AUSCULTATION: lung with diagram
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lung auscultation sites diagram anterior posterior stethoscope placement
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Lung Auscultation
Technique
Listen at both apices and over upper and lower lobes, anteriorly and posteriorly, during both inspiration and expiration. Use the diaphragm of the stethoscope for higher-pitched sounds and the bell for lower-pitched sounds. Apply the stethoscope directly to skin (not through clothing) in a quiet room. Work from top to bottom, comparing sides symmetrically.
- Start at the apices (above the clavicles)
- Move systematically down: upper lobes, middle lobe/lingula, lower lobes
- Repeat on the posterior chest, starting at T3 level
Surface Projections of Lung Lobes (Auscultation Anatomy)
This is the key diagram for understanding where to place the stethoscope:
Figure 18.2 - Murray & Nadel's Textbook of Respiratory Medicine
Key anatomical landmarks:
- The oblique fissures (both lungs) run from the spinous process of T3 posteriorly to the 6th rib at the midclavicular line anteriorly
- The horizontal fissure (right lung only) lies at the 4th costal cartilage anteriorly, separating RUL from RML
- Posteriorly, nearly all of the visible lung surface is lower lobe - so posterior auscultation is mostly sampling the lower lobes
- Anteriorly, the upper and middle lobes predominate
Abbreviations: RUL = right upper lobe, RML = right middle lobe, RLL = right lower lobe, LUL = left upper lobe, Ling = lingula (left upper lobe), LLL = left lower lobe
Classification of Lung Sounds
(Based on ATS/Murray & Nadel's standardized nomenclature)
| Lung Sound | Acoustic Characteristics | Significance |
|---|---|---|
| Normal breath sounds | 200-600 Hz; soft, non-musical; louder on inspiration | Normal; arise from turbulent airflow in lobar/segmental bronchi |
| Tracheal breath sounds | 75-1600 Hz; hollow sound heard in both phases just below sternal notch | Normal over trachea |
| Bronchial breath sounds | Same as tracheal but heard in lung periphery; equal on inspiration & expiration | Consolidation, atelectasis - indicates airless air spaces around patent airway |
| Fine crackles | Discontinuous, soft, high-pitched, short; mid-to-late inspiratory | Opening of collapsed distal airways - fibrosis, atelectasis, heart failure, ILD |
| Coarse crackles | Discontinuous, loud, low-pitched; early inspiratory or expiratory; may clear with cough | Distal airway secretions - bronchitis, COPD |
| Wheezes | Continuous >250 ms; high-pitched (≥400 Hz); hissing quality; mainly expiratory | Airway narrowing - asthma/COPD (diffuse), focal lesion (if unilateral) |
| Rhonchi | Continuous >250 ms; low-pitched (<200 Hz); snoring quality; mainly expiratory | Large airway secretions - bronchitis, COPD; often clears with cough |
| Stridor | Continuous, high-pitched; mainly inspiratory; heard best over neck | Extrathoracic obstruction - anaphylaxis, epiglottitis, foreign body. Needs urgent attention |
| Pleural friction rub | Coarse, grating, creaking sound; heard in both phases | Pleural inflammation - pleuritis |
Important: The old term "rales" is no longer used - replaced by "crackles." The term "vesicular" is also inaccurate (normal breath sounds do not arise from alveoli).
Diagnostic Utility - Auscultatory Finding to Clinical Diagnosis
| Auscultatory Finding | Clinical Correlation |
|---|---|
| Bronchial breathing | Pneumonia, interstitial lung disease |
| Fine crackles | Heart failure, ILD, alveolar filling disorders |
| Coarse crackles | Bronchitis |
| Wheeze | Asthma, COPD, bronchomalacia |
| Rhonchus | Bronchitis, COPD |
| Stridor | Upper airway obstruction (laryngeal/tracheal inflammation, mass, external compression) |
| Absent breath sounds | Pleural effusion, pneumothorax, complete atelectasis |
Classic Findings in Common Pulmonary Disorders
| Disorder | Inspection | Palpation | Percussion | Auscultation |
|---|---|---|---|---|
| Asthma (acute) | Hyperinflation; accessory muscle use | Impaired excursion; decreased fremitus | Hyperresonance; low diaphragm | Prolonged expiration; inspiratory + expiratory wheezes |
| Pneumothorax (complete) | Lag on affected side; increased hemithorax size | Absent fremitus | Hyperresonant / tympanitic | Absent breath sounds |
| Pleural effusion (large) | Lag on affected side | Decreased fremitus; trachea shifted away | Dullness or flatness | Absent breath sounds |
| Atelectasis (lobar) | Lag on affected side | Decreased fremitus; trachea shifted toward affected side | Dullness or flatness | Absent breath sounds |
| Consolidation (pneumonia) | Possible lag/splinting | Increased fremitus on affected side | Dullness | Bronchial breath sounds; bronchophony; pectoriloquy; crackles |
Voice-Generated Sounds (Vocal Resonance)
Associated with consolidation (increased transmission) or effusion/pneumothorax (decreased transmission):
- Bronchophony - spoken "99" sounds clear and loud over consolidated lung (normally muffled)
- Egophony (E-to-A change) - spoken "E" sounds like "A" (nasal, bleating quality) over consolidated lung above a pleural effusion
- Whispered pectoriloquy - whispered words are clearly audible over consolidated lung (normally inaudible)
Sources: Murray & Nadel's Textbook of Respiratory Medicine, Chapter 18 | Goldman-Cecil Medicine, Chapter 71 (Table 7-1)
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