Occupational asthma (OA) could be divided into a nonimmunological, irritant-induced asthma and an immunological, allergy-induced asthma. In addition, allergy-induced asthma can be caused by two different groups of agents: high molecular weight proteins (>5,000 Da) or low molecular weight agents (<5,000 Da), generally chemicals like the isocyanates.
Isocyanates are very reactive chemicals characterized by one or more isocyanate groups (-N=C=O). The main reactions of this chemical group are addition reactions with ethanol, resulting in urethanes, with amines (resulting in urea derivates) and with water. Here, the product is carbamic acid which is not stable and reacts further to amines, releasing free carbon dioxide.

Diisocyanates and polyisocyanates are, together with the largely nontoxic polyol group, the basic building blocks of the polyurethane (PU) chemical industry, where they are used solely or in combination with solvents or additives in the production of adhesives, foams, elastomers, paintings, coatings and other materials.

The complex salts of platinum are one of the most potent respiratory sensitising agents having caused occupational asthma in more than 50% of exposed workers. Substitution of ammonium hexachlor platinate with platinum tetra amine dichloride in the manufacture of catalyst has controlled the problem in the catalyst industry. Ammonium hexachlorplatinate exposure still occurs in the refining process.

Rosin based solder flux fume is produced when soldering. This fume is a top cause of occupational asthma.

Bakeries, flour mills and kitchens where flour dust and additives in the flour are a common cause of occupational asthma.

Cadmium was not found to cause occupational asthma.

Pneumothorax refers to a condition in which air or gases accumulate inside the pleural space causing the lungs to collapse. Because the patient did not have a history of any previous pulmonary disease or trauma, this is a case of simple pneumothorax.

A history of measles, whooping cough, or other severe lung infections like tuberculosis (TB) and pneumonia can lead to airway damage and possibly bronchiectasis.

Post-primary pulmonary tuberculosis is a chronic disease commonly caused by either endogenous reactivation of a latent infection or exogenous re-infection by Mycobacterium tuberculosis.
Post-primary pulmonary tuberculosis (also called reactivation tuberculosis) develops in 5%-20% of patients infected with M. tuberculosis.

Found mainly in adults, this form of tuberculosis arises from the reactivation of bacilli that lay dormant within a fibrotic area of the lung. In adults, reinfection with a strain of mycobacterium that differs from that which caused the primary infection is also possible. Predisposing factors include immunosuppression, diabetes, malnutrition and alcoholism.

Infliximab is a monoclonal antibody against tumour necrosis factor ? (TNF-?). It is FDA approved for many autoimmune conditions, including rheumatoid arthritis and Crohn’s disease. One of the many known side effects of infliximab therapy is reactivation of latent tuberculosis (TB). Because of the resemblances in clinical and radiological features, tubercular lesions in the lung may mimic malignancy. TB accounts for 27% of all infections initially presumed to be lung cancer on imaging studies.

Infection with Klebsiella organisms occurs in the lungs, where they cause destructive changes. Necrosis, inflammation, and haemorrhage occur within lung tissue, sometimes producing a thick, bloody, mucoid sputum described as currant jelly sputum.
The illness typically affects middle-aged and older men with debilitating diseases such as alcoholism, diabetes, or chronic bronchopulmonary disease. An increased tendency exists toward abscess formation, cavitation, empyema, and pleural adhesions.

The normal partial pressure reference values are:
– PaO2 more than 80 mmHg (11 kPa)
– PaCO2 less than 45 mmHg (6.0 kPa).
This patient has an elevated PaCO2 (7.4kPa)
Hypoxemia (PaO2 <8kPa) with hypercapnia (PaCO2 >6.0kPa).
The pH is also lower than 7.35 at 7.3

Type 2 respiratory failure is caused by inadequate alveolar ventilation; both oxygen and carbon dioxide are affected. Defined as the build-up of carbon dioxide levels (PaCO2) that has been generated by the body but cannot be eliminated. The underlying causes include:
– Increased airways resistance (chronic obstructive pulmonary disease, asthma, suffocation)
– Reduced breathing effort (drug effects, brain stem lesion, extreme obesity)
– A decrease in the area of the lung available for gas exchange (such as in chronic bronchitis)
– Neuromuscular problems (Guillain-Barre syndrome, motor neuron disease)
– Deformed (kyphoscoliosis), rigid (ankylosing spondylitis), or flail chest.

Studies have shown that benefits of Long-tern oxygen therapy (LTOT) include improved exercise tolerance, with improved walking distance, and ability to perform daily activities, reduction of secondary polycythaemia, improved sleep quality and reduced sympathetic outflow, with increased sodium and water excretion, leading to improvement in renal function.

Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus called SARS-associated coronavirus (SARS-CoV). SARS was first reported in Asia in February 2003.
In general, SARS begins with a high fever (temperature greater than 38.0°C). Other symptoms may include headache, an overall feeling of discomfort, and body aches. Some people also have mild respiratory symptoms at the outset. About 10 to 20 percent of patients have diarrhoea. After 2 to 7 days, SARS patients may develop a dry cough. Most patients develop pneumonia. 

Serial Peak Expiratory Flow measurement at work and home is a feasible, sensitive, and specific test for the diagnosis of occupational asthma. For a diagnosis of occupational asthma, it is important to establish a relationship objectively between the workplace exposure and asthma symptoms and signs. Physiologically, this can be achieved by monitoring airflow limitation in relation to occupational exposure(s). If there is an effect of a specific workplace exposure, airflow limitation should be more prominent on work days compared with days away from work (or days away from the causative agent). Airflow limitation can be measured by spirometry, with peak expiratory flow (PEF) and/or forced expiratory volume in 1 s(FEV1) being the most useful for observing changes in airway calibre. Other tests mentioned are less reliable and would not help in establishing a satisfactory diagnosis of occupational asthma.

Allergic bronchopulmonary aspergillosis (ABPA) is a form of lung disease that occurs in some people who are allergic to Aspergillus. With ABPA, this allergic reaction causes the immune system to overreact to Aspergillus leading to lung inflammation. ABPA causes bronchospasm (tightening of airway muscles) and mucus build-up resulting in coughing, breathing difficulty and airway obstruction.

Blood tests are used to look for signs of an allergic reaction. This includes evaluating your immunoglobulin E (IgE) level. This level is increased with any type of allergy. Many people with asthma have higher than normal IgE levels. In ABPA however, the IgE level is extremely high (more than 1000 ng/ml or 417 IU/ml). In addition to total IgE, all patients with ABPA have high levels of IgE that is specific to Aspergillus. A blood test can be done to measure specific IgE to Aspergillus. A blood or skin test for IgE antibodies to Aspergillus can be done to see if a person is sensitized (allergic) to this fungus. If these skin tests are negative (i.e. does not show a skin reaction) to Aspergillus fumigatus, the person usually does not have ABPA.
Therefore, there should be no change in medication since this patient does not have ABPA.

Prolonged compression of the trachea by a large goitre will cause tracheomalacia following thyroidectomy.

The NICE 2017 guidelines state that in patients who are uncontrolled with a SABA (Salbutamol) and ICS (Inhaled corticosteroid e.g. Beclomethasone), a leukotriene receptor antagonist (LTRA) should be added.
If asthma is uncontrolled in adults (aged 17 and over) on a low dose of ICS as maintenance therapy, offer a leukotriene receptor antagonist (LTRA) in addition to the ICS and review the response to treatment in 4 to 8 weeks.

This recommendation is also stated in NICE 2019 guidelines.

Bronchiectasis is characterised by a blood stained productive cough with copious amount of sputum production, along with dyspnoea.

Ruptured diaphragm is a serious condition that is very difficult to diagnose and requires rapid intervention. The presence of bowel sounds on chest auscultation is highly suggestive of this.
Ruptured oesophagus is excluded by the absence of haematemesis and normal intestinal sounds.
Fractured ribs could be life threatening if associated with a tension pneumothorax which is excluded by a normal chest auscultation.
Flail chest is characterised by paradoxical breathing and respiratory failure.

In asthma, a reversible increase in residual volume (RV), functional residual capacity (FRC), and total lung capacity (TLC) may occur. There is a fall in FEV1, FVC and gas transfer.

In any patient with asthma, a decreasing PaO2 and an increasing PaCO2, even into the normal range, indicates severe airway obstruction that is leading to respiratory muscle fatigue and patient exhaustion.

Chest tightness and cough, which are the most common symptoms of asthma, are probably the result of inflammation, mucus plugs, oedema, or smooth muscle constriction in the small peripheral airways. Because major obstruction of the peripheral airways can occur without recognizable increases of airway resistance or FEV1, the physiologic alterations in acute exacerbations are generally subtle in the early stages. Poorly ventilated alveoli subtending obstructed bronchioles continue to be perfused, and as a consequence, the P(A-a)O2 increases and the PaO2 decreases. At this stage, ventilation is generally increased, with excessive elimination of carbon dioxide and respiratory alkalemia.

Pulmonary metastasis is seen in 20-54% of extrathoracic malignancies. The lungs are the second most frequent site of metastases from extrathoracic malignancies. Twenty percent of metastatic disease is isolated to the lungs. The development of pulmonary metastases in patients with known malignancies indicates disseminated disease and places the patient in stage IV in TNM (tumour, node, metastasis) staging systems.
Chest radiography (CXR) is the initial imaging modality used in the detection of suspected pulmonary metastasis in patients with known malignancies. Chest CT scanning without contrast is more sensitive than CXR.
Breast, colorectal, lung, kidney, head and neck, and uterus cancers are the most common primary tumours with lung metastasis at autopsy. Choriocarcinoma, osteosarcoma, testicular tumours, malignant melanoma, Ewing sarcoma, and thyroid cancer frequently metastasize to lung, but the frequency of these tumours is low.

Extrinsic allergic alveolitis (EAA) refers to a group of lung diseases that can develop after exposure to certain substances. The name describes the origin and the nature of these diseases:

‘extrinsic’ – caused by something originating outside the body
‘allergic’ – an abnormally increased (hypersensitive) body reaction to a common substance
‘alveolitis’ – inflammation in the small air sacs of the lungs (alveoli)

Symptoms can include: fever, cough, worsening breathlessness and weight loss. The diagnosis of the disease is based on a history of symptoms after exposure to the allergen and a range of clinical tests which usually includes: X-rays or CT scans, lung function and blood tests.

EAA is not a ‘new’ occupational respiratory disease and occupational causes include bacteria, fungi, animal proteins, plants and chemicals.

Examples of EAA include:

Bird fancier’s lung (BFL) is a type of hypersensitivity pneumonitis (HP). It is triggered by exposure to avian proteins present in the dry dust of the droppings and sometimes in the feathers of a variety of birds. The lungs become inflamed, with granuloma formation. Birds such as pigeons, parakeets, cockatiels, shell parakeets (budgerigars), parrots, turtle doves, turkeys and chickens have been implicated.

People who work with birds or own many birds are at risk. Bird hobbyists and pet store workers may also be at risk. This disease is an inflammation of the alveoli in the lungs caused by an immune response to inhaled allergens from birds. Initial symptoms include shortness of breath (dyspnoea), especially after sudden exertion or when exposed to temperature change, which can resemble asthma, hyperventilation syndrome or pulmonary embolism. Chills, fever, non-productive cough and chest discomfort may also occur.

A definitive diagnosis can be difficult without invasive testing, but extensive exposure to birds combined with reduced diffusing capacity are strongly suggestive of this disease. X-ray or CT scans will show physical changes to the lung structure (a ground glass appearance) as the disease progresses. Precise distribution and types of tissue damage differ among similar diseases, as does response to treatment with Prednisone.

Peak Expiratory Flow (PEF), also called Peak Expiratory Flow Rate (PEFR) is a person’s maximum speed of expiration, as measured with a peak flow meter. Measurement of PEFR requires some practise to correctly use a meter and the normal expected value depends on a patient’s gender, age and height.
It is classically reduced in obstructive lung disorders, such as Asthma, COPD or Cystic Fibrosis.

Extrinsic allergic alveolitis (EAA) refers to a group of lung diseases that can develop after exposure to certain substances. The name describes the origin and the nature of these diseases:

‘extrinsic’ – caused by something originating outside the body
‘allergic’ – an abnormally increased (hypersensitive) body reaction to a common substance
‘alveolitis’ – inflammation in the small air sacs of the lungs (alveoli)

Symptoms can include: fever, cough, worsening breathlessness and weight loss. The diagnosis of the disease is based on a history of symptoms after exposure to the allergen and a range of clinical tests which usually includes: X-rays or CT scans, lung function and blood tests.

EAA is not a ‘new’ occupational respiratory disease and occupational causes include bacteria, fungi, animal proteins, plants and chemicals.

Examples of EAA include:

Farmer’s lung
This is probably the most common occupational form of EAA and is the outcome of an allergic response to a group of microbes, which form mould on vegetable matter in storage. During the handling of mouldy straw, hay or grain, particularly in a confined space such as a poorly ventilated building, inhalation of spores and other antigenic material is very likely.

There also appears to be a clear relationship between water content of crops, heating (through mould production) and microbial growth, and this would apply to various crops and vegetable matter, with the spores produced likely to cause EAA.

Farmer’s lung can be prevented by drying crops adequately before storage and by ensuring good ventilation during storage. Respiratory protection should also be worn by farm workers when handling stored crops, particularly if they have been stored damp or are likely to be mouldy.

A single dose of intravenous magnesium sulphate is safe and may improve lung function and reduce intubation rates in patients with acute severe asthma. Intravenous magnesium sulphate may also reduce hospital admissions in adults with acute asthma who have had little or no response to standard treatment.

Consider giving a single dose of intravenous magnesium sulphate to patients with acute severe asthma (PEF <50% best or predicted) who have not had a good initial response to inhaled bronchodilator therapy. Magnesium sulphate (1.2-2 g IV infusion over 20 minutes) should only be used following consultation with senior medical staff.

Sarcoidosis is a chronic inflammatory condition that can affect any organ but mainly affects the lungs and lymph nodes. Cough can be due to any of the given conditions. Polyarthritis, erythema nodosum (erythematous painful subcutaneous nodules) and symmetric hilar and mediastinal lymphadenopathy are classical signs of sarcoidosis. This triad is known as Lofgren syndrome.

Pulmonary mycobacterium avium complex (MAC) infection in immunocompetent hosts generally manifests as cough, sputum production, weight loss, fever, lethargy, and night sweats. The onset of symptoms is insidious.
In patients who may have pulmonary infection with MAC, diagnostic testing includes acid-fast bacillus (AFB) staining and culture of sputum specimens.

The ATS/IDSA guidelines include clinical, radiographic, and bacteriologic criteria to establish a diagnosis of nontuberculous mycobacterial lung disease.

Clinical criteria are as follows:

Pulmonary signs and symptoms such as cough, fatigue, weight loss; less commonly, fever and weight loss; dyspnoea

Appropriate exclusion of other diseases (e.g., carcinoma, tuberculosis).

At least 3 sputum specimens, preferably early-morning samples taken on different days, should be collected for AFB staining and culture. Sputum AFB stains are positive for MAC in most patients with pulmonary MAC infection. Mycobacterial cultures grow MAC in about 1-2 weeks, depending on the culture technique and bacterial burden.

In adult practice, biochemical analysis of pleural fluid plays an important part in the management of pleural effusions. Protein levels or Light’s criteria differentiate exudates from transudates, while infection is indicated by pleural acidosis associated with raised LDH and low glucose levels. In terms of treatment, the pH may even guide the need for tube drainage, suggested by pH <7.2 in an infected effusion, although the absolute protein values are of no value in determining the likelihood of spontaneous resolution or chest drain requirements. pH is therefore the most important factor.

Assess the need for oxygen therapy in people with:
– very severe airflow obstruction (FEV1 below 30% predicted)
– cyanosis (blue tint to skin)
– polycythaemia
– peripheral oedema (swelling)
– a raised jugular venous pressure
– oxygen saturations of 92% or less breathing air.

Also consider assessment for people with severe airflow obstruction (FEV1 30-49% predicted).

Consider long-term oxygen therapy for people with COPD who do not smoke and who:
have a partial pressure of oxygen in arterial blood (PaO2) below 7.3 kPa when stable or have a PaO2 above 7.3 and below 8 kPa when stable, if they also have 1 or more of the following:
– secondary polycythaemia
– peripheral oedema
– pulmonary hypertension.

Malignant mesothelioma is a type of cancer that occurs in the thin layer of tissue that covers the majority of the internal organs (mesothelium).
Malignant Mesothelioma (MM) is a rare but rapidly fatal and aggressive tumour of the pleura and peritoneum. Aetiology of all forms of mesothelioma is strongly associated with industrial pollutants, of which asbestos is the principal carcinogen.

Thoracoscopically guided biopsy should be performed if mesothelioma is suggested; the results are diagnostic in 98% of cases. No specific treatment has been found to be of benefit, except radiotherapy, which reduces seeding and invasion through percutaneous biopsy sites.

Median survival for patients with malignant mesothelioma is 11 months. It is almost always fatal.

The clinical picture of the patient together with paraclinical investigations (spirometry) suggest COPD.

Non-invasive action via chest physiotherapy is helpful in the reduction or clearance of excessive secretions from airways.

Lofgren’s syndrome is characterised by a triad of erythema nodosum, arthritis and bilateral lymphadenopathy. It is a variant of sarcoidosis.