Suppurative Lung Diseases

Practice review flashcards covering etiology, pathogenesis, clinical features, diagnostic workup, and treatment of suppurative lung diseases including bronchiectasis, cystic fibrosis, lung abscess, and empyema with bronchopleural fistula.

How are suppurative lung diseases defined, and which three conditions are included in this group?

Suppurative lung diseases are characterized by cough and expectoration that is usually copious, fetid, and related to posture. They include: 1. Bronchiectasis, 2. Lung abscess, and 3. Empyema with bronchopleural fistula (where suppuration indicates the formation and discharge of pus).

What is the pathological definition of bronchiectasis?

Bronchiectasis is an abnormal permanent dilatation of the medium-sized cartilaginous bronchi, caused by variable destruction of the muscular and elastic components of the bronchial walls.

What clinical triad constitutes Kartagner’s syndrome?

1. Bronchiectasis
2. Sinusitis or absent frontal air sinuses
3. Dextrocardia or complete situs inversus

What triad of features defines Young’s syndrome?

1. Bronchiectasis
2. Sinusitis
3. Infertility (obstructive azospermia)

What are the luminal, mural, and extramural causes of localized bronchiectasis?

• Luminal: Endobronchial tumor, broncholithiasis, and foreign body (F.B)
• Mural: Atresia and stenosis
• Extramural: Extrinsic compression and traction bronchiectasis

Which specific disorders are associated with central versus upper lobe predominance in diffuse bronchiectasis?

• Central predominance: ABPA, Mounier Kuhn S, and William Campbell S
• Upper lobe predominance: Cystic fibrosis and sarcoidosis

What are the hallmark respiratory symptoms and physical signs of bronchiectasis?

Symptoms include chronic cough with large amounts of foul-smelling sputum (worse in the morning and on leaning forwards), dyspnea, haemoptysis, and wheezy chest. Physical signs include concomitant sinusitis, fever, weight loss, finger clubbing, and lower limb edema.

What are the key radiological findings on conventional chest X-ray and HRCT in bronchiectasis?

Chest X-ray may be normal or show a honeycomb or soap bubble appearance in cystic bronchiectasis. HRCT chest is the favored investigation for establishing the definitive diagnosis.

What are the specific indications and patient selection criteria for surgical treatment of bronchiectasis?

Surgery is indicated when disease is localized to one lung or part of a lung confirmed by HRCT in patients significantly disturbed by recurrent infective exacerbations or haemoptysis despite medical treatment over a period of at least $12\,\text{months}$. Patients must have good pulmonary function, no systemic causal factor, and be less than $40\,\text{years}$ of age.

What dose and schedule of human gamma globulin is indicated for bronchiectasis in patients with immunodeficiency syndromes?

Intramuscular (IM) administration of $25\,\text{mg/kg}$ at weekly or $2\text{-weekly}$ intervals.

What is the genetic inheritance pattern and defining features of cystic fibrosis?

An autosomal recessive heritable disorder causing widespread dysfunction of exocrine glands, presenting as chronic pulmonary disease (more in adolescents), pancreatic insufficiency (more in infants), malabsorption (thick sticky intestinal secretions; mucoviscidosis), and abnormally high electrolyte levels in sweat.

Based on this transport diagram, how does the mutant CFTR channel cause disease compared to the normal channel?

The normal CFTR channel moves chloride ions to the outside of the cell, whereas the mutant CFTR channel fails to transport chloride ions, resulting in sticky mucus building up on the outside of the cell.

How are chloride levels interpreted in the pilocarpine iontophoresis sweat test for cystic fibrosis?

• Positive result: $Cl^- > 60\,\text{mmol/L}$ (confirmed by $2$ separate tests)
• Borderline: $30 - 60\,\text{mmol/L}$ (must be repeated)
• Normal: $< 30\,\text{mmol/L}$

What newborn screening tests are used for the early detection of cystic fibrosis?

Immunoreactive trypsinogen measurement (IRT) from a dried blood sample on filter paper taken from the baby's foot or arm, followed by DNA mutation assessment to detect one or two mutations within $10 - 21\,\text{days}$.

How does cystic fibrosis affect the reproductive tract in males compared to females?

In males, the vas deferens is absent or atretic, resulting in azoospermia ($> 97\%$) and infertility. In females, increased viscosity and abnormal midcycle cervical mucus can sometimes cause infertility.

What is the definition of a lung abscess?

A localized area of destruction of lung parenchyma in which infection by pyogenic organisms results in tissue necrosis, suppuration, and cavity formation.

What is the sequence of pathogenesis in lung abscess formation that produces an air-fluid interface?

It starts as a small area of pneumonic consolidation with necrosis or microabscesses that coalesce into single or multiple areas of suppuration reaching $\ge 1\,\text{cm}$ in diameter; inflammation then erodes adjacent bronchi so pus is expectorated, allowing air to enter and create a fluid-air interface.

How does the cavity wall of an acute lung abscess differ from that of a chronic lung abscess on chest X-ray?

In an acute lung abscess, the cavity wall is thin with surrounding consolidation, whereas in a chronic lung abscess, the cavity wall is thick.

What diagnostic findings on thoracentesis indicate empyema?

Foul-smelling aspirate (suggesting anaerobic infection), positive Gram stain and culture, low pleural fluid $\text{pH} < 7.2$, and pleural fluid white cell count $\ge 15{,}000\,\text{mm}^{-3}$.

What bronchoscopic procedure is shown here to confirm a bronchopleural fistula?

The methylene blue test, where injection of methylene blue into the pleural space is detected emerging through the bronchial stump or expectorated in sputum.