The involve-ment of the muscles in the act of inspiration will be found an unfailing indication of seriously embarrassed respiration, such as occurs in pneumonia, emphysema, pulmonary oedema, advanced tuberculosis, all those diseases of the heart and thorax which impede inspiration (hydro and pneumothorax), and all conditions which obstruct the air passages, as laryngeal oedema, growths, membranous croup, laryngismus, etc. <Callout type="important" title="Important">The enlargement of the thorax takes place in its cross diameters by the raising of the ribs and in its vertical diameter by the lowering of the diaphragm by contraction.</Callout> In regard to the first process, it may be said that all those muscles whose contraction elevates the ribs are muscles of inspiration. However, all such muscles are not habitually used in normal inspiration. 16 FUNCTIONAL DIAGNOSIS Those which ordinarily take part in the process are the costals, intercostals, scaleni and serrati. It must be remembered that the ribs normally slant downward from the spine ventrally, so that when their ventral ends are raised the distance between the spine and the sternum is increased. In like manner, the line of junction between the rib and the spinal tubercle is inclined downward laterally, so that elevation of the rib increases the lateral diameter of the chest. The second process, the descent of the diaphragm is accomplished by the drawing downward of the central tendon. The downward pressure of the dia- phragm on the abdominal organs causes them to bulge the abdomen outward. Diaphragmatic breath- ing is, therefore, called abdominal breathing. The lungs, being adherent on all sides to the chest wall, expand in every direction that the chest en- larges, and fill with air. The muscles, therefore, have to overcome (a) the weight of the ribs and (b) the elastic pull of the lungs. Unequal Expansion of the two sides of the thorax may be due to an impairment of the elasticity of the lung tissue on one side or to an immobility due to the binding down of the pleural sac by old adhesions (in which case the outer wall will be re- tracted as already described), or to effusions or tumors in the thorax (in which case the immobile side will be distended). <Callout type="risk" title="Risk">Unequal expansion can indicate serious underlying conditions, such as pleurisy or tumors.</Callout> FUNCTIONAL DIAGNOSIS 17 Litten's Phenomenon. — In the position of respira- tory rest, the diaphragm lies flat against the thorax from its attachment to about the sixth rib. Upon inspiration this muscular layer 'peels off,' as Cabot says, 'as it descends and allows the lung to take its place.' This 'peeling off' of the thick dia- phragm and its replacement by the line of lighter lung tissue can be seen, in a proper position and light, as a shadow moving down the lower part of the chest wall. In order to perceive this phenomenon, the pa- tient must lie flat on his back, his entire chest bared, his feet turned toward the only source of light in the room, the observer seated at his side, and must take a full breath. The shadow, of course, depends upon the ripple of different level that passes over the chest surface as the thick diaphragm recedes and gives place to the thin lung tissue. In pleuritic adhesions, the movements of the dia- phragm are prevented ; in effusions, emphysema and pneumonia, the diaphragm is separated from the chest wall, hence the shadow is not seen. Solids or fluids under the diaphragm, unless extremely large, do not interfere with its movements. 18 FUNCTIONAL DIAGNOSIS TYPES OF BREATHING. The natural type of breathing is that which starts with the diaphragm, the first perceptible movement being an obtrusion of the abdomen. Thence the process spreads upward, involving the ribs and shoulders. This type is called the abdomino-costal type, and is almost universal among men. In civil- ized women, on the contrary, the diaphragm takes but little part in respiration and the ribs in conse- quence acquire an exaggerated importance; this is called costal breathing. Investigation demonstrates that it is due to a difference of dress, and not to genuine sexual differences. The types may be, and often are, modified by disease. Pathological Variations of Type are seen in certain diseases. In diseases of the chest, where costal expansion causes pain, as in pleurisy, pneumonia, etc., and where intrapulmonary pressure is in- creased, as in hydro or pneumo-thorax and emphy- sema, the diaphragm is the main factor in respira- tion, producing the abdominal type of breathing. In abdominal lesions, on the contrary, such as tumors, ascites or visceral enlargement impeding the movements of the diaphragm, the breathing is most- ly costal. In paralysis of the phrenic nerves the breathing is, of course, costal, and in paralysis of the inter- costals the reverse. The latter is, however, rare except immediately preceding death. FUNCTIONAL DIAGNOSIS 19 Reflex Inspiration. — We have already discussed the question of the automaticity of the respiratory centre. But whether it is normally an automatic center or not, it is undoubtedly a reflex one, in di- rect connection with and subject to reflex stimulation by most, if not all, of the spinal and cranial sensory nerves. This is familiarly illustrated by the muscle- sense, etc. That it is also subject to reflex stimula- tion from the cerebrum is shown by the effects of emotion upon breathing. Naturally, however, one would expect the sen- sory nerves of the respiratory tract to exert the most powerful and constant reflex influence upon the centre, and this is the fact. The branch of the vagus nerve especially, which is distributed to the lung itself, furnishes very important sensory reflex stimulation. Experiment makes it probable that this nerve contains both inhibitory and accelerator fibres, regulating the rhythm of the lungs in much the same way that the inhibitory and accelerator nerves regulate the rhythm of the heart. Peripheral stimulation for this reflex regulation is, of course, furnished by opposite conditions of the lung, col- lapse calling into play the accelerator and disten- sion the inhibitory fibres. Rapid, Shallow Breathing. — The above is un- doubtedly one of the explanations of rapid breath- ing in pathological conditions where only shallow inspirations are possible, as in pneumonia, from consolidation of lung tissue, atelectosis, from alveo- 20 FUNCTIONAL DIAGNOSIS lar collapse, pleurisy, from the pain caused by in- spiration, hydro and pneumo-thorax, from compres- sion, and all diseases of the heart which exert a backward pulmonary pressure. Of course a further explanation is found in the relation of blood oxi- dation to circulation (see below). Pain in the Chest. — As the lungs themselves are supplied with no nerve fibres of pain, any thoracic pain connected with respiration and referred to as 'pain in the lungs' must have its seat in one or other of the serous sacs surrounding the lungs (the pleurae) or in the bronchi. Hence, when any pul- monary disease is accompanied by pain on respira- tion, it is due to an attendant bronchitis or pleurisy. Asthma is a conspicuous illustration of perverted reflex influence upon respiration. Asthma is the re- sult of spasm of the bronchi, and may be excited by nasal obstructions and abnormalities, irritations of fauces and larynx, indigestion and other peripheral stimuli, acting through the respiratory centre in the medulla. Asthma of Renal Diseases is produced by the toxic influence of the blood upon the centre of res- piration direct. ■V H. -W Expiratory Centre. — In normal respiration,, in- spiration is the only active factor, expiration being a purely passive physical process, needing no in- nervation. Hence the automatic centre of respira- tion must be regarded as an inspiratory centre only. FUNCTIONAL DIAGNOSIS 21 However, under certain conditions active expiration does take place, and is always rhythmical and co- ordinated, so that we must suppose it is controlled by a centre; and as after section of the medulla, no expiratory movement has ever been demon- strated, it is reasonable to locate the centre in the medulla. Wherever it is located, it is not normally automatic; and, as Howell points out, 'its activity must be dependent in some way upon that of the inspiratory centre, as even our most violent res- piratory movements show an orderly sequence of inspiration and expiration.' This author suggests that 'the action of the expiratory centre is con- ditioned upon the previous discharge of the in- spiratory centre, just as in the heart beat the con- traction of the ventricle is conditioned upon the previous systole of the auricle. ' The stimulation of the expiratory centre may, in general, be said to con- sist in exaggerations of the stimuli which normally excite the inspiratory centre. Automatic Stimulus. — Automacy is, of course, only another term for 'constant reflex produced by a stimulus originating within the organism.' The automatic action of the respiratory centre de- pends upon such a stimulus. We should naturally expect to find the source of the stimulus in the function which the centre controls, namely, the in- terchange of the gases in the blood, and experiment has demonstrated that it consists chiefly in the ac- cumulation of carbon dioxid in the blood, although 22 FUNCTIONAL DIAGNOSIS the diminution of oxygen also undoubtedly plays a part. The reflex is set going in the newborn child doubtless by the severance of placental circulation and the consequent increase in the carbon dioxid of the blood. Possibly the stimulus of the air and tactile influences to the skin help. Haldane and Priestley (Journal of Physiology, xxxii. p. 225) advance what seems to be definite proof that the activity of the respiratory centre is normally governed by the pressure of carbon diox- ide in the alveolar air and consequently in the ar- terial blood. The experiments consist of careful analyses under a variety of conditions of (a) sam- ples of air at the end of a quick, deep expiration, following inspiration; and (b) samples of air at the end of a deep expiration at the usual time, the aver- age of (a) and (b) being taken as the average alveolar air. Making these tests in conditions of bodily rest (1) at ordinary atmospheric pressure, (2) on top of a mountain, (3) at the bottom of a mine, and (4) in a pressure-chamber they found that the percentage of C0 2 of the alveolar air reduced to a pressure of one atmosphere and a temperature of zero degrees was a constant; the oxygen, how- ever, varied all the way from 10.4 to 26.8 per cent. The ventilation in these cases is to be considered constant. In case of a voluntary increase of fre- quency of respiration the percentage of C0 2 in the alveolar air remains constant; that is, the increase FUNCTIONAL DIAGNOSIS 23 in frequency is balanced by decrease in depth. If the percentage of C0 2 in the inspired air was varied, it was found that so small an increase as .2 per cent in the C0 2 of the alveolar air doubled the ventila- tion of the lungs. Under such conditions the oxy- gen of the alveolar air was always above normal. On doing work the percentage of C0 2 in the alve- olar air is found to be increased. In apnoea the C0 2 of the alveolar air was diminished. Zuntz and Geppert found that the arterial blood, in case of work, contained less C0 2 than when no work was done, and therefore they thought that C0 2 was not the cause of the hyperpnoea of work. But Haldane and Priestley state that while the total C0 2 is diminished in the arterial blood during work because of increased acid production, the pres- sure of free C0 2 on the contrary is increased. They thus dispose of the supposition that some other product of muscular action is the cause of work hyperpnoea and make it probable that C0 2 is the active agent in the stimulation of the respiratory centre. Rapid Breathing in Fevers. — Doubtless the in- creased frequency of breathing in fevers, especially infectious and low grade fevers, where the meta- bolism is rapid, is due in some measure to the ac- cumulation of C0 2 in the blood, acting as an abnor- mally powerful stimulus to the respiratory centre. It would seem, however, that this centre, like most others, can be over-stimulated, for C0 2 narcosis in 24 FUNCTIONAL DIAGNOSIS such fevers slows and enfeebles the respirations and finally paralyzes them. Impure Air. — The same remarks apply to cases of respiring air poor in oxygen and rich in C0 2 . ■W . FUNCTIONAL DIAGNOSIS 25 PRESSURE CONSIDERATIONS. Intrapulmonic and Intra-Thoracic Pressure. — Since the lungs are in communication with the ex- ternal atmosphere, it follows that the air pressure in the lungs at any time of rest, whether at the end of inspiration or expiration, is equal to that of the atmosphere. When the lungs are expanded in in- spiration, their capacity increases more rapidly than the air coming through the narrow glottis can keep pace with, and there is a temporary fall in pressure until the pause at the end of inspiration. Contrari- wise, the recoil of the chest is a little too rapid for the outgoing air to equalize, and there is a rise in pressure. This variation, however, is in normal respiration very slight. In the part of the thorax outside the lungs, on the other hand, since it is protected from atmospheric pressure from outside by the chest-wall, and that which reaches it through the lung-sac is modified by the elastic recoil of the lung, the pressure is always negative. The more the thorax is enlarged, stretch- ing the lungs with it, the more forcibly this elastic recoil is brought into play and the more negative becomes the intra-thoracic pressure. It may at any given moment be represented as that of one atmos- phere less the elasticity of the lungs. Emphysema. — Any influence which interferes with the free expulsion of air through the trachea in- creases the intrapulmonary pressure, and opposes extra resistance to the elastic recoil of the lungs, bringing into play the muscles of forced expiration to drive out the air. If this intrapulmonary pres- sure is kept up for any considerable length of time, the elasticity of the lungs at last becomes seriously impaired and they are no longer properly emptied. As a consequence they are in a constant state of more or less inflation which is known as emphysema. The same result occurs from any pathological proc- ess in the alveoli themselves, which impairs their elasticity ; also physiologically in old age. This condition is seen notably in chronic bronchitis, and bronchial asthma. Vicarious Emphysema is seen in parts of the lungs where the other portions are temporarily or permanently incapacitated, or in one lung where the other is out of commission. The extra duty en- tailed upon the sound area causes an undue infla- tion and retention. Cardiac Involvements. — Sooner or later, of course, the extraordinary and constant expansion of the lung causes a backward pressure upon the pulmo- nary artery and interrupts the cardiac cycle, me- chanically and also by virtue of inadequate oxida- tion of the blood. This is compensated for a time by hypertrophy of the right ventricle, but eventu- ally compensation is broken and stasis ensues. Pneumothorax. — In tuberculosis and other degen- erative processes the pleural sac occasionally rup- tures under slight exertion and air is forced into the thoracic cavity at each inspiration. Or the same result is produced by a penetrating wound of the chest, admitting air from outside. This, of course, immediately raises the intrathoracic pressure to that of the atmosphere, and as this entrapped air does not escape as readily as it enters, the pressure is soon raised above that of the lungs, embarrassing their expansion and the heart action, and causing death if not relieved. Coughing. — Any attempt at expiration with clos- ure of the glottis of course raises the intrapulmonic pressure. A conspicuous and extreme example is seen in the familiar phenomenon of coughing. The irritation of the tubes causes a spasmodic closure of the glottis at the same time a violent effort is made at forced expiration, raising the pressure con- siderably, and resulting in the explosive opening of the glottis and expulsion of air under high pressure which constitutes the noisy 'cough.' During the period of compression pulmonary circulation is in- terfered with, general venous stasis occurs, and if long continued causes cyanosis, and occasionally rupture of one of the vessels. •m *m 'W Suction Effect of Negative Pressure. — From the foregoing it is seen that the large veins above and below the thorax are subject to atmospheric pres- sure; the venae cavae and the right auricle, on the eontrary. are wider a pressure of less than one at- mosphere. This difference in pressure levels acts as a suction influence, assisting the flow of venous blood to the heart. It is, of course, more marked with every expansion of the lung in inspiration which makes the pressure still more negative. In pneumo and hydro-thorax, of course, this suc- tion phenomenon is lacking, because the intratho- racic pressure is raised to the level of, and some- times even higher than, the intrapulmonic. This helps to explain the venous stasis occurring in these conditions. Respiratory Waves of Blood Pressure. — Experi- ments show that during inspiration there is first, at the beginning of the inspiratory act, a slight fall in blood pressure, then a rise; at the beginning of expiration there is a slight rise, followed by a notice- able fall. These phenomena are explained as fol- lows: At the commencement of inspiration the capacity of the lung-capillaries is suddenly increased, lessen- ing peripheral resistance and causing a momentary fall in pressure. This is quickly out-balanced by the following occurrences, both of which tend to raise the pressure: (1) Suction
Key Takeaways
- The diaphragm's 'peeling off' during inspiration can indicate underlying conditions.
- Unequal expansion of the thorax may point to serious issues like pleurisy or tumors.
- Rapid, shallow breathing is often a sign of severe respiratory distress in various diseases.
Practical Tips
- Monitor for signs of unequal chest expansion when assessing patients with respiratory issues.
- Recognize that rapid, shallow breathing can be an early indicator of serious conditions like pneumonia or asthma.
- Use the 'peeling off' phenomenon to assess diaphragm movement and identify potential underlying issues.
Warnings & Risks
- Unequal chest expansion may indicate severe conditions requiring immediate medical attention.
- Rapid, shallow breathing is a critical sign that should not be ignored in emergency situations.
- The 'peeling off' of the diaphragm can only be observed under specific conditions and may not always be visible.
Modern Application
While the historical techniques described in this chapter are rooted in early 20th-century medical understanding, many principles still apply to modern survival preparedness. Understanding respiratory mechanics is crucial for triage during emergencies, whether in a wilderness setting or urban disaster scenario. The knowledge of recognizing signs like unequal chest expansion and rapid breathing can save lives by guiding immediate actions and prioritizing care.
Frequently Asked Questions
Q: What does the 'peeling off' phenomenon indicate?
The 'peeling off' phenomenon, where the diaphragm moves away from the chest wall during inspiration, indicates that the lungs are taking over the space previously occupied by the thick diaphragm. This can be a sign of respiratory distress or underlying conditions like pleurisy.
Q: How can unequal expansion of the thorax be detected?
Unequal expansion of the thorax can be detected by visually inspecting the patient's chest while they are breathing, looking