Bronchiectasis following ammonia burns of the respiratory tract. A review of two cases

Ammonia exposure by intratracheal instillation causes severe and deteriorating lung injury and vascular effects in mice

OBJECTIVE

Ammonia (NH₃) is a corrosive alkaline gas that can cause life-threatening injuries by inhalation. The aim was to establish a disease model for NH₃-induced injuries similar to acute lung injury (ALI) described in exposed humans and investigate the progression of lung damage, respiratory dysfunction and evaluate biomarkers for ALI and inflammation over time.

METHODS

Female BALB/c mice were exposed to an NH₃ dose of 91.0 mg/kg·bw using intratracheal instillation and the pathological changes were followed for up to 7 days.

RESULTS

NH₃ instillation resulted in the loss of body weight along with a significant increase in pro-inflammatory mediators in both bronchoalveolar lavage fluid (e.g. IL-1β, IL-6, KC, MMP-9, SP-D) and blood (e.g. IL-6, Fibrinogen, PAI-1, PF4/CXCL4, SP-D), neutrophilic lung inflammation, alveolar damage, increased peripheral airway resistance and methacholine-induced airway hyperresponsiveness compared to controls at 20 h. On day 7 after exposure, deteriorating pathological changes such as increased macrophage lung infiltration, heart weights, lung hemorrhages and coagulation abnormalities (elevated plasma levels of PAI-1, fibrinogen, endothelin and thrombomodulin) were observed but no increase in lung collagen. Some of the analyzed blood biomarkers (e.g. RAGE, IL-1β) were unaffected despite severe ALI and may not be significant for NH₃-induced damages.

CONCLUSIONS

NH₃ induces severe acute lung injuries that deteriorate over time and biomarkers in lungs and blood that are similar to those found in humans. Therefore, this model has potential use for developing diagnostic tools for NH₃-induced ALI and for finding new therapeutic treatments, since no specific antidote has been identified yet.

High concentrations of ammonia induced cytotoxicity and bronchoconstriction in a precision-cut lung slices rat model

Exposure to high concentrations of ammonia (NH3) can cause life-threatening lung damages. The objective of this study was to establish a translational in vitro model for NH3-induced lung injury. Precision-cut lung slices (PCLS) from rats were exposed to NH3 and toxicological responses and cell viability were quantified by analysis of LDH, WST-1, inflammatory mediators (IL-1β, IL-6, CINC-1, MMP-9, RAGE and IL-18), and by microscopic evaluation of bronchoconstriction induced by electric-field-stimulation (EFS) or methacholine (MCh). Different treatment strategies were assessed to prevent or reverse the damages caused by NH3 using anti-inflammatory, anti-oxidant or neurologically active drugs. Exposure to NH3 caused a concentration-dependent increase in cytotoxicity (LDH/WST-1) and IL-1β release in PCLS medium. None of the treatments reduced cytotoxicity. Deposition of NH3 (24-59 mM) on untreated PCLS elicited an immediate concentration-dependent bronchoconstriction. Unlike MCh, the EFS method did not constrict the airways in PCLS at 5 h after NH3-exposure (47-59 mM). Atropine and TRP-channel antagonists blocked EFS-induced bronchoconstriction but these inhibitors could not block the immediate NH3-induced bronchoconstriction. In conclusion, NH3 exposure caused cytotoxic effects and lung damages in a concentration-dependent manner and this PCLS method offers a way to identify and test new concepts of medical treatments and biomarkers that may be of prognostic value.

Genetic determinants of ammonia-induced acute lung injury in mice

In this study, a genetically diverse panel of 43 mouse strains was exposed to ammonia, and genome-wide association mapping was performed employing a single-nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was used to help resolve the genetic determinants of ammonia-induced acute lung injury. The encoded proteins were prioritized based on molecular function, nonsynonymous SNP within a functional domain or SNP within the promoter region that altered expression. This integrative functional approach revealed 14 candidate genes that included Aatf, Avil, Cep162, Hrh4, Lama3, Plcb4, and Ube2cbp, which had significant SNP associations, and Aff1, Bcar3, Cntn4, Kcnq5, Prdm10, Ptcd3, and Snx19, which had suggestive SNP associations. Of these genes, Bcar3, Cep162, Hrh4, Kcnq5, and Lama3 are particularly noteworthy and had pathophysiological roles that could be associated with acute lung injury in several ways.

Comparisons of acute inflammatory responses of nose-only inhalation and intratracheal instillation of ammonia in rats

Objective: To establish a rat model with respiratory and pulmonary responses caused by inhalation exposure to non-lethal concentrations of ammonia (NH₃) that can be used for evaluation of new medical countermeasure strategies for NH₃-induced acute lung injury (ALI). This is of great value since no specific antidotes of NH₃-induced injuries exist and medical management relies on supportive and symptomatically relieving efforts. Methods: Female Sprague-Dawley rats (8-9 weeks old, 213g ± 2g) were exposed to NH₃ using two different exposure regimens; nose-only inhalation or intratracheal instillation. The experiment was terminated 5 h, 24 h, 14 and 28 days post-exposure. Results: Nose-only inhalation of NH₃ (9000-15 000 ppm) resulted in increased salivation and labored breathing directly post-exposure. Exposure did not increase inflammatory cells in bronchoalveolar lavage fluid but exposure to 12 000 ppm NH₃ during 15 min reduced body weight and induced coagulation abnormalities by increasing serum fibrinogen levels. All animals were relatively recovered by 24 h. Intratracheal instillation of NH₃ (1%) caused early symptoms of ALI including airway hyperresponsiveness, neutrophilic lung inflammation and altered levels of coagulation factors (increased fibrinogen and PAI-1) and early biomarkers of ALI (IL-18, MMP-9, TGFβ) which was followed by increased deposition of newly produced collagen 14 days later. Histopathology analysis at 5 h revealed epithelial desquamation and that most lesions were healed after 14 days. Conclusions: This study demonstrates that intratracheal instillation can reproduce several early hallmarks of ALI. Our findings therefore support that the intratracheal instillation exposure regimen can be used for new medical countermeasure strategies for NH₃-induced ALI.

The Role of the Immune Response in the Pathogenesis of Bronchiectasis

Bronchiectasis is a prevalent respiratory condition characterised by permanent and abnormal dilation of the lung airways (bronchi). There are a large variety of causative factors that have been identified for bronchiectasis; all of these compromise the function of the immune response to fight infection. A triggering factor may lead to the establishment of chronic infection in the lower respiratory tract. The bacteria responsible for the lower respiratory tract infection are usually found as commensals in the upper respiratory tract microbiome. The consequent inflammatory response to infection is largely responsible for the pathology of this condition. Both innate and adaptive immune responses are activated. The literature has highlighted the central role of neutrophils in the pathogenesis of bronchiectasis. Proteases produced in the lung by the inflammatory response damage the airways and lead to the pathological dilation that is the pathognomonic feature of bronchiectasis. The small airways demonstrate infiltration with lymphoid follicles that may contribute to localised small airway obstruction. Despite aggressive treatment, most patients will have persistent disease. Manipulating the immune response in bronchiectasis may potentially have therapeutic potential.

Occupational and environmental bronchiolar disorders

Occupational and environmental causes of bronchiolar disorders are recognized on the basis of case reports, case series, and, less commonly, epidemiologic investigations. Pathology may be limited to the bronchioles or also involve other components of the respiratory tract, including the alveoli. A range of clinical, functional, and radiographic findings, including symptomatic disease lacking abnormalities on noninvasive testing, poses a diagnostic challenge and highlights the value of surgical biopsy. Disease clusters in workplaces and communities have identified new etiologies, drawn attention to indolent disease that may otherwise have been categorized as idiopathic, and expanded the spectrum of histopathologic responses to an exposure. More sensitive noninvasive diagnostic tools, evidence-based therapies, and ongoing epidemiologic investigation of at-risk populations are needed to identify, treat, and prevent exposure-related bronchiolar disorders.

Effectiveness of common shelter-in-place techniques in reducing ammonia exposure following accidental release

Shelter-in-place strategies such as remaining indoors; breathing through a damp cloth; sealing cracks in windows and doors using towels, duct tape, or plastic sheeting; and running a shower are often recommended by emergency response officials to protect against accidental or intentional release of hazardous airborne chemicals and biologicals. Similar recommendations have been made to and used by community members exposed to anhydrous ammonia after catastrophic release of ammonia gas due to a derailment or other accidents. Such incidents have resulted in fatalities and serious injury to exposed individuals; however, other individuals within the same area have escaped injury and, in many cases, sustained no injuries as a result of sheltering-in-place. Although there are some studies that have evaluated the effectiveness of remaining in the home or breathing through a damp cloth to reduce exposure to various agents, there have been no studies that directly address the efficacy of running the shower in reducing exposure to ammonia gas. The present study was designed to simulate sheltering-in-place inside a typical bathroom with the shower running. The effectiveness of breathing through a damp cloth was also evaluated using a CPR mannequin placed inside a chamber built to represent a typical household bathroom. Ammonia gas at 300 or 1000 ppm was added to the chamber until the concentration peaked and stabilized, then the shower was turned on and the ammonia gas concentration was continuously monitored. In the mannequin studies, using a damp cloth reduced exposure to ammonia gas by 2- to 18-fold. Turning on the shower was even more effective at reducing ammonia levels. After 27 min, the ammonia concentration in the chamber was reduced to 2% of the initial concentration, even though gas was being continuously added to the chamber. These results indicate that use of shelter-in-place strategies substantially reduces ammonia exposure and that by combining shelter-in-place strategies, inhalation of ammonia gas can be reduced 100-fold even during prolonged exposure periods.

Aspiration, Bronchial Obstruction, Bronchiectasis, and Related Disorders

The conducting airways play a pivotal role in the spectrum of pulmonary pathology, not only as conduits for injurious agents to enter the lung, but also as an anatomic compartment that is affected by a diverse array of primary or secondary bronchocentric diseases. This chapter discusses aspiration and bronchial obstruction in detail, with emphasis on the aspiration of toxic, infective, or particulate matter. Lung abscess, a frequent complication of obstruction or aspiration, is also reviewed. Both aspiration and lung abscess are reconsidered within the context of pulmonary infectious disease mainly in Chapter 8 on bacterial infections, and to some extent in the chapters on mycobacterial (Chapter 9), fungal (Chapter 10), and parasitic diseases (Chapter 14).

Chronic Ammonia Inhalation and Interstitial Pulmonary Fibrosis: A Case Report and Review of the Literature

Ammonia is an irritant gas with a characteristic pungent odor, which is widely used in industry. Inasmuch as ammonia is highly soluble in water and, upon inhalation, is deposited in the upper airways, occupational exposures to ammonia have commonly been associated with sinusitis, upper airway irritation, and eye irritation. Acute exposures to high levels of ammonia have also been associated with diseases of the lower airways and interstitial lung. In this study, the authors report on a patient with long-term, repetitive occupational exposure to ammonia at levels at or above odor recognition who developed interstitial lung disease. The scientific literature on inhaled ammonia exposure is reviewed and discussed. The authors conclude that the taking of a careful occupational exposure history for patients presenting with shortness of breath associated with ammonia exposure may assist with an early diagnosis, thus allowing for treatment early in the disease process and prevention of further exposure.

Nonfatal work-related inhalations: surveillance data from hospital emergency departments, 1995-1996

BACKGROUND

Data from a stratified sample of hospital emergency rooms in the USA were used to describe nonfatal work-related inhalation injuries and illnesses during July 1995 to July 1996.

METHODS

Information was abstracted from emergency room records by the Consumer Product Safety Commission (CPSC) as part of the National Electronic Injury Surveillance System (NEISS) for all work-related injuries and illnesses regardless of product involvement.

RESULTS

There were an estimated 44,423 occupational inhalation cases nationwide, with an annual rate of 3.6 cases/10(4) workers/year. The rate for men (4.4 cases/10(4)) was greater than that observed for women (2.6 cases/10(4)), and the rates tended to decline with increasing age. An estimated 4.6% of the cases were hospitalized for further treatment. The highest rate by industry was 16.4 cases/10(4) for public administration (which included fire and police departments). Among non-firefighters, there were an estimated 6,470 cases nationwide in which respiratory symptoms or conditions were noted, which yielded an annual rate of 0.5 cases/10(4) (95% CI 0.3, 0.7). Chlorine compounds were a common agent for the cases with adverse respiratory outcomes.

CONCLUSIONS

The NEISS data provide an efficient method to learn about the national frequency of work-related inhalation injuries and illnesses. The National Institute for Occupational Safety and Health (NIOSH) is exploring two ways to use these data: first, to routinely review the reports to conduct surveillance for work-related inhalation cases; and second, to consider working with CPSC to conduct follow-back interviews of selected cases in order to learn more about the circumstances of the exposure, prior training of the case, and outcome of the exposure. Am. J. Ind. Med. 38:140-148, 2000. Published 2000 Wiley-Liss, Inc.

Frequency dependence of compliance in the evaluation of patients with unexplained respiratory symptoms

Frequency dependence of compliance (FDC) reflects non-homogeneous ventilatory distribution and, in the presence of a normal measured airway resistance, suggests peripheral airways dysfunction. This study evaluated peripheral airway function and bronchial reactivity in irritant exposed or non-exposed individuals with normal routine pulmonary function tests (PFTs) who had persistent unexplained lower respiratory symptoms. Twenty-two patients were identified with persistent respiratory symptoms and with normal chest X-ray and PFTs. Twenty were non-smokers; two had stopped smoking more than 10 years before evaluation. Twelve patients had been exposed to irritants in their workplaces or at home. Non-specific bronchial hyper-reactivity (nsBHR) and FDC, pre- and post-bronchodilator, were measured in all patients. Studies were repeated in 6/12 irritant-exposed subjects after exposure removal and inhaled corticosteroid treatment. Whereas 12/22 patients had nsBHR, all 22 subjects demonstrated FDC [dynamic lung compliance/static lung compliance Cdyn,1 / Cst,1 at respiratory frequency 60 min(-1) (f60), mean 46%, range 27-67%]. After bronchodilator administration, a 15% improvement Cdyn,1 was observed most consistently at f60 (mean% improvement 26%, 95% CI 14-38%) and in subjects without nsBHR. However, Cdyn,1 at f60 did not return to normal after inhaled bronchodilator. Irritant-exposed and unexposed individuals appeared similar in results of testing for FDC and nsBHR. FDC and its response to bronchodilators provide objective physiological measures of an airway abnormality which may provide a basis for clinical symptoms in patients with normal routine pulmonary function studies. The presence of persistently abnormal FDC after bronchodilator (BD) and on follow up studies may reflect chronic inflammatory and/or structural changes in the airways in addition to bronchoconstriction.

Asthma and chemical bronchitis in vanadium plant workers

BACKGROUND

Whether vanadium induces bronchial hyperresponsiveness and asthma in previously normal subjects is unresolved: the two reported series addressing this question both have shortcomings.

OBJECTIVE

To determine the cause of cough and breathlessness in vanadium plant workers after variable periods of exposure.

DESIGN

Case series of employees presenting with persistent symptoms over a 24-month study period.

PATIENTS AND METHODS

Forty of an estimated 1,440 patients were investigated by 1) blood count and serum IgE, 2) intracutaneous allergen skin tests, 3) spirometry, and 4) bronchoprovocation by histamine inhalation or exercise challenge. Exposure was assessed by measurement of 1) ambient V2O5, NH3 and SO2 over 7 days during the 24-month study period, 2) urine vanadium concentration at time of first presentation.

RESULTS

Twelve of 40 subjects had bronchial hyperreactivity (BHR), and these were compared to 12 age-matched companion subjects whose BHR was normal. In 10, BHR was diagnosed by histamine inhalation (PC20 0.25-1.82 mg/ml, nl > 8.0 mg/ml), and in six of these the abnormality was severe (PC20 < 0.5 mg/ml). A further two had BHR by exercise challenge (FEV1, 600 ml/30% and 770 ml/18% pre/post exercise). After removal from exposure, 9 of the 12 subjects returned for follow-up 5 to 23 months later. BHR was worse in one, still present although less severe in five, and was no longer found in one subject. Baseline spirometry measurements were normal in seven subjects and only mildly impaired in the remaining five of the 12 subjects with BHR.

CONCLUSION

This study provides strong supporting evidence that inhaled V2O5 induces BHR and asthma in subjects previously free of lung disease; the abnormality may persist for up to 23 months following exposure; routine spirometry will not detect affected subjects.

A placebo-controlled experimental study of steroid inhalation therapy in ammonia-induced lung injury

BACKGROUND

The use of corticosteroids in toxic lung injury caused by exposure to an irritating gas such as ammonia has not been adequately studied.

OBJECTIVE

To evaluate the effects of budesonide inhalation in a rabbit model of toxic lung injury induced by ammonia.

DESIGN

Randomized, blind placebo-controlled laboratory investigation employing 16 New Zealand White rabbits. Lung injury was induced by inhalation of a defined amount of aerosolized ammonia. Thirty minutes later, the rabbits were randomized to receive either inhalation therapy with 0.5 mg budesonide or placebo. After another 2 hours, a second treatment inhalation, identical to the first one, was administered.

RESULTS

Airway pressures, hemodynamics, and gas exchange were measured at baseline, 5, and 15 minutes after ammonia administration and every 30 minutes during a 6-hour period after the first blind inhalation of corticosteroids or placebo. The ammonia inhalation resulted in an acute severe lung injury, detected after 15 minutes as a decrease in Pao2 from 23.3 (+/- 3.6) to 11.0 (+/- 3.6) kPa (p < 0.005) and an increase in peak airway pressure from 13 (+/- 2) to 17 (+/- 2) cm H2O (p < 0.005). During the 6-hour observation period, the blood gas parameters improved gradually in all rabbits. In comparison with placebo, budesonide did not result in improved gas exchange or reduced airway pressure levels during the observation period.

CONCLUSION

In this animal model corticosteroid inhalation therapy had no effect on ammonia-induced lung injury.

Occupationally induced airways obstruction

The studies reviewed in this article indicate the association of occupational exposure to a variety of organic and inorganic dusts and various gases and fumes with chronic bronchitis and decrements of FEV1. Usually an obstructive pattern was noted, although in some occupations a similar decrement in FVC was noted. The effect of smoking on chronic bronchitis, respiratory symptoms, and FEV1 was usually additive, although workers exposed to cotton dust in one study demonstrated an interaction between exposure and smoking, as did a study of a general population sample. In coal workers, exposure to dust in younger workers resulted in a greater decline in lung function than if the exposure occurred in older workers. Studies in coal miners and grain workers further suggest that occupational standards in effect are not sufficient to protect the working population from adverse effects. The magnitude of the effect of occupation on decrement in FEV1 is usually less than cigarette smoking. Studies in coal miners indicate, however, that a minority of workers could be more severely affected by exposure. When considered together with cigarette smoking, additional decrements in lung function because of occupational exposure could contribute to disability. Additional study is needed for better understanding of exposure-response relationships, host factors, potential interaction with cigarette smoking, and pathophysiology of the development of occupationally induced airway disease.

Human health effects of agrichemical use

The use of pesticides and nitrogen fertilizers in agriculture has grown dramatically over the past 30 years. Currently, approximately 600 active pesticide ingredients are used, but adequate toxicologic data are available for only approximately 100 of these. Environmental exposure of humans to agrichemicals is common and results in both acute and chronic health effects, including acute and chronic neurotoxicity (insecticides, fungicides, fumigants), lung damage (paraquat), chemical burns (anhydrous ammonia), and infant methemoglobinemia (nitrate in groundwater). A variety of cancers also have been linked to exposure to various pesticides, particularly hematopoietic cancers. Immunologic abnormalities and adverse reproductive and developmental effects due to pesticides also have been reported. The health effects associated with pesticides do not appear to be restricted to only a few chemical classes. Therefore, enhanced efforts are needed to control or eliminate human exposures wherever possible. Research also is needed to better characterize and quantitate the adverse effects of agrichemicals on human health.

Acute and long term respiratory damage following inhalation of ammonia

A lifelong non-smoker who was the victim of a massive accidental exposure to anhydrous ammonia gas was followed up for 10 years. In the acute phase the patient presented with severe tracheobronchitis and respiratory failure, caused by very severe burns of the respiratory mucosa. After some improvement he was left with severe and fixed airways obstruction. Isotope studies of mucociliary clearance, computed tomography, and bronchography showed mild bronchiectasis. It is concluded that acute exposure to high concentrations of ammonia may lead to acute respiratory injury but also to long term impairment of respiratory function.

Expandable metal stents for tracheal obstruction: permanent or temporary? A cautionary tale

An expandable metal stent inserted via a long term tracheostomy successfully relieved life threatening respiratory obstruction due to benign tracheal stenosis. Later the patient's tracheostomy suction catheter became stuck on the stent and dislodged it. The stent was removed electively, without damaging the trachea, with a rigid biopsy forceps.

A longitudinal study of pulmonary function in fire fighters

Pulmonary function changes among fire fighters were evaluated by re-examining 632 Baltimore city fire fighters six to ten years after a baseline examination. Spirometry was used to determine forced expiratory volume in 1 second (FEV1). Information about exposures was obtained by questionnaire and by combining data from fire department records regarding the number of fires fought by fire fighting units with individual work histories. Men who never wore a mask while extinguishing fires experienced a 1.7 times greater rate of FEV1 decline than mask wearers. Men with ammonia exposure experienced a rate of decline 1.7 times greater than non-exposed men. Neither length of time spent in exposed jobs nor number of responses were associated with the rate of decline. Active fire fighters experienced a rate of decline 2.5 times greater than those who had retired or resigned. Some effects differed between men who were able to perform repeatable pulmonary function tests and those who were not.

Occupational obstructive disorders: nonspecific airways obstruction and occupational asthma

Airways obstruction as a result of occupational exposure may be divided into two categories on the basis of whether or not occupational asthma is present. The first category, nonspecific airways obstruction, takes place in the absence of occupational asthma, and demonstrates only modest changes in airways responsiveness. The second category, occupational asthma, usually has a causal relationship to exposure, and demonstrates marked changes in airways responsiveness. These distinctions are of use in diagnosis, treatment, and disability assessment.

Toxic pneumonitis from mixing household cleaners

In the past year we have seen three cases of life-threatening toxic pneumonitis caused by exposure to mixtures of household ammonia and bleach. This particular mixture forms intermediary chloramine compounds that cause toxic pneumonitis. Each patient had a prolonged hospitalization and was left with symptomatic residual roentgenographic changes. Exposure to mixtures of household ammonia and bleach may be a frequent cause of acute pneumonitis that is not well recognized.

Inhalation of ammonia vapour. A report on the management of eight patients during the acute stages

Eight men were admitted to hospital following exposure to gaseous ammonia at a local factory. They were divided into three groups, according to their clinical condition. The clinical findings, chest radiographs and treatment are discussed. One case was very severely injured. His management is discussed in detail. He required mechanical ventilation, positive end expiratory pressure and tracheostomy. The toxic effects of ammonia gas are discussed. A review of the literature is included. It was concluded that ammonia is an extremely irritant gas, capable of producing severe damage to all levels of the respiratory tract which may result in clinical impairment of respiratory function, ranging from mild to fatal. Prolonged respiratory support may be required. Superinfection may cause a late deterioration in those severely affected.

Fatal anhydrous ammonia inhalation

The morphologic and morphometric pulmonary alterations in a patient with anhydrous ammonia inhalation dying two months after exposure are described. Major pathologic findings included cylindrical bronchiectasis of the lower lobes, fibrous obliteration of small airways, and terminal nocardial pneumonia. Normal density of small airways was found, but the average diameter (0.50 mm.) was significantly less than that of controls (0.66 +/- 0.02). Fibrous obliteration of small airways may be characteristic of a late stage of bronchiolitis obliterans and is probably responsible for the chronic obstructive lung disease in the survivors of an episode of ammonia inhalation.