Temporal patterns of hemodynamics, oxygen transport, cytokine activity, and complement activity in the development of adult respiratory distress syndrome after severe injury

Complement as a vital nexus of the pathobiological connectome for acute respiratory distress syndrome: An emerging therapeutic target

The hallmark of acute respiratory distress syndrome (ARDS) pathobiology is unchecked inflammation-driven diffuse alveolar damage and alveolar-capillary barrier dysfunction. Currently, therapeutic interventions for ARDS remain largely limited to pulmonary-supportive strategies, and there is an unmet demand for pharmacologic therapies targeting the underlying pathology of ARDS in patients suffering from the illness. The complement cascade (ComC) plays an integral role in the regulation of both innate and adaptive immune responses. ComC activation can prime an overzealous cytokine storm and tissue/organ damage. The ARDS and acute lung injury (ALI) have an established relationship with early maladaptive ComC activation. In this review, we have collected evidence from the current studies linking ALI/ARDS with ComC dysregulation, focusing on elucidating the new emerging roles of the extracellular (canonical) and intracellular (non-canonical or complosome), ComC (complementome) in ALI/ARDS pathobiology, and highlighting complementome as a vital nexus of the pathobiological connectome for ALI/ARDS via its crosstalking with other systems of the immunome, DAMPome, PAMPome, coagulome, metabolome, and microbiome. We have also discussed the diagnostic/therapeutic potential and future direction of ALI/ARDS care with the ultimate goal of better defining mechanistic subtypes (endotypes and theratypes) through new methodologies in order to facilitate a more precise and effective complement-targeted therapy for treating these comorbidities. This information leads to support for a therapeutic anti-inflammatory strategy by targeting the ComC, where the arsenal of clinical-stage complement-specific drugs is available, especially for patients with ALI/ARDS due to COVID-19.

Absence of Stress Hyperglycemia Indicates the Most Severe Form of Blunt Liver Trauma

Background: Stress hyperglycemia is common in trauma patients. Increasing injury severity and hemorrhage trigger hepatic gluconeogenesis, glycogenolysis, peripheral and hepatic insulin resistance. Consequently, we expect glucose levels to rise with injury severity in liver, kidney and spleen injuries. In contrast, we hypothesized that in the most severe form of blunt liver injury, stress hyperglycemia may be absent despite critical injury and hemorrhage. Methods: All patients with documented liver, kidney or spleen injuries, treated at a university hospital between 2000 and 2020 were charted. Demographic, laboratory, radiological, surgical and other data were analyzed. Results: A total of 772 patients were included. In liver (n = 456), spleen (n = 375) and kidney (n = 152) trauma, an increase in injury severity past moderate to severe (according to the American Association for the Surgery of Trauma, AAST III-IV) was associated with a concomitant rise in blood glucose levels independent of the affected organ. While stress-induced hyperglycemia was even more pronounced in the most severe forms (AAST V) of spleen (median 10.7 mmol/L, p < 0.0001) and kidney injuries (median 10.6 mmol/L, p = 0.004), it was absent in AAST V liver injuries, where median blood glucose level even fell (5.6 mmol/L, p < 0.0001). Conclusions: Absence of stress hyperglycemia on hospital admission could be a sign of most severe liver injury (AAST V). Blood glucose should be considered an additional diagnostic criterion for grading liver injury.

Increased complement activation 3 to 6 h after trauma is a predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome: a prospective observational study

Background

Complement activation is a central mechanism in systemic inflammation and remote organ dysfunction following major trauma. Data on temporal changes of complement activation early after injury is largely missing. We aimed to describe in detail the kinetics of complement activation in individual trauma patients from admission to 10 days after injury, and the association with trauma characteristics and outcome.

Methods

In a prospective cohort of 136 trauma patients, plasma samples obtained with high time resolution (admission, 2, 4, 6, 8 h, and thereafter daily) were assessed for terminal complement complex (TCC). We studied individual TCC concentration curves and calculated a summary measure to obtain the accumulated TCC response 3 to 6 h after injury (TCC-AUC_3–6). Correlation analyses and multivariable linear regression analyses were used to explore associations between individual patients’ admission TCC, TCC-AUC_3–6, daily TCC during the intensive care unit stay, trauma characteristics, and predefined outcome measures.

Results

TCC concentration curves showed great variability in temporal shapes between individuals. However, the highest values were generally seen within the first 6 h after injury, before they subsided and remained elevated throughout the intensive care unit stay. Both admission TCC and TCC-AUC_3–6 correlated positively with New Injury Severity Score (Spearman’s rho, p-value 0.31, 0.0003 and 0.21, 0.02) and negatively with admission Base Excess (− 0.21, 0.02 and − 0.30, 0.001). Multivariable analyses confirmed that deranged physiology was an important predictor of complement activation. For patients without major head injury, admission TCC and TCC-AUC_3–6 were negatively associated with ventilator-free days. TCC-AUC_3–6 outperformed admission TCC as a predictor of Sequential Organ Failure Assessment score at day 0 and 4.

Conclusions

Complement activation 3 to 6 h after injury was a better predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome than admission TCC. Our data suggest that the greatest surge of complement activation is found within the first 6 h after injury, and we argue that this time period should be in focus in the design of future experimental studies and clinical trials using complement inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00286-3.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

Inflammation, Thrombosis, and Destruction: The Three-Headed Cerberus of Trauma- and SARS-CoV-2-Induced ARDS

Physical trauma can be considered an unrecognized "pandemic" because it can occur anywhere and affect anyone and represents a global burden. Following severe tissue trauma, patients frequently develop acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS) despite modern surgical and intensive care concepts. The underlying complex pathophysiology of life-threatening ALI/ARDS has been intensively studied in experimental and clinical settings. However, currently, the coronavirus family has become the focus of ALI/ARDS research because it represents an emerging global public health threat. The clinical presentation of the infection is highly heterogeneous, varying from a lack of symptoms to multiple organ dysfunction and mortality. In a particular subset of patients, the primary infection progresses rapidly to ALI and ARDS. The pathophysiological mechanisms triggering and driving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced ALI/ARDS are still poorly understood. Although it is also generally unknown whether insights from trauma-induced ARDS may be readily translated to SARS-CoV-2-associated ARDS, it was still recommended to treat coronavirus-positive patients with ALI/ARDS with standard protocols for ALI/ARDS. However, this strategy was questioned by clinical scientists, because it was documented that some severely hypoxic SARS-CoV-2-infected patients exhibited a normal respiratory system compliance, a phenomenon rarely observed in ARDS patients with another underlying etiology. Therefore, coronavirus-induced ARDS was defined as a specific ARDS phenotype, which accordingly requires an adjusted therapeutic approach. These suggestions reflect previous attempts of classifying ARDS into different phenotypes that might overall facilitate ARDS diagnosis and treatment. Based on the clinical data from ARDS patients, two major phenotypes have been proposed: hyper- and hypo-inflammatory. Here, we provide a comparative review of the pathophysiological pathway of trauma-/hemorrhagic shock-induced ARDS and coronavirus-induced ARDS, with an emphasis on the crucial key points in the pathogenesis of both these ARDS forms. Therefore, the manifold available data on trauma-/hemorrhagic shock-induced ARDS may help to better understand coronavirus-induced ARDS.

Diagnosis and treatment of acute pulmonary inflammation in critically ill patients: The role of inflammatory biomarkers

Pneumonia and acute respiratory distress syndrome are common and important causes of respiratory failure in the intensive care unit with a significant impact on morbidity, mortality and health care utilization despite early antimicrobial therapy and lung protective mechanical ventilation. Both clinical entities are characterized by acute pulmonary inflammation in response to direct or indirect lung injury. Adjunct anti-inflammatory treatment with corticosteroids is increasingly used, although the evidence for benefit is limited. The treatment decisions are based on radiographic, clinical and physiological variables without regards to inflammatory state. Current evidence suggests a role of biomarkers for the assessment of severity, and distinguishing sub-phenotypes (hyper-inflammatory versus hypo-inflammatory) with important prognostic and therapeutic implications. Although many inflammatory biomarkers have been studied the most common and of interest are C-reactive protein, procalcitonin, and pro-inflammatory cytokines including interleukin 6. While extensively studied as prognostic tools (prognostic enrichment), limited data are available for the role of biomarkers in determining appropriate initiation, timing and dosing of adjunct anti-inflammatory treatment (predictive enrichment).

Effect of Single Compared to Repeated Doses of Intravenous S(+) Ketamine on the Release of Pro-inflammatory Cytokines in Patients Undergoing Radical Prostatectomy

Background:

Radical prostatectomy is a major surgical procedure that is associated with marked inflammatory response and impairment of the immune system which may affect the postoperative outcome. The aim of this study was to evaluate the effect of preincision single or multiple doses of S(+) ketamine on the pro-inflammatory cytokines, namely tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6).

Patients and Methods:

This is a randomized controlled trial including 60 American Society of Anesthesiologists Physical Status I and II patients scheduled for radical prostatectomy under combined general-epidural anesthesia in Cairo university Teaching Hospital. Patients were randomly divided into three groups each of twenty patients: Group I received no S(+) ketamine (control group), Group II received S(+) ketamine as a single preincision dose, and Group III received preincision and repeated doses of S(+) ketamine. S(+) ketamine was injected as a single intravenous dose of 0.5 mg/kg in Group II and III, repeated as 0.2 mg/kg at 20 min interval until 30 min before the end of surgery.

Results:

The three groups were comparable in age, weight, and duration of the operation. The study also revealed that a single preincision dose of S(+) ketamine decreased TNF-α to reach 1027.04 ± 50.13 μ/ml and IL-6 to reach 506.89 ± 25.35 pg/ml whereas the repeated doses of S(+) ketamine decreased TNF-α to reach 905.64 ± 35065 μ/ml and IL-6 to reach 412.79 ± 16.5 pg/ml (P < 0.05).

Conclusion:

S(+) ketamine suppresses pro-inflammatory cytokine production, especially when given in repeated doses.

Nebulized C1-Esterase Inhibitor does not Reduce Pulmonary Complement Activation in Rats with Severe Streptococcus Pneumoniae Pneumonia

Complement activation plays an important role in the pathogenesis of pneumonia. We hypothesized that inhibition of the complement system in the lungs by repeated treatment with nebulized plasma-derived human C1-esterase inhibitor reduces pulmonary complement activation and subsequently attenuates lung injury and lung inflammation. This was investigated in a rat model of severe Streptococcus pneumoniae pneumonia. Rats were intra–tracheally challenged with S. pneumoniae to induce pneumonia. Nebulized C1-esterase inhibitor or saline (control animals) was repeatedly administered to rats, 30 min before induction of pneumonia and every 6 h thereafter. Rats were sacrificed 20 or 40 h after inoculation with bacteria. Brochoalveolar lavage fluid and lung tissue were obtained for measuring levels of complement activation (C4b/c), lung injury and inflammation. Induction of pneumonia was associated with pulmonary complement activation (C4b/c at 20 h 1.24 % [0.56–2.59] and at 40 h 2.08 % [0.98–5.12], compared to 0.50 % [0.07–0.59] and 0.03 % [0.03–0.03] in the healthy control animals). The functional fraction of C1-INH was detectable in BALF, but no effect was found on pulmonary complement activation (C4b/c at 20 h 0.73 % [0.16–1.93] and at 40 h 2.38 % [0.54–4.19]). Twenty hours after inoculation, nebulized C1-esterase inhibitor treatment reduced total histology score, but this effect was no longer seen at 40 h. Nebulized C1-esterase inhibitor did not affect other markers of lung injury or lung inflammation. In this negative experimental animal study, severe S. pneumoniae pneumonia in rats is associated with pulmonary complement activation. Repeated treatment with nebulized C1-esterase inhibitor, although successfully delivered to the lungs, does not affect pulmonary complement activation, lung inflammation or lung injury.

Predictive value of cytokines for developing complications after polytrauma

AIM: To investigate posttraumatic cytokine alterations and their value for predicting complications and mortality in polytraumatized patients.

METHODS: Studies on the use of specific cytokines to predict the development of complications and mortality were identified in MEDLINE, EMBASE, Web of Science and the Cochrane Library. Of included studies, relevant data were extracted and study quality was scored.

RESULTS: Forty-two studies published between 1988 and 2015 were identified, including 28 cohort studies and 14 “nested” case-control studies. Most studies investigated the cytokines interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor (TNF-α). IL-6 seems related to muliorgan dysfunction syndrome, multiorgan failure (MOF) and mortality; IL-8 appears altered in acute respiratory distress syndrome, MOF and mortality; IL-10 alterations seem to precede sepsis and MOF; and TNF-α seems related to MOF.

CONCLUSION: Cytokine secretion patterns appear to be different for patients developing complications when compared to patients with uneventful posttraumatic course. More research is needed to strengthen the evidence for clinical relevance of these cytokines.

The role of hormone replacement therapy in the intensive care management of deceased organ donors: a primer for nurses

Donation after brain death remains the primary contributor to the supply of organs available for transplantation in the United States. After brain death, both a surge of catecholamines and a dysregulation of the neurohormonal axis may result in hypotension, decreased organ perfusion, and reduced viability of organs to be transplanted. Hormone replacement therapy is widely used to maintain organ perfusion and has been shown to increase the number of organs procured. This article reviews the literature and mechanisms supporting the use of hormone replacement therapy in brain-dead organ donors and provides clinicians with information regarding the administration, monitoring, and preparation of thyroid hormone, arginine vasopressin, and corticosteroids.

Plasma-derived human C1-esterase inhibitor does not prevent mechanical ventilation-induced pulmonary complement activation in a rat model of Streptococcus pneumoniae pneumonia

Mechanical ventilation has the potential to cause lung injury, and the role of complement activation herein is uncertain. We hypothesized that inhibition of the complement cascade by administration of plasma-derived human C1-esterase inhibitor (C1-INH) prevents ventilation-induced pulmonary complement activation, and as such attenuates lung inflammation and lung injury in a rat model of Streptococcus pneumoniae pneumonia. Forty hours after intratracheal challenge with S. pneumoniae causing pneumonia rats were subjected to ventilation with lower tidal volumes and positive end-expiratory pressure (PEEP) or high tidal volumes without PEEP, after an intravenous bolus of C1-INH (200 U/kg) or placebo (saline). After 4 h of ventilation blood, broncho-alveolar lavage fluid and lung tissue were collected. Non-ventilated rats with S. pneumoniae pneumonia served as controls. While ventilation with lower tidal volumes and PEEP slightly amplified pneumonia-induced complement activation in the lungs, ventilation with higher tidal volumes without PEEP augmented local complement activation more strongly. Systemic pre-treatment with C1-INH, however, failed to alter ventilation-induced complement activation with both ventilation strategies. In accordance, lung inflammation and lung injury were not affected by pre-treatment with C1-INH, neither in rats ventilated with lower tidal volumes and PEEP, nor rats ventilated with high tidal volumes without PEEP. Ventilation augments pulmonary complement activation in a rat model of S. pneumoniae pneumonia. Systemic administration of C1-INH, however, does not attenuate ventilation-induced complement activation, lung inflammation, and lung injury.

Biomarkers in acute respiratory distress syndrome

PURPOSE OF REVIEW

The article provides an overview of efforts to identify and validate biomarkers in acute respiratory distress syndrome (ARDS) and a discussion of the challenges confronting researchers in this area.

RECENT FINDINGS

Although various putative biomarkers have been investigated in ARDS, the data have been largely disappointing and the 'troponin' of ARDS remains elusive. Establishing a relationship between measurable biological processes and clinical outcomes is vital to advancing clinical trials in ARDS and expanding our arsenal of treatments for this complex syndrome.

SUMMARY

This article summarizes the current status of ARDS biomarker research and provides a framework for future investigation.

Peri-operative changes in serum immune markers after trauma: a systematic review

INTRODUCTION

Surgery is a posttraumatic immune stimulus which contributes to the systemic inflammatory response syndrome and multiple organ failure (MOF). Serum markers may facilitate post-injury immune monitoring, predict complications and guide the timing of surgery.

AIM

To evaluate whether immune markers increase after surgery in trauma patients, if this is affected by the timing of surgery, and whether immune markers correlate with clinical outcomes.

PATIENTS AND METHODS

Systematic review of MEDLINE, Cochrane and EMBASE using a combination of keywords including trauma, biological markers, immune monitoring, and surgical procedures. The last search was performed on 26/11/13. The search considered English language studies enrolling adult trauma patients. Outcomes were perioperative immune markers plus clinical outcomes including mortality, MOF, sepsis.

RESULTS

1612 Articles were identified using the search strategy. 1548 Articles were excluded by title and 40 excluded by abstract, leaving 24 articles for full text review. Of these articles, fifteen studies were eligible for study inclusion. The disparity in interventions and outcome measures precluded combined statistical analysis. The surgical intervention studied was mostly intramedullary nailing of long bone fractures. All articles described a postoperative increase in at least one marker. Interleukin (IL)-6 and IL-10 were consistently elevated and tested in the greatest number of patients. Many studies did not correlate markers with clinical outcomes and few significant associations were demonstrated. Two studies considered the timing of surgery and showed greater increase in IL-6 after "early" surgery, though definitions of timing were dissimilar.

DISCUSSION

An increase in posttraumatic serum cytokines has been demonstrated after surgery, but without consistent clinical associations. The timing of surgery may modulate this increase. Future research directions include confirmation of findings in larger populations, clarifying clinical associations, and evaluation of other surgical interventions.

Peripheral cytokines as a chemical mediator for postconcussion like sickness behaviour in trauma and perioperative patients: literature review

Besides brain injury and systemic infection, cognitive and concussion like sickness behaviour is associated with muscular trauma and perioperative patients, which represents a major obstacle to daily activities and rehabilitation. The neuroinflammatory response triggers glial activation and consequently the release of proinflammatory cytokines within the hippocampus. We review clinical studies that have investigated neurocognitive and psychosomatic symptoms related to muscular trauma and in perioperative conditions. These include impaired attention and executive and general cognitive functioning. The purpose of this literature review is to focus on the systemic inflammation and the role of proinflammatory cytokines IL1, IL6,and TNF and other inflammatory mediators which mediates the cognitive impairment and induces sickness behaviour. Moreover, this review will also help to determine if some patients could have long-term cognitive changes associated with musculoskeletal injuries or as a consequence of surgery and thereby will lead to efforts in reducing that risk.

The use of regional cerebral oximetry monitoring during controlled hypotension: a case series

Regional cerebral oximetry monitoring was used to guide nitroglycerin infusion and IV fluid administration during controlled hypotension in order to optimize each individual patient's mean arterial pressure in a series of 20 consecutive patients who underwent major open urological or abdominal surgery. Although controlled hypotension offers a definite benefit in patients undergoing complex surgery where blood loss will be elevated or would severely compromise the surgical field, it is not without risk as low arterial pressure may compromise tissue perfusion and promote ischemia. In this case series, despite an average mean arterial pressure decrease of 19.5 % (p < 0.001), cerebral oximetry values increased by an average of 22.7 % (p < 0.001) after the nitroglycerin infusion had been initiated (220 mcg/min average). Patients received an average of 3.15L crystalloid and 437 ml albumin in fluid resuscitation.

Early alveolar and systemic mediator release in patients at different risks for ARDS after multiple trauma

Alveolar IL-8 has been reported to early identify patients at-risk to develop ARDS. However, it remains unknown how alveolar IL-8 is related to pulmonary and systemic inflammation in patients predisposed for ARDS. We studied 24 patients 2-6h after multiple trauma. Patients with IL-8 >200 pg/ml in bronchoalveolar lavage (BAL) were assigned to the group at high risk for ARDS (H, n = 8) and patients with BAL IL-8 <200 pg/ml to the group at low risk for ARDS (L, n = 16). ARDS developed within 24h after trauma in 5 patients at high and at least after 1 week in 2 patients at low risk for ARDS (p = 0.003). High-risk patients had also increased BAL IL-6, TNF-α, IL-1β, IL-10 and IL-1ra levels (p<0.05). BAL neutrophil counts did not differ between patient groups (H vs. L, 12% (3-73%) vs. 6% (2-32%), p = 0.1) but correlated significantly with BAL IL-8, IL-6 and IL-1ra. High-risk patients had increased plasma levels of pro- but not anti-inflammatory mediators. The enhanced alveolar and systemic inflammation associated with alveolar IL-8 release should be considered to identify high-risk patients for pulmonary complications after multiple trauma to adjust surgical and other treatment strategies to the individual risk profile.

Reduced Capacity of Whole Blood Leucocytes to Express Tumour Necrosis Factor-α and Interleukin-10 following Major Orthopaedic Surgery

BACKGROUND

Severe trauma is a challenge to the immune response and may cause reduced immune capacity. As a marker of decreased cellular activity, studies with ex vivo lipopolysaccharide (LPS) stimulation of whole blood or isolated mononuclear cells from injured patients have revealed reduced production of inflammatory cytokines. To gain further insight into immune alterations in orthopaedic surgery, we studied LPS-induced tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 in whole blood of patients during peri- and postoperative phases of total hip replacement.

METHODS

Four females and 3 males undergoing elective total hip replacement were included in the study. Ex vivo LPS-induced TNF-alpha and IL-10 were measured in a whole blood assay before, during and at 1 and 6 days after operation. In addition, the counts of white blood cells were determined.

RESULTS

During the operation, there were significant reductions in the number of monocytes, but at day 1 and 6 after surgery, there were significant increases as compared to the levels before surgery. The capacity of whole blood to express TNF-alpha and IL-10 did not change significantly during the operation and the following postoperative day. At day 6, however, there were significant reductions in expression of both TNF-alpha and IL-10 as compared to the levels before the operation. In relation to the values of monocytes, there was a significant reduction in the expression of TNF-alpha also at day 1 after operation.

CONCLUSION

Our data indicate that in the course of at least 6 days after a major orthopaedic trauma, there is suppression of the whole blood capacity to express the inflammatory cytokine TNF-alpha and the anti-inflammatory cytokine IL-10 when exposed to LPS. During this time, then, the patient is particular susceptible to septic complications.

Postoperative serum attenuates LPS-induced release of TNF-alpha in orthopaedic surgery

Studies with ex vivo stimulation of whole blood samples from injured patients have revealed a diminished production capacity for a broad range of secretory products, including inflammatory cytokines. Recent interest has focused on the release of mediators in serum that depress the cell-mediated immune response following trauma. The involvement of the lipid mediator prostaglandin E2 (PGE2) has been assumed because it is a potent endogenous immunosuppressor. In the present study, we tested the hypothesis that inhibitory substances circulating in the patient's serum after a major musculoskeletal trauma might impair leukocyte function by evaluating the effect of such serum on cytokine release in a whole blood model. Six females and three males undergoing elective total hip replacement were included in the study. Ex vivo LPS-induced TNF-alpha and IL-10 were measured in whole blood sampled preoperatively and added serum taken before, at the end of operation, and at postoperative days 1 and 6 with saline as negative control. LPS induced significant releases of TNF-alpha and IL-10 in whole blood. Addition of preoperative, postoperative, and day-1 postoperative serum did not alter the LPS-induced release of TNF-alpha as compared to saline. In the presence of serum from postoperative day 6, however, the expression of TNF-alpha was significantly reduced as compared to saline and preoperative serum (p = 0.021 and 0.008, respectively). Neither of the serum samples altered the release of IL-10. PGE2 was significantly (p = 0.008) increased in serum at postoperative day 6 as compared to preoperative levels. In conclusion, these data show that at day 6 after major orthopaedic surgery, the patient serum contained activity that inhibited ex vivo LPS-induced TNF-alpha release. The potent TNF-alpha inhibitory activity found at day 6 after injury correlated with increased levels of PGE2 and indicates cell-mediated hyporesponsiveness to a second stimulus.

Relationships between markers of inflammation, severity of injury, and clinical outcomes in hemorrhagic shock

This study was performed to investigate the relationships between markers of inflammation in serum (interleukin-6 [IL-6], interleukin-10 [IL-10], and granulocyte elastase [GE]), severity of injury, and clinical outcomes, and to evaluate the predictive value of these markers for major complications and mortality. This study, which was conducted between August 2003 and May 2005, examined patients older than 16 y who were admitted to the Emergency Unit of the Uludag University Medical School within 12 h after trauma, and who had traumatic hemorrhagic shock (THS) at admission. Three groups were established: the THS group (n=20), the pure hemorrhagic shock (PHS) group (n=20), and the healthy control group (n=20). Demographic data were recorded for all subjects, and blood samples were taken for lactate, base excess, GE, IL-6, and IL-10 measurements. The Glasgow Coma Score, the Revised Trauma Score, the Injury Severity Score, the New Injury Severity Score, and the Trauma Score-Injury Severity Score were calculated; complications and final clinical outcomes were monitored. A total of 35 men and 25 women were included in the study; mean patient age was 41+/-17 y. In the THS group, scores were as follows: Revised Trauma Score, 10.2+/-2.2; Trauma Score-Injury Severity Score, 0.86+/-0.2; Injury Severity Score, 24.8+/-9.0; and New Injury Severity Score, 32.7+/-9.0. IL-6, IL-10, lactate, and base excess levels in the THS group were significantly higher than those in the PHS and healthy control groups. The serum GE level of the THS group was significantly higher than that of the healthy control group, but it did not differ significantly from that of the PHS group. Complications such as sepsis, acute respiratory distress syndrome, and multiple organ failure occurred in 50% of the THS group and in 20% of the PHS group. Mortality was 30% in the THS group and 10% in the PHS group. In the THS group, no significant differences were noted between markers of inflammation and trauma scores of patients who died and those who survived. The investigators concluded that although the levels of markers of inflammation increased in THS patients, they were inadequate for predicting mortality and the development of complications such as acute respiratory distress syndrome, multiple organ failure, and sepsis. A larger study based on the use of serial marker measurements is warranted.

Tumor necrosis factor-alpha from macrophages enhances LPS-induced clara cell expression of keratinocyte-derived chemokine

Tumor necrosis factor (TNF)-alpha is a cytokine produced by alveolar macrophages in response to LPS in the lung. Clara cells are bronchiolar epithelial cells that produce a variety of proinflammatory cytokines in response to LPS but not to TNF-alpha. In this study, we examined whether TNF-alpha affects Clara cell cytokine production in the setting of LPS stimulation. Using a transformed murine Clara cell line (C22), we observed that both LPS and TNF-alpha induced production of keratinocyte-derived chemokine (KC) and monocyte chemoattractant protein (MCP)-1. We also found that simultaneous LPS and TNF-alpha stimulation is synergistic for KC production, but additive for MCP-1 production. By using a Transwell coculture system of RAW264.7 macrophages and Clara cells isolated from C57Bl/6 mice, we found that macrophages produce a soluble factor that enhances Clara cell KC production in response to LPS. Cocultures of Clara cells from mice deficient in TNF-alpha receptors with RAW264.7 macrophages demonstrated that the effect of macrophages on Clara cells is mediated primarily via TNF-alpha. To determine whether these findings occur in vivo, we treated wild-type and TNF receptor-deficient mice intratracheally with LPS and examined the expression of KC. LPS-treated, TNF receptor-deficient mice showed much less KC mRNA in airway epithelial cells compared with wild-type mice. In contrast, a similar number of KC-expressing cells was seen in the lung periphery. Thus, upregulation of KC by Clara cells in the setting of LPS stimulation is largely dependent on TNF-alpha originating from alveolar macrophages. These findings shed light on macrophage-Clara cell interactions in regulating the pulmonary inflammatory response to LPS.

CHEMICALLY MODIFIED TETRACYCLINE (COL-3) IMPROVES SURVIVAL IF GIVEN 12 BUT NOT 24 HOURS AFTER CECAL LIGATION AND PUNCTURE

Sepsis can result in excessive and maladaptive inflammation that is responsible for more than 215,00 deaths per year in the United State alone. Current strategies for reducing the morbidity and mortality associated with sepsis rely on treatment of the syndrome rather than prophylaxis. We have been investigating a modified tetracycline, COL-3, which can be given prophylactically to patients at high risk for developing sepsis. Our group has shown that COL-3 is very effect at preventing the sequelae of sepsis if given before or immediately after injury in both rat and porcine sepsis models. In this study, we wanted to determine the "treatment window" for COL-3 after injury at which it remains protective. Sepsis was induced by cecal ligation and puncture (CLP). Rats were anesthetized and placed into five groups: CLP (n = 20) = CLP without COL-3, sham (n = 5) = surgery without CLP or COL-3, COL3@6h (n = 10) = COL-3 given by gavage 6 h after CLP, COL3@12h (n = 10) = COL-3 given by gavage 12 h after CLP, and COL3@24h (n = 20) = COL-3 given by gavage 24 h after CLP. COL-3 that was given at 6 and 12 h after CLP significantly improved survival as compared with the CLP and the CLP@24h groups. Improved survival was associated with a significant improvement in lung pathology assessed morphologically. These data suggest that COL-3 can be given up to 12 h after trauma and remain effective.

Enhanced neutrophil migratory activity following major blunt trauma

BACKGROUND

Neutrophil migration into the lung is a critical, but poorly understood step in the pathogenesis of post-traumatic, acute respiratory distress syndrome (ARDS). We investigated changes in interleukin-8 (IL-8) mediated neutrophil migration and associated changes in receptor expression, of the IL-8 receptors CXCR1, the integrins CD11b/CD18 and platelet endothelial cell adhesion molecule-1 (PECAM-1) in patients sustaining major trauma.

METHODS

Eleven patients with major trauma, injury severity score (ISS), median 22 (range 18-41), were followed prospectively. Eleven normal volunteers were used as controls. Blood samples were obtained within 4+/-2 h of injury, at 24 h, day 3 and day 5. Neutrophils migration was assessed by an in vitro IL-8 assay and neutrophil surface receptor expression by FACS analysis.

RESULTS

IL-8 mediated neutrophil migration was significantly increased on admission following major trauma and remained elevated for 3 days (p<0.05). This was associated with up-regulation of CXCR1 (p<0.01) and down-regulation of PECAM-1 (p<0.05). CD11b and CD18 although initially unchanged, became down-regulated on day 3 (p<0.05).

CONCLUSIONS

These data show that major trauma primes circulating neutrophils for increased migration in response to IL-8. This response is sustained for 72 h and is associated with changes in neutrophil surface receptor expression.

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.

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.

Long-term stable cultures of rat hepatocytes: an in vitro model to study acute and chronic hepatic inflammation

Engineered tissues provide an opportunity to investigate important physiological processes difficult to study in whole perfused organs and animal models. For example, a hepatocyte culture model consisting of rat hepatocytes cultured in a collagen sandwich configuration, which exhibits stable differentiated liver-specific functions, may be useful to investigate liver pathophysiology. To investigate systemic inflammation-related hepatic failure, we chronically exposed hepatocytes to the inflammatory mediators interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) for up to 4 weeks. IL-6 (2.5 ng/mL) transiently suppressed albumin (-90%) and chronically increased fibrinogen (+6-fold) production. IL-6 inhibited urea synthesis at 2.5 ng/mL and stimulated it at 0.025 ng/mL. IL-1beta (10 ng/mL) inhibited albumin (-90%), urea (-40 to 50%), and IL-6-stimulated fibrinogen (-90%) secretion. The inhibitory effect of IL-1beta on urea secretion was dose-dependent. Furthermore, IL-1beta transiently stimulated nitric oxide (NO) synthesis; however, NO did not mediate the effect of IL-1beta on albumin and fibrinogen production, and played a minor role in IL-1beta-mediated urea synthesis suppression. In conclusion, IL-1beta and IL-6 exert, via a direct effect on hepatocytes, long-term inhibitory effects on hepatic functions that are potentially important for the survival of the host, which may contribute to hepatic dysfunction in prolonged inflammatory states.

Prospectively validated prediction of physiologic variables and organ failure in septic patients: The Systemic Mediator Associated Response Test (SMART)

OBJECTIVE

Conventional outcomes research provides only percentage risk of such end points as mortality rate, utilization of resources, and/or broad groupings of multiple organ system dysfunction. These prognostications generally are not applicable to individual patients. The purpose of the present study was to determine whether the Systemic Mediator Associated Response Test (SMART) methodology could identify interactions among demographics, physiologic variables, standard hospital laboratory tests, and circulating cytokine concentrations that predicted continuous and dichotomous dependent clinical variables, in advance, in individual patients with severe sepsis and septic shock, and whether these independent variables could be integrated into prospectively validated predictive models.

DESIGN

Data review and multivariate stepwise logistic regression.

SETTING

University research laboratory.

PATIENTS

Three hundred three patients with severe sepsis or septic shock who comprised the placebo arm of a multiple-institution clinical trial, who were randomly separated into a model building training cohort (n = 200) and a predictive cohort (n = 103).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

From baseline data and baseline plus serial input, including patient demographics, hospital laboratory tests, and plasma concentrations of interleukin-6, interleukin-8, and granulocyte colony stimulating factor, multiple regression models were developed that predicted clinically important continuous dependent variables quantitatively, in individual patients. Multivariate stepwise logistic regression was used to develop models that prognosticated dichotomous dependent end points. Data from individual patients in the predictive cohort were inserted into each predictive model for each day, with prospective validation accomplished by simple linear regression of individual predicted vs. observed values for continuous dependent variables, and by establishing the receiver operator characteristics area under the curve for logistic regression models that predicted dichotomous end points. Of SMART models for continuous dependent variables, 100 of 143 (70%) were validated at r values >.7 through day 3, and 184 of 259 (71%) above r =.5 through day 5. SMART predictions of dichotomous end points achieved receiver operator characteristics areas under the curve >.7 for up to 84% of the equations in the first week. Many SMART models for both continuous and dichotomous dependent variables were validated at clinically useful levels of accuracy as far as 28 days after baseline.

CONCLUSIONS

SMART integration of demographics, bedside physiology, hospital laboratory tests, and circulating cytokines predicts organ failure and physiologic function indicators in individual patients with severe sepsis and septic shock.

Predictive value of microalbuminuria in medical ICU patients: results of a pilot study

STUDY OBJECTIVES

To evaluate the predictive value of microalbuminuria in the development of acute respiratory failure (ARF) and multiple organ failure (MOF) in ICU patients.

DESIGN

Prospective, observational study.

SETTING

A 31-bed, mixed medicosurgical ICU in a university hospital.

PATIENTS

All adult medical patients admitted to the ICU over a 2-month period, except those receiving nephrotoxic drugs, or those with urologic trauma resulting in frank hematuria or urinary infection, or with existing chronic renal disease (serum creatinine level > or 2.0 mg/dL).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Urinary samples for microalbumin measurement were collected at hospital admission and at 8, 24, 48, 72, 96, and 120 h after hospital admission. The severity of illness was assessed by the APACHE (acute physiology and chronic health evaluation) II score calculated on the first ICU day, and the degree of organ dysfunction was assessed using the sequential organ failure assessment (SOFA) score. Acute respiratory failure (ARF) was defined as a SOFA respiratory score > or = 3. Patients were separated into two groups according to the trend in microalbuminuria levels over the first 48 h: patients in group 1 had increasing microalbuminuria levels, and patients in group 2 had decreasing microalbuminuria levels. Group 1 included 14 patients in whom microalbuminuria levels increased from 5.2 +/- 2.0 to 19.0 +/- 3.0 mg/dL. Group 2 included 26 patients in whom microalbuminuria levels decreased from 16.4 +/- 4.0 to 7.8 +/- 3.0 mg/dL. The hospital mortality rate was 43% in group 1 and 15% in group 2 (p < 0.05). The APACHE II score and the SOFA score were higher in group 1 than in group 2. The negative predictive value of increasing microalbuminuria was 100% for the development of ARF and 96% for MOF; the positive predictive value of increasing microalbuminuria was 57% for the development of ARF and 50% for MOF.

CONCLUSIONS

Accurate identification of patients destined for ARF and MOF development may enable therapeutic strategies to be applied to limit the disease process. Trend analysis of urinary albumin excretion over the first 48 h of an ICU admission may provide a useful means of identifying such patients. Additional studies need to be performed in larger, mixed patient populations to confirm these findings.

The immunomodulatory effects of prolonged intravenous infusion of propofol versus midazolam in critically ill surgical patients

Both propofol and midazolam are known to inhibit immune function. The aim of this study was to investigate cytokine production in critically ill surgical patients as early markers of immune response to prolonged infusion of propofol and midazolam. The study enrolled 40 elective patients who were to receive long-term sedation for more than 2 days. Patients were randomly allocated to one of two equally sized groups. Central venous blood samples for measurement of interleukin-1beta (IL-1beta), interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were drawn prior to the start and after 48 h of infusion. After 48 h, propofol caused significant increases in IL-1beta (24%), IL-6 (23%) and TNF-alpha (4.8 times) levels, while midazolam caused significant decreases in IL-1beta (21%), IL-6 (21%) and TNF-alpha (19%). Both agents caused significant decreases in IL-8 levels (propofol: 30%, midazolam: 48%, p < 0.05). Propofol caused significant decreases in IL-2 levels (68%, p < 0.001) but increases in IFN-gamma (30%, p < 0.05), whereas there was no significant change with midazolam compared with the pre-infusion level. In conclusion, during 48 h of continuous infusion, propofol stimulated, while midazolam suppressed, the production of the pro-inflammatory cytokines IL-1beta, IL-6 and TNF-alpha, and both caused suppression of IL-8 production. Propofol inhibited IL-2 production and stimulated IFN-gamma production, whereas midazolam failed to do so. Therefore, sedative agents may have clinical implications in high-risk and immunocompromised patients.

Metabolic correlates of oxygen debt predict posttrauma early acute respiratory distress syndrome and the related cytokine response

BACKGROUND

The purpose of this study was to quantify the relationship between negative base excess (base deficit) and lactate as correlates of oxygen debt and the probability of the early acute respiratory distress syndrome (ARDS) response and with regard to the mediator and metabolic response characteristic of this disease.

METHODS

Eighty patients with multiple trauma were studied (514 samples) during their intensive care unit courses (Injury Severity Score 27.6+/-8.8, 36% deaths). Simultaneous samples of arterial base excess and lactate as correlates of oxygen debt, and enzyme-linked immunosorbent assay-measured mixed venous cytokines were obtained daily. At each sample period, the patient was categorized as having ARDS or non-ARDS.

RESULTS

Twenty-nine patients (36%; 19 deaths) developed ARDS over the period studied: 17 in postinjury days 1 to 4 (EARLY ARDS) and 12 in postinjury days 5 or later (LATE ARDS). Patients subsequently developing ARDS had evidence of ischemic acidosis on or within the first 24 hours after hospital admission (lower base excess -7.1 mmol/L and higher lactate 5.2 mmol/L in ARDS versus base excess -3.8 mmol/L and lactate 3.6 mmol/L in non-ARDS; p < 0.05). Patients with EARLY ARDS showed even lower (p < 0.05) initial 24 hour mean base excess and higher lactate (base excess -9.1 mmol/L and lactate 6.4 mmol/L) compared with LATE ARDS (base excess -4.3 mmol/L and lactate 3.3 mmol/L). In EARLY ARDS, this degree of ischemic acidosis was followed by a greater mean IL-6 response in the postinjury days 1 to 4 (323 pg/mL) compared with the LATE ARDS response (141 pg/mL) (p < 0.05) or compared with the non-ARDS IL-6 response (67 pg/mL; p < 0.001). In addition, in EARLY ARDS, mean IL-8 levels in postinjury days 1 to 4 (264 pg/mL) were higher than in LATE ARDS (168 pg/mL) (p < 0.05) and the mean IL-1 response in postinjury days 1 to 4 of EARLY ARDS (65 pg/mL) was greater than non-ARDS (32 pg/mL) (p < 0.05). Derivation of probability curves suggests a critical threshold of base excess -6.6 mmol/L or greater for an increased risk of EARLY ARDS.

CONCLUSION

These data suggest that the maximum posttrauma oxygen debt (quantified by the ischemia correlates of negative base excess and lactate) is a critical primary determinant of the later fulminant autoinflammatory EARLY ARDS response mediated by the host's endogenous cytokine mediators.

Phase I trial of the recombinant soluble complement receptor 1 in acute lung injury and acute respiratory distress syndrome

OBJECTIVE

To determine the safety, pharmacokinetics, biological effects, and immunogenicity of recombinant soluble complement receptor 1 (TP10) in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).

DESIGN

Open label, ascending dosage, phase I trial.

SETTING

Two academic teaching hospitals.

PATIENTS

A total of 24 patients diagnosed with ALI/ARDS.

INTERVENTION

A single, 30-min intravenous infusion of 0.1, 0.3, 1, 3, or 10 mg/kg TP10.

MEASUREMENTS AND MAIN RESULTS

Serum levels of TP10 increased in proportion to the dose. Mean variable estimates (+/-SD) were half-life of disposition 69.7 +/- 39.7 hrs, plasma clearance 2.39 +/- 1.32 mL/hr/kg, and volume of distribution 190.6 +/- 135.0 mL/kg. Inhibition of complement activity, measured by CH50, was significant for the interaction of dose and time (p = .024). The C3a levels demonstrated a trend for dose which did not reach statistical significance (p = .090) and soluble C5b-9 levels were significant only for dose (p = .023). As expected by the proposed physiologic mechanism, C4a levels were not affected by TP10, dose, or time. The overall mortality rate was 33%. Neither the type nor the frequency rate of specific adverse events were substantially different between dose groups. Seven adverse events in four patients were thought to be possibly related to TP10.

CONCLUSIONS

TP10 has a half-life of approximately 70 hrs and at doses > or =1 mg/kg, significantly inhibits complement activity at the levels of C3 and C5 in patients with ALI/ARDS. Complement inhibition was more prolonged over time with TP10 doses of 3 and 10 mg/kg. TP10 appears to be safe at the doses tested. Further studies will be required to completely assess the impact of TP10 on pathophysiology and clinical outcome in patients with ALI/ARDS.

C3a and C5a enhance granulocyte adhesion to endothelial and epithelial cell monolayers: epithelial and endothelial priming is required for C3a-induced eosinophil adhesion

Effects of the anaphylatoxins C3a and C5a on eosinophil and neutrophil adhesion to HUVEC and to primary culture human bronchial epithelial cells (HBEC) were investigated. Activities on both leukocytes and on structural cells were examined. C3a upregulated beta2 integrin expression and caused shedding of L-selectin on eosinophils, but had no effect on neutrophil adhesion molecule expression. C5a upregulated beta2 integrins and caused shedding of L-selectin on both eosinophils and neutrophils. The potency of C5a was equivalent on both cell types; however, the magnitude of the changes in each of these adhesion molecules was significantly greater in neutrophils than eosinophils. Neither C3a nor C5a altered expression of ICAM-1, VCAM-1, E-selectin or P-selectin on either HUVEC or HBEC. C5a induced adhesion of both neutrophils and eosinophils to unstimulated HUVEC or HBEC, and adhesion was further enhanced when HUVEC and HBEC were "primed" with TNF-alpha and IFN-gamma, respectively. C3a failed to enhance adhesion of either eosinophils or neutrophils to unprimed HUVEC or HBEC, and enhanced only eosinophil adhesion to cytokine-primed HUVEC or HBEC. Similar to C3a, C3a(desArg) and a C3a-analog peptide E7 also enhanced eosinophil adhesion only to cytokine-primed HUVEC and HBEC. These results support the traditional view of anaphylatoxins as leukocyte-specific mediators. The specificity of C3a for eosinophils implicates this molecule as a potential participant in allergic inflammation. The pro-adhesive effects of C3a(desArg) suggest that this molecule, previously characterized as a spasmogenically inactive derivative of C3a, may also alter leukocyte dynamics and migration. Finally, activation of endothelium may represent an important control mechanism for C3a-mediated adhesion preventing unchecked eosinophil adhesion to uninflamed systemic vasculature.

Release of proinflammatory cytokines by mitogen-stimulated peripheral blood mononuclear cells from critically ill multiple-trauma victims

This study investigated the alterations in circulating proinflammatory cytokines and cytokine production by peripheral blood mononuclear cells (PBMCs) in response to lipopolysaccharide (LPS) or phytohemagglutinin (PHA) after severe trauma. Plasma and PBMCs were collected from 17 severely injured trauma patients and 10 healthy subjects. Plasma was stored at -80 degrees C and analyzed for cytokines. Isolated PBMCs from each subject were stimulated with LPS or PHA and incubated at 5% CO2 for 24 hours. Supernatants were collected and analyzed for cytokines. There was no significant change in the plasma concentration of free TNF-alpha and IL-1beta between healthy subjects and trauma patients. Plasma IL-6, total TNF-alpha, and total IL-1beta were significantly increased in severely traumatized patients compared with healthy control subjects. PBMCs from trauma patients produced higher levels of TNF-alpha in response to LPS but it showed no significant change in IL-1beta and IL-6 production in response to PHA or LPS in comparison to PBMCs from control subjects. We conclude that severe trauma results in a significant increase in plasma proinflammatory cytokine IL-6. Free TNF-alpha and IL-1beta in plasma remain at levels comparable to those in uninjured controls, while plasma free IL-6 levels in trauma patients remain high. Serious injury is associated with an enhanced production of TNF-alpha by PBMCs stimulated with LPS.

Ketamine suppresses proinflammatory cytokine production in human whole blood in vitro

The production of proinflammatory cytokines, such as tumor necrosis factor (TNF) a, interleukin (IL)-6, and IL-8, increases in patients with sepsis; marked production causes organ failure and septic shock. We previously reported that ketamine suppressed lipopolysaccharide (LPS)-induced TNF-alpha production in mice. However, there are no reports on the effect of ketamine on cytokine production in human whole blood. Therefore, in this study, we investigated the efficacy of ketamine on LPS-induced TNF-alpha, IL-6, and IL-8 production and recombinant human (rh) TNF-a-induced IL-6 and IL-8 production in human whole blood. After adding different doses of ketamine to whole blood, the blood was stimulated with LPS or rhTNF. After incubation, the plasma TNF-alpha activity and IL-6 and IL-8 concentrations were measured using the L929 cell cytotoxic assay or an enzyme-linked immunoassay. Ketamine significantly suppressed LPS-induced TNF-alpha production at concentrations >20 microg/mL. At concentrations >100 microg/mL, ketamine also significantly suppressed both LPS-induced and rhTNF-induced IL-6 and IL-8 production. In this study, we demonstrated that ketamine directly inhibits the production of proinflammatory cytokines such as TNF-alpha, IL-6, and IL-8 in human whole blood.

IMPLICATIONS

We found that ketamine suppressed lipopolysaccharide-induced tumor necrosis factor alpha, interleukin (IL)-6, and IL-8 production and recombinant human tumor necrosis factor-induced IL-6 and IL-8 production in human whole blood. Ketamine directly suppresses proinflammatory cytokine production.

Intramedullary pressure and bone marrow fat extravasation in reamed and unreamed femoral nailing

This study was designed to investigate whether intramedullary pressure and embolization of bone marrow fat are different in unreamed compared with conventional reamed femoral nailing in vivo. In a baboon model, the femoral shaft was stabilized with interlocking nailing after a midshaft osteotomy. Intramedullary pressure was measured in the distal femoral shaft fragment at the supracondylar region. Extravasation of bone marrow fat was determined by the modified Gurd test (range: 0-5) with blood samples from the vena cava inferior. Data were monitored in eight unreamed and eight reamed intramedullary femoral nailing procedures. Intramedullary pressure increased in the unreamed group to 76 +/- 25 mm Hg (10.1 +/- 3.3 kPa) during insertion of 7-mm nails and in the reamed group to 879 +/- 44 mm Hg (117.2 +/- 5.9 kPa) during reaming of the medullary cavity. Insertion of 9-mm nails after the medullary cavity had been reamed to 10 mm produced an intramedullary pressure of 254 +/- 94 mm Hg (33.9 +/- 12.5 kPa) (p < 0.05). Fat extravasation in the unreamed group was recorded with a score of 2.9 +/- 0.4 for the Gurd test during nailing with 7-mm nails, whereas in the reamed group significantly more fat extravasation was noticed during the reaming procedures, with a score of 4.6 +/- 0.1. Liberation of fat during insertion of 9-mm nails after reaming was recorded with a score of 3.5 +/- 0.4. In both groups, a positive correlation of fat extravasation with the rise in intramedullary pressure was found (reamed group: r(s) = 0.868; unreamed group: r(s) = 0.698), resulting in significantly less liberation of bone marrow fat in the unreamed stabilized group than in the reamed control group (p < 0.05). The data indicate that fat embolization during nailing procedures after femoral osteotomy increases with increasing intramedullary pressure and occurs in a lesser degree in unreamed than in reamed intramedullary femoral shaft stabilization.

Circulating postinjury neutrophils are primed for the release of proinflammatory cytokines

BACKGROUND

Postinjury neutrophil (PMN) priming identifies the injured patient at risk for the subsequent development of multiple organ failure (MOF). PMN priming has previously been shown to cause enhanced release of proteases and superoxide. PMNs, however, are a rich source of proinflammatory cytokines, such as interleukin (IL)-8 and tumor necrosis factor (TNF), which have been implicated in the development of MOF. PMNs also make IL-1ra, which is an anti-inflammatory cytokine that inhibits IL-1. It is our hypothesis that postinjury PMNs are primed for increased stimulated release of the proinflammatory cytokines IL-8 and TNF but not the anti-inflammatory cytokine IL-1ra.

METHODS

Twelve trauma patients with a mean Injury Severity Score of 24 (+/-4.6) and 10 elective surgical patients were studied. Postinjury PMNs were isolated from blood obtained at presentation (within 2 hours after injury) and 24 hours after trauma. PMNs from elective surgical patients were obtained preoperatively, immediately postoperatively, and at 24 hours. The PMNs were stimulated with platelet-activating factor (200 nM)/N-formyl-methionyl-leucyl-phenylalanine (1 micromol/L) or lipopolysaccharide (100 ng/mL) incubated for 24 hours in RPMI-1640, and release of IL-8, TNF, and IL-1ra were measured.

RESULTS

Postinjury PMNs were primed for both platelet-activating factor/N-formyl-methionyl-leucyl-phenylalanine-stimulated and lipopolysaccharide-stimulated IL-8 and TNF release at 2 hours after injury (fourfold increase of IL-8 release and fivefold increase of TNF release), whereas elective surgical patients demonstrated no priming. In contrast, postinjury patients were not primed for increased release of the counterinflammatory cytokine IL-1ra, suggesting a specific postinjury up-regulation of IL-8 and TNF.

CONCLUSION

After injury, PMNs are primed for proinflammatory cytokine release in addition to superoxide and elastase. This augmented release of IL-8 and TNF may be involved in the subsequent development of organ dysfunction and ultimately MOF.

Predictive value of interleukin 6 (IL-6), interleukin 8 (IL-8) and gastric intramucosal pH (pH-i) in major abdominal surgery

OBJECTIVE

To study plasma concentrations of interleukin 6 (IL-6) and interleukin 8 (IL-8) in patients with splanchnic hypoxia, as documented by gastric intramucosal measurements (pH-i), during major abdominal surgery and the relationship between IL-6 and IL-8 concentrations and postoperative complications as well as clinical outcome.

DESIGN

A prospective study.

PATIENTS

Twelve patients scheduled for major abdominal surgery with no evidence of coexisting infectious disease.

RESULTS

Six out of seven samples from patients with postoperative complications showed intraoperative pH-i levels lower than 7.32 and IL-6 levels higher than 300 pg/ml. Seven out of nine samples from patients without complications showed pH-i levels higher than 7.32 and IL-6 levels lower than 300 pg/ml. The difference in the pattern of distribution was statistically significant (p < 0.01). Only two out of seven samples of patients with postoperative complications showed intraoperative pH-i levels lower than 7.32 and IL-8 levels higher than 60 pg/ml. It was not possible to identify a clear distribution pattern of data points for IL-6 and IL-8 during the postoperative period.

CONCLUSIONS

Intraoperative splanchnic ischemia, as documented by gastric intramucosal pH-i, is directly correlated to the increase of IL-6 plasma levels and to the incidence of postoperative complications, while IL-8 levels showed no correlation with surgical complications.

Regulation of whole blood tumor necrosis factor production upon endotoxin stimulation after severe blunt trauma

BACKGROUND

Trauma has been recognized to be accompanied by alterations of leukocyte functions such as cytokine release. The regulatory principles involved in these changes are still poorly defined. To further characterize leukocyte function after multiple trauma, endotoxin-stimulated tumor necrosis factor (TNF) production of trauma patients' whole blood and a possible regulatory mechanism were studied.

METHODS

Endotoxin responsiveness in trauma patients (n = 18, Injury Severity Score = 24 +/- 7) was assayed ex vivo using a whole blood model. TNF release and TNFalpha mRNA levels were determined during a 14-day period. Furthermore, the influence of patients' sera on whole blood TNF production was evaluated.

MAIN RESULTS

The capacity of trauma patients' whole blood to produce TNF was reduced for 2 to 6 days after trauma and was equally evident for both TNF release and TNFalpha mRNA levels. The reduction of TNF coincides with the appearance of an inhibitory activity for TNF production in trauma patients' sera. No correlation was found between the inhibitory activity and soluble TNF receptors, endotoxin-neutralizing molecules, inhibitory cytokines (interleukin 10 and transforming growth factor beta), or prostaglandins.

CONCLUSIONS

Major trauma leads to the appearance of a circulating inhibitory activity for TNF synthesis that may potentially contribute to an anti-inflammatory response in patients with multiple trauma. The elucidation of its structural and functional properties may contribute to the understanding of the pathogenesis of severely injured patients.

Prolonged hemodynamic stability during arteriovenous carbon dioxide removal for severe respiratory failure

OBJECTIVE

The effects of prolonged arteriovenous carbon dioxide removal on hemodynamics during severe respiratory failure were evaluated in adult sheep with severe smoke inhalation injury.

METHODS

Adult female sheep (n = 6,33.8 +/- 5.2 kg) were subjected to intratracheal cotton severe smoke insufflation to a mean carboxyhemoglobin level of 83% +/- 3%. Twenty-four hours after injury, a low-resistance 2.5 m2 membrane oxygenator was placed in a carotid-to-jugular pumpless arteriovenous shunt at unrestricted flow to allow complete carbon dioxide removal and reductions in ventilator support. Animals remained conscious, and heart rate, cardiac output, mean arterial pressure, and pulmonary arterial pressure were measured at baseline, after injury, and daily during support with the arteriovenous carbon dioxide removal circuit for 7 days.

RESULTS

All animals survived the study period. Carbon dioxide removal ranged from 99.7 +/- 13.7 to 152.2 +/- 16.2 ml/min, and five (83%) of the six animals were successfully weaned from the ventilator before day 7. During full support with the arteriovenous carbon dioxide removal circuit, shunt flow ranged from 1.24 +/- 0.06 to 1.43 +/- 0.08 L/min and accounted for 20.1% +/- 1.4% to 25.9% +/- 2.4% of cardiac output. No statistically significant changes in heart rate, cardiac output, mean arterial pressure, or pulmonary artery pressure were demonstrated over the study course despite the extracorporeal shunt flow.

CONCLUSIONS

Arteriovenous carbon dioxide removal as a simplified means of extracorporeal gas exchange support is relatively safe without adverse hemodynamic effects or complications.

Patterns of cytokine evolution (tumor necrosis factor-alpha and interleukin-6) after septic shock, hemorrhagic shock, and severe trauma

OBJECTIVE

To compare the patterns of evolution of two proinflammatory cytokines (tumor necrosis factor [TNF]-alpha and interleukin-6 [IL-6]) in two major clinical entities associated with systemic inflammatory response: septic shock and multiple trauma (with and without hemorrhagic shock).

DESIGN

Prospective study of two cohorts of patients.

SETTING

Critical care unit and Emergency Center of a university hospital.

PATIENTS

Twenty-five nontrauma patients with septic shock and 60 multiple trauma patients (of whom eight patients were resuscitated from hemorrhagic shock).

INTERVENTIONS

Serial blood samples were collected in each patient for determination of serum cytokine concentrations. Samples were obtained over 7 days in septic shock patients and 11 days in trauma patients. Standard resuscitation techniques were used in each patient. Clinical and laboratory data were prospectively collected.

MEASUREMENTS AND MAIN RESULTS

High concentrations of circulating TNF-alpha and IL-6 were found in patients with septic shock. High IL-6 concentrations, but normal TNF-alpha concentrations were detected in trauma patients. At study entry, TNF-alpha concentrations were higher in nonsurvivor septic shock than in nonsurvivor trauma patients (42 +/- 7 vs 13 +/- 2 pg/mL; p < .001). During the whole study period, nonsurvivor septic shock patients maintained higher TNF-alpha concentrations than nonsurvivor trauma patients (p < .001). In survivors in both groups, normal values for TNF-alpha were detected during the whole study period. At study entry, IL-6 concentrations were significantly higher in nonsurvivor septic shock patients than in nonsurvivor trauma patients (15,627 +/- 4336 vs. 317 +/- 124 pg/mL; p < .0001). During the whole study period, much higher concentrations of IL-6 were detected in septic shock patients than in trauma patients (p < .0001). In survivors, at study entry, IL-6 concentrations were much higher in septic shock patients than in trauma patients (3947 +/- 1410 vs. 247 +/- 41 pg/mL; p < .001). Higher IL-6 concentrations were maintained throughout the study period in septic shock patients than in trauma patients (p < .001). In septic shock patients, changes in both TNF-alpha and IL-6 were correlated with outcome, higher values being found in patients likely to die. Neither TNF-alpha nor IL-6 values were of any significant value in predicting outcome of trauma patients. When septic shock patients were compared with traumatized patients resuscitated from hemorrhagic shock, the former had much higher concentrations of both TNF-alpha and IL-6 throughout the study period (p < .01 to p < .00001). Increased IL-6 values were an indicator of the development of a nosocomial infection in trauma patients. In five trauma patients who developed a nosocomial pneumonia during the study period, the IL-6 concentration was 433 +/- 385 pg/mL before the onset of pneumonia, then peaked at 3970 +/- 1478 pg/mL on day 7, and returned to baseline (219 +/- 58 pg/mL) on day 11.

CONCLUSIONS

In septic shock patients, high amounts of circulating TNF-alpha and IL-6 are found and then correlate with fatal outcome. In trauma patients (even those patients resuscitated from hemorrhagic shock), much less increased concentrations of IL-6 are detected while normal TNF-alpha circulating concentrations are measured. In these patients, cytokine concentrations do not correlate with outcome. This finding suggests a much higher degree of activation of the immunoinflammatory cascade in septic shock than in multiple trauma patients. Increased IL-6 values are an indicator of the development of a nosocomial infection in trauma patients.

Cytokines clearance during venovenous hemofiltration in the trauma patient

The objective of the study was to investigate whether continuous venovenous hemofiltration (CVVH) would facilitate removal of substantial amounts of tumor necrosis factor (TNF) and interleukin-6 (IL-6) from the circulation in traumatized critically ill patients with multiple organ dysfunction syndrome. The study design was a prospective, nonblind, randomized controlled trial that was set in the trauma intensive care unit of a tertiary university referral hospital. Thirty consecutive critically ill, mechanically ventilated trauma patients with multiple organ dysfunction syndrome (without renal failure) were included in the study. Patients were randomized to either CVVH or conventional treatment. Blood and ultrafiltrate samples were collected from each patient before the initiation of CVVH and after 24, 72, and 168 hours of therapy. In the control group, blood samples were collected during the same periods. In the 30 patients studied, 15 had hemofiltration and 15 did not. Both groups were similar with regard to age (36+/-18 years v 36+/-14 years) and severity scores (injury severity score, 32+/-16 v 30+/-11; APACHE II score, 22+/-7 v 21+/-6; Goris score, 5.2+/-1.7 v 5.2+/-1.8). Before CVVH, TNF and IL-6 could be detected in the serum of all patients. The mean concentration of TNF was 17+/-22 pg/mL in patients and 22+/-20 pg/mL in control subjects (P = NS). The mean concentration of IL-6 was 2,153+/-2,824 pg/mL in patients and 1,774+/-1,637 pg/mL in control subjects (P = NS). We found a TNF and IL-6 substantial elimination with CVVH (excretion of TNF [microg/d] at 24, 48, and 168 hours: 112.6+/-161.2, 105.2+/-149.4, and 143.1+/-170.0; excretion of IL-6 [microg/d]: 1,655+/-719, 3,091+/-489, and 2,420+/-366). However, no significant difference was found in serum cytokines concentration between groups during the study: mean serum TNF concentration decreased from the pretreatment level to a mean level of 12+/-9.6 pg/mL in patients and 21+/-27 pg/mL in control subjects. Similar results were found with IL-6 concentration that decreased from the pretreatment level to a mean of 554+/-731 pg/mL in patients and 382 +/-568 pg/mL in control subjects. In conclusion, CVVH is associated with removal of substantial amounts of TNF and IL-6 from the circulation in traumatized critically ill patients, but the profile of these mediators is similar to that of controls, suggesting a nonclinically relevant elimination. Further prospective, randomized, clinical trials are needed to support our results.

Pulmonary effects of fixation of a fracture with a plate compared with intramedullary nailing. A canine model of fat embolism and fracture fixation

Fat-embolism syndrome and pulmonary dysfunction may develop in multiply injured patients who have a fracture of a long bone. Although early fixation of a fracture is beneficial, intramedullary nailing may exacerbate pulmonary dysfunction by causing additional embolization of marrow fat. We examined the pulmonary effects of the timing and method of fixation of a fracture in a canine fat-embolism model. Fat embolism was induced in forty-one adult dogs by reaming the ipsilateral femur and tibia followed by pressurization of the intramedullary canal. The animals were divided into a control group of eight dogs that had induction of fat embolism alone and an experimental group of thirty-three dogs that had induction of fat embolism and internal fixation of a transverse fracture of the middle of the contralateral femoral shaft. In the control group, four dogs each were killed four hours and twenty-four hours after induction of fat embolism. In the experimental group, a femoral fracture was created and fixation was performed four hours after embolic showering in fifteen animals and twenty-four hours after embolization in eighteen animals. The two experimental groups were subdivided according to the method of fixation of the fracture: eleven dogs each had application of a plate, nailing without reaming, and nailing with reaming. The pulmonary arterial pressure and the alveolar-arterial gradient were measured preoperatively, during induction of fat embolism, and as long as one hour after fixation of the fracture but before the animal was killed. The lungs, brain, and kidneys were examined for pathological and physiological evidence of intravascular fat. The intravascular fat persisted for twenty-four hours after induction of pulmonary fat embolism. Pulmonary arterial pressure remained elevated at four hours after the embolic showering, before creation and fixation of the fracture. By twenty-four hours after the induction of fat embolism, pulmonary arterial pressure had returned to the baseline level. Neither the creation nor the fixation of the fracture affected pulmonary arterial pressure. In the animals that had fixation of a fracture four hours after embolization, both nailing with reaming and nailing without reaming produced alveolar-arterial gradients that were higher than the baseline values, whereas fixation with a plate did not change the alveolar-arterial gradient significantly from the baseline value. In addition, the alveolar-arterial gradients in the animals that had nailing with reaming and nailing without reaming four hours after embolization were, respectively, four and 3.5 times higher than that in the animals that had fixation of the femur with a plate. In the animals that had fixation twenty-four hours after embolization, none of the methods for fixation affected the alveolar-arterial gradient. The amount of embolic fat in the lungs, brain, and kidneys was not affected by fixation of the fracture when it was performed at either the four-hour or the twenty-four-hour time-interval. Scores for pulmonary edema were increased by fixation of the fracture, but there was no difference among the scores associated with the three methods of fixation.

CLINICAL RELEVANCE

The findings of the present study indicated that the amount of intravascular fat persisting in the lungs, kidneys, and brain twenty-four hours after pressurization of the intramedullary canal is not affected by the method of fixation of the fracture. Fixation of a fracture is associated with minimum evidence of acute inflammation and has no effect on pulmonary artery pressure. The development of pulmonary dysfunction from fat emboli depends on other factors, not just on the presence of fat in pulmonary vessels. It appears that the method of fracture fixation has little influence on the outcome of treatment.

Prediction of posttraumatic adult respiratory distress syndrome by albumin excretion rate eight hours after admission

BACKGROUND

Adult respiratory distress syndrome (ARDS) in trauma victims carries a mortality on the order of 50%. An early feature is an increased capillary permeability causing an extravasation of plasma proteins and water, leading to interstitial edema. In the kidney, the increase in microvascular permeability is manifested as increased albumin excretion detectable by sensitive immunoassay.

METHODS

Forty seven trauma victims were studied for 5 days; 32 of them had Injury Severity Scores > 18. A diagnosis of ARDS was made on the recommendations of the American-European Consensus Conference on ARDS (1994). Eight patients developed ARDS, five developed pulmonary dysfunction, and the remainder showed no significant pulmonary abnormality.

RESULTS

Using the near patient urine albumin immunoassay, albumin excretion rate (AER) was measured after admission. For patients with Injury Severity Score > 18, the median (95% confidence interval) AER 8 hours after admission was 63 (range, 40-99) microg per minute for those without impaired lung function and 339 (range, 162-454) microg per minute for those in the combined ARDS and pulmonary dysfunction group (Mann-Whitney test, p = 0.0004). The median AER was 51 (range, 27-98) microg per minute for patients with Injury Severity Score < 18. The positive predictive value for the development of ARDS or pulmonary dysfunction of AER > 130 microg per minute was 85%, with a negative predictive value of 95%.

CONCLUSIONS

These data indicate that the capillary leak associated with the subsequent development of pulmonary dysfunction and ARDS can be detected within 8 hours of admission at the patient's bedside, thus providing a means of early identification of patients at greatest risk and allowing for early intervention.

Intramedullary pressure and bone marrow fat intravasation in unreamed femoral nailing

OBJECTIVE

To investigate whether intramedullary pressure and bone marrow fat embolization are different in unreamed compared with conventional reamed femoral nailing. The null hypothesis is that there is no difference between the two techniques.

DESIGN

A prospective consecutive nonrandomized clinical trial.

METHODS

Intramedullary pressure was measured in the distal femoral fracture fragment at the supracondylar region. Bone marrow fat intravasation was measured by means of the modified Gurd-test. Monitoring was carried out in 31 unreamed and eight reamed intramedullary femoral nailing procedures.

RESULTS

Intramedullary pressure increased in the unreamed group to 82 +/- 11 mm Hg during the insertion of 9-mm and 10-mm nails and in the reamed group to 396 +/- 85 mm Hg during reaming of the medullary cavity. Insertion of nails after reaming led to an increase in intramedullary pressure of 79 +/- 13 mm Hg. A positive correlation between fat intravasation and intramedullary pressure was found in each group (rs = 0.73), resulting in less liberation of bone marrow fat in the unreamed group than in the reamed group.

CONCLUSIONS

Intramedullary pressure increased significantly in the reamed more than in the unreamed group. Bone marrow fat intravasation depended on the rise in intramedullary pressure, and occurred less frequently in unreamed than in reamed intramedullary femoral fracture stabilization.

Rupture of an abdominal aortic aneurysm causes priming of phagocytic oxidative burst

PURPOSE

The purpose of this investigation was to determine whether rupture and repair of an abdominal aortic aneurysm induced activation of phagocyte oxidant burst, reflecting a systemic inflammatory state, when compared with elective abdominal aortic aneurysm (AAA) repair.

METHODS

Blood samples were harvested from 22 patients with elective AAA and 15 patients with ruptured AAA. Phagocyte oxidant activity was measured in response to a panel of activators with luminol and lucigenin as chemiluminescent substrates. Activity of the complement pathways was measured with plasma levels of C3a des arg.

RESULTS

Elective AAA repair resulted in significant elevation in phagocyte count and oxidative activity after surgery in response to maximal dose phorbol myristate acetate (PMA) when compared with the baseline sample. In patients with ruptured AAA the oxidative activity of phagocytes was significantly increased in response to both unopsonized zymosan (899.8 +/- 192 ruptured vs 300 +/- 40 elective, p < 0.01) and maximal dose PMA (8769 +/- 2011 vs 3508 +/- 382, p < 0.01) compared with elective cases at the initial sampling. Phagocyte priming has occurred by way of two distinct pathways: receptor-mediated (unopsonized zymosan, CR3 receptor) and receptor-independent (PMA, protein kinase c).

CONCLUSIONS

Rupture of an AAA resulted in priming of the phagocyte oxidant capacity before operative repair compared with elective AAA. Phagocyte activation is a critical component of the systemic inflammatory response that may contribute to the high incidence of systemic organ dysfunction and death in this patient group.