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Diseases of I n f a n c y & C h i l d h o o d

Diseases of I n f a n c y & C h i l d h o o d. Diseases of Infancy and Childhood. Congenital Anomalies Birth Weight and Gestational Age Birth Injuries Perinatal Infections Respiratory Distress Syndrome (RDS) Necrotizing Enterocolitis Intraventricular Hemorrhage Hydrops

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Diseases of I n f a n c y & C h i l d h o o d

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  1. Diseases of Infancy & Childhood

  2. Diseases of Infancyand Childhood • Congenital Anomalies • Birth Weight and Gestational Age • Birth Injuries • Perinatal Infections • Respiratory Distress Syndrome (RDS) • Necrotizing Enterocolitis • Intraventricular Hemorrhage • Hydrops • Inborn Metabolic/Genetic Errors • Sudden Infant Death Syndrome (SIDS) • Tumors

  3. Major Time Spans • Neonatal period • first four weeks of life • Infancy • the first year of life • Age 1 – 4 years (preschool) • Age 5 – 14 years (school age)

  4. MORTALITY by TIME SPAN • NEONATE (0-4 WEEKS): CONGENITAL, PREMATURITY • UNDER ONE YEAR: CONGENITAL, PREMATURITY/WEIGHT, SIDS • 1-4 YEARS: ACCIDENTS, CONGENITAL, TUMORS • 5-14 YEARS: ACCIDENTS, TUMORS, HOMICIDES • 15-24 YEARS: ACCIDENTS, HOMICIDE, SUICIDE (NONE ARE “NATURAL” CAUSES)

  5. 1Rates are expressed per 100,000 population 2Excludes congenital heart disease

  6. Cause of Death Related with Age UNDER 1 YEAR • Congenital malformations, deformations, and chromosomal anomalies    • Disorders related to short gestation and low birth weight    • Sudden infant death syndrome (SIDS)    • Newborn affected by maternal complications of pregnancy    • Newborn affected by complications of placenta, cord, and membranes    • Respiratory distress of newborn    • Accidents (unintentional injuries)    • Bacterial sepsis of newborn    • Intrauterine hypoxia and birth asphyxia    • Diseases of the circulatory system

  7. 1–4 YEARS Accidents and adverse effects    Congenital malformations, deformations, and chromosomal abnormalities    Malignant neoplasms    Homicide and legal intervention    Diseases of the heart (Excludes congenital heart disease) Influenza and pneumonia

  8. 5–14 YEARS Accidents and adverse effects    Malignant neoplasms    Homicide and legal intervention    Congenital malformations, deformations, and chromosomal abnormalities    Suicide    Diseases of the heart

  9. 15–24 YEARS Accidents and adverse effects    Homicide    Suicide    Malignant neoplasms    Diseases of the heart

  10. Congenital Anomalies • morphologic defects that are present at birth • the exact cause remains unknown in at least half to three quarters of the cases • common known causes of congenital anomalies: • Genetic • Environmental • Multifactorial

  11. Genetic • Anomalies that are known to be genetic in origin can be divided into two groups: • Those associated with chromosomal aberrations    • Those arising from single-gene mutations (“mendelian disorders”) trisomy 21 (Down syndrome) is the only one that approaches a birth frequency of greater than 10 in 10,000 total births

  12. Congenital Anomalies • Definitions • Causes • Pathogenesis

  13. Malformations primary errors of morphogenesis, usually multifactorial e.g. congenital heart defect Disruptions secondary disruptions of previously normal organ or body region e.g. amniotic bands Deformations extrinsic disturbance of development by biomechanical forces e.g. uterine constraint Sequence a pattern of cascade anomalies explained by a single localized initiating event with secondary defects in other organs e.g. Oligohydramnios (Or Potter) Sequence Syndrome a constellation of developmental abnormalities believed to be pathologically related e.g Turner syndrome

  14. Malformations Polydactyly & syndactyly Cleft Lip Severe Lethal Malformation

  15. Disruption by an amniotic band

  16. Oligohydramnios (Or Potter) Sequence Oligohydramnios (decreased amniotic fluid) Renal agenesis Amniotic leak Fetal Compression flattened facies club foot (talipes equinovarus) Pulmonary hypoplasia fetal respiratory motions important for lung development Breech Presentation

  17. The Oligohydramnios “Sequence”

  18. Infant with oligohydramnios sequence

  19. Organ Specific Anomalies Agenesis: complete absence of an organ Atresia: absence of an opening Hypoplasia: incomplete development or under- development of an organ with decreased numbers of cells Hyperplasia: overdevelopment of an organ associated with increased numbers of cells Hypertrophy: increase in size with no change in number of cells Dysplasia: in the context of malformations (versus neoplasia) describes an abnormal organization of cells

  20. Implantation and the Survival of Early Pregnancy • Only 50-60% of all conceptions advance beyond 20 weeks • Implantation occurs at day 6-7 • 75% of loses are implantation failures and are not recognized • Pregnancy loss after implantation is 25-40% NEJM 2001; 345:1400-1408

  21. #1 #2 #3

  22. CAUSES OF ANOMALIES Genetic karyotypic aberrations single gene mutations Environmental infection maternal disease drugs and chemicals irradiation Multifactorial Unknown

  23. Embryonic Development • Embryonic period • weeks 1- 8 of pregnancy • organogenesis occurs in this period • Fetal period • weeks 9 to 38 • marked by further growth and maturation

  24. Critical Periods Of Development

  25. Genetic Causes • Karyotypic abnormalities • 80-90% of fetuses with aneuploidy die in utero • trisomy 21 (Down syndrome) most common karyotypic abnormality (21,18,13) • sex chromosome abnormalities next most common (Turner and Klinefelter) • autosomal chromosomal deletion usually lethal • karyotyping frequently done with aborted fetuses with repeated abortions • Single gene mutations • covered in separate chapters

  26. Maternal Viral Infection Rubella (German measles) at risk period first 16 weeks gestation defects in lens (cataracts), heart, and CNS (deafness and mental retardation) rubella immune status important part of prenatal workup Cytomegalovirus most common fetal infection highest at risk period is second trimester central nervous system infection predominates

  27. Drugs and Chemicals • Drugs • 13 cis-retinoic acid (acne agent) • warfarin • angiotensin converting enzyme inhibitors (ACEI) • anticonvulsants • oral diabetic agents • thalidomide • Alcohol • Tobacco

  28. Teratogen Actions • • Proper cell migration to predetermined locations that influence the development of other structures • • Cell proliferation, which determines the size and form of embryonic organs • • Cellular interactions among tissues derived from different structures (e.g., ectoderm, mesoderm), which affect the differentiation of one or both of these tissues • • Cell-matrix associations, which affect growth and differentiation • • Programmed cell death (apoptosis), which, as we have seen, allows orderly organization of tissues and organs during embryogenesis • • Hormonal influences and mechanical forces, which affect morphogenesis at many levels

  29. Diabetes Mellitus • Fetal Macrosomy (>10 pounds) • maternal hyperglycemia increases insulin secretion by fetal pancreas, insulin acts with growth hormone effects • Diabetic Embryopathy • most crucial period is immediately post fertilization • malformations increased 4-10 fold with uncontrolled diabetes, involving heart and CNS • Oral agents not approved in pregnancy • Diabetics attempting to conceive should be placed on insulin

  30. Birth Weight and Gestational Age • Appropriate for gestational age (AGA) • between 10 and 90th percentile for gestational age • Small for gestational age (SGA) , <10% • Large for gestational age (LGA) , >90% • Preterm • born before 37 weeks (<2500 grams) • Post-Term • delivered after 42 weeks

  31. Prematurity • Defined as gestational age < 37 weeks • Second most common cause of neonatal mortality (after congenital anomalies) • Risk factors for prematurity • Preterm Premature Rupture Of fetal Membranes (PPROM) • Intrauterine infection • Uterine, cervical, and placental abnormalities • Multiple gestation

  32. Fetal Growth Restriction • At least 1/3 of infants born at term are < 2.5kg • Undergrown rather than immature • Commonly underlies SGA (small for gestational age) • Prenatal diagnosis: ultrasound measurements • Classification • Fetal • Placental • Maternal

  33. Fetal FGR • Chromosomal abnormalities • 17% of FGR overall • up to 66% of fetuses with ultrasound malformations • Fetal Infection • Infection: TORCH (Toxoplasmosis, Other, Rubella, Cytomegalovirus, Herpes) • Characterized by symmetric growth restriction – head and trunk proportionally involved

  34. Placental FGR • Vascular • umbilical cord anomalies (single artery, constrictions, etc) • thrombosis and infarction • multiple gestation • Confined placental mosaicism • mutation in trophoblast • trisomy is common • Placental FGR tends to cause asymmetric growth with relative sparing of the head

  35. Maternal FGR • Most common cause of FGR by far • Vascular diseases • preeclampsia (toxemia of pregnancy) • hypertension • Toxins • ethanol • narcotics and cocaine • heavy smoking

  36. Organ Immaturity • Lungs • alveoli differentiate in 7th month • surfactant deficiency • Kidneys • glomerular differentiation is incomplete • Brain • impaired homeostasis of temperature • vasomotor control unstable • Liver • inability to conjugate and excrete bilirubin

  37. APGAR (Appearance, Pulse, Grimace, Activity, Respiration)

  38. Apgar Score and 28 Day Mortality • Score may be evaluated at 1 and 5 minutes • 5 minute scores • 0-1, 50% mortality • 4, 20% mortality • ≥ 7, nearly 0% mortality

  39. Perinatal Infection Transcervical (ascending) inhalation of infected amniotic fluid pneumonia, sepsis, meningitis commonly occurs with PROM passage through infected birth canal herpes virus– caesarian section for active herpes Transplacental (hematogenous) mostly viral and parasitic HIV—at delivery with maternal to fetal transfusion TORCH parvovirus B19 (Fifth), erythema infectiosum bacterial Listeria monocytogenes

  40. Fetal Lung Maturation

  41. STAGES OF NORMAL LUNG GROWTH Embryonic - first 5 weeks; formation of proximal airways Pseudoglandular - 5-16 weeks; formation of conducting airways Canalicular - 16-24 weeks; formation of acini Saccular - 24 - 36 weeks; development of gas-exchange units Alveolar - 36 weeks and up; expansion of surface area

  42. PHYSIOLOGIC MATURATION(Surfactant Production) • Type 2 pneumocytes appear at 24-26 weeks • Responsible for reduction of alveolar surface tension. • LaPlace’s Law • Lipid profile as indicator of lung maturity • L/S Ratio • Flourescence Polarization - FLM • Many other factors influence lung maturation

  43. Neonatal Respiratory Distress Syndrome (RDS) 60,000 cases / year in USA with 5000 deaths Incidence is inversely proportional to gestational age The cause is lung immaturity with decreased alveolar surfactant surfactant decreases surface tension first breath is the hardest since lungs must be expanded without surfactant, lungs collapse with each breath

  44. RDS Risk Factors • 1) Prematurity • by far the greatest risk factor • affected infants are nearly always premature • 2) Maternal diabetes mellitus • insulin suppresses surfactant secretion • 3) Cesarean delivery • normal delivery process stimulates surfactant secretion

  45. RDS Pathology • Gross • solid and airless (no crepitance) • sink in water • appearance is similar to liver tissue* • Microscopic • atelectasis and dilation of alveoli • hyaline membranes composed of fibrin and cell debris line alveoli (HMD former name) • minimal inflammation

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