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