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Types of Sputum

1. Mucoid

• Appearance: Clear, white, or grey; viscid and non-offensive
• Significance: Produced in excess mucus states without active infection
• Associated conditions: Chronic bronchitis (stable phase), asthma, bronchiectasis (between exacerbations)

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2. Purulent

• Appearance: Yellow or green, thick; due to neutrophils and cellular debris
• Significance: Reliable indicator of infection in the tracheobronchial tree or lungs
• Associated conditions: Acute bacterial pneumonia, bronchiectasis exacerbation, lung abscess

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3. Mucopurulent

• Appearance: Mixed - partially mucoid, partially purulent
• Significance: Transition between stable and infected states
• Associated conditions: Acute exacerbation of chronic bronchitis (COPD exacerbation - Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae are common pathogens), bronchiectasis

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4. Rust-Colored (Rusty)

• Appearance: Brown-orange ("rusty"); caused by even dispersion of blood in yellow, purulent sputum - as stated in Fishman's Pulmonary Diseases and Disorders
• Significance: Classic sign of lobar consolidation
• Associated conditions: Pneumococcal pneumonia (the hallmark) - "The classic presentation of pneumococcal pneumonia consists of... production of rusty or mucoid sputum" - Murray & Nadel's Textbook of Respiratory Medicine

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5. Currant Jelly

• Appearance: Red-black, thick, gelatinous, blood-mixed
• Significance: Necrotic lung tissue mixed with blood
• Associated conditions: Klebsiella pneumoniae pneumonia - "The classic description of sputum in Klebsiella pneumonia is a resemblance to currant jelly; it also contains blood, but it is bright red and more translucent and viscid than the sputum of pneumococcal pneumonia" - Fishman's Pulmonary Diseases and Disorders

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6. Foul-Smelling (Fetid) Purulent

• Appearance: Purulent, foul odor; may form layers on standing
• Significance: Anaerobic bacterial infection
• Associated conditions: Lung abscess, bronchiectasis (severe), anaerobic pneumonia (commonly streptococci) - "Purulent sputum with a foul odor usually indicates an anaerobic infection" - Fishman's Pulmonary Diseases and Disorders

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7. Pink Frothy

• Appearance: Blood-tinged foam, pink and frothy
• Significance: Alveolar flooding with blood-stained transudate
• Associated conditions: Acute pulmonary edema (left ventricular failure, mitral valve disease, aspiration chemical pneumonitis, negative-pressure pulmonary edema) - well-documented across multiple textbooks (Fishman's, Fuster & Hurst's The Heart, Barash's Clinical Anesthesia)

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8. Blood-Stained / Hemoptysis

• Appearance: Frankly blood-containing, ranging from streaks to massive
• Significance: Mucosal or vascular disruption in the airways/lungs
• Associated conditions:
  • Streaky blood - bronchitis, bronchogenic carcinoma (recurrent small hemoptysis common)
  • Massive hemoptysis - TB, bronchiectasis, pulmonary infarction, lung abscess

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9. Serous / Watery

• Appearance: Thin, watery, frothy but not pink
• Significance: Fluid transudation
• Associated conditions: Adenocarcinoma in situ (formerly BAC) - "large quantities of watery, mucoid sputum" - Fishman's; early pulmonary edema

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10. Hemosiderin-Laden ("Heart Failure" Sputum)

• Appearance: Brown-flecked; contains hemosiderin-laden macrophages
• Significance: Chronic pulmonary venous congestion
• Associated conditions: Chronic left heart failure, mitral stenosis

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11. Black / Dark

• Appearance: Black or dark grey
• Significance: Inhaled carbonaceous material
• Associated conditions: Coal workers' pneumoconiosis (anthracosis), heavy smokers

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12. Anchovy Sauce

• Appearance: Thick, dark-brown, resembling anchovy sauce
• Significance: Hepatic abscess contents entering the lung
• Associated conditions: Hepatic amoebiasis with pleuropulmonary extension (amoebic empyema/lung abscess)

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Quick Reference Table

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Bronchitis

A. Chronic Bronchitis

Definition

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Etiology / Pathogenesis

1. Mucus hypersecretion - the earliest feature; caused by enlargement of submucosal mucus-secreting glands in the trachea and bronchi, driven by mediators including histamine and IL-13. Goblet cells increase in small airways as well.
2. Acquired CFTR dysfunction - cigarette smoke leads to acquired CFTR dysfunction, causing secretion of abnormal, dehydrated mucus that worsens chronic bronchitis.
3. Inflammation - inhaled irritants cause neutrophil, lymphocyte, and macrophage infiltration. Unlike asthma, eosinophils are NOT seen.
4. Infection - does not initiate chronic bronchitis but maintains it and triggers acute exacerbations.

• Cigarette smoking (90% of cases)
• Air pollutants (sulfur dioxide, nitrogen dioxide)
• Grain dust, cotton dust, silica

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Morphology

• Hyperemic, swollen, edematous mucosal lining of large airways
• Mucinous or mucopurulent secretions covering the lumen
• Smaller bronchi and bronchioles filled with secretions

• Enlargement of mucus-secreting submucosal glands - assessed by the Reid Index (ratio of gland layer thickness to bronchial wall thickness between epithelium and cartilage). Normal = 0.4; elevated in chronic bronchitis, proportional to severity.
• Goblet cell hyperplasia in small airways
• Smooth muscle hypertrophy, peribronchial fibrosis
• Chronic inflammatory cells (lymphocytes, macrophages)
• Mucus plugging, inflammation, and fibrosis leading to bronchiolar narrowing
• In severe cases: bronchiolitis obliterans (complete obliteration of bronchiolar lumen by fibrosis)

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Clinical Features

• Persistent productive cough with mucoid sputum (early); becomes mucopurulent during exacerbations
• Progressive airflow obstruction (small airway disease)
• May develop chronic outflow obstruction with associated emphysema
• Advanced disease: hypoxemia, pulmonary hypertension, cor pulmonale
• Common exacerbation pathogens: Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pneumoniae

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B. Acute Bronchitis

• Acute self-limiting inflammation of the trachea and bronchi
• Mostly viral (rhinovirus, influenza, parainfluenza, RSV)
• Presents with cough, low-grade fever, mucoid or mucopurulent sputum
• Usually resolves within 2-3 weeks; antibiotics not routinely indicated

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Bronchiectasis

Definition

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Etiology / Causes

• Cystic fibrosis - most important; defective CFTR causes thick viscid secretions, impaired mucociliary clearance, chronic bacterial infection, and widespread bronchial wall destruction
• Primary ciliary dyskinesia (Kartagener syndrome) - autosomal recessive; dynein arm mutations impair cilia, preventing clearance; ~50% have situs inversus + bronchiectasis + sinusitis; males are infertile due to sperm dysmotility
• Immunodeficiency states - selective IgA deficiency, hypogammaglobulinemia
• Intralobar pulmonary sequestration

• Necrotizing bacterial pneumonia (postpneumonia bronchiectasis)
• Pertussis, measles, severe influenza, varicella pneumonia
• Tuberculosis (upper lobe predilection)

• Tumors, foreign body, impacted mucus - produce localized bronchiectasis distal to obstruction

• Allergic bronchopulmonary aspergillosis (ABPA) - Th2 response to Aspergillus fumigatus, high IgE, eosinophilic airway inflammation, mucus plugs
• Rheumatoid arthritis, SLE, inflammatory bowel disease
• Post-lung transplant (chronic rejection), post-HSCT (graft-vs-host disease)

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Pathogenesis - "Vicious Cycle"

1. Airway epithelial and ciliary dysfunction + mucus hypersecretion
2. Chronic infection induces further mucus hypersecretion
3. Inflammation causes permanent airway injury and dilation
4. Bronchiectatic airways have poor mucociliary clearance → perpetuates infection and inflammation

• Haemophilus influenzae (~50-55%)
• Pseudomonas aeruginosa (12-30%)
• Streptococcus pneumoniae (~12%)
• Nontuberculous mycobacteria

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Types (Morphologic Classification)

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Morphology

• Lower lobes bilaterally affected in most cases (except TB which affects upper lobes)
• Airways dilated up to 4x normal size; can be followed almost to the pleural surface (normally bronchioles are not visible within 2-3 cm of pleura)
• On cut surface: dilated bronchi appear cystic, filled with mucopurulent secretions

• Acute and chronic inflammatory exudate within bronchial/bronchiolar walls
• Desquamation of lining epithelium with extensive ulceration
• Squamous metaplasia of remaining epithelium (further impairs clearance)
• Necrosis may form abscess cavities
• Fibrosis of bronchial/bronchiolar walls in chronic cases → bronchiolar obliteration
• In ABPA: fungal hyphae visible on special stains within mucoid plugs

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Clinical Features

• Severe persistent cough with copious foul-smelling, sometimes bloody sputum
• Daily sputum volume 10 mL to >150 mL, correlating with disease extent
• Paroxysms of cough on waking - postural drainage of accumulated secretions
• Progressive dyspnea and orthopnea in severe cases
• Hemoptysis (may be massive - erosion of hypertrophied bronchial arteries)
• "Dry bronchiectasis" - nonproductive cough; upper lobe involvement (common in TB)
• Episodes precipitated by upper respiratory infections

• Cor pulmonale
• Brain abscesses
• Secondary amyloidosis

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Diagnosis

• HRCT chest - modality of choice; shows dilated thick-walled bronchi, "signet ring sign," "train tracks"
• CXR: hyperinflation, bronchiectatic cysts, dilated thick-walled bronchi
• Sputum culture and sensitivity
• Sputum AFB smear/culture (for nontuberculous mycobacteria)
• Spirometry - obstructive pattern

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Management (Schwartz's Principles of Surgery)

1. Airway clearance - chest physiotherapy (percussion, vibration, postural drainage)
2. Bronchodilators for reversible airflow limitation
3. Antibiotics for exacerbations - 2-3 weeks of broad-spectrum IV antibiotics (tailored to culture), followed by oral course
4. Macrolide antibiotics - decrease sputum production, inhibit cytokine release, inhibit neutrophil adhesion, disrupt Pseudomonas biofilm
5. Hypertonic saline (7%) - improves mucociliary clearance, reduces exacerbations, improves FEV₁ by 15%
6. Inhaled antibiotics (tobramycin, colistin) - improve bacterial clearance

• Resection of localized bronchiectatic segment/lobe for refractory symptoms
• Multifocal disease must be excluded before surgery
• Bronchial artery embolization for massive hemoptysis (preferred over surgery)
• Bilateral lung transplant for end-stage disease

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Quick Comparison

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Bleeding Diatheses

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Diagnostic Laboratory Tests (Overview)

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Classification of Bleeding Diatheses

I. Vascular / Connective Tissue Disorders

• Vitamin C deficiency (Scurvy) - defective collagen synthesis in vessel walls
• Amyloidosis affecting blood vessels
• Chronic glucocorticoid use - connective tissue atrophy
• Rare inherited connective tissue disorders (Ehlers-Danlos syndrome, Marfan syndrome)
• Infectious/hypersensitivity vasculitides - Henoch-Schonlein purpura (IgA vasculitis), meningococcemia (DIC/petechiae from endothelial damage)
• Senile purpura - atrophic connective tissue in elderly

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II. Platelet Disorders (Primary Hemostasis Defects)

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A. Thrombocytopenia (Quantitative Defects)

• Generalized bone marrow failure: aplastic anemia, marrow infiltration (leukemia, disseminated cancer)
• Selective impairment: drug-induced (alcohol, thiazides, cytotoxic drugs), infections (measles, HIV)
• Ineffective megakaryopoiesis: megaloblastic anemia, paroxysmal nocturnal hemoglobinuria (PNH)

• Immune Thrombocytopenic Purpura (ITP)
• Autoimmune: SLE
• Alloimmune: post-transfusion, neonatal
• Drug-associated: quinidine, heparin (HIT), sulfa compounds
• Infections: EBV, HIV, CMV

• DIC
• TTP (Thrombotic Thrombocytopenic Purpura)
• HUS (Hemolytic Uremic Syndrome)
• Microangiopathic hemolytic anemias

• Hypersplenism

• Multiple blood transfusions for massive blood loss

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Immune Thrombocytopenic Purpura (ITP) - Key Details

• Chronic ITP: Most common in women 20-40 years. Autoantibodies (IgG) against platelet membrane glycoproteins IIb/IIIa or Ib/IX - detected in ~80% of cases. Spleen is the major site of both antibody production and IgG-coated platelet destruction.
• Bone marrow: Increased megakaryocytes (compensatory).
• Features: Petechiae, easy bruising, epistaxis, gum bleeding, hemorrhage after minor trauma. Serious intracranial hemorrhage is rare.
• Treatment: Glucocorticoids, IV immunoglobulin. Splenectomy (normalizes platelet count in >2/3 of patients).
• Acute ITP (children): Post-viral, self-limited.

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Thrombotic Thrombocytopenic Purpura (TTP)

1. Thrombocytopenia
2. Microangiopathic hemolytic anemia (MAHA) - fragmented RBCs (schistocytes)
3. Renal failure
4. Fever
5. CNS involvement

• Acquired (autoantibodies to ADAMTS13)
• Inherited

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Hemolytic Uremic Syndrome (HUS)

• Features: Thrombocytopenia + MAHA + renal failure (predominant; less CNS involvement than TTP)
• Pathogenesis: Deficiencies of complement regulatory proteins OR exposure to endothelial-damaging agents (e.g., Shiga toxin from E. coli O157:H7) → platelet activation, aggregation, microvascular thrombosis.

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B. Qualitative Platelet Defects

• Acquired: Uremia (uremic toxins impair platelet function), aspirin (irreversibly inhibits COX-1, blocking thromboxane A2), myeloproliferative neoplasms
• Inherited: von Willebrand disease (see below), Glanzmann thrombasthenia (absent GpIIb/IIIa), Bernard-Soulier syndrome (absent GpIb)

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III. Coagulation Factor Disorders (Secondary Hemostasis Defects)

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A. von Willebrand Disease (vWD)

• Most common inherited bleeding disorder (~1% of US population)
• Inheritance: Autosomal dominant (most types)
• Mechanism: Mutations in vWF cause:
  1. Impaired platelet adhesion (vWF bridges platelet GpIb to subendothelial collagen)
  2. Secondary factor VIII deficiency (vWF normally stabilizes factor VIII in circulation)
• Presentation: Spontaneous bleeding from mucous membranes, excessive bleeding from wounds, menorrhagia. Resembles platelet disorder (mucosal bleeding, petechiae) because primary hemostasis is affected.
• Diagnosis: Ristocetin platelet agglutination test (ristocetin enhances vWF-GpIb binding, causing platelet agglutination - absent/reduced in vWD)

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B. Hemophilia A (Factor VIII Deficiency)

• Most common hereditary cause of serious bleeding
• X-linked recessive - primarily affects males
• ~30% caused by new mutations
• Pathogenesis: Reduced factor VIII activity → impaired intrinsic pathway → PTT prolonged, PT normal
• Severity:
  • Severe: factor VIII activity <1% of normal - spontaneous bleeds
  • Moderate/Mild: activity 1-30% - bleed with trauma/surgery
• Features:
  • Easy bruising, hemorrhage after trauma or surgery
  • Hemarthroses (recurrent joint bleeds leading to crippling deformities) - classic
  • Deep soft tissue hemorrhages
  • Petechiae absent (primary hemostasis intact)
• Diagnosis: Prolonged PTT, corrected by mixing with normal plasma. Specific factor VIII assay confirms.
• Treatment: Recombinant factor VIII infusion. ~15% of severe cases develop factor VIII inhibitor antibodies → treated with bispecific antibody (emicizumab, binds factor IX and X, bypassing factor VIII).

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C. Hemophilia B (Factor IX Deficiency - Christmas Disease)

• X-linked recessive, much less common than Hemophilia A
• Clinically indistinguishable from Hemophilia A
• PTT prolonged; diagnosis by specific factor IX assay
• Treated with recombinant factor IX

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D. Other Factor Deficiencies

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IV. Mixed / Combined Disorders

Disseminated Intravascular Coagulation (DIC)

• "Consumptive coagulopathy" - the most common cause of serious acquired bleeding
• Mechanism: Systemic activation of coagulation → widespread microvascular thrombi → consumption of platelets + coagulation factors → secondary fibrinolysis activation → paradoxical bleeding

• Triggered by: (1) release of tissue factor/thromboplastin into circulation, or (2) widespread endothelial damage
• In sepsis: endotoxins stimulate monocytes to express tissue factor and release IL-1/TNF, which upregulate tissue factor on endothelial cells and downregulate thrombomodulin (anti-coagulant)

• Microthrombi in kidneys (most common: fibrin thrombi in glomeruli → renal cortical necrosis), adrenals, brain, heart
• Bilateral adrenal hemorrhagic necrosis (Waterhouse-Friderichsen syndrome in meningococcemia)
• Petechiae and ecchymoses on skin, serosal linings, epicardium, endocardium, lungs, urinary tract

• Acute DIC (e.g., obstetric): dominated by bleeding - petechiae, ecchymoses, gut/urinary tract hemorrhage
• Chronic DIC (e.g., adenocarcinoma): dominated by thrombosis - signs of ischemia/organ damage

• Thrombocytopenia
• PT and PTT both prolonged
• Low fibrinogen
• Elevated fibrin split products (D-dimer) - the hallmark
• Microangiopathic hemolytic anemia (schistocytes on smear)

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Summary Table

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Causes of Pneumothorax

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Classification

Pneumothorax
├── Spontaneous
│   ├── Primary (PSP) - no underlying lung disease
│   └── Secondary (SSP) - underlying lung disease
├── Traumatic
│   ├── Non-iatrogenic (blunt/penetrating)
│   └── Iatrogenic (procedural)
└── Special types
    ├── Tension pneumothorax
    └── Catamenial pneumothorax

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1. PRIMARY SPONTANEOUS PNEUMOTHORAX (PSP)

Mechanism

• Rupture of subpleural apical blebs or bullae (emphysema-like changes found at lung apices)
• Patients with PSP have microscopic structural abnormalities despite an apparently "normal" chest radiograph: distal airways inflammation, "pleural porosity," and emphysema-like changes - Murray & Nadel's Textbook of Respiratory Medicine
• High mechanical stress at lung apices (due to greater negative pleural pressure) promotes bleb formation

Risk Factors

• Tall, thin, young males (ectomorphic body habitus) - 3x more common in men than women; bimodal age distribution with first peak at 15-34 years
• Smoking - significantly increases risk; also increases recurrence risk
• Marfan syndrome - connective tissue laxity predisposes to bleb formation
• Birt-Hogg-Dube syndrome - rare autosomal dominant condition with pulmonary cysts
• Mitral valve prolapse
• Changes in ambient atmospheric pressure
• Genetic predisposition (rare)

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2. SECONDARY SPONTANEOUS PNEUMOTHORAX (SSP)

Causes (Box 63.1 - Rosen's Emergency Medicine):

Airway Disease

• COPD/Emphysema - most common cause in the United States; rupture of emphysematous bullae
• Asthma - air trapping leading to alveolar rupture
• Cystic fibrosis - diffuse bronchiectasis, mucus plugging, and cyst formation

Infections

• Necrotizing bacterial pneumonia / Lung abscess - cavity rupture into pleural space
• Pneumocystis jirovecii pneumonia (PCP) - subpleural cysts and necrosis; notoriously difficult to treat; persistent air leaks; leading cause of pneumothorax in HIV-positive patients
• Tuberculosis - ~7% of HIV patients with pulmonary TB develop pneumothorax; leading cause of SSP in developing countries along with lung abscess

Interstitial Lung Diseases

• Sarcoidosis
• Idiopathic pulmonary fibrosis (IPF)
• Lymphangioleiomyomatosis (LAM) - proliferation of smooth muscle cells causing cystic lung destruction; almost exclusively in women of reproductive age
• Tuberous sclerosis - pulmonary involvement with cysts
• Pneumoconioses
• Eosinophilic granulomatous disease (e.g., Langerhans cell histiocytosis)

Neoplasms

• Primary lung cancers - cavity formation or subpleural tumor rupture
• Pulmonary or pleural metastases

Connective Tissue Diseases

• Marfan syndrome
• Ehlers-Danlos syndrome - defective collagen in lung parenchyma
• Scleroderma
• Rheumatoid arthritis

Miscellaneous

• Pulmonary infarction (from PE)
• Endometriosis - see catamenial pneumothorax below

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3. TRAUMATIC PNEUMOTHORAX

A. Non-Iatrogenic Traumatic

• Stab wounds, gunshot wounds
• Air enters directly through chest wall OR leaks from a disrupted tracheobronchial tree
• If the chest wall defect is larger than the tracheal diameter (~2 cm), air is preferentially inspired through the chest wall wound ("open/sucking chest wound")

• Rib fracture lacerating the visceral pleura
• Importantly: in ~50% of blunt-trauma pneumothoraces, there are no associated rib fractures - common with blast injuries and high-altitude falls
• Sudden compression can rupture alveoli even without structural rib injury
• Occult pneumothorax - seen on CT but not on initial CXR; majority can be managed conservatively in stable patients

B. Barotrauma (from Mechanical Ventilation)

• Incidence: 4-15% on mechanical ventilation; higher with underlying inflammatory disease (ARDS)
• High ventilatory pressures rupture alveoli - the air tracks along bronchovascular sheaths to the mediastinum (pneumomediastinum) and then into pleural space
• Can rapidly progress to tension pneumothorax

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4. IATROGENIC PNEUMOTHORAX

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5. TENSION PNEUMOTHORAX

• Mediastinal shift to contralateral side
• Compression of mediastinal venous structures (SVC, IVC)
• Impaired venous return → cardiovascular collapse and death if untreated

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6. CATAMENIAL PNEUMOTHORAX

• Definition: Recurrent pneumothorax associated with pleural or diaphragmatic endometriosis, occurring within 72 hours before or after onset of menstruation
• Almost always right-sided (due to diaphragmatic endometrial implants)
• Mechanism: Rupture of endometrial nodules on the diaphragm or visceral pleura at the time of menstruation → air leaks from peritoneal cavity into pleural space via diaphragmatic defects
• Treatment: Excision/ablation of endometrial lesions, hormonal suppression, repair of diaphragmatic defects

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Summary Table

Formula

Examples

Clinical Significance

• Quantify cumulative tobacco exposure in a standardized way
• Lung cancer screening: The USPSTF recommends annual low-dose CT screening for adults aged 50-80 years with a ≥20 pack year history who currently smoke or quit within the past 15 years
• COPD risk stratification - significant COPD risk begins around 10-20 pack years
• Surgical risk assessment - heavy smoking history (>20 pack years) increases perioperative pulmonary complications
• Bladder, head & neck, esophageal cancer risk assessment

A person who smoked 40 cigarettes/day for 30 years has: (40 ÷ 20) × 30 = 60 pack years - considered a very heavy smoker with high lung cancer and COPD risk.