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Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 RESTRICTIVE DISEASE

WARREN M. GOLD, M.D.

RESTRICTIVE LUNG DISEASE is a These disorders can be divided into two pattern of abnormal lung function defined by groups: extrapulmonary and pulmonary. a decrease in lung volume (Fig. I).1,2 The In extrapulmonary restriction, an abnormal total lung capacity is decreased and, in severe increase in the stiffness of the chest wall (kypho­ restrictive defects, all of the subdivisions of the scoliosis) restricts the , as does total lung capacity including , respiratory muscle weakness (poliomyelitis or functional residual capacity, and residual vol­ muscular dystrophy). These extrapulmonary ume are decreased. In mild or moderately se­ causes of pulmonary restriction are treated vere restrictive defects, the residual volume may be normal or slightly increased.

CLINICAL DISORDERS CAUSING TABLE 1 CAUSES OF RESTRICTIVE LUNG DISEASE Restrictive lung disease is not a specific clin­ I. Extrapulmonary restriction 3 ical entity, but only one of several patterns of A. Chest wall stiffness (kyphoscoliosis) B. Respiratory-muscle weakness (muscular dystrophy)4 abnormal lung function. It is produced by a C. ()5 number of clinical disorders (see Table 1). II. Pulmonary restriction A. Surgical resection (pneumonectomy)6.7 Dr. Gold: Director, Pulmonary Laboratory and Re­ B. Tumor (bronchogenic carcinoma or metastatic tumor)8 search Associate in Cardiology (Pulmonary Physiology), C. Heart disease (hypertensive, arteriosclerotic, rheu­ Children's Hospital Medical Center; Associate in Pedi­ matic, congenital)9 atrics and Tutor in Medical Science, Harvard Medical 10 11 School, Boston, Massachusetts. D. (viral, bronchial, lobar) . Presented at the Symposium on Chest Disorders in Chil­ E. Granulomatous disorder (, , dren. fungal infections)12 This work was done during the tenure of an Advanced F. (, )13-14 Research Fellowship of the American Heart Association. G. Diffuse interstitial fibrosis (Hamman-Rich syndrome)15 This work was supported in part by Grant HE-10436 H. Collagen disease (lupus erythematosis, scleroderma)16 from the National Heart Institute of the National Institute I. 17>19 of Health.

Volume 48 / Number 5 455 Lung Volumes

Normal Restrictive Lung Disease Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

Fig. 1. A normal spirogram (left) is depicted in relation to the total lung capacity (TLC), vital capacity (VC), junctional residual capacity (FRC=ERV 4- RV), inspiratory capacity (IC), expiratory reserve volume (ERV), and residual volume (RV). A spirogram of the type observed in restrictive lung disease is superimposed on the normal TLC (right). Note the dif­ ference in pattern of (rapid and shallow).

RESTRICTIVE LUNG DISEASE PATHOPHYSIOLOGY OF RESTRICTIVE LUNG DISEASE separately in this symposium.18 Any disorder Lung Volumes of the pleural space (, pneumo­ The vital capacity (the maximum volume thorax, or ) can also lead to a loss of air expired after a maximum inspiration) is of lung volume. always decreased in restrictive lung disease. Pulmonary restriction includes any disorder However, this test of lung volume depends on which causes an actual loss of lung tissue the effort and co-operation of the patient. (tumor, pneumonectomy), loss of air-contain­ Furthermore, it may be abnormally decreased ing alveoli ( or pneumonia), if the residual volume is abnormally increased or loss of lung distensibility (fibrosis, sarcoid­ (hyperinflation) secondary to airway obstruc­ osis, collagen disease). This pattern may tion. It is important, therefore, in the physio­ also result from any of the disorders that pro­ logic diagnosis of pulmonary restriction to duce obstructive airway disease (, measure the total lung capacity (Fig. 2). In , ) when complicated most pulmonary laboratories, this measure­ by atelectasis. The role of the physical ther­ ment is made by a gas dilution method such apist is so important in the treatment of atelec­ as the open-circuit N2 washout method illus­ tasis that this condition is also considered trated in Figure 2, or by a plethysmographic separately in this symposium.10 method.

456 PHYSICAL THERAPY >r 0 Liters Room Air Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

30 Liters

Cone. = 4%

Fig. 2. There are several methods of determining the volume of gas which cannot be expired, but most laboratories use an open-circuit N2 washout method. The volume of gas in the is unknown. When the patient breathes room air, however, this gas is known to contain 80 per cent N2. The amount of N2 in his lungs is determined by washing all the N2 out of the lungs with N2-free 02. The patient inspires 02 and expires through a suitable valve system into a Nz- free (previously flushed with 02) where the volume and N2 concentration of the expired gas is measured. At the beginning of the test all the N2 is in the lungs (grey circles); at the end of the test all the N2 is in the spirometer which contains 30,000 ml of gas and N2 conc. — 4 per cent. The spirometer contains 0.04 X 30,000 ml •=. 1200 ml N2. All this N2 came from the lungs; since 1200 ml N2 existed in the lungs as 80 per cent N,, then the volume 80 of gas in the alveoli at the start of the test was 1200 X JQQ — 1500. Corrections must be made in this volume for small amounts of N2 in the 02 which the subject inspires and for the blood and tissue N2 washed out during the procedure.

Volume 48 / Number 5 457 RESTRICTIVE LUNG DISEASE must be applied to them sufficient to overcome the force with which the springs recoil.* If a second set of stiffer springs is stretched, they Lung generate an even greater recoil force. To Many of the disorders listed in Table 1 not stretch these "stiff" springs to the same length only cause a loss of lung volume, but also alter as the "normal" springs, a much greater force the distensibility of the lungs; the lungs be­ must be applied than was used with the come stiffer than normal.20 The process of "normal" springs. lung inflation is analogous to stretching a set The parenchyma of the lung behaves like of springs (Fig. 3). If the "springs" in Figure a set of springs tending to recoil to its resting 3 are stretched from their rest length (Li) to length (Fig. 4). Stretching the "lung springs" a greater length (L2), they tend to recoil to their resting length with a certain force (F= * An elastic material returns to its original form when Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 the force distorting it is removed. The stretching force recoil force). To stretch the springs, a force on a set of springs is therefore called an elastic force.

"Normal" Springs "Stiff" Springs

/VM /W\A, < L, 4 •< Lji »'

B.

Length

F, F. Force £

Fig. 3. (A) Comparison of "normal" and "stiff" springs. Rest length = Lx, stretched length = L2; recoil force of "normal" springs = F,, recoil force of stiff springs = Fs. (B) Length-force relationships of "normal" and "stiff" springs. To stretch the "stiff" springs a distance equal to the normal springs requires a greater force. Note that the slope of the stiff spring line is decreased compared to the slope of the normal line.

458 PHYSICAL THERAPY A. "Normal" B. Stiff IWWV W\AA/1 PAPP v PAPP ; V, rAA/W/n 5 p; AAAAA

AAAAAAA VWW\A

PAPP v, PAPP- : V2 Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 Q\ '5 P' LA/WWV 2 •WWV\J

Volume

Pressure

Fig. 4. (A) ELASTIC RECOIL PRESSURE OF THE LUNG. The lung is represented by a bellows with a "springs" in its walls. The elastic recoil pressure (P) generated by these lung springs is measured by the manometer in the tube leading to the bellows. The applied pressure (Papp) is supplied by a piston in the tube. Vi and V2 are two different lung volumes, Pt and P2 are the corresponding recoil pressures. The stiff lungs on the right generate a greater-than-normal recoil pressure P' at any lung volume. (B) ELASTIC RECOIL CURVE OF THE LUNG. Volume is on the ordinate and pressure on the abscissa. Note that the stiff lung requires a greater pres­ sure to distend it to the same volume as the normal lung. The slope of the pressure-volume , change in volume ...... , curve or (C = —2—: ) is diminished in the stiff lung. L change in pressure

produces a volume change and generates a may be applied by a ventilator, or by the pressure which makes the lung recoil to its anesthesiologist's hand on the anesthesia bag. resting volume. The magnitude of this elastic Many of the disorders listed in Table 1 change recoil pressure depends on the volume of air the distensibility characteristics of the lung so put into the lung. The more the lung is dis­ that it becomes stiffer than normal (Fig. 4). tended, the greater the recoil pressure generated This means that the elastic recoil curve of the by the "lung springs." To distend the lung, lung is altered (shifted to the right and below a pressure must be applied that is sufficient to the normal range) so that at any given volume, overcome this recoil pressure. This applied the "stiffer" lung requires a greater than pressure is usually produced by the muscles normal pressure to produce a comparable de­ of respiration, but in the patient, this pressure gree of distention or volume.

Volume 48 / Number 5 459 I RESTRICTIVE LUNG DISEASE ^ Diffusion Defect Another important feature of restrictive lung disease is an impaired capacity of the lung to Unevenness transfer gas from the air spaces to the red The most important characteristic of the cells in the pulmonary capillaries.23-25 This ca­ restrictive defect is unevenness.21, 22 The dis­ pacity, called the pulmonary , tribution of the pathologic process, even in the can be measured. In most pulmonary labora­ diffuse fibrotic diseases, is uneven. Some air tories, the diffusing capacity is now measured spaces are stiffer than others, some may be with carbon monoxide as illustrated in Figure completely collapsed, others may be relatively 6. A low concentration of CO is introduced normal. Some blood vessels are wide open, into the air spaces by adding about 0.4 per cent some are narrowed, and some may be obliter­ CO to the inspired air. The concentration of ated by the underlying disease process. Thus, CO entering the pulmonary capillary is zero. Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 the distribution of both ventilation and per­ The CO molecules pass across the membrane fusion within the lung is uneven and the bal­ and dissolve in the blood plasma. CO com­ ance between ventilation and becomes bines chemically with special sites on the abnormal. The possible consequences of this molecule with 210 times the affin­ unevenness on is illustrated in ity of 02 for these receptor sites; therefore, Figure 5. Some air spaces are hypoventilated CO molecules combine instantly with hemo­ relative to their perfusion (A); some are not globin in the red cells in the pulmonary capil­ ventilated at all, but are perfused (B); some laries. The affinity of CO for hemoglobin is are ventilated but poorly perfused (C); or not so great that the receptor sites for CO on the perfused at all (D); some are ventilated and hemoglobin molecule cannot be filled by the perfused normally (E); and some are neither number of CO molecules crossing the alveolar- ventilated or perfused (F). capillary membrane in the available time. CO transfer is limited only by the speed of diffusion across the membrane. If the concentration of hemoglobin, the number of patent capillaries, and the size and physical chemistry of the alveolar membrane, is normal, CO transfer can be normal for sixty seconds, even if pulmonary blood flow is stopped. Diffusion defects may be observed in many different disorders including pulmonary edema, pulmonary emboli, collagen diseases, and sili­ d-\ cosis or asbestosis. Regulation of Respiration Patients who suffer from pulmonary restric­ \=o( (A tion usually breathe in a characteristic pattern. Their is increased and tidal 15,26 volume is decreased. The arterial C02 f pressure is often subnormal because these ^f| \ patients hyperventilate, i.e., their alveolar ven­ tilation is greater than necessary to remove the C02 produced and the arterial C02 pres­ sure is decreased as a result. The neuro- anatomic basis for this pattern of respiration Fig. 5. Unevenness of distribution of ventila­ is not clear in all cases. In some patients, it tion and perfusion in restrictive lung disease. may be related to hypoxemia (decreased levels Each element in the figure represents an air­ of 02 in the arterial blood). Decreased arterial space and its blood supply. The normal unit Oo pressure stimulates special cells in the is labelled (E). Any shading superimposed on carotid body which, in turn, stimulates the such a unit represents a relative decrease in to increase ventilation. In ventilation or perfusion or both. Element (F) other patients, the hyperventilation may be is neither ventilated nor perfused. related to changes in lung distensibility.

460 PHYSICAL THERAPY A Normal

CO

Alveolus

—Plasmo • —Hemoglobin • Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

((((( Fig. 6. Pulmonary Diffusing Capacity. Black B. Membrane Defect circles represent CO molecules. The bottom of each alveolus represents the alveolar-cap­ illary membrane (actually consisting of sev­ eral boundary layers including red blood cell, plasma, capillary membrane, interstitial fluid, • Alveolus . and alveolar membrane) containing many pores for molecular gas diffusion. Blood

—Plasmo moves from right to left through the pul­

—Hemoglobin monary capillary. The size of the arrow is • u u proportional to the size of the blood flow. The blood compartment is divided into two parts; the upper part represents plasma with a limited number of pockets or receptor sites for CO. The bottom part represents hemoglobin with C. Decreased Pulmonary Capillary Blood Volume a large number of receptor sites or pockets for CO. The figure on the top represents the normal lung. The center figure represents the lung in which the membrane is abnormal, e.g., fibrosis or edema. The figure on the bot­ Alveolus tom represents the lung with pulmonary capil­ lary obstruction. (Modified after The Lung,

Plasma Second Edition, by Julius H. Comroe, Jr., et al.

Hemoglobin Copyright 1962, Year Book Medical Publish­ ers, Inc. Used by permission of Year Book Medical Publishers.)

Consider the effect of slowly and generated during breathing (Fig. 7). deeply for the patient with restrictive lung However, the patient pays a price for this disease (Fig. 7). If the patient breathes pattern of breathing. The volume of the air­ slowly, he must breathe deeply to maintain ways (, bronchi, and bronchioles) the same minute volume of ventilation. By changes very little as decreases. breathing deeply, however, increased work Thus, a larger fraction of each tidal breath must be expended to stretch the "lung springs." (VT) washes back and forth through the con­ If those "springs" are stiffer-than-normal, the ducting air passages, but fails to reach gas- work of breathing will be abnormally increased. exchanging portions of the lung and is truly Thus, by increasing the rate and decreasing wasted ventilation (VD) (Fig. 8). the tidal volume, the patient with "stiff lungs" By some undefined nervous mechanism, the could decrease the amount of work or pressure patient with pulmonary restriction learns to

Volume 48 / Number 5 461 Work Recoil Pressure Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

10 20 30 40

Respiratory Rate

Minute Ventilation Rate x Tidal Volume (liters/minute) (breaths/minute) (liters) 8 10 x 0.800 8 20 X 0.40 0 8 40 X 0.200

Fig. 7. Relationship Between the Work of Breathing, Lung Recoil Pressure, and Respira­ tory Rate. The work of breathing and recoil pressure are in arbitrary units on the ordinate. The respiratory rate (breaths per minute) is on the abscissa. In order to keep the at 8 liters/minute, if tidal volume decreases, the rate of breathing must increase. By decreasing the tidal volume, the patient with restrictive disease decreases the amount of work or pressure generated to distend his "stiff" lungs.

RESTRICTIVE LUNG DISEASE ventilated relative to their perfusion; a de­ creased amount of 02 is added to the mixed venous blood passing by these airspaces and minimize the work or pressure or both needed blood low in 02 content is mixed with normally to overcome the abnormal stiffness of his lungs oxygenated blood from other areas of lung without unduly increasing his ven­ resulting in systemic hypoxemia. In addition, tilation by breathing too shallowly. In fact, some areas of lung may not be ventilated at most of these patients manage to maintain all, but still perfused, e.g., atelectasis or pneu­ normal C02 elimination throughout the course monia. The effect is physiologically analogous of their disease. Hypoxemia and Hypercapnea. Patients with TABLE 2 these conditions may develop hypoxemia, i.e., HYPOXEMIA (DECREASED ARTERIAL P02) abnormally decreased 02 content and pressure • Decreased ventilation of perfused lung units. of systemic arterial blood (Table 2). The • No ventilation of perfused lung units. most common cause of the hypoxemia is un- • Diffusion defect (blood passes alveolar membrane too evenness in the distribution of ventilation and fast for equilibration of 02 with red cells). perfusion.27 Some areas of lung are poorly • Hypoventilation.

462 PHYSICAL THERAPY Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

Alveolus \v ^Alveolus •

Fig. 8. Wasted venti­ latory volume and tidal volume. (A) Shaded 200 Zone =• wasted venti­ latory volume (VD) of airways. Dotted line 190 indicates the decrease in air space and air­ way volume with 180 rapid, shallow breath­ ing. B. Wasted ven­ tilatory volume (VD) 170 in ml on ordinate. Tidal Volume (VT) in ml. on the abscissa. 160 Note that as the tidal volume is decreased from 600 ml to 200 ml, the fraction wasted 200 400 600 increases from 1/3 to 8/10. to a right-to-left shunt in the heart and may duction of hypoxemia.29 If pulmonary blood be called a "shunt-like" effect.28 A very severe flow increases, e.g., during exercise, through a diffusion defect * may play a role in the pro­ restricted capillary bed, there may not be enough time for transfer of 02 from the air spaces to the red cells and the 02 pressure * DlCO must be less than 50 per cent of predicted to and content of the blood leaving the lung may cause hypoxemia during exercise; less than 30 per cent of predicted to cause hypoxemia at rest. be abnormally decreased.

Volume 48 / Number 5 463 | RESTRICTIVE LUNG DISEASE HYPERCAPNEA (INCREASED ARTERIAL PCO2)

Finally, in the terminal patient, the loss of lung volume and the increase in wasted ventila­ Decreased Alveolar Ventilation tion may be so great that adequate alveolar ventilation cannot be maintained relative to Decreased CO2 Elimination the metabolic needs of the body. This situa­ tion, which develops infrequently in the patient with restrictive lung disease in the terminal Increased PCOo'Airspaces phase, causes a decrease in Oo pressure and an increase in COo pressure in the arterial Increased PCO2 Arterial Blood blood (Fig. 9). Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 Acidosis. When lung function becomes very abnormal, acidosis (increased hydrogen ion Fig. 9. The cause of hypercapnea. concentration or decreased pH) may develop. If hypoxemia is so severe that tissue causes the cells to depend on anaerobic meta­ bolic pathways for energy production, lactic acid and similar compounds may accumulate ACIDOSIS in the blood (Fig. 10) causing a metabolic acidosis. If alveolar hypoventilation develops, 1. Severe Tissue Hypoxia accumulation of C02 in the blood in the form of carbonic acid causes a respiratory acidosis Decreased pOo as well. i Cells Pulmonary Vascular Obstruction i The capacity of the Lactic Acid, etc. to conduct blood becomes limited in two ways: ^ + (1) anatomic decrease in the size of the vas­ Increased H cular bed, and (2) functional decrease in the 1 size of the vascular bed (vasoconstriction). Decreased pH Of the two causes, vasoconstriction is probably quantitatively more important, especially early in the disease and therapeutically more im­ 2. Decreased Alveolar Ventilation portant since it is potentially reversible. Hypoxemia and acidosis both cause the smooth Decreased Alveolar Ventilation muscle of the pulmonary arterioles to con­ 4 30 strict. If hypoxemia and acidosis are present Increased Arterial pCO£ together, they potentiate each other; the com­ bined effect is greater than the effect of either C C02 + H20 4>H2 °3 alone. The decrease in the size of the vascular Jr bed results in an increased resistance to blood Increased Carbonic Acid flow through the lungs. To maintain pul­ monary blood flow, the heart must pump blood C with increased pressure resulting in increased 1H 2 °3 O H + HCO3 work for the right ventricle, right ventricular I hypertrophy, and finally cardiac failure. Increased H1" Concentration

Summary Fig. 10, The causes of acidosis. Restrictive lung disease is defined by a loss of lung volume usually associated with a loss of lung distensibility (Fig. 11). The process is distributed unevenly throughout the lung so that both ventilation and perfusion become

464 PHYSICAL THERAPY RESTRICTIVE LUNG DISEASE

Distensibility Anatomic I Lung Volume Vascular Bed

Unevenes:

Ventilation/Perfusion No Ventilation/Perfusion Ventilation^Perfusion Diffusing Capacity

Wasted Ventilation Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021

Alveolar Ventilation

\inctional^^Vascular Bed

Fig. 11. Restrictive lung disease: summary.

unevenly distributed. The loss of surface, the The pathogenesis of this symptom is unknown, alterations in the physiochemical properties of but it is tempting to relate it to the change in the membrane, and the loss of pulmonary lung distensibility. In addition, these patients capillaries may produce a diffusion defect. All often complain of vague chest pains and gen­ of these abnormalities may result in profound eralized fatigue. They may also have an irri­ alterations in gas exchange with hypoxemia, tating, nonproductive . initially apparent during effort, but later at Physical examination usually reveals few rest. These patients breath shallowly and abnormalities in contrast to the patient with rapidly and often in excess of their metabolic . Careful observation may needs. Finally, hypoxic vasoconstriction plus reveal rapid, shallow breathing, decreased anatomic loss of pulmonary blood vessels re­ chest expansion, clubbing; cyanosis (at first sult in pulmonary vascular obstruction. with exertion, later at rest); "dry" rales, and finally, signs of cardiopulmonary failure. CLINICAL SYMPTOMS AND SIGNS Treatment The most important symptom of patients The physical therapist who treats patients with pulmonary restriction is effort dyspnea, with restrictive lung disease has greatest re­ which ultimately occurs at rest (see Table 3). sponsibility with patients with disorders of the chest wall and restrictive complications of air­ way obstruction, such as atelectasis. The goal of physical therapy should be to prevent fur­ TABLE 3 ther deterioration of lung function by vigorous CLINICAL FEATURES treatment of complications such as bronchitis, , and pneumonia. In a few I. Symptoms A. Dyspnea patients specific treatment is available. A B. Pain patient with an occupational "dust" disease C. Cough such as silicosis should avoid further exposure. D. Fatigue Unfortunately, the pulmonary disease caused II. Signs by silicosis does not usually manifest itself A. Rapid, shallow breathing B. Decreased chest expansion until years after the initial exposure. A patient C. "Dry" rales with a granulomatous infiltrate resulting from D. Clubbing an infection such as tuberculosis should have E. Cyanosis specific chemotherapy, e.g., isoniazid. F. Cardiopulmonary failure In many patients, no such specific treatment

Volume 48 / Number 5 465 TABLE 4 the lung. W. B. Saunders Co., Philadelphia, 1964, TREATMENT pp. 350-351. 10. Colp, C. R., S. S. Park, and M. H. Williams, Jr., Pul­ I. Specific monary function studies in pneumonia. Amer. Rev. Resp. Dis., 85:808-815, 1962. A. Physical therapy 11.Berven, H., Studies on the cardiopulmonary function B. Chemotherapy of infection in the post-infectious phase of "atypical" pneumonia. C. Steroids Acta Med. Scand., 172:Suppl. 382, 1962. D. Immunosuppressive agents 12. Svanborg, N. (editor): Studies on the cardiopulmonary II. Supportive function in sarcoidosis. Acta Med. Scand. Suppl. 366, A. Physical Therapy 1961; and Stockholm, Trycheriaktiebolaget, 1961. B. Respiratory failure 13. Becklake, M., L. duPreez, and W. Lutz, Lung function in silicosis of the Witwatersrand gold miner. Amer. 1. 0 2 Rev. Tuberc., 77:400-412, 1958. 2. Assisted ventilation 14. Gaensler, E. A., L. Hoffman, and M. F. Elliott, 3. Airway Troubles de la diffusion en fibrose interstitielle dans III. Cardiac failure la silicose. Poumon et la Coeur., 16:1137-1138, 1960. Downloaded from https://academic.oup.com/ptj/article/48/5/455/4638136 by guest on 29 September 2021 15. Turino, G. M., R. V. Lourenso, L. A. G. Davidson, and A. P. Fishman, The in pa­ tients with reduced pulmonary distensibility. In: Nahas, G. G. (editor): Regulation of Respiration, Part V. Ann. N.Y. Acad. Sci., 109:932-955, 1963. 16. Gold, W. M., and D. Jennings, Pulmonary function in patients with systemic lupus erythematosus. Amer. | RESTRICTIVE LUNG DISEASE Rev. Resp. Dis., 93:556-567, 1966. 17. Berglund, E., B. Simonsson, and G. Birath, Effect of induced pneumothorax on the pulmonary shunt and is yet available. Two classes of drugs are the ventilation in a patient with atelectasis of the lung. Amer. J. Med., 31:959-965, 1961. often used—(1) corticosteroids, e.g., predni­ 18. Wohl, M. Respiratory problems associated with chest sone, and (2) cytoxic drugs, e.g., immuran— wall abnormalities. Phys. Ther., 48:467-471, May 1968. to suppress the inflamatory process present in 19. Wohl, M. Atelectasis. Phys. Ther., 48:472-477, May patients with sarcoidosis or diffuse interstitial 1968. fibrosis. In many patients subjected to this 20. Macklem, P. T., and M. R. Becklake, The relationship between the mechanical and diffusing properties of the treatment, the results have been discouraging; lung in health and disease. Amer. Rev. Resp. Dis., in a few, dramatic amelioration of the disease 87:47-56, 1960. has occurred.31 21. Read, J., and R. S. Williams, Pulmonary ventilation. Blood flow relationships in interstitial disease of the Obviously, when the process causes pulmon­ lungs. Amer. J. Med., 27:545-550, 1959. ary failure, supportive therapy (increased 02 22. Holland, R. A. B., Physiologic dead space in the concentration of inspired gas or assisted ven­ Hamman-Rich syndrome. Physiologic and clinical im­ plications. Amer. J. Med., 28:61-68, 1960. tilation) may be indicated. If cardiac failure 23. Marks, A., D. W. Cugell, J. B. Cadigan, and E. A. occurs, digitalis and diuretics may be helpful. Gaensler, Clinical determination of the diffusing ca­ pacity of the lungs; comparison of methods in normal subjects and patients with "alveolar-capillary block" REFERENCES syndrome. Amer. J. Med., 22:51-63, 1957. 1. de F. Baldwin, E., A. Cournand, and D. Richards, Jr., 24. McNeill, R. S., J. Rankin, and R. E. Forster, The Pulmonary insufficiency. II. A study of thirty-nine cases diffusing capacity of the pulmonary membrane and the of . Medicine, 28:1-25, 1949. pulmonary capillary blood volume in cardiopulmonary 2. Herbert, J. A., B. Nahmias, E. Gaensler, and E. disease. Clin. Sci., 17:465-482, 1958. Mac Mahon, Pathophysiology of interstitial pulmonary 25. Bates, D. V., C. J. Varvis, R. E. Donevan, and R. V. fibrosis. Arch. Intern. Med., 110:629-648, 1962. Christie, Variations in the pulmonary capillary blood 3. Bergofsky, E. H., G. M. Turino, and A. P. Fishman, volume and membrane diffusion capacity in health and Cardiorespiratory failure in kyphoscoliosis. Medicine, disease. J. Clin. Invest., 39:39-48, 1966. 38:263-317, 1959. 26. Mcllroy, M. B., J. Butler, and T. N. Finley, Effects 4. Kilburn, K. H., J. T. Eagan, H. D. Silker, and A. Key- of chest compression on reflex ventilation drive and man, Cardiopulmonary insufficiency in myotonic and pulmonary function. J. Appl. Physiol., 17:701-708, progressive muscular dystrophy. New Eng. J. Med., 1962. 261:1089-1096, 1959. 27. Finley, T. N., E. W. Swenson, and J. H. Comroe, Jr., 5. Christie, R. V., and C. A. Mcintosh, The lung volume The cause of arterial hypoxemia at rest in patients and respiratory exchange after pneumothorax. Quart. with "Alveolar-capillary block syndrome." J. Clin. J. Med., 5:445, 1936. Invest., 41:618-622, 1962. 6. Cournand, A., and F. B. Berry, The effect of pneu­ 28. Said, S. I., W. T. Thompson, Jr., J. L. Patterson, Jr., monectomy on cardiopulmonary function in adult pa­ and D. L. Brummer, Shunting effect of extreme im­ tients. Ann. Surg., 116:532-552, 1942. pairment of pulmonary diffusion. Bull. Johns Hopkins 7. Lester, C. W., A. Cournand, and R. L. Riley, Pulmo­ Hosp., 107:255-271, 1960. nary function after pneumonectomy in children. J. 29. Staub, N. G., Alveolar-arterial oxygen tension gradient Thorac. Surg., 11:529—553, 1942. due to diffusion. J. Appl. Physiol., 18:673-680, 1963. 8. Rossier, P. H., Les 6preuves functionnelles respira- 30. Rudolph, A., and S. Yuan, Response of the pulmonary toires pr6-operatoires des cancers bronchiques primitifs. vasculature to hypoxia and H+ ion concentration Bronches, 12:473, 1962. changes. J. Clin. Invest., 45:399-411, 1966. 9. Bates, D. V., and R. V. Christie, Respiratory Function 31.Scadding, J. G., Chronic diffuse interstitial fibrosis of in Disease; an introduction to the integrated study of the lungs. Brit. Med. J., 1:443-450, 1960.

466 PHYSICAL THERAPY