Percussion Note Descriptions on Respiratory Examination
The percussion note on respiratory examination is described using three distinct sound qualities: tympanic (or tympany), resonant, and dull 1, 2.
Standard Percussion Sound Classifications
These three percussion sounds are easily distinguishable by objective measures:
Tympanic: A drum-like, hollow sound typically heard over air-filled structures (e.g., the intestines or gastric bubble). In the chest, an exaggerated tympanic or hyperresonant note suggests pneumothorax 3, 2
Resonant: The normal percussion note heard over healthy, air-filled lung tissue. This represents the baseline sound expected during chest percussion 1, 2
Dull: A flat, thud-like sound heard over solid organs (e.g., liver, heart) or fluid-filled areas. In the chest, dullness suggests pleural effusion, consolidation, or mass 4, 2
Clinical Significance and Diagnostic Utility
Dullness to conventional percussion is the most accurate physical finding for diagnosing pleural effusion (positive likelihood ratio 8.7), making it a clinically useful maneuver 4. When you percuss and hear dullness where you expect resonance, the probability of pleural effusion increases substantially, though radiographic confirmation remains necessary.
Key Clinical Pearls:
Good interobserver agreement exists among clinicians when categorizing percussion notes as dull, resonant, or hyperresonant 2
Pneumothorax detection: In supine patients, percussion over the sternum while auscultating the anterior chest produces an exaggerated, resonant, and booming quality on the affected side with pneumothorax 3
Large pleural effusions can be reliably detected using comparative percussion and shifting dullness 2
Important Limitations:
The physical basis of percussion involves the ease with which the body wall vibrates, influenced by stroke strength, body wall condition, and underlying organs 2. However, topographic percussion (attempting to measure organ spans or borders) has poor reproducibility and should be abandoned 2. The fundamental assumption that sound waves only penetrate several centimeters is incorrect—underlying organs can cause dullness at distant sites 2.