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Important Notice: Davidson's Is Not in This Library

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Available Respiratory Medicine Resources in This Library

Primary Internal Medicine References

What Harrison's (22e) Covers for Respiratory

• Ch. 37 - Upper Respiratory Symptoms (common cold, sinusitis, sore throat, earache)
• Ch. 83 - Neoplasms of the Lung (NSCLC, SCLC, solitary pulmonary nodule, staging)
• Ch. 297 - Diagnostic Procedures in Respiratory Disease
• Pulmonary Embolism and DVT (with full treatment algorithms: anticoagulation, fibrinolysis, IVC filters, catheter-directed therapy, surgical embolectomy)
• Respiratory Infections (viral, bacterial)
• Respiratory Acid-Base Disorders (acidosis/alkalosis, mixed disorders)
• Hantavirus Pulmonary Syndrome
• Aspirin-exacerbated respiratory disease
• Pulmonary infiltrates in immunocompromised hosts

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What Would You Like to Study?

1. COPD - pathophysiology, diagnosis, GOLD staging, management
2. Asthma - mechanisms, triggers, step therapy, acute severe asthma
3. Pneumonia - CAP, HAP, pathogens, CURB-65, antibiotics
4. Lung Cancer - types, staging (TNM), treatment
5. Pulmonary Embolism - Wells score, diagnosis, anticoagulation
6. Pleural Diseases - effusion, pneumothorax, empyema
7. Interstitial Lung Disease - IPF, sarcoidosis, hypersensitivity pneumonitis
8. Tuberculosis - pathogenesis, diagnosis, treatment regimens
9. Respiratory Failure - type 1 vs type 2, mechanical ventilation
10. Respiratory Physiology - V/Q mismatch, spirometry, ABG interpretation

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Respiratory Diseases - Study Guide

Based on Harrison's Principles of Internal Medicine, 22nd Edition (2025)

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PART 1: RESPIRATORY PHYSIOLOGY (Chap. 295-296)

Core Concept: What the Respiratory System Must Achieve

1. Ventilate the alveoli tidally - fresh gas in, alveolar gas out, alternating at the respiratory rate
2. Match ventilation to perfusion (V/Q matching) - the fresh gas supply to an alveolus must be proportional to its blood flow
3. Allow rapid gas diffusion across the alveolar-capillary membrane (normally ~70 m² surface area within a ~7 L thorax)
4. Scale up several-fold to meet increased metabolic demands

Key fact: V/Q mismatch accounts for essentially ALL of the reduced PaO2 seen in most lung diseases. True shunts (blood bypassing alveoli entirely) cause hypoxia that does NOT correct with supplemental O2.

Three Components of the Respiratory System

Ventilation Key Terms

• FEV1 - volume exhaled in the first second of a forced expiratory maneuver
• FVC - total volume exhaled over the entire forced expiration
• FEV1/FVC ratio - the key discriminator: reduced (<0.70) = obstructive; normal with low FVC = restrictive
• Residual Volume (RV) - air remaining after maximal exhalation
• Total Lung Capacity (TLC) - all air in lungs at maximal inhalation

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PART 2: DIAGNOSTIC PROCEDURES IN RESPIRATORY DISEASE (Chap. 297)

Thoracentesis (Pleurocentesis)

• Purpose: aspirate fluid from the pleural space for diagnosis or symptom relief (most commonly dyspnea)
• Standard of care: always use point-of-care ultrasound to mark the puncture site - reduces dry tap and pneumothorax risk
• Key test: Light's criteria (1972) - still the gold standard for separating exudate from transudate
• Newer marker: Mesothelin-1 - elevated in mesothelioma

Closed Pleural Biopsy

• Percutaneous sampling of the parietal pleura
• Blind biopsy (Abrams needle): highly sensitive for pleural TB (diffuse involvement)
• Image-guided (CT or ultrasound): preferred for focal pleural nodules (virtually pathognomonic for malignancy); diagnostic yield ~80-90%

Thoracoscopy / Pleuroscopy

• Medical thoracoscopy (pleuroscopy): performed by interventional pulmonologist, single port; used for parietal pleural biopsy, lysis of adhesions, pleurodesis, or indwelling pleural catheter placement

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PART 3: ASTHMA (Chap. 298)

Definition and Pathophysiology

• Airway hyperresponsiveness
• Reversible bronchoconstriction
• Airway inflammation

Key Diagnostic Tools

FeNO is easily suppressed by inhaled corticosteroids (ICS). It can be used to check adherence - persistently elevated FeNO on high-dose ICS = poor adherence OR refractory T2 inflammation.

Goals of Asthma Therapy (Table 298-4)

1. Symptoms ≤2 times/week
2. Nighttime awakenings ≤2 times/month
3. Reliever use ≤2 times/week (except pre-exercise)
4. No more than 1 exacerbation/year
5. Normal lung function
6. Normal daily activities
7. Satisfaction with care, minimal side effects

Treatment - Stepwise Approach (GINA/NAEPP 2025 Update)

• ICS = backbone of controller therapy
• LABA (formoterol) = fast-onset LABA, used as both controller and reliever
• LTRA (montelukast) = alternative step 2; NOTE: recent FDA warnings about suicidal ideation
• Biologics (anti-IL-5, anti-IL-4/13, anti-IgE) = step 5, reserved due to high cost; very effective in correct endotypes

Severe Asthma Attack - Key Points

• Assess immediately with peak flow, O2 sats, respiratory rate
• First-line: SABA (salbutamol) + systemic corticosteroids
• Severe/life-threatening: add IV magnesium sulfate, consider heliox, non-invasive ventilation
• Patients at greater risk of asthma mortality: previous near-fatal attack, poor perception of symptoms, psychosocial factors, poor adherence

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PART 4: CHRONIC OBSTRUCTIVE PULMONARY DISEASE (Chap. 303)

Definition

1. Emphysema - destruction of alveolar walls, air space enlargement (anatomic definition)
2. Chronic bronchitis - chronic cough + phlegm for ≥3 months in ≥2 consecutive years (clinical definition)
3. Small airway disease - bronchioles narrowed and reduced in number

Causes

• Cigarette smoking - primary cause in developed countries
• Biomass fuel - major cause globally (cooking fires)
• Vaping, cannabis - increasing concern especially in adolescents
• Abnormal lung development, recurrent infections, asthma, genetics (α1-antitrypsin deficiency)

Pathogenesis

Physiology of COPD

• Airflow obstruction: FEV1/FVC < 0.70 post-bronchodilator (fixed, unlike asthma)
• Hyperinflation: increased RV, increased TLC - compensates for obstruction but flattens the diaphragm
• Flattened diaphragm effects: reduced zone of apposition, shorter fibers, greater tension required, chest wall recoil works against the inspiratory muscles
• PaO2 remains near normal until FEV1 <50% predicted
• PaCO2 elevation not expected until FEV1 <25% predicted
• Cor pulmonale occurs with FEV1 <25% and chronic hypoxemia (PaO2 <55 mmHg)
• V/Q mismatch (not true shunt) causes hypoxemia - explains why modest supplemental O2 corrects it

GOLD Spirometric Severity Staging (post-bronchodilator FEV1/FVC < 0.70)

Clinical Features

• Symptoms: cough, sputum, exertional dyspnea (the cardinal symptom, insidious onset)
• Activities with arm work above shoulder level are especially difficult
• Activities allowing arm bracing (shopping cart, treadmill) are better tolerated
• Signs (advanced): barrel chest, prolonged expiratory phase, expiratory wheeze, hyperresonance to percussion, poor diaphragmatic excursion, tripod position, cyanosis, cachexia
• Clubbing is NOT a feature of COPD - if it develops, investigate for lung cancer
• Cor pulmonale (right heart failure) relatively uncommon since supplemental O2 became widespread

COPD Management - Pharmacologic

Dupilumab (a biologic) is now approved for COPD with high eosinophils - a new addition in 2025.

• Eligibility: serum α1-AT <11 µM (~55 mg/dL) - typically PiZZ genotype
• IV augmentation slows emphysema progression (shown in RCT)
• NOT recommended in those with normal lung function and normal CT scan

COPD Management - Non-Pharmacologic

• Vaccinations: influenza (annual), pneumococcal, COVID-19, RSV, pertussis (if not vaccinated in adolescence)
• Pulmonary rehabilitation: improves QoL, dyspnea, exercise capacity; reduces hospitalizations over 6-12 months
• Lung volume reduction surgery (LVRS): best for upper-lobe emphysema + low exercise capacity post-rehab; NOT if FEV1 <20% + diffuse emphysema on CT or DLCO <20% (high surgical mortality)
• Bronchoscopic lung volume reduction (BLVR): two FDA-approved one-way endobronchial valves; requires absent interlobar collateral ventilation; main complication = pneumothorax (within first 3 days)
• Lung transplantation: second leading indication for transplant overall

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PART 5: HYPERSENSITIVITY PNEUMONITIS (Chap. 299)

Definition

Common Antigens (Table 299-1)

Clinical Patterns

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PART 6: OCCUPATIONAL & ENVIRONMENTAL LUNG DISEASE (Chap. 300)

Key Principle

Key Points for History

• Specific contaminants, visible dust, chemical odors
• Ventilation of workspace, use of respiratory protection
• Temporal association: symptoms improve on weekends/holidays and worsen on return to work = occupational cause
• Hobbies, household exposures, proximity to traffic/industrial sites

Major Occupational Lung Diseases

Spirometry in Occupational Disease

• Obstructive pattern: occupational asthma, COPD
• Restrictive pattern + reduced DLCO: pneumoconiosis, ILD
• Measuring FEV1 before and after a work shift detects acute bronchoconstrictive response

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PART 7: PULMONARY EMBOLISM (PE) - From Chap. 299/300 Block

DVT and PE - Treatment Highlights (Harrison's Chap. 31)

• Massive PE: hemodynamic compromise (hypotension, shock) - highest mortality
• Sub-massive PE: right heart strain without hemodynamic compromise
• Low-risk PE: normal RV function, no hemodynamic compromise

• Non-warfarin anticoagulants (DOACs - rivaroxaban, apixaban, edoxaban): now preferred
• Warfarin: with bridging heparin until INR therapeutic (2-3)

• Upper extremity DVT: managed similarly to lower extremity
• Isolated calf DVT: generally anticoagulate (risk of proximal extension)
• Compression stockings: prevent post-thrombotic syndrome

• Fibrinolysis (systemic thrombolysis): for hemodynamic compromise
• Catheter-directed therapy: lower-dose thrombolysis directly into pulmonary artery
• Surgical pulmonary embolectomy: for massive PE when thrombolysis contraindicated or fails
• Pulmonary thromboendarterectomy: for chronic thromboembolic pulmonary hypertension (CTEPH)
• IVC filters: reserved for patients where anticoagulation is absolutely contraindicated

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PART 8: LUNG CANCER (Chap. 83)

Types

Staging - NSCLC (TNM system)

SCLC Staging (simplified)

• Limited disease: one hemithorax, ipsilateral nodes - can be encompassed in one radiation field
• Extensive disease: beyond one hemithorax or distant mets

Solitary Pulmonary Nodule (SPN)

• Low risk: smooth, small (<8 mm), no growth over 2 years
• High risk: irregular/spiculated margins, size >8-10 mm, growth on serial CT
• Management guided by Fleischner Society guidelines

Screening

• Low-dose CT (LDCT) annual screening recommended for high-risk patients (age 50-80, ≥20 pack-year history, current smoker or quit within 15 years)

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QUICK REFERENCE: Obstructive vs. Restrictive vs. Mixed

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QUICK REFERENCE: Hypoxemia Mechanisms

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CLINICAL PEARLS (High-Yield)

1. Clubbing in COPD = always investigate for lung cancer; clubbing is NOT caused by COPD alone
2. FeNO >35-40 ppb in untreated patient = T2 asthma; guides biologic selection
3. V/Q mismatch is the mechanism of hypoxemia in COPD - it responds to modest supplemental O2
4. GINA 2025: ICS/formoterol as as-needed reliever in ALL steps of asthma, including mild intermittent (Step 1)
5. Dupilumab now approved for COPD with eosinophils ≥300/µL (2024/2025 data)
6. Cor pulmonale in COPD: requires FEV1 <25% AND PaO2 <55 mmHg
7. Farmer's lung vs. Asthma: farmer's lung = systemic (fever, myalgia) hours after exposure; asthma = bronchospasm minutes after exposure
8. Asbestosis: only pneumoconiosis with basilar predominance (vs. silicosis/CWP = upper lobe)
9. Closed pleural biopsy (blind): highly sensitive for TB pleural effusion (diffuse involvement)
10. LVRS contraindications: FEV1 <20% + diffuse emphysema OR DLCO <20% = too high surgical risk

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