Neonatal Physiology

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Neonatal Physiology

• Tulane Pediatric Surgery

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Topics

• Fluids and Electrolytes
• Cardiopulmonary
• Temperature Regulation
• Jaundice
• Host Defenses
• Surgical Stress Response

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Fluids and Electrolytes

• Glucose
• Placental
• Glycogen Storage
• Gluconeogenesis
• Hypoglycemia
• SGA
• Surgical Pts
• Hyperglycemia

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Fluids and Electrolytes

• Calcium
• Placental Diffusion
• 75 third trimester
• Limited Stores
• Renal Immaturity
• Hypoparathyroidism
• Citrate can bind and decrease Ca

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Fluids and Electrolytes

• Magnesium
• Associated with Calcium
• Growth Retardation
• Maternal Diabetes
• Exchange Transfusions

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Fluids and Electrolytes

• Blood Volume
• Highest Delivery
• Cord Clamping
• Polycythemia
• Hctgt65
• Diabetes
• Toxemia
• SGA
• Partial Exchange

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Fluids and Electrolytes

• Hemolytic Anemia
• Maternal Antibodies
• Direct Coombs
• Rh most common
• Congenital Infections
• SS Dz

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Fluids and Electrolytes

• Anemia
• Premature Infants
• Erythropoeitin

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Fluids and Electrolytes

• Hemoglobin
• 80 Fetal
• Erythropoeisis 2-3 months
• P50 Adult Hgb 27 mmHg
• P50 Fetal Hgb 8 mmHg

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Jaundice

• Hemolysis
• Glucoronyl Transferase
• Unconjugated Hyperbilirubinemia
• Peaks 3rd Day 6-7mg/dl
• Resolves Day 10

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Jaundice

• Non Physiologic
• Breast Feeding
• Hemolytic Disease
• Hypothyroid
• Pyloric Stenosis
• Crigler-Najar
• Extravascular Blood
• Biliary Atresia
• Hepatitis

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Jaundice

• Non-Physiologic
• Conjugated gt 2mg/dl
• Rises gt 5mg/dl/day
• Born Jaundiced
• Doesnt Resolve

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Temperature Regulation

• Evaporation
• Conduction
• Convection
• Radiation

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Temperature Regulation

• Humidified Environments
• Incubator
• Ventilator Circuits
• Radiant Warmers
• Dry Heat
• Increased insensible losses
• Clothes/Blankets

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Temperature Regulation

• Hypothermia
• Hypoglycemia
• Vasoconstriction
• Coagulopathy
• Emergence from Anesthesia

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Renal Function

• Low GFR
• Better at 2 weeks
• Normal at 1-2 years
• Decreased Concentrating Ability
• 600mOsm
• Insensitive to ADH

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Cardiopulmonary

• Fetal Circulation
• Right to Left Shunts
• Foramen Ovale
• Ductus Arteriosus
• Hypoxemia
• Hypercarbia
• Acidosis

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Cardiopulmonary

• Persistent Fetal Circulation
• Sepsis
• Meconium Aspiration
• Congenital Diaphragmatic Hernia
• Idiopathic
• Treatment
• Ventilation
• Pharmacology
• ECMO

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Cardiopulmonary

• Surfactant Deficiency
• Premature
• Alveolar Stability
• Exogenous Administration

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Host Defenses

• Cellular Immunity
• WBCs
• Phagocytosis
• Adherence
• Killing
• Decreased Stores
• Poor Stem Cell Production

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Host Defenses

• Immunoglobulins
• IgG crosses the placenta
• Poor Response to Antigen Challenge
• IgA and IgM
• No type specific Antibodies
• Decreased Complement System Function
• Increased Mortality with Pyogenic Bacterial
  Infections

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Surgical Stress Response

• Initially Poorly Understood
• Crude Monitoring
• Few Outcome Studies
• Myths
• Anesthetics Unsafe/Not Approved
• Pain
• Could Anesthesia Blunt Surgical Stress Response?

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Surgical Stress Response

• Measured Catecholamines, Insulin, Cortisol.
• Adult Physiology
• Levels Decreased when Anesthesia Administered

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