Cardiovascular transition

1. air inflates the lungs→↓ pulmonary vascular resistance→ ↓ pulmonary artery pressure→↓ in pressure in the R

atrium→↑ pulmonary blood flow to L side of heart→ ↑ the pressure in the L atrium=functional closing of the foramen ovale (functionally closed-1-2 hrs,

anatomically closed-30 months

2. in utero, fetal pO2 is 27 mm HG—after birth, pO2 ∆ to 50 mm Hg in the arterial blood→constricture of the ductus arteriosus—functional closure in 10-24 hrs -permanent closure in 3-4 weeks

3. pulmonary blood vessels dilate in response to O2 fetal lung fluid moves into the interstitial spaces

(any ↓ O2-ductus dilates, pulmonary vessels constrict)

4. clamping of the umbilical cord closes the umbilical arteries, umbilical vein, and ductus venosus which convert into ligaments-fibrosis within 2 months II. Neurological adaptation

A. Thermoregulation

1. newborn’s ability to produce heat is often = to adults but have a tendency towards rapid heat loss

2. heat loss from: thin skin, little sub Q fat, blood vessels close to surface, heat easily transferred from internal to skin

3. 3x the body surface than adults=4x heat loss 4. flexed position helps preserve heat—problem with

premies is poor muscle tone leads to less flex 5. evaporation-heat loss thru wet skin exposed to air

-dry baby immediately at birth

6. conduction-loss of heat from body surface to cooler surface in direct contact

7. convection-heat transferred to cooler ambient air -keep out of drafts, wrap in blanket with hat on head 8. radiation-transfer of heat to cooler object not in

direct contact with infant

-keep cribs away from outer windows 9. Thermogeneis

a. Nonshivering thermogenesis (NST)

primarily thru brown fat ( highly vascular fat found only in infants with abundant supply of blood vessels/nerve endings, found at neck, kidneys, adrenals, sternum and intrascapulary region)→heat produced by lipid metabolic activity → warm baby (preterm infants lack brown fat)

b. secondarily thru increased metabolic activity in liver, brain, and heart

c. shivering begins when thermal receptors in skin detect a drop in the skin temp-rare in neonates 10. cold stress-

a. ↑ metabolism = ↑ need for O2 and glucose regardless of gestational age or condition b. if prolonged-leads to resp. difficulty

c. O2 consumption diverted from maintaining brain/heart function to thermogenesis

d. decreased pulmonary perfusion may lead to an open ductus arteriosus

e. hypoglycemia

f. fatty acids released = metabolic acidosis g. fatty acids in blood can interfere with

bilirubin transport = risk for jaundice B. Reflexes

1. Moro (startle)

Usually present for first 3-4 months 2. Palmar, plantar grasp

Fingers/toes curl around examiner’s fingers palmar lessens by 3-4 months

3. Tonic neck fencing position

complete response gone by 3-4 months 4. Sucking and rooting

head turns towards stimulus and sucks C. Sensory adaptation

1. Vision

a. at birth, muscles in eye area are immature (transient strabismus)

b. clearest vision within 10-20 inches c. sensitive to light

d. at 5 days old, attracted to black/white patterns e. able to see colors at 2 months

f. tear glands developed by 2-8 weeks

g. by 6 months, their visual acuity is ½ of adults h. prefer patterns to plain surfaces

i. eye color will not be set until 3-12 months 2. Hearing

a. like an adult’s after draining of amniotic fluid b. loud sounds make baby have startle reflex c. decrease motor activity in presence of low

frequency sounds such as a heartbeat d. hearing loss is a common major abnormality

1-3/1000 normal term infants have bilateral hearing loss

3. Touch

a. responses to touch on all parts of the body b. face, hands, soles being most sensitive 4. Taste

a. can distinguish tastes

b. prefer glucose water to plain water 5. Smell

a. react to strong odors by turning head away b. can differentiate their mother’s breast milk by

III. Hematological adaptation A. Neonatal differences

1. RBC’s and H & H

a. at birth, levels are higher than adults -Hgb—14-24 g/dl

-Hct—44-64% if > 65% = polycythemia -RBC—5.1-5.3/mm3_-1st _{24-48 hrs of life}

(neonatal RBC’s have a lower survival rate compared to adults)→physiological anemia c. delay of cord clamping shifts plasma to

extravascular spaces with ↑ lab results 2. Leukocytes

a. WBC 9-30,000 per mm3 _{is normal at birth} b. will rise then decline to a level of 11,500 c. infection not well tolerated in infants with

sepsis usually accompanied by a loss in WBC 3. Platelets

a. 200,000-300,000/mm3

b. factors II, VII, IX, and X decreased due to lack of Vitamin K-not adult level until ≥ 9 months 4. Blood Groups

a. cord blood sample taken to determine infant’s blood group and Rh status

b. Rh neg mom’s receive Rhogam if Rh + baby 5. Blood Volume

a. 80-85 ml/kg

b. at birth, blood volume approx. 300 ml

c. preterms have greater blood volume due to a greater plasma volume, not RBC mass 6. Heart rate and BP

a. HR averages at140 beats/min at birth b. rises just after birth

c. full term infants HR between 120-160 bt/min d. PMI (point of maximal impulse) left chest

(apical pulse)

e. ½ of heart murmurs heard at birth disappear by 6 months

IV. Musculoskeletal System A. Head and upper body

1. at birth, more cartilage than bone

2. face looks small in relationship to skull R/T molding (overlapping of the skull bones)

3. fontanelles

a. anterior closes at 12-18 months b. posterior closes at 8-12 weeks c. bulging fontanelles mean ↑ ICP

d. sunken fontanelles mean dehydration 4. craniostenosis-contracted skull due to premature

closure of the cranial sutures-need surgery 5. Caput succedaneum

a. edema of the scalp b. may cross suture lines c. disappears in 1-4 dys 6. Cephalohematoma

a. collection of blood between the skull bone and the periosteum-doesn’t cross suture lines

b. may be spontaneous or due to vacuum or forceps delivery

c. resolves in 2-4 weeks d. may lead to jaundice 7. neck/shoulders

a. shoulder dystocia→ brachial plexus injury -fx of scapula or clavicle (clavicle is the most commonly fx bone during delivery process) -immobilize in a sling

B. Extremities