Tuesday, February 5, 2013

Infant Respiratory Distress Syndrome



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
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