Clinical medicine for nurses

Front matter

COPYRIGHT DEPOSIT.

PAUL H. RINGER, A.B., M.D.

v\

Preface To Second Edition

The general scheme of this book has in no way been altered. A goodly number of minor changes have been made, however, and some sections wholly or partially rewritten, notably those on the treatment of Heart-failure, Influenza, and Diabetes Mellitus. A short section on Auricular Fibrillation has been in¬ troduced and Eggleston’s method of full Digitaliza¬ tion of the heart has been briefly explained. The classification of nephritis has been changed, a slightly simplified modification of Christian’s excellent scheme having been adopted. Some errors have been elim¬ inated. It is hoped that no new ones have crept in.

Paul H. Ringer.

16 Haywood St.,

Asheville, N. C.

Preface To First Edition

The following chapters represent the substance of lectures on medical diseases that I have delivered for several years at the Asheville Mission Hospital.

I have been impelled to write them out, as in no text¬ book for nurses that I have seen did I feel that the subjects were taken up in sufficient detail, while in all textbooks on medicine there were far too many minutiae for the pupil nurse to attempt to master.

The object of these lectures is to place in concrete form a fairly detailed description of the points in the various diseases that nurses will be expected to ob¬ serve and interpret, and also to form a basis upon which class-room lessons can be assigned and quizzes held, the teacher amplifying as he sees fit.

It will be noted that the bacteriology and pathology of diseases, save in a very few instances, have been but sketchily traced. The main points dwelt upon have been symptoms and their meaning, complications and their detection, as far as the nurse is concerned. Physical signs have been wholly set aside. I do not feel that any nurse’s mind should be burdened with their description and significance.

Treatment has been dealt with in a general manner, it being ever borne in mind that each physician has his own preference for the treatment of almost every dis¬ ease, and that such preference should not be infringed upon in a textbook intended solely for teaching purposes

Preface

viii

by physicians with varied ideas. I do not believe that any of the principles set forth will seriously offend.

The subject matter of the lectures has no claim whatsoever to originality. I have freely consulted the best authorities at my command, abstracting here and there in order to produce a concrete whole. The only claim that these lectures have for individuality lies in their being, as far as I know, the first collec¬ tion of lectures covering a considerable number of medical diseases delivered for and to nurses.

Paul H. Ringer.

Asheville, N. C.

Contents

CHAPTER PAGE

I. Fever . 1

II. Food and Nutrition . 4

Chapter I. Fever.*

Probably the most common single symptom of acute disease is fever. It would be unwise and undesirable to go at any length into the origin of fever, for it is veiled in much mystery and in many theoretical considerations; suffice it to say that it occurs in various degrees of in¬ tensity in a host of maladies, that it is one of the best signs we have of disturbance in the human body, and that it is the one symptom above all others that by its presence speaks for the existence of some pathological condi¬ tion, though giving usually no clue to the location of the trouble.

Fever, itself, while called a “symptom,” is really a “symptom-complex,” being a very complete clinical en¬ tity, quite irrespective of the underlying cause. The ordi¬ nary symptoms of fever of moderate severity ( e.g ., 103°) are:

Hot, dry skin.

Flushed face.

Bright, anxious eyes.

Thirst.

Full, rapid and bounding pulse.

Rapid and rather shallow respiration.

Headache.

Anorexia.

General aching in body and limbs.

* Throughout this book the Fahrenheit scale is used, unless otherwise specified.

CLINICAL MEDICINE FOR NURSES.

Nausea and vomiting (not very frequently).

Constipation or diarrhea (usually the former).

Scant, high-colored urine.

Of course, at times some of these symptoms will be more intense, and at times others, but in the main all of them will be present to some extent. When the tempera¬ ture rises to 105° or over, or even below this limit in susceptible individuals, delirium may occur. This may be accompanied by convulsions, especially in children. Should the patient be extremely toxic, coma may set in —always a very serious sign.

Fever may be:

1. Continuous, e.g., scarlet fever.

2. Remittent, a fever that shows rises and falls, but

that never wholly leaves the patient, e.g., ty¬ phoid fever, septic fevers.

3. Intermittent, a fever that seizes! the patient, and

then wholly disappears, only to return again, e.g., the fever in tertian and quartan malaria.

Fever may begin:

1. Suddenly, e.g., lobar pneumonia.

2. Gradually, e.g., typhoid fever.

Fever may end:

1. By crisis, i.e., suddenly; e.g., lobar pneumonia.

2. By lysis, i.e., gradually; e.g., typhoid fever,

measles.

Fever is divided into the following classes by Wunder¬ lich :

2. Slightly febrile, 100.4° to 101.3°.

3. Moderately febrile, 101.3° to 103.1°.

4. Decidedly febrile, 103.1° to 104°.

FEVER.

5. Highly febrile, above 103.1° in the morning and

above 104.9° in the evening.

6. Hyperpyretic, above 106°.

There is usually a certain ratio between the height of the temperature and the pulse-rate. Thus, generally speaking

A temperature of 98.4 corresponds to a pulse-rate of 70 a

“ 100.

a

u u

a

“ 80- 90

it

it

“ 102.

a

“ 100-110

u

“ 104.

u

it u

a

“ 120-130

These rules are capable of the utmost variation.

Chapter II. Food And Nutrition

All food may be regarded as fuel, and the body as the furnace in which it is consumed. The object of food is to supply nutriment to the body, and this nutriment is used in the production of heat and energy. When taken into the body, food undergoes the following processes:

1. Digestion.

2. Absorption.

3. Oxidation.

4. Excretion.

6 per cent, of body weight.

There are five main classes of foodstuffs:

1. Proteins.

2. Fats.

3. Carbohydrates.

4. Mineral salts of

(w) Calcium

(*■) Sodium

(y) Potassium

(z) Magnesium

5. Water—60 per cent, of food, and serving, among

other things, to keep the body at a proper con¬ sistency.

1. Proteins. These include all foodstuffs containing nitrogen (N), and are absolutely indispensable to the maintenance of life. An animal fed on a protein-free diet, no matter how generous or how abundant it may be, eventually starves to death.

FOOD AND NUTRITION.

Proteins are divided into several sub-classes, but three of which will be mentioned:

I. Albuminoids.

(a) White of egg.

( b ) Curd of milk.

( c ) Lean of meat.

( d ) Gluten of wheat.

II. Gelatinoids.

Gelatin the best example.

III. Extractives.

Contain nitrogen, but differ from the two preceding in that they merely add zest to the food, but have practically no nutritive value.

2. Fats. Fats, roughly speaking, make up about 15 per cent, of the average individual, and are generally taken into the body in the form of:

Butter.

Cream.

Oils.

The amount of fat varies very greatly in different in¬ dividuals.

3. Carbohydrates. These substances are formed of carbon (C), hydrogen (H) and oxygen (O), the last two always appearing in the proportion to form water—H 2 0. Thus, starch has the chemical formula C 6 H 10 O 5 . It will be noted that the atoms of H are just twice as numerous as those of O; thus we have the proportion H 2 0. Bread, rice, and potato are examples of carbohydrate foods.

Object of Various Foodstuffs.

1. Proteins. These are to build up tissue, and to a cer¬ tain extent to be converted into other foodstuffs, such as

CLINICAL MEDICINE FOR NURSES.

fat and carbohydrate. They also serve as fuel to yield heat and muscular power.

2. Fats. These form an abundant source of heat and energy. They are also useful in serving as a buffer to the body at various points where much friction occurs, and in addition form the main reserve and storehouse upon which the body can make demands in times of necessity. Thus, when food is withheld, the body needs are primarily supplied by the overplus of 1 fat. The emaciation consequent upon long illness is chiefly due to the oxidation and using up of the reserve store of fat.

3. Carbohydrates. In addition to their intrinsic food value, these substances may be transformed into fats, and used as such, or else they may be used as fuel to supply the immediate body needs.

As mentioned above, protein is the substance without which life cannot be sustained. Protein can, to a certain extent, be transformed into fat and carbohydrate, and, as seen above, carbohydrate can be transformed into fat; but neither fat nor carbohydrate can in any way be trans¬ formed into protein, for neither of them contains the all-important element, nitrogen. Hence, a protein-free diet amounts in the long run to starvation, and, if per¬ sisted in for a sufficient length of time, proves fatal.

From the foregoing it must not be imagined that a fat-free or a carbohydrate-free diet would in any way prove nourishing, beneficial or healthful. All three classes of foodstuffs are of paramount importance to the human body, and must be taken in certain well-defined general proportions; but stress must be laid on the fact that protein is an absolute necessity.

The energy and heat of the body are derived from the combustion of its foodstuffs. As energy can be con-

FOOD AND NUTRITION.

verted into heat, the value of foodstuffs can be expressed in heat units. The heat unit is called calorie. A calorie is that amount of heat needed to raise a kilogram of water to one degree Centigrade.

The amount of heat given off from the human body has been measured with accuracy. In a condition of rest, a man gives off heat in twenty-four hours equiva¬ lent to about 33 calories per kilogram (2.2 pounds) of body weight. Thus, a man weighing 70 kilos (154 pounds) gives off about 2310 calories (70 X 33). This amount must be supplied by foodstuffs in order to main¬ tain a satisfactory state of nutrition. It has been calcu¬ lated that these 2310 calories must contain about 500 Gm. of carbohydrate, 50 to 100 Gm. of fat, and 120 Gm. of protein.

1 Gm. of protein produces 4 calories.

1 Gm. of fat produces 9 calories.

1 Gm. of carbohydrate produces 4 calories.

Rubner gives the following standard dietary for a man of 70 kilos (154 lbs.):

Protein Gm.

Fat Gm.

Carbohydrate Gm, Calories .

Light

Medium

Heavy

work

work

work

.. 123

.. 46

.. 377

.. 2445

Thus it will be seen that the average man doing med¬ ium work requires about 127 Gm. of protein daily. Not much more than 150 Gm. can be given without the ap¬ pearance of symptoms of overfeeding—gastric or intes¬ tinal derangements. In feeding any individual, the point

CLINICAL MEDICINE FOR NURSES.

to be borne in mind is not so much the maximum or minimum number of calories which the patient will toler¬ ate, or upon which he can exist, as that amount upon which the patient will thrive best.

The following table gives the daily needs in calories of an adult weighing 65 kilos (162.5 lbs.) :

1. During rest in bed 1800 cal., or 28 cal. per kilo of body wt.

2. In repose

3. Light work

4. Moderate work

5. Hard work

2100 “ “ 32 “

2300 “ “ 33 “

2600 “ “ 40 “

3100 “ “ 48 “ t u a a a

% a a a a

i u a a u

» f ii m a u a

Infants require more calories per kilo of body weight than do adults. This can readily be accounted for when we consider the tremendous growth and consequent tis¬ sue changes taking place in the infant.

For 1st 3 mos. an infant requires 100 cal. per kilo of body wt.

Average cow’s milk contains 320 calories per pint (640 calories per quart). Eggs contain about 720 calories per pound, the whites alone yielding 250 calories per pound, and the yolks 1705 calories per pound. The white is pure protein, while the yolk contains numerous substances, chief of which are: 15 per cent, protein, 20 per cent, fat, besides lecithin, nuclein, salts of iron, calcium, potassium, and magnesium.

Meats are best prepared by broiling or roasting. Bouil¬ lons and beef extracts consist mainly of extractives from the meat, and, contrary to an idea, almost universally prevalent among the laity, have practically no food value. The following table gives the caloric value per pound of the principal meats:

FOOD AND NUTRITION.

Calories

Beef (steak) . 975

Veal . 745

Mutton . 890

Pork chops . 1245

Chicken (broilers) . 305

Turkey . 1060

Vegetables contain a large percentage of starch and sugar, and a somewhat lesser percentage of protein.

The number of calories needed daily by a man in health has been dwelt upon in some detail. When an individual is suffering with fever from any cause, from 20 to 30 per cent, more heat is given off than in health. This must be made good by an increased caloric intake, or the patient will suffer. Especially is this true in long fevers, such as those caused by typhoid, tuberculosis, and rheu¬ matic fever. In the shorter fevers, such as lobar pneu¬ monia, the maintenance of the bodily strength by means of increased caloric feeding is not so important. If 25 per cent, be added to the normal amount required by the average man (2300 calories in 24 hours), we see that during fever from 2800 to 2900 calories in 24 hours will be needed.

Foods whose caloric value is not very great can have that value raised by the addition of substances whose caloric value is very high, such as milk sugar (caloric value per ounce, 117) and cream (caloric value per ounce, 54). Qualitative changes can be made in foods which will counteract the enormous quantity that would have to be ingested to supply the caloric needs were the food, as such, given. For instance, if in a case of typhoid reliance were placed solely on a milk diet, and the stock order, “a glass of milk every two hours” carried into

CLINICAL MEDICINE FOR NURSES.

effect, the patient would be wretchedly under-nourished. A glass of milk contains from 6 to 8 ounces. One quart of milk produces 640 calories. Ten feedings will be about all the patient will get in 24 hours. He will, there¬ fore, be given from 60 to 80 ounces of milk—practically two quarts, 1280 calories—two-thirds of what he should really have. To meet the needs of the patient, five quarts of milk daily would be required.

Latterly, the so-called-“high-calorie diet” has been used with marked success in the treatment of typhoid fever, further reference to which will be made in the chapter on that disease.

Administration of Food to the Sick.

Details—one might almost say trivialities—are of the greatest importance, and are too often not sufficiently heeded by the nurse. Florence Nightingale wrote: “To watch for the opinions which the patient’s stomach gives rather than to read ‘analyses of foods’ is the business of all those who have to settle what the patient is to eat— perhaps the most important thing to be provided for him after the air he breathes. * * * An almost universal

error among nurses is the bulk of the food, and especially of the drinks, they offer to their patients. It requires very nice observation and care (and meets with hardly any) to determine what will not be too thick or too strong for the patient to take, while giving him no more than he is able to swallow.”

The following are some important points to be noted in the feeding of the sick:

1. Punctuality. To the invalid meal-time is an import¬ ant event. He looks forward to it with interest and with

FOOD AND NUTRITION.

curiosity. He eyes the clock a hundred times until the arrival of the appointed hour. When that hour comes, the meal also should come. Waiting until the stated time tends to sharpen the patient’s appetite; waiting beyond that time disappoints, irritates, and tends markedly to blunt the desire for food.

2. Do not ask the patient with a poor appetite what he wants to eat. He does not want anything, and if foods are named to him and his suggestions invited, his repug¬ nance becomes increased. His appetite can best be stim¬ ulated by exciting his surprise and curiosity.

3. Untasted food, dishes after use, half-emptied cups and glasses, should never be left in the sick-room. They are unsanitary, and often tend to nauseate the sensitive patient. There is nothing more frequently seen in the sick-room, and there are few things more disgusting, than an empty, unwashed glass that has contained milk.

4. Wipe dishes dry on the outside, and take special care that the contents of cups are not spilled into the saucers.

5. Mutton or chicken broth should be skimmed several times before serving. Blotting paper or a piece of thread can be passed over the surface to remove the last traces of oily substance.

6. When the dietary is limited, or the appetite is poor, it is often well to serve the meal in “courses.” Time after time the writer has had patients complain that they lost all desire for food at once after the appearance of a large tray loaded down with all sorts of eatables, from soup to dessert. Many of these same patients would have eaten well and with enjoyment had the same food been daintily served, one course at a time.

CLINICAL MEDICINE FOR NURSES.

7. Do not offer food to the patient immediately after a bowel or bladder evacuation. If the patient has just used the bed-pan or urinal, the nurse should make it very ap¬ parent that she has thoroughly cleansed her hands be¬ fore busying herself with food.

Chapter III. The Circulation—general Considerations

The vascular system in and through which the blood circulates consists of a central pump (the heart) and a system of tubes of three distinct types:

1. Arteries. Vessels carrying blood away from the heart, becoming progressively smaller as their distance from the heart increases, having walls relatively thick, rich in elastic fibres, by the recoil of which the blood stream generated by the force of the heart-beat is kept in motion, and in which the blood is kept at a relatively high degree of pressure.

2. Capillaries. Microscopic vessels everywhere per¬ meating the tissues, lined by a single layer of cells, through the walls of which the food and oxygen brought by the blood are taken up by the tissues, and the waste products to be gotten rid of by the organs of elimination are given off.

3. Veins. Relatively large vessels, in comparison with the arteries, becoming progressively larger as.they ap¬ proach the heart, bearing stale and deoxygenated blood toward the heart, having thin walls, poor in elastic fibres and easily collapsible, containing the blood under very low pressure, and possessing at frequent intervals small valves to prevent any appreciable back-flow of blood.

The circulation—regular, incessant, and rhythmic—of the blood in this closed system of tubes was first dis¬ covered and demonstrated by William Harvey in 1616. In order to better understand the meaning and causation

CLINICAL MEDICINE FOR NURSES.

of symptoms in many diseases to be dealt with later, a glance into the realm of the physiology and mechanics of the circulation is desirable.

Course of the Circulation.

Left ventricle.

Aorta.

Fig. 1.—General diagram of the circulation: the arrows indicate the course of the blood; PA, pulmonary artery; PC, pulmonary capillaries; PV, pulmonary veins; LA, left auri¬ cle; LV, left ventricle; A, systemic arteries; C, systemic cap¬ illaries; V, systemic veins; RA, right auricle; RV, right ven- - tricle. (From “Howell’s Physiology,” W. B. Saunders Co.)

Systemic arteries.

Systemic capillaries.

Systemic veins (some blood deflected through portal system; vide infra).

THE CIRCULATION.

Right auricle.

Right ventricle.

Pulmonary artery (containing venous blood), named “artery” because it carries blood away from the heart.

Pulmonary capillaries (lungs).

Pulmonary veins (4) (containing arterial blood), named “veins” because they bring blood toward the heart.

Fig. 2.—Diagram of the portal system: the arrows indi¬ cate the course of the blood; A, arterial system; V, venous system; C, capillaries of the spleen, pancreas, and alimentary canal; PV, portal vein; C", capillaries of the liver; C', the rest of the systemic capillaries. The hepatic artery is not represented. (From “Howell’s Physiology,” W. B. Saunders Co.)

Left auricle.

Left ventricle.

Subdivisions of the Circulation.

1. Greater or systemic. Includes all arteries, capil¬ laries and veins throughout the body, except those going to and from the lungs and those vessels uniting to form the portal system ( q.v .).

CLINICAL MEDICINE FOR NURSES.

2. Lesser or pulmonary. Includes the pulmonary ar¬ tery, the pulmonary capillaries and the four pulmonary veins—in other words, all those vessels in which the blood is contained from the time it leaves the right ven¬ tricle until it enters the left auricle.

3. Portal or splanchnic. Includes those veins (and veins only) which drain the alimentary tract, and whose blood, consequently, is more filled with waste products than is that from other portions of the body. These veins—the so-called “radicals”—of the portal system join to form the portal vein which, in company with the hepatic artery and the common bile duct, enters the liver embedded in the capsule of Glisson, and iii the liver breaks up into branches, and delivers its blood to that organ to be further purified before leaving through the hepatic vein to proceed onward toward the heart.

The physiology of the circulation, especially that of the lesser or pulmonary circulation, is so intimately blended with the fundamentals of the physiology of respiration that a few lines on that subject will not be amiss.

Respiration and the lungs provide for an exchange of gases between the blood on the one hand and the external air on the other. The blood coming to the pulmonary capillaries from the right side of the heart via the pul¬ monary artery, is blood that has made its rounds of the circulation, has given up to the tissues the oxygen that it had acquired at its previous passage through the lungs, and has taken unto itself instead waste products ab¬ sorbed from the tissues during its passage through them. It must now yield up its waste products, and take unto itself a new supply of oxygen. This can be done in the pulmonary capillaries. These microscopical vessels have walls of extreme thinness, and through the single layer

THE CIRCULATION.

of endothelial cells forming these walls the interchange of gases takes place during the few seconds that any given red blood corpuscle is flowing through the lungs.

The blood corpuscle gives off carbon dioxide (C0 2 ), and in exchange receives a full charge of oxygen from the air inspired during its sojourn in the lungs. Re¬ freshed and ready for its duty, the corpuscle is then car¬ ried by the pulmonary veins to the left side of the heart, whence it is started on its trip over the body to give up in turn to the needy tissues the oxygen without which they cannot live.

The air in the alveoli or terminal chambers of the lungs is kept fresh and ever changing by the respiratory move¬ ments, pure air, rich in oxygen being inspired, and stale air being expired.

The Heart. The heart, or central pump, power-house and motive force of the entire circulatory system, de¬ mands notice. It is composed of muscle, striated, but involuntary—that is to say, possessing the striae common to voluntary muscles, but being quite beyond the power of the will, though most susceptible to the emotions.

The heart contains four cavities or chambers. The two upper and smaller ones are the auricles, right and left, respectively. The two lower and larger ones are the ventricles, also right and left, respectively. The right auricle opens directly into the right ventricle, and the left auricle into the left ventricle. The superior and in¬ ferior venae cavae open into the right auricle. The pul¬ monary artery opens out from the right ventricle. The four pulmonary veins, two from each lung, open into the left auricle. The left auricle empties directly into the left ventricle; and the aorta, the main arterial trunk of the body, emerges from the upper part of that chamber.

CLINICAL MEDICINE FOR NURSES.

The Cardiac Cycle. From the beginning of one beat of the heart to the beginning of the next succeeding beat constitutes a “cardiac cycle.” The cardiac cycle is divided into two main parts:

1. Systole —the work portion of the cycle—that por¬ tion during which the auricles and ventricles contract and drive the blood onward.

2. Diastole —the rest portion of the cycle—that por¬ tion during which the cavities of the heart are being filled with blood which will be forced onward at the next systole.

The contractions of auricles and ventricles do not take place at exactly the same time, the auricles contracting immediately before the ventricles.

The ordinary complete cardiac cycle with the heart beating 72 times to the minute, lasts eight-tenths of a second. Of this:

( 4 :) Auricular systole lasts 0.1 second.

(y) Ventricular systole lasts 0.3 second.

(£) Diastole lasts 0.4 second.

Thus it is seen that 50 per cent, of the time is spent by the heart in resting. When we consider that from birth to death the heart never has what in the ordinary sense we construe as “rest,” the importance of this recupera¬ tive portion of the cardiac cycle is at once apparent.

The vagus nerve exercises an important inhibitory or slowing effect upon the heart. It acts as a brake, and prevents the heart from running away with itself. Thus, it is another potent factor established by Nature for ensuring the heart’s obtaining enough rest.

The Cardiac Valves. With this multiplicity of car¬ diac chambers and of vessels entering and leaving these chambers, there exists a most simple and unique means

THE CIRCULATION.

of preventing the back-flow of blood, and of maintaining the mechanics of the circulation. This unique means con¬ sists in the valves of the heart. The valves of the heart are four in number:

1. Mitral or bicuspid valve, situated between the left auricle and the left ventricle, opened automatically by the blood current during ventricular diastole, and similarly closed during ventricular systole, thus preventing regur¬ gitation of blood into the left auricle, and causing all the blood in the ventricular cavity to be discharged through the aorta and thus to reach the body generally.

2 . Tricuspid valve, situated between the right auricle and the right ventricle, opened automatically by the blood current during ventricular diastole, and similarly closed during ventricular systole, thus preventing regurgitation of blood into the right auricle, and causing all the blood in the ventricular cavity to be discharged through the pulmonary artery, and thus to reach the lungs.

It will thus be seen that the mitral and tricuspid valves open and close at the same time and act similarly, the former on the left and the latter on the right side of the heart. This also applies to the two sets of valves next to be considered.

3. Aortic semilunar valves, situated at the emergence of the aorta from the left ventricle, automatically closed by the reflux of blood after ventricular systole, and re¬ maining closed during ventricular diastole, thus prevent¬ ing regurgitation of blood into the ventricular cavity, which is being filled anew from the left auricle; auto¬ matically opened by the blood current during ventricular systole to allow the passage of blood into the aorta.

4. Pulmonary semilunar valves, situated at the emer¬ gence of the pulmonary artery from the right ventricle,

CLINICAL MEDICINE FOR NURSES.

automatically closed by the reflux of blood in the pul¬ monary artery after ventricular systole, and remaining closed during ventricular diastole, thus preventing re¬ gurgitation of blood into the ventricular cavity, which is being filled anew from the right auricle; automatically opened by the blood current during ventricular systole to allow the passage of blood into the pulmonary artery.

All the valves have three cusps or flaps save the mitral, which has but two. The flaps on the tricuspid and mit¬ ral valves are large and somewhat fan-shaped, of rather thick, fibrous structure, and covered with a glistening membrane, the endocardium, which is continuous with that lining the ventricular cavity. These cusps are con¬ nected with the ventricular walls by fine, cord-like proc¬ esses, the chordae tendince, and do not move freely in the blood current.

The structure of the aortic and pulmonary semilunar valves is precisely similar. Both are composed of three flaps, each the shape of a half-moon, these three cusps meeting in the center of the lumen or calibre of the ves¬ sel when the valve is closed, and lying up against its wall when the valve is open. They are of much finer structure than are the auriculo-ventricular valves, are about the thickness of a piece of ordinary writing paper, translucent, and lined on their cardiac surfaces with a continuation of the endocardium that lines the ventric¬ ular cavity.

These few physiological and anatomical facts will en¬ able us to better approach the clinical side of diseases and disturbances of the heart and circulatory system.

Chapter IV. Rheumatic Fever

Rheumatic fever has all the ear-marks of an acute infectious disease caused by a specific micro-organism. Hitherto the particular germ has resisted discovery, so the fundamental causative factor is not known. It is believed, however, to be a form of streptococcus. Rheumatic fever is intimately associated with the various diseases of the heart, to be taken up shortly. Dr. Olchin, a celebrated English clinician, has said that in adults rheumatic fever is a disease of the joints, with heart symptoms secondary, while in children rheumatic fever is a disease of the heart, with joint symptoms secondary. In any event, the connection between rheu¬ matic fever and pericarditis, endocarditis, and myocar¬ ditis is so close that it is the heart that must be watched first, last, and all the time.