# Pulmonology

> Respiratory Anatomy & Physiology

- Skill: `neuralblitz/pulmonology` (Agent Skill)
- Install (CLI): `npx skillmds@latest add neuralblitz/pulmonology`
- Raw SKILL.md: https://api.skillmd.com/api/skills/neuralblitz/pulmonology/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: NeuralBlitz (https://skillmd.com/u/neuralblitz)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/neuralblitz/pulmonology

---


## Respiratory Anatomy & Physiology

### Pulmonary Ventilation

|Parameter|Definition|Normal Value|
|---------|-----------|-------------|
|Tidal volume (TV)|Volume of each breath at rest|500 mL|
|Inspiratory reserve volume (IRV)|Maximal inspiratory effort|3000 mL|
|Expiratory reserve volume (ERV)|Maximal expiratory effort|1200 mL|
|Residual volume (RV)|Volume remaining after max expiration|1200 mL|
|Total lung capacity (TLC)|Maximal lung volume|6000 mL|
|Vital capacity (VC)|Maximal voluntary ventilation|4800 mL|

### Gas Exchange

```
Alveolar Gas Equation:
PAO₂ = FiO₂ × (Patm - PH₂O) - (PaCO₂ / RQ)

Where:
- FiO₂ = Fraction inspired O₂ (0.21 at sea level)
- Patm = Atmospheric pressure (760 mmHg at sea level)
- PH₂O = Water vapor pressure (47 mmHg at 37°C)
- RQ = Respiratory quotient (~0.8)

Normal PAO₂: ~100 mmHg
Normal PaO₂: 80-100 mmHg (declines with age)
```

### Ventilation-Perfusion (V/Q) Matching

|Region|V/Q Ratio|Implication|
|------|---------|-----------|
|Normal lung base|~0.8|Optimal matching|
|Lung apex|>3.0|Wasted ventilation (high V/Q)|
|Lung base|<0.8|Wasted perfusion (low V/Q)|
|Shunt|V/Q = 0|No gas exchange (e.g., ARDS)|

---

## Pulmonary Function Testing

### Spirometry

```
Flow-Volume Loop Interpretation:

      Inspiratory    ┌──────┐   ┌──────────┐
      limb           │      │   │          │
                     │      │   │          │
                     │      │   │          │
                     │      │   │          │
                     └──────┴───┘          │
                    └──────────────────────┘
                         Expiratory limb

Obstructive:  Scooped ("festoons"), reduced FEV1/FVC
Restrictive:  Tall/narrow, preserved FEV1/FVC, reduced volumes
```

|Parameter|Obstructive|Restrictive|
|---------|------------|-----------|
|FVC|Normal or ↓|↓ Markedly|
|FEV₁|↓ Markedly|↓ Proportionally|
|FEV₁/FVC|↓ (<70%)|Normal (>70%)|
|TLC|Normal or ↑|↓|
|RV|Normal or ↑|↓|
|DLCO|Normal or ↓|Normal or ↓|

### Lung Volumes

|Volume|Definition|Clinical Significance|
|-------|-----------|---------------------|
|Functional residual capacity (FRC)|RV + ERV|Body pletysmography measures|
|Total lung capacity (TLC)|All volumes|Serial measurements track disease|
|Diffusing capacity (DLCO)|Gas transfer|Interstitial vs. obstructive|

---

## Obstructive Lung Diseases

### Chronic Obstructive Pulmonary Disease (COPD)

**Definition**: Progressive airflow limitation, not fully reversible, usually progressive, associated with enhanced inflammatory response to noxious particles/gases.

#### GOLD Classification

|GROUP|Symptoms|Spirometry|FEV₁ (% predicted)|
|-----|---------|----------|------------------|
|A|Low risk, few symptoms|FEV₁ ≥ 80%|≥ 80|
|B|Low risk, more symptoms|FEV₁ ≥ 50-79%|50-79|
|C|High risk, few symptoms|FEV₁ 30-49%|30-49|
|D|High risk, more symptoms|FEV₁ < 30%|< 30|

#### Pharmacologic Management

```python
COPD_TREATMENT = {
    "short-acting_bronchodilators": {
        "SABA": ["albuterol", "salbutamol"],
        "SAMA": ["ipratropium"],
        "use": "Rescue therapy"
    },
    "long-acting_bronchodilators": {
        "LABA": ["salmeterol", "formoterol", "indacaterol"],
        "LAMA": ["tiotropium", "umeclidinium", "glycopyrronium"],
        "use": "Maintenance therapy"
    },
    "inhaled_corticosteroids": {
        "indications": ["History of ≥2 exacerbations/yr", "Elevated eosinophils"],
        "examples": ["fluticasone", "budesonide"]
    },
    "triple_therapy": {
        "components": ["LABA + LAMA + ICS"],
        "indications": ["Group D COPD", "Frequent exacerbations"]
    }
}
```

### Asthma

**Definition**: Chronic inflammatory disorder of airways, reversible airflow obstruction, airway hyperresponsiveness.

#### Asthma Control Test (ACT)

|Score|Control Level|Action|
|-----|-------------|------|
|25|Well-controlled|Maintain therapy|
|20-24|Well-controlled|May step down|
|15-19|Not well-controlled|Step up therapy|
|<15|Very poorly controlled|Urgent action|

#### Stepwise Asthma Management

|Step|Treatment|Notes|
|-----|---------|-----|
|1|SABA PRN|Low-dose ICS PRN as needed|
|2|Low-dose ICS|Or LTRA|
|3|Medium-dose ICS + LABA|Consider adding LAMA|
|4|High-dose ICS + LABA|Add LAMA|
|5|Add oral montelukast|Refer for OCS, consider biologics|
|6|Add oral corticosteroids|Biologic therapy|

---

## Restrictive Lung Diseases

### Interstitial Lung Diseases (ILD)

|Category|Examples|Key Features|
|---------|--------|-------------|
|Idiopathic pulmonary fibrosis (IPF)|Usual interstitial pneumonia (UIP)|Honeycombing, basilar|
|Sarcoidosis|Non-caseating granulomas|Lymphadenopathy, upper lobe|
|Hypersensitivity pneumonitis|Bird fancier's lung|Exposure history|
|Connective tissue disease-associated|RA-ILD, SSc-ILD|Underlying autoimmune disease|
|Drug-induced|Bleomycin, methotrexate|Medication history|

### Pulmonary Function in Restriction

```
Pattern: ↓ TLC, ↓ FVC, ↓ FEV₁, Normal FEV₁/FVC ratio

Severity (TLC % predicted):
- Mild: 65-80%
- Moderate: 50-64%
- Severe: <50%
```

### High-Resolution CT (HRCT) Patterns

|Pattern|Characteristics|Differential|
|-------|---------------|-----------|
|UIP/IPF|Honeycombing, reticulation, traction bronchiectasis|Idiopathic pulmonary fibrosis|
|COP|Cryptogenic organizing pneumonia|Bilateral consolidations|
|NSIP|Ground-glass, reticulation, relatively preserved|Symmetric, lower lobe|
|LIP|Lung cysts, ground-glass|Diffuse, thin-walled cysts|

---

## Respiratory Failure

### Type I vs. Type II

|Type|pO₂|pCO₂|Examples|
|----|----|-----|--------|
|I (hypoxemic)|< 60 mmHg|Normal or ↓|PE, ARDS, pneumonia, edema|
|II (hypercapnic)|< 60|> 50|COPD exacerbation, obesity hypoventilation|

### Acute Respiratory Distress Syndrome (ARDS)

**Berlin Definition**:

|P|O₂ Requirement|
|---|---|
|Mild|PaO₂/FiO₂ 200-300 mmHg with PEEP ≥ 5|
|Moderate|PaO₂/FiO₂ 100-200 mmHg with PEEP ≥ 5|
|Severe|PaO₂/FiO₂ < 100 mmHg with PEEP ≥ 5|

**Etiology**:
- Direct: Pneumonia, aspiration, near-drowning, inhalation injury
- Indirect: Sepsis, transfusion, pancreatitis, trauma

---

## Sleep-Related Breathing Disorders

### Obstructive Sleep Apnea (OSA)

**Diagnosis**: AHI ≥ 5 events/hour with symptoms, or AHI ≥ 15 events/hour regardless of symptoms

|Event|Type|Definition|
|------|-----|----------|
|Apnea|Cessation|≥ 10 seconds|
|Hypopnea|Decrease|≥ 30% + 3% desaturation or arousal|
|RDI|Apnea + hypopnea|Events per hour|

### Treatment Options

|Treatment|Indication|Notes|
|---------|-----------|-----|
|CPAP|First-line OSA|Standard pressure 5-20 cmH₂O|
|BiPAP|Ventilatory failure|CPAP failure, overlap syndrome|
|MAD|Dental|OAS mild-moderate|
|Surgery|UPPP|Palatal surgery|
|Weight loss|All overweight|5-10% improvement|

---

## Pulmonary Imaging

### Chest X-Ray Patterns

|Pattern|Radiographic Appearance|Clinical Correlation|
|-------|------------------------|---------------------|
|Consolidation|Airspace opacity, air bronchograms|Pneumonia, edema, hemorrhage|
|Interstitial|Reticular, nodular|ILD, heart failure|
|Cavitation|Central lucency|Lung abscess, TB, tumor|
|Pleural effusion|Blunted costophrenic angle|Transudate vs. exudate|
|Pneumothorax|Visceral pleural line, no lung markings|Trauma, spontaneous|

### CT Pulmonary Angiography (CTPA)

**Indication**: Suspected pulmonary embolism

|Finding|Sensitivity|Specificity|
|--------|------------|------------|
|Central PE|83-100%|89-97%|

---

## Common Errors to Avoid

1. **Confusing obstructive vs. restrictive patterns** — Always look at FEV₁/FVC ratio and TLC
2. **Ignoring DLCO** — Essential for differentiating emphysema vs. chronic bronchitis
3. **Missing hypoxemia triggers** — Consider altitude, V/Q mismatch, shunt
4. **Inadequate rescue inhaler technique** — Check technique at each visit
5. **Underestimating sleep apnea** — Screen all snorers, especially with hypertension
6. **Delayed biopsy in ILD** — Consider multidisciplinary discussion
7. **Oxygen prescription errors** — Target SpO₂ 88-92% for COPD, 94-98% for others
8. **Ignoring vaccination status** — Influenza annually, pneumococcal per guidelines