Respiratory Distress Syndrome

Respiratory Distress Syndrome -Introduction: Generally speaking, there s an overlap between the presentations of cardiac and respiratory illnesses in neonates. Also there s a considerable overlap between the respiratory illnesses themselves in neonates. Thus, it s important to understand how to approach such patients in order to narrow the differential diagnosis list and identify the presenting illness, so that to manage it correctly. If the correct diagnosis of the presenting illness was missed, there might be a chance that the used measures in management will worsen the patient s condition. For example, cyanosis as a symptom might of respiratory or cardiac in origin. In cyanosis of respiratory origin, O2 supplement is an integral part in its management and O2 saturation should be maintained near its normal level as much as possible. But in cases of transposition of the great vessels; cyanosis of cardiac origin, O2 saturation should be maintained around 65-75% in order not result in pulmonary hypertension. The causes of respiratory distress/ illnesses in neonates can be divided into pulmonary extrapulmonary causes. *Extrapulmonary causes: Cardiovascular (Congenital heart diseases, hypovolemia), Hematologic (Polycythemia, anemia), Metabolic Disturbances (Acidosis, hypoglycemia), Others (Hypothermia, CNS hemorrhage, drug use, macroglossia. In macroglossia,a feature of hypothyroidism, the tongue will flip back obstructing the airway. It can be managed initially with placing the neonate in a prone position or placing a mouth piece to prevent the tongue from flipping back. *Pulmonary causes: 1-Upper airway obstruction, like in choanal atresia. Choanal atresia is a congenital disorder where the back of the nasal passage (choana) is blocked, usually by abnormal bony or soft tissue (membranous) due to failed recanalization of the nasal fossae during fetal development. (Wikipedia). When the patient is calm, he/she ll be cyanosed. But the patient s color will turn into pink (normal) when he/she cries (due to the opening of the mouth). This is the classical presentation of choanal atresia. The diagnosis is confirmed using a CT scan. It s managed initially by placement of a mouth piece to sustain their breath, then it s corrected surgically. 2-Larnygomalacia: weakened muscles of the larynx resulting in collapse of the airway during expiration.* It s managed by cauterization and it ll resolve around the age of 2 yrs. (the dr didn t specify which part of the larynx exactly, and different treatment measures are written in Wikipedia.) * The mechanism of the obstruction in laryngomalacia is described as the following in Wikipedia: soft, immature cartilage of the upper larynx collapses inward during inhalation, causing airway and

obstruction. in older patients, especially those with neuromuscular conditions resulting in weakness of the muscles of the throat. 3-Tracheomalacia: is a condition characterized by flaccidity of the tracheal support cartilage which leads to tracheal collapse especially when increased airflow is demanded. (from Wikipedia. It was mentioned by the dr without explaining it.) 4-Vascular ring: is a very rare condition that presents with stridor or wheezes in addition to some gastrointestinal symptoms. Proper investigation begins with the use of barium study, in which an indentation of the esophagus is seen as a result of the blood vessel encircling it (bearing in mind that the trachea is encircled too).confirmed the diagnosis is done using an MRI. It s managed by surgical correction. Other pulmonary causes that should be kept in mind in suspected cases: respiratory distress syndrome (RDS), transient tachypna of the newborn (TTN), pulmonary hypoplasia,, meconium aspiration, congenital pneumonia, diaphragmatic hernia, persistent pulmonary hypertension of the newborn, RDS Previously called hyaline membrane disease. It s difficult to differentiate RDS from congenital pneumonia and TTN on clinical presentation. Although some full term infants are at risk for developing RDS (infants of diabetic mothers, c/s deliveries, white race), It s a disease of prematurity. -Approaching the Patient: A full history should be taken, a thorough physical examination should be conducted, CBC and other relevant lab investigations and imaging studies must be done to rule out extrapulmonary causes of the presenting signs and symptoms. (Like: hypoglycemia, polycythemia, hypotensive, acidosis). Each condition has its own clues. *History: the relevant details of history history: in such conditions are mainly found in the perinatal -Prenatal: maternal age (advanced maternal age increase the risk of trisomy 21 and other genetic syndromes.), history of gestational diabetes (would direct our thinking to TTN, RDS, hypoglycemia, transposition of the great vessels), HTN (leads to IUGR, polycythemia, hypoglycemia), drug intake (Lithium intake leads to Ebstein's anomaly*. Adminstration of sedatives to the mother would result in either fetal respiratory depression or apnea), PROM suggests neonatal sepsis. -Natal: prematurity is a known risk factor for RDS. Post-term delivery or presence of meconium when the membrane is ruptured increase the risk for meconium aspiration syndrome. Mode of delivery (C/S suggests TTN). Oligohydramnios is a major cause of pulmonary hypoplasia.

*Physical examination: the type of the associated respiratory distress signs should be exactly mentioned in addition to the presence of chest deformities. *Investigations and Imaging Studies: chest X-ray must be obtained to aid in differentiating between the suspected pulmonary causes.(it s considered as a part of the chest physical examination until 2 yrs of age.) -Disease Course: The newborn looks normal after delivery, then signs and symptoms of respiratory distress start to develop after 30 minutes of delivery. The signs and symptoms reach their peak after 2 hours, then the chance for the patient to die is highest after 24-48 hours of delivery. If the neonate survived the aforementioned course, after 72 hrs, some RDS patients will start to produce endogenous surfactant and consequently, the clinical picture will improve. RDS was a major cause of death in neonates. Nowadays, the availability of surfactant improved the outcome of RDS significantly. -Ruling Out Other Possible Causes: Congenital pneumonia is difficult to differentiate from st RDS, especially during the 1 48 hours of the disease course because the chest X-ray appears normal. After 24 hours of congenital pneumonia course, the classical consolidations of pneumonia can be seen on a chest X-ray. As a precautional measure, empirical antibiotic treatment should be started in such instances until the exact cause of the signs and symptoms is identified. (Group B Streptococci is a frequent cause of congenital pneumonia) This part was done by Mohammad Nayef :D True wisdom comes to each of us when we realize how little we understand about life, ourselves and the world around us. Socrates. Dedication takes a lifetime, but dreams last for a night!

after 72 hours, patients start producing their own surfactant, and recovery will happen. Recovery is prolonged by baro-trauma or oxidative injury. So it's important to manage the amount of oxygen and the ventilator set up used which makes a difference in their survival, complications and length of hospitalization. Always remember that the number one risk factor for RDS is prematurity, although it can happen is other cases, but it's early onset after birth. From Nelson Essentials: Surfactant is produced in 32-34th weeks of gestations, and by the 36th, sufficient surface-active material is produced by the type II cells in the lung, is secreted into the alveolar lumen, and is excreted into the amniotic fluid. The concentration of lecithin in amniotic fluid indicates fetal pulmonary maturity. The ratio of lecithin(changes) to sphingomyelin(constant) L/S is determined. An L/S ratio of 2:1 indicated pulmonary maturity. The presence of minor phospholipids, such as phosphatidylgylcerol, also is indicative of fetal lung maturity and may be useful when L/S ratio is borderline or possibly affected by maternal diabetes. The absence of phosphatidylgylcerol suggests that surfactant might not be mature. Physical Examination should be: 1- brief but thorough 2- checking for signs of respiratory distress: Tachypnea, as the normal respiratory rate for full terms is up to 60, so if you are having more than 60, then he/she is tachypnic. Grunting Nasal Flaring Retractions Cyanosis 3- Temperature, blood pressure, and skin perfusion.

This is a typical/classical RDS X ray; we can see tracheal tube inside the trachea, ground glass appearance ورقة راشش عليها ملح و فلفل),(زي and air bronchogram because there are altelectatic changes in the alveoli, some are open and others closed so this is how it appears (radiolucent shadows). Always remember that RDS is none homogenous disease, due to partial alveolar pressure which is different from one area to another. Surfactant works to homogenize the pressure, and this reduces the chances to develop pneumothorax from mechanical ventilations, which RDS can complicate into.

Here you can see white out lung, which means that the lung and liver have similar color. White out means we have sever RDS; the lung is very stiff, barely any air in the lungs. (Nilson adds: even obliterating the distinction between the atelectatic lungs and the heart) What might decrease the risk of RDS: pregnancies with chronic or pregnancy-associated hypertension prolonged rupture of membranes antenatal corticosteroid prophylaxis (Major factor is changing the survival in many patients, and given 2 doses after the age of 24 weeks of gestations, 12 hours apart.) All of this is due to steroid release. If the patient was stressed in uterus, this will lead to excessive steroids production, which will promote the surfactant release. Surfactant is needed most for reducing the surface tension (among other jobs but this is the most important). In utero, the alveoli are filled with fluids and once you are born, you need higher pressure to open the alveoli.

Example to understand the idea: A brand new balloon if given to a child to inflate won't do it, but you as an adult can, and if you inflate it, and deflate it and then given it to the child he will be able to inflate it (The hardest is the first time). Now let's take that balloon and fill it with water and then release the water out. The balloon will collapse and even more pressure is needed to open it. This is how the lungs of a newborn are, once the fluid is out, you need higher pressure to open up the alveoli. Surfactant decreases the surface tension, and that aids in breathing and decreases the work needed to open up and start the gas exchange. From Nilson Essentials: Strategies to prevent preterm birth: 1- Maternal cervical cerclage (Treatment for cervical incompetence is a surgical procedure called cervical cerclage, in which the cervix is sewn closed during pregnancy.) 2- Treatment of infections 3- Bed rest 4- Administration of tocolytic medications (anti-contraction medications or labor repressants, like Terbutaline, Indomethacin, Nifedipine, Magnesium sulfate.) Surfactant is made and stored by type 2 pneumocytes. When we want to deliver surfactant, we given exogenously through the endotracheal tube when the patient needs it. The doctor said he won't discuss or talk about the rescue or prophylaxis as they are advanced to our stage. From Nilson Essentials: (Just if you got a question or anything to be in the safe side) If premature delivery is unavoidable, the mother is given betamethasone and thus to the fetus to stimulate fetal lung production of surfactant and this requires multiple doses for at least 24 hours. Complications include: Patent Ductus Arteriosus, Pulmonary Air Leaks, Brunchopulmonary Dysplasia(Chronic Lung Disease), and Retinopathies. The second problem is: Transient Tachypnea of the Newborn: It's a mild and self-limiting disease, due to increased respiratory rate (tachypnea is in the name of the disease after all), no retractions, and there is mild cyanosis. FiO 2 is lower than 0.4, and the baby is usually term infants but product of C/S. Normally when a mother goes into labor,

because of uterine contractions, there will be catecholamine release and this will help the resorption of the fluid in the lung, aided by squeezing through the birth canal. Going through C/S will put the baby at risk of having that fluid in the lung and develop transient tachypnea of the newborn. The problem is there is fluids present in the lungs, maternal IV fluids associated. CXR with prominent vascular markings. This X-ray is classical for Transient Tachypnea of the Newborn. From Nilson Essentials: CXR Shows prominent central vascular markings, fluid in lung fissures, overaeration, and occasionally a small pleuaral effusion. You need to rule out pneumonia. We used to put patients on oxygen and antibiotics immediately, but now we wait for about 6 hours, some wait for 24 hours, and if the patient is not responding we start them on antibiotics. But here in the hospital because of the crowdedness, we start at 6 hours. So if the demand on oxygen increased, or oxygen is needed beyond 6 hours, or he/she is not responding, you need to think of another cause. Another disease that might present with cyanosis and respiratory distress:

Neonatal Meconium Aspiration Syndrome: We can't prevent all MAS, because the mother might have meconium in the liquor, and when the membrane ruptures, we do suction for perineum, and if the baby didn't breath we do suction through an endotracheal tube. Why does this happen in utero? If the baby has fetal distress or hypoxia, the patient due to hypoxia will have relaxation of the anal sphincter, and the will lead to the passage of the meconium into the amniotic fluid. When the blood supply gets better, gasping happens, and then he/she aspirates the meconium. On Chest X-Ray (CXR): Increased density, irregular infiltrates Areas of hyperexpansion, areas of collapse(due to ball valve mechanism) Fluffy non-homogeneous infiltrates May be hard to distinguish from retained fluid, pneumonia

**Notice in the CXR that the particles are bigger than those in RDS. One of the complications of call valve mechanism is that air will keep going into the alveoli and tension increases leading to rupture and pneumothorax, making those patients difficult to ventilate, as they might have PPH (Persistent Pulmonary Hypertension), with right to left shunting caused by increased pulmonary vascular resistance. Comorbid diseases include those associated with in utero asphyxia that initiated the passage of meconium. From Nilson Essentials: Treatment: general supportive care and assisted ventilation. Infants with PPHN should be treated for PPHN. If sever hypoxia doesn't subside with conventional or high frequency ventilation, surfactant therapy, and inhaled nitric oxide, Extracorporeal membrane oxygenation (ECMO) may be beneficial.

This part was done by your colleague Ahmad Abbadi.. In memory of Claymore.. My favorite manga and book I have ever read. "My existence was nothing more to her than a stone by the side of the road. I wasn't enough to fill her belly. Or perhaps I didn't even get reflected in her eyes. I couldn't even hate the beast that killed Teresa. It was me, overcome by fear, that I could not forgive." -Clare, Claymore, Scene 24: Marked for Death, Part 7. "Being thrown away by humans, devoted to them even though you aren't one of them... and once they are finished with you, they have you end your life yourself... and not even an ounce of gratitude for all that. On the contrary: for your whole life you are hated and reviled. It really is idiotic. We are a different species after all. Once you start seeing things that way, it all becomes very easy to accept. Do humans shed tears for the birds, pigs, cows and sheep that become their food? Of course they don't. They are a different species after all. That is nature. That is the truth. That is Providence. Your way of thinking up to now was the warped one." -Riful of the West, Claymore, Scene 43: The Witch's Maw, Part 3. To all our friends, thank you for every precious memory.. The best is yet to come :) And Happy Birthday Mohammad Nayef :P Now you can't say that I didn't make it a special Bday Your colleagues: Ahmad Abbadi, Mohammad Nayef.