitoring purposes without radiographic guidance.

DESIGN

Experimental, in vitro.

STUDY SETTING

Experimental laboratory at a university center.

SUBJECT

This was a simulation study to evaluate the ability of a cardiovascular monitoring catheter mounted with a liver-specific biosensor to anatomically identify a side arm tributary. The experimental system used for this study mimics the hepatic vein draining into the inferior vena cava and allows its localization without the need for assisted imaging. The biosensor design and catheter/sensor assembly function were studied in this in vitro model.

INTERVENTIONS

A liver-specific biosensor was developed by housing a homogeneous affinity fluorescence assay system sensitive to galactose in a microdialysis hollow fiber receptacle. A polyvinyl chloride tube containing a side arm was constructed to mimic the confluence of a venous tributary (i.e., the hepatic vein) with a major vascular channel (i.e., the vena cava). In this simulation, the side arm was continuously perfused with a liver-sensitive analyte (galactose) and the main channel was perfused with galactose-free buffer. A cardiovascular catheter containing a fiberoptic waveguide mounted with a galactose-sensitive fluorescent probe was advanced along the main conduit to assess its ability to identify the location of the galactose side arm infusion site.

MEASUREMENTS AND MAIN RESULTS

The response of the fiberoptic sensor to different galactose concentrations was assessed and found to be almost linear over the concentration range of 0 to 2 mM, which encompasses the expected utilization range of this system. The variability in identifying the galactose infusion point (simulated hepatic vein) in a 15-cm conduit was 1.7 to 2.8 mm, or 1.1% to 1.9%.

CONCLUSIONS

The construction of a catheter/sensor system with the ability to provide accurate spatial/anatomical localization data for the hepatic venous system is feasible. This assembly will eliminate the need for ancillary imaging systems for catheter/sensor delivery to an individual organ system and potentially can be positioned at the bedside in a fashion similar to the pulmonary artery flotation catheter.

Analysis of the effect of conversion from open to closed surgical intensive care unit

OBJECTIVE

To compare the effect on clinical outcome of changing a surgical intensive care unit from an open to a closed unit.

DESIGN

The study was carried out at a surgical intensive care unit in a large tertiary care hospital, which was changed on January 1, 1996, from an open unit, where private attending physicians contributed and controlled the care of their patients, to a closed unit, where patients' medical care was provided only by the surgical critical care team (ABS or ABA board-certified intensivists). A retrospective review was undertaken over 6 consecutive months in each system, encompassing 274 patients (125 in the open-unit period, 149 in the closed-unit period). Morbidity and mortality were compared between the two periods, along with length-of-stay (LOS) and number of consults obtained. A set of independent variables was also evaluated, including age, gender, APACHE III scores, the presence of preexisting medical conditions, the use of invasive monitoring (Swan-Ganz catheters, central and arterial lines), and the use of antibiotics, low-dose dopamine (LDD) for renal protection, vasopressors, TPN, and enteral feeding.

RESULTS

Mortality (14.4% vs. 6.04%, p = 0.012) and the overall complication rate (55.84% vs. 44.14%, p = 0.002) were higher in the open-unit group versus the closed-unit group, respectively. The number of consults obtained was decreased (0.6 vs. 0.4 per patient, p = 0.036), and the rate of occurrence of renal failure was higher in the open-unit group (12.8% vs. 2.67%, p = 0.001). The mean age of the patients was similar in both groups (66.48 years vs. 66.40, p = 0.96). APACHE III scores were slightly higher in the open-unit group but did not reach statistical significance (39.02 vs. 36.16, p = 0.222). There were more men in the first group (63.2% vs. 51.3%). The use of Swan-Ganz catheters or central and arterial lines were identical, as was the use of antibiotics, TPN, and enteral feedings. The use of LDD was higher in the first group, but the LOS was identical.

CONCLUSIONS

Conversion of a tertiary care surgical intensive care unit from an open to closed environment reduced dopamine usage and overall complication and mortality rates. These results support the concept that, when possible, patients in surgical intensive care units should be managed by board-certified intensivists in a closed environment.

Intrahepatic STAT-3 activation and acute phase gene expression predict outcome after CLP sepsis in the rat

Interleukin-6 (IL-6) regulates hepatic acute phase responses by activating the transcription factor signal transducer and activator of transcription (STAT)-3. IL-6 also may modulate septic pathophysiology. We hypothesize that 1) STAT-3 activation and transcription of alpha2-macroglobulin (A2M) correlate with recovery from sepsis and 2) STAT-3 activation and A2M transcription reflect intrahepatic and not serum IL-6. Nonlethal sepsis was induced in rats by single puncture cecal ligation and puncture (CLP) and lethal sepsis via double-puncture CLP. STAT-3 activation and A2M transcription were detected at 3-72 h and intrahepatic IL-6 at 24-72 h following single-puncture CLP. All were detected only at 3-16 h following double-puncture CLP and at lower levels than following single-puncture CLP. Loss of serum and intrahepatic IL-6 activity after double-puncture CLP correlated with mortality. Neither intrahepatic nor serum IL-6 levels correlated with intrahepatic IL-6 activity. STAT-3 activation following single-puncture CLP inversely correlated with altered transcription of gluconeogenic, ketogenic, and ureagenic genes. IL-6 may have both beneficial and detrimental effects in sepsis. Fulminant sepsis may decrease the ability of hepatocytes to respond to IL-6.

Organ failure, infection, and the systemic inflammatory response syndrome are associated with elevated levels of urinary intestinal fatty acid binding protein: study of 100 consecutive patients in a surgical intensive care unit

BACKGROUND

Intestinal mucosal ischemia and subsequent barrier dysfunction have been related to the development of organ dysfunction and death in the critically ill. We hypothesized that urine concentrations of intestinal fatty acid binding protein (IFABP), a sensitive marker of intestinal ischemia, might predict the development of the systemic inflammatory response syndrome (SIRS) and organ dysfunction.

METHODS

One hundred consecutive critically ill patients were prospectively studied for the development of infectious complications, organ dysfunction, and SIRS. Urine was collected daily for measurement of IFABP.

RESULTS

A total of 58 males and 42 females (mean age, 56 years; range,16-85 years) were studied. Of these 100 patients, 40 patients developed complications and 5 patients developed SIRS. IFABP was significantly elevated in all patients with SIRS, and IFABP levels peaked an average of 1.4 days (range, 0-7 days) before the diagnosis of SIRS.

CONCLUSION

Elevated concentrations of urine IFABP correlated with the clinical development of SIRS. Studies to assess the utility of IFABP as a predictor of organ dysfunction and SIRS in the critically ill are warranted.

Multiple organ failure can be predicted as early as 12 hours after injury

BACKGROUND

The failure of therapies aimed at modulating systemic inflammatory response syndrome and decreasing multiple organ failure (MOF) has been attributed in part to the inability to identify early the population at risk. Our objective, therefore, was to develop predictive models for MOF at admission and at 12, 24 and 48 hours after injury.

METHODS

Logistic regression models were derived in a data set with 411 adult trauma patients using indicators of tissue injury, shock, host factors, and the Acute Physiology Score-Acute Physiology and Chronic Health Evaluation III (APS-APACHE III).

RESULTS

MOF was diagnosed in 78 patients (19%). Injury Severity Score, platelet count, and age emerged as predictors in all models. Transfused blood, inotropes, and lactate were significant predictors at 12, 24, and 48 hours, but not at admission. The APS-APACHE III emerged only in the 0- to 48-hour model and offered minimal improvement in predictive power. Good predictive power was achieved at 12 hours after injury.

CONCLUSION

Postinjury MOF can be predicted as early as 12 hours after injury. The APS-APACHE III added little to the predictive power of tissue injury, shock and host factors.

Cytokines and adhesion molecules in elective and accidental trauma-related ischemia/reperfusion

BACKGROUND

The major pathophysiologic role of cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, and IL-6, as well as of the (soluble) adhesion molecules ICAM-1 and E-selectin, has been identified using different experimental models of ischemia/reperfusion injury. Moreover, in intensive care management, evaluation of these agents as diagnostic or prognostic tools is of great interest in ischemia/reperfusion injury caused by surgical or accidental trauma. For this reason, inflammatory mediators including those mentioned above were investigated in three different groups of surgical patients.

METHODS

The first group (A, n = 13) comprised patients undergoing elective limb surgery without a tourniquet. The second group (B, n = 36) included patients subjected to limb surgery with a tourniquet. The third group (C, n = 30) was composed of accidental trauma patients who were retrospectively divided into those with and without multiple organ dysfunction (+MOD and -MOD, respectively) as defined by the Denver Score. Serial blood samples were taken during a 5-day (elective surgery) or 14-day (accidental trauma) observation period for monitoring of cytokines and soluble adhesion molecules. The clinical course and the degree of MOD were recorded daily.

RESULTS

Only when a tourniquet was applied for a mean time of 105 minutes did elective limb surgery result in significantly increased serum levels of IL-6, IL,-1ra, and IL-10 but not TNF-RII. Yet, the increase in cytokine levels was not sufficient to cause an enhanced shedding of adhesion molecules, and both soluble ICAM-1 and soluble E-selectin remained unchanged in groups A and B throughout the 5-day observation period. In patients with multiple injuries (group C), all parameters increased early after trauma up to 10- to 20-fold in comparison with the elective limb surgery patients in groups A and B. When the accidental trauma patients were divided according to the Denver Score for +MOD (n = 8, mean Injury Severity Score = 33.8) and -MOD (n = 22, mean Injury Severity Score = 31.2), a clear difference became evident in serum IL-6 and IL-1ra levels within the first 4 days and in serum IL-10 levels for the first 2 days after trauma, with cytokine levels being significantly higher in the +MOD patients 3 to 4 days before the onset of MOD. Although highly elevated, TNF-RII levels did not differentiate between +MOD and -MOD at any time. The increase in serum cytokine levels was associated with a remarkable expression and shedding of ICAM-1 and E-selectin made obvious by significantly increased soluble serum ICAM-1 levels in +MOD patients compared with the -MOD group between days 3 and 5 after trauma and increased soluble serum E-selectin levels between days 2 and 4 after trauma.

CONCLUSION

The release of cytokines and soluble adhesion molecules into the circulation correlates well with the degree of trauma (elective surgery vs. accidental multiple trauma), depending on the extent of the associated ischemia/reperfusion injury. Both groups of mediators are also clearly related to the development of MOD in patients with multiple injuries with generalized ischemia/reperfusion injury caused by hemorrhagic shock. They may be predictive of patients at risk for MOD when measured early in the posttraumatic period.

Influence of arginine, omega-3 fatty acids and nucleotide-supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma

This study investigated the influence of an enteral diet supplemented with arginine, omega-3 fatty acids, and nucleotides (Impact, Sandoz Nutrition, Berne, Switzerland) on the incidence of systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) in patients after severe trauma. Thirty-two patients with an injury-severity score > 20 were included in this prospective, randomized, double-blind, controlled study. Primary endpoints were the incidence of SIRS and MOF. Secondary endpoints were parameters of acute phase and immune response as well as infection rate, mortality, and hospital stay. For statistical analysis 29 patients (test group n = 16, control n = 13) were eligible. In the test group, significantly fewer SIRS days per patient were found during 28 d. The difference was highly significant between d 8-14 (P < 0.001). MOF score was significantly lower in the test group on d 3 and d 8-11 (P < 0.05). Acute phase parameters showed lower C-reactive protein serum levels (significant on D day 4) and fibrinogen plasma levels (significant on d 12 and 14; P < 0.05). HLA-DR expression on monocytes showed significantly higher fluorescence activity on d 7. No significant difference was found for T-lymphocyte CD4/CD8 ratio, interleukin-2 receptor expression, infection rate, mortality (2/16 vs. 4/13), and hospital stay. The results of the study provide further support for beneficial effects of arginine, omega-3-fatty acids and nucleotide-supplemented enteral diet in critically ill patients.

Fatal outcome after polytrauma: multiple organ failure or cerebral damage?

To assess the relative importance of multiple organ failure (MOF) and cerebral damage on the mortality rate following trauma we analyzed retrospectively the records from 99 polytrauma patients admitted to a multidisciplinary European intensive care unit in a 2 year period. In all, 93% of the trauma was non-penetrating and 73% was the result of road accidents. 28 patients died giving an overall mortality of 28.3%. The cause of death was cerebral lesions in 19 patients, hemorrhagic shock in eight and multiple organ failure in one patient who had an injury severity score (ISS) of 13. Most deaths (78%) occurred within 24 h of admission, 15 of these were due to extensive cerebral lesions and seven due to hemorrhagic shock. A total of six deaths occurred after 24 h, four due to extensive cerebral lesions, one due to hemorrhagic shock and one due to multiple organ failure. In our experience, cerebral damage was a more common cause of death than MOF following multiple non-penetrating trauma.

Sepsis-induced depression of rat glucose-6-phosphatase gene expression and activity

Sepsis in rats decreases the hepatic expression of the gluconeogenic enzyme glucose-6-phosphatase (G6Pase). The aim of this study was to investigate the relationship among G6Pase transcription, mRNA, enzymatic activity, and serum glucose levels at different intervals during mild or fulminant sepsis. Both fulminant and mild sepsis immediately decreased hepatic G6Pase mRNA levels. In mild sepsis, levels began to recover late in the time course. Serum glucose levels were maintained in mild sepsis but decreased markedly in fulminant sepsis. G6Pase transcription after fulminant sepsis decreased and never recovered. A similar transcriptional decrease was noted in mild sepsis, but some recovery occurred in this state. Histochemistry after mild sepsis revealed a decrease in G6Pase protein and enzymatic activity that paralleled transcription. These studies suggest that changes in G6Pase transcription and activity are early markers for sepsis-induced alterations in hepatic function. Mechanisms other than gene expression and enzymatic activity serve to maintain glucose levels in mild sepsis, but in the fulminant disorder, compensatory mechanisms fail and hypoglycemia develops.

Cytotoxicity of linoleic acid diols to renal proximal tubular cells

Monoepoxides of linoleic acid (leukotoxin and isoleukotoxin) have been associated with a variety of pathophysiological diseases in humans including multiple organ failure. They also have been shown to be toxic when injected into experimental animals. Because leukotoxin and isoleukotoxin are excellent substrates for epoxide hydrolases, we tested the hypothesis that the diol metabolites are less toxic than the parent monoepoxides using the rabbit renal proximal tubule (RPT) suspension model. An equimolar mixture of the positional isomers of the methyl esters of leukotoxin and isoleukotoxin did not cause cell death to RPT cells at concentrations up to 1 mm using lactate dehydrogenase release as the endpoint. The corresponding diols, however, caused cell death in a time- and concentration-dependent manner beginning at 4 hr and reaching 42% cell death in 6 hr at 1 mm. Cell death was not due to oxidative stress since malondialdehyde content did not increase and the iron chelator deferoxamine and the antioxidant N,N'-diphenyl-1, 4-phenylenediamine were not cytoprotective. In contrast, cell death was associated with mitochondrial dysfunction with respiration decreasing 54% prior to the onset of cell death. Secondary to the mitochondrial dysfunction, the diols completely inhibited active Na+ transport within 30 min of addition. These results suggest that the in vivo toxicity and pathophysiology previously attributed to the monoepoxides of linoleic acid may be due to the diol metabolites.

Rehabilitation results of patients with multiple injuries and multiple organ failure and long-term intensive care

BACKGROUND

Multiple organ failure is regarded to be the major complication of trauma victims treated in the intensive care unit. Long-term rehabilitation results of this special group of patients have not been analyzed so far.

METHODS

Fifty patients with multiple injuries and multiple organ failure (Injury Severity Score > or = 36.8) were followed-up 4.9 +/- 0.3 years after the trauma. To show any organotopic sequelae, laboratory tests for the function of lungs, liver, kidney, and the hematologic system were performed. Additionally their functional (locomotion and neurologic system) and occupational rehabilitation results were investigated.

RESULTS

The laboratory tests showed entirely normal results. The only pathologic values could be found in the lung function tests. Nineteen percent of the patients showed nonphysiologic results in either spirometry, body plethysmography, or diffusion capacity of carbon monoxide. In more than 25% of the patients, permanently decreased range of motion (limitation of more than 30% of the entire range of motion) of the elbow, hip, knee, or ankle joint were found. In 40% of the patients, permanent motoric nerve lesions were identified; in 50% of the patients, permanent sensoric nerve lesions could be verified. The return to work rate was 60%.

CONCLUSIONS

Patients with multiple injuries, who survived multiple organ failure during their long-term intensive care treatment, show an excellent functional and occupational rehabilitation result. They show no major sequelae in their organ function even years after the trauma. Although often these patients suffer from permanent central or peripheral paralysis and decreased range of motion, this finding does not correlate with the patients' ability to return to work.