Click here to view next page of this article

 

Respiratory Problems of the Newborn

Hyalin membrane disease, respiratory distress syndrome is the big one that you worry about in preterm babies respiratory disorders of the newborn. The cause is inadequate pulmonary surfactant. You get atelectasis of the alveoli, edema and cell injury. Proteins leak into the alveoli and inhibits the surfactant function. So even if there is adequate surfactant they still cannot function well. Antenatal steroids and prevention of prematurity are the only two things we know that will prevent it.

Clinical signs; and these are classic. High respiratory rate, normally 60, 40-60. A premature is usually around 60 but they are breathing 90-120 times a minute, they are just huffing and puffing. Retractions you see in between their ribs, above their sternum, underneath their ribs, their nose flares, they are grunting in the attempt to keep their alveoli open and they are blue.

Okay, long term sequelae; bronchopulmonary dysplasia in up to 30% of the survivors, retinopathy prematurity because the retinal vessels are susceptible to hyperoxia, but again how much of this is the RDS and how much is the prematurity is hard to separate out. Neurologic impairments. The sicker the infant the more likely these complications will happen.

Okay, we are going to do a little case study. Iím not going to have you call out answers, I just want you to think about this as this goes along because this is the sort of thing you may see on the Boards, differentiating causes of respiratory distress depending on how it presents and when it presents. So, you are called to the newborn nursery to look at a three-hour-old infant male who is grunting and cyanotic. The nurses has already place an Oxy-hood, and what do you do next? Well, you want to know about the history as you examine the baby or ask the nurse whatís going on.

So what are the things you would think of? The common pulmonary cause is transient tachypnea because of retained fetal lung fluid, and you get kind of a starburst pattern. Thatís the classic association with TTN or retained fetal lung fluid - itís called different things - but that starburst pattern out from the hyalin and they usually tend to be pretty good volume lungs. And by good volume I mean more than eight ribs on an inspiration film. Hyalin membrane disease, even though itís a term baby. You know, we can still have hyalin. Thereís a percentage of term babies who do have that. Maybe the mom has an undiagnosed gestational diabetes. We donít know how many visits she had or whether she had a glucose tolerance test. Meconium aspiration.

Persistent pulmonary hypertension from a bunch of different things. Meconium aspiration will do that, pneumonia will do that, idiopathic, you know some maternal stress and they re-monitor vasculature and it doesnít Ö the resistance doesnít drop with that first big deep breath that they take. Some of the uncommon causes would be airway obstructions, and so is space-occupying lesion, pulmonary hypoplasia, chylothorax - Iím going to go through these quickly because they are in your handout - diaphragmatic hernia. Thereís more than once that weíve not diagnosed these pre-natally and you get your first x-ray and hereís gut up in the chest, not in the abdomen. Thatís a real big reason to be blue.

Non-pulmonary causes; always cardiac. You have the hyperoxia test. You get a blood gas in room air, get a blood gas in 100% oxygen, and if it doesnít raise much then chances are good that you have a cyanotic congenital heart disease. Diabetic cardiomyopathy means that you have a big old dilated heart that just isnít functioning very well. Metabolic or are they acidotic for some reason? Or are they hypoglycemic, hypothermic, those things can typically cause respiratory distress so always making sure about the basics. You know, are they warm, are they well perfused, and is their glucose adequate?

Then you look at the other organ systems. A bleed in the brain, edema, motherís drugs that she got during labor, those can cause respiratory distress. Hemorrhage, hypervolemia, or polycythemia can cause respiratory distress. Labs that you would get on any of these babies usually is ABG, as I said, room air and 100%, the hyperoxia test to look for congenital heart disease, cyanotic congenital heart disease, CBC with differential and platelets, cultures, chest x-ray. Youíll already have done a screening glucose, you may need to do a serum.

The most likely diagnosis in this case, though, based on being a term baby, no history of maternal problems, would be sepsis, number one. But congenital heart disease until we know the results of those tests, we donít know, or just transient tachypnea. Prolonged transition. So watching these babies; you get the initial test, get them oxygenated, and then watch what happens with them. So early onset risk factors arenít real telling.

Now this is a little later, still considered a newborn, still in my realm. You are making rounds in the hospital and you are the pediatrician on call for the day and they page you to the ER because the mom has brought in her baby, six-day-old girl whoís not feeding well and sheís breathing hard. So the differential may include a lot of the same things, but the likelihood of what it is is going to be a little bit different. History and physical; you still want to know the same. You want the past history, and thatís the nine months she was carried plus the six days sheís been alive.

Again, evaluation is directed by the history and physical. A vigorous but pale tachycardic baby, for sure you want to get a hematocrit and platelets on, but you might not rush to do an echocardiogram. That sort of thing. But again, the CBC, platelets, chest x-ray. You may need an echo, you may need an abdominal ultrasound if you are worried about there being a splenic rupture or a subcapsular hematoma on the liver from birth injury.

Management is just the usual, the ABCís. Theyíve got to have a good airway, theyíve got to be breathing and theyíve got to be circulating well. So oxygen, volume replacement. Thatís whatís necessary. Antibiotics, prostaglandins if you think itís a ductal-dependent lesion and their duct is closed. So thatís something that might be considered.