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Persistent Pulmonary Hypertension in the Newborn. A Star Fleet Academy Short Course. Pulmonary Hypertension. Examples: NSAIDS during pregnancy Persistent fetal circulation Total anomalous pulmonary veins Mitral valve stenosis / diabetic cardiomyopathy
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Persistent Pulmonary Hypertension in the Newborn A Star Fleet Academy Short Course
Pulmonary Hypertension • Examples: • NSAIDS during pregnancy • Persistent fetal circulation • Total anomalous pulmonary veins • Mitral valve stenosis / diabetic cardiomyopathy • Pulmonary hypoplasia / diaphragmatic hernia 1 Fetal closure of the ductus arteriosus 2 Pulmonary artery constriction 5 3 (tricuspid regurge) 4 (commonly seen on echo)
2 1 There are two mechanisms of right to left shunting in the fetus
? How do we know the cause of a newborn’s cyanosis?
You don’t have to use the mind meld, Bones, (All it takes is two sat probes)
95 Does this child have PPHN? 88
90 Does this child have PPHN? 95
Normal pulmonary artery resistance High pulmonary artery resistance How can we reverse persistent fetal circulation?
You don’t need to be a miracle worker, Bones, All you need is a rudimentary understanding of plumbing
Things that reduce Pulmonary Vascular Resistance • Optimal Lung Expansion • High PaO2 • Nitric Oxide • Prevention of acidosis / normal to mildly alkalotic pH • Sedation and when necessary paralysis • Treatment of infection • Things that increase Systemic Blood Pressure • Pressors – Dopamine is your first choice • Fluid boluses (crystalloid) • Colloid as appropriate • Prevention of acidosis / normal to mildly alkalotic pH • Treatment of Infection • Things that can complicate matters • Stimulation – giving a bath, loud noise, unnecessary handling • Spontaneous respirations – not in sync, valsalva effects
POP QUIZ! 86 66 3 hour old male 40 week male , now on CMV 26/4 x 30 on 100%, 35/20 bp, being transported for presumed cyanotic heart disease. You arrive at the outside hospital, see the postductal SaO2, add a preductal SaO2. What are some immediate therapy options that you want to suggest to the transport physician when you call?
89 82 Now what are you going to do?
93 89 Anything else?
Is this child stable to transport? 98 94 When is a child too unstable to transport?
Sometimes we must endeavor to be both, Bones, Judgment is required to discern which vocation should predominate in any given clinical case
Knowing when to stabilize ad nauseum and when to “grab and go” is part of the art of transport medicine. Particularly when it comes to a disease like PPHN. There are some children who simply are not going to get substantially better because they have fixed or severe acute limitations to their physiology (pulmonary hypoplasia, sepsis, or an in utero closure of the ductus). In these cases, the basic modes of stabilization should be implemented and then the child may need to be quickly transported before they deteriorate further. In other cases, if a trend of clear improvement is evident with interventions, it may be more prudent to optimize stabilization before transport. The art of transport medicine is stretched thin in making the right decision with each patient who has PPHN. There are a few pearls that can facilitate decision making, in particular the grab and go.
Fetal hemoglobin holds onto oxygen better than adult hemoglobin (like Vulcan blood) and so infants with PPHN will still have some O2 delivery to their tissues at lower PaO2s. Because infants with PPHN have not transitioned, they are still used to fetal oxygenation levels. Maternal Blood Fetal Blood Vulcan De-oxygenated Blood
If you are transporting one of the more unstable PPHN patients you may have difficulty maintaining adequate oxygenation with conventional ventilation. Unless your ventilator is a JET (or has a positronic brain), a transport clinician is sometimes faced with a Kobayashi Maru type scenario (a seemingly unsolvable dilemma). The problem is how to maintain oxygenation in a child who has little or no pulmonary perfusion.
1) The first and most important thing is to NEVER give up! 2) The second most important thing is to use all the information at your disposal and to continue stabilization throughout the transport. 3) The third thing is to do what works. In some cases, high frequency, hand bagging with intentional breath stacking will result in sufficient optimization of lung volumes and transient respiratory alkalosis – buying you oxygenation and time to get through the transport. Each PPHN case is different and will have a different “sweet spot”.
The Sweet Spot is the constellation of variables (blood pressure, ventilation settings, oxygen requirement, need for nitric oxide, need for alkalinization, etc.) at which a child with PPHN begins to show clear evidence of improved oxygenation. In simple terms, it is when the plumbing is working correctly. Once you find the sweet spot, you want to figure out which variables most strongly contribute to that stability and try to keep them optimized during the transport.
Resistance is Futile! time for another POP QUIZ You are transporting a 38 week old, 3.5 kg male with a left-sided diaphragmatic hernia. Pre and postductal sats have been 95 and 80 respectively. BP 55/35, CMV 29/5 x 40 @ 100% on NO and 8 mg/kg/min of dopamine. You are half way through the transport when the alarms start to go off. The sats plummet to 65 and 60, the BP is 35 over 20, there is chest rise although it appears asymmetric…. rise is better on the right.
Now you’ve done it! You’re sats are 40 and undetectable. Your pressures are 22 and 10. The kid’s color is aquamarine. I don’t know what you’re doing wrong, but whatever it is, you need to do stop and do something right. What else could be causing this sort of catastrophic change and what can you do to keep this child alive until you can get to ECMO?
Remember that you can call for help. These are the worst possible cases to trouble shoot. In nearly every case, a nurse practitioner will be there with you. Even so, sometimes it is the junior person who thinks of the right answer, or who asks the right question… or says, “do you think we should call and ask for advice?” The key to trouble shooting complex patients is to keep your mind engaged and to keep sifting through the data in front of you. Don’t let your brain get frozen. “PLEASE STATE THE NATURE OF THE MEDICAL EMERGENCY”
WHAT TO TELL THE PARENTS i.e. how scared should they be when you’re done talking? • Most patients with idiopathic PPHN do not have to go on ECMO (because of NO). • Those who do go on ECMO without severe hypoxic insult have good neurodevelopmental outcomes. • Diaphragmatic hernias are different, it depends on the size of their lungs / lesion. • About 1/3 of diaphragmatic hernias die, despite aggressive therapy, but the outcomes of survivors are good (from a neurodevelopmental point of view). • All patients with PPHN have increased risk of late onset high frequency hearing loss. • The primary risk for neuromorbidity and death is prolonged hypoxia prior to stabilization in an ECMO center (doesn’t that make you feel better?).
Course Outline: I. Causes of Pulmonary Hypertension a. persistent fetal circulation b. cardiac strain or failure, cardiomyopathy c. closure of the ductus in fetal life d. pulmonary hypoplasia II. Immediate management of persistent pulmonary hypertension in the newborn period a. a word about pre and post ductal saturations b. optimal ventilation / oxygenation c. optimal systemic blood pressure d. sedation / paralyzation III. Management in the transport environment a. nitric oxide b. non-acidosis versus alkalinization c. electronic monitoring IV. Overall Goals for a transport team short term versus long term goals - survival, long term hearing, stability to ECMO You humans are pathetic, if you just had spiracles and trabechulae, instead of lungs, your larvae would never get PPHN.
