The Newborn Adaptation

Milam 2/5/10

  • Respiratory Adaptations
  • Intrauterine Preparation
  • Fetal lung development
  • 0-20 week = developing structures
  • 20-24 weeks= alveolar ducts begin to appear
  • 24-28 = type I & type II alveolar epithelial cells differentiate; surfactant production begins
  • Type I cells structures necessary for gas exchange
  • Type II cells synthesis of surfactant
  • 28-32 weeks = increased production of surfactant by type II cells
  • 35 weeks = peak production of surfactant
  • Surfactant
  • Lipoprotein produced by lungs
  • Major Determinant of Respiratory Ability
  • Reduces surface tension within the alveoli
  • Lecithin/Sphingomyelin (L/S) ratio has diagnostic value as to fetal lung maturity
  • L/S ratio of 2:1 correlates with fetal lung maturity
  • Slippery lipoprotein acts to reduce surface tension within the alveoli allowing the alveoli to remain partially open with breathing
  • Without surfactant, the alveoli collapse with exhalation and must be reopened with each new breath increasing the respiratory workload
  • Fetal breathing movements
  • Movements develop the chest wall muscles and the diaphragm
  • Converts from a fluid-filled to a gas-filled organ
  • Breathing movements are essential for developing the chest wall muscles and the diaphragm and to a lesser extent, for regulating lung fluid volume and resultant lung growth.
  • Breathing
  • Initiation of Breathing (pg 564)
  • Mechanical Events
  • Increased intrathoracic pressure - as chest is
  • squeezed removes fluid from lungs
  • Negative intrathoracic pressure - after birth, chest
  • recoils producing a small passive inspiration of air
  • Positive intrathoracic pressure - newborn
  • exhales crying with a partially closed glottis
  • Chemical Stimuli
  • Transitory asphyxia stimulates CNS response
  • triggered by increased PCO2 and a decreased pH and PO2
  • This is called Respiratory Acidosis
  • Thermal Stimuli
  • Stimulation of skin nerve endings
  • Temperature decreases from 98.6 to 70 – 75 degrees F
  • If temperature drops too low, respirations are depressed
  • Sensory Stimuli
  • Moves from a familiar, comfortable, quiet environment to one of sensory abundance – tactile, auditory, and visual stimuli
  • Thorough drying of the baby provides sufficient stimuli
  • Factors Opposing the First Breath
  • Alveolar surface tension – surfactant reduces surface tension, prevents alveoli from collapsing
  • Viscosity of lung fluid
  • Degree of lung compliance – ability of lungs to fill with air
  • Highlights from Respiratory
  • The production of surfactant is crucial
  • Newborn respiration is initiated primarily by chemical and mechanical events, in association with thermal and sensory stimulation.
  • The newborn is an obligatory nose breather
  • Normal respiratory rate is 30 to 60 breaths per minute
  • Periodic breathing is normal, and newborn sleep states affect breathing patterns
  • Cardiopulmonary Adaptations
  • Info
  • Increased aortic pressure and
  • decreased venous pressure
  • Increased systemic pressure and
  • decreased pulmonary artery pressure
  • Closure of the foramen ovale
  • Closure of the ductusarteriosus
  • Closure of the ductusvenosus
  • Oxygenated blood leaves the placenta and enters the fetus through the umbilical vein.
  • After circulating through the fetus, deoxygenated blood returns to the placenta through the umbilical arteries.
  • The ductusvenosus, the foramen ovale, and the ductusarteriosus allow the blood to bypass the fetal liver and lungs.
  • Fetal Circulatory System *See handout she gave us and also pg 66)
  • DuctusVenosus
  • Foramen Ovale
  • DuctusArteriosus
  • The shunts ensure that most of the blood supply bypasses the fetal lungs. The placenta is supplying oxygen and removing fetal carbon dioxide
  • Characteristics of Cardiopulmonary Physiology
  • Air enters the lungs; increased PO2 stimulates relaxation of the pulmonary arteries and a decrease in pulmonary vascular resistance; Vascular flow (circulation) in the lungs increases.
  • Pulmonary circulation distributes blood throughout the lungs to pick up O2/exchange Co2.
  • Increased blood flow to lungs contribute to conversion from fetal circulation to newborn circulation
  • Blood Pressure
  • Highest immediately after birth and decreases 3 hours after birth; days 4-6 plateaus at original level
  • Capillary refill is indicator of peripheral perfusion. Should be 2-3 seconds
  • Normal BP varies according to birth weight
  • Check BP in all 4 extremities with initial assessment of a newborn
  • Crying causes an increase in both systolic and diastolic BP
  • See pg 569 Figure 23-3
  • Comparing Fetal and Neonatal Circulation
  • Fetal
  • Pulmonary blood vessels constricted; lungs fluid-filled
  • Systemic blood vessels dilated
  • Ductusarteriosus large with blood flow from pulmonary artery to aorta
  • Foramen ovalepatent with flow from R to L atrium
  • Neonatal
  • Pulmonary blood vessels vasodilated with increased blood flow
  • Systemic blood vessels constricted - BP rises
  • Ductus begins to constrict; blood flow from aorta to pulmonary artery
  • Foramen ovale is closing due to increased pressure in L atrium
  • Heart Rate
  • At birth with first cry HR=175-180
  • Full-term newborn HR=120-160 depending on activity level
  • Assess apical pulse for 60 seconds with the infant asleep
  • Assess PMI, regularity, presence of murmurs
  • Assess peripheral pulses for strength & equality
  • Heart Murmurs/Defects
  • Heart Murmurs
  • Extra sound produced by blood flow in the heart or great vessels
  • 90% of murmurs heard in the newborn are transient
  • Heart defects
  • Murmur can be present or absent
  • Right-sided defects better tolerated that left-sided defects
  • Cardiopulmonary function in some malformed hearts may become compromised when shunts close.
  • Cardiovascular Highlights
  • The status of the cardiopulmonary system may be measured by evaluating the heart rate, blood pressure, and presence or absence of murmurs
  • The normal heart rate is 120 to 160 beats per minute
  • Normal capillary refill is 2-3 seconds
  • Hematopoietic Adaptations
  • Physiologic Anemia of Infancy
  • Normal Newborn has higher hgbhct with larger RBCs than older children or adults
  • Transient increase in hgbhct occurs
  • If placental to infant transfusion occurred
  • Low oral intake & diminished extracellular fluid volume
  • Hemoglobin level declines over the first 2-3 months of life
  • Cessation of erythropoiesis with SaO2 increase at birth
  • Expansion of blood volume accompanying rapid growth
  • At 2-3 months of age erythropoiesis resumes
  • Factors Affecting Blood Volume
  • Blood volume is approximately 80-85 ml/kg of body weight
  • Delayed cord clamping
  • Gestational age
  • Prenatal and/or perinatal hemorrhage
  • Site of the blood sample
  • Leukocytosis
  • Increased neutrophilproduction results from the stress of birth
  • By 2 weeks neutrophils decrease to 35% of total WBC count
  • Lymphocytes become predominant and WBC total decreases
  • Highlights on Hematopoietic System
  • See page 570 Table 23-2
  • Normal Term Newborn Blood Values
  • Blood values in the newborn are modified by several factors, such as site of the blood sample, gestational age, prenatal and/or perinatal hemorrhage, and the timing of the clamping of the umbilical cord
  • Temperature Regulation
  • Heat Loss from Body Surface to Environment *see pg 572 Figure 23-5*
  • Convection
  • The loss of heat from the warm body surface to the cooler air currents. Examples: air conditioned rooms, air currents with a terperature below the infant’s skin temperature, oxygen by mask, and removal from an incubator for procedures.
  • Radiation
  • When heat transfers from the body surfact to cooler surfaces and objcts not in direct contact with the body. Examples: the walls of a room or an iancubator; placing cold objects onto the incubator or near the infant in the radiant warmer
  • Evaporation
  • The loss of heat when water in converted to a vapor. Example: a newborn wet with amniotic fluid and blood, during baths.
  • Conduction
  • The loss of heat to a cooler surface by direct skin contact. Example chilled hands, cool scales, cold exam tables, a cold stethoscope
  • Thermoregulation
  • Thermoregulation occurs when oxygen consumption and metabolic activity are minimal
  • The baby isn’t having to burn up their fat to warm themselves
  • Newborns transfer heat from internal core to the body surface
  • Thermal Neutral Zone
  • Thermal Neutral Zone: Environmental temperature range where the internal body temperature is maintained and the rate of O2 consumption and metabolism are minimal
  • The room is the right temperature so that they don’t have to burn fat to warm themselves
  • Newborns require higher environmental temperatures for their thermal neutral zone
  • NonshiveringThermogenesis
  • Unique to Newborns
  • Occurs to provide heat in the cold-stressed newborn
  • Regulated by the sympathetic nervous system
  • Brown fat is metabolized to generate heat
  • Brown fat is unique to the newborn, it’s brown because it’s so highly vascular, it transfers the heat it’s holding to the baby
  • Rationale for Increased Heat Loss
  • Decreased subcutaneous fat
  • Thin epidermis
  • Blood vessels close to the skin
  • Hazards of Cold Stress
  • Increased O2 consumption
  • Respiratory distress
  • Use of glycogen stores
  • Hypoglycemia
  • Metabolizing brown fat
  • Decreased surfactant production
  • Metabolic acidosis
  • Byproduct of burning fat to keep warm
  • Eventually leads to respiratory acidosis
  • Jaundice
  • Highlights of Temperature Regulation
  • Heat conservation is enhanced by flexed posture because the skin’s surface area exposed to the environment is decreased
  • They ball up or whatever, this reduces surface area, pull their arms in and what not
  • Flexed posture isn’t heat loss or the inability to lose heat, it has to do with conserving their heat or keeping it in!
  • Evaporation is the primary heat loss mechanism in newborns who are wet
  • Excessive heat loss occurs from radiation and convection because of the newborn’s larger surface area compared with weight
  • The primary source of heat in the cold-stressed newborn is brown adipose tissue
  • Important to keep baby warm because if it is cold stressed it can send them into acidosis (metabolic and respiratory), can cause hypoglycemia
  • Hepatic Adaptation
  • Newborn Liver Functions
  • Iron storage and RBC Production
  • As RBCs are destroyed after birth, the iron is stored in the liver until needed for new RBC production
  • Infant has iron stores from mother for about 5 months
  • After 5 months, will need iron supplement to prevent anemia
  • Carbohydrate metabolism
  • Glucose is supplied by the placenta until birth
  • Newborn carbohydrate reserves are limited
  • Metabolic fuel sources are consumed by the work of breathing, heat production, and activation of muscle tone
  • Glucose is main source of energy in the first 4 to 6 hours
  • As stores of glycogen and blood glucose decrease the newborn changes to fat metabolism
  • Conjugation of bilirubin
  • Unconjugatedbilirubin is a breakdown product of destroyed RBC’s - indirect bilirubin
  • Unconjucated is lipid soluble, and we can’t get these out of our body. Conjugated is water soluble, so we can get rid of it
  • Conjugation of bilirubin must occur for elimination to occur (conversion of yellow lipid soluble pigment into water-soluble pigment) - direct bilirubin.
  • The newborn’s liver must conjugate bilirubin after birth
  • Coagulation
  • Coagulation factors II, VII, IX, and X are synthesized in the liver and are activated by Vitamin K
  • Vit K is made in our bodies by bacteria in the intestines, when the baby is born their gut is sterile, they don’t have the ability to make vit K so we give it to them, if they don’t get it they may have bleeding problems
  • There is an absence of normal flora to synthesize Vitamin K in the newborn gut
  • Vitamin K given IM at birth to prevent potential bleeding problems
  • Jaundice
  • Jaundice is a yellowish coloration of the skin and sclera of the eyes that develops from deposit of the yellow pigment Bilirubin in tissues.
  • 3 Types of Jaundice in the Newborn
  • Physiologic
  • Occurs after the first 24 hour of life
  • Bilirubin level does not exceed 5 mg/dl/day or 15 mg/dl in first week of life
  • Normal bilirubin level is 1-2.2 ish…
  • Bilirubin peaks at 3 to 5 days
  • Occurs not from pathology but as a normal biologic response of the newborn to
  • Hemolysis of excessive erythrocytes
  • Short RBC life
  • Pathologic
  • Occurs in the first 24 hours
  • Caused by excessive destruction of RBCs, infection, or maternal-fetal blood incompatibilities
  • Bilirubin rises rapidly in response to the disease process and can cause significant problems
  • Breastfeeding
  • Occurs when bilirubin rises about the fourth day after mature breast milk comes in (higher concentration of fatty acids in the breast milk)
  • Peaks at 2 to 3 weeks of age
  • Occurs in response to breastmilk’s higher concentration of free fatty acids which compete with bilirubin for binding sites
  • Interruption of breastfeeding for 24 hours is usually recommended
  • Nursing Care for Jaundice
  • Maintain skin temp at 97.8F (36.5C)
  • Encourage early feeding to promote intestinal elimination and bacterial colonization and provide caloric intake
  • Keep newborn well hydrated and promote intestinal elimination
  • Because it’s under a light (phototherapy), it’s like when you’re out in the sun all day
  • Phototherapy if bilirubin exceeds normal for age level
  • Gastrointestinal Adaptations
  • Characteristics
  • The full-term newborn can digest simple carbohydrate, proteins, and fats
  • Stomach capacity of about 50-60 ml and empties 2 to 4 hours after feeding
  • Cardiac sphincter and stomach’s neural control are immature
  • Regurgitation (sometimes excessive) may be noted in the first few days. Should be small amount and decrease
  • Growth and Development
  • Postnatal growth should parallel intrauterine growth (30 g/day) (or an ounce)
  • Requires 120 cal/kg/day
  • Initial weight loss of 5-10% is normal
  • Say you have a baby that weighs 6lb 8oz you would convert it all to oz or grams then take away the 5-10%.... She will have a question like this on the test!
  • Elimination
  • First bowel movements occur within 24 hours and consist of meconium
  • Meconium thick black or dark green stool that is formed in utero from amniotic fluid, intestinal secretions, and mucosal cells.
  • Transitional stools replace meconium gradually
  • Thin brown to green consisting of meconium and fecal material
  • Breast/Formula Feeding *see pg 578 Figure 23-8*
  • Breast Milk Stools
  • Yellow-gold or green
  • Soft or mushy
  • More frequent at first
  • Formula Milk Stools
  • Paler yellow than breast
  • Formed or pasty
  • Frequency varies
  • Urinary Adaptations
  • Info
  • Newborns are less able to concentrate urine because the renal tubules are short and narrow.
  • The effect of excessive insensible water loss or restricted fluid intake is unpredictable
  • Characteristics
  • Concentrating and dilutional limitations of renal function due to:
  • Decreased rate of glomerular flow
  • Limited excretion of solutes
  • We have to be careful with drugs that are nephrotoxic because they can’t excrete them as well
  • Limited ability to concentrate urine
  • Must monitor fluid therapy to prevent dehydration or over-hydration
  • Urinary Functions
  • Many newborns void immediately after birth & voiding should be noted
  • 93% void in 24 hours; 98% void by 48 hours
  • Bladder capacity 6 to 44 ml of urine
  • First 48 hours urine output=15 ml/day
  • Urine output should then increase to 25ml/kg/day
  • Urinary Values
  • Normal early urine may be cloudy due to mucous or have pink staining on diaper due to urates
  • Female infants may have pseudomenstruation
  • A bloody discharge in response to withdrawal of maternal hormones
  • Immunologic Adaptations
  • Characteristics
  • Newborn immune system not fully activated
  • Lack of inflammatory response results in subtle non-specific signs/symptoms of infection
  • Poor hypothalamic response to pyrogens
  • Fever not a reliable indicator of illness
  • Sick newborn more likely to be hypothermic
  • IgG
  • Crosses placenta and confers passive immunity to infant in response to maternal illness or immunization
  • Transferred during 3rd trimester giving newborn passive immunity to tetanus, diphtheria, smallpox, measles, mumps, polio, and other bacterial or viral diseases
  • Variable duration of immunity from 4 weeks to 8 months so immunizations are begun at 2 months to develop active acquired immunity
  • IgA
  • Provides protection on secreting surfaces such as respiratory tract, gastrointestinal tract, and eyes
  • Does not cross the placenta
  • Colostrum is high in IgA possibly providing passive immunity to breastfed newborns
  • IgM
  • Produced in response to blood group antigens, gram-negative enteric organisms, and some viruses in the expectant mothers.
  • Does not normally cross the placenta accounting for the newborn’s susceptibility to gram-negative enteric organisms (i.e. E. Coli)
  • Elevated levels at birth indicate placental leaks or antigenic stimulation in utero (i.e. TORCH or syphilis)
  • TORCH stands for several different infections, like T is toxoplasmosis, H is for herpes, etc.
  • If you see an elevated IgM in the newborn it is bad because it means it was exposed
  • Neurologic and Sensory-Perceptual Functioning
  • Characteristics
  • Newborn brain is ¼ adult size and myelination of nerve fibers is incomplete
  • The brain and nervous system structures mature in a predictable order
  • Partially flexed extremities with legs near the abdomen with random, uncoordinated movements of the extremities
  • Eyes – able to fixate on faces/objects and blinks reflexively to bright light
  • Growth progresses in cephalo-caudal manner (head-to-toe)
  • Muscle tone is symmetrical and hypertonic
  • Predictable reflexes are present
  • Displays some complex behavioral patterns – hand to mouth demonstrates motor coordination and self-quieting
  • The First Period of Reactivity
  • Lasts for 30 minutes after birth.
  • Newborn is alert and eager to breastfeed
  • May have tachycardia/tachypnea; mildly increased respiratory effort
  • Sleep phase then lasts up to 4 hours
  • Second Period of Reactivity
  • Awake/alert for 4 to 6 hours
  • Increased heart and respiratory rates
  • Apnea and bradycardiamay occur
  • Color fluctuations
  • Increased respiratory and gastric mucous and may gag, choke, or regurgitate
  • Gastrointestinal tract becomes more active
  • Behavioral States
  • Sleep States
  • Deep or quiet sleep-eyes closed with no movement; regular breathing; subdued startles; 35-45% of total sleep
  • Active REM sleep- eyes closed with eye movements visible; irregular breathing; irregular sucking; startles responsively to environmental or internal stimuli; 45-50% of total sleep
  • Alert States
  • Drowsy or semi-drowsy
  • Active awake
  • Hyper alert/Crying
  • Behavioral Capacities
  • Important to support infant in achieving a robust sleep or quiet alert state for optimum growth, development, and bonding
  • Habituation: Ability to process and respond to visual and auditory stimulation, then with repeated stimulation the newborn’s response diminishes
  • Orientation: Ability to alert to, follow, and fixate on complex visual stimuli. Useful in becoming familiar with family, friends, and surroundings
  • Self-quieting: Ability to quiet and comfort self
  • Sensory Capacities
  • Auditory: Responds with increased heart rate, startle, or alerting. May search for the source
  • Olfactory: Newborns can select people by smell; mom’s breastmilk
  • Tactile: Sensitive to being touched, cuddled, and held
  • Taste and Sucking: Responds differently to varying tastes. Breastfeeding produces different kind of sucking than bottle-feeding