NEONATAL RESUSCITATION EXTREME PREMATURITY
Category: Child Health
Abstract : Extreme prematurity Premature infants have special needs that must be
considered during the critical period immediately following delivery if
mortality and morbidity are to be decreased in this group. This population of
infants is at increased risk for respiratory failure, insensible water losses,
hypoglycemia, and intraventricular hemorrhages. It is impossible to adequately
review th
Extreme prematurity
Premature infants have special needs that must be
considered during the critical period immediately following delivery if
mortality and morbidity are to be decreased in this group. This population of
infants is at increased risk for respiratory failure, insensible water losses,
hypoglycemia, and intraventricular hemorrhages.
It is impossible to adequately
review the many difficulties of extreme prematurity in this section, but special
concerns regarding the care of these infants during the resuscitation period is
discussed.
Insensible water loss in the premature infant is increased
secondary to the infant's poorly cornified epidermis and an immature stratum
corneum, which presents little barrier to evaporative heat loss. The stratum
corneum is not functionally mature until 32-34 weeks' gestation. Differences in
skin maturity, prenatal nutritional status, ventilation requirements, and
environmental conditions all may influence the magnitude of insensible water
loss that occurs following birth.
The skin is the most important route
for water depletion after delivery of the extremely immature infant.
Transepidermal water loss (TEWL) is highest at birth in infants who are born
before 28 weeks' gestation and decreases slowly with advancing gestational age.
Despite declines in TEWL with advancing age, infants born before 28 weeks'
gestation continue to have increased TEWL for 4-5 weeks following birth,
compared to infants born at term. Because of high evaporative loss with the
accompanying heat loss, the ability to achieve and maintain thermoregulation is
compromised further. The skin barrier dysfunction increases the risk for
infection, especially because of organisms that colonize the skin surface (eg,
staphylococcal species). This thin skin barrier also places the extremely
immature infant at risk for toxicities from topically applied substances.
Additionally, skin integrity is disrupted easily by the use of adhesives, which
should be limited in premature infants.
Premature infants need increased
fluid administration rates initially if they are on radiant warmers for a
prolonged period. With increased parenteral fluid administration using
dextrose-containing fluids, the dextrose needs to be monitored closely to ensure
euglycemia. Placing infants in a humidified environment decreases transepidermal
water loss, improves the maintenance of body temperature, and does not delay
skin maturation. Measures to decrease insensible water loss should be initiated
at delivery. Because radiant warmers are used routinely at deliveries because of
a need for maximal patient access, infants less than 1000 g should have a
plastic blanket or other barrier applied to decrease evaporative water loss
until they can be placed in a humidified environment. However, care should be
taken to ensure that the barrier does not block the transmission of the radiant
heat source. Premature infants are at risk for intraventricular hemorrhages and
periventricular leukomalacia (PVL) secondary to their immature cerebral vascular
regulation and the persistence of the germinal matrix. Ventricular hemorrhage
and periventricular leukomalacia often lead to serious permanent
neurodevelopmental disabilities. Prevention or reduction of the severity of
these disorders may begin in the delivery room. Mechanical ventilation and fluid
administration must be managed cautiously in this group of infants. Volume
expansion should only be administered in the face of true hypotension. It is
essential to know normal blood pressure values for infants of various
gestational ages. Volume expansion in the face of normal blood pressure
increases the risk of IVH.
Additionally, when administering hyperosmolar
medications (eg, sodium bicarbonate), slow administration is important.
Mechanical ventilation may lead to harmful fluctuations in cerebral blood flow,
especially when pCO2 and pH are altered rapidly. Rapid alterations in pCO2 and
pH result in acute fluctuations in the cerebral blood flow of the premature
infant with immature cerebral vascular autoregulation.
Premature infants
are also at high risk for volutrauma caused by poor lung compliance and
overventilation following the administration of exogenous surfactants if changes
in lung compliance are not monitored carefully. Overventilation with excessive
tidal volumes and hypocarbia are associated with chronic lung disease.
Stabilization of the infant using the lowest possible peak inspiratory pressures
that are required to oxygenate and ventilate adequately is essential. Hand
ventilation of an intubated infant, especially by inexperienced personnel, often
leads to inconsistent tidal volumes and pressures. Use of a mechanical
ventilator designed for infants offers the advantages of more consistent tidal
volumes and a reduction of the heat losses because of the use of unheated
nonhumidified air with hand bagging.
Although artificial surfactant
administration is associated with a reduction of adverse sequelae in infants,
its administration may lead to hyperventilation and overdistension when not
administered by experienced attentive personnel. Following the instillation of
artificial surfactant, rapid reaction to changes in pulmonary compliance to
prevent the onset of hypocarbia and alkalosis is essential. Following the
institution of mechanical ventilation, care should be taken with airway
suctioning because vigorous or frequent airway suctioning is associated with
hypoxia, intraventricular hemorrhage, and periventricular leukomalacia.
Prematurity with respiratory distress syndrome (RDS) is not associated with
mucous production in the first 24 hours of life, thus suctioning protocols
should be altered to provide minimal suctioning during this time.
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