Elements of pediatrics for medical students

Preface

The study of Pediatrics has developed rapidly and has not yet assumed a reasonable or logical form. The fact that infants differ from adults in various points of anatomy, physiology, pathology, diagnosis and treatment is too little appreciated, so that works on pediatrics are still published which are devoted almost entirely to the diseases of infants and children with little or no information regarding the characteristics of children or of that part of pediatrics which occupies a large portion of the time of most pediatrists, the problem of keeping infants and children well by proper regime and feedings.

It is the aim of this book to impart these facts in a simple and concise form, and in addition to summarise the important facts to be obtained by physical examination, by examination of the urine and feces and by Roentgen-ray examination and review briefly the essentials of diagnosis and treatment. The author believes that the information it contains is of the sort that should be made familiar to medical students before they take up the study of the diseases of infancy and childhood.

The author wishes to express his indebtedness to Professor William Perry Northrup, to Professor Edwin Bradford Cragin, to Professor Francis Carter Wood, and to Doctor Oscar M. Schloss for valuable

PEEFACE

suggestions ; also to Doctor Anthony C. Freeman for aid in preparing the Chapters on "Urinary Analysis/ ' and "Examination of the Feces"; and to Miss Nina A. Brown for the preparation of the illustrations, proofreading and the making of the index.

Table Of Contents

CHAPTER PAGE

I Anatomy of the New Born 1

II Physiology of the New Born 12

Chapter I Anatomy Of The New Bokn

Characteristics of infant. — On examining a healthy infant, having in mind the adult type, one is immediately impressed with certain marked characteristics. (Figure No. 1.) The infant has a very large head and a small face, and apparently, although not really, a short neck, a rather small thorax in contrast with a large protruding abdomen, a very slightly developed pelvis and small legs. For an explanation of these peculiarities, which are most marked at birth, one has to consider the nourishment of the child in utero.

l

Infant at Birth Adult

Comparison of Infant at Birth

with Adult.

Foetal circulation. — The foetus in utero is supplied with oxygen, as well as nourishment, from the placenta by means of the circulation of its blood through the placenta, where it obtains from the blood of the mother the nourishment it requires. (Figure 2.)

The vessels that carry the blood of the f cetus to and from the placenta are three: the two umbilical arteries carry blood to the placenta ; while the umbilical vein passes from the placenta along the umbilical cord, carrying this fresh placental blood to the liver, where it divides into three branches, two of these supplying the liver, while the third, the ductus venosus, carries the blood to the inferior vena cava and thus to the right auricle of the heart. Here it does not pass into the right ventricle, as in the adult, but by means of the Eustachian valve this blood current is directed through the foramen ovale to the left auricle, from which it flows into the left ventricle, being forced from there into the aorta. This placental blood, then, is supplied to the liver and to the head and upper extremities by means of the aorta, while before it reaches the descending aorta, it is mixed with blood from the right side of the heart.

The portion of this blood which passes through the carotid and subclavian arteries to the head and upper extremities returns to the superior vena cava, passes into the right auricle and right ventricle, and is forced by the contractions of the ventricle into the pulmonary arteries, from which by means of the ductus arteriosus a considerable portion of it passes into the descending aorta, reaching, through the in-

Diagram of the Circulation of the Foetus Indicating the Parts that Disappear After Birth.

A. Umbilical Vein.

D. Foramen Ovale.

B. Ductus Venosus. C. Eustachian Valve.

E. Ductus Arteriosus. F. Umbilical Arteries.

ternal iliac and umbilical arteries, the umbilical cord and placenta.

Respiration. — During the period of intra-uterine life, then, the lungs are solid organs ; and the heart has the Eustachian valve and the opening of the foramen ovale between the auricles. It is thus evident that at birth very radical changes must take place in order that the infant may still obtain the necessities for life. The placental nourishment is cut off and the child gasps for breath. This air passes through the mouth, pharynx, larynx, and bronchi, and must be drawn into the lung, at this time practically a solid organ. With many infants breathing is at first difficult and insufficient, and only after considerable assistance through counter-irritation, the application of heat or cold, or the use of artificial respiration, is a sufficient function of the lungs established.

Changes in the heart after birth. — With the establishment of the function of the lungs the usefulness of the foetal appendages of the heart is passed, so that the Eustachian valve disappears, the foramen ovale gradually closes, the ductus venosus becomes a fibrous cord in from four to ten days, the umbilical vein becomes the round ligament of the liver in from two to five days, while the umbilical arteries form the anterior true ligaments of the bladder. A study of the foetal circulation, then, shows us one reason why the moment of birth is a critical moment for the infant ; why some parts of the body, such as the head and liver, receiving a better blood supply, should become more developed during intra-uterine life than

ANATOMY OF THE NEW BORN 5

others, and it also shows us the direction that will be taken by navel infections in infancy; in such cases the umbilical vein is sometimes found rilled with pus.

Proportions of infant body in comparison to adult. — As will be seen by reference to the chart (Figure 1) the large head of the infant occupies about one-fourth of its stature, while in the adult the line dividing off the upper fourth of the body passes through the axillary line, and the head occupies about one-eighth of the stature. Again the middle line of the body which in the child at birth passes just above the umbilicus, in the adult is much lower, at about the level of the crest of the ilium. The trunk, Dr. Rotch has well said, resembles somewhat the shape of an egg; the large end of the egg represents the lower part of the body, the shoulders being attached to the smaller end.

Appearance. — Healthy babies at birth should have a bright red color and should be plump with a fairly thick layer of adipose tissue below the skin.

Sebaceous glands. — The sebaceous glands of the skin are well developed at birth and this is evident from the large amount of vernix caseosa, the excretion of these glands, which is often found on the body of the child at birth.

Sweat glands. — The sweat glands are not well developed.

Weight. — These stocky little bodies should weigh about seven pounds at birth, but this weight may vary from six to nine pounds or more, depending on the

6 ELEMENTS fOF PEDIATEICS

length of the body and the state of nourishment, these conditions again depending on the size and health of the parents and the duration of intra-uterine life.

Length. — The length of the body should be about twenty inches; the circumference of the head thirteen and one-half inches, that of the thorax thirteen, and that of the abdomen about fourteen inches. This latter measurement is very variable, depending to a considerable extent on the distention of the intestines with gas at the time the measurement is taken.

Navel wound. — One of the greatest dangers to the infant is its first wound, the severed cord, which if allowed to remain moist or if contaminated by an invasion of bacteria may lead to an infection which sometimes speedily ends life. The navel should be healed in about five days.

Skeleton. — The skeleton of these babies is very incompletely developed.

Skull. — The bones of the skull have not united so that during birth they are pressed together and often overlap. Four considerable openings exist, diminishing in size in the order named : the anterior f ontanelle (Figure 14), the largest, is at the junction of the frontal and parietal bone and is usually about an inch in lateral diameter and two inches in longitudinal diameter; the posterior fontanelle, at the junction of the occipital bone with the two parietal bones in the median line at the back of the head is usually sufficiently open to be felt, as are also the two lateral fontanelles at the junction of the occipital, parietal

ANATOMY OF THE NEW BOEN 7

and temporal bones, and so long as the sign known as cranio-tabes — the depression of the bones of the skull over the lateral f ontanelle on pressure by the fingers — is present it may be assumed that this closure is not complete. When one considers the very deficient ossification of the skull and the fact that the two frontal bones are never completely united, that the frontal and parietal, parietal and temporal, and the parietal and occipital, as well as the two parietal bones have no bony connection, being joined by membrane only, it is evident that the brain is but slightly protected, and that the skull may easily be unduly compressed by tight bandaging or its shape altered if the child is allowed to lie continuously on one side.

Spinal column. — The spinal column is largely cartilaginous and very flexible, so that when cut away from the ribs it may readily be bent in all directions. It, moreover, has but one curve with its convexity backward. Thus abnormal curvatures may result from fairly slight causes.

Head. — We have noticed that the head of the child is very large, in fact, occupying one-fourth the length of the body instead of one-eighth as in the adult, and this is due to the large size of the brain, which often weighs three-fourths of a pound, that is one-ninth of the total weight of the child. It is thus five times as large in proportion to the body weight as in the adult. The dura mater is quite adherent to the bone.

The face. — The face of the infant at birth is very small, being only one-eighth as large as the cranium and this small size is due to the fact that the nose and alveolar process of the maxillary bones are but little developed. The walls of the cheeks are thickened by large pads of fat, which render them more resistant and thus of service in sucking.

Nasal cavity. — The nasal cavity is small, particularly the post-nares, so that this is easily occluded by inflammatory processes. Moreover, in this postnasal pharynx there exists a mass of lymphoid tissue known as the third tonsil or adenoid, which is of considerable importance in children, because in certain climates it very commonly becomes enlarged, giving rise to symptoms, often very early in life, which if persistent necessitate its removal.

The mouth. — The mouth is somewhat drier than in adults, due to the slight development of the salivary glands, and the tongue is proportionately smaller. While no teeth are to be seen, the twenty teeth of the first set are present in the sacs of the alveolar process of the superior and inferior maxillary bones. These are covered by mucous membrane and do not usually begin to pierce this membrane until after the sixth month.

The eye. — The eye at birth is a perfect organ, the poor perception of these infants being due probably to insufficient brain development. The lachrymal glands are inactive, so that when these young babies cry they shed no tears. The orbital plate of the frontal bone is very thin, offering little resistance to foreign bodies brought in contact with it.

ANATOMY OF THE NEW BOEN 9

The ears. — The ears at birth are in part well developed, but the mastoid cells are not well developed until after puberty, although inflammation of the mastoid often occurs in early life.

The neck. — The neck of the child is really proportionately longer than in adults, the apparent shortness being due to adipose tissue under the chin and above the clavicle. Between the muscles of the neck there are a large number of lymph nodes which, though rarely noticeable at birth, are often the seat of enlargement in babies and young children.

Thymus gland. — The thymus gland, which is situated behind the upper part of the sternum, often coming down well over the pericardium, is a conspicuous organ at this period and important because children in whom it is enlarged seem particularly liable to sudden death, this enlargement being associated with the condition known as lymphatic constitution.

The heart. — The heart of the baby at birth is proportionately somewhat larger than in the adult and occupies a considerable portion of the thoracic cavity, its weight being about six drachms.

The lungs. — The lungs, even when well aerated, differ materially from the adult lungs. The bronchi are larger and more numerous; the air cells are much smaller; the interstitial tissue much more abundant. These facts are important in connection with the respiratory diseases of infants and young children, which differ in type from those found in adults. The pneumonia of infants is usually broncho-pneumonia instead of lobar pneumonia, which commonly occurs in adults.

The diaphragm. — The diaphragm, which plays a comparatively more important part in respiration in babies than in adults, is well developed and occupies a higher position.

The abdomen. — The abdomen is prominent in babies, owing to the large size of the liver, as well as to the small size of the pelvis.

The liver. — The liver, as already stated, is very large, weighing about three ounces six drachms, or nearly one-fourth of a pound, that is one-twentyeighth as much as the body weight instead of onethirty-seventh as in the adult ; it contains much more fat than is contained in the liver of adults.

The kidneys. — The kidneys also are of a relatively large size and frequently contain infarctions of uric acid, which cause red stains on the diapers.

The bladder. — The bladder owing to the small size of the pelvis, is in the new born an abdominal organ, and when distended is readily palpable.

Stomach and intestines. — The stomach and intestines vary in form and position from that of the adult, these variations being due to the type from which they are developed. In early fetal life the alimentary tract is a straight tube which, with growth in length, becomes doubled upon itself. Thus, the stomach, as would be expected, occupies a more vertical position than in the adult and is more tubular, the fundus of the stomach being but slightly developed. The caecum is in infancy very movable, and

ANATOMY OF THE NEW BORN 11

the appendix may be found in an infant at birth anywhere between the liver and the region of the rectum, although usually it is found in the right iliac fossa.

Weight of viscera. — In Figure 16 is shown the weight of the principal viscera at birth and to the fourteenth year. All the viscera are heavier at birth in proportion to the weight of the body than in adults. This is most marked in the brain which in infants is more than one-tenth of the body weight, while in adults it is about one-fiftieth. Next in order comes the liver, the kidneys, the heart, while the lungs and spleen are only slightly heavier in proportion to the body weight than in the adult.

Chapter II Physiology Of The New Born"

Vitality. — New born babies exhibit a degree of vitality which is somewhat proportionate to their weight. A well developed child of fair weight who is properly managed from birth usually gives little trouble.

A baby of four or five pounds has very poor vitality and needs special treatment; a baby of seven pounds has normal vitality; while one of eight or nine pounds has a high degree of vitality.

As soon as a new born child has established a good respiratory function, it should become quiet and sleepy. It should sleep practically all the time except when being fed; any deviation from this condition is an evidence of some abnormality. Although the eyes may open and close, the vision apparently makes little impression on the brain. When uncomfortable the infant will cry out.

The rectal temperature is normally about ninety-nine degrees Fahrenheit; the pulse varies from one hundred and twenty to one hundred and forty, while the respirations are rather rapid, varying from forty to sixty or seventy per minute. The respirations are also very irregular, the child breathing quickly for a time and then again slowly. The

PHYSIOLOGY OF THE NEW BOEN 13

normal relation of respirations to pulse of one to four is not present in the new born but is established soon after birth.

Salivary glands. — The salivary glands of the new-born, as has already been stated, produce but little secretion. This, however, has power to decompose starch. The secretion is increased after the second month and markedly so after teething.

Digestion. — The stomach takes but little part in digestion of food in the infant, but provides a reservoir into which the milk is received and from which it passes quickly into the intestines. Pepsin is, however, found in the stomach at birth, as is free hydrochloric acid ; a fat splitting ferment is also said to be present. Protein is transformed into acid albumin, albuminose and peptone.

Pancreas. — The pancreas is fairly developed, but its secretion probably has little amylolytic action.

Bile — Meconium. — Bile and bile salts are secreted and pass into the intestines during intra-uterine life, and these, together with desquamated epithelium and other material, form the meconium which is contained in the intestines at birth and which is gradually expelled during the first day or two of life. The total amount of this meconium contained in the intestine at birth is two or three ounces.

Urine. — The activity of the kidneys begins at birth. The amount of urine secreted during the first two days of life is small and the urine has a high specific gravity of about 1015 to 1020.

Blood. — The blood of the new born shows variations from the adult type. It contains about six million red blood corpuscles in each cubic millimeter while the white corpuscles are proportionately much more numerous during the first two days than in the adult, being about eighteen thousand to the cubic millimeter, but after the third day they are about the normal adult number.

The haemoglobin is very high during the first week. It gradually drops from 23 grams per 100 c.c. of blood, so that by the latter part of the first year it reaches only 12-13 grams per 100 c.c. of blood, it then gradually increases until about the fifteenth year when it is about 16 grams per 100 c.c. of blood at which amount it continues during adult life.