Persistent Pulmonary
Hypertension in the Newborn
A Star Fleet Academy
Short Course
Pulmonary
Hypertension
Fetal closure of the
ductus arteriosus
Examples:
NSAIDS during
pregnancy
•
Persistent fetal
circulation
•
Total anomalous
pulmonary veins
•
Mitral valve
stenosis / diabetic
cardiomyopathy
•
Pulmonary
hypoplasia /
diaphragmatic
hernia
1
Pulmonary artery
constriction
5
•
2
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?
Damn it, I’m a doctor! Not a mind reader!
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?
Damn it, I’m a doctor! Not a miracle worker!
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
1.
Optimal Lung Expansion
2.
High PaO2
3.
Nitric Oxide
4.
Prevention of acidosis / normal to mildly alkalotic pH
5.
Sedation and when necessary paralysis
6.
Treatment of infection
Things that increase Systemic Blood Pressure
1.
Pressors – Dopamine is your first choice
2.
Fluid boluses (crystalloid)
3.
Colloid as appropriate
4.
Prevention of acidosis / normal to mildly alkalotic pH
5.
Treatment of Infection
Things that can complicate matters
1.
Stimulation – giving a bath, loud noise, unnecessary handling
2.
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?
Damn it, I’m a doctor! Not a cargo handler!
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
Vulcan De-oxygenated Blood
Fetal 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”.
What is a 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?
1) Most patients with idiopathic PPHN do not have to go on ECMO (because of NO).
2) Those who do go on ECMO without severe hypoxic insult have good
neurodevelopmental outcomes.
3) Diaphragmatic hernias are different, it depends on the size of their lungs / lesion.
4) About 1/3 of diaphragmatic hernias die, despite aggressive therapy, but the
outcomes of survivors are good (from a neurodevelopmental point of view).
5) All patients with PPHN have increased risk of late onset high frequency hearing
loss.
6) 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
You humans are pathetic,
if you just had spiracles
and trabechulae, instead
of lungs, your larvae
would never get PPHN.
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