Neonatal Respiratory Distress Syndrome
Morgan Abbott
Central Piedmont Community College
Author Note
Morgan E. Abbott, Respiratory Therapy Program, Central Piedmont Community College
Contact: msmit165@cpcc.edu
Neonatal Respiratory Distress Syndrome
Neonatal Respiratory Distress Syndrome (RDS) is a condition that is seen in premature babies that makes it hard for them to breathe. It is one of the most common reasons that babies are admitted into the neonatal intensive care unit (NICU). Babies that are premature are more susceptible to neonatal RDS but there are preventable measures that can be taken to lower the chances. When a baby is born with RDS there are many symptoms that are seen as well as tests that can be ran to ensure that RDS is the actual prognosis. The treatment process needs to begin imminently after birth as well as monitoring the baby carefully for any side effects. Neonatal respiratory distress syndrome is a problem seen every day but with the knowledge of prevention, causes, and treatment handling RDS can be a little less difficult.
Having a healthy pregnancy and taking all the right steps to prevent going into premature labor is one of the best things to do in order to prevent neonatal respiratory distress syndrome. Good prenatal care from the very beginning of a pregnancy is the key to having a full term pregnancy. This is important because having improper timing of a delivery increases the risk of RDS. Good prenatal care includes regularly scheduled checkups, prenatal vitamins, a healthy diet, exercise and many other small but important things. Sadly, there are times where premature labor just happens even with perfect prenatal care.
Before delivery, a test, called an Amniocentesis, can be run to check the readiness of the baby’s lungs. These tests are done to check how stable the lungs on and if they are strong enough to work alone after birth. The results of this test also determine if the mother may have a full term vaginal delivery or not. It is possible that a cesarean birth or induced delivery may be necessary but having a full term birth is the ultimate goal. Cesarean or induced births shouldn’t happen until the tests show that the baby’s lungs are fully developed or until the mother is at least 39 weeks pregnant unless, there is a medical problem that is causing otherwise. Corticosteroids are given to help speed up the baby’s lung development before delivery. When preterm labor is expected to happen within a week the doctor will order these medications to help not only the baby but also the mother. The British Association of Perinatal Medicine, and the U.S. National Institutes of Health recommends: “Antenatal treatment with corticosteroids should be considered for all women at risk of preterm labor between 24 and 36 weeks. Treatment should consist of two doses of betamethasone given intramuscularly 24 hours apart or for doses of dexamethasone given 12 hours apart.” In an observational study betamethasone was shown to be safer than dexamethasone because of its lower risk for periventricular leukomalacia. Although, these medications cannot fully prevent RDS but the treatment will reduce the severity.
Prevention is possible but is not always the case. The main cause of neonatal RDS results from underdeveloped lungs and insufficient protein from surfactant. According to “Neonatal and Pediatric Respiratory Care”, surfactant is a substance that is naturally produced inside the lungs that helps keep air in the lungs. SP-B is the protein in surfactant that enhances stability and spreading of lipids it is a hydrophobic protein. RDS affects the production of surfactant by having an SP-B deficiency. A fully developed pair of lungs in most cases would have surfactant present. Lack of surfactant is a cause of RDS but there are a lot of other causes as well.
Genetics and family history play a role in neonatal RDS. If a mother has given birth to a child with RDS then risk of subsequent birth of children with RDS would increase. Diabetes in the mother has shown to raise the chances of RDS in a pregnancy. Also having a multiple pregnancy such as twins or triplets, the chances for RDS increase.
RDS is uncommon in babies that are born full-term and is mostly seen in babies delivered before 37 weeks. The earlier the baby comes before full term the higher the chances are of having RDS. Cesarean delivery, rapid, or an inducted labor will increase the baby’s chances of having RDS. The stress that comes along with cesarean, induced, or rapid labor plays a part in the breathing pattern once the baby is introduced into the world. When a mother has problems during delivery there is a possibility of less blood flow to the baby and RDS is more likely than not. The heart and lungs work together. When the heart isn’t pumping enough blood, due to less blood flow, the lungs aren’t able to perform at the best capability.
When a baby is born with RDS, normally the symptoms appear within minutes of birth or within 6 hours after birth. However, that is not always the case and it could take up to several hours for symptoms to show up. Most infants look distressed and can have a see-saw appearance during retractions, when the abdomen protrudes as the chest pulls it in. (Walsh 2015) Infants that are very preterm can show signs of hypotonic and unresponsiveness. Walsh explains in Neonatal and Pediatric Respiratory Care, “Intercostal and subcostal retractions are apparent and occur when the negative intrathoracic inspiratory pressures distort the chest wall instead of inflating the stiff lungs.” What this means is that healthy lungs would not have retractions and the lungs would inflate and cause equal symmetrical chest rise while lungs with RDS have pressures that cause retractions and make expansion of the lungs harder.
The most common symptoms of RDS are: cyanosis, apnea, and respiratory failure. Cyanosis is when the color of one’s skin has a bluish color to it due to the lack of oxygen and apnea is when breathing completely stops. Respiratory failure is a term that categorizes a lot of things together. Signs of respiratory failure could be nasal flaring, rapid or shallow breathing, and shortness of breath or grunting sounds. When a baby is born a test called an APGAR is performed 1 minute after birth and again 5 minutes after. It is an acronym for what it checks for which is Appearance, Pulse, Grimace, Activity, and Respiration. This is just one way to note the pulmonary stability of a newborn.
Treatment for RDS should start at birth. There are a few important things that need to be managed in infants with RDS; “Preventing hypoxemia and acidosis, optimizing fluid management, reducing metabolic demands, preventing worsening atelectasis and pulmonary edema, minimizing oxidant lung injury, minimizing lung injury caused by mechanical ventilation.”(Wilkins2012) Preventing hypoxemia and acidosis will optimize surfactant production as well as prevent right to left shunting and optimizing fluid management will avoid hypovolemia, shock, and pulmonary edema. (Wilkins2012) Managing those key things will help the treatment process go a lot more smoothly. Surfactant replacement, oxygen therapy, and continuous positive airway pressure (CPAP) are all ways to treat RDS.
Exogenous surfactant administration is one of the more common ways of treatment for premature babies with RDS. (Walsh2015) There are several different types of surfactant that is used to treat babies with RDS. Exogenous lung surfactant is either synthetic or natural. Both options work in reducing the severity of RDS but in clinical trials natural surfactant is shown to be the more suitable choice. Surfactant is given at the time of birth or soon after to infants who are seen as highly capable of developing RDS. Surfactant is delivered through an endotracheal tube into the infant’s lungs for a few seconds. This can be done manually or by intermittent positive-pressure ventilation. Five other methods of delivering surfactant have been tried but all vary in their success rate; including antenatal intra-amniotic instillation, pharyngeal instillation, laryngeal mask instillation, direct tracheal instillation without intubation, and surfactant nebulization. (Walsh 2015)
Oxygen therapy is needed to help maintain the partial arterial oxygen pressure between 50 and 80 mmHg, partial arterial carbon dioxide pressure between 40 and 80 mmHg, and pH at least 7.25. (Walsh2015) Delivering oxygen to a neonate with RDS is done so with an oxygen hood. The oxygen hood warms and humidifies the oxygen that is getting delivered to the infant. Oxygen hoods also have an oxygen blender that allows complete control over the oxygen concentration that is being delivered. If oxygen therapy is not sufficient enough to keep oxygen saturation higher than 85% at an FiO2 of 40% to 70% or greater than CPAP may be initiated. (Walsh2015) CPAP can be used with nasal prongs or with a nasopharyngeal tube while using a continuous-flow ventilator. Starting CPAP early in a premature newborn could reduce the need for intubation. The usual starting point for CPAP in RDS infants is 4 to 6 cm H2O. Adjusting the pressure is crucial for these infants. In order to safely adjust you would need to do so in increments of 1 to 2 cm H2O to a maximum of 8cm H2O. (Walsh2015) It is also important to continuously monitor the infant’s respiratory rate, effort, and their oxygen saturation.
Having knowledge and an understanding about the preventative measures, causes, and treatments for RDS will help you have the better outlook and outcome throughout pregnancy and birth. Although preventing RDS from happening is ideal, sadly, in a lot of cases RDS still occurs. Early recognition and treatment of this common syndrome may not be able to fully prevent it but will decrease complications as well as mortality risks of these infants.
References
Bahakta KY. Respiratory Distress syndrome: In Cloherty JP, Eichenwald EC, Hansen AR, Stark AR, editors: Manual of neonatal care, ed 7, Philadelphiaa, 2012, Lippincorr Williams and Wilkins.
Liszewski, M. C., Stanescu, A. L., Phillips, G. S., & Lee, E. Y. (2017). Respiratory distress in neonates: Underlying causes and current imaging assessment.Radiologic Clinics of North America, 55(4), 629-644.
Reuter, S., Moser, C., & Baack, M. (2014). Respiratory Distress in the Newborn. Pediatrics in Review, 35(10), 417–429.
Walsh, B. K., BS,MBA,RRT-NPS, RPFT, ACCS, FAARC. (2015). Neonatal and Pediatric Respiratory Care (4th ed.). St. Louis , MI: Saunders.