Diagnosis and treatment of smoke inhalation

Nebulized Heparin for Adult Patients With Smoke Inhalation Injury: A Review of the Literature

Objective: To review the clinical effects of nebulized heparin and N-acetylcysteine (NAC) in patients with smoke inhalation injury (IHI) and provide recommendations for use. Data Sources: A search of PubMed, MEDLINE, and Scopus databases was completed from database inception through April 15, 2020, using terms: heparin, acetylcysteine, smoke inhalation injury, and burn injury. Study Selection and Data Extraction: All studies pertaining to efficacy and safety of nebulized heparin and/or NAC for IHI in adult patients were evaluated. Reference lists were reviewed for additional publications. Nonhuman studies, non-English, and case report publications were excluded. Data Synthesis: Eight studies were included. Four demonstrated positive outcomes, 3 demonstrated no benefit or possible harm, and 1 assessed safety. Supporting trials treated patients within 48 hours of injury with 10 000 units of nebulized heparin with NAC for 7 days or until extubation. Two trials with negative findings treated patients within 72 hours, or unspecified, with 5000 units of nebulized heparin with NAC for 7 days, while the third used 25 000 units within 36 hours but was grossly underpowered for analysis. Clinical findings include reduced duration of mechanical ventilation and improved lung function with possible increase risk of pneumonia and no evidence of increased bleeding risk. Conclusions: Nebulized heparin may improve oxygenation and reduce duration of mechanical ventilation in IHI. If nebulized heparin is used, 10 000 units every 4 hours alternating with NAC and albuterol at 4-hour intervals is recommended. Sterile technique should be emphasized. Monitoring for bronchospasm or new-onset pneumonia should be considered.

Emerging therapies for smoke inhalation injury: a review

Background

Smoke inhalation injury increases overall burn mortality by up to 20 times. Current therapy remains supportive with a failure to identify an optimal or targeted treatment protocol for smoke inhalation injury. The goal of this review is to describe emerging therapies that are being developed to treat the pulmonary pathology induced by smoke inhalation injury with or without concurrent burn injury.

Main body

A comprehensive literature search was performed using PubMed (1995–present) for therapies not approved by the U.S. Food and Drug Administration (FDA) for smoke inhalation injury with or without concurrent burn injury. Therapies were divided based on therapeutic strategy. Models included inhalation alone with or without concurrent burn injury. Specific animal model, mechanism of action of medication, route of administration, therapeutic benefit, safety, mortality benefit, and efficacy were reviewed. Multiple potential therapies for smoke inhalation injury with or without burn injury are currently under investigation. These include stem cell therapy, anticoagulation therapy, selectin inhibition, inflammatory pathway modulation, superoxide and peroxynitrite decomposition, selective nitric oxide synthase inhibition, hydrogen sulfide, HMG-CoA reductase inhibition, proton pump inhibition, and targeted nanotherapies. While each of these approaches shows a potential therapeutic benefit to treating inhalation injury in animal models, further research including mortality benefit is needed to ensure safety and efficacy in humans.

Conclusions

Multiple novel therapies currently under active investigation to treat smoke inhalation injury show promising results. Much research remains to be conducted before these emerging therapies can be translated to the clinical arena.

Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns

BACKGROUND

The prevalence of acute respiratory distress syndrome (ARDS) in mechanically ventilated burn patients is 33%, with mortality varying from 11-46% depending on ARDS severity. Despite the new Berlin definition for ARDS, prompt bedside diagnosis is lacking. We developed and tested a bedside technique of fiberoptic-bronchoscopy-based optical coherence tomography (OCT) measurement of airway mucosal thickness (MT) for diagnosis of ARDS following smoke inhalation injury (SII) and burns.

METHODS

16 female Yorkshire pigs received SII and 40% thermal burns. OCT MT and PaO₂-to-FiO₂ ratio (PFR) measurements were taken at baseline, after injury, and at 24, 48, and 72h after injury.

RESULTS

Injury led to thickening of MT which was sustained in animals that developed ARDS. Significant correlations were found between MT, PFR, peak inspiratory pressure (PIP), and total infused fluid volume.

CONCLUSIONS

OCT is a useful tool to quantify MT changes in the airway following SII and burns. OCT may be effective as a diagnostic tool in the early stages of SII-induced ARDS and should be tested in humans.

Inhalation Injury in the Burned Patient

Inhalation injury causes a heterogeneous cascade of insults that increase morbidity and mortality among the burn population. Despite major advancements in burn care for the past several decades, there remains a significant burden of disease attributable to inhalation injury. For this reason, effort has been devoted to finding new therapeutic approaches to improve outcomes for patients who sustain inhalation injuries.The three major injury classes are the following: supraglottic, subglottic, and systemic. Treatment options for these three subtypes differ based on the pathophysiologic changes that each one elicits.Currently, no consensus exists for diagnosis or grading of the injury, and there are large variations in treatment worldwide, ranging from observation and conservative management to advanced therapies with nebulization of different pharmacologic agents.The main pathophysiologic change after a subglottic inhalation injury is an increase in the bronchial blood flow. An induced mucosal hyperemia leads to edema, increases mucus secretion and plasma transudation into the airways, disables the mucociliary escalator, and inactivates hypoxic vasocontriction. Collectively, these insults potentiate airway obstruction with casts formed from epithelial debris, fibrin clots, and inspissated mucus, resulting in impaired ventilation. Prompt bronchoscopic diagnosis and multimodal treatment improve outcomes. Despite the lack of globally accepted standard treatments, data exist to support the use of bronchoscopy and suctioning to remove debris, nebulized heparin for fibrin casts, nebulized N-acetylcysteine for mucus casts, and bronchodilators.Systemic effects of inhalation injury occur both indirectly from hypoxia or hypercapnia resulting from loss of pulmonary function and systemic effects of proinflammatory cytokines, as well as directly from metabolic poisons such as carbon monoxide and cyanide. Both present with nonspecific clinical symptoms including cardiovascular collapse. Carbon monoxide intoxication should be treated with oxygen and cyanide with hydroxocobalamin.Inhalation injury remains a great challenge for clinicians and an area of opportunity for scientists. Management of this concomitant injury lags behind other aspects of burn care. More clinical research is required to improve the outcome of inhalation injury.The goal of this review is to comprehensively summarize the diagnoses, treatment options, and current research.

Pathophysiology, research challenges, and clinical management of smoke inhalation injury

Smoke inhalation injury is a serious medical problem that increases morbidity and mortality after severe burns. However, relatively little attention has been paid to this devastating condition, and the bulk of research is limited to preclinical basic science studies. Moreover, no worldwide consensus criteria exist for its diagnosis, severity grading, and prognosis. Therapeutic approaches are highly variable depending on the country and burn centre or hospital. In this Series paper, we discuss understanding of the pathophysiology of smoke inhalation injury, the best evidence-based treatments, and challenges and future directions in diagnostics and management.

Automatic airway wall segmentation and thickness measurement for long-range optical coherence tomography images

We present an automatic segmentation method for the delineation and quantitative thickness measurement of multiple layers in endoscopic airway optical coherence tomography (OCT) images. The boundaries of the mucosa and the sub-mucosa layers are accurately extracted using a graph-theory-based dynamic programming algorithm. The algorithm was tested with sheep airway OCT images. Quantitative thicknesses of the mucosal layers are obtained automatically for smoke inhalation injury experiments.

Integrity of airway epithelium in pediatric burn autopsies: Association with age and extent of burn injury

This study examines the structural integrity of the airway epithelium in autopsy tissues from pediatric burn subjects.

METHODS

A semi-quantitative score for the degree of airway epithelial integrity was made for seventy- two pediatric burn autopsies. Multivariate ordinal logistic regression was performed to identify relationships between epithelial integrity and conditions related to tissue fixation, time of death after injury, age, total body surface area burn (TBSA), extent of 3rd degree burn, presence of inhalation injury, ventilator days and pneumonia.

RESULTS

No significant difference in epithelial integrity scores was identified between burn only cases and those with inhalation injury. Significant correlations with bronchiolar epithelial integrity scores were identified for age, p=0.02, and percent 3rd degree burn, p=0.02. There was no significant relationship between epithelial integrity and time between death and autopsy, p>0.44.

CONCLUSIONS

Airway epithelial loss seen in autopsy tissue is not simply an artifact of tissue fixation. The degree of compromise correlates most strongly with age and degree of burn. Further studies are needed to identify physiological or critical care factors following burn injury that contribute to compromise in the structural and functional properties of the airway epithelium.

Comparison of virtual bronchoscopy to fiber-optic bronchoscopy for assessment of inhalation injury severity

PURPOSE

Compare virtual bronchoscopy (VB) to fiberoptic bronchoscopy (FOB) for scoring smoke inhalation injury (SII).

METHODS

Swine underwent computerized tomography (CT) with VB and FOB before (0) and 24 and 48 h after SII. VB and FOB images were scored by 5 providers off line.

RESULTS

FOB and VB scores increased over time (p<0.001) with FOB scoring higher than VB at 0 (0.30±0.79 vs. 0.03±0.17), 24 h (4.21±1.68 vs. 2.47±1.50), and 48h (4.55±1.83 vs. 1.94±1.29). FOB and VB showed association with PaO2-to-FiO2 ratios (PFR) with areas under receiver operating characteristic curves (ROC): for PFR≤300, VB 0.830, FOB 0.863; for PFR≤200, VB 0.794, FOB 0.825; for PFR≤100, VB 0.747, FOB 0.777 (all p<0.001). FOB showed 80.3% specificity, 77% sensitivity, 88.8% negative-predictive value (NPV), and 62.3% positive-predictive value (PPV) for PFR≤300 and VB showed 67.2% specificity, 85.5% sensitivity, 91.3% NPV, and 53.4% PPV.

CONCLUSIONS

VB provided similar injury severity scores to FOB, correlated with PFR, and reliably detected airway narrowing. VB performed during admission CT may be a useful screening tool specifically to demonstrate airway narrowing induced by SII.

In vivo detection of inhalation injury in large airway using three-dimensional long-range swept-source optical coherence tomography

We report on the feasibility of using long-range swept-source optical coherence tomography (OCT) to detect airway changes following smoke inhalation in a sheep model. The long-range OCT system (with axial imaging range of 25 mm) and probe are capable of rapidly obtaining a series of high-resolution full cross-sectional images and three-dimensional reconstructions covering 20-cm length of tracheal and bronchial airways with airway diameter up to 25 mm, regardless of the position of the probe within the airway lumen. Measurements of airway thickness were performed at baseline and postinjury to show mucosal thickness changes following smoke inhalation.

Nebulized anticoagulants for acute lung injury - a systematic review of preclinical and clinical investigations

Background

Data from interventional trials of systemic anticoagulation for sepsis inconsistently suggest beneficial effects in case of acute lung injury (ALI). Severe systemic bleeding due to anticoagulation may have offset the possible positive effects. Nebulization of anticoagulants may allow for improved local biological availability and as such may improve efficacy in the lungs and lower the risk of systemic bleeding complications.

Method

We performed a systematic review of preclinical studies and clinical trials investigating the efficacy and safety of nebulized anticoagulants in the setting of lung injury in animals and ALI in humans.

Results

The efficacy of nebulized activated protein C, antithrombin, heparin and danaparoid has been tested in diverse animal models of direct (for example, pneumonia-, intra-pulmonary lipopolysaccharide (LPS)-, and smoke inhalation-induced lung injury) and indirect lung injury (for example, intravenous LPS- and trauma-induced lung injury). Nebulized anticoagulants were found to have the potential to attenuate pulmonary coagulopathy and frequently also inflammation. Notably, nebulized danaparoid and heparin but not activated protein C and antithrombin, were found to have an effect on systemic coagulation. Clinical trials of nebulized anticoagulants are very limited. Nebulized heparin was found to improve survival of patients with smoke inhalation-induced ALI. In a trial of critically ill patients who needed mechanical ventilation for longer than two days, nebulized heparin was associated with a higher number of ventilator-free days. In line with results from preclinical studies, nebulization of heparin was found to have an effect on systemic coagulation, but without causing systemic bleedings.

Conclusion

Local anticoagulant therapy through nebulization of anticoagulants attenuates pulmonary coagulopathy and frequently also inflammation in preclinical studies of lung injury. Recent human trials suggest nebulized heparin for ALI to be beneficial and safe, but data are very limited.

Comparison of airway pressure release ventilation to conventional mechanical ventilation in the early management of smoke inhalation injury in swine

OBJECTIVE

The role of airway pressure release ventilation in the management of early smoke inhalation injury has not been studied. We compared the effects of airway pressure release ventilation and conventional mechanical ventilation on oxygenation in a porcine model of acute respiratory distress syndrome induced by wood smoke inhalation.

DESIGN

Prospective animal study.

SETTING

Government laboratory animal intensive care unit.

PATIENTS

Thirty-three Yorkshire pigs.

INTERVENTIONS

Smoke inhalation injury.

MEASUREMENTS AND MAIN RESULTS

Anesthetized female Yorkshire pigs (n = 33) inhaled room-temperature pine-bark smoke. Before injury, the pigs were randomized to receive conventional mechanical ventilation (n = 15) or airway pressure release ventilation (n = 12) for 48 hrs after smoke inhalation. As acute respiratory distress syndrome developed (PaO2/Fio2 ratio <200), plateau pressures were limited to <35 cm H2O. Six uninjured pigs received conventional mechanical ventilation for 48 hrs and served as time controls. Changes in PaO2/Fio2 ratio, tidal volume, respiratory rate, mean airway pressure, plateau pressure, and hemodynamic variables were recorded. Survival was assessed using Kaplan-Meier analysis. PaO2/Fio2 ratio was lower in airway pressure release ventilation vs. conventional mechanical ventilation pigs at 12, 18, and 24 hrs (p < .05) but not at 48 hrs. Tidal volumes were lower in conventional mechanical ventilation animals between 30 and 48 hrs post injury (p < .05). Respiratory rates were lower in airway pressure release ventilation at 24, 42, and 48 hrs (p < .05). Mean airway pressures were higher in airway pressure release ventilation animals between 6 and 48 hrs (p < .05). There was no difference in plateau pressures, hemodynamic variables, or survival between conventional mechanical ventilation and airway pressure release ventilation pigs.

CONCLUSIONS

In this model of acute respiratory distress syndrome caused by severe smoke inhalation in swine, airway pressure release ventilation-treated animals developed acute respiratory distress syndrome faster than conventional mechanical ventilation-treated animals, showing a lower PaO2/Fio2 ratio at 12, 18, and 24 hrs after injury. At other time points, PaO2/Fio2 ratio was not different between conventional mechanical ventilation and airway pressure release ventilation.

ACUTE BRONCHIAL OBSTRUCTION IN SHEEP: HISTOPATHOLOGY AND GLAND CYTOKINE EXPRESSION

An ovine model of smoke inhalation and burn (S+B) injury models the pathophysiology of these injuries in humans. This study examines the degree of airway obstruction, associated histopathology, and bronchial gland cell expression of cytokines during the first 24 hours after S+B injury in sheep. Changes in the mean degree of obstruction were limited to the bronchial airways, showing significant increases in obstruction with time, P<.05. At 4 hours after injury, the obstructive material was predominantly mucus, with neutrophils clustered around and within gland acini. At 8 to 24 hours, bronchial obstruction was characterized by increased inflammatory cell accumulation. Immunohistochemical results showed that gland cells constitutively express and secrete interleukin (IL)-1beta, and that after injury there is an increase in the percentage of gland cells staining for IL-1alpha, IL-8, and tumor necrosis factor (TNF)-alpha, P<.05.

Upper airway mucus deposition in lung tissue of burn trauma victims

Previous study in an ovine model of smoke inhalation and burn (S + B) injury has shown distal migration of upper airway mucus. This study examines the localization of an upper airway gland specific mucus, mucin 5B (MUC5B) in lung autopsy tissues of burn-only injury and in victims of S + B injury. We hypothesize that victims with S + B injury would exhibit increased distal migration of MUC5B than that seen in victims of burn-only injury. Autopsy lung tissue from victims of burn injury alone (n = 38) and combined S + B injury (n = 22) were immunostained for MUC5B. No normal lung tissues were included in the study. Semiquantitative analysis of the extent of MUC5B in bronchioles and parenchyma was performed on masked slides. Irrespective of injury conditions, all victims showed MUC5B in bronchioles. Mucin 5B was seen in the parenchyma except in two burn victims. No statistically significant difference was seen in the mean bronchiolar and parenchyma MUC5B scores between S + B and burn-only victims (P > 0.05). No strong statistical correlation of MUC5B scores with days postinjury or to the number of ventilatory days was evident. The percentage of pneumonia, identified histologically, was also similar between study groups. This study did not confirm our results in an ovine model of S + B injury. In contrast, virtually all pediatric burn victims, regardless of concomitant inhalation injury, showed MUC5B in their bronchioles and parenchyma. Increased mucus synthesis and/or impaired mucociliary function may contribute to the pulmonary pathophysiology associated with burn injury.

Aerosolized anticoagulants ameliorate acute lung injury in sheep after exposure to burn and smoke inhalation

OBJECTIVE

Acute lung injury is a detrimental complication for victims of burn accidents. Airway obstruction plays an important role in pulmonary dysfunction in these patients. In this study, we tested the hypothesis that aerosolized anticoagulants will reduce the degree of airway obstruction and improve pulmonary function in sheep with severe combined burn and smoke inhalation injury by preventing the formation of airway fibrin clots.

DESIGN

Prospective, randomized, controlled, experimental animal study.

SETTING

Investigational intensive care unit at a university hospital.

SUBJECTS

Adult female sheep.

INTERVENTIONS

After 7 days of surgical recovery, sheep were given a cutaneous burn (40% of total body surface, third degree) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anesthesia. After injury, sheep were placed on ventilators and resuscitated with lactated Ringer's solution. Sheep were randomly divided into five groups: sham, noninjured and nontreated (n = 6); control, injured and aerosolized with saline (n = 6); recombinant human antithrombin (rhAT) + heparin, injured and aerosolized with rhAT (290 units for each) and heparin (10,000 units for each) (n = 6); rhAT, injured and aerosolized with rhAT alone (290 units for each; n = 5); and heparin, injured and aerosolized with heparin alone (10,000 units for each; n = 5). rhAT and heparin were aerosolized every 4 hrs, starting at 2 hrs postinjury.

MEASUREMENTS AND MAIN RESULTS

Cardiopulmonary hemodynamics were monitored during a 48-hr experimental time period. Control sheep developed multiple signs of acute lung injury. This pathophysiology included decreased pulmonary gas exchange and lung compliance, increased pulmonary edema, and extensive airway obstruction. These variables were stable in sham animals. The aerosolization of rhAT or heparin alone did not significantly improve deteriorated pulmonary gas exchange. However, aerosolization of these anticoagulants in combination significantly attenuated all the observed pulmonary pathophysiology.

CONCLUSIONS

The results provide definitive evidence that aerosolized rhAT and heparin in combination may be a novel treatment strategy for pulmonary pathology in burn victims with smoke inhalation injury.

Use of high-frequency percussive ventilation in inhalation injuries

Inhalation injury causes significant morbidity and mortality, accounting for nearly 80% of non-fire-related deaths and affecting nearly 25% of all patients hospitalized with thermal injury. High-frequency percussive ventilation (HFPV) has been reported to decrease both the incidence of pulmonary barotrauma and pneumonia in inhalation injury. It has evolved into a ventilatory modality promoted to rapidly remove airway secretions and improve survival of patients with smoke inhalation injury. From 1997 to 2005, a total of 92 patients with inhalation injury were treated with HFPV. This group was compared with 130 patients treated with conventional mechanical ventilation between 1997 and 2005. The diagnosis of inhalation injury was made on admission, based on the following clinical criteria: injury in a closed space, carbonaceous sputum, and/or positive bronchoscopy (presence of carbonaceous deposits, erythema or ulceration). Both modes of ventilation were begun within 24 hours of injury. Both groups were similar with respect to demographics and injury severity. The mean number of ventilator days, days in the intensive care unit, length of stay, and incidence of pneumonia did not differ significantly between groups. Twenty-six of 92 (28%) patients treated with HFPV, and 56 of 130 with conventional mechanical ventilation (43%) died. There was a significant decrease in both overall morbidity and mortality in the subset of patients with < or = 40% TBSA treated with HFPV. Future randomized, controlled trials are needed to determine the precise role of HFPV in the treatment of inhalation injuries.

Exacerbation of wood smoke-induced acute lung injury by mechanical ventilation using moderately high tidal volume in mice

We investigated the effects of mechanical ventilation with a moderately high tidal volume (VT) on acute lung injury (ALI) induced by wood smoke inhalation in anesthetized mice. Animals received challenges of air, 30 breaths of smoke (30SM) or 60 breaths of smoke (60SM) and were then ventilated with a VT of 10 ml/kg (10VT) or 16 ml/kg (16VT). After 4-h mechanical ventilation, the bronchoalveolar-capillary permeability, pulmonary infiltration of inflammatory cells, total lung injury score and pulmonary expressions of interleukin-1beta and macrophage inflammatory protein-2 mRNA and proteins in the 30SM+16VT and 60SM+16VT groups were greater than those in the 30SM+10VT and 60SM+10VT groups, respectively. Additionally, the wet/dry weight ratio of lung tissues and lung epithelial cell apoptosis in the 60SM+16VT group were greater than those in the 60SM+10VT group. These differences between the 16VT and 10VT groups were not seen in animals with air challenge. Thus, mechanical ventilation with a moderately high VT in mice exacerbates ALI induced by wood smoke inhalation.

Fatal inhalation injury caused by airway fire during tracheostomy

A 45-year-old man needed emergency tracheostomy and cranioplasty. He was intubated with a cuffed oral polyvinylchloride endotracheal tube and ventilated with 100% oxygen before tracheal incision. During opening of the trachea using diathermy, a popping sound was heard and flames originating from the tracheal incision were observed. The endotracheal tube was charred and its lumen had melted. Immediately after the incident, bronchofibroscopic examination revealed inhalation injury. After remaining for 8 weeks in hospital, the patient was transferred to a health care centre, where he was found dead in his bed.

Factors that Predict the Need for Intubation in Patients with Smoke Inhalation Injury

Early identification of smoke inhalation patients who will require intubation is crucial. We conducted a retrospective chart review to identify predictors of respiratory distress in patients who present with smoke inhalation injury. Our study involved 41 patients who had been treated in the emergency room at a regional burn center. Eight of these patients required intubation. Intubation was positively correlated with physical examination findings of soot in the oral cavity (p < 0.001), facial burns (p = 0.025), and body burns (p = 0.025). The need for intubation was also predicted by fiberoptic laryngoscopic findings of edema of either the true vocal folds (p < 0.001) or the false vocal folds (p < 0.01). No statistically significant correlation was found between intubation and any of the classic symptoms of smoke inhalation: stridor, hoarseness, drooling, and dysphagia (all p = 1.0). Also, multivariate analysis revealed that facial burns correlated significantly with edema of the true vocal folds (p = 0.01) and body burns correlated significantly with edema of both the true (p = 0.047) and false (p = 0.003) vocal folds. We conclude that patients with soot in the oral cavity, facial burns, and/or body burns should be monitored closely because these findings indicate a higher likelihood of laryngeal edema and the need for intubation.

Management of multiple burn casualties from the Volendam disaster in the emergency departments of general hospitals

OBJECTIVE

To establish the level of medical care provided in the emergency department of general hospitals to the victims of the Volendam café fire on 1 January 2001.

METHODS

A retrospective review was done based on a standardized chart, for all victims seen at the emergency departments of 19 hospitals. Diagnostic findings and logistic aspects were inventoried. Treatment described in the Emergency Management of Severe Burns protocol was used as a gold standard against which the care provided to the victims was assessed.

RESULTS

Data from 233 patients were included in the analysis. The documentation rate was low. Suspected inhalation injury and burns were the most frequently documented diagnoses. Most patients with suspected inhalation injury, for whom treatment records were available, received oxygen therapy (81%). Intubation was performed in 43% of patients with suspected inhalation injury and 14% of the remaining patients required intubation after admission to the intensive care unit. Most patients with circulatory problems (83%) and/or more than 15% of total body surface area burned (97%), for whom treatment records were available, received intravenous lines. Pain treatment seemed to have had low priority. Two patients (3%) were re-admitted after having been released earlier from the emergency department.

CONCLUSION

Treatment and triage of the burn casualties after the Volendam café fire was adequate. The documentation rate was low. Not all steps in diagnosis and treatment may be of equal importance in disaster circumstances.

[Primary treatment of burn patients]

Burn injuries can be caused by thermal, electrical, chemical, or mechanical trauma or radiation and are relatively rare, as they represent only about 1% of all emergencies. They are caused by accidents at home, during recreational activities, or in the occupational environment. Minor burn traumas are much more common than severe burn injuries with their systemic and potentially life-threatening effects. Altogether, these circumstances may result in a lack of routine for treating such injuries properly by physicians and their colleagues in the emergency room or intensive care unit. A clearly outlined concept for preclinical and clinical treatment can be the keystone of successful further clinical progress. The following article summarizes the current guidelines for first medical aid at the injury scene, burn stabilization and assessment in the emergency room, and the interdisciplinary approach for further clinical care. The treatment of dermatologic emergencies (acute epidermolytic syndromes) or caustic injuries by chemical agents is similar to the treatment of burn victims in many aspects but must be adapted in selected cases.

Is high PEEP low volume ventilation in burn patients beneficial? A retrospective study of 61 patients

In burn care lung damage by inhalation injury is a major cause of mortality in burn patients. In the field of intensive care medicine ventilation strategies to reduce lung injury caused by ventilation are under investigation. The promising results of the application of pressure controlled high PEEP low volume (HPLV) ventilation prompted us to use this ventilation strategy in our burn ICU. To establish whether this ventilation regime is beneficial the charts of 61 consecutive patients needing artificial respiration were reviewed. A scoring system for PEEP level and tidal volume was developed and treatment groups with high PEEP and low volume and low PEEP high volume regimes were compared. No statistically significant differences could be found when comparing treatment versus mortality, the number of pulmonary complications or incidence of pneumothoraces. However, the trend showed a benefit in mortality for patients with an ABSI scoring up to 9, but at the same time pulmonary complications increase. The Horovitz oxygenation index showed no advantage for the HPLV Group. In a separate analysis we found a significant correlation between absolute PEEP and mortality. The correlation between PEEP level and mortality is a dynamic factor predicting outcome, This not been described yet and can be an addition to the static ABSI score. Differences between ventilation strategies were not as evident as expected in this retrospective study, so prospective randomized studies are needed.

AEROSOLIZED TISSUE PLASMINOGEN INHIBITOR IMPROVES PULMONARY FUNCTION IN SHEEP WITH BURN AND SMOKE INHALATION

Acute respiratory distress syndrome is a major complication in patients with thermal injury. The obstruction of the airway by cast material, composed in part of fibrin, contributes to deterioration of pulmonary gas exchange. We tested the effect of aerosol administration of tissue plasminogen activator, which lyses fibrin clots, on acute lung injury in sheep that had undergone combined burn/smoke inhalation injury. Anesthetized sheep were given a 40% total body surface, third degree burn and were insufflated with cotton smoke. Tissue plasminogen activator (TPA) was nebulized every 4 h at 1 or 2 mg for each nebulization, beginning 4 h after injury. Injured but untreated control sheep developed multiple symptoms of acute respiratory distress syndrome: decreased pulmonary gas exchange, increased pulmonary edema, and extensive airway obstruction. These control animals also showed increased pulmonary transvascular fluid flux and increased airway pressures. These variables were all stable in sham animals. Nebulization of saline or 1 mg of TPA only slightly improved measures of pulmonary function. Treatment of injured sheep with 2 mg of TPA attenuated all the pulmonary abnormalities noted above. The results provide evidence that clearance of airway obstructive cast material is crucial in managing acute respiratory distress syndrome resulting from combined burn and smoke inhalation injury.

Airway obstruction in sheep with burn and smoke inhalation injuries

The goals of this study were (i) to compare the degree and (ii) temporal changes in airway obstruction in sheep with pulmonary injury induced by smoke inhalation and/or burn; (iii) to qualitatively assess the cellular and mucous content of obstructive material; and (iv) to statistically assess a possible relationship between the degree of airway obstruction and pulmonary dysfunction. Using masked histologic slides, we estimated the degree of luminal obstruction in all cross-sectioned airways. The mean degree of bronchial, bronchiolar, and terminal bronchiolar obstruction was significantly greater in animals with smoke injury alone or combined smoke inhalation and burn (S+B) injury, compared with animals with burn injury alone or uninjured animals (P < 0.05). In S+B animals, the degree of bronchial obstruction was maximal at 24 h, with a progressive decrease over 72 h. In contrast, the degree of bronchiolar obstruction increased over time. Qualitatively, bronchial casts were largely composed of mucus at early times after injury, whereas neutrophils were the principal component of bronchiolar obstructive material. Localization of specific mucin subtypes in S+B tissues suggests that increasing bronchiolar obstruction is derived, in part, from upper airway material. Multiple linear regression analysis of airway obstruction scores compared with PaO2/FIO2 values showed a correlation coefficient of r = 0.76, with bronchial and bronchiolar scores predictive of PaO2/FIO2, (P < 0.05). These results suggest that strategies to remove or decrease formation of upper airway obstructive material may reduce its deposition into small airways and parenchyma and may improve respiratory function in victims of smoke inhalation injury.