Neonatology (Newborn Medicine): Introduction

00:01 In this lecture, we’re going to discuss delivery of the newborn, how newborns are resuscitated and TTN or transient tachypnea of the newborn.

00:11 Let’s go over the epidemiology of newborns in the U.S.

00:15 There are 4 million births per year.

00:18 Ten percent of infants who are born require some sort of intervention at birth to keep them going and 1% require frank resuscitation.

00:28 So we’re doing a lot of infant resuscitation in U.S.

00:33 Let’s keep in mind the fetal circulation.

00:36 Here, you can see a picture of it here and I won’t go through it in detail, but what’s key is remembering that these children at their very first breath are dramatically altering the way blood flows through their heart.

00:49 They’re closing off their patent ductus arteriosus and they’re reversing flow so that they can now suddenly adopt the adult circulation.

00:58 This is one of the most miraculous engineering feats in the history of the world.

01:03 So we need to guide them through this transition, so that they’ll maintain a healthy state as blood flow is dramatically reversed through closing of the patent foramen ovale and closing of the ductus arteriosus.

01:20 So let’s go through that physiology.

01:22 The patient has their first breath.

01:25 This causes a rapid expansion of the lungs.

01:28 Now, molecular pumps turn on and rapidly pull fluid out of the airspace through osmosis and into the interstitium of the lungs.

01:39 Remember, while in utero, their lungs were filled with fluid.

01:43 In fact, they even manufactured a tiny percentage of that amniotic fluid.

01:48 Now, suddenly, they must be emptied.

01:51 Oxygen causes a rapid dilatation of the pulmonary arteries, thus decreasing pulmonary vascular resistance.

01:59 This leads to the sympathetic nervous system which thus increases systemic vascular resistance through stress.

02:08 And that discrepancy, the differences in vascular resistance result in the transformation from a fetal to an adult circulation pattern.

02:18 The patent ductus arteriosus closes, the patent foramen ovale closes and those close over the first 1-2 days, which sort of seal in this new permanent architecture.

02:30 So occasionally kids will need resuscitation at birth.

02:35 There are many potential risk factors for needing resuscitation.

02:39 Patients who are twins, triplets or otherwise have multiple gestations are at increase risk for needing resuscitation.

02:47 If a mother has an infection around the time of delivery, that certainly can increase the risk.

02:53 If the mother received magnesium for a preterm labor, that baby will have a decreased motor tone and thus will need likely a resuscitation.

03:04 Maternal substance abuse increases risk and need for resuscitation.

03:09 There can also be some problems with labor that can increase the risk and need for resuscitation.

03:15 Breech presentation, a failure to progress may result in distress in the infant.

03:21 Infants with nuchal cords may have decreased vascular perfusion prior to delivery and may need resuscitation.

03:28 Infants who are stressed will often have meconium in the amniotic fluid prior to being delivered.

03:35 Those infants are then at increased need for resuscitation, not only because they were stressed and thus produce meconium but also because meconium can get into the lungs and cause pneumonitis.

03:47 Likewise in mothers who had chorioamnionitis at the time of delivery, those infants may be in distress and certainly if there was placental abruption or placenta previa or some other problem like that, these infants would be at increased risk for needing resuscitation.

04:04 In cases where some previous risk factor for needing resuscitation occurs, the obstetrician may decide to have the pediatrician come down to the delivery room to assist with the resuscitation, just in case.

04:20 When the pediatrician arrives, they have to obtain information about the prenatal history and delivery so they know what’s going on.

04:28 The pediatrician should assess the room and make sure it’s ready to go, make sure the warmer is active and plugged in.

04:35 Make sure there are clean, dry cloths available for drying out the baby and make sure there is suction available and airway equipment in the unfortunate need for true resuscitation or intubation.

04:48 Pediatrician should know the gestational age and the estimated weight in advance.

04:53 This is because any difference there may be of clues as to what’s going on.

04:58 In general, as that baby is first being handed to the pediatrician, the pediatrician is asking themselves three critical questions.

05:08 These are really important.

05:10 One, is the infant full-term? A premature baby is going to be managed differently.

05:15 Two, does the infant, when they’re handed to the pediatrician, have good tone? Is the infant floppy or they’re all balled up? All balled up is good.

05:26 And is the infant already crying? If an infant is handed off to the pediatrician as full-term with good tone and if that infant is crying by the time they make it across the room to the pediatrician, there is very low likelihood of needing to do resuscitation.

05:44 The pediatrician’s role can be to dry off the infant, to do some basic tasks such as vitamin K inoculation, swaddle the baby and hand that baby right off to the mother.

05:55 If on the other hand, one of these questions is true, the infant is not full-term, the infant has poor tone or the infant is not crying or breathing, we can expect the resuscitation.

06:08 There are several important diagnostic procedures that are necessary for infants where we have suspected HIE.

06:16 It is important to examine the placenta and look for clots and other findings which might be consistent with intrauterine stress for the infant.

06:25 We need to get a cord blood gas as well.

06:27 The cord blood gas can be very helpful in understanding the acid base status of the infant.

06:32 From the infant themselves it's important to get a CBC with differential and arterial blood gas, a comprehensive metabolic panel, as well as a PT/PTT and a D-dimer to look for disseminated intravascular coagulation.

06:46 We will routinely get an EEG on these newborns after they're born to assess brainwaves as a way of looking at cognitive damage.

06:53 And also, we will do a brain MRI usually at around 4 to 7 days.

06:59 We don't do an ultrasound because that is really for Perry Ventricular, Lucan, Malaysia, or other causes of intraventricular Bleed.

07:07 The brain MRI is more helpful at distinguishing somewhere things such as white matter and gray matter differentiation.

07:15 We'll do an LP if there's a concern for meningitis and we'll also do metabolic labs.

07:20 If we're concerned about metabolic disease for the treatment of HIE, we will engage in a relatively new therapy which wasn't done 10, 15 years ago, but has been shown to be very effective, which is called therapeutic hypothermia.

07:35 What we'll do is relatively quickly after birth, usually within 6 hours of birth, and for another 72 hours we will lower the temperature of the baby to 33.5 degrees Celsius.

07:48 While doing this, we of course maintain oxygen and ventilation.

07:52 We will avoid fluid overload because we don't want to cause brain edema, which can happen with fluid overload in these infants.

07:59 And we will control any seizures, if present, with medications.

08:03 By lowering the temperature of the baby, this has been shown to improve outcomes in infants with moderate to severe hypoxic ischemic and self allopathy and the number needed to treat which is a really important measure of how effective something is, is quite low.

08:19 You only have to do this for 6 babies before you prevented death from HIE.

08:24 It also increases the likelihood of normal neurologic outcome at 18 months, and overall it increases that rate a substantial amount from 24% to 40%.