Sept17 A2-prematurity Flashcards
(30 cards)
prematurity def
born at less than 37 completed weeks
-note: threshold of viability is 22-25
prematurity classifications
- by weight
- by gestational age
classif by weight
- low birth weight = <2500g
- very LBW (VLBW) = <1500g
- extremely LBW (ELBW) = <1000g
classif by gestational age
- extreme premature = <28 wks
- late pre term = 34 to 36.85
- weight AGA (appropriate for gestational age)
- weight LGA (large for gest age): above 90th percentile
- wieght SGA (small for gest age): below 90th percentile
intra uterine growth restriction def (IUGR)
- NOT SGA
- process limiting fetus from achieving full growth potential
- either symmetric or asymmetric (head also small = symmetric. body small compared to head = asymmetric)
reasons for premature birth
- medical risk factors
- environmental risk factors
medical RFs
- maternal (Age, prior preterm birth, chronic illness, clotting disorder)
- anatomical (cervical or uterine)
- pacental
- infection
- fetal
environmental RFs
- smoking
- alcohol
- drugs
- poor prenatal care
- low maternal education and SES
- malnutrition
(IMP?) main risks for a premature baby in the first 24 hours
- hypothermia
- dehydration
- respiratory distress syndrome (RDS) (thing about alveoli surfactant)
- hypoglycemia
why hypothermia in premature newborns
- born wet
- cold environment
- high surface to body volume ratio
- insufficient brown fat stores (for thermogenesisi)
- porous skin
- less fat insulation
forms of heat loss in premature baby hypothermia
- radiation (normal loss of EM radiation to colder usrroundings) = avoid cold delivery room, keep in isolette or use radiant warmer)
- conduction: loss of heat by contact with colder object = use warm blankets, had, warm surface
- convection = loss of heat by contact with colder air current = avoid cold drafts and keep in isolette)
- evaporation (loss of heat by conversion of water to apor at skin surface ) = keep high humidity in the closed isolette, put infant in plastic bag if <32 weeks
causes of premature baby dehydration
- transepidermal water loss (insensible = not measurable) bc of high surface-volume ratio and less keratinization of skin
- resp tract (insensible)
- urinary (sensible): immature renal fct, reduced ability to reabsorb water and Na
how to prevnent dehydration of premature
- humidified air in isolette and when ventilate
- IV fluids for all infants under 34 wks
what are the signs of RDS (or HMD = hyaline membrane disease)
- tachypnea (90 RR)
- grunting (expiring against close epiglottis to increase FRC)
- nasal flaring
- needs 40% O2
- see intercostal spaces
cause of RDS
relative deficiency in surfactant (produced by alveolar type 2 pneumocytes as of 24 wks, mature levels at 35). surfactant reduces surface tension in alveolar-air interface so easier to inflate alveoli
consequences of surfactant deficiency in RDS (what leads to sx)
- reduced lung compliance (lower tidal volume, higher pCO2, tachypneic)
- reduced FRC (atelectasis, VQ mismatch bc of atelectasis, increased O2 needs therefore. + grunting)
definitive tx or RDS
- intubate (mechanical ventilation)
- exogenous surfactant administration
- before this, can support with IV fluids, O2 and CPAP*
normal glucose in the neonate
2.6 mmol per L and more
sx of hypoglycemia in premature neonate
- tachypnea
- irritability
- jitteriness
- hypotonia
- lethargy
- convulsion
causes of hypoglycemia in premature neonate
- increased energy demand (resp, thermoregulation, cerebral metab)
- reduced stores (less glycogen in muscles and liver)
- insufficient gluconeogenesis
what is breath holding spell
TERM baby stops breathing on occasion
what is apnea of prematurity
- baby stops breathing on occasion, desatures to 70% and bradycardia to 80s
- need to stim to breathe again
caution about apnea of prematurity
IS A DIAGNOSIS OF EXCLUSION
- not always benign
- search for other problems like hypoglycemia, sepsis that can also cause apnea before saying apnea of prematurity
causes of apnea of prematurity
- central (decreased resp drive and response to chemoreceptors)
- obstructive (collapse of airways due to lack of pharyngeal muscle tone)
- mix of both
