Читать книгу Respiratory Medicine - Stephen J. Bourke - Страница 64

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.