Lambert-Eaton myasthenic syndrome (LEMS) is a rare presynaptic disorder of neuromuscular transmission in which release of acetylcholine (ACh) is impaired, causing a unique set of clinical characteristics, which include proximal muscle weakness, depressed tendon reflexes, post-tetanic potentiation, and autonomic changes.

In 40% of patients with LEMS, cancer is present when the weakness begins or is found later. This is usually a small cell lung cancer (SCLC). However, LEMS has also been associated with non-SCLC, lymphosarcoma, malignant thymoma, or carcinoma of the breast, stomach, colon, prostate, bladder, kidney, or gallbladder.

Long-term oxygen therapy (LTOT) ≥ 15 h/day improves survival in hypoxemic chronic obstructive pulmonary disease (COPD). It significantly helps in reducing pulmonary hypertension associated with COPD and treating underlying pathology of future heart failure. There is little to no benefit of oxygen therapy for less than 15 hours.

If a pleural effusion is present, a diagnostic thoracentesis may be performed and analysed for pH, lactate dehydrogenase, glucose levels, specific gravity, and cell count with differential. Pleural fluid may also be sent for Gram stain, culture, and sensitivity. Acid-fast bacillus testing may also be considered and the fluid may be sent for cytology if cancer is suspected.

The following findings are suggestive of an empyema or parapneumonic effusion that will likely need a chest tube or pigtail catheter for complete resolution:
-Grossly purulent pleural fluid
-pH level less than 7.2
-WBC count greater than 50,000 cells/µL (or polymorphonuclear leukocyte count of 1,000 IU/dL)
-Glucose level less than 60 mg/dL
-Lactate dehydrogenase level greater than 1,000 IU/mL
-Positive pleural fluid culture

The most often used golden criteria for empyema are pleural effusion with macroscopic presence of pus, a positive Gram stain or culture of pleural fluid, or a pleural fluid pH under 7.2 with normal peripheral blood ph.

Type I pneumocyte: The cell responsible for the gas (oxygen and carbon dioxide) exchange that takes place in the alveoli. It is a very thin cell stretched over a very large area. This type of cell is susceptible to a large number of toxic insults and cannot replicate itself.
Type II pneumocyte: The cell responsible for the production and secretion of surfactant (the molecule that reduces the surface tension of pulmonary fluids and contributes to the elastic properties of the lungs). The type 2 pneumocyte is a smaller cell that can replicate in the alveoli and will replicate to replace damaged type 1 pneumocytes. Alveolar macrophages are the primary phagocytes of the innate immune system, clearing the air spaces of infectious, toxic, or allergic particles that have evaded the mechanical defences of the respiratory tract, such as the nasal passages, the glottis, and the mucociliary transport system. The main role of goblet cells is to secrete mucus in order to protect the mucous membranes where they are found. Goblet cells accomplish this by secreting mucins, large glycoproteins formed mostly by carbohydrates.

Historically, high rates of maternal and fetal death have been reported for pregnant women with pulmonary hypertension (30–56% and 11–28%, respectively). The causes of poor maternal outcomes are varied and include risk of death from right heart failure and stroke from intracardiac shunting. Furthermore, there is a high peri-/post-partum risk due to haemodynamic stress, bleeding complications and the use of general anaesthesia, which can all lead to right heart failure.
The most common risk to the foetus is death, with premature birth and growth retardation being reported in successfully delivered children.
CXR is not contraindicated in pregnancy. D-dimers are not used as a diagnostic aid as they are almost always elevated in pregnancy. Nifedipine, although contraindicated in pregnant women may be used judiciously if the need arises.

The right and left lung anatomy are similar but asymmetrical. The right lung consists of three lobes: right upper lobe (RUL), right middle lobe (RML), and right lower lobe (RLL). The left lung consists of two lobes: right upper lobe (RUL) and right lower lobe (RLL). The right lobe is divided by an oblique and horizontal fissure, where the horizontal fissure divides the upper and middle lobe, and the oblique fissure divides the middle and lower lobes. In the left lobe there is only an oblique fissure that separates the upper and lower lobe.

The lobes further divide into segments which are associated with specific segmental bronchi. Segmental bronchi are the third-order branches off the second-order branches (lobar bronchi) that come off the main bronchus.

The right lung consists of ten segments. There are three segments in the RUL (apical, anterior and posterior), two in the RML (medial and lateral), and five in the RLL (superior, medial, anterior, lateral, and posterior). The oblique fissure separates the RUL from the RML, and the horizontal fissure separates the RLL from the RML and RUL.

There are eight to nine segments on the left depending on the division of the lobe. In general, there are four segments in the left upper lobe (anterior, apicoposterior, inferior and superior lingula) and four or five in the left lower lobe (lateral, anteromedial, superior and posterior). The medium sized airways offer the maximum airway resistance, not smaller ones.

Alveolar haemorrhage (AH) is a rare, but serious manifestation of SLE. It may occur early or late in disease evolution. Extrapulmonary disease may be minimal and may be masked in patients who are already receiving immunosuppressants for other symptoms of SLE.

DLCO or TLCO (diffusing capacity or transfer factor of the lung for carbon monoxide (CO)) is the extent to which oxygen passes from the air sacs of the lungs into the blood.
Factors that can increase the DLCO include polycythaemia, asthma (can also have normal DLCO) and increased pulmonary blood volume as occurs in exercise. Other factors are left to right intracardiac shunting, mild left heart failure (increased blood volume) and alveolar haemorrhage (increased blood available for which CO does not have to cross a barrier to enter).

Bronchial carcinoids are uncommon, slow growing, low-grade, malignant neoplasms, comprising 1-2% of all primary lung cancers.
It is believed to be derived from surface of bronchial glandular epithelium. Mostly located centrally, they produce symptoms and signs of bronchial obstruction such as localized wheeze, non resolving recurrent pneumonitis, cough, chest pain, and fever. Haemoptysis is present in approximately 50% of the cases due to their central origin and hypervascularity.
Central bronchial carcinoids are more common than the peripheral type and are seen as endobronchial nodules or hilar/perihilar mass closely related to the adjacent bronchus. Chest X-ray may not show the central lesion depending on how small it is.

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.

The phrenic nerve provides the primary motor supply to the diaphragm, the major respiratory muscle.
Phrenic nerve paralysis is a rare cause of exertional dyspnoea that should be included in the differential diagnosis. Fluoroscopy is considered the most reliable way to document diaphragmatic paralysis. During fluoroscopy a patient is asked to sniff and there is a paradoxical rise of the paralysed hemidiaphragm. This is to confirm that the cause is due to paralysis rather than unilateral weakness.

The tumour has only invaded the visceral pleura and measures 3cm in the greatest dimension. Hence it is designated at T2. Ipsilateral peribronchial and/or hilar lymph node involvement would make it N1. There is no distal metastasis so M would be 0.

The NICE 2019 guidelines states that in patients who are uncontrolled with a SABA (Salbutamol) and ICS (Beclomethasone), 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.

Cystic fibrosis (CF) is a multisystemic, autosomal recessive disorder that predominantly affects infants, children, and young adults. CF is the most common life-limiting genetic disorder in whites, with an incidence of 1 case per 3200-3300 new-borns in the United States.

People with CF can have a variety of symptoms, including:
Very salty-tasting skin
Persistent coughing, at times with phlegm
Frequent lung infections including pneumonia or bronchitis
Wheezing or shortness of breath
Poor growth or weight gain in spite of a good appetite
Frequent greasy, bulky stools or difficulty with bowel movements
Male infertility

Signs of bronchiectasis include the tubular shadows; tram tracks, or horizontally oriented bronchi; and the signet-ring sign, which is a vertically oriented bronchus with a luminal airway diameter that is 1.5 times the diameter of the adjacent pulmonary arterial branch.

Bronchiectasis is characterized by parallel, thick, line markings radiating from hila (line tracks) in cylindrical bronchiectasis. Ring shadows represent dilated thick-wall bronchi seen in longitudinal section or on-end or dilated bronchi in varicose bronchiectasis.

Pseudomonas aeruginosa is the key bacterial agent of cystic fibrosis (CF) lung infections, and the most important pathogen in progressive and severe CF lung disease. This opportunistic pathogen can grow and proliferate in patients, and exposure can occur in hospitals and other healthcare settings.

Haemophilus influenzae is regularly involved in chronic lung infections and acute exacerbations of CF patients

High-resolution CT (HRCT) scanning is more sensitive than standard chest radiography and is highly specific for diagnosing emphysema (outlined bullae are not always visible on a radiograph).

HRCT scanning may provide an adjunct means of diagnosing various forms of COPD (i.e., lower lobe disease may suggest AAT deficiency) and may help the clinician to determine whether surgical intervention would benefit the patient.

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.

Primary spontaneous pneumothorax is an abnormal accumulation of air in the space between the lungs and the chest cavity (called the pleural space) that can result in the partial or complete collapse of a lung. This type of pneumothorax is described as primary because it occurs in the absence of lung disease such as emphysema. Spontaneous means the pneumothorax was not caused by an injury such as a rib fracture. Primary spontaneous pneumothorax is likely due to the formation of small sacs of air (blebs) in lung tissue that rupture, causing air to leak into the pleural space. Air in the pleural space creates pressure on the lung and can lead to its collapse. A person with this condition may feel chest pain on the side of the collapsed lung and shortness of breath. Patients are typically aged 18-40 years, tall, thin, and, often, are smokers.

In small pneumothoraxes with minimal symptoms, no active treatment is required. These patients can be safely discharged with early outpatient review and should be given written advice to return if breathlessness worsens. Patients who have been discharged without intervention should be advised that air travel should be avoided until a radiograph has confirmed resolution of the pneumothorax.

Sarcoidosis is an inflammatory disease that affects one or more organs but most commonly affects the lungs and lymph glands. The inflammation may change the normal structure and possibly the function of the affected organ(s).
The presentation in sarcoidosis varies with the extent and severity of organ involvement, as follows:
Asymptomatic (incidentally detected on chest imaging): Approximately 5% of cases.
Systemic complaints (fever, anorexia): 45% of cases
Pulmonary complaints (dyspnoea on exertion, cough, chest pain, and haemoptysis [rare]): 50% of cases

Löfgren syndrome (fever, bilateral hilar lymphadenopathy, and polyarthralgias): Common in Scandinavian patients, but uncommon in African-American and Japanese patients.

Dermatologic manifestations may include the following:
– Erythema nodosum
– A lower-extremity panniculitis with painful, erythematous nodules (often with Löfgren syndrome)
– Lupus pernio (the most specific associated cutaneous lesion)
– Violaceous rash on the cheeks or nose (common)
– Maculopapular plaques (uncommon)

Staging of sarcoidosis is as follows:
Stage 0: Normal chest radiographic findings
Stage I: Bilateral hilar lymphadenopathy
Stage II: Bilateral hilar lymphadenopathy and infiltrates
Stage III: Infiltrates alone
Stage IV: Fibrosis

Nonsteroidal anti-inflammatory drugs (NSAIDs) are indicated for the treatment of arthralgias and other rheumatic complaints. Patients with stage I sarcoidosis often require only occasional treatment with NSAIDs.

Treatment in patients with pulmonary involvement is as follows:
Asymptomatic patients may not require treatment
In patients with minimal symptoms, serial re-evaluation is prudent
Treatment is indicated for patients with significant respiratory symptoms
Corticosteroids can produce small improvements in the functional vital capacity and in the radiographic appearance in patients with more severe stage II and III disease.

This patient has Stage 1 Sarcoidosis so observation is the most appropriate action.

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.

Asthma is a condition characterized by airway hyperresponsiveness, which results in reversible increases in bronchial smooth muscle tone, and variable amounts of inflammation of the bronchial mucosa.
During an acute asthma attack, the already inflamed airways narrow further due to bronchospasm, which leads to increased airway resistance. Because of the increased smooth muscle tone during an asthma attack, the airways also tend to close at abnormally high lung volumes, trapping air behind occluded or narrowed small airways. Thus the acute asthmatic will breathe at high lung volumes, his functional residual capacity will be elevated, and he will inspire close to total lung capacity. The accessory muscles of respiration are often used to maintain the lungs in a hyperinflated state.

During episodes of acute asthma, pulmonary function tests reveal an obstructive pattern. This includes a decrease in the rate of maximal expiratory air flow (a decrease in FEV1 and the FEV1/FVC ratio) due to the increased resistance, and a reduction in forced vital capacity (FVC) correlating with the level of hyperinflation of the lungs. Because these patients breathe at such high lung volumes (near the top of the pressure-volume curve, where lung compliance greatly decreases), they must exert significant effort to create an extremely negative pleural pressure, and consequently fatigue easily. Overinflation also reduces the curvature of the diaphragm, making it less efficient in generating further negative pleural pressure.

Churg-Strauss disease (CSD) is one of three important fibrinoid, necrotizing, inflammatory leukocytoclastic systemic small-vessel vasculitides that are associated with antineutrophil cytoplasm antibodies (ANCAs).
The first (prodromal) phase of Churg-Strauss disease (CSD) consists of asthma usually in association with other typical allergic features, which may include eosinophilia. During the second phase, the eosinophilia is characteristic (see below) and ANCAs with perinuclear staining pattern (pANCAs) are detected. The treatment would therefore be different from asthma. For most patients, especially those patients with evidence of active vasculitis, treatment with corticosteroids and immunosuppressive agents (cyclophosphamide) is considered first-line therapy

Idiopathic pulmonary fibrosis (IPF) is a condition in which the lungs become scarred and breathing becomes increasingly difficult.
The most common signs and symptoms of idiopathic pulmonary fibrosis are shortness of breath and a persistent dry, hacking cough. Many affected individuals also experience a loss of appetite and gradual weight loss.

The clinical findings of IPF are bibasilar reticular abnormalities, ground glass opacities, or diffuse nodular lesions on high-resolution computed tomography and abnormal pulmonary function studies that include evidence of restriction (reduced VC with an increase in FEV1/FVC ratio) and/or impaired gas exchange (increased P(A-a)O2 with rest or exercise or decreased diffusion capacity of the lung for carbon monoxide [DLCO]).

High Altitude Cerebral Oedema (HACE) is a severe and potentially fatal manifestation of high altitude illness and is often characterized by ataxia, fatigue, and altered mental status. HACE is often thought of as an extreme form/end-stage of Acute Mountain Sickness (AMS). Although HACE represents the least common form of altitude illness, it may progress rapidly to coma and death as a result of brain herniation within 24 hours, if not promptly diagnosed and treated.

HACE generally occurs after 2 days above 4000m but can occur at lower elevations (2500m) and with faster onset. Some, but not all, individuals will suffer from symptoms of AMS such as headache, insomnia, anorexia, nausea prior to transitioning to HACE. Some may also have concomitant High Altitude Pulmonary Oedema (HAPE). HACE in isolation is rare, but the absence of concomitant HAPE or symptoms of AMS prior to deterioration does not rule-out the presence of HACE.

Most cases develop as a progression of AMS and will include a history of recent ascent to altitude and prior complaints/findings of AMS including a headache, fatigue, nausea, insomnia, and/or light-headedness. Some may also have signs/symptoms of HAPE. Transition to HACE is heralded by signs of encephalopathy including ataxia (usually the earliest clinical finding) and altered mentation which may range from mild to severe. Other symptoms may include a more severe headache, difficulty speaking, lassitude, a decline in the level of consciousness, and/or focal neurological deficits or seizures.

The mainstay of treatment is the immediate descent of at least 1000m or until symptoms improve. If descent is not an option, one may use a portable hyperbaric chamber and/or supplemental oxygen to temporize illness, but this should never replace or delay evaluation/descent when possible. If available, dexamethasone 8mg for one dose, followed by 4mg every 6 hours should be given to adults via PO, IM, or IV routes.
Acetazolamide has proven to be beneficial in only a single clinical study. The suggested dosing regimen for Acetazolamide is 250 mg PO, given twice daily. Though effective in alleviating or temporizing symptoms, none of the adjunct treatment modalities are definitive or a replacement for an immediate descent.

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.

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.

Treatment of ABPA aims to control inflammation and prevent further injury to your lungs. ABPA is a hypersensitivity reaction that requires treatment with oral corticosteroids. Inhaled steroids are not effective. ABPA is usually treated with a combination of oral corticosteroids and anti-fungal medications. The corticosteroid is used to treat inflammation and blocks the allergic reaction. Examples
of corticosteroids include: prednisone, prednisolone or methylprednisolone. Inhaled corticosteroids alone – such as used for asthma treatment – are not effective in treating ABPA. Usually treatment with an oral corticosteroid is needed for months.

The second type of therapy used is an anti-fungal medication, like itraconazole and voriconazole. These medicines help kill Aspergillus so that it no longer colonizes the airway. Usually one of these drugs is given for at least 3 to 6 months. However, even this treatment is not curative and can have side effects.

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.

CURB Pneumonia Severity Score estimates the mortality of community-acquired pneumonia to help determine inpatient vs. outpatient treatment.
Select Criteria:
Confusion (abbreviated Mental Test Score <=8) (1 point)
Urea (BUN > 19 mg/dL or 7 mmol/L) (1 point)
Respiratory Rate > 30 per minute (1 point)
Blood Pressure: diastolic < 60 or systolic < 90 mmHg (1 point) The CURB-65 scores range from 0 to 5. Clinical management decisions can be made based on the score:
Score Risk Disposition
0 or 1 – 1.5% mortality – Outpatient care
2 – 9.2% mortality – Inpatient vs. observation admission
≥ 3 – 22% mortality – Inpatient admission with consideration for ICU admission with score of 4 or 5

Alpha-1 antitrypsin deficiency is an inherited disorder that may cause lung and liver disease. The signs and symptoms of the condition and the age at which they appear vary among individuals. This would be the most likely option as it is the only disease that can affect both liver and lung functions.
People with alpha-1 antitrypsin deficiency usually develop the first signs and symptoms of lung disease between ages 20 and 50. The earliest symptoms are shortness of breath following mild activity, reduced ability to exercise, and wheezing. Other signs and symptoms can include unintentional weight loss, recurring respiratory infections, fatigue, and rapid heartbeat upon standing. Affected individuals often develop emphysema. Characteristic features of emphysema include difficulty breathing, a hacking cough, and a barrel-shaped chest. Smoking or exposure to tobacco smoke accelerates the appearance of emphysema symptoms and damage to the lungs.
About 10 percent of infants with alpha-1 antitrypsin deficiency develop liver disease, which often causes yellowing of the skin and sclera (jaundice). Approximately 15 percent of adults with alpha-1 antitrypsin deficiency develop liver damage (cirrhosis) due to the formation of scar tissue in the liver. Signs of cirrhosis include a swollen abdomen, swollen feet or legs, and jaundice. Individuals with alpha-1 antitrypsin deficiency are also at risk of developing hepatocellular carcinoma.

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.

Small cell lung cancer (SCLC) is characterized by rapid growth and early dissemination. Prompt initiation of treatment is important.

Patients with clinical stage Ia (T1N0) after standard staging evaluation may be considered for surgical resection, but combined treatment with chemotherapy and radiation therapy is the standard of care. Radiation therapy is often added at the second cycle of chemotherapy.

Historically, patients undergoing surgery for small cell lung cancer (SCLC) had a dismal prognosis. However, more recent data suggest that patients with true stage I SCLC may benefit from surgical resection.

Common sites of hematogenous metastases include the brain, bones, liver, adrenal glands, and bone marrow. The symptoms depend upon the site of spread.

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–Barré syndrome, motor neuron disease)
– Deformed (kyphoscoliosis), rigid (ankylosing spondylitis), or flail chest.