It is increased in conditions of condensation of the lung or thickening and adhesion of the surfaces of the pleura. It is dimiminished or lost over collections of fluid in the pleura. Variations in vocal fremitus correspond pretty closely with variations in vocal resonance. Sometimes a pleuritic friction-rub can be felt. How is percussion performed?

Percussion may be immediate or mediate. In the former a sharp blow is struck with the tips of the fingers bunched together, or with the palmar surface of the extended fingers.

Mediate percussion is performed by means of a thin, flat plate of ivory or of hard rubber (called a pleximeter), applied over the part to be examined, and a small rubber-tipped hammer (called a plexor).

For many purposes it is preferable to use the extended finger of one hand as a pleximeter, and the index or middle finger (or both) of the other hand as a plexor. Percussion is said to be weak or strong, superficial or deep, according to the energy of the blow of the plexor.

What is to be learned by percussion?

Percussion gives information as to the relative distribution of gases (usually air), fluids and solids in the structures examined. Attention is paid to the quality (or timbre), the pitch and the intensity of sounds.

Percussion of the healthy chest elicits a sound called clear, representing the normal, pulmonary, vesicular resonance. This may be impaired by increased density of the pulmonary tissues or of superjacent structures-as in interstitial pneumonitis, in pleural thickening or when the chest-wall is thickened.

Percussion-dulness is dependent upon a high degree of conden- . sation-as in the solidification of pneumonia, or at the late stage of tubercle-formation.

The sound elicited over solid viscera, as the liver, heart or spleen, or over serous effusions--as in hydrothorax or hydropericardium, or in ascites, is flat.

The sound occasioned by air (or gas) in inclosed spaces larger than the alveoli of the normal lung may be hyper-resonant or tympanitic--as in vesicular emphysema or over the intestines.

An amphoric or metallic sound is elicited by percussion over large closed cavities, with tense walls, containing air— as a distended stomach or a large vomica in the lungs.

A cracked-pot or cracked-metal sound is occasioned by percussing over a cavity of some size, with a small opening, through which air escapes-as in the case of a pulmonary cavity communicating with a bronchial tube.

The percussion-sounds may display alterations in degree or pitch, and in intensity or volume.

Increased density gives heightened pitch-hence a dull sound is higher in pitch than a clear one. The pitch of tympanitic sounds varies. As a rule, it is higher than that of the normal pulmonary resonance. Other things being equal, the greater the volume of matter set in vibration the greater the intensity of the sound.

By mediate percussion with the fingers a sense of elasticity, or of resistance, can be appreciated.

Sometimes auscultation is practised by one while a second at the same time practises percussion-so-called auscultatory percussion.

The percussion sounds elicited during full-held inspiration differ from those elicited during full expiration-so-called respiratory percussion.

How is auscultation practised?

Auscultation, like percussion, may be immediate or mediate. In the former, the ear is directly applied to the part to be auscultated; in the latter, auscultation is performed through the mediation of a stethoscope. Stethoscopes are monaural or binaural. Each has its advantages. The student should ⚫ become familiar with all of the methods of auscultation.

What is to be learned by auscultation?

Auscultation gives information as to the movement of air and fluids, as to the comparative calibers and lengths of the tubes through which the air passes, and as to the presence in the path of the air-current of matters capable of acting the part of reeds in the production of musical tones.

Listening to the normal respiratory sounds one hears a soft,

breezy inspiration-the normal vesicular murmur, followed by a scarcely audible, briefer expiration.

These sounds may be exaggerated-as they normally are in children; hence they are then called puerile.

The respiratory sounds are also intensified in a lung, or in a portion of lung, performing an excess of function-as after violent exercise, or, compensatorily, when the function of the other lung, or of a portion of the same lung, is interfered with by condensation or compression.

The respiratory murmur is enfeebled or wanting when there is an obstruction to the circulation of air in the lung-as in incipient pulmonary tuberculosis, and in occlusion of the airpassages-as by intrathoracic aneurism, or when the air vesicles have lost their elasticity-as in emphysema.

The respiratory murmur is rendered harsh and is heightened in pitch when the bronchial tubes are thickened, and their caliber is narrowed-as in bronchitis. Under similar conditions, rhonchi or dry râles may be heard-sibilant, if generated in the small tubes; sonorous, if generated in the large tubes. Sometimes the sounds are high-pitched and wheezing.

If the vesicular murmur is but partially obliterated, the breathing is called vesiculo-bronchial; or if the bronchial element predominates, broncho-vesicular. When occlusion of the alveoli entirely obliterates the vesicular quality, the breathing is said to be bronchial or tubular or blowing; these terms respectively indicating progressive encroachment upon the integrity of the smaller air-tubes. In case of a cavity in the lung, the breathing may be cavernous; if the cavity have a tense wall and a small orifice of communication with a bronchus, the sound transmitted to the ear is amphoric.

The presence of secretion in the bronchial tubes occasions râles, usually qualified as moist: subcrepitant, if in the smaller tubes, mucous if in the larger.

The presence of fluid in a vomica may give rise to bubbling or gurgling.

The separation of the adherent surfaces of pulmonary alveoli lined by viscid secretion, as in pneumonia, gives rise to the crepitant râle. When isolated softening of pulmonary tubercles

takes place, a sound is generated comparable to that produced when salt is thrown upon fire, or when a few hairs are rubbed together between the fingers-so-called crackling.

When moist râles are heard through solidified pulmonary tissues they are transmitted with a peculiar clearness and with a sort of ringing character. They are then called consonating. In the first stage of pleurisy, before effusion has taken place, and in the third stage, after the fluid poured out has been absorbed, a coarse crackling, or creaking, or rasping sound of pleural friction may be heard.

In case of pneumothorax resulting from the perforation of a pulmonary vomica into the pleural cavity, vibration of the fluid that has been effused sometimes gives rise to metallic tinkling. Under similar conditions, or in case of a large vomica containing considerable fluid, vigorous shaking of the patient, with the ear applied to the chest, may elicit the sound of splashing—the so-called Hippocratic succussion sound.

When the ear is applied to the normal chest of a speaking individual a confused sound is heard—the vocal resonance.

If fluid is effused into the pleural cavity the transmission of the voice is intercepted below the upper level of the fluid. If the pulmonary tissues are solidified, as in pneumonia and tuberculosis, the resonance is increased, constituting bronchophony. When spoken language and whispers can be distinguished, the phenomena are termed pectoriloquy and whispering pectoriloquy respectively. The latter, if circumscribed, is usually indicative of the existence of a cavity in the lung.

When, in the course of pleurisy, a small quantity of fluid has been poured out the voice is transmitted above the level of the fluid with a peculiar bleating character, constituting egophony.

Not only may the character of the breath-sounds be altered, but their rhythm may deviate from the normal. Thus, expiration may be prolonged, as when, as in emphysema, the elasticity of the walls of the alveoli is diminished; or the expiratory sound may be prolonged or jerking, as when, as in the early stages of pulmonary tuberculosis, there is some obstruction to the exit of air.

Acute Pleurisy.

What are the symptoms of acute pleurisy?

Acute pleurisy may set in with a chill and sharp pain in the side, aggravated by the respiratory movements. The dyspnea may be slight or considerable. The temperature rises moderately high; the breathing is feeble, shallow and rapid. There is slight irritative cough, and scanty, frothy expectoration. In the course of a few days the symptoms subside, and at the end of a week or ten days the patient is well. Acute pleurisy may occur as a primary condition. It may follow traumatism or exposure to cold. Quite commonly it is secondary to inflammation of adjacent structures, especially of the lungs. It also occurs in the course of various infectious diseases of nephritis and of rheumatism. Pleurisy may be "dry" or attended with effusion. sion gives rise to respiratory and circulatory embarrassment proportionate to the volume of fluid poured out.

Effu

The fluid poured out may not be readily absorbed. On the contrary, it may remain obstinately persistent. In the course of time, it may become purulent; under other circumstances, it is purulent from the outset; in either case the condition is known as empyema. More commonly, the fluid is absorbed and the two layers of the pleura become adherent, with obliteration of the pleural cavity; in the progress of the case considerable thickening takes place, followed in turn by retraction of the chest. When the effusion is purulent there are repeated rigors, fever, sweats and emaciation; otherwise the health may be preserved, unless the chronic pleurisy is tuberculous. By the action of the heart, pulsation may be imparted to a collection of fluid in the left pleural cavity, so that an aneurism may be simulated. When the collection is purulent, the condition is designated pulsatory empyema.

What are the physical signs of acute pleurisy?

For convenience of study, the physical signs of acute pleurisy may be considered in three stages. In the first, or plastic stage, as the surfaces of the two layers of the pleura, roughened by exudation, slide over one another in inspiration and expiration,