- Saying “ninety-nine” while palpating the chest wall
- More prominent in men due to lower pitched voices.
- ONLY ASYMMETRICAL FINDING IS SIGNIFICANT.
- Topographical: used to delineate border of heart, liver and diaphragmatic excursions.
- Pleural effusion: stethoscope is placed below 12th rib. Percussion is done from posterior chest from apex to base.
– At some point, the dull sound will change to a clearer one as it approaches the stethoscope. If this happens above 12th rib, it indicates pleural effusion.
- Another version is by listening over the back of chest while tapping over the manubrium.
– Clinician should hear identical sounds in two sides of chest. A decreased intensity indicates ipsilateral disease on that side
– Special types of resonance: Skodaic’s, amphoric
- Resonance heard above the pleural effusion.
- Why? Nobody knows
- Flicking the tense cheek while holding the mouth open mimics the sound
- Indicates presence of cavities.
- A small triangle of dullness at posterior chest contralateral to side of effusion
- Narrow area of resonance between the dullness of neck and shoulder muscles.
- If this resonance is lost, it indicates apical lung diseases.
- Topographic percussion theory
– The characteristics of the underlying organs determine the type of the sounds heard.
- Cage resonance theory (the chest wall is the cage, and how it resonates affects the percussion)
– The type of sounds are also affected by the chest wall and the strength of the stroke.
Cage resonance theory maybe more accurate:
- External pressure on the chest dampens the percussion notes.
- Liver span is SMALLER when percussing with stronger stroke.
– Stronger stroke produces more vibrations and therefore more resonance.
– If according to topographic percussion theory (stronger strokes lead to deeper penetration), the liver span should have been larger.
- Possibly sound transmission circumferentially in chest wall rather than through the lungs
– Heart is not detected. If the sound is transmitted through the lung, some dullness should have been heard in left side of the chest
– Sounds intensity changes during Valsava maneuver which tenses the chest wall.
– Sound intensity recorded when the patient breathes room air and a mixture of oxygen and helium is the same (different gases should have different density and this affects the sound intensity).
So what’s good?
- Only asymmetrical dullness/hyperresonance using comparative percussion maybe ok to detect pulmonary pathologies.
- Auscultatory percussion is also very specific for detecting pleural effusion.
Evidence Based Physical Diagnosis. Steven McGee.