PHYSICAL SIGNS OF BRONCHIAL FOREIGN BODY
In most cases there will be limitation of expansion on the invaded side, even though the foreign body is of such a shape as to cause no bronchial obstruction. It has been noted frequently in conjunction with the presence of such objects as a common straight pin in a small branch bronchus. This peculiar phenomenon was first noted by Thomas McCrae in one of the author's cases and has since been abundantly corroborated by McCrae and others as one of the most constant physical signs.
To understand the peculiar physical findings in these cases it is necessary to remember that the bronchi are not tubes of constant caliber; there occurs a dilatation during inspiration, and a contraction of the lumen during expiration; furthermore, the lumen may be narrowed by swollen mucosa if the foreign body be of an irritant nature. The signs vary with the degree of obstruction of the bronchus, and with the consequent degree of interference with aeration and drainage of the subjacent portion of the lung. We have three definite types which show practically constant signs in the earlier stages of foreign body invasion.
1. Complete bronchial occlusion.
2. Obstruction complete during expiration, but allowing the passage
of air during the bronchial dilatation incident to inspiration,
constituting an expiratory valve-like obstruction.
3. Partial bronchial obstruction, allowing to-and-fro passage of
air.
1. Complete bronchial obstruction is manifested by limitation of expansion, markedly impaired percussion note, particularly at the base, absence of breath-sounds, and rales on the invaded side. An atelectasis here exists; the air imprisoned in the lung is soon absorbed, and secretions rapidly accumulate. On the free side a compensatory emphysema is present.
2. Expiratory Valve-like Obstruction.—The obstructed side shows marked limitation of expansion. Percussion is of a tympanitic character. The duration of the vibrations may be shortened giving a muffled tympany. Various grades and degrees of tympany may be noted. Breath sounds are markedly diminished or absent. No rales are heard on the invaded side, although rales of all types may be present on the free side. In some cases it is possible to hear a short inspiratory sound. Vocal resonance and fremitus are but little altered. The heart will be found displaced somewhat to the opposite side. These signs are explained by the passage of some air past the foreign body during inspiration with its trapping during expiration, so that there is air under pressure constantly maintained in the obstructed area. This type of obstruction is most frequently observed when the foreign body is of an organic nature such as nut kernels, beans, corn, seed, etc. The localized swelling about the irritating foreign body completes the expiratory obstruction. It may also be present with any foreign body whose size and shape are such as to occlude the lumen of the bronchus during its contracted expiratory phase. It was present in cases of pebbles, cylindrical metallic objects, thick tough balls of secretion etcetera. The valvular action is here produced most often by a change in the size of the valve seat and not by a movement of the foreign body plug. In other cases I have found at bronchoscopy, a regular ball-valve mechanism. Pneumothorax is the only pathologic condition associated with signs similar to those of expiratory, valve-like bronchial obstruction by a foreign body.
3. Partial bronchial obstruction by an object such as a nail allows air to pass to and fro with some degree of retardation, and impairs the drainage of the subjacent lung. Limitation of expansion will be found on the invaded side. The area below the foreign body will give an impaired percussion note. Breath-sounds are diminished in the area of dullness, and vocal resonance and fremitus are impaired. Rales are of great diagnostic import; the passage of air past the foreign body is accompanied by blowing, harsh breathing, and snoring; snapping rales are heard usually with greatest intensity posteriorly over the site of the foreign body (usually about the scapular angle).
A knowledge of the topographical lung anatomy, the bronchial tree, and of endoscopic pathology* should enable the examiner of the chest to locate very accurately a bronchial foreign body by physical signs alone, for all the significant signs occur distal to the foreign body lodgment.
* Jackson, Chevalier. Pathology of Foreign Bodies in the Air and Food
Passages. Mutter Lecture, 1918. Surgery, Gynecology and Obstetrics,
March, 1919. Also, by the same author, Mechanism of the Physical Signs
of Foreign Bodies in the Lungs. Proceedings of the College of
Physicians, Philadelphia, 1922.
The asthmatoid wheeze has been found by the author a valuable confirmatory sign of bronchial foreign body. It is a wheezing heard by placing the observer's ear at the open mouth of the patient (not at the chest wall) during a prolonged forced expiration. Thomas McCrae elicits this sign by placing the stethoscope bell at the patient's open mouth. The quality of the sound is dryer than that heard in asthma and the wheeze is clearest after all secretion has been removed by coughing. The mechanism of production is, probably, the passage of air by a foreign body which narrows the lumen of a large bronchus. As the foreign body works downward the wheeze lessens. The wheeze is often so loud as to be heard at some distance from the patient. It is of greatest value in the diagnosis of non-roentgenopaque foreign body but its absence in no way negates foreign body. Its presence or absence should be recorded in every case.