EDITORIAL
ARE CHILDREN MINIATURE ADULTS?
Children are growing and maturing beings that differ from adults, particularly with regard to the following aspects: Growth and morphological changes, immune system immaturity, organic immaturity, sexual maturation, childhood pathology, age-specific diagnostic methods, variations in therapeutic regimen and dosage by age, weight, body surface, and finally the psychological characteristics of a developing person.
Growth and morphological changes are responsible for major differences between children and adults. From the birth until that child reaches the full height, he experiences a series of morphological changes that modify the proportions of the body segments (head, chest, abdomen, limbs). Many factors are implicated in growth and it is important to be familiar with the characteristics of growth at every age and with the most suitable methods for evaluating the factors related with growth.
Immune system immaturity is a differential factor that explains why children suffer more infections and allergic diseases than adults. The immune system of the newborn differs from that of the adult. In order to attain the characteristics of the adult immune system, the body''s defense system undergoes a series of changes in the cellular and humoral immune systems, and, to a lesser degree, in non-specific mechanisms. The most notable feature of the newborn immune system is the almost complete absence of IgA and IgM antibodies and the presence of 10% more IgG than its mother. This immunoglobulin passes through the placenta thanks to an active transport mechanism. IgG antibodies transmitted by the mother protect the child for a few months, then disappear, and serum antibody levels are very low by the third month. Stimulation by contact with microorganisms causes antibody levels to rise throughout childhood. This means that children have to suffer numerous infections before they attain adult levels of protection at the age of about 10 or 12 years.
Organic immaturity affects every organ system. Digestive system immaturity facilitates the appearance of gastrointestinal infections and food allergies, and respiratory immaturity is why asthma is more frequent in children. The change from intrauterine to extrauterine life involves major structural and dynamic changes in the cardiovascular system with only a brief period for adaptation. The nervous system is particularly immature, which confers special properties on the newborn and infant. Psychomotor development advances with the maturation of the nervous system. As the nerve fiber becomes myelinized, neurological maturation and psychosocial development progress (archaic reflexes disappear, smiling and recognition of the mother appear, etc). The immaturity of the nervous system conditions special aspects of pathology, such as sensorial disturbances, convulsions, etc.
Sexual maturation is linked to the development of sex organs and secondary sexual characteristics. This stage of life, known as puberty and adolescence, is characterized by important organic and psychological changes that can originate conflicts in family, school, and social relations.
Childhood diseases. It is evident that many diseases occur only in pediatric patients and many others begin at this time of life and continue with age. However, because of the characteristics of these diseases in children, they can be considered typical of childhood. Premature birth, in itself pathological, produces manifestations that are more accentuated the in relation to the degree of prematurity. The care of premature infants requires experience, knowledge, and special hospital technology. Term newborns also suffer diseases that occur only at this time of life, such as umbilical processes or the many causes of pathological jaundice or hypoxia, to cite a few examples. The number of processes typical of newborns increases greatly when we consider the wide range of congenital malformations. Infants and pre-school children have many infections known as "childhood infections", which include the exanthematic infections. Immunological diseases also usually begin at this age and are caused by defects, such as primary immunodeficiencies, which are linked with infectious disease, and by hypersensitivity. Allergy to cow-milk proteins is typical of the first months of life and its clinical manifestations can be severe. The onset of asthma also takes place preferentially between 2 and 5 years. Accidental poisoning and foreign body ingestion also occur most commonly in small children. Injuries produced by playing, sports, and traffic accidents also occur, particularly in adolescents. Growth abnormalities and feeding disorders are other disorders typical of childhood.
Among the diagnostic methods used in pediatrics, the clinical history is noteworthy. It has to be carried out with the help of another person, generally the mother or another person close to the child, who give their own interpretation of the symptoms that they observe or believe they observe in the child. It is not uncommon that when more than one person is involved, there are discrepancies between interpretations. The pediatrician, who is aware of this, must know how to select relevant information as objectively as possible. Information of interest includes the prenatal history, birth, newborn pathology, development, vaccinations, and so on. The physical examination requires patience and skill in order to gain the child''s confidence. The physical examination per se differs greatly from that of adult patients and at different ages of childhood: for instance, it is quite different to palpate the abdomen of an infant than that of an adolescent. Many exploratory techniques require instruments adapted to the child''s size, such as endoscopes, catheters, probes or the ubiquitous stethoscope. Likewise, special techniques are used to study psychomotor development, growth or nutrition, to mention some examples.
Dosing in children is determined by age, weight and body surface. Dosage varies with age and the physician must have experience with managing dosages to ensure correct therapy. Children''s medication doses are higher than those of adults because they metabolize medications more rapidly, which may confuse persons unaccustomed to treating children. Likewise, therapeutic regimens often differ for pediatric patients because certain medications are not well tolerated or are more toxic or more effective than other medications at these ages.
A child''s psychology has special characteristics, ranging from the experience of isolation from psychosocial surroundings at birth to social integration and psychological adjustment. Adjustment problems can originate pathological states. Family psychological problems, particularly those of the mother, can cause problems that affect the health of children.
Therefore, physicians caring for children should be trained pediatric specialists who have acquired the knowledge necessary for diagnosing and treating childhood diseases using the specific skills of the specialty. Non-pediatricians who must care for children should be extremely careful in their medical interventions and remember that "Children are not miniature adults".
M. A. Martín Mateos
