Bilateral lavage with diluted surfactant improves lung function after unilateral lung contusion in pigs*

Exogenous surfactant for lung contusion causing ARDS: A systematic review of clinical and experimental reports

This systematic review aimed to summarize the available data on the treatment of pulmonary contusions with exogenous surfactants, determine whether this treatment benefits patients with severe pulmonary contusions, and evaluate the optimal type of surfactant, method of administration, and drug concentration. Three databases (MEDline, Scopus, and Web of Science) were searched using the following keywords: pulmonary surfactant, surface-active agents, exogenous surfactant, pulmonary contusion, and lung contusion for articles published between 1945 and February 2023, with no language restrictions. Four reviewers independently rated the studies for inclusion, and the other four reviewers resolved conflicts. Of the 100 articles screened, six articles were included in the review. Owing to the limited number of papers on this topic, various types of studies were included (two clinical studies, two experiments, and two case reports). In all the studies, surfactant administration improved the selected ventilation parameters. The most frequently used type of surfactant was Curosurf® in the concentration of 25 mg/kg of ideal body weight. In most studies, the administration of a surfactant by bronchoscopy into the segmental bronchi was the preferable way of administration. In both clinical studies, patients who received surfactants required shorter ventilation times. The administration of exogenous surfactants improved ventilatory parameters and, thus, reduced the need for less aggressive artificial lung ventilation and ventilation days. The animal-derived surfactant Curosurf® seems to be the most suitable substance; however, the ideal concentration remains unclear. The ideal route of administration involves a bronchoscope in the segmental bronchi.

Veno-venous ECMO as a platform to evaluate lung lavage and surfactant replacement therapy in an animal model of severe ARDS

BACKGROUND

There are limited therapeutic options directed at the underlying pathological processes in acute respiratory distress syndrome (ARDS). Experimental therapeutic strategies have targeted the protective systems that become deranged in ARDS such as surfactant. Although results of surfactant replacement therapy (SRT) in ARDS have been mixed, questions remain incompletely answered regarding timing and dosing strategies of surfactant. Furthermore, there are only few truly clinically relevant ARDS models in the literature. The primary aim of our study was to create a clinically relevant, reproducible model of severe ARDS requiring extracorporeal membrane oxygenation (ECMO). Secondly, we sought to use this model as a platform to evaluate a bronchoscopic intervention that involved saline lavage and SRT.

METHODS

Yorkshire pigs were tracheostomized and cannulated for veno-venous ECMO support, then subsequently given lung injury using gastric juice via bronchoscopy. Animals were randomized post-injury to either receive bronchoscopic saline lavage combined with SRT and recruitment maneuvers (treatment, n = 5) or recruitment maneuvers alone (control, n = 5) during ECMO.

RESULTS

PaO₂/FiO₂ after aspiration injury was 62.6 ± 8 mmHg and 60.9 ± 9.6 mmHg in the control and treatment group, respectively (p = 0.95) satisfying criteria for severe ARDS. ECMO reversed the severe hypoxemia. After treatment with saline lavage and SRT during ECMO, lung physiologic and hemodynamic parameters were not significantly different between treatment and controls.

CONCLUSIONS

A clinically relevant severe ARDS pig model requiring ECMO was established. Bronchoscopic saline lavage and SRT during ECMO did not provide a significant physiologic benefit compared to controls.

The Effects of Dexmedetomidine and Ketamine on Oxidative Injuries and Histological Changes Following Blunt Chest Trauma

BACKGROUND

The objective of this research was to evaluate the oxidative and histopathological effects of dexmedetomidine and ketamine on the pulmonary contusion model resulting from blunt chest trauma.

METHODS

Rats were randomly assigned to 5 equal groups (n=6): control group (Group C), pulmonary contusion group (Group PC), PC-dexmedetomidine group (Group PC-D), PC-ketamine group (Group PC-K), and PC-dexmedetomidine + ketamine (Group PC-D+K). The PC was performed by dropping a weight of 500 g (2.45 Joules) from a height of 50 cm. In Group PC-D, after chest trauma, dexmedetomidine (100 µg/kg) was administered intraperitoneally. In Group PC-K, after chest trauma, ketamine (100 mg/kg) was administered intraperitoneally. In Group PC-D+K, dexmedetomidine and ketamine were administered together. At the end of the 6th hour, rats were sacrificed. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activities, neutrophil infiltration/aggregation, and thickness of the alveolar wall were evaluated.

RESULTS

MDA levels were significantly higher in Group PC than Groups C, PC-D, and PC-D+K. SOD enzyme activity was significantly higher in Group PC than Groups C, PC-D, and PC-D+K. In addition, neutrophil infiltration/aggregation and total pulmonary injury scores were significantly higher in Group PC than in other groups, and the thickness of the alveolar wall was significantly higher in Group PC compared to Groups C, PC-D, and PC-D+K. MDA level, SOD enzyme activities, neutrophil infiltration/aggregation, and thickness of alveolar wall were similar in PC-D and PC-D+K groups.

CONCLUSION

Dexmedetomidine and dexmedetomidine+ketamine have protective effects on blunt chest trauma but no protective effect was observed when ketamine was administered alone. We concluded that the administration of dexmedetomidine and ketamine after contusion is beneficial against pulmonary injury in rats.

Investigation of histopathological and radiological effects of surfactant treatment in an experimental female rat model of lung contusion

Objective(s):

Pulmonary contusion (PC) is a clinical entity that often accompanies blunt traumas. We aimed to investigate the radiological and histopathological effects of surfactant treatment in an experimental rat model in which lung contusion was formed by blunt thoracic trauma.

Materials and Methods:

50 female Sprague-Dawley rats were used. Five groups were formed randomly. In groups 2, 4, and 5 lung contusion was made by the drop-weight method after anesthesia. Intratracheal surfactant was administered in the 4th hr in groups 3 and 4 and in the 24th hr in groups 4 and 5. All rats were sacrificed and their lungs removed at 48 hr after contusion. Alveolar edema, congestion, hemorrhage, destruction, leukocyte infiltration, immune staining were examined histopathologically.

Results:

When the first thoracic CT scans were evaluated, we observed two rats with rib fractures and four rats with pneumothorax. 4 and 48 hr thoracic CT evaluation contusion and atelectasis showed no statistically significant decrease (P>0.05). After sacrifice of group 2, in macroscopic evaluation, there was a heterogeneous contusion and hemorrhagic appearance in the lungs of rats and less hemorrhagic appearance was observed in Groups 4 and 5 than in Group 2. In comparison of Immunohistopathological findings, surfactant treatment showed a statistically significant decrease in leukocyte infiltration scores (P=0.046). Immunohistopathologically, surfactant group had more staining but only statistically significant when compared to groups 4 and sham. (P=0.036).

Conclusion:

Surfactant treatment may be of significant benefit in lung contusion secondary to blunt chest trauma, and further prospective evidence of its efficacy in such disorders is needed.

Effect of nitric oxide synthase inhibitors in acute lung injury due to blunt lung trauma in rats

Background

This study aims to investigate the effects of blunt lung trauma performed in experimental rat model on lung tissue and blood as well as proinflammatory cytokines, oxidant-antioxidant enzymes and histopathological parameters after Ngamma-nitro-L-arginine methyl ester and N-iminoethyl-L-ornithine administration.

Methods

The study included 50 adult male Wistar albino rats (weighing 350 to 400 g). Rats were randomly allocated into four groups. Except in the control, moderate-level pulmonary contusion was created in all other groups. Intraperitoneal saline solution was performed in groups 1 and 2, 25 mg.kg-1 Ngamma-nitro-L-arginine methyl ester in group 3, and 20 mg.kg-1 N-iminoethyl-L-ornithine in group 4. Blood and lung tissues were studied biochemically and histopathologically.

Results

Best outcomes were recorded statistically significantly in groups with administration of Ngamma-nitro-L-arginine methyl ester and N-iminoethyl-L-ornithine when malondialdehyde response, mucous and histopathological values were examined. Significant improvement was detected in superoxide dismutase values in the group with administration of competitive nitric oxide synthase inhibitor Ngamma-nitro-L-arginine methyl ester. Nitric oxide values were substantially decreased in N-iminoethyl-L-ornithine group, while no significance was detected.

Conclusion

Free oxygen radicals and lipid peroxidation played a role in pulmonary contusion after blunt lung trauma. According to biochemical and histopathological outcomes, effects of inflammation were decreased and protective effects were formed with administration of both Ngammanitro- L-arginine methyl ester and N-iminoethyl-L-ornithine.

Effect of vitamin C and vitamin E on lung contusion: A randomized clinical trial study

There is association between lung contusion (lC) and a progressive inflammatory response. The protective effect of vitamin C and vitamin E, as strong free radical scavengers on favourite outcome of (LC) in animal models, has been confirmed.

Design

to evaluate the effect of vitamins, E and C on arterial blood gas (ABG) and ICU stay, in (LC), with injury severity score (ISS) 18 ± 2, due to blunt chest trauma.

Methods

This study was a randomized, double-blind, placebo-controlled clinical trial. Patients with (ISS) 18 ± 2 blunt chest trauma, who meet criteria, participated in the study. A total of 80 patients from Feb 2015 to Jun2018and were randomly divided into 4 groups. Patients received intravenous vitamin E (1000IU mg), was (group I); intravenous vitamin C (500) (group II). Vitamin C + vitamin E = (group III), and intravenous distilled water = (control group) or (group IV). ABG, serum cortisol, and CRP levels were determined at baseline, 24 h and 48 h after the intervention.

Results

a significant decrease in ICU stay in group III compared to other groups (p < 0.001). Co-administration of vitamin C and vitamin E showed significant increases pH (values to reference range from acidemia”), oxygen pressure, and oxygen saturation in group III compared to other groups (p < 0.001). A significant decrease in carbon dioxide pressure was also detected after receiving vitamin C and vitamin E in group III, compared to other groups (p < 0.001). There was no significant difference cortisol and CRP levels between groups after the intervention.

Conclusion

Co-administration of vitamin C and vitamin E, improve the ABG parameters and reduce ICU stay.

•

Most previous studies about pulmonary contusion were performed on animal model, this is a human study in surgery ICU.

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Administration of vitamin C and vitamin E showed protective effects on pulmonary contusion, co-administration of them also was more effective.

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PH values, oxygen pressure, and oxygen saturation was significantly increase in group III compared to other groups (p < 0.001). carbon dioxide pressure also was significantly decrease in group III.

•

Mean ICU stay in group III (co-administration of vit C + E compare with control group, significantly decreased, p < 0.001).

Surfactants in Acute Respiratory Distress Syndrome in Infants and Children: Past, Present and Future

There is a lack of definitive data on the effective management of acute respiratory distress syndrome (ARDS) in infants and children. The development and validation of the Berlin definition (BD) for ARDS and the Pediatric Acute Lung Injury Consensus Conference (PALICC) recommendations in children represented a major advance in optimizing research and treatment, mainly due to the introduction of a severe ARDS category. Proposed reasons for the lack of consistent results with surfactants in children and infants compared with neonates include different causes, type of lung damage (direct or indirect), timing and mode of administration as well as the type of surfactant used. Secretory phospholipase A2 plays an important role in inflammation and possible dysfunction of surfactants in ARDS. Bronchoalveolar lavage (BAL) with normal saline and surfactant allows the removal of inhaled material, the recruitment of non-ventilating areas and the maintenance of the surfactant pool size. BAL with diluted surfactant allows rapid absorption of the surfactant at the air/liquid interface, which blocks the progression of pathological lung disease and in turn disrupts the inflammatory cycle. Importantly, it is now recognized that the type of surfactant, the time of administration and the method of administration could all play an important role in the management of ARDS, and there is evidence that surfactant is effective and well tolerated in children and infants with ARDS.

Protective effects of rosuvastatin in a rat model of lung contusion: Stimulation of the cyclooxygenase 2-prostaglandin E-2 pathway

BACKGROUND

Lung contusion, which can occur in patients with blunt thoracic trauma, is a leading risk factor for development of acute lung injury (ALI) and acute respiratory distress syndrome. Statins are lipid-lowering drugs with many beneficial antiinflammatory and antioxidative effects. We therefore hypothesized that the administration of statins immediately after trauma will inhibit the production of inflammatory mediators, and thereby alleviate the severity of lung injury.

METHODS

A model of blunt chest injury in rat was employed. The effects of statins (rosuvastatin) and cyclooxygenase-2 (COX-2) inhibitors (meloxicam) on ALI were assessed by measuring inflammatory mediator levels in the serum and in the bronchoalveolar space. Animals were killed at the end of day 3. Histologic evaluation of lung tissue was performed to confirm the presence and severity of lung contusion as well as the effects of statins, nonsteroidal antiinflammatory drugs, and their combination.

RESULTS

Administration of meloxicam after lung contusion decreased the amount of neutrophil infiltration; however, marked hemorrhage and edema were still noticed. Administration of rosuvastatin decreased significantly cytokine levels that were increased after the blunt chest trauma. Rosuvastatin increased the expression of inducible nitric oxide (iNOS), COX-2, heme oxygenase-1 (HO-1), and prostaglandin E2 (PGE-2) in the bronchoalveolar lavage fluid of the rat contused lungs. Coadministration of meloxicam prevented these changes.

CONCLUSION

Rosuvastatin treatment after lung contusion attenuated several features of ALI. The enhanced activity of iNOS, COX-2, and HO-1 in the lung may reflect the advent of protective processes that took place in the contused lung. To our knowledge, this is the first demonstration that prostaglandin pathways play an essential role in the effects of statins in lung injury.

Combined hemorrhage/trauma models in pigs-current state and future perspectives

The majority of injury combinations in multiply injured patients entail the chest, abdomen, and extremities. Numerous pig models focus on the investigation of posttraumatic pathophysiology, organ performance monitoring and on potential treatment options. Depending on the experimental question, previous authors have included isolated insults (controlled or uncontrolled hemorrhage, chest trauma) or a combination of these injuries (hemorrhage with abdominal trauma, chest trauma, traumatic brain injury, and/or long-bone fractures). Combined trauma models in pigs can provide a high level of clinical relevance, when they are properly designed and mimicking the clinical situation. Most of these models focus on the first hours after trauma, to assess the acute sequel of traumatic hemorrhage. However, hemorrhagic shock and the associated mass transfusion are also major causes for organ failure and mortality in the later clinical course. Thus, most models lack information on the pathomechanisms during the late posttraumatic phase. Studying new therapies only during the early phase is also not reflective of the clinical situation. Therefore, a longer observation period is required to study the effects of therapeutic approaches during intensive care treatment when using animal models. These long-term studies of combined trauma models will allow the development of valuable therapeutic approaches relevant for the later posttraumatic course. This review summarizes the existing porcine models and outlines the need for long-term models to provide real effective novel therapeutics for multiply injured patients to improve organ function and clinical outcome.

N-Acetylcysteine counteracts oxidative stress and protects alveolar epithelial cells from lung contusion-induced apoptosis in rats with blunt chest trauma

The aim of this study was to investigate the protective effects of N-acetylcysteine (NAC) on peroxidative and apoptotic changes in the contused lungs of rats following blunt chest trauma. The rats were randomly divided into three groups: control, contusion, and contusion + NAC. All the rats, apart from those in the control group, performed moderate lung contusion. A daily intramuscular NAC injection (150 mg/kg) was given immediately following the blunt chest trauma and was continued for two additional days following cessation of the trauma. Samples of lung tissue were taken in order to evaluate the tissue malondialdehyde (MDA) level, histopathology, and epithelial cell apoptosis using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and active caspase-3 immunostaining. In addition, we immunohistochemically evaluated the expression of surfactant protein D (SP-D) in the lung tissue. The blunt chest trauma-induced lung contusion resulted in severe histopathological injury, as well as an increase in the MDA level and in the number of cells identified on TUNEL assay together with active caspase-3 positive epithelial cells, but a decrease in the number of SP-D positive alveolar type 2 (AT-2) cells. NAC treatment effectively attenuated histopathologic, peroxidative, and apoptotic changes, as well as reducing alterations in SP-D expression in the lung tissue. These findings indicate that the beneficial effects of NAC administrated following blunt chest trauma is related to the regulation of oxidative stress and apoptosis.

Antioxidant vitamins C, E and coenzyme Q10 vs dexamethasone: comparisons of their effects in pulmonary contusion model

Background

The goal of our study is to evaluate the effects of antioxidant vitamins (vitamin C and E), Coenzyme Q10 (CoQ10) and dexamethasone (Dxm) in experimental rat models with pulmonary contusion (PC).

Methods

Rats were randomly divided into six groups. Except for the control, all subgroups had a moderate pulmonary contusion. Animals in the group I and group II received intraperitoneal saline, group III received 10mg.kg-1 CoQ10 group IV received 100mg.kg-1 vitamin C, group V received 150mg.kg-1 vitamin E, and group VI received 10mg.kg-1 Dxm. Blood gas analysis, serum nitric oxide (NO) and malondialdehyde (MDA) levels as well as superoxide dismutase (SOD) activity assays, bronchoalveolar lavage (BAL) fluid and histopathological examination were performed.

Results

Administration of CoQ10 resulted in a significant increase in PaO2 values compared with the group I (p = 0.004). Levels of plasma MDA in group II were significantly higher than those in the group I (p = 0.01). Early administration of vitamin C, CoQ10, and Dxm significantly decreased the levels of MDA (p = 0.01). Lung contusion due to blunt trauma significantly decreased SOD activities in rat lung tissue compared with group I (p = 0.01). SOD levels were significantly elevated in animals treated with CoQ10, Vitamin E, or Dxm compared with group II (p = 0.01).

Conclusions

In our study, CoQ10, vitamin C, vitamin E and Dxm had a protective effect on the biochemical and histopathological outcome of PC after experimental blunt thorax trauma.

Computed tomography assessment of exogenous surfactant-induced lung reaeration in patients with acute lung injury

Introduction

Previous randomized trials failed to demonstrate a decrease in mortality of patients with acute lung injury treated by exogenous surfactant. The aim of this prospective randomized study was to evaluate the effects of exogenous porcine-derived surfactant on pulmonary reaeration and lung tissue in patients with acute lung injury and acute respiratory distress syndrome (ALI/ARDS).

Methods

Twenty patients with ALI/ARDS were studied (10 treated by surfactant and 10 controls) in whom a spiral thoracic computed tomography scan was acquired before (baseline), 39 hours and 7 days after the first surfactant administration. In the surfactant group, 3 doses of porcine-derived lung surfactant (200 mg/kg/dose) were instilled in both lungs at 0, 12 and 36 hours. Each instillation was followed by recruitment maneuvers. Gas and tissue volumes were measured separately in poorly/nonaerated and normally aerated lung areas before and seven days after the first surfactant administration. Surfactant-induced lung reaeration was defined as an increase in gas volume in poorly/non-aerated lung areas between day seven and baseline compared to the control group.

Results

At day seven, surfactant induced a significant increase in volume of gas in poorly/non-aerated lung areas (320 ± 125 ml versus 135 ± 161 ml in controls, P = 0.01) and a significant increase in volume of tissue in normally aerated lung areas (189 ± 179 ml versus -15 ± 105 ml in controls, P < 0.01). PaO₂/FiO₂ ratio was not different between the surfactant treated group and control group after surfactant replacement.

Conclusions

Intratracheal surfactant replacement induces a significant and prolonged lung reaeration. It also induces a significant increase in lung tissue in normally aerated lung areas, whose mechanisms remain to be elucidated.

Trial registration

NCT00742482.

Selective medicated (saline + natural surfactant) bronchoalveolar lavage in unilateral lung contusion. A clinical randomized controlled trial

OBJECTIVE

Open lung and low tidal volume ventilation appear to be a promising ventilation for chest trauma as it can reduce ARDS and improve outcome. Local therapy (e.g. BAL) can be synergic to remove from the lung the debris, mitigate inflammatory cascade and avoid damage spreading to not compromised lung areas.

MATERIALS AND METHODS

44 pulmonary contused patients were randomized to receive broncho-suction and volume controlled low tidal volume ventilation-VCLTVV (Control Group) or the same ventilation plus medicated (saline + surfactant) BAL (Treatment Group). Tidal volume <10 ml/kg, PEEP of 10-12 cm H(2)O and PaO(2) 60-100 mm Hg and PaCO(2) 35-45 mm Hg were used in both groups. BAL was performed using a fiberscope. 4 boluses of 25 ml saline with 2.4 mg/ml of surfactant were introduced into each contused lobe in which, subsequently, 240 mg of surfactant was instilled.

RESULTS

All patients survived. In the Control Group 18 patients developed pneumonia, 5 ARDS and days of intubation were 11.50 (3.83) compared to 5.05 (1.21) of Treatment Group in which OI and PaO(2)/FiO(2) significantly improved from 36 h.

CONCLUSIONS

VCLTVV alone was not able to prevent ARDS and infection in the Control Group as the reduction of intubation. In the Treatment Group, VCLTVV and medicated BAL facilitated the removal of degradated lung material and recruited the contused lung regions, enabling the healing of the lung pathology.

Lung contusion: inflammatory mechanisms and interaction with other injuries

This article reviews current animal models and laboratory studies investigating the pathophysiology of lung contusion (LC), a common and severe condition in patients with blunt thoracic trauma. Emphasis is on studies elucidating cells, mediators, receptors, and processes important in the innate pulmonary inflammatory response that contribute to LC injury. Surfactant dysfunction in the pathogenesis of LC is also discussed, as is the potential role of epithelial cell or neutrophil apoptosis. Studies examining combination injuries where LC is exacerbated by secondary insults such as gastric aspiration in trauma patients are also noted. The need for continuing mechanism-based research to further clarify the pathophysiology of LC injury, and to define and test potential therapeutic interventions targeting specific aspects of inflammation or surfactant dysfunction to improve clinical outcomes in patients with LC, is also emphasized.

Effects of early administration of dexamethasone, N-acetylcysteine and aprotinin on inflammatory and oxidant-antioxidant status after lung contusion in rats

INTRODUCTION

This experimental setting was undertaken to elucidate and confirm the role of inflammatory and oxidant-antioxidant mechanisms on blunt injury induced moderate pulmonary contusion (PC). We intended to determine the effects of dexamethasone (DXM), N-acetylcysteine (NAC) and aprotinin (APR) in terms of their ability to diminish the consequences of acute lung injury due to PC.

METHODS

Rats were allocated to five subgroups. Except for the control, all subgroups had a moderate pulmonary contusion. Following 45 min of observation, animals in groups I and II received intraperitoneal saline, group III 10 mg/kg DXM, group IV 500 mg/kg NAC and group V 30,000 kIU/ml APR. After the procedure, 6 h after contusion, blood gas analysis, lung tissue nitric oxide (NO) and malondialdehyde (MDA) levels, superoxide dismutase (SOD) and catalase (CAT) activity, bronchoalveolar lavage (BAL) fluid and histopathological examination were performed.

RESULTS

All PaO(2) values decreased significantly in contused rats as compared with the control group (p<0.05). DXM, NAC and APR resulted in a slight increase in PaO(2) values compared with group II (p<0.05). Lung tissue levels of MDA and NO were higher in the contusion group than in the control (p<0.05). DXM, NAC and APR all decreased the levels of MDA and NO (p<0.05), however the decrease in NO was not found to be significant with APR (p>0.05). SOD and CAT activities increased significantly after contusion compared to control group (p<0.05). There was no significant difference even though SOD levels were elevated in groups III, IV and V compared with contused animals (p>0.05). Neutrophils in BAL fluid significantly increased in contused animals (p<0.05). Only DXM significantly decreased neutrophil population in BAL fluid (p<0.05). Scores for alveolar haemorrhage/oedema were higher in all contusion-performed rats than those in the control (p<0.05). Compared with the other drugs, only APR significantly improved the haemorrhage/oedema scores compared to sham animals (p=0.024).

CONCLUSIONS

Our findings demonstrate that moderate bilateral PC induced by blunt chest trauma leads to an early inflammatory process which is clearly associated with activation of the oxidant-antioxidant cascade. On this basis, early supportive treatment with DXM, NAC and APR may yield favourable results on pulmonary pathophysiological parameters which are adversely affected due to PC.

Surfactant dysfunction in lung contusion with and without superimposed gastric aspiration in a rat model

This study investigates surfactant dysfunction in rats with lung contusion (LC) induced by blunt chest trauma. Rats at 24 h postcontusion had a decreased percent content of large surfactant aggregates in cell-free bronchoalveolar lavage (BAL) and altered large-aggregate composition with decreased phosphatidylcholine (PC), increased lyso-PC, and increased protein compared with uninjured controls. The surface activity of large aggregates on a pulsating bubble surfactometer was also severely impaired at 24 h postcontusion. Decreases in large surfactant aggregate content and surface activity were improved, but still apparent, at 48 and 72 h postcontusion compared with uninjured control rats and returned to normal by 96 h postcontusion. The functional importance of surfactant abnormalities in LC injury was documented in pilot studies showing that exogenous surfactant replacement at 24 h postcontusion improved inflation/deflation lung volumes. Additional experiments investigated a clinically relevant combination of LC plus gastric aspiration (combined acid and small gastric food particles) and found reductions in large surfactant aggregates in BAL similar to those for LC. However, rats given LC + combined acid and small gastric food particles versus LC had more severe surfactant dysfunction based on decreases in surface activity and alterations in large aggregate composition. Combined data for all animal groups had strong statistical correlations between surfactant dysfunction (increased minimum surface tension, decreased large aggregates in BAL, decreased aggregate PC, and increased aggregate lyso-PC) and the severity of inflammatory lung injury (increased total protein, albumin, protein/phospholipid ratio, neutrophils, and erythrocytes in BAL plus increased whole lung myeloperoxidase activity). These results show that surfactant dysfunction is important in the pathophysiology of LC with or without concurrent gastric aspiration and provides a rationale for surfactant replacement therapy in these prevalent clinical conditions.

[Value of surfactant replacement therapy in the treatment of acute respiratory distress syndrome]

Acute respiratory distress syndrome (ARDS) is a common, devastating clinical problem arising from a number of conditions, such as pneumonia, trauma or sepsis. Because of its significant mortality and morbidity, ARDS has been in the focus of extensive experimental and clinical research. Since there is little doubt that alterations of the surfactant system contribute to lung dysfunction and the onset of ARDS, several clinical studies examined the therapeutic safety and efficacy of a surfactant replacement therapy. Clinical experience with exogenous surfactant has proven inconsistent as a therapeutic modality for adult patients with ARDS. This is mainly due to a number of confounding factors, e.g. severity of injury at the time of treatment, dosing regimes and delivery methods used in different trials. However, current data suggest that patients with direct ARDS (e.g. pneumonia, aspiration) could benefit from surfactant replacement therapy rather than patients with indirect ARDS (e.g. sepsis, trauma). Although surfactant replacement therapy has been shown to significantly reduce mortality in neonates with ARDS, there has been no large randomised clinical trial showing that exogenous surfactant improves outcome in adults with respiratory failure. Therefore, surfactant therapy cannot be recommended for routine clinical use in adult patients and has to be considered as a last resort treatment.

Epithelial cell apoptosis and neutrophil recruitment in acute lung injury-a unifying hypothesis? What we have learned from small interfering RNAs

In spite of protective ventilatory strategies, Acute Lung Injury (ALI) remains associated with high morbidity and mortality. One reason for the lack of therapeutic options might be that ALI is a co-morbid event associated with a diverse family of diseases and, thus, may be the result of distinct pathological processes. Among them, activated neutrophil- (PMN-) induced tissue injury and epithelial cell apoptosis mediated lung damage represent two potentially important candidate pathomechanisms that have been put forward. Several approaches have been undertaken to test these hypotheses, with substantial success in the treatment of experimental forms of ALI. With this in mind, we will summarize these two current hypotheses of ALI briefly, emphasizing the role of apoptosis in regulating PMN and/or lung epithelial cell responses. In addition, the contribution that Fas-mediated inflammation may play as a potential biological link between lung cell apoptosis and PMN recruitment will be considered, as well as the in vivo application of small interfering RNA (siRNA) as a novel approach to the inhibition of ALI and its therapeutic implications.

Flail chest and pulmonary contusion

Flail chest is most often accompanied by a significant underlying pulmonary parenchymal injury and can be a life-threatening thoracic injury. Its management is often complicated by the other injuries it is frequently associated with. Similarly, mortality and morbidity are dictated most often by the associated injuries and findings. Its treatment is complex and should first be one of pain management, judicious fluid resuscitation, and excellent pulmonary toilet. In those patients requiring mechanical ventilatory support, or who require ipsilateral thoracocotomy, rib stabilization may be considered depending on a host of potentially conflicting indications and contraindications. At the end of this section are listed the current major recommendations and their levels of evidence.

The effect of exogenous surfactant in patients with lung contusions and acute lung injury

OBJECTIVE

To investigate the acute effect of surfactant replacement in multiple-trauma patients with lung contusion and acute lung injury.

DESIGN AND SETTING

Prospective randomized clinical trial in the 14-bed ICU of a 750-bed university hospital.

PATIENTS AND PARTICIPANTS

Sixteen ventilated trauma patients with severe refractory hypoxemia (PaO(2)/FIO(2)<150 mmHg) and lung contusions.

INTERVENTIONS

Patients were randomly assigned to either surfactant administration (n=8) or standard treatment (n=8). A single dose of natural bovine surfactant was instilled bronchoscopically in the involved lung areas; each segmental bronchus received (200/19) mg/kg body weight.

MEASUREMENTS AND RESULTS

The surfactant group demonstrated an acute improvement in oxygenation after surfactant replacement compared both to control group and to baseline values. In the surfactant group PaO(2)/FIO(2) increased from 100+/-20 mmHg at baseline to 140+/-20 (6 h), 163+/-26 (12 h), and 187+/-30 mmHg (24h). Compliance increased from 30 to 36 ml/cmH(2)O at 6 h after administration, and this increase remained significant at the 24, 48, and 72 h time points. The surfactant group demonstrated a higher response to recruitment maneuvers than the control group at 6 h. The mean duration of ventilatory support was 5.6 +/-2.6 days in the surfactant group and 8.1+/-2.4 days in the control group.

CONCLUSIONS

Surfactant replacement was well tolerated in patients with lung contusions and severe hypoxemia and resulted in improved oxygenation and compliance.

The pulmonary and hepatic immune microenvironment and its contribution to the early systemic inflammation following blunt chest trauma

OBJECTIVE

Blunt chest trauma is accompanied by an early increase in plasma cytokine concentrations. However, the local sources of these mediators are poorly defined. We investigated the impact of blunt chest trauma on the inflammatory mediator milieu in different compartments (lung tissue, bronchoalveolar lavage, liver tissue, Kupffer cells, plasma) along with the time course of trauma-induced pulmonary endothelial barrier dysfunction to elucidate potential relationships. In addition, the correlation between intratracheally instilled interleukin-6 and its systemic release were studied.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

Basic science laboratory of a university affiliated level 1 trauma center.

SUBJECTS

Male C3H/HeN mice, 8-9 wks old, n = 141.

INTERVENTIONS

Blunt chest trauma induced by a focused blast wave, intravenous injection of Evans blue, and intratracheal instillation of recombinant human interleukin-6.

MEASUREMENTS AND MAIN RESULTS

Two hours after blunt chest trauma, plasma interleukin-6 was markedly increased. Simultaneously, interleukin-6, tumor necrosis factor-alpha, macrophage inflammatory protein-2, monocyte chemotactic polypeptide-1 and neutrophil/monocyte accumulation in bronchoalveolar lavage and interleukin-6, monocyte chemotactic polypeptide-1, and myeloperoxidase activity in lung tissue were significantly increased. This was accompanied by a coinciding elevation in the Evans blue lung-plasma ratio. Recombinant human interleukin-6, instilled intratracheally before blunt chest trauma, was detected in a dose-dependent manner in the plasma of the mice. Additionally, Kupffer cell interleukin-6, tumor necrosis factor-alpha, and interleukin-10 production was significantly augmented as early as 30 mins after the insult.

CONCLUSIONS

These results indicate that early increased cytokine concentrations in the lung, particularly interleukin-6, are important mediator sources as their local peak coincides with the systemic inflammatory response and is accompanied by a simultaneous impaired function of the pulmonary endothelial barrier. A direct relationship between their local and systemic concentrations can be established. Furthermore, this is the first study to show that Kupffer cells are activated early after blunt chest trauma.