Abdominal compartment syndrome: the cause or effect of postinjury multiple organ failure

Nuclear factor-kappaB activation by edema inhibits intestinal contractile activity

OBJECTIVE

To investigate the molecular mechanisms leading to edema-induced decreases in intestinal smooth muscle myosin light-chain phosphorylation. Intestinal interstitial edema often develops during abdominal surgery and after fluid resuscitation in trauma patients. Intestinal edema causes decreased intestinal contractile activity via decreased intestinal smooth muscle myosin light-chain phosphorylation, leading to slower intestinal transit. Interstitial edema development is a complex phenomenon, resulting in many changes to the interstitial environment surrounding intestinal smooth muscle cells. Thus, the mechanism(s) by which intestinal edema development causes intestinal dysfunction are likely to be multifactorial.

DESIGN

Randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats, weighing 250-350 g.

INTERVENTION

Studies were performed in a rat model in which a combination of mesenteric venous hypertension and administration of resuscitative fluids induces intestinal edema, mimicking the clinical setting of damage control resuscitation.

MEASUREMENTS AND MAIN RESULTS

Microarray analysis of edematous intestinal smooth muscle combined with an in silico search for overrepresented transcription factor binding sites revealed the involvement of nuclear factor-kappaB in edema-induced intestinal dysfunction. Nuclear factor-kappaB deoxyribonucleic acid binding activity was significantly increased in edematous intestinal smooth muscle compared with controls. Inhibition of nuclear factor-kappaB activation blocked edema-induced decreases in basal intestinal contractile activity. Inhibition of nuclear factor-kappaB activation also attenuated edema-induced decreases in myosin light-chain phosphorylation.

CONCLUSIONS

We conclude that intestinal edema activates nuclear factor-kappaB, which, in turn, triggers a gene regulation program that eventually leads to decreased myosin light-chain phosphorylation and, thus, decreased intestinal contractile activity.

Poloxamer 188 prolongs survival of hypotensive resuscitation and decreases vital tissue injury after full resuscitation

Hypotensive resuscitation prolongs survival of patients with severe bleeding until they can undergo hemorrhage control. However, its value is limited by continuing ischemic injury. Purified poloxamer 188 (P188), a copolymer with rheological and cytoprotective activities, was known to reduce mortality of hemorrhagic shock when used as an adjunct to full resuscitation with fresh whole blood and crystalloid. Studies were undertaken to determine if it could prolong survival and reduce reperfusion injury during prolonged hypotensive resuscitation when added to the best regimen currently available. Unanesthetized rats were bled to a MAP of 30 mmHg for 30 min under computer control. They then received hypotensive resuscitation with Hextend or Hextend + P188 to maintain a MAP of 60 mmHg until death. Poloxamer 188 improved autoresuscitation, reduced fluid requirements, and increased the survivable duration of hypotensive resuscitation by more than 3 h (P < 0.01). Additional studies assessed tissue damage after shock and hypotensive resuscitation with Hextend followed by full resuscitation with crystalloid. In these studies, P188 blunted the no-reflow phenomenon and largely prevented myocardial injury, pulmonary inflammation, small bowel damage, renal tubular necrosis, hepatic central lobular necrosis, and apoptosis of splenic germinal centers that occurred during full resuscitation. Additional studies demonstrated that P188 increased survival from 0% to 75% in 50% volume-controlled hemorrhage (P < 0.001). Finally, P188 did not increase bleeding in uncontrolled hemorrhage produced by 75% tail amputation. Because P188 prolongs survival, decreases fluid requirements, and reduces tissue damage, it deserves further consideration as an adjunct to hypotensive resuscitation.

Current theories on the pathophysiology of multiple organ failure after trauma

Despite the enormous efforts to elucidate the mechanisms of the development of multiple organ failure (MOF) following trauma, MOF following trauma is still a leading cause of late post-injury death and morbidity. Now, it has been proven that excessive systemic inflammation following trauma participates in the development of MOF. Fundamentally, the inflammatory response is a host-defence response; however, on occasion, this response turns around to cause deterioration to host depending on exo- and endogenic factors. Through this review we aim to describe the pathophysiological approach for MOF after trauma studied so far and also introduce the prospects of this issue for the future.

Monitoring trauma and intensive care unit resuscitation with tissue hemoglobin oxygen saturation

INTRODUCTION

The purpose of the present review is to review our experience with near-infrared spectroscopy (NIRS) monitoring in shock resuscitation and predicting clinical outcomes.

METHODS

The management of critically ill patients with goal-oriented intensive care unit (ICU) resuscitation continues to evolve as our understanding of the appropriate physiologic targets improves. It is now recognized that resuscitation to achieve supranormal indices is not beneficial in all patients and may precipitate abdominal compartment syndrome.

RESULTS

Over the years, ICU technology has provided physicians with specific physiologic parameters to guide shock resuscitation. Throughout this time, the tissue hemoglobin oxygen saturation (StO2) monitor has emerged as a non-invasive means to obtain reliable physiologic parameters to guide clinicians' resuscitative efforts. StO2 monitors have been shown to aid in early identification of nonresponders and to predict outcomes in hemorrhagic shock and ICU resuscitation. These data have also been used to better understand and refine existing resuscitation protocols. More recently, use of NIRS technology to guide resuscitation in septic shock has been shown to predict outcomes in high-risk patients.

CONCLUSIONS

StO2 is an important tool in identifying high-risk patients in septic and hemorrhagic shock. It is a non-invasive means of obtaining vital information regarding outcome and adequacy of resuscitation.

Resuscitation-induced intestinal edema and related dysfunction: state of the science

High volume resuscitation and damage control surgical methods, while responsible for significantly decreasing morbidity and mortality from traumatic injuries, are associated with pathophysiologic derangements that lead to subsequent end organ edema and dysfunction. Alterations in hydrostatic and oncotic pressures frequently result in intestinal edema and subsequent dysfunction. The purpose of this review is to examine the principles involved in the development of intestinal edema, current and historical models for the study of edema, effects of edema on intestinal function (particularly ileus), molecular mediators governing edema-induced dysfunction, potential role of mechanotransduction , and therapeutic effects of hypertonic saline. We review the current state of the science as it relates to resuscitation induced intestinal edema and resultant dysfunction.

Postinjury multiple organ failure

Postinjury multiple organ failure (MOF) became prevalent as the improvements in critical care during the 1970s made it possible to keep trauma patients alive with single organ injury. Enormous efforts invested in laboratory and clinical research made it possible to better understand the epidemiology and pathophysiology of the syndrome. This has translated to improved strategies in prediction, prevention and treatment of MOF. With changes in population demographics and injury mechanisms and improvements in trauma care, changes in the epidemiology of MOF are also becoming evident. Significant improvements in trauma patient management decreased the severity and mortality of MOF, but the syndrome still remains the most significant contributor of late postinjury mortality and intensive care unit resource utilisation. This review defines the essential MOF-related terminology, summarises the changing epidemiology of MOF, describes our current understanding of the pathophysiology, discusses the available strategies for prevention/treatment based on the identified independent predictors and provides future directions for research.

Intra-abdominal hypertension: evolving concepts

This article focuses primarily on the recent literature on abdominal compartment syndrome (ACS) and the definitions and recommendations published by the World Society for the Abdominal Compartment Syndrome. The definitions regarding increased intra-abdominal pressure (IAP) are listed and are followed by an overview of the different mechanisms of organ dysfunction associated with intra-abdominal hypertension (IAH). Measurement techniques for IAP are discussed, as are recommendations for organ function support and options for treatment in patients who have IAH. ACS was first described in surgical patients who had abdominal trauma, bleeding, or infection; but recently, ACS has been described in patients who have other pathologies. This article intends to provide critical care physicians with a clear insight into the current state of knowledge regarding IAH and ACS.

Computerized clinical decision support for traumatic shock resuscitation

PURPOSE OF REVIEW

To review what we learned through implementation of computerized decision support for ICU resuscitation of major torso trauma patients who arrive in shock.

RECENT FINDINGS

Overall, these patients respond well to preload-directed goal-orientated ICU resuscitation; however, the subset of patients destined to develop abdominal compartment syndrome do not respond well. In fact, this strategy precipitates the full-blown syndrome that is a new iatrogenic variant of multiple organ failure. The clinical trajectory of abdominal compartment syndrome starts early after emergency department admission and its course is fairly well defined by the time patients reach the ICU. It occurs in patients who arrive with severe bleeding that is not readily controlled. These patients require a very different emergency department management strategy. Hemorrhage control is paramount. Alternative massive transfusion protocols should be used with an emphasis on hemostasis and avoidance of excessive isotonic crystalloids. Finally, near-infrared spectroscopy that measures tissue hemoglobin saturation in skeletal muscle (StO2) is good at identifying high-risk patients. A falling StO2 in the setting of ongoing resuscitation is a harbinger of death from early exsanguination and multiple organ failure.

SUMMARY

Fundamental changes are needed in the care of trauma patients who arrive in shock and require a massive transfusion.

Gastrointestinal microcirculation and cardiopulmonary function during experimentally increased intra-abdominal pressure

OBJECTIVES

The aim of this study was to assess gastric, intestinal, and renal cortex microcirculation parallel with central hemodynamics and respiratory function during stepwise increase of intra-abdominal pressure (IAP).

DESIGN

Prospective, controlled animal study.

SETTING

Research laboratory, University Hospital.

SUBJECTS

Twenty-six anesthetized and mechanically ventilated pigs.

INTERVENTIONS

Following baseline registrations, CO2 peritoneum was inflated (n = 20) and IAP increased stepwise by 10 mm Hg at 10 mins intervals up to 50 mm Hg and subsequently exsufflated. Control animals (n = 6) were not insufflated with CO2.

MEASUREMENTS AND MAIN RESULTS

The microcirculation of gastric mucosa, small bowel mucosa, small bowel seromuscular layer, colon mucosa, colon seromuscular layer, and renal cortex were selectively studied at all pressure levels and after exsufflation using a four-channel laser Doppler flowmeter (Periflex 5000, Perimed). Central hemodynamic and respiratory function data were registered at each level and after exsufflation. Cardiac output decreased significantly at IAP levels above 10 mm Hg. The microcirculation of gastric mucosa, renal cortex and the seromuscular layer of small bowel and colon was significantly reduced with each increase of IAP. The microcirculation of the small bowel mucosa and colon mucosa was significantly less affected compared with the serosa (p < 0.01).

CONCLUSIONS

Our animal model of low and high IAP by intraperitoneal CO2-insufflation worked well for studies of microcirculation, hemodynamics, and pulmonary function. During stepwise increases of pressure there were marked effects on global hemodynamics, respiratory function, and microcirculation. The results indicate that intestinal mucosal flow, especially small bowel mucosal flow, although reduced, seems better preserved in response to intra-abdominal hypertension caused by CO2-insufflation than other intra-abdominal microvascular beds.

Abdominal compartment syndrome

Increased intra-abdominal pressure (IAP) has received growing attention in critically ill patients. Pathophysiologically, it deranges cardiovascular haemodynamics, respiratory and renal functions and may eventually lead to multi-organ failure. It is primarily seen in surgical intensive care units and is frequently associated with abdominal trauma but also occurs after elective abdominal surgery. Non-surgical intensivists ought to be aware that the syndrome is also seen in a wide spectrum of medical conditions, e.g. acute pancreatitis. An expert panel has recently set up definitions of intra-abdominal hypertension (IAH, sustained or repeated pathological elevation in IAP > or = 12 mmHg) and abdominal compartment syndrome (ACS, sustained IAP > 20 mmHg associated with a new organ dysfunction or failure). As clinical signs of IAH are unreliable, IAP should be measured non-invasively by the 'bladder technique'. It is hoped that the consensus definitions will contribute to a broader recognition and effective treatment of this life-threatening syndrome.

Is there a role for aggressive use of fresh frozen plasma in massive transfusion of civilian trauma patients?

BACKGROUND

Damage control resuscitation (DCR) with early plasma in combat casualties requiring massive transfusion (MT) decreases early deaths from bleeding.

METHODS

To ascertain the potential role of early plasma DCR in civilian MT, we queried a prospective traumatic shock database of 383 civilians.

RESULTS

Ninety-three (24%) of the traumatic shock civilians received a MT, of which 26 (28%) died early, predominantly from bleeding within 6 hours. Comparatively, this early MT death cohort arrived in more severe shock and were coagulopathic (mean INR 2.4). In the critical period of MT (ie, the first 3 hours), these patients received 20 U of packed red blood cells (PRBCs) but only 4 U of fresh frozen plasma (FFP). They remained severely acidotic and their coagulopathy worsened as they exsanquinated.

CONCLUSION

Civilians who arrived in traumatic shock, required a MT, and died early had worsening coagulopathy, which was not treated. DCR with FFP may have a role in civilian trauma.

Intestinal edema: effect of enteral feeding on motility and gene expression

OBJECTIVE

Edema formation, inflammation, and ileus in the intestine are commonly seen in conditions like gastroschisis, inflammatory bowel disease, and cirrhosis. We hypothesized that early enteral feeding would improve intestinal transit. We also wanted to study the impact of early enteral feeding on global gene expression in the intestine.

DESIGN

Rats were divided into Sham or Edema +/- immediate enteral nutrition (IEN). At 12 h, small intestinal transit via FITC-Dextran and tissue water were measured. Ileum was harvested for total RNA to analyze gene expression using cDNA microarray with validation using real-time PCR. Data are expressed as mean +/- SEM, n = 4-6 and (*), (**) = P < 0.05 versus all groups using ANOVA.

RESULTS

IEN markedly improved intestinal transit with minimal genetic alterations in Edema animals. Major alterations in gene expression were detected in primary, cellular and macromolecular metabolic activities. Edema also altered more genes involved with the regulation of the actin cytoskeleton.

CONCLUSIONS

Intestinal edema results in impaired small intestinal transit and globally increased gene expression. Early enteral nutrition improves edema-induced impaired transit and minimizes gene transcriptional activity.

Incidence and clinical effects of intra-abdominal hypertension in critically ill patients

OBJECTIVE

The objective of this study was to determine the epidemiology and outcomes of intra-abdominal hypertension in a heterogeneous intensive care unit population.

DESIGN

This was a prospective cohort study.

SETTING

This study was conducted at a medical-surgical intensive care unit in a university hospital.

PATIENTS

Study patients included all those consecutively admitted during 9 months, staying > 24 hrs, and requiring bladder catheterization.

MEASUREMENTS AND MAIN RESULTS

On admission, epidemiologic data and risk factors for intra-abdominal hypertension were studied; then, daily maximal and mean intra-abdominal pressures (IAP(max) and IAP(mean)), abdominal perfusion pressure, fluid balances, filtration gradient, and sequential organ failure assessment score, were registered. IAPs were recorded through a bladder catheter every 6 hrs until death, discharge, or along 7 days. Intra-abdominal hypertension was defined as IAP > or = 12 mm Hg. Abdominal compartment syndrome was defined as IAP > or = 20 mm Hg plus > or = 1 new organ failure. Main outcome measure was hospital mortality. Of 83 patients, considering IAP(max), 31% had intra-abdominal hypertension on admission and another 33% developed it after (23% and 31% with IAP(mean)). Main risk factors were mechanical ventilation, acute respiratory distress syndrome, and fluid resuscitation (relative risk, 5.26, 3.19, and 2.50, respectively). Patients with intra-abdominal hypertension were sicker, had higher mortality (53% vs. 27%, p = .02), and consistently showed higher total and renal sequential organ failure assessment score, daily and cumulative fluid balances, and lower filtration gradient. Nonsurvivors had higher IAP(max), IAP(mean), and fluid balances and lower abdominal perfusion pressure. Abdominal compartment syndrome developed in 12%; 20% survived. Logistic regression identified IAP(max) as an independent predictor of mortality (odds ratio, 1.17; 95% confidence interval, 1.05-1.30; p = .003) after adjusting with Acute Physiology and Chronic Health Evaluation II and comorbidities (odds ratio, 1.15; 95% confidence interval, 1.06-1.25; p = .001; and odds ratio, 2.68; 95% confidence interval, 1.27-5.67; p = .013, respectively). Models with IAP(mean) and abdominal perfusion pressure also performed well. Areas under receiver operating characteristic curves were .81 and .83.

CONCLUSIONS

Intra-abdominal hypertension, diagnosed either with IAP(max) or IAP(mean), was frequent and showed an independent association with mortality. Intra-abdominal hypertension was significantly associated with more severe organ failures, particularly renal and respiratory, and a prolonged intensive care unit stay.

Hypertonic saline modulation of intestinal tissue stress and fluid balance

Crystalloid-based resuscitation of severely injured trauma patients leads to intestinal edema. A potential mechanism of intestinal edema-induced ileus is a reduction of myosin light chain phosphorylation in intestinal smooth muscle. We sought to determine if the onset of edema initiated a measurable, early mechanotransductive signal and if hypertonic saline (HS) can modulate this early signal by changing intestinal fluid balance. An anesthetized rat model of acute interstitial intestinal edema was used. At laparotomy, the mesenteric lymphatic was cannulated to measure lymph flow and pressure, and a fluid-filled micropipette was placed in the intestinal submucosa to measure interstitial pressure. Rats were randomized into four groups (n=6 per group): sham, mesenteric venous hypertension+80 mL/kg 0.9% isotonic sodium chloride solution (ISCS 80), mesenteric venous hypertension+80 mL/kg 0.9% ISCS+4 mL/kg 7.5% saline (ISCS 80+HS), or 4 mL/kg 7.5% saline (HS alone) to receive the aforementioned intravenous fluid administered over 5 min. Measurements were made 30 min after completion of the preparation. Tissue water, lymph flow, and interstitial pressure were measured. Resultant applied volume induced stress on the smooth muscle (sigmaravi-muscularis) was calculated. Mesenteric venous hypertension and crystalloid resuscitation caused intestinal edema that was prevented by HS. Intestinal edema caused an early increase in intestinal interstitial pressure that was prevented by HS. Hypertonic saline did not augment lymphatic removal of intestinal edema. sigmaravi-muscularis was increased with onset of edema and prevented by HS, paralleling the interstitial pressure data. Intestinal edema causes an early increase in interstitial pressure that is prevented by HS. Prevention of the edema-induced increase in interstitial pressure serves to blunt the mechanotransductive signal of sigmaravi-muscularis.

Computerized clinical decision support: a technology to implement and validate evidence based guidelines

Faced with a documented crisis of patients not receiving appropriate care, there is a need to implement and refine evidence-based guidelines (EBGs) to ensure that patients receive the best care available. Although valuable in content, among their deficiencies, EBGs do not provide explicit methods to bring proven therapies to the bedside. Computerized information technology, now an integral part of the US healthcare system at all levels, presents clinicians with information from laboratory, imaging, physiologic monitoring systems, and many other sources. It is imperative that we clinicians use this information technology to improve medical care and efficacy of its delivery. If we do not do this, nonclinicians will use this technology to tell us how to practice medicine. Computerized clinical decision support (CCDS) offers a powerful method to use this information and implement a broad range of EBGs. CCDS is a technology that can be used to develop, implement, and refine computerized protocols for specific processes of care derived from EBGs, including complex care provided in intensive care units. We describe this technology as a desirable option for the trauma community to use information technology and maintain the trauma surgeon/intensivist's essential role in specifying and implementing best care for patients. We describe a process of logical protocol development based on standardized clinical decision making to enable EBGs. The resulting logical process is readily computerized, and, when properly implemented, provides a stable platform for systematic review and study of the process and interventions.

CONCLUSION

: CCDS to implement and refine EBG derived computerized protocols offers a method to decrease variability, test interventions, and validate improved quality of care.

Edema-induced intestinal dysfunction is mediated by STAT3 activation

Increased signal transducer and activator of transcription 3 (STAT3) activation has been shown to be associated with intestinal dysfunction. The purpose of this study was to investigate the role of STAT3 in edema-induced intestinal dysfunction. Intestinal edema was induced in male Sprague-Dawley rats by a combination of mesenteric venous hypertension and fluid resuscitation (RESUS + VH). Resuscitation fluid alone (RESUS), venous hypertension alone (VH), and sham-operated rats (CONTROL) were used as controls. Edema development, STAT3 DNA binding activity, nuclear translocation, and phosphorylation were measured in rat distal small intestinal muscularis. A significant amount of edema development was measured in the RESUS + VH rats compared with CONTROL and VH from 30 min to 6 h after surgery. Edema developed in the RESUS group at 30 min postsurgery but resolved before 2 h postsurgery. A significant increase in STAT3 DNA binding activity was observed from 30 min to 6 h after surgery in the edematous RESUS + VH group compared with nonedematous CONTROL. In addition, a significant increase in STAT3 nuclear translocation and phosphorylation was measured in the RESUS + VH group 2 and 6 h after surgery. No significant increases in STAT3 activation were observed in either the RESUS or VH groups compared with CONTROL. Rats in both the RESUS + VH and CONTROL groups were pretreated with AG490 (5 mg/kg, i.p.) to block STAT3 activation. Signal transducer and activator of transcription 3 inhibition attenuated edema-induced decrease in intestinal contractile activity and myosin light chain phosphorylation. We conclude from these data that edema-induced decreases in intestinal contractile activity are mediated, at least in part, by STAT3 activation.

Packing for control of hemorrhage in major liver trauma

BACKGROUND

Packing for complex liver injuries has been associated with an increased risk of abdominal sepsis and bile leaks. The aim of the present study was to determine the optimum timing of pack removal and to assess whether the total duration of packing increases the incidence of these complications.

METHODS

The study was based on a retrospective review of all patients requiring liver packing over an 8-year period in a level 1 trauma center.

RESULTS

Ninety-three (17%) of 534 liver injuries identified at laparotomy required perihepatic packing. Penetrating and blunt trauma occurred in 72 (77%) and 21 (23%), respectively. The mean total duration of packing was 2.4 days (range: 0.5-6.0 days). There was no association between the total duration of packing and the development of liver-related complications (P = 0.284) or septic complications (P = 0.155). Early removal of packs at 24 h was associated with a higher rate of re-bleeding than removal of packs at 48 h (P = 0.006).

CONCLUSIONS

The total duration of liver packing does not result in an increase in septic complications or bile leaks. The first re-look laparotomy should only be performed after 48 h. An early re-look at 24 h is associated with re-bleeding and does not lead to early removal of liver packs.

Acute Lung Injury and Multiple Organ Dysfunction Syndrome Secondary to Intra-Abdominal Hypertension and Abdominal Decompression in Extensively Burned Patients

BACKGROUND

Secondary abdominal compartment syndrome (ACS) is a lethal complication after resuscitation from burn shock, even after abdominal decompression (AD) is performed. This study investigated increased susceptibility to multiple organ dysfunction syndrome (MODS) in extensively burned patients with ACS.

METHODS

Patients admitted to our burn unit between 2002 and 2005 with burns affecting 40% or more of the total body surface area without severe inhalation injury were analyzed. Hemodynamic parameters, blood gas analysis, and intrabladder pressure as intra-abdominal pressure were recorded. Serum interleukin (IL)-8 and IL-6 concentrations were measured in 20 of these patients. Lung injury score and Sequential Organ Failure Assessment scores were serially determined.

RESULTS

Fourteen of 38 patients developed intra-abdominal hypertension in 22.9 +/- 8.9 hours postburn. Hemodynamic parameters in these 14 patients, including peak intra-abdominal pressure (46.6 +/- 11.2 to 19.8 +/- 9.9 cm H2O), peak inspiratory pressure (51.4 +/- 10.5 to 31.8 +/- 7.0 cm H2O), and abdominal perfusion pressure (51.3 +/- 18.3 to 73.9 +/- 13.6 mm Hg), were improved immediately after AD. Despite AD, lung injury score and Sequential Organ Failure Assessment scores increased significantly 2 and 3 days postburn in patients who required AD. Plasma concentration of IL-8 was elevated in intra-abdominal hypertension patients 3 days postburn.

CONCLUSION

Intra-abdominal hypertension induced acute lung injury and MODS with IL-8 elevation, even though AD improved hemodynamic parameters in extensively burned patients.

Hypertonic saline reverses stiffness in a Sprague-Dawley rat model of acute intestinal edema, leading to improved intestinal function

INTRODUCTION

Acute edema induced by resuscitation and mesenteric venous hypertension impairs intestinal transit and contractility and reduces intestinal stiffness. Pretreatment with hypertonic saline (HS) can prevent these changes. Changes in tissue stiffness have been shown to trigger signaling cascades via stress fiber formation. We proposed that acute intestinal edema leads to a decrease in intestinal transit that may be mediated by changes in stiffness, leading to stress fiber formation and decreased intestinal transit. Furthermore, HS administration will abolish these detrimental effects of edema.

RESULTS

Intestinal edema causes a significant increase in tissue water and a significant decrease in intestinal transit and stiffness compared with sham. HS reversed these changes to sham levels. In addition, tissue edema led to significant stress fiber formation and decreased numbers of focal contacts. HS preserved tissue stiffness, prevented stress fiber formation, and was associated with improved intestinal function.

CONCLUSION

HS eliminates intestinal tissue edema formation and improves intestinal transit. In addition, the action of HS may be mediated through its preservation of tissue stiffness, which leads to prevention of signaling via stress fiber formation, leading to preserved intestinal function. Finally, intestinal edema may provide a novel physiologic model for examining stiffness and stress fiber signaling.

Secondary abdominal compartment syndrome: a potential threat for all trauma clinicians

Post-injury abdominal compartment syndrome (ACS) is an increasingly recognised phenomenon in critical care. During the last decade, ACS had also been characterised in patients without abdominal injuries, referred to as secondary ACS. Recent investigation has described this elusive syndrome better, with up to 70% mortality. Regardless of the cause of the syndrome and the nature of any extra-abdominal injuries, secondary ACS is invariably associated with massive fluid resuscitation. With a reliable, predictive model and new monitoring techniques, trauma clinicians should be able to identify the high-risk patient and attenuate the impact of this syndrome.

Morphology, TNFα expression and apoptosis in the hearts of patients who died of abdominal compartment syndrome: An immunohistochemical study

Most of the existing reports on abdominal compartment syndrome (ACS) deal with pathophysiology, focusing on its clinical picture and course, and knowledge of the histopathological features of ACS is very poor. Since the heart, kidneys and lungs are the organs primarily targeted for injury in multi-organ failure, we investigated the expression of TNFalpha and apoptosis in tissue specimens of the heart. This retrospective study was conducted at the Department of Forensic Pathology, University of Foggia. A retrospective review of records extending over a period of 4 years, from 1 April 2001 to 31 March 2005, was carried out and all cases subjected to medico-legal autopsy during this period, whose detailed history and case records were available, were the subjects of our study. Over a 4-year period, on 848 cases subjected to medico-legal autopsy, three cases qualified for inclusion into the study. The immunohistochemical study revealed an intensive positive result for TNFalpha in heart specimens. The TUNEL assay was positive in heart specimens too. The presented study can contribute to elucidate the pathophysiology of fatal ACS and also define efficient markers for future therapeutic approaches suggesting anti-TNFalpha strategies may be useful in the management of ACS.

The open abdomen in trauma: do infectious complications affect primary abdominal closure?

OBJECTIVE

One of the primary goals of damage control surgery in the trauma patient is primary closure of the abdomen. We hypothesized that extra-abdominal infections, such as those complicating injuries to the thorax, diaphragm, long bones, or musculoskeletal system, would decrease the likelihood of primary abdominal closure and increase hospital resource utilization in patients requiring open abdominal management.

METHODS

The trauma registry of the American College of Surgeons (TRACS) was reviewed retrospectively from 1995-2002 for open abdomen technique and damage control surgery. The outcome was primary fascial closure or delayed closure. Patients who died prior to closure were excluded. We evaluated infectious complications, including ventilator-associated pneumonia (VAP), blood stream infection (BSI), and surgical site infection (SSI). Other parameters studied were multiple rib fractures, long bone fractures, chest injuries, diaphragm injuries, empyema, and transfusion requirements. Hospital charges were obtained from the hospital administrative database. Univariate, multivariate, and regression analyses were performed to identify the effects of infectious complications on primary abdominal closure, length of stay, total hospital charges, and disposition.

RESULTS

Three hundred forty-four patients required the open abdomen technique: 67% received damage control laparotomy and 33% decompression of abdominal compartment syndrome. Two hundred seventy-six patients (80%) went on to abdominal closure of some form and constituted the primary study group. Primary abdominal closure was achieved in 180 (65%) with a mean time to closure of 3.5 days. Ventilator-associated pneumonia, BSI, and SSI were associated with lack of primary closure (p < 0.05). Increased blood transfusions also were associated with failure of primary closure (p < 0.05). Ventilator-associated pneumonia and BSI were associated with significantly greater lengths of stay in the intensive care unit (ICU) (24.2 days vs. 12.6 days and 30.5 days vs. 17.9 days; both p < 0.0001) and significantly greater total hospital charges (232,080 US dollar vs. 142,893 US dollar; 247,440 US dollar vs. 160,940 US dollar; and 264,778 US dollar vs. 170,447 US dollar; all p < 0.001).

CONCLUSION

Inability to achieve primary abdominal closure was associated with infectious complications (VAP, BSI, and SSI) and large transfusion requirements. Infectious complications also significantly increased ICU utilization and hospital charges. Death was associated with BSI, femur fractures, and large transfusion requirements, whereas infectious complications did not have a significant impact on discharge disposition.

Secondary abdominal compartment syndrome in a case of pediatric trauma shock resuscitation

OBJECTIVE

To report a rare case of secondary abdominal compartment syndrome during shock resuscitation in a pediatric trauma patient.

DESIGN

Case report and literature review.

SETTING

A community hospital and a designated children's trauma hospital.

PATIENT

A 17-yr-old trauma patient.

INTERVENTIONS

Advanced trauma life support, trauma laparotomy, and superficial temporal artery ligation.

MEASUREMENTS AND MAIN RESULTS

A 17-yr-old trauma patient with ongoing blood loss from a lacerated superficial temporal artery received aggressive crystalloid resuscitation before arrival at a designated trauma hospital. His injury severity score was 16. The first hemoglobin drawn was 55 g/L with a hematocrit of 0.16 L/L. Within 3 hrs of the trauma, an abdominal computed tomography scan demonstrated a moderate amount of free peritoneal fluid, edematous bowel with marked enhancement, and a compressed inferior vena cava. Shortly after completion of imaging studies, the patient's abdomen became increasingly tense with poor perfusion to the lower extremities. Urgent laparotomy for abdominal compartment syndrome identified excessive ascites and extensive bowel edema with no blood or traumatic injuries. Abdominal decompression resulted in immediate improvement of hemodynamics and restored lower limb perfusion. Primary abdominal closure was obtained and the patient recovered fully with gentle diuresis.

CONCLUSIONS

Secondary abdominal compartment syndrome developed in this pediatric trauma patient with hemorrhagic shock, possibly from aggressive crystalloid resuscitation. This trauma case highlights the importance of early hemorrhagic control with balanced crystalloid/transfusion therapy. Secondary abdominal compartment syndrome in pediatric trauma is rare and may reflect physiologic differences during development, less aggressive resuscitation practices, and/or underrecognition.

Intestinal edema decreases intestinal contractile activity via decreased myosin light chain phosphorylation

OBJECTIVE

The purpose of this study was to investigate the effects of interstitial edema on intestinal contractile activity.

DESIGN

Randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTION

Intestinal edema was induced in rats by a combination of fluid infusion and mesenteric venous hypertension. Rats were divided into four groups: CONTROL, sham; RESUS, saline infusion only; RESUS+VH, saline infusion and venous hypertension; and VH, venous hypertension only. Edema development, basal contractile activity, maximum agonist-induced contractile response (measured as total force generation during the first 2 mins after carbachol treatment), and myosin light chain phosphorylation were measured in the distal small intestine.

MEASUREMENTS AND MAIN RESULTS

The amount of interstitial fluid, indicated by the wet-to-dry ratio, increased significantly in both the RESUS and RESUS+VH groups as early as 30 mins after surgery compared with the CONTROL group. Whereas the tissue fluid remained significantly elevated in the RESUS+VH group up to 6 hrs after surgery, the RESUS group wet-to-dry ratios returned to CONTROL group levels by 2 hrs after surgery. Basal contractile activity was significantly less in the RESUS+VH group compared with either the RESUS group or the CONTROL group 6 hrs after surgery. Maximum contractile response decreased significantly in the RESUS+VH group compared with the RESUS group. Basal contractile activity and maximum contractile response did not change significantly in the VH group compared with the CONTROL group. The phosphorylated fraction of myosin light chain was significantly lower in the RESUS+VH group compared with the CONTROL group at 0.5, 2, and 6 hrs after surgery.

CONCLUSION

We conclude that edema decreases myosin light chain phosphorylation, leading to decreased intestinal contractile activity.

Results from the International Conference of Experts on Intra-abdominal Hypertension and Abdominal Compartment Syndrome. I. Definitions

OBJECTIVE

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) have been increasingly recognized in the critically ill over the past decade. The variety of definitions proposed has led to confusion and difficulty in comparing one study to another.

DESIGN

An international consensus group of critical care specialists convened at the second World Congress on Abdominal Compartment Syndrome to standardize definitions for IAH and ACS based upon the current understanding of the pathophysiology surrounding these two syndromes.

METHODS

Prior to the conference the authors developed a blueprint for the various definitions, which was further refined both during and after the conference. The present article serves as the final report of the 2004 International ACS Consensus Definitions Conference and is endorsed by the World Society of Abdominal Compartment Syndrome (WSACS).

RESULTS

IAH is redefined as an intra-abdominal pressure (IAP) at or above 12 mmHg. ACS is redefined as an IAP above 20 mmHg with evidence of organ dysfunction/failure. ACS is further classified as either primary, secondary, or recurrent based upon the duration and cause of the IAH-induced organ failure. Standards for IAP monitoring are set forth to facilitate accuracy of IAP measurements from patient to patient.

CONCLUSIONS

State-of-the-art definitions for IAH and ACS are proposed based upon current medical evidence as well as expert opinion. The WSACS recommends that these definitions be used for future clinical and basic science research. Specific guidelines and recommendations for clinical management of patients with IAH/ACS are published in a separate review.

Use of power Doppler ultrasound to monitor renal perfusion during burn shock

BACKGROUND

Renal cortical blood flow can be quantified by means of power Doppler ultrasound (PDUS) image analysis. We hypothesized that renal cortical perfusion, estimated by PDUS image intensity (PDUSII), would decrease during burn shock and improve during resuscitation in a porcine model.

METHODS

Eight anesthetized swine sustained a 75% scald injury. Resuscitation began 6h postburn. Renal cortical blood flow was measured directly using fluorescent microspheres (CORFLO), and was estimated noninvasively by PDUSII. PDUSII, CORFLO, and cardiopulmonary data were recorded every 2h.

RESULTS

PDUSII decreased significantly from preburn to postburn hour 6, and increased with resuscitation by hour 8. CORFLO correlated well with PDUS image intensity (n=48, r(2)=0.696) but poorly with urine output (n=48, r(2)=0.252).

CONCLUSION

PDUS in this study was superior to the urine output in assessing renal cortical microvascular blood flow during shock and resuscitation, and may be useful in the care of injured patients.

Hypertonic saline resuscitation prevents hydrostatically induced intestinal edema and ileus

OBJECTIVE

We have shown that acute edema induced by mesenteric venous hypertension (MV-HTN) impairs intestinal transit and reduces the standardized engineering measures of intestinal stiffness (elastic modulus) and residual stress (opening angle). We hypothesized that hypertonic saline (7.5%) would reverse these detrimental effects of acute edema.

DESIGN

Laboratory study.

SETTING

University laboratory.

SUBJECTS

Male Sprague Dawley rats (270-330 g).

INTERVENTIONS

Rats were randomized to five groups: sham, MV-HTN alone, MV-HTN with 4 mL/kg normal saline resuscitation (equal volume), MV-HTN with 33 mL/kg normal saline resuscitation (equal salt), and MV-HTN with 4 mL/kg hypertonic saline. Intestinal edema was measured by wet to dry tissue weight ratio. A duodenal catheter was placed and, 30 mins before death, fluorescein isothiocyanate Dextran was injected. At death, dye concentrations were measured to determine intestinal transit. Segments of distal ileum were hung to a fixed point in a tissue bath and to a force displacement transducer and stretched in increments of 1 mm; we recorded the new length and the corresponding force from the force displacement transducer to determine elastic modulus. Next, two transverse cuts were made yielding a 1- to 2-mm thick ring-shaped segment of tissue which was then cut radially to open the ring. Then the opening angle was measured.

MEASUREMENTS AND MAIN RESULTS

MV-HTN, MV-HTN with 4 mL/kg normal saline, and MV-HTN with 33 mL/kg normal saline caused a significant increase in tissue edema and a significant decrease in intestinal transit, stiffness, and residual stress compared with sham. Hypertonic saline significantly lessened the effect of edema on intestinal transit and prevented the changes in stiffness and residual stress.

CONCLUSIONS

Hypertonic saline prevented intestinal tissue edema. In addition, hypertonic saline improved intestinal transit, possibly through more efficient transmission of muscle force through stiffer intestinal tissue.

Dietary restriction compromises resistance to gut ischemia-reperfusion, despite reduction in circulating leukocyte activation

BACKGROUND

Gut ischemia-reperfusion (gut I/R) accompanying severe surgical insults leads to neutrophil-mediated injury and is regarded as a triggering event in early multiple-organ failure. Our previous study demonstrated dietary restriction to down-regulate leukocyte activation. Therefore, we hypothesized dietary restriction might be beneficial in terms of surviving I/R. We also evaluated leukocyte activation and the level of organ glutathione, an antioxidative substance.

METHODS

Institute of Cancer Research mice received chow, 170 (ad libitum), 119 (MR: mild restriction) or 68 (SR: severe restriction) g/kg per day for 7 days. Exp. 1: The mice (n = 59) underwent 15 or 45 minutes of gut ischemia and survival was observed. Exp. 2: The mice (n = 73) were killed before or 60 or 120 minutes after 15-minute ischemia. Reactive oxygen intermediate (ROI) production by circulating myeloid cells and CD11b expression was determined. Some mice were assessed for nuclear factor kappa B (NFkappaB) activation. Glutathione levels were measured in some of the small intestine and liver samples from each group.

RESULTS

Dietary restriction decreased survival. Circulating myeloid cell priming and activation, in terms of ROI production and CD11b expression, were enhanced in the ad libitum group but not in the restricted groups. NFkappaB was activated only in the ad libitum group. Gut and hepatic glutathione levels were lower in the SR than in the ad libitum group. Dietary restriction caused histologic damages in gut, liver, and lung 120 minutes after reperfusion.

CONCLUSIONS

Dietary restriction blunts leukocyte priming and activation after gut ischemic insult but worsens the outcome by, at least in part, decreasing antioxidative activities. Clinically, nutrition replenishment may be required to improve the outcome of gut hypoperfusion.

Influence of gender and age on T-cell responses in a murine model of trauma-hemorrhage: differences between circulating and tissue-fixed cells

Clinical studies indicate that peripheral blood lymphocyte functions are depressed following trauma; however, it is unclear whether tissue-fixed lymphocyte functions are also altered under those conditions. Moreover, the impact of gender and age on peripheral T-cell responses following trauma-hemorrhage (TH) are unknown. To study this, immature (approximately 3 wk of age), mature (approximately 7 wk of age), and aged (approximately 23 mo of age) male and proestrus female C3H/HeN mice were sham operated or subjected to trauma (i.e., midline laparotomy) and hemorrhagic shock (30+/-5 mmHg for 90 min). Twenty-four hours after resuscitation, blood and splenocytes were harvested and T-cell functions assessed. In immature animals, TH induced an enhanced immune response in the splenic compartment and a suppressed response in the peripheral blood mononuclear cells (PBMC) that was independent of gender. Differential responses were observed in cells from mature mice. Splenic responses were enhanced following TH, independent of gender, whereas PBMC displayed gender dimorphism with suppressed proliferation and T-cell helper 1 responses in males but not in females. A similar pattern was observed in cells from aged mice. Splenic T cells from male mice displayed a suppressed CD4-to-CD8 ratio after TH, whereas no such change was observed in cells from proestrus females. In contrast, only PBMC from mature males displayed a suppressed CD4-to-CD8 ratio after TH. Thus gender differences exist in PBMC responses after TH that do not necessarily correlate with changes in the tissue-fixed compartment. Age is also an important factor in the immune responses after TH. In view of this, both gender and age should be taken into consideration in evaluating the immune status and in treatment of TH shock.

Transfusion of the injured patient: proceed with caution

Transfusion of the injured patient with packed red blood cells (PRBCs) is a dynamic process requiring vigilance during the acute resuscitative and recovery phases postinjury. Although adverse events have been reported in 2% to 10% of injured patients, the advent of new detection techniques for viral pathogens has markedly decreased the risk of infectious transmission. However, transfusions are strongly associated with immunosuppression in the host, which may occur days after the initial injury and may lead to bacterial infections. Conversely, early transfusion of stored PRBCs, > 6 units in the first 12 h postinjury, contributes to an early state of hyperinflammation that is a strong, independent predictor of multiple organ failure (MOF) in those patients with intermediate injury severity scores. The roles of prestorage leukoreduction are also reviewed with respect to the promotion of both immunosuppression and hyperinflammation. We further summarize studies with hemoglobin substitutes, whose use may obviate many of the untoward events of transfusion and promise to lead to better outcomes for injured patients.

Complications of Nonoperative Management of High-Grade Blunt Hepatic Injuries

BACKGROUND

Nonoperative management of blunt hepatic injuries is highly successful. Complications associated with high-grade injuries, however, have not been well characterized. The purpose of the present study was therefore to define hepatic-related complications and associated treatment modalities in patients undergoing nonoperative management of high-grade blunt hepatic injuries.

METHODS

Three hundred thirty-seven patients from two regional Level I trauma centers with grade 3 to 5 blunt hepatic injuries during a 40-month period were reviewed. Complications and treatment of hepatic-related complications in patients not requiring laparotomy in the first 24 hours were identified.

RESULTS

Of 337 patients with a grade 3 to 5 injury, 230 (68%) were managed nonoperatively. There were 37 hepatic-related complications in 25 patients (11%); 63% (5 of 8) of patients with grade 5 injuries developed complications, 21% (19 of 92) of patients with grade 4 injuries, but only 1% (1 of 130) of patients with grade 3 injuries. Complications included bleeding in 13 patients managed by angioembolization (n = 12) and laparotomy (n = 1), liver abscesses in 2 patients managed with computed tomography-guided drainage (n = 2) and subsequent laparotomy (n = 1). In one patient with bleeding, hepatic necrosis followed surgical ligation of the right hepatic artery and required delayed hepatic lobectomy. Sixteen biliary complications were managed with endoscopic retrograde cholangiopancreatography and stenting (n = 7), drainage (n = 5), and laparoscopy (n = 4). Three patients had suspected abdominal sepsis and underwent a negative laparotomy, whereas an additional three patients underwent laparotomy for abdominal compartment syndrome.

CONCLUSION

Nonoperative management of high-grade liver injuries can be safely accomplished. Mortality is low; however, complications in grade 4 and 5 injuries should be anticipated and may require a combination of operative and nonoperative management strategies.

Moderne Diagnostik des Bauchtraumas

In case of suspected intra-abdominal injury, fast transport of the patient to a suitable hospital is of high priority. The initial clinical examination aims at identifying patients with potentially life-threatening bleeding that require emergency surgery. In patients with penetrating trauma, laparoscopy is favoured to exclude suspected perforation of the peritoneum. If a peritoneal perforation is identified, exploratory laparotomy is recommended to exclude or treat lacerations of the hollow viscus. Although clinical examination should be performed its sensitivity and specificity of up to 82% and 45%, respectively, are not sufficient as the sole screening method. For the further diagnostic workup, diagnostic peritoneal lavage has been completely replaced by abdominal ultrasound examination in Germany and many other countries. Focussing not only on the detection of free abdominal fluid but also searching for parenchymal organ lesions and performing repeated examinations increases accuracy up to 96%, with specificity of 99.8% and sensitivity of 72.1%. Computed abdominal tomography with a helical scanner with and without intravenous contrast media is currently the gold standard of imaging techniques to identify traumatic abdominal injuries. A sensitivity of 97.2% and specificity of 94.7% can be achieved. False negative findings must be expected with hollow organ injuries. Serial clinical and ultrasound examinations as well as lab testing in conjunction with repeated CT may help to identify such lesions. Increased intra-abdominal pressure (IAP) with consecutive abdominal compartment syndrome and multiple organ dysfunction is a delayed complication from conditions such as severe intra-abdominal bleeding, major bleeding from pelvic ring fractures, and profuse fluid resuscitation. The IAP should be measured routinely in patients at risk, and decompression laparotomy may be indicated with pressures of higher than 20 mmHg.

RESUSCITATION-INDUCED INTESTINAL EDEMA DECREASES THE STIFFNESS AND RESIDUAL STRESS OF THE INTESTINE

We have shown that acute edema impairs intestinal transit and we wanted to know whether this could be from changes in the physical characteristics of the intestine. Our hypothesis was that acute edema will change the physical characteristics of the intestine, which were measured by standardized engineering measures of elastic modulus, to determine stiffness and opening angle, and to determine residual stress. Rats were randomized to sham, mild edema (80 mL/ kg of normal saline resuscitation), and severe edema groups (80 mL/kg of normal saline resuscitation with intestinal venous hypertension). Segments of distal ileum were hung to a fixed point in a tissue bath and to a tensiometer and were stretched in increments of 1 mm, recording the new length and the corresponding force from the tensiometer to determine elastic modulus. Next, two transverse cuts were made yielding a 1- to 2-mm-thick ring-shaped segment of tissue and were then cut radially to open the ring. The opening angle was measured. Acute intestinal edema led to a decrease in transit, elastic modulus, and opening angle of the intestine in the absence of ischemic injury. Acute intestinal edema leads to a significant loss in stiffness and residual stress and is a plausible explanation for how acute edema impairs intestinal transit.

Inhibition of intestinal transit by resuscitation-induced gut edema is reversed by L-NIL

BACKGROUND

Post-resuscitation gut edema and associated gut dysfunction is a common and significant clinical problem that occurs after traumatic injury and shock. We have shown previously that gut edema without ischemia/reperfusion injury delays intestinal transit [1]. We hypothesized that gut edema increases expression of inducible nitric oxide synthase (iNOS) protein, and that selective iNOS inhibition using L-NIL reverses the delayed intestinal transit associated with gut edema.

MATERIALS AND METHODS

One hour prior to laparotomy, rats were pretreated with 10 mg/kg body weight of intraperitoneal L-NIL or saline vehicle and underwent 80 ml/kg body weight of 0.9% saline + superior mesenteric venous pressure elevation (Edema) or sham surgery (Sham). A duodenal catheter was placed to allow injection of a fluorescent dye for the measurement of intestinal transit. At 6 h, the small bowel was divided and the mean geometric center (MGC) of fluorescent dye was measured to determine transit. Ileum was harvested for histological assessment of mucosal injury, evaluation of iNOS protein expression by Western blotting, and MPO activity. Tissue water was determined using the wet-to-dry weight ratio to assess gut edema. Data are expressed as mean +/- SEM, n = 3-6 and * = P <0.05 using ANOVA.

RESULTS

Gut edema, expressed as increased wet-to-dry ratio, was associated with decreased intestinal transit and elevated iNOS protein expression. Pretreatment with l-NIL improved intestinal transit and decreased expression of iNOS protein without decreasing intestinal tissue water compared to edema animals. There was no difference in mucosal injury or MPO activity among groups.

CONCLUSION

Gut edema delays intestinal transit via an iNOS-mediated mechanism.