Exogenous lipid pneumonia is rare in the general population, but occupational accidents may not be uncommon in fire performers. Diagnosis is usually made on the basis of history of exposure to hydrocarbon fuels, symptoms, and radiological findings. The radiological findings are nonspecific, and the disease presents with variable patterns and distribution. For this reason, lipoid pneumonia may mimic many other diseases, and the diagnosis is often delayed.

Chest X-rays taken shortly after the accident may or may not be abnormal, but typically over time show infiltrates in the lower lobes of the lungs. High-resolution CT will frequently demonstrate abnormalities, including opacities, pleural effusion, consolidation, or pulmonary nodules. Histopathology of lung biopsy or bronchoalveolar lavage may indicate lipid-laden macrophages. Laboratory results may show highly elevated inflammatory markers.

Respiratory diseases may be investigated by performing one or more of the following tests

- Biopsy of the lung or pleura

- Blood test

- Bronchoscopy

- Chest x-ray

- Computed tomography scan, including high-resolution computed tomography

- Culture of microorganisms from secretions such as sputum

- Ultrasound scanning can be useful to detect fluid such as pleural effusion

- Pulmonary function test

- Ventilation—perfusion scan

Respiratory disease is a common and significant cause of illness and death around the world. In the US, approximately 1 billion "common colds" occur each year. A study found that in 2010, there were approximately 6.8 million emergency department visits for respiratory disorders in the U.S. for patients under the age of 18. In 2012, respiratory conditions were the most frequent reasons for hospital stays among children.

In the UK, approximately 1 in 7 individuals are affected by some form of chronic lung disease, most commonly chronic obstructive pulmonary disease, which includes asthma, chronic bronchitis and emphysema.

Respiratory diseases (including lung cancer) are responsible for over 10% of hospitalizations and over 16% of deaths in Canada.

In 2011, respiratory disease with ventilator support accounted for 93.3% of ICU utilization in the United States.

VALI is most common in patients receiving mechanical ventilation for acute lung injury or acute respiratory distress syndrome (ALI/ARDS).

Possible reasons for predisposition to VALI include:

- An injured lung may be at risk for further injury

- Cyclic atelectasis is particularly common in an injured lung

The course of treatment of fire breather's pneumonia remains controversial. Administration of bronchodilators, corticosteroids, and prophylactic antibiotics to prevent secondary infection, is a common course of treatment. Some studies suggest that steroids may improve outcomes in severely affected individuals, yet these data are only based on a limited number of patients. The use of gastric decontamination to prevent subsequent pulmonary injury from hydrocarbon ingestion is controversial. It may have potential benefit in large (> 30 cc), intentional ingestion of compounds with systemic toxicity.

Prognosis after peak symptoms is typically good, with most patients making a full recovery in weeks to months.

A CT scan of the lungs and histopathology along with a history of working in the flocking industry can diagnose flock worker's lung. A differential diagnosis may also include Sjögren's syndrome and lymphoid interstitial pneumonia. Flock worker's lung may be misdiagnosed as asthma or recurrent pneumonia. Though X-rays may be abnormal, CT scans are more useful as a diagnostic tool in flock worker's lung. Other diagnostic methods may include a transbronchial biopsy or wedge biopsy.

Flock worker's lung can be prevented with engineering controls that protect workers from inhaling flock. Engineering controls to prevent inhalation of flock can include using guillotine cutters rather than rotary cutters, and ensuring that blades are sharp, since dull blades shear off more respirable particles. Flocking plants have also implemented medical surveillance programs for workers to diagnose cases at an earlier stage. Another technique for preventing flock worker's lung is cleaning the workplace with alternatives to compressed air in order to avoid resuspending particulates in the air.

For some types of chILD and few forms adult ILD genetic causes have been identified. These may be identified by blood tests. For a limited number of cases this is a definite advantage, as a precise molecular diagnosis can be done; frequently then there is no need for a lung biopsy. Testing is available for

VALI does not need to be distinguished from progressive ALI/ARDS because management is the same in both. Additionally, definitive diagnosis of VALI may not be possible because of lack of sign or symptoms.

Investigation is tailored towards the symptoms and signs. A proper and detailed history looking for the occupational exposures, and for signs of conditions listed above is the first and probably the most important part of the workup in patients with interstitial lung disease. Pulmonary function tests usually show a restrictive defect with decreased diffusion capacity (DLCO).

A lung biopsy is required if the clinical history and imaging are not clearly suggestive of a specific diagnosis or malignancy cannot otherwise be ruled out. In cases where a lung biopsy is indicated, a trans-bronchial biopsy is usually unhelpful, and a surgical lung biopsy is often required.

The diagnosis is based upon a history of symptoms after exposure to the allergen and clinical tests. A physician may take blood tests, seeking signs of inflammation, a chest X-ray and lung function tests. The sufferer shows a restrictive loss of lung function.

Precipitating IgG antibodies against fungal or avian antigens can be detected in the laboratory using the traditional Ouchterlony immunodiffusion method wherein 'precipitin' lines form on agar plate. The ImmunoCAP technology has replaced this time consuming, labor-intensive method with their automated CAP assays and FEIA (Fluorescence enzyme immunoassay) that can detect IgG antibodies against Aspergillus fumigatus (Farmer's lung or for ABPA) or avian antigens (Bird Fancier's Lung).

Although overlapping in many cases, hypersensitivity pneumonitis may be distinguished from occupational asthma in that it is not restricted to only occupational exposure, and that asthma generally is classified as a type I hypersensitivity. Unlike asthma, hypersensitivity pneumonitis targets lung alveoli rather than bronchi.

General treatment principles are removal from exposure, protection of the airway (i.e., preemptive intubation), and treatment of hypoxemia. Concomitant airway injury with acute bronchospasm often warrants treatment with bronchodilators because of the airway obstruction.

A beneficial role for corticosteroids has not been established by controlled trials in humans. Despite the lack of controlled evidence of efficacy, anecdotal reports of benefits from systemic corticosteroid use continue to appear.

Prophylactic antibiotic drugs have not proved to be efficacious in toxic lung injury. Antibiotics should be reserved for those patients with clinical evidence of infection.

Lung biopsies can be diagnostic in cases of chronic hypersensitivity pneumonitis, or may help to suggest the diagnosis and trigger or intensify the search for an allergen. The main feature of chronic hypersensitivity pneumonitis on lung biopsies is expansion of the interstitium by lymphocytes accompanied by an occasional multinucleated giant cell or loose granuloma.

When fibrosis develops in chronic hypersensitivity pneumonitis, the differential diagnosis in lung biopsies includes the idiopathic interstitial pneumonias. This group of diseases includes usual interstitial pneumonia, non-specific interstitial pneumonia and cryptogenic organizing pneumonia, among others.

The prognosis of some idiopathic interstitial pneumonias, e.g. idiopathic usual interstitial pneumonia (i.e. idiopathic pulmonary fibrosis), are very poor and the treatments of little help. This contrasts the prognosis (and treatment) for hypersensitivity pneumonitis, which is generally fairly good if the allergen is identified and exposures to it significantly reduced or eliminated. Thus, a lung biopsy, in some cases, may make a decisive difference.

Multiple abnormal laboratory findings have been noted in indium lung. High levels of serum indium have been found in all cases of indium lung. Other abnormal laboratory values that have been found include elevated alanine aminotransferase, elevated aspartate aminotransferase, elevated C-reactive protein, elevated interstitial lung disease markers, and elevated GM-CSF autoantibodies.

Raised inflammatory markers (high ESR, CRP) are common but nonspecific. Examination of the coughed up mucus is important in any lung infection and often reveals mixed bacterial flora. Transtracheal or transbronchial (via bronchoscopy) aspirates can also be cultured. Fiber optic bronchoscopy is often performed to exclude obstructive lesion; it also helps in bronchial drainage of pus.

CT scanning and radiography can be used to aid in the diagnosis of indium lung. CT abnormalities include ground-glass opacities, interlobular septal thickening, honeycombing, and bronchiectasis.

According to a recent study, the main risk factors for RA-ILD are advancing age, male sex, greater RA disease activity, rheumatoid factor (RF) positivity, and elevated titers of anticitrullinated protein antibodies such as anticyclic citrullinated peptide. Cigarette smoking also appears to increase risk of RA-ILD, especially in patients with human leukocyte antigen DRB1.

A recently published retrospective study by a team from Beijing Chao-Yang Hospital in Beijing, China, supported three of the risk factors listed for RA-ILD and identified an additional risk factor. In that study of 550 RA patients, logistic regression analysis of data collected on the 237 (43%) with ILD revealed that age, smoking, RF positivity, and elevated lactate dehydrogenase closely correlated with ILD.

Recent studies have identified risk factors for disease progression and mortality. A retrospective study of 167 patients with RA-ILD determined that the usual interstitial pneumonia (UIP) pattern on high-resolution computed tomography (HRCT) was a risk factor for progression, as were severe disease upon diagnosis and rate of change in pulmonary function test results in the first 6 months after diagnosis.

A study of 59 RA-ILD patients found no median survival difference between those with the UIP pattern and those without it. But the UIP group had more deaths, hospital admissions, need for supplemental oxygen, and decline in lung function.

The exact cause of rheumatoid lung disease is unknown. However, associated factors could be due largely to smoking. Sometimes, the medicines used to treat rheumatoid arthritis, especially methotrexate, may result in lung disease.

Prevention's:

- Stop smoking: Chemicals found in cigarettes can irritate already delicate lung tissue, leading to further complications.

- Having regular checkups: The doctor could listen to lungs and monitor breathing, because lung problems that are detected early can be easier to treat.

Carbon monoxide (CO) is presumed to be a complication in smoke inhalation. The initial approach to presumed CO poisoning involves administering supplemental oxygen at a fraction of inspired oxygen (FiO2) of 100 percent and then the use of hyperbaric oxygen (HBO) therapy is evaluated by physicians.

The diagnosis can be confirmed by lung biopsy. A videoscopic assisted thoracoscopic wedge biopsy (VATS) under general anesthesia may be necessary to obtain enough tissue to make an accurate diagnosis. This kind of biopsy involves placement of several tubes through the chest wall, one of which is used to cut off a piece of lung to send for evaluation. The removed tissue is examined histopathologically by microscopy to confirm the presence and pattern of fibrosis as well as presence of other features that may indicate a specific cause e.g. specific types of mineral dust or possible response to therapy e.g. a pattern of so-called non-specific interstitial fibrosis.

Misdiagnosis is common because, while overall pulmonary fibrosis is not rare, each individual type of pulmonary fibrosis is uncommon and the evaluation of patients with these diseases is complex and requires a multidisciplinary approach. Terminology has been standardized but difficulties still exist in their application. Even experts may disagree with the classification of some cases.

On spirometry, as a restrictive lung disease, both the FEV1 (forced expiratory volume in 1 second) and FVC (forced vital capacity) are reduced so the FEV1/FVC ratio is normal or even increased in contrast to obstructive lung disease where this ratio is reduced. The values for residual volume and total lung capacity are generally decreased in restrictive lung disease.

Inhalation therapy with nebulized heparin and acetylcysteine is usually started and continued for five to seven days during the hospital stay.

The major criterion for diagnosis is typically a confirmed surgical biopsy. Minor diagnostic criteria have been proposed for DIPNECH.

- Clinical presentation: woman, between the age of 45 and 67 with cough and/or shortness of breath for 5–10 years

- Pulmonary function: increased residual volume, increased total lung capacity, fixed obstruction, low diffusing capacity of the lung for carbon monoxide that corrects with alveolar volume

- High-resolution CT scan: diffuse pulmonary nodules 4–10 mm, greater than 20 nodules, mosaic attenuation or air trapping in greater than 50% of the lung

- Transbronchial biopsy: proliferation of pulmonary neuroendocrine cells

- Serum markers: elevated serum chromogranin A levels

Treatment depends on the underlying cause. Treatments include iced saline, and topical vasoconstrictors such as adrenalin or vasopressin. Selective bronchial intubation can be used to collapse the lung that is bleeding. Also, endobronchial tamponade can be used. Laser photocoagulation can be used to stop bleeding during bronchoscopy. Angiography of bronchial arteries can be performed to locate the bleeding, and it can often be embolized. Surgical option is usually the last resort, and can involve, removal of a lung lobe or removal of the entire lung. Non–small-cell lung cancer can also be treated with erlotinib or gefitinib. Cough suppressants can increase the risk of choking.

"Fire-eater's lung" is an important variant of hydrocarbon pneumonitis, which typically involves adolescents or young adults who are exposed through mishap during flame-blowing performances using a variety of different flammable materials. The substances used overlap with some of the pediatric exposures (kerosene, gasoline) but can also include other hydrocarbons such as jet fuel and, in France, an aromatic hydrocarbon enriched petroleum-distillate called "kerdan". There has also been a case of citronella oil aspiration in a fire-eater. As with hydrocarbon pneumonitis in children, fire-eater's lung can also be complicated by pneumatocele. Although the term "acute lipoid pneumonia" has been used to refer to the "fire-eater's lung" syndrome, this is a misnomer.

The diagnosis is usually suspected following a CT scan. Typical features on CT include solid and sub-solid nodules, ground glass change and reticulation. There may be features of multi-system involvement such as adenopathy and splenomegaly.

The commonest abnormality on lung function testing is a decrease in gas transfer. Both obstructive and restrictive patterns on spirometry have been reported.

The differential diagnosis includes infection, other interstitial lung diseases and malignant disease including lymphoma. Exclusion of infection is therefore an important step in management, but confirmation of the diagnosis requires lung biopsy. In people who have lung disease prior to a diagnosis of CVID, the differential diagnosis includes sarcoidosis. Sarcoid is also characterised by granulomatous involvement of the lung and therefore patients being investigated for sarcoid should have serum immunoglobulins measured to exclude CVID.