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PedSurg Handbook-Dr Lugo-Vicente.pdf

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  PEDIATRIC SURGERY HANDBOOK Humberto L Lugo-Vicente, MD, FACS, FAAP* Professor/Associate Director of Pediatric Surgery University of Puerto Rico School of Medicine University Pediatric HospitalChief - Section Pediatric Surgery San Pablo Medical Center <titolugo@coqui.net>  2 - PedSurg Handbook/Dr Lugo-Vicente CONTENTI. INTRODUCTION V. GASTROINTESTINAL BLEEDING  A. Neonatal Physiologic CharacteristicsA. Upper GI bleeding (Newborn) B. Lower GI bleeding (Newborn) 1. Water Metabolism1. Necrotizing Enterocolitis (NEC)C. Upper GI bleeding (Older child) 2. Fluid and Electrolytes ConceptsD. Lower GI bleeding (Older child) 1- Anal FissureB. Variations in Individual Newborns 2- Meckel’s Diverticulum1. Types of Newborns Infants3- Polyps4- Familial Adenomatous Polyposis 2. Metabolic and Host Defenses VI. PANCREATIC HEPATIC, BILIARY and SPLENIC DISORDERS 3. Surgical Response of Newborns II. HEAD AND NECK LESIONS  A. Cervical LymphadenopathyB. PancreatitisB. Congenital TorticollisC. Pancreatic CystsC. Thyroglossal Duct CystsD. Hepatic CystsE. Biliary AtresiaD. Branchial Cleft FistulasF. Biliary hypoplasiaE. Cystic HygromaF. Cat’s Scratch Disease III. OBSTRUCTIVE and GI PROBLEMS Logical Approach to Neonatal Intestinal Obstruction (by Jordan Weitzman, MD) A. Esophageal Atresia and Stenosis B. Achalasia C. Gastro-Duodenal Anomalies 1. Gastric Anomalies2. Pyloric Stenosis3. Duodenal Malformations D. Malrotation and Volvulus E. Intestinal Atresias F. Meconium Ileus G. Hirschsprung's disease H. Imperforate Anus I. Duplications J. Intussusception K. Appendicitis L. Chronic Intestinal Pseudo-obstruction A. Labial Adhesions in Infants M. BezoarsB. Ovarian Cysts N. Carcinoid syndromeO. Meconium-related disordersC. Breast Disorders1. Meconium IleusD. Congenital Adrenal Hyperplasia2. Meconium Peritonitis3. Meconium Plug syndrome and Left hypoplastic colon syndromeE. Testicular Feminization Syndrome P. Foreign Body Ingestion F. Mixed gonadal Dysgenesis IV. HERNIAS, THORACIC CONDITIONS AND ABDOMINAL WALL DEFECT   A. Diaphragmatic hernias 1- Congenital Diaphragmatic Hernia (Bochdalek)2- Morgagni Hernias3- Hiatal Hernias B. Lung Bud Anomalies1. Congenital Lobar Emphysema2. Pulmonary SequestrationSpecific Reading3. Cystic Adenomatoid MalformationGeneral Reading4. Bronchogenic CystC. ChylothoraxD. EmpyemaE. Spontaneous PneumothoraxF. PneumatoceleG. Inguinal hernias, Hydroceles, Undescended Testis and epigastric hernias H. Mediastinal Cysts I. Umbilical hernias J. Omphalocele and Gastroschisis K. Femoral Hernias A. Annular Pancreas/Pancreas DivisumG. Choledochal CystH. CholelithiasisI. Idiopathic Perforation Bile DuctJ. Splenic Cysts, splenoptosis, Spherocytosis and AspleniasK. Splenic TraumaL. Adrenal Hemorrhage VII. TUMORS  A. Wilms tumor B. Neuroblastoma C. Rhabdomyosarcoma D. Liver Tumors E. Teratomas F. Ovarian Tumors G. Thyroid NodulesH. Burkitt’s Lymphoma VIII. GYNECOLOGIC and INTERSEXUAL CONSIDERATIONS G. Müllerian Duct SyndromeH. Hydrometrocolpos IX. PRENATAL CONGENITAL MALFORMATIONS  A. Fetal Surgery B. Fetal Intestinal ObstructionC. Fetal Abdominal Wall Defects X. SUGGESTED READING  3 - PedSurg Handbook/Dr Lugo-Vicente I. INTRODUCTION   A. Neonatal Physiologic Characteristics   1. Water metabolism Water represents 70 to 80% of the body weight of the normal neonate and premature babyrespectively. Total body water (TBW) varies inversely with fat content, and prematures have less fat deposits.TBW is distributed into extracellular fluid (ECF) and intracellular fluid (ICF) compartment. The ECFcompartment is one-third the TBW with sodium as principal cation, and chloride and bicarbonate as anions.The ICF compartment is two-third the TBW with potassium the principal cation. The Newborn's metabolic rateis high and extra energy is needed for maintenance of body temperature and growth. A change in body water occurs upon entrance of the fetus to his new extrauterine existence. There is a gradual decrease in body water and the extracellular fluid compartment with a concomitant increase in the intracellular fluid compartment. Thisshift is interrupted with a premature birth. The newborn's body surface area is relatively much greater than theadults and heat loss is a major factor. Insensible water loss are from the lung (1/3) and skin (2/3).Transepithelial (skin) water is the major component and decreases with increase in post-natal age. Insensiblewater loss is affected by gestational age, body temperature (radiant warmers), and phototherapy.Neonatal renal function is generally adequate to meet the needs of the normal full-term infant but may belimited during periods of stress. Renal characteristics of newborns are a low glomerular filtration rate andconcentration ability (limited urea in medullary interticium) which makes them less tolerant to dehydration. Theneonate is metabolically active and production of solute to excrete in the urine is high. The kidney in thenewborn can only concentrate to about 400 mOsm/L initially (500-600 mOsm/L the full-term compared to 1200mOsm/L for an adult), and therefore requires 2-4 cc/kg/hr urine production to clear the renal solute load. Theolder child needs about 1-2 cc/kg/hr and the adult 0.5-1 cc/kg/hr. 2. Fluid and Electrolytes ConceptsCellular energy mediated active transport of electrolytes along membranes is the most importantmechanism of achieving and maintaining normal volume and composition of fluid compartments. Infants canretain sodium but cannot excrete excessive sodium. Electrolytes requirements of the full-term neonate are:Sodium 2-3 meq/kg/day, potassium 1-2 meq/kg/day, chloride 3-5 meq/kg/day at a rate of fluid of 100 cc/kg/24hrs for the first 10 kg of weight. As a rule of thumb, the daily fluid requirements can be approximated too:prematures 120-150 cc/kg/24 hrsneonates (term) 100 cc/kg/24 hrsInfants >10 kg 1000 cc+ 50 cc/kg/24 hrs. Special need of preterm babies fluid therapy are: conservative approach, consider body weightchanges, sodium balance and ECF tonicity. They are susceptible to both sodium loss and sodium and volumeoverloading. High intravenous therapy can lead to patent PDA, bronchopulmonary dysplasia, enterocolitis andintraventricular hemorrhage. Impaired ability to excrete a sodium load that can be amplify with surgical stress(progressive renal retention of sodium). Estimations of daily fluid requirements should take into consideration:(1) urinary water losses, (2) gastrointestinal losses, (3) insensible water losses, and (4) surgical losses (drains).Blood Volumes estimates of help during surgical blood loss are: premature 85-100 cc/kg, term 85cc/kg, and infant 70-80 cc/kg. The degree of dehydration can be measured by clinical parameters such as:body weight, tissue turgor, state of peripheral circulation, depression of fontanelle, dryness of the mouth andurine output. Intravenous nutrition is one of the major advances in neonatal surgery and will be required whenit is obvious that the period of starvation will go beyond five days. Oral feeding is the best method and breast is best source. Newborn infants requires 100-200calories/kg/day for normal growth. This is increased during stress, cold, infection, surgery and trauma. Minimumdaily requirement are 2-3 gm/kg of protein, 10-15 gm/kg of carbohydrate and small amount of essential fattyacids. B. Variations in Individual Newborns1. Types of Newborns Infants a) The full-term, full-size infant with a gestational age of 38 weeks and a body weight greater than 2500grams (TAGA)- they received adequate intrauterine nutrition, passed all fetal tasks and their physiologicfunctions are predictable. b) The preterm infant with a gestational age below 38 weeks and a birth weightappropriate for that age (PreTAGA); c) The small-for-gestational-age infant (SGA) with a gestational age over 38 weeks and a body weight below 2500 grams- has suffered growth retardation in utero. d) A combination of (b) and (c), i.e., the preterm infant who is also small for gestational age.  4 - PedSurg Handbook/Dr Lugo-Vicente The characteristic that most significantly affects the survival of the preterm infant is the immature stateof the respiratory system. Between 27 and 28 weeks of gestation (900-1000 grams), anatomic lungdevelopment has progressed to the extent that extrauterine survival is possible. It is only after 30 to 32 weeksof gestation that true alveoli are present. Once there is adequate lung tissue, the critical factor that decidesextrauterine adaptation and survival of the preterm infant is his capabilities to produce the phospholipid-richmaterial, surfactant that lines the respiratory epithelium. 2. Metabolic and Host Defenses Handling of the breakdown products of hemoglobin is also a difficult task for the premature infant. Theability of the immature liver to conjugate bilirubin is reduced, the life span of the red blood cell is short, and thebilirubin load presented to the circulation via the enterohepatic route is increased. Physiologic jaundice is,therefore, higher in the preterm infant and persists for a longer period. Unfortunately, the immature brain hasan increased susceptibility to the neurotoxic effects of high levels of unconjugated bilirubin, and kernicterus candevelop in the preterm baby at a relatively low level of bilirubin.Other problems affecting the baby include the rapid development of hypoglycemia (35 mg%),hypocalcemia and hypothermia. Newborns have a poorly developed gluconeogenesis system, and dependson glycolysis from liver glycogen stores (depleted 2-3 hrs after birth) and enteral nutrition. Immature infants candevelop hyperglycemia from reduced insulin response to glucose causing intraventricular hemorrhage andglycosuria. The preterm and surgical neonate is more prone to hypocalcemia due to reduced stores, renalimmaturity, and relative hypoparathyroidism (high fetal calcium levels). Symptoms are jitteriness and seizureswith increase muscle tone. Calcium maintenance is 50 mg/kg/day.Human beings are homeothermic organisms because of thermoregulation. This equilibrium ismaintained by a delicate balance between heat produced and heal lost. Heat production mechanisms are:voluntary muscle activity increasing metabolic demands, involuntary muscle activity (shivering) and non-shivering (metabolizing brown fat). Heat loss occurs from heat flow from center of the body to the surface andfrom the surface to the environment by evaporation, conduction, convection and radiation. There is anassociation between hypothermia and mortality in the NICU's. The surgical neonate is prone to hypothermia.Infant produce heat by increasing metabolic activity and using brown fat. Below the 35°C the newbornexperiences lassitude, depressed respiration, bradycardia, metabolic acidosis, hypoglycemia, hyperkalemia,elevated BUN and oliguria (neonatal cold injury syndrome). Factors that precipitate further these problems are:prematurity, prolonged surgery, and eviscerated bowel (gastroschisis). Practical considerations to maintaintemperature control are the use of humidified and heated inhalant gases during anesthesia, and during all NICUprocedures use radiant heater with skin thermistor-activated servo-control mechanism. The newborn's host defenses against infection are generally sufficient to meet the challenge of mostmoderate bacterial insults, but may not be able to meet a major insult. Total complement activity is 50% of adults levels. C3,C4,C5 complex, factor B, and properdin concentration are also low in comparison to the adult.IgM, since it does not pass the placenta, is absent. 3- Surgical Response of Newborns The endocrine and metabolic response to surgical stress in newborns (NB) is characterized bycatabolic metabolism. An initial elevation in cathecolamines, cortisol and endorphins upon stimulation bynoxious stimuli occurs; a defense mechanism of the organism to mobilize stored energy reserves, form newones and start cellular catabolism. Cortisol circadian responsiveness during the first week of life is diminished,due to inmaturation of the adrenal gland. Cortisol is responsible for protein breakdown, release of gluconeogenic amino acids from muscle, and fat lipolysis with release of fatty acids. Glucagon secretion isincreased. Plasma insulin increase is a reflex to the hyperglycemic effect, although a resistance to its anabolicfunction is present. During surgical stress NB release glucose, fatty acids, ketone bodies, and amino acids;necessary to meet body energy needs in time of increase metabolic demands. Early postoperative parenteralnutrition can result in significant rate of weight gain due to solid tissue and water accumulation. Factorscorrelating with a prolonged catabolic response during surgery are: the degree of neuroendocrinologicalmaturation, duration of operation, amount of blood loss, type of surgical procedure, extent of surgical trauma,and associated conditions (hypothermia, prematurity, etc.). They could be detrimental due to the NB limitedreserves of nutrients, the high metabolic demands impose by growth, organ maturation and adaptation after birth. Anesthetics such as halothane and fentanyl can suppress such response in NB. II. HEAD AND NECK LESIONS

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Jan 14, 2019

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Jan 14, 2019
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