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expanded volume (see Chapter 1). Many of the physical signs of airway obstruction are actually signs of hyperinflation.

Table 2.3 Causes of clubbing

Respiratory

NeoplasticBronchial carcinomaMesothelioma

InfectionsBronchiectasisCystic fibrosisChronic empyemaLung abscess

FibrosisIdiopathic pulmonary fibrosisAsbestosis

CardiacBacterial endocarditisCyanotic congenital heart diseaseAtrial myxoma

GastrointestinalHepatic cirrhosisCrohn’s diseaseCoeliac disease

CongenitalIdiopathic familial clubbing

Look at the chest from the front, back and sides, noting the overall shape and any asymmetry, scars or skeletal abnormality. The normal chest is flattened anteroposteriorly, whereas the hyperinflated chest of COPD is barrel‐shaped, with an increased anteroposterior diameter. In airway obstruction, patients tend to adopt a high shoulder position (assisting the lungs in holding a more inflated volume).

      Watch the pattern of breathing. In health, a breath in takes about as long as a breath out. In airway obstruction, careful observation will reveal the prolonged expiratory phase to respiration. Pursed lips during expiration maintain a positive back pressure, holding small airways open longer, reducing gas trapping and allowing patients with airway obstruction to achieve better tidal ventilation at a more comfortable lung volume.

      Watch the movement of the chest carefully as the patient breathes in and out. The ribs move in a way akin to the handle on a bucket. At low lung volume, the movement is predominantly outward; at high lung volume, it is predominantly upward. If, on observation, the front of the chest is seen to move upward on inspiration, hyperinflation (airway obstruction) is present. Diminished movement of one side of the chest is a clue to disease – on that side (see below). Overall movement is reduced if the lungs have reduced compliance (e.g. fibrosis).

In health, the whole ribcage expands during inspiration, the lower costal margins moving upwards and outwards as the chest expands. This is due to the downward discursion and stiffening of the diaphragm (see Chapter 1). In a chest that is already severely overinflated (e.g. in COPD), inspiration begins with the diaphragm already in a low, flat position. The contraction it undergoes during inspiration therefore tends to pull in the lower costal margin (to which it is attached). This inward movement of the lower costal margin during inspiration appears paradoxical. Costal margin paradox (Fig. 2.3) is the single most reliable sign of airway obstruction. It is both sensitive and specific, and is far more reliable than wheeze. All doctors remember to listen for wheeze; few remember to look for lower costal margin paradox.

      The abdominal wall normally moves outwards on inspiration, as the diaphragm descends. Abdominal paradox, in which the abdominal wall moves inwards during inspiration when the patient is supine, is a sign of diaphragm weakness.

       Palpation

      Every medical student knows to go through the motions of examining chest expansion; few bother to note the findings with much care. That may be because they are unsure of the interpretation or because they are in a hurry to get to auscultation, where they assume they’ll find out what’s actually going on. Symmetry of chest expansion is extraordinarily useful if examined properly. Examine it properly. Interpretation of the finding isn’t difficult: whatever the abnormality (consolidation, collapse, effusion, pneumothorax, etc.), remember this (you may wish to write it down and spend time trying to memorise it): the abnormal side moves less. (It really is that easy!). Of course, that won’t tell you what the abnormality is, but knowing which side the abnormality is on is very useful. Imagine that, on auscultation, the breath sounds on the left are quieter than those on the right. It can be a difficult call to decide whether you’re listening to bronchial breathing on the right or diminished breath sounds on the left. Knowing before you get to auscultation that the left is the abnormal side makes interpretation strangely easy.

Chest movements during respiration are best appreciated by placing the hands exactly symmetrically on either side of the chest, with the thumbs parallel with each other in the midline. The relative movement of the two hands and the separation of the thumbs reflect the overall movement of the chest and any asymmetry between the two sides.

Figure 2.3 Movement of the costal margin. The arrows indicate the direction of movement in normal individuals and in those with airway obstruction (see text). The sign is most easily detected by placing the first and second fingers of each hand in the positions shown (on the costal margin in the positions approximating to the line of the lateral border of rectus abdominis).

      The position of the mediastinum is assessed by locating the tracheal position and the cardiac apex beat. To locate the position of the trachea, first, don’t touch the trachea (not until ‘centre’ has been established). Place the middle finger in the sternal notch (which is, by definition, ‘central’) and, keeping it in the notch, gently slide it back towards the trachea. The position at which the trachea is first felt on the tip of the finger immediately informs you whether the trachea is central or deviated. This technique avoids the uncomfortable poking around that usually accompanies palpation of the trachea. Note the distance between the cricoid cartilage and the sternal notch (normally the width of three fingers). Reduction in the cricosternal distance is a sign of a hyperinflated chest. It is not usually necessary to actually poke three fingers into this space to determine that the distance is less than three finger breadths. When palpating the trachea, it may appear to get ‘tugged’ downward into the thorax during inspiration – tracheal tug. This is an illusion, as the trachea doesn’t actually move but appears to if the sternum and anterior ribs move upwards during inspiration. This upward movement is a sign of hyperinflation (airway obstruction).

      The apex beat is the most inferior and lateral point at which the cardiac impulse can be felt. The intercostal space in which the apex beat is felt should be counted down from the second intercostal space, which is just below the sternal angle, and its location should also be related to landmarks such as the midclavicular or anterior axillary lines. It is normally located in the fifth left intercostal space in the midclavicular line. The mediastinum may be deviated towards or away from the side of disease. For example, lobar collapse may pull the trachea to that side, whereas a large pleural effusion or tension pneumothorax may push the trachea and apex beat away from it.

       Percussion

Percussion over normal air‐filled lung produces a resonant note, whereas percussion over solid organs, such as the liver or heart, produces a dull note. The percussion note over an area of consolidation is dull; over an effusion, the note is particularly dull (‘stony dull’). Hyperresonance may be present in emphysema or over the area of a pneumothorax, although it is rarely a reliable sign. Percussion technique is important and requires practice. The resting finger should be placed flat against the chest wall in an intercostal space (tip: focus on getting the middle phalanx, rather than the whole finger,

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