Fig. 2.1 Symbols used in constructing a pedigree chart, with an example. The terms ‘propositus’ and ‘proposita’ indicate the man or woman

identified as the index case, around whom the pedigree chart is constructed. 

88 • The respiratory system

are usually absent. These two causes of absent sounds are

readily distinguished by percussion, which will be resonant with

pneumothorax and completely dull over pleural fluid.

Use of the stethoscope

Remember to wear the stethoscope with the ear pieces facing

forwards to align them with your auditory canal. Normal breath

sounds are relatively quiet, so the greater area of contact offered

by the diaphragm is usually well adapted to chest auscultation.

The two common exceptions are in patients with:

• A cachectic chest wall with sunken intercostal spaces,

where it may be impossible to achieve flat skin contact

with the diaphragm.

• A hairy chest wall, where movement of chest hairs against

the diaphragm are easily mistaken for lung crackles. In

these situations, use the stethoscope bell instead to listen

to the breath sounds.

Breath sounds

As with percussion, the absolute volume and character of breath

sounds in individuals are greatly affected by the thickness,

muscularity and fat content of the chest wall. The symmetry of

sounds is therefore the key feature.

Examination sequence

• Auscultate the apices, comparing right with left, and

changing to the bell if you cannot achieve flat skin contact

with the diaphragm.

• Ask the patient to take repeated slow, deep breaths in

and out through their open mouth. Auscultate the anterior

chest wall from top to bottom, always comparing mirror

image positions on right and left before moving down.

• Use the same sequence of sites as for percussion (see

Fig. 5.16B and C). Do not waste time by listening to

repeated breath cycles at each position, unless you

suspect an abnormality and wish to check.

• Note whether the breath sounds are soft and muffled,

absent, or loud and harsh (bronchial, like those heard over

the larynx). Seek and note any asymmetry and added

sounds (see later), deciding which side is abnormal.

• Auscultate the lateral chest wall in the mid-axillary line,

again comparing right with left before changing level.

normal lung is almost all air. Resonance on percussion together

with unilateral absent breath sounds indicates pneumothorax.

Auscultation

To understand chest auscultation it is necessary to understand

the origin of breath sounds. The tracheobronchial tree branches

23 times between the trachea and the alveoli. This results in an

exponential rise in the number of airways and their combined

cross-sectional area moving towards the alveoli. During a maximal

breath in and out, the same vital capacity (about 5 L of air in

healthy adults) passes through each generation of airway. In

the larynx and trachea, this volume must all pass through a

cross-sectional area of only a few square centimetres and therefore

flow rate is fast, causing turbulence with vibration of the airway

wall and generating sound. In the distal airway, the very large

total cross-sectional area of the multitude of bronchioles means

that 5 L can easily pass at slow flow rates, so flow is normally

virtually silent. The harsh ‘bronchial’ sound generated by the

major airways can be appreciated by listening with the diaphragm

of the stethoscope applied to the larynx (try this on yourself).

Most of the sound heard when auscultating the chest wall

originates in the large central airways but is muffled and deadened

by passage through overlying air-filled alveolar tissue; this, together

with a small contribution from medium-sized airways, results in

‘normal’ breath sounds at the chest wall, sometimes termed

‘vesicular’. When healthy, air-filled lung becomes consolidated

by pneumonia or thickened and stiffened by fibrosis, sound

conduction is improved, and the centrally generated ‘bronchial’

breath sounds appear clearly and loudly on the overlying chest

wall. In the same way, with soft speech (‘say one, one, one’),

the laryngeal sounds are muffled by healthy lung but heard

clearly and loudly at the chest wall overlying consolidation and

fibrosis, due to improved conduction of major airway sounds

through diseased lung.

When there is lobar collapse caused by a proximal bronchial

obstruction, the signs are different from those in simple

consolidation. The usual findings are diminished expansion,

sometimes with chest asymmetry due to loss of volume, dullness

to percussion over the collapsed lobe, and reduced breath sounds

and vocal resonance.

When the lung tissue is physically separated from the chest

wall by intervening air (pneumothorax) or fluid (pleural effusion),

sound conduction is greatly impaired and the breath sounds

A B C

Fig. 5.16 Percussion of the chest. A Technique. B Anterior and lateral sites. C Posterior sites.

Investigations • 89

5

breath sounds). These signs can be confirmed by asking the

patient to generate laryngeal sounds deliberately (‘Please say “one,

one, one” each time I move my stethoscope on the skin’) and

listening on the chest wall in the same sequence of sites used

for breath sounds. The spoken sound is muffled and deadened

over healthy lung, but the spoken sound is heard loudly and

clearly through the stethoscope over consolidation or fibrotic

lung scarring. Consistent with absent breath sounds, vocal

resonance is absent or greatly diminished over pneumothorax

and pleural effusion.

‘Whispering pectoriloquy’ may be used to confirm the same

changes in sound conduction. Whispered speech is muffled to

silence by normal lung but may be heard over consolidated or

scarred lung.

Interpretation of the findings

Review your findings and assemble the positive features you

have uncovered. On completion of the history and examination

you should have a broad idea of the category of respiratory

illness with which you are dealing. As with any system, consider

as you go the likely categories of disease and how these affect

presentation. This approach is summarised in Box 5.6.

Investigations

Selecting the relevant investigation depends on the clinical problem

revealed on history and examination. Investigations are costly

and many carry risks, so choose tests capable of distinguishing

the likely diagnoses and prioritise the most decisive ones. In

respiratory disease, imaging of the lungs is fundamental, but

respiratory function testing is equally important to distinguish

obstructive disease of the airways from the restrictive pattern

seen in many parenchymal diseases, and to quantify the degree

of abnormality. A summary of the appropriate initial investigations

according to the type of respiratory presentation is included in

Box 5.7.

Added sounds

There are three common added sounds: wheezes, crackles

and rubs. Wheeze is a musical whistling sound accompanying

airflow and usually originates in narrowed small airways. It is

most commonly expiratory, due to dynamic airway narrowing

on expiration, but can also occur on inspiration. Usually, multiple

wheezing sounds are heard together (polyphonic wheeze); this

sign is common in asthma, bronchitis and exacerbation of COPD.

A solitary wheeze that is present consistently with each breath and

does not clear with coughing suggests a possible fixed bronchial

obstruction and can be an important sign of underlying cancer.

Crackles accompanying deep breathing are thought to

represent the sudden opening of small airways but sometimes

may indicate secretions in the airways or underlying lung fibrosis.

In healthy people, gravitational compression of the dependent

lung bases often causes a few crackles on the first few deep

breaths; these are of no pathological significance. Crackles that

persist after several breaths and do not clear with a deliberate

cough are pathological. They are graded as ‘fine’, meaning soft,

multiple crackles, to ‘coarse’, indicating loud, scanty crackles

that tend to change with each breath. Showers of fine crackles

during inspiration, resembling the sound made by peeling a

Velcro fastener, are characteristic of interstitial pulmonary fibrosis,

and are most commonly heard at the lung bases posteriorly

and laterally. Fine crackles also occur in pulmonary oedema and

some viral pneumonias. Coarse crackles are generally heard in

patients with significant purulent airway secretions such as those

with bronchopneumonia or bronchiectasis. Inspiratory crackles

are also often heard over the areas of incompletely inflated lung

immediately above a pleural effusion.

Pleural rub is a rasping, grating sound occurring with each

breath and sounding superficial, just under the stethoscope, like

two sheets of sandpaper rubbing together. It indicates pleural

inflammation, usually due to infection, and is often accompanied

by pleuritic chest pain.

Vocal resonance

Breath sounds normally reveal the presence of consolidation or

fibrosis (bronchial breath sounds) or pleural air or fluid (absent

5.6 Categories of respiratory disease and associated features on history and examination

Category of problem Suggestive features on history Suggestive features on examination

Infection: Fever

Acute bronchitis Wheeze, cough, sputum Wheeze

Exacerbation of chronic obstructive

pulmonary disease

Acute-on-chronic dyspnoea Hyperinflation

Pneumonia Pleuritic pain, rusty sputum, rigors If lobar, dull to percussion and bronchial breathing

Malignancy Insidious onset, weight loss, persisting pain

or cough

Cervical lymphadenopathy, clubbing, signs of lobar/lung

collapse ± effusion

Pulmonary fibrosis Progressive dyspnoea Tachypnoea, inspiratory fine crackles at bases, cyanosis

Pleural effusion Progressive dyspnoea Unilateral basal dullness and reduced breath sounds

Pulmonary embolism:

Large Sudden, severe dyspnoea Normal breath sounds

Medium Episodes of pleural pain, haemoptysis Pleural rub, swollen leg if deep vein thrombosis, crackles

if infarct

Multiple small Progressive dyspnoea Raised jugular venous pressure, right ventricular heave,

loud pulmonary second sound

Asthma Atopy, hay fever, pet ownership, variable

wheeze, disturbance of sleep

Polyphonic expiratory wheeze, eczema

90 • The respiratory system

5.7 Selecting investigations for different respiratory presentations

Likely problem from history and examination Appropriate initial investigations Diagnostic value

Infection

(e.g. acute bronchitis, exacerbation of COPD

and pneumonia)

Chest X-ray

O2 saturation or ABG

Sputum and blood culture

Respiratory function

WCC, CRP

Consolidation in pneumonia

Assessment of respiratory failure

Causal infection

Quantification of any COPD

Degree of inflammation

Malignancy Chest X-ray Identification of masses

CT scan thorax + abdomen Staging of extent

Bronchoscopy if central Diagnostic pathology

CT-guided biopsy if peripheral Diagnostic pathology

Respiratory function Fitness for radical therapies

Pulmonary fibrosis/interstitial lung disease Chest X-ray Bi-basal reticular shadows

High-resolution CT thorax Extent and type of disease

Respiratory function Quantification; identification of restrictive pattern

Autoantibodies Identification of any associated connective tissue disease

Pleural effusion Chest X-ray Dense basal fluid pool

Ultrasound-guided aspiration Culture for infection

pH low in empyema

Glucose low in infection

Cytology to identify malignancy

Protein to identify transudate or exudate

CT thorax + abdomen Identification of underlying tumour

Pulmonary embolism d-Dimer Normal if not pulmonary embolism

CT pulmonary angiogram Detection of emboli

Echocardiogram Detection of right ventricular strain

O2 saturation or ABG Assessment of respiratory failure

Asthma Respiratory function:

Peak flow diary