Respiratory System

ANATOMY

The chest or thorax is a cage of bone, cartilage, and muscle used to expand the lungs. It is made up of the sternum, 12 pairs of ribs attached by the costal cartilage anteriorly and to the 12 thoracic vertebrae posteriorly. Muscles of respiration are the diaphragm and intercostal muscles of the rib cage. There are three major divisions of the chest, the right and left pleural cavities each containing a lung and the medistinum located between the lungs containing the heart.
The trachea and bronchi form a tree like structure that transports air from the environment to the alveoli. The trachea branches into bronchi and then into bronchioles terminating in the alveoli where the oxygen and carbon dioxide exchange takes place. The bronchioles have smooth muscle wrapped around them and are lined by a mucous membrane.
The pleura are serous membranes that line the thoracic cavity and cover the lungs. Parietal refers to wall; therefore the layer that lines the walls of the chest is called the parietal pleura. The layer that covers the lung is called the visceral pleura. Between these layers is the intraplueral space occupied only by a thin film of lubrication fluid. This space is a potential space not normally present unless air gets in between the layers.

PHYSICAL EXAMINATION

To be able to communicate the location of abnormal findings in the chest you must know the location of imaginary lines of reference drawn to the chest. Become familiar with these:

1. Midsternal Line
2. Midclavicular Line
3. Anterior Axillary Line
4. Midaxillary Line
5. Posterior Axillary Line
6. Scapular Line

1. Sternal angle of the angle of Louis
2. Suprasternal notch
3. 2nd Rib-found lateral to the sternum angle of Louis. Below it is the 2nd interspace between the ribs. Using two fingers you can "walk" down the interspace.

THE EXAMINATION: Proceed in an orderly way beginning with a complete exam of the posterior chest first, followed by the anterior chest.

1. Inspect: Look for deformity, retractions with inspirations, or a displaced trachea. Observe rate, depth and effort of breathing. Listen for wheezes, etc.
2. Palpation: Check for areas of pain, masses, and feel for the movement of the chest on deep inspiration. Palpate for tactile fremitus (vibrations felt through the chest wall by palpation). Using your palm at the base of the fingers palpate having the patient repeat the words "ninety-nine". Fremitus is decreased with pnuemothorax and increased when transmission of sound is increased as though consolidated lung of lobar pneumonia.
3. Percussion is used to determine if the underlying tissues are air or fluid filled or solid. Using the middle finger's distal joint press firmly on the chest keeping the rest of the hand off. Then strike the DIP joint with your other middle finger tip-movement is from the wrist. Normal lung tissue is resonant. The liver sound is dull. The lungs sound dull when fluid replaces air in the lungs as in pneumonia with infiltrate or with hemothorax. Percuss for diaphragmatic excursion, compare the level of the dullness on full expiration and full inspiration, usually moves up and down 5-6 cm.
4. Ausculatation of lung fields: Abnormal breath sounds of the lungs are of two types:
   1. Crackles (old name was rales): are intermittent, non-musical, very brief sounds. They sound like rubbing hair between your fingers. Notice if they are heard on inspiration or expiration. These sounds are produced when previously closed airways open suddenly in the smaller airways.
   2. Continuous or of longer duration then crackles with a musical sound. There are of two types:
      1. Wheezes: High pitched musical sound caused by relatively high velocity air flow through a narrowed airway.
      2. Rhonci: Deeper, have a snoring quality, caused by the passage of through an airway obstructed by secretions. Tend to disappear after coughing.

Now repeat the examination on the anterior chest:

1. Inspect chest
2. Palpation of chest
3. Palpation of tactile fremitus
4. Percussion of anterior thorax
5. Auscultation of anterior chest

Hospital Corpsman Sickcall Screeners Handbook

Naval Hospital, Great Lakes

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