Clinical management of casualties exposed to lung damaging agents: a critical review

Countermeasures against Pulmonary Threat Agents

Inhaled toxicants are used for diverse purposes, ranging from industrial applications such as agriculture, sanitation, and fumigation to crowd control and chemical warfare, and acute exposure can induce lasting respiratory complications. The intentional release of chemical warfare agents (CWAs) during World War I caused life-long damage for survivors, and CWA use is outlawed by international treaties. However, in the past two decades, chemical warfare use has surged in the Middle East and Eastern Europe, with a shift toward lung toxicants. The potential use of industrial and agricultural chemicals in rogue activities is a major concern as they are often stored and transported near populated areas, where intentional or accidental release can cause severe injuries and fatalities. Despite laws and regulatory agencies that regulate use, storage, transport, emissions, and disposal, inhalational exposures continue to cause lasting lung injury. Industrial irritants (e.g., ammonia) aggravate the upper respiratory tract, causing pneumonitis, bronchoconstriction, and dyspnea. Irritant gases (e.g., acrolein, chloropicrin) affect epithelial barrier integrity and cause tissue damage through reactive intermediates or by direct adduction of cysteine-rich proteins. Symptoms of CWAs (e.g., chlorine gas, phosgene, sulfur mustard) progress from airway obstruction and pulmonary edema to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which results in respiratory depression days later. Emergency treatment is limited to supportive care using bronchodilators to control airway constriction and rescue with mechanical ventilation to improve gas exchange. Complications from acute exposure can promote obstructive lung disease and/or pulmonary fibrosis, which require long-term clinical care. SIGNIFICANCE STATEMENT: Inhaled chemical threats are of growing concern in both civilian and military settings, and there is an increased need to reduce acute lung injury and delayed clinical complications from exposures. This minireview highlights our current understanding of acute toxicity and pathophysiology of a select number of chemicals of concern. It discusses potential early-stage therapeutic development as well as challenges in developing countermeasures applicable for administration in mass casualty situations.

Human chlorine gas exposition and its management - an umbrella review on human data

Even though exposure to chlorine gas has been quite frequent in the past few decades, no specific antidotes exist. This umbrella review aimed to investigate possible recommendations for treatment after a chlorine gas exposure. A published systematic review protocol that adapted the existing Navigation Guide methodology was used for including studies without comparator. Using PubMed, Web of Science, Google scholar for all potentially relevant systematic reviews, two authors independently included papers and extracted data. The risk of bias and quality of evidence was assessed by two independent review teams blinded to each other. A qualitative summary of the study findings was conducted for this overview. There were a total of 31 studies, from 4 systematic reviews, that met the inclusion criteria, comprising 3567 reported cases, with only two studies with comparators. Six studies reported pre-hospital management of patients after exposure to chlorine gas. With respect to the treatment, the most used were oxygen therapy, endotracheal intubation, β2-agonists, and corticosteroids. This review found a high quality of evidence for the effectiveness of pre-hospital management (i.e. exposure cessation) on survival at hospital discharge after exposure to chlorine gas. Oxygen administration was effective with moderate quality of evidence, as well as other types of treatment (e.g. β2, corticosteroids), but with a low level of evidence. This umbrella review highlighted the low level of evidence for existing treatments of chlorine gas poisoning. This project was supported by the French Pays de la Loire region and Angers Loire Métropole (TEC-TOP project). There is no award/grant number. The review protocol was registered on PROSPERO under the registration number CRD42021231524.

Mechanism of Phosgene-Induced Acute Lung Injury and Treatment Strategy

Phosgene (COCl₂) was once used as a classic suffocation poison and currently plays an essential role in industrial production. Due to its high toxicity, the problem of poisoning caused by leakage during production, storage, and use cannot be ignored. Phosgene mainly acts on the lungs, causing long-lasting respiratory depression, refractory pulmonary edema, and other related lung injuries, which may cause acute respiratory distress syndrome or even death in severe cases. Due to the high mortality, poor prognosis, and frequent sequelae, targeted therapies for phosgene exposure are needed. However, there is currently no specific antidote for phosgene poisoning. This paper reviews the literature on the mechanism and treatment strategies to explore new ideas for the treatment of phosgene poisoning.

Phosgene: toxicology, animal models, and medical countermeasures

Phosgene is a gas crucial to industrial chemical processes with widespread production (∼1 million tons/year in the USA, 8.5 million tons/year worldwide). Phosgene's high toxicity and physical properties resulted in its use as a chemical warfare agent during the First World War with a designation of CG ('Choky Gas'). The industrial availability of phosgene makes it a compound of concern as a weapon of mass destruction by terrorist organizations. The hydrophobicity of phosgene exacerbates its toxicity often resulting in a delayed toxidrome as the upper airways are moderately irritated; by the time symptoms appear, significant damage has occurred. As the standard of care for phosgene intoxication is supportive therapy, a pressing need for effective therapeutics and treatment regimens exists. Proposed toxicity mechanisms for phosgene based on human and animal exposures are discussed. Whereas intermediary components in the phosgene intoxication pathways are under continued discussion, generation of reactive oxygen species and oxidative stress is a common factor. As animal models are required for the study of phosgene and for FDA approval via the Animal Rule; the status of existing models and their adherence to Haber's Rule is discussed. Finally, we review the continued search for efficacious therapeutics for phosgene intoxication; and present a rapid post-exposure response that places exogenous human heat shock protein 72, in the form of a cell-penetrating fusion protein (Fv-HSP72), into lung tissues to combat apoptosis resulting from oxidative stress. Despite significant progress, additional work is required to advance effective therapeutics for acute phosgene exposure.

Severe Acute Lung Injury Related to COVID-19 Infection: A Review and the Possible Role for Escin

Acute lung injury (ALI) represents the most severe form of the viral infection sustained by coronavirus disease 2019 (COVID-19). Today, it is a pandemic infection, and even if several compounds are used as curative or supportive treatment, there is not a definitive treatment. In particular, antiviral treatment used for the treatment of several viral infections (eg, hepatitis C, HIV, Ebola, severe acute respiratory syndrome-coronavirus) are today used with a mild or moderate effect on the lung injury. In fact, ALI seems to be related to the inflammatory burst and release of proinflammatory mediators that induce intra-alveolar fibrin accumulation that reduces the gas exchange. Therefore, an add-on therapy with drugs able to reduce inflammation, edema, and cell activation has been proposed as well as a treatment with interferon, corticosteroids or monoclonal antibodies (eg, tocilizumab). In this article reviewing literature data related to the use of escin, an agent having potent anti-inflammatory and anti-viral effects in lung injury, we suggest that it could represent a therapeutic opportunity as add-on therapy in ALI related to COVID-19 infection.

Development of an acute, short-term exposure model for phosgene

Phosgene is classified as a chemical warfare agent, yet data on its short-duration high concentration toxicity in a nose-only exposure rat model is sparse and inconsistent. Hence, an exposure system for short-term/high concentration exposure was developed and characterized. Herein, we report the median lethal concentration (LC₅₀) for a 10-min nasal exposure of phosgene in a 24-h rat survival model. Male Wistar rats (Envigo) weighing 180-210 g on the day of exposure, were exposed to phosgene gas via nose-only inhalation using a system specifically designed to allow the simultaneous exposure and quantification of phosgene. After 24 h, the surviving rats were euthanized, the lung/body mass ratio determined, and lung tissues analyzed for histopathology. Increased terminal airway edema in the lungs located primarily at the alveoli (resulting in an increased lung/body mass ratio) coincided with the observed mortality. An LC₅₀ value of 129.2 mg/m³ for a 10-min exposure was determined. Furthermore, in agreement with other highly toxic compounds, this study reveals a LC₅₀ concentration value supportive of a nonlinear toxic load model, where the toxic load exponent is >1 (n_e = 1.17). Thus, in line with other chemical warfare agents, phosgene toxicity is predicted to be more severe with short-duration, high-concentration exposures than long-duration, low-concentration exposures. This model is anticipated to be refined and developed to screen novel therapeutics against relevant short-term high concentration phosgene exposures expected from a terrorist attack, battlefield deployment, or industrial accident.

Chemical Agents in Disaster: Care and Management in the Intensive Care Unit

Chemical agents of warfare are divided into lung agents, blood agents, vesicants, and nerve agents. Intensivists must familiarize themselves with the clinical presentation and management principles in the event of a chemical attack. Key principles in management include aggressive supportive care and early administration of specific antidotes, if available. Management includes proper personal protection for critical care providers. Patients may make complete recovery with aggressive supportive care, even if they appear to have a poor prognosis. Hospitals must have an emergency response disaster plan in place to deal with all potential causes of disasters, including illnesses resulting from chemical agents.

Comparison of airway response in naïve and ovalbumin-sensitized mice during short-term inhalation exposure to chlorine

OBJECTIVE

It has been suggested that asthmatics are more susceptible than healthy individuals to airborne irritating chemicals in general. However, there is limited human data available to support this hypothesis due to ethical and practical difficulties. We explored a murine model of ovalbumin (OVA)-induced airway inflammation to study susceptibility during acute exposure to chemicals with chlorine as a model substance.

METHODS

Naïve and OVA sensitized female BALB/c mice were exposed to chlorine at four different concentrations (0, 5, 30 and 80 ppm) for 15 minutes with online recording of the respiratory function by plethysmography. The specific effects on respiratory mechanics, inflammatory cells and inflammatory mediators (cytokines and chemokines) of the airways were measured 24 hours after the chlorine exposure as well as histopathological examination of the lungs.

RESULTS

Similar concentration-dependent reductions in respiratory frequency were seen in the two groups, with a 50% reduction (RD₅₀) slightly above 5 ppm. Decreased body weight 24 hours after exposure to 80 ppm was also observed in both groups. Naïve, but not OVA-sensitized, mice showed increased bronchial reactivity and higher number of neutrophils in bronchoalveolar lavage fluid at 80 ppm.

CONCLUSIONS

The results do not support an increased susceptibility to chlorine among OVA-sensitized mice. This animal model, which represents a phenotype of eosinophilic airway inflammation, seems unsuitable to study susceptibility to inhalation of irritants in relation to asthma.

Deliberate exposure of humans to chlorine-the aftermath of Ebola in West Africa

Background

During the recent Ebola outbreak, spraying of the environment and humans, including healthcare workers, with chlorine was wide spread in affected African countries; adverse clinical effects are reported here.

Methods

A cross sectional survey by interview of 1550 volunteers consisting of 500 healthcare workers (HCW), 550 Ebola survivors (EVD) and 500 quarantined asymptomatic Ebola contacts (NEVD) was conducted. Demographics, frequency of exposure to chlorine, clinical condition after chlorine exposure particularly eye, respiratory and skin conditions were noted. The length of time HCWs worked in Ebola Treatment Units (ETU), and use of personal protective equipment was recorded. Verbal consent was obtained from all participants and all responses remained anonymous. Permission and assistance from the guardian or parent was sought for those below 18 years of age.

Results

493/500 HCW, 550/550 EVD and 477/500 NEVD were sprayed at least once with 0 · 5 % chlorine. Following even a single exposure, an increase in the number of eye (all three groups) and respiratory symptoms (in HCW & EVD) was reported (p < 0 · 001); after multiple exposure, respiratory and skin symptoms increased. In HCW, multiple vs single exposure was associated with an increase in respiratory (OR = 32 (95 % CI 22 –49) p < 0.001), eyes (OR = 30 (95 % CI 21 –43) p < 0.001) and skin conditions (OR = 22 (95 % CI 15–32) p < 0.001). The available personal protective equipment neither reduced nor prevented the adverse effects of chlorine.

Conclusion

Reported exposure to chlorine has usually been accidental. Despite the lack of evidence as a recognised outbreak control measure, deliberate exposure of humans to chlorine spray was wide spread in Africa during the Ebola epidemic resulting in serious detrimental health effects on humans. We strongly recommend that this practice be banned and that alternative safer methods be used.

Targeted heat shock protein 72 for pulmonary cytoprotection

Heat shock protein 72 (HSP72) is perhaps the most important member of the HSP70 family of proteins, given that it is induced in a wide variety of tissues and cells to combat stress, particularly oxidative stress. Here, we review independent observations of the critical role this protein plays as a pulmonary cytoprotectant and discuss the merits of developing HSP72 as a therapeutic for rapid delivery to cells and tissues after a traumatic event. We also discuss the fusion of HSP72 to a cell-penetrating single-chain Fv antibody fragment derived from mAb 3E10, referred to as Fv-HSP70. This fusion construct has been validated in vivo in a cerebral infarction model and is currently in testing as a clinical therapeutic to treat ischemic events and as a fieldable medical countermeasure to treat inhalation of toxicants caused by terrorist actions or industrial accidents.

Pathology, toxicology, and latency of irritant gases known to cause bronchiolitis obliterans disease: Does diacetyl fit the pattern?

Bronchiolitis obliterans (BO) is a rare disease involving concentric bronchiolar fibrosis that develops rapidly following inhalation of certain irritant gases at sufficiently high acute doses. While there are many potential causes of bronchiolar lesions involved in a variety of chronic lung diseases, failure to clearly define the clinical features and pathological characteristics can lead to ambiguous diagnoses. Irritant gases known to cause BO follow a similar pathologic process and time course of disease onset in humans. Studies of inhaled irritant gases known to cause BO (e.g., chlorine, hydrochloric acid, ammonia, nitrogen oxides, sulfur oxides, sulfur or nitrogen mustards, and phosgene) indicate that the time course between causal chemical exposures and development of clinically significant BO disease is typically limited to a few months. The mechanism of toxic action exerted by these irritant gases generally involves widespread and severe injury of the epithelial lining of the bronchioles that leads to acute respiratory symptoms which can include lung edema within days. Repeated exposures to inhaled irritant gases at concentrations insufficient to cause marked respiratory distress or edema may lead to adaptive responses that can reduce or prevent severe bronchiolar fibrotic changes. Risk of BO from irritant gases is driven substantially by toxicokinetics affecting concentrations occurring at the bronchiolar epithelium. Highly soluble irritant gases that cause BO like ammonia generally follow a threshold-dependent cytotoxic mechanism of action that at sufficiently high doses results in severe inflammation of the upper respiratory tract and the bronchiolar epithelium concurrently. This is followed by acute respiratory distress, pulmonary edema, and post inflammatory concentric fibrosis that become clinically obvious within a few months. In contrast, irritant gases with lower solubility like phosgene also follow a threshold-dependent mechanism of cytotoxicity action but can exhibit more insidious and isolated bronchiolar tissue damage with a similar latency to fibrosis. To date, animal and human studies on the highly soluble gas, diacetyl, have not identified a coherent pattern of pathology and latency that would be expected based on studies of other known causes of bronchiolitis obliterans disease.

Corticosteroids found ineffective for phosgene-induced acute lung injury in rats

Various therapeutic regimes have been proposed with limited success for treatment of phosgene-induced acute lung injury (P-ALI). Corticoids were shown to be efficacious against chlorine-induced lung injury but there is still controversy whether this applies also to P-ALI. This study investigates whether different regimen of curatively administered budesonide (BUD, 10 mg/kg bw, i.p. bid; 100 mg/m(3)×30 min, nose-only inhalation), mometasone (MOM, 3 mg/kg bw, i.p. bid) and dexamethasone (DEX, 10, 30 mg/kg bw, i.p. bid), show efficacy to alleviate P-ALI. Efficacy of drugs was judged by nitric oxide (eNO) and carbon dioxide (eCO2) in exhaled air and whether these non-invasive biomarkers are suitable to assess the degree of airway injury (chlorine) relative to alveolar injury (phosgene). P-ALI related analyses included lung function (enhanced pause, Penh), morbidity, increased lung weights, and protein in bronchial alveolar lavage fluid (BALF) one day postexposure. One of the pathophysiological hallmarks of P-ALI was indicated by increased Penh lasting for approximately 20 h postexposure. Following the administration of BUD, this increase could be suppressed; however, without significant improvement in survival and lung edema (increased lung weights and BALF-protein). Collectively, protocols shown to be efficacious for chlorine (Chen et al., 2013) were ineffective and even increased adversity in the P-ALI model. This outcome warrants further study to seek for early biomarkers suitable to differentiate chlorine- and phosgene-induced acute lung injury at yet asymptomatic stage. The patterns of eNO and eCO2 observed following exposure to chlorine and phosgene may be suitable to guide the specialized clinical interventions required for each type of ALI.

N-acetyl-L-cysteine protects against inhaled sulfur mustard poisoning in the large swine

CONTEXT

Sulfur mustard is a blister agent that can cause death by pulmonary damage. There is currently no effective treatment. N-acetyl-L-cysteine (NAC) has mucolytic and antioxidant actions and is an important pre-cursor of cellular glutathione synthesis. These actions may have potential to reduce mustard-induced lung injury.

OBJECTIVE

Evaluate the effect of nebulised NAC as a post-exposure treatment for inhaled sulfur mustard in a large animal model.

MATERIALS AND METHODS

Fourteen anesthetized, surgically prepared pigs were exposed to sulfur mustard vapor (100 μg.kg⁻¹), 10 min) and monitored, spontaneously breathing, to 12 h. Control animals had no further intervention (n = 6). Animals in the treatment group were administered multiple inhaled doses of NAC (1 ml of 200 mg.ml⁻¹ Mucomyst™ at + 30 min, 2, 4, 6, 8, and 10 h post-exposure, n = 8). Cardiovascular and respiratory parameters were recorded. Arterial blood was collected for blood gas analysis while blood and bronchoalveolar lavage fluid were collected for hematology and inflammatory cell analysis. Urine was collected to detect a sulfur mustard breakdown product. Lung tissue samples were taken for histopathological and post-experimental analyses.

RESULTS

Five of six sulfur mustard-exposed animals survived to 12 h. Arterial blood oxygenation (PaO₂) and saturation levels were significantly decreased at 12 h. Arterial blood carbon dioxide (PaCO₂) significantly increased, and arterial blood pH and bicarbonate (HCO₃⁻) significantly decreased at 12 h. Shunt fraction was significantly increased at 12 h. In the NAC-treated group all animals survived to 12 h (n = 8). There was significantly improved arterial blood oxygen saturation, HCO₃⁻ levels, and shunt fraction compared to those of the sulfur mustard controls. There were significantly fewer neutrophils and lower concentrations of protein in lavage compared to sulfur mustard controls.

DISCUSSION

NAC's mucolytic and antioxidant properties may be responsible for the beneficial effects seen, improving clinically relevant physiological indices affected by sulfur mustard exposure.

CONCLUSION

Beneficial effects of nebulized NAC were apparent following inhaled sulfur mustard exposure. Further therapeutic benefit may result from a combination therapy approach.

Diagnosis and management of environmental thoracic emergencies

Physiologic sequelae from increasing ambient pressure in underwater activities, decreasing ambient pressure while at altitude, or the consequences of drowning present a unique set of challenges to emergency physicians. In addition, several environmental toxins cause significant respiratory morbidity, whether they be pulmonary irritants, simple asphyxiants, or systemic toxins. It is important for emergency physicians to understand the pathophysiology of these illnesses as well as to apply this knowledge to the clinical arena either in the prehospital setting or in the emergency department. Current treatment paradigms and controversies within these regimens are discussed.

Results from the US industry-wide phosgene surveillance: the Diller Registry

OBJECTIVE

In 2004, The American Chemistry Council Phosgene Panel established a phosgene exposure registry among US phosgene producers with the primary purpose of monitoring health outcome information for workers with acute exposure.

METHODS

We examine symptoms among 338 workers with phosgene exposure. The phosgene exposures averaged 8.3 ppm-minutes ranging up to 159 ppm-minutes with most exposures below 10 ppm-minutes.

RESULTS

We found that the level of phosgene exposure in ppm-minutes was related to workers reporting mostly irritation symptoms of the nose, throat and eyes within 48 hours of exposure. However, we found no relationship between phosgene exposure and the presence of symptoms 30 days after exposure.

CONCLUSIONS

These findings lend credence to the theory that prolonged respiratory effects do not occur with doses less than 150 ppm-minutes.

Do corticosteroids have a role in preventing or reducing acute toxic lung injury caused by inhalation of chemical agents?

OBJECTIVE

To assess the evidence that treatment with corticosteroids improves the outcome in those exposed to lung-damaging agents.

METHODS

We searched Pubmed, Toxnet, Cochrane database, Google Scholar, and Embase from 1966 to January 2010 using the search terms "steroid", "corticosteroid", "lung injury", "lung damage", and "inhalation". These searches identified 287 papers of which 118 contained information on animal studies. However, most were reviews or case reports and only a few were controlled animal experiments of which 13 were considered relevant. ROLE OF CORTICOSTEROIDS:

ANIMAL STUDIES

Corticosteroids have no beneficial effect at the alveolar level on acute lung injury, which is caused by inhalation of poorly water-soluble compounds (e.g. nitrogen dioxide, ozone, phosgene) or following severe exposure to water-soluble compounds (e.g. chlorine, ammonia). In the recovery phase, corticosteroids may even be harmful, because corticosteroids hamper the division of type II alveolar cells and hamper the differentiation from type II into type I alveolar cells. The latter is important for the re-epithelialization of the alveolus and removal of excess of water in the alveolus. Furthermore, the quality of animal studies does not always allow extrapolation to human exposures. Differences between humans and animals in anatomy, pulmonary defense systems, breathing physiology, as well as the way the animals have been exposed, and the timing and route of corticosteroids in animal studies make predictions difficult. ROLE OF CORTICOSTEROIDS:

HUMAN STUDIES

An abundance of uncontrolled case reports and a few human crossover studies have evaluated the outcome of human volunteers exposed to various lung-damaging agents. Only a few reports contained systematic information on corticosteroid treatment. Data on the efficacy of corticosteroids after human exposure to lung-damaging agents are inconclusive. Often the number of patients involved is small or the severity of exposure is unclear or not well determined. These reports are therefore limited in their ability to establish a cause-effect relationship for the treatments involved. In some studies involving mild to moderate exposure to water-soluble agents (e.g. chlorine, ammonia), corticosteroid treatment was beneficial for some physiological parameters, such as airway resistance or arterial oxygen tension. However, severe lung injury and inflammation appear not to be improved by corticosteroid treatment. The optimal duration of treatment to obtain these beneficial effects has not been assessed adequately, but it only seems to be useful in the first hours after exposure. Generally, studies evaluating exposure to water-soluble compounds have too short a follow-up, which hampers the evaluation of the efficacy of corticosteroid treatment. The results of studies with longer follow-up suggest that the initial slight improvement in some variables is lost several hours after exposure.

CONCLUSIONS

Clinical data on the efficacy of corticosteroids after human exposure to lung-damaging agents are inconclusive as the number of well-structured controlled studies is small and the indications for administration of corticosteroids are unclear. There have been no human controlled studies of high-dose exposure to lung-damaging agents. Furthermore, treatment with corticosteroids is limited by the potential side effects, such as prolonged neuromuscular weakness, deregulation of glucose metabolism, superinfection, and sepsis, which could diminish the chances for recovery.

Management of phosgene-induced acute lung injury

CONTEXT

Phosgene is a substance of immense importance in the chemical industry. Because of its widespread industrial use, there is potential for small-scale exposures within the workplace, large-scale accidental release, or even deliberate release into a built-up area.

OBJECTIVE

This review aims to examine all published studies concerning potential treatments for phosgene-induced acute lung injury and incorporate them into up-to-date clinical guidance. In addition, it aims to contrast the approaches when dealing with small numbers of patients known to be exposed (possibly with dose information) with the presentation of a large and heterogeneous population of casualties following a significant industrial accident or deliberate release; no published guidelines have specifically addressed this second problem.

METHODS

PubMed and Embase were searched for all available years till April 2010 and 584 papers were identified and considered.

EXPERIMENTAL STUDIES

Because of the nature of the injury, there have been no human trials of patients exposed to phosgene. Multiple small and large animal studies have been performed to examine potential treatments of phosgene-induced acute lung injury, but many of these used isolated organ models, pretreatment regimens, or clinically improbable doses. Recent studies in large animals using both realistic time frames and dosing regimens have improved our knowledge, but clinical guidance remains based on incomplete data. Management of a small-scale, confirmed exposure. In the circumstance of a small-scale, confirmed industrial release where a few individuals are exposed and present rapidly, an intravenous bolus of high-dose corticosteroid (e.g., methylprednisolone 1 g) should be considered, although there are no experimental data to support this recommendation. The evidence is that there is no benefit from nebulized steroid even when administered 1 h after exposure, or methylprednisolone if administered intravenously ≥6 h after exposure. Consideration should also be given to administration of nebulized acetylcysteine 1-2 g, though there is no substantive evidence of benefit outside a small animal, isolated lung model and there is a possibility of adverse effects. If the oxygen saturation falls below 94%, patients should receive the lowest concentration of supplemental oxygen to maintain their SaO(2) in the normal range. Once patients require oxygen, nebulized β-agonists [e.g., salbutamol (albuterol) 5 mg by nebulizer every 4 h] may reduce lung inflammation if administered within 1 h of exposure. Elective intubation should be considered early using an ARDSnet protective ventilation strategy. Management of a large-scale, non-confirmed exposure. In the circumstances of a large-scale industrial or urban release, not all patients presenting will have been exposed and health services are likely to be highly stretched. In this situation, patients should not be treated immediately as there is no evidence that delaying therapy causes harm, rather they should be rested and observed with regular physical examination and measurement of peripheral oxygen saturations. Once a patient's oxygen saturation falls below 94%, treatment with the lowest concentration of oxygen required to maintain their oxygen saturations in the normal range should be started. Once oxygen has been started, nebulized β-agonists [e.g., salbutamol (albuterol) 5 mg by nebulizer every 4 h] may reduce lung inflammation if administered within 1 h of exposure, though delayed administration which is likely following a large-scale release has not been tested formally. There is no benefit from nebulized steroid even when administered 1 h after exposure, or high-dose corticosteroid if administered intravenously ≥6 h after exposure. Although there are no experimental data to support this recommendation, an intravenous bolus of high-dose corticosteroid (e.g., methylprednisolone 1 g) may be considered if presentation is <6 h and resources allow. Depending on the numbers of casualties presenting, invasive ventilation should be initiated either electively once symptoms present (especially where there is a short latent period, indicating likelihood of more significant injury), or delayed until required. Ventilation should be with high positive end expiratory pressure, ARDSnet recommended ventilation.

CONCLUSIONS

The mechanisms underlying the phosgene-induced acute lung injury are not well understood. Future experimental work should ensure that potential treatments are tested in a large animal model using realistic dosing regimens and clinically relevant timings, such as those that might be found in a mass casualty situation.

Accidental chlorine gas intoxication: evaluation of 39 patients

Background

Chlorine is a known pulmonary irritant gas that may cause acute damage in the respiratory system. In this paper, the socio-demographic and clinical characteristics of 39 accidentally exposed patients to chlorine gas are reported and different emergency treatment modalities are also discussed.

Methods

Two emergency departments applications were retrospectively analyzed for evaluation of accidental chlorine gas exposure for year 2007. Patients were classified into 3 groups according to severity of clinical and laboratory findings based on the literature and duration of land of stay in the emergency department. The first group was slightly exposed (discharged within 6 hours), second group moderately exposed (treated and observed for 24 hours), and third group was severely exposed (hospitalized). Most of the patients were initially treated with a combination of humidified oxygen, corticosteroids, and bronchodilators.

Results

The average age was 17.03 ± 16.01 years (95% CI). Seven (17.9%) of them were female and 29 (74.4%) were children. Twenty-four patients (61.5%) were included in the first, nine (23.1%) were in second and six (15.4%) were in the third group. The presenting symptoms were cough, nausea, and vomiting and conjunctiva hyperemia for the first group, first groups symptoms plus dyspnea for the second group. Second groups symptoms plus palpitation, weakness and chest tightness were for the third group. Cough and dyspnea were seen in 64.1% and 30.8% of the patients respectively. No patients died.

Conclusions

The authors recommend that non symptomatic or slightly exposed patients do not need any specific treatment or symptomatic treatment is sufficient.

Keywords

Accidental; Chlorine exposure; Chlorine gas; Chlorine intoxication; Emergency department