Peculiarities of Pediatric Surgical Patient

8/13/2019 Peculiarities of Pediatric Surgical Patient

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Peculiarities

of pediatric surgical patient

Nicolae Testemitanu State Medical and Pharmaceutical University

Department of Pediatric Surgery, Orthopedics and Anesthesiology

Alexandr Jalba, MD, PhD,

associate professor


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There is no standardpediatric patient that can be managed by

set formulas or memorized rules of thumb. Each patient is

unique and constantly changing !!! The surgeon faced with a sick infant or child must have a

system or approach that permits flexibility and

individualization. There are several essential ingredients to

such a system.

First, the surgeon needs a basic knowledge of the factors

that affect the surgical patient.

Second, techniques must be available that can be used to

evaluate the overall condition of the patient.

Then, utilizing the knowledge of surgical physiology and the

data obtained from the evaluation techniques, the surgeon

formulates a tentative therapeutic plan.


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This plan is put into operation for a specific period of time.

During that period, the responses of the patient to the therapy

are continuously monitored, usually by the same techniques

used in making the initial evaluation.

Analysis of the feedback information from the monitoring

allows reassessment of the therapeutic plan.

Changes are made, and the revised plan is put in operation.

Monitoring and readjustments are continuously made to meet

the changing needs of the patient.


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The system is dynamic and can be linked to a therapeutic poker

game with the surgeon and baby as opposing players (Fig. 1).

Figure 1.Therapeutic poker game. (Holder T.M. & Ashcraft K.W. Pediatric Surgery.

W.B. Sounders Company, 1980, p.2.)


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Factors in the care of the pediatric surgical patient

Five factors make the care of the critically ill pediatric

surgery patient a complex and difficult task. There are:

(1) the unique and constantly changing anatomic and

physiologic characteristicsof the neonate, the infant and the

child;

(2) the variations in gestational age, physical

development, and body size of individual patients of the

same chronologic age;

(3) pathologic conditions common to the pediatric period

that affect the management of the primary surgical disease;

(4) pathophysiologic changes produced by the primary

surgical disease; and

(5) the side effects of surgical treatmentitself.


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(1) Unique physiologic characteristics

The neonate, infant, child, and adolescent all differ

significantly from each other and from the adult.

It is during the neonatal period, however, that the pediatric

patient possesses the most distinctive and rapidly changing

physiologic characteristics.

This is due to the newborn infants adaptation to the

extrauterine environment, the continued process of organ

maturation, the demands of rapid growth and development,

and the small physical size.

For these reasons, we will place the emphasis on the

neonatal period, especially on circulatory, blood volume,

metabolic, host defense, and renal functioncharacteristics.


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Circulatory system before and after birth


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Metabolic characteristics

The newborn baby is a metabolically active organism with atotal energy expenditure well above that of the adult.

The basal metabolic rate is high, varying between 32 and 48

kcal per kilogram per 24 hr (the adult rate is 24 kcal per

kilogram in 24 hr). The infant requires approximately 38 kcal per kilogram per

hour for growth and development. In spite of these high

energy demands, energy reserves are low, and within a few

hours of birth, fuel must be supplied from external sourses.

Hepatic glycogen is depleted by 3 hours postnatally. Muscle

glycogen falls less rapidly but is completely utilized by

about 48 hours. Blood sugar rapidly decreases, reaching its

nadir when the child is about 6 hours of age.


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Host defense

The newborns host defenses against infection are generallysufficient to meet the challenge of most moderate bacterial

insults, but may not be able to meet a major insult.

Total complement activity is 50 per cent of adult levels.

C3, C3,5,6 complex, factor B, and properdin concentrations

are also low in comparison to the adult. Most studies suggestthat white blood cell function and opsonization are equal to

those of the more mature individual.

IgG is presenting adult amounts, but IgM, since it does not

pass through the placenta, is absent.

The plasma cell of the newborn infant is immunologically

competent to produce immunoglobulins but because of lack

of experience with antigenic substances may lag in the

production of antibodies in response to certain bacterial

invaders.


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Renal function

Neonatal renal function is adequate to meet the needs of thenormal full-term infant but may be limited during period of

stress.

Glomerular filtration and tubular function is lower than in the

adult. The concentrating ability of the kidney is reduced, and the

urine osmolality seldom reach 500 mOsm per kilogram.

Excretion of water, phosphate, hydrogen ion, and sodium is

reduced.


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(2) Variations in individual newborns

There are four different types of newborn infants:

(1) the full-term, full-size infant with gestational age of

38 weeks and a body weight greater than 2500 grams;

(2) the preterm infant with a gestational age below 38weeks and a birth weight appropriate for that age;

(3) the small for gestational age infant with gestational

age over 38 weeks and a body weight below 2500

grams; (4) a combination of (2) and (3), i.e. the preterm infant

who is also small for gestational age.


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The preterm baby

The characteristic that most significantly affects the survival of the preterm infant is theimmature state of the respiratory system. For the baby to adapt successfully to the air-

breathing state, the lungs must sufficiently develop anatomically and biochemically toallow for gas exchange.

Between 27 and 28 weeks of gestation (when body weight is 900 to 1000 grams),anatomic lung development has progressed to the extent that extrauterine survival is

possible. At this stage, gas exchange can take place in spite of the absence ofrecognizable alveoli. It is only after 30 to 33 weeks of gestation that true alveoli are

present. Once there is adequate lung tissue, the critical factor that determines extrauterine

adaptation and survival of the preterm infant is his capacity to produce the phospholipid-rich material, surfactant, that lines the respiratory epithelium, lowers surface tension, andstabilizes the gas exchange surfaces of the lung. This complex detergent is secreted byType 2 pneumatocytes. Synthesis and storage begins at about 16 weeks of gestation andincreases by 20 weeks. However, surfactant does not reach the surface of the lung until

between 28 and 38 weeks of gestation. The variation in the presence of surfactant inadequate amounts on the respiratory surfaces accounts, to a large extent, for the variationin pulmonary function between preterm infants of similar gestational age.

Even when sufficient anatomic and biochemical development occurs, the prematureinfants work in breathing is greatly increased. He has proportionately smaller alveoli,respiratory ducts, and bronchial diameters than full-term infants. A greater force must,therefore, be generated to expand the alveoli and more positive end-expiratory pressureused to keep the alveoli from deflating. Nevertheless, because of the weak, compliantnature of the preterm infants thoracic cage, the chest wall cannot be fixed duringinspiration, and a high negative intrathoracic pressure cannot be generated.


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The preterm baby (continuation)

The handling of the breakdown products of hemoglobin is also a difficult task

for the premature infant. The ability of the immature liver to conjugate bilirubinis reduced, the life span of the red blood cell is short, and the bilirubin load

presented to the circulation via the enterohepatic route is increased.

Physiologicjaundice is, therefore, higher in the preterm infant and persists for

a longer period of time. Unfortunately, the immature brain has an increased

susceptibility to the neurotoxic effects of high levels of unconjugated bilirubin,

and kernicterus can develop in the preterm baby at a relatively low level of

bilirubin. Among the many other problems associated with immaturity is the increased

susceptibility of the retina to the damaging effects of high oxygen levels. Even

brief exposures may results in retinolental fibroplasia. Feeding problems are

common in the preterm infant and result from a weak suck reflex, a small gastric

volume, and a relative decrease in disaccharide enzymes in the small intestine.

Because of the preterm babys large surface area and thin skin with an increased

permeability to water, evaporated water loss is as much as 6,5 times higher thanin the adult. To maintain fluid balance, fluid volumes as high as 130 to 175 ml

per kilogram per 24 hr may be required in the extremely premature infant. The

preterm infant often has a reduction in the serum factors necessary for white

blood cells to phagocytize and kill live bacteria. These deficits might, in part,

account for the increased vulnerability of the preterm infant to overwhelming

sepsis.


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The small for gestational age baby

Babies born after 38 weeks of gestation and who weigh less than 2500 grams are

thought to suffer from intrauterine growth retardation and are labeled as small

for gestational age or small for date infants. Factors that lead to growth

retardation may reside in the fetus (congenital abnormalities, sepsis or inherited

factors) or result from placental or maternal abnormalities. The small for

gestational age baby, compared with the preterm infant, tends to be

hypermetabolic, increasing the basal metabolism rate rapidly in the first 10 days

of life and then at a more gradual rate over a 6-week period. Because of their

small size, these infants have a relatively large surface area and heat loss isincreased. Body fat, because of intrauterine malnutrition, is frequently at levels

below 1 per cent of the body weight. The lack of insulation increases the

thermoregulatory problems of these babies.

Hypoglycemia may develop early in the small for gestation age baby than in the

normal full-term or preterm baby because of the high metabolic activity, the cost

of the thermoregulation, and the reduced energy stores due to intrauterinemalnutrition. The red blood cell volume and the total blood volume are much

higher than in the preterm or full-term infant, the red cell volume frequently

reaches levels of profound polycythemia and increased blood viscosity. Unlike

the premature infant, because of adequate length of gestation, intrauterine

development of the lungs of the small for gestational age baby usually results in

function approaching that of the normal full-term infant.


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(3) Associated pathologic conditions

There a host of complex pathologic conditions that occur

during the newborn, infant, childhood and adolescent periodsthat profoundly alter the physiologic state of the surgical

patient and have far-reaching effects on management and

ultimate survival.

Cystic fibrosis, juvenile diabetes, congenital heart disease,

hemophilia, and allergies are obvious examples.

Hyaline membrane disease is a classic example of the disease

that pediatric surgeon must be aware of in the care of

newborn surgical patient. It is the most common cause of

death in premature infants and develops in 60 per cent of

infants under 28 weeks of gestation and in 20 per cent ofinfants at 32 to 36 weeks of gestation. The hypoxia and low

flow state that develop during the disease play a major role in

the development of surgical lesions such as necrotizing

enterocolitis and patent ductus arteriosus.


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(4) Pathophysiologic effects of the

primary surgical disease

Many of the surgical diseases that affect the pediatric

patient are common to the adult age groups, but the majority

are unique to infancy and childhood.

Their pathophysiologic effects are varied and range from

the minimal derangements produced by a hydrocele to the

severe respiratory failure accompanying a diaphragmatic

hernia. Detailed descriptions of all these conditions are

contained in the later lections of this course.


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(5) Side effects of therapy

In the effort to treat the primary surgical problem, the

surgeon profoundly alters the patients physiology and

produces pathophysiologic changes. Many of these

alterations are of short duration, while others are permanent.

The effects of anesthesia, blood loss, operative tissue

damage, and the most drug are temporary, whereas the

removal of organs and the changes in anatomic design are

permanent.

In conclusion it is worth underlining once more that all these

factors make the care of severely ill pediatric surgical patient

a complex and difficult task.


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Thanks for your attention!

Peculiarities of Pediatric Surgical Patient

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