Physiological Response of Newborn to Birth

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Physiological Response of Newborn to Birth

• Chapter 23

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Neonatal Transition

• Surfactant production
• Breathing initiated by mechanical, sensory,
  chemical, thermal changes.
• Mechanical- pressure from chest compression,
  recoil
• Remaining fluid pulled into interstitial fluid
• Problems r/t inadequate chest compression

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Chemical Stimuli

• Fetal acidosis, decrease in PO2,increase PCO2
• Cord clamped, stress of labor
• Stimulation of medulla

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Thermal and Sensory

• Shock of cold environment
• Nerve ending stimulated
• Cold stress
• Tactile, auditory and visual stimulation
• Encourage skin to skin contact

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Cardiopulmonary Adaptation

• Blood flow to lungs established
• Oxygen saturation
• Newborn anatomy restricts lung expansion
• Periodic breathing
• Obligate nose breathers

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Cardiopulmonary Adaptation

• Clamping of cord, shut off the hose, increase
  in blood pressure
• Perfusion increased by pulmonary blood flow and
  dilation pulmonary vessels.
• Decrease in vascular resistance
• Pressure change closes foramen ovale
• Ductus arteriosis closes due to PO2
• Ductus venosis closure leads to liver profuse

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Cardiac Fx

• Normal rate
• BP
• Most murmurs transient and benign
• Right ventricle versus left ventricle
• Pressure gradient changes from left to right

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Hemodynamics

• RBC shorter life span
• Rise in HCT
• Stress response
• Cord clamping
• Gestational age
• Presence of hemorrhage
• Site of blood sample

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Temperature

• Metabolism and O2 consumption increase with heat
  loss
• Thin skin, decreased fat
• Blood vessels close to surface
• Flexed posture
• Premature infants

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Heat Loss

• Large body surface Vessels close to skin
• Convection- cool air currents, door open
• Radiation- heat transfers to cooler surface,
  place cool object on warmer
• Evaporation-water converted to vapor, wet baby
• Conduction- loss of heat due to direct contact
  with object

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Thermogenesis

• Increase in BMR, and activity generate heat
• Nonshivering thermogenesis (NST)
• Infant uses stores of brown fat
• Brown fat metabolized quickly to produce heat
• Do not chill newborns
• Cold stress can delay drug metabolism

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Hepatic Adaptation

• Iron stored in fetal liver, last for 6 months
• Energy crunch caused by labor and loss of
  maternal glucose
• Newborn converts from use of carbohydrate
  metabolism to fat metabolism

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Conjugation of Bilirubin

• Bilirubin is byproduct of breakdown of RBCs
• In utero bilirubun excreted by placenta
• Bilirubin needs to be conjugated to be excreted.
• Enzymes in liver conjugate bilirubin- bacteria
  transforms into urobilirubin
• Low levels of glucuronyl transferase and immature
  liver function

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Physiologic Jaundice

• Normal response 2-3 days after birth
• Caused by increase volume and RBC destruction
• Bilirubin not flushed from plasma
• Bilirubin not conjugated
• Decreased bacterial flora and motility

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Nursing

• Room environment-avoid pink
• Head to toe, blanch and assess for yellow
• Maintain temp
• Monitor for excretion
• Feed early
• Phototherapy for newborns over 13mg/dl

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Breastfeeding Jaundice

• Peaks in 2-3 weeks
• Composition of breast milk may interfere with
  conjugation
• If above 20mg.dl may be asked to cease
• Continue to pump
• Reassure moms

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Coagulation

• Some coagulation factors are Vit. K dependent
• At birth bacteria in colon not present for Vit. K
  synthesis
• Dilantin and Coumadin associated with bleeding
  issues

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GI

• Lactose(carb.),proteins easily digested
• Starches not easily digested
• Lack of pancreatic enzyme limits fat digest.
• Some regurge nl, burp do not overfeed
• Need 120 cal/kg/day, 5-10 weight loss.
• Meconium- debris, dark, tarry
• Differentiate breast feed from bottle fed

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Kidney Fx

• Inability to concentrate urine
• Decrease in GFR, unable to diurese quickly
• Most void within 24 hrs., 6/day
• Increase 5-25/day after 2 days
• Blood in female diaper due to pseudomenstruation

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Immunity

• Immunoglobin IgG transferred to fetus, passive
  acquired immunity
• Length of immunity to bacteria and virus vary
• Lack of IgM, fetus susceptible to gram -
• IgA protects, gi, int, eyes, high concentration
  in colostrum

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Neurological Fx

• Able to habituate
• Able to fixate on faces or objects with contrast
• Blinking reflex
• Growth is cephalocaudal
• Reflexes present
• Defensive motor ability