Examination Of The Chest

22.9.06

General principles
• Careful and detailed clinical history basis of chest diagnosis (many physical signs picked up during history).
• Methodical and structured chest examination only way to identify important clinical signs.
• Idea that investigations alone can give you diagnosis is false.

Examination
• Look - general inspection.
• Face and neck.
• Hands - clubbed fingers.
• Chest inspection.
• Listening to breathing sounds at mouth.
• Palpation.
• Percussion.
• Auscultation.

Respiratory system as acoustic organ
Pulmonary acoustics
• Percussion of chest.
• Sound of breathing (mouth and at chest wall).

Percussion
• Chest divided into 2 acoustic chambers separated by mediastinum.
• Impulse contains wide spread of frequencies.
• Resonant frequency of chest cavities excited.
• Most useful when there is an effusion.

Breath sounds heard at chest
Laennec's classification
• Breath sounds bronchial and vesicular.
• Added sounds:
-rales;
-rattles;
-rhonchi.

General principles
• Sound and its analysis.
• Sound sources.
• Transmission of sound.

Sound sources
• Airflow through bronchial tree (higher frequency sound).
• Muscles, joints, heart, lung tissue etc. (lower frequency sounds).

Sounds heard at mouth
• Pants.
• Gasps.
• Sighs and yawns.
• Hisses.
• Sniffles.
• Snores.
• Whistles and grunts.
• Stridor.
• Wheezes.
• Rattles.
• Crackles.

Normal lung sounds (originally called vesicular)
• Low frequency.
• Rustling quality.
• Louder on inspiration.
• Vary according to site.
• Some correlation with airflow.

Tracheal sounds
• Higher intensity.
• Inspiration and expiration separated.
• Wider spread of frequencies.

Bronchial breathing
• Occurs when lunch parenchyma airless and supplying lobar airway patent.
• Sounds like tracheal sounds (high frequency).
• Loud, easily heard sounds.

Voiced sounds
• Measuring transmission characteristics of lung.
• "99."
• Muffled in normal lung.
• Easily heard over consolidated lung.
• Whispering pectoriloquy in consolidation.

Lung classification - additional sounds
• Continuous sounds - high-/low-pitched wheezes.
• Interrupted sounds - coarse/medium/fine crackles.

Wheeze
• Sudden onset.
• Frequency does not change with low-density gases.
• Dynamic phenomena.
• Models associated with airflow limitation.
• Continuous musical sound.
• Lasts >250ms.

Types of wheeze
• Random polyphonic wheezes.
• Expiratory polyphonic wheezes.
• Fixed monophonic wheeze.

Crackles
• Very short discontinuous sounds <20ms.
• Usually inspiratory, but also heard in expiration.
• Thought to be due to airways opening.
• Sound is pressure equalisation or sudden.
• Heard from airways close to stethoscope.

Types of crackles
• Fine end inspiratory (<10ms) associated with restrictive lung disease.
• Coarse early inspiratory associated with severe airflow obstruction (COPD) and bronchiectasis.
• Expiratory crackles - severe disease.

Pleural friction rub
• Occurs with friction between 2 inflamed surfaces of pleura.
• Sounds like creaking leather.