Physiological Adaptations of the Newborn Flashcards
First period of reactivity (physiological adaptation has three stages - all three stages occur during the first 6-8 hours. Stages are mediated by the CNS - HR, Resps, Temp, GI function
- insides are adapting to new environment. Baby is extremely stimulated.
- lasts up to 30 minutes after birth
- Newborn’s HR increases to 160 to 180 beats/min
- Respirations may be irregular: 60 to 80 breaths/min (there may be fine crackles b/c of fluid that was in the lungs, grunting, nasal flaring, retractions)
- Baby is alert, spontaneous startle reflex, tremors, crying, movement of head
- Bowel sounds present, may pass meconium
- Followed by a decrease in motor activity and sleep
Second stage: Period of decreased responsiveness
- baby is exhausted. Baby’s can handle 20 minutes of activity then it will shut down
- lasts 60 - 100 minutes
Stage 3: Second period of reactivity
- occur 2 to 8 hours after birth
-lasts 10 minutes to several hours - baby should want to feed and interact
- tachycardia, tachypnea may occur
- meconium commonly passed
- increased muscle tone, changes in skin colour, and mucus production
Respiratory System - Pink
- initiation of breathing and maintaining adequate oxygen supply
- cord clamped and cut - rapid physiologic changes. establishment of spontaneous resps. Prems - problems d/t immature lungs & gestational age
- in utero - transplacental gas exchange with fetal blood shunted away from lungs. clamping cord rise in BP - increases circulation and lung perfusion. -
initiation of resps d/t chemical, mechanical, thermal and sensory factors - chemical factors
- mechanical factors
- thermal
- sensory
chemical factors of respiration
neonate assume responsibility for all gas exchange and metabolism.
- decreased levels of oxygen and increases levels of CO2 stimulate resp center in medulla
Mechanical factors initiation resps
- intrathoracic pressure changes as circulatory system becomes independent. results from compression of chest during vag birth. neg intrathoracic pressure helps draw air into the lungs. Crying increases distribution of air into lungs and promotes expansion of alveoli. positive pressure keeps alveoli open.
- alveoli - type I and II make surfactant which reduces surface tension required to keep alveoli open preventing total alveolar collapse on exhalation
Thermal factors
initialization of breathing
- exposure to air tempt stimulates receptors in the skin leads to stim of resp center
Sensory factors
handling, drying infant, lights, smells, sounds
- preceding labour: decreased production of fetal lung fluid and decreased alveolar fluid. Just before labour there is a catecholamine surge which seems to promote clearance from the lungs.
Signs of respiratory distress - from retention of lung fluid
- Fluid retention more likely in a C/S delivery
- Remember neonates may have irregularities in breathing at first
- Respiratory distress = nasal flaring, intercostal or subcostal retractions
- evaluated RR < 30/min or > 60/min
- Central cyanosis is a late sign of distress (lips & mucous membranes blueish)
Transient Tachypnea of the Newborn
- respiratory problem that can be seen in the newborn shortly after delivery
- retained fetal lung fluid due to impaired clearance mechanisms
- diagnosed in the first few hours
- transient means it does not last long (usually, less than 24 hours) and tachypnea refers to the baby’s faster-than-normal breathing (more than 60 breaths/min)
- supplement with oxygen or ventilator support
Clearing mechanisms (coughing, crying, BF)
Cardiovascular System
- pulmonary artery pressure decreased and pressure to right atrium decreased
- increased pulmonary blood flow and closure of the foramen ovale (normal opening between atria that closes at 6 months)
- Ductus Arteriosus: constricts with increased oxygen and prostaglandin (ductus arteriosus is a normal fetal vessel between cardiac and pulmonary systems that closes in 2-3 days). closes within first hours, permanently closes within 3-4 weeks. becomes ligament. it can reopen in response to low oxygen levels.
- Heart rate and sounds - apical. BP = 60-80 systolic/ 40-50 diastolic. variations in 1st month
- Blood Volume = 300 mL (not a lot - take bruising more seriously) (can increase by 100mL depending on length of time the cord clamping and cutting. Prem > bl volume d/t greater plasma volume (not greater RBC)
Signs of cardiovascular problems - murmur, cyanosis, pallor with murmur
- persistent tachycardia (> 160 bpm) due to anemia, hypovolemia, hyperthermia, sepsis
- persistent bradycardia (< 100 bpm due to congenital heart block, hypoxemia, hypothermia)
Hematopoietic system: RBC
- RBC (4.8-7.1x10^12/L) and hemoglobin (137-201g/L) are increased b/c fetal circul is less efficient at oxygen exchange than the lungs so fetus needs additional RBC for transport of O2 in utero. At birth, average levels of RBC and Hgb are higher than in an adult. Levels drug over 1st month
Hematopoietic System: Leukocytes, Platelets, Blood group
Leukocytes: increase during 1st day and then decrease rapidly. going to have to start building their own immune system after they stop getting it from their mom
Platelets: newborns are the same as adults except platelet factors in the liver in first days of life mean newborns cannot synthesize vit K. injection given to assist with clotting
Blood group: is determined via cord blood samples along with potential for hyperbilirubinemia (bilirubin is product of RBC breakdown and neonates cannot get rid of it easily)
Thermogenic System - heat regulation WARM
Thermal regulation:
the balance of heat production and loss
- conserve heat in position of flexion to guard against heat loss (diminishes body surface exposed to environment. Also vasoconstriction of peripheral BV
Heat Loss
Convection
Radiation
Evaporation
Conduction
Heat loss: heat transfer from newborn to environment
- hypothermia: common d/t thin layer of subcutaneous fat and blood vessels are close to skin surface. also changes in environmental temp alter temp of blood & influence temp regulation. center in hypothalamus. newborns have larger surface to wt. mass ratio = heat loss quickly
Convection: flow of heat from body surface to cooler ambient air (need warmer ambient temps, use overhead warmers), wrap baby in blanket, hats (in in open bassinets)
Radiation: loss of heat from body surface to cooler not in direct contact with newborn (position exam tables, bassinets away form open windows or direct air drafts)
Evaporation: loss of heat when liquid converted to vapour. (moisture vaporization from skin - be sure to dry skin of newborn after birth/bath quickly. the less mature the more evaporative heat loss)
conduction: heat loss from body surface to cooler surface
Thermogenesis
internal attempts to generate heat (cellular metabolic activity in brain, heart and liver increases oxygen and glucose consumption.
- heat loss will make baby very tired and withdrawn
thermogenesis: brown fat
non-shivering thermogenesis occurs through the metabolism of brown fat
- located in interscapular region, axillae, thoracic inlet, vertebral column, around kidneys
- amount increased with gestational age
Babies dont have a lot of brown fat
Cold stress
- increased RR with oxygen needs. Leads to vasoconstriction - can decrease pulmonary perfusion - reopen R to L shut across ductus arteriosis
Hyperthermia
- Temp > 37.5 due to excess heat production or sepsis (radiant warmers, phototherapy, sunlight, increased environmental temp, excess clothing - vasoconstriction)
physiological adaptations of the Newborn Impact of Temperature
cold -> increased O2 consumption -> increased resp rate -> pulmonary vasoconstriction -> decreased O2 uptake by lungs
increased resp rate -> peripheral vasoconstriction -> decreased O2 to tissues -> increased anaerobic glycolysis -> decreased PO2 and pH -> metabolic acidosis
Renal System
Most newborns void at birth (can be missed)
1st day - 1 void
2nd day - 2 voids
3rd day - 3 voids
1 weeks - 6-8 voids
5-10% wt loss in 1st 3-5 days is normal d/t urine, feces, lungs, increased metabolic rate, intake (colostrum is high fat but not high volume)
- uric acid crystal stains can occur, watch for persistence
- Fluid and electrolyte balance (75% body wt. total body water - extracellular and intracellular)
- daily fluid intake requirements
- lower GFR with less ability to remove nitrogenous & waste products from blood
