Infant Respiratory Distress Syndrome
The past decade has witnessed a
decrease in premature infant. To a great extent this has been due to the
development in neonatology. A decline in the rate of premature infant deaths
has been noted in the area of infants suffering respiratory distress syndrome [1].
To begin the discussion, an understanding of what infant respiratory distress
syndrome is, is important. The term refers to a syndrome affecting premature
infants. The syndrome is believed to be caused by surfactant production’s
developmental insufficiency as well as structural immaturity of the lings. The
syndrome can be caused by problem in the generation of surfactant associated
proteins. This problem can be genetic in nature. Infant respiratory distress
syndrome affects approximately 1 percent of infants and has been known to be
one of the leading causes of death in premature infants [2].
Etiology
Production of surfactant is not sufficient early in
gestation until later. This means that risk of developing respiratory distress
syndrome is greater with prematurely. The chances of developing this syndrome
decreases with the increase in gestational age of the infant, from
approximately 50 percent in infants born between 26 and 28 weeks, to
approximately 25 percent in those between 30 and 31 weeks [3].
Infant respiratory distress syndrome is more frequent in infants with diabetic
mothers and well as in second born of twins born prematurely. Other risk
factors include multifetal pregnancies, as well as being male and white. Risk
of developing respiratory distress syndrome decreases with fetal development
limitation, eclampsia or preeclampsia, prolonged rupture of membranes, maternal
hypertension, and maternal corticosteroid use. Few cases of respiratory
distress syndrome are genetic, as a result of mutations in “surfactant protein (SP-B and SP-C) and ATP-binding cassette transporter A3
(ABCA3) genes [2].”
In infant, etiology could differ on
the basis of the time when the distress began, or rather the onset of the
distress. Incase the infant has tachypnea starting at birth it could be caused
by TTNB or resulting to polycythemia. Incase the distress begins early but it
is more serious it may be caused by MAS, asphyxia, pneumonia, or malformations.
Incase the distress is diagnosed at the end of one week after birth or later,
it can be as a result of pneumonia. Additionally, a cleft palate, and history
of choking incidents can show aspiration pheumonia. Nevertheless, if the infant
has hepatomegaly, or incase the infant is experiencing a shock, a cardiac cause
can be considered. Alternatively incase the infant is experiencing dehydration
there is the likelihood of metabolic acidosis [5].
Management techniques
and related complications
Supportive therapy is important in
all infants diagnosed with respiratory distress syndrome. Whatever the real or
possible cause of the distress, the same principle applies. The importance of
monitoring is stressed in all children suffering from respiratory distress
syndrome. Clinical monitoring is vital as there are sophisticated devices
available for this purpose. The use of the scoring system is advocated to
monitor the condition of the infant, where an increasing score would reveal
that his or her condition is becoming worse [5]. Various treatment
procedures that can be used depending with various conditions associated with
the distress are available:
Oxygen therapy
Incase only a mild level of
respiratory distress syndrome is diagnosed at birth, the infant can be put in
an oxygen hood. This is enough treatment for children who are not severely
affected. All children suffering from respiratory distress syndrome should be
provided with oxygen. The oxygen should be humidified and warm. The oxygen can
be supplied through an oxygen hood or through a nasal catheter. The rate of
flow of the oxygen ought to be 2-5 L/min [6].
Possible complications
of oxygen hood
While the child is under treatment
through the use of an oxygen hood, there is the possibility of too much oxygen
being pumped in. this can cause damage to the retina, which can lead to loss of
vision. In the 1950s, the harmful effects of the use of oxygen were revealed
when loss of eye sight occurred in infants supplied with pure oxygen. An
oximeter can be used to keep track of the amount of oxygen being pumped in.
this is important in avoiding other complications like repeated artery
punctures or heel sticks. It is also important to note that oxygen can be toxic
and should therefore be administered if need be [7].
Intratracheal surfactant therapy
In cases of respiratory distress
syndrome that are more severe, a drugs like Exosurf Neonatal or Survanta
(natural surfactant) can be seeped into the lungs of the infant. The drug is
dripped through an endotracheal tube, which is a fine tube inserted into the
windpipe (trachea) of the infant. This may also be required to achieve
sufficient oxygenation and ventilation. The surfactant used is either synthetic
of obtained from the lungs of an animal. Survanta a commonly known surfactant
is obtained from the lungs of a cow. In most cases, the infant is in a position
to breathe with no trouble within a few days. The use of the drug lowers the
possibility of lung rapture. The use of the drug is continuous until the point
where the infant begins to generate surfactant.
Drugs used to stimulate breathing can be used in speeding up the
treatment and recovery process. Surfactant speeds up recovery as well as
decreasing the risk of “pneumothorax, interstitial emphysema, intraventricular
hemorrhage, bronchopulmonary dysplasia, and neonatal mortality in the hospital
and at 1 yr 2].” alternatives for surfactant substitute include
beractant. This
is a “lipid bovine lung extract supplemented with proteins B and C, colfosceril
palmitate, palmitic acid, and tripalmitin100 mg/kg q 6 h prn up to 4 doses[2]”;
poractant alfa, a “modified
porcine-derived minced lung extract containing phospholipids, neutral lipids,
fatty acids, and surfactant-associated proteins B and C 200 mg/kg followed by
up to 2 doses of 100 mg/kg 12 h apart prn[2]”; and calfactant, a
“calf lung extract containing phospholipids, neutral lipids, fatty acids, and
surfactant-associated proteins B and C 105 mg/kg q 12 h up to 3 doses prn [2].”
Following the therapy, lung compliance can improve very fast.
Possible complication
With the use of the drug, the
infant is put into a risk of bleeding into the lungs. Surfactant treatment can
result to this kind of bleeding and approximately 10% of very small infants are
affected. Infants receiving surfactant for respiratory distress syndrome have a
higher possibility of apnea of prematurity. It is important to note that this
form of therapy should only be used where there are facilities for ventilation [2].
Continuous positive airway pressure (CPAP)
This is a common gentler means of
aiding breathing in infants with respiratory distress syndrome. Through the use
of this technique, oxygen mixture is delivered to the lungs through nasal
prongs or the use of a tube that is placed through the nose instead of an
endotracheal tube. Continuous positive airway pressure may be used before
resulting to high-frequency ventilation or for infants who have been on a
ventilator and have started to improve [7].
High-frequency ventilation
High-frequency ventilation is a new
technique used in the management of respiratory distress syndrome [3].
Infants suffering from severe respiratory distress syndrome are normally
treated with the use of a ventilator. High-frequency ventilation uses a machine
(the ventilator) that takes over the working of the lungs. This machine
delivers air to the lungs under pressure. For very small infants who are not
able to breathe on their own after birth, tracheal tube ventilation is used as
an emergency procedure. High-frequency unlike the conventional ventilation uses
various commercially available tools for providing gas exchange at low tidal
volume rates [1].
Possible complications
Infants who have been treated with
the use of high-frequency ventilation at times develop secondary complications.
The cause of these complications has been attributed to high respirator
pressure as well as high concentration of oxygen [3]. Due to the
possibility of secondary damage to the lungs, high-frequency ventilation should
be closely monitored.
Extracorporeal membrane oxygenation (ECMO)
This is a possible treatment for
respiratory distress syndrome. It is the provision of oxygen into the lungs of
the infant through a device that emulates the process of gas exchange of the
lungs. Nevertheless, infants who are less than 4.5 pounds (2 kilograms) cannot
be put on extracorporeal membrane oxygenation. This is due to their excessively
small vessels for cannulation. The size of their vessels can prevent sufficient
flow due to the restrictions from cannula size as well as successive higher
opposition to flow of the blood. Additionally in newborns who are aged below 34
weeks there is poor development of various physiologic systems, particularly
the cerebral vasculature as well as germinal matrix. This can result in high
sensitivity top small changes in PaO2, pH, and intracranial pressure.
Consequently, newborns are at excessively high danger for intraventricular
hemorrhage (IVH) if put on extracorporeal membrane oxygenation if they are less
than 32 weeks gestational age [4]. Additionally, because of the
increased risk of intraventricular hemorrhage, it has become necessary that an
ultrasound the brain is taken before putting an infant on extracorporeal
membrane oxygenation. This means that the device has failed to be used for
majority of infants suffering from respiratory distress syndrome.
BIBLIOGRAPHY
- Wiswell, Thomas E. et al. High-Frequency Jet Ventilation in the Early Management of Respiratory Distress Syndrome Is Associated With a Greater Risk for Adverse Outcomes, Pediatrics 1996; 98; 1035.
- Frantz, Ivan. D., Joseph Werthammer, and Ann. R. Stark. High-frequency ventilation in premature infants with lung disease: adequate gas exchange at low tracheal pressure, Pediatrics, 1983 71(4).
- Rodriguez RJ, Martin RJ, and Fanaroff, AA. Respiratory distress syndrome and its management. In Fanaroff and Martin (eds.) Neonatal-perinatal medicine: Diseases of the fetus and infant; 7th ed. (2002):1001-1011. St. Louis: Mosby.
- Schwartz, R.M., Luby, A.M., Scanlon, J.W., & Kellogg, R.J. Effect of surfactant on morbidity, mortality, and resource use in newborn infants weighing 500 to 1500 g. New England Journal of Medicine, 330 (1994): 1476-1480.
- Hermansen Christian L., and Kevin N. Lorah, Respiratory Distress in the Newborn, Am Fam Physician. 2007: 76(7):987-994.
- Pokora, Thomas, Dennis Bing, Mark Mammel and Stephen Boros, Neonatal High-Frequency Jet Ventilation, Pediatrics 1983; 72; 27
- Louis, J. M., et al. “Perinatal intervention and neonatal outcomes near the limit of viability.” American Journal of Obstetrics and Gynecology 191, no. 4 (2004): 1398–402.
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