Physiological Response of Newborn to Birth
Chapter 23
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
Chemical Stimuli
• Fetal acidosis, decrease in PO2,increase PCO2
• Cord clamped, stress of labor
• Stimulation of medulla
Thermal and Sensory
• Shock of cold environment
• Nerve ending stimulated
• Cold stress
• Tactile, auditory and visual stimulation
• Encourage skin to skin contact
Cardiopulmonary Adaptation
• Blood flow to lungs established
• Oxygen saturation
• Newborn anatomy restricts lung expansion
• Periodic breathing
• Obligate nose breathers
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
Cardiac Fx
• Normal rate
• BP
• Most murmurs transient and benign
• Right ventricle versus left ventricle
• Pressure gradient changes from left to right
Hemodynamics
• RBC shorter life span
• Rise in HCT
• Stress response
• Cord clamping
• Gestational age
• Presence of hemorrhage
• Site of blood sample
Temperature
• Metabolism and O2 consumption increase with heat loss
• Thin skin, decreased fat
• Blood vessels close to surface
• Flexed posture
• Premature infants
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
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
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
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
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
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
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
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
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
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
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
Neurological Fx
• Able to habituate
• Able to fixate on faces or objects with contrast
• Blinking reflex
• Growth is cephalocaudal
• Reflexes present
• Defensive motor ability