Transcript Pulmonary blood flow

Catherine Bull M.S.N, P.N.P-C
Clinical Coordinator, Pediatric and Adult Congenital Cardiac Surgical Services
Department of Cardiothoracic Surgery
NYU Medical Center
Qs
Qp
 Pulmonary blood flow
 Systemic blood flow
~ 1 cup
~ 1 cup
Qp:Qs ratio is the amount of blood going to the lungs
compared to the amount of blood going to the body.
Qp : Qs
(LUNGS : BODY)
Qp : Qs
1:1
Blood flow to the body or the lungs is not 100%
ductal dependent
Transposition of the
Great Arteries
Total Anomalous Venous return
Truncus Arteriosus
NORMAL

TGA :
 Aorta arises from
the anatomic RV
 PA arises from the
anatomical LV
•
•
Parallel circulations
Mixing can occur at
PFO, PDA or VSD
• Most mixing occurs at
the PFO
•
Without a mixing:
– cyanosis, hypercarbia,
tachypnea, tachycardia
and acidosis may occur
n
NORMAL

To increase
SaO2 you
must increase
mixing:
 PGE to open
duct
 BAS
 Volume
 Oxygen
PDA
PFO

Arterial Switch
 The aorta and the PA are
transected and the
coronary arteries are
removed.
 The aorta and the
coronary arteries and
attached to the neoaortic
root
 PA is attached to the
neopulmonary root

Decreased LV function
 Coronary ischemia
 Nitroglycerine/Heparin
▪ Usually a surgical problem
 In older patients with IVS whose LV only exposed
to pulmonary pressures pre-operatively


Decreased cardiac output
Arrhythmias


Failure of pulmonary veins to
connect to the to the LA
Blood from both the systemic
and pulmonary venous
systems return to the RA
 the RA, RV & pulmonary arteries
enlarge to compensate for the
increased volume

An ASD is essential for CO and
always present
NORMAL
NORMAL

Supracardiac: pulmonary veins attach to SVC.
NORMAL

Cardiac: pulmonary veins attach directly to the
heart via RA or coronary sinus
NORMAL

Infracardiac: pulmonary veins attach below the
diaphragm. Prone to obstruction.
Supracardiac
•
Unobstructed:
– May be asymptomatic at first
– CHF, FTT & frequent upper
respiratory infections will occur
•
Obstructed:
― Profound cyanosis within the
first few hours of life
― Typical “ground glass” CXR
― No PGE
― Surgical Emergency
Infracardiac

CXR:
 Typical “ground
glass” appearance
of lung fields
 Small heart
Attach pulmonary vein
confluence to
posterior LA and
close the ASD
Ligate the vertical vein
•Create a large ASD
and baffle veins from
the RA to LA
Unroof coronary
sinus and baffle
pulmonary venous
return to the LA
•Attach pulmonary vein
confluence to posterior
LA
•Ligate the vertical vein
•Close the ASD
Low cardiac output:



Noncompliant LV. Treated w/ inotropes.
Avoid aggressive volume overload-unresolved LA
hypertension & PHTN.
PHTN:


r/o pulmonary venous obstruction. Ventilation, O2, NO &
sedation to decrease PVR.
Respiratory failure:



Due to obstructed veins preop and resultant pulmonary
vascular congestion.
Treated with mechanical ventilation, paralysis, sedation,
PEEP & possibly ECMO.
Re obstruction


occurs in 10% of patients-usually obstructed infracardiac
type
NORMAL


CHF, mild cyanosis &
FFT within the first
month of life.
Can develop
pulmonary
hypertension by 3
months.
The pulmonary arteries
are excised from the
truncus
 RV to PA conduit placed
 VSD is closed in a manner
in which the truncal valve
recieves blood from the
left ventricle


PHTN:
 preop overcirculation results in PA pressures=>Paralyze,
sedate, O2 and NO.

Low CO:
 RV dysfunction=> volume (need a high CVP), inotropes &
vasodilators.

Cyanosis:
 RL PFO =>will resolve with RV function.
Pulmonary blood flow is ductal dependant
Regular
Pulmonary Atresia
Real Pulmonary Atresia
Te t r a l o g y o f F a l l o t
Pulmonary
Atresia
w/ Intact
Ventricular
Septum
Pulmonary Atresia
w/ MAPCA’s
Tricuspid
Atresia

TOF is characterized by 4
cardiac anomalies:
 Ventricular septal defect
 Pulmonary stenosis or
pulmonary atresia/right
ventricular outflow tract
obstruction (RVOTO)
 Overriding aorta
 Right ventricular
hypertrophy
NORMAL

Hemodynamics depends on the amount of PS and
the size of the VSD
 Severe PS:
Cyanotic
▪ RL shunt
▪ Qp<Qs
 Mild PS:
▪ LR shunt
▪ Qp>Qs
▪ CHF
Pink Tet


Patch closure of VSD
Relieve RVOTO
 Resect muscle below the
valve
 Enlarge the pulmonary
artery above the valve
OR
 transannular patch with
removal of valve
•
•
•
•
•
RV dysfunction
– Inotropes
– May have pleural effusions (esp. right) and ascites
Junctional Eptopic Tachycardia
– PREVENTION
– keep HR low with cooling, no chronotropic drugs, sedation
– Amiodarone
Cyanosis
– due to right to left shunt across PFO if present
Pulmonary insufficiency
– all patients with transannular patch
Residual VSD
– not well tolerated
•
Residual RVOTO
– well tolerated


Pulmonary valve &
main pulmonary artery
are atretic
Pulmonary blood flow
is supplied by
TOF/PA
 PDA (most common)
 multiple
aortopulmonary
collateral arteries
(MAPCAs)
TOF/PA w/ MAPAC’s

Blalock-Taussig
Shunt followed
by full repair
later in infancy
Pulmonary valve atresia with
no VSD
 Hypoplastic RV (Variable)

 Size of the RV is determined by
the size of the TV


High RV pressure
RV sinusoids (Variable)
 May form due to high RV
pressure.
 Steal coronary blood flow from
CA
NORMAL
RV Sinusoids

Need to do 2 things: establish pulmonary
blood flow and get the RV to grow
 Pulmonary valve balloon angioplasty
▪ Works best when the leaflets of valve are only fused
 BTS
 Transannular patch

2 Ventricle Repair (Adequate RV without sinusoids)
 Balloon angioplasty
 +/- BTS

1 ½ Ventricle Repair (Borderline RV +/-sinusoids)
 +/- Balloon angioplasty
 BTS
 +/- Transannular patch

Single Ventricle Repair (Inadequate RV +/- sinusoids)
 BTS

Borderline RV +/-sinusoids:
 BTS & transannular patch to
allow pulmonary
insufficiency and
subsequent RV growth.
▪ Adequate RV growth: complete
repair
▪ Inadequate RV growth:
Bidirectional Glenn procedure
(1 ½ ventricle repair)
NORMAL
The tricuspid valve is
absent w/ no
communication
between the RA and RV
 Results in RV and PA
hypoplasia and a single
left ventricle


No VSD, PA, hypoplastic RV
 Pulmonary blood flow is ductal dependant

Small VSD, hypoplastic PV, hypoplastic RV
(most common)
 Pulmonary blood flow is ductal dependant

Large VSD, small to adequate PV & RV
 Qp:Qs is variable
Cyanosis, hypoxemia and metabolic acidosis
usually occur within the first few days of life if
pulmonary blood flow is not adequate and the
PDA closes. Qp<Qs
 Management strategies should be aimed at
balancing pulmonary and systemic blood flow
to maintain Qp=Qs.


Blalock Taussig
Shunt
 Pallative shunt
between the right
innominate artery
and the RPA that
provides pulmonary
blood flow.
 Variable Qp:Qs
Blood flow to the body is ductal dependant
Coarctation of the Aorta
Interrupted Aortic Arch
Hypoplastic Left
Heart Syndrome
NORMAL
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Systemic blood flow is ductal
dependant
Blood to the upper body comes
from the LV & aorta: pre-ductal
sats are higher
Blood to the lower part of the
body comes from the PA and
PDA: post-ductal sats are lower
Decreased peripheral perfusion &
metabolic acidosis if duct closes
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Type A= away
Type B
Type C= close

End-to-end anastomosis w/
PDA ligation
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Pulmonary
hypertension
Issues related to
DiGeorge Syndrome
Recurrent laryngeal
nerve palsy
Pherenic nerve damage
Recurrent stenosis at
site of repair

Underdevelopment of
the left side of the heart
due to:
1.
2.
3.
4.

Mitral stenosis/atresia
Aortic stenosis/atresia
Hypoplastic left ventricle
Hypoplastic aortic arch
100% of systemic blood
flow is ductal dependent
NORMAL
NORMAL
The amount of blood flow
to the pulmonary and
systemic circulations
depends on the relationship
between SVR & PVR
 As PVR falls blood will
naturally go to the lungs &
away from the body

•
1st few days of life: well appearing baby
(Qp=Qs) Sat 80%
 Pink and warm
•
As the ductus closes blood flows into the lungs
resulting in CHF and decreased cardiac output.
(Qp>Qs 3:1) Sat >90%
– Ashen, tachypeanic, cool, difficulty feeding
•
There is progressive deterioration resulting in
pulmonary edema and cardiogenic shock.
(Qp>>Qs 5:1)
– Metabolic acidosis, cold & gray

Prevent the natural progression
 Lower the systemic vascular resistance
 Give extra circulating blood volume

The sick neonate requires aggressive
intervention
 Goal is to re-establish systemic perfusion (Qp:Qs=1)
and provide blood flow to the systemic organs
▪ Lower the systemic vascular resistance
▪ Give extra circulating blood volume
1. Creation of
Neoaorta
2. Oversew
MPA
3. Atrial
septectomy
4. BTS/Sano
BT Shunt
Sano Shunt
Patient Management

Systemic blood flow is grossly indicated
by Lactate and BE/BD on ABG.
 BD < -2 or Lactate > 2 indicates metabolic
acidosis and too little systemic blood flow.
 BE > 0 or Lactate < 2 indicates adequate
systemic blood flow.

Pulmonary blood flow is indicated by
PaO2 on ABG.
 PaO2 > 50 indicates too much PBF
 PaO2 < 30 indicates too little PBF

O2 Sats = pulmonary blood flow
(gross measurement)

O2 Sat 80%= Qp:Qs of 1:1
 Sats > 90%: too much pulmonary blood flow
 Sats < 75%: too little pulmonary blood flow

O2 Sats in patients with single ventricle
physiology tell you how much blood is
going to the lungs-not necessarily how
well the lungs are working.
(ABG sat)
(VBG sat)
Ao Sat
SVO2
Qp/Qs= 80% 100% -
60% =20 =1
80% 20 1
PV sat
PA sat
(Assumed)
(ABG sat)

Not enough cardiac output
 Sats>90%
 Poor peripheral perfusion
 Cool extremities
 Tachypnea
 Diaphoresis
 Poor weight gain
 “Norwood gray”

Too little pulmonary blood flow
 Sats < 75%
 Bounding pulses
 Cyanotic with good perfusion
 “Blue is better than gray!”

What affects Qp:Qs?
 Systemic vascular resistance
(SVR)
 Pulmonary vascular resistance
(PVR)
Always Remember BLOOD FLOWS THE
PATH OF LEAST RESISTANCE
•
Too little cardiac output
Lactate > 2.5, Sats>90%, PaO2 > 50
•
 decrease the SVR or increase PVR
Too little pulmonary blood flow
Sats<75%, PaO2 < 30
 decrease the PVR or fill the tank
*be very careful of increasing SVR in patients with
single ventricle physiology— DON’T DO IT!


The easiest way to increase CO is to
vasodilate the patient
Other ways to manipulate PVR & SVR
 Temperature
 FiO2
 Ventilator changes
 Sedation
Factors that  PVR
Factors that  PVR
Hypoxia PaO2 (NITROGEN)
Hypoventilation PaCO2
Hypothermia
Agitation
Hyperoxia PaO2 (OXYGEN)
Hyperventilation PaCO2
Normothermia
Analgesics
Factors that  SVR
Hypothermia
Agitation
Catecholamines (high dose dopa,
epi)
NO
**Factor that  SVR**
Normothermia
Analgesics/sedation
Vasodilators (Milrinone)

In all post-op patients w/ single
ventricle physiology you MUST do
two things ….
1. Ask yourself “is the patient warm, well
perfused and non-acidotic?”
If so then STOP and revaluate whatever you
where going to do next.
2. Relearn how to read an ABG
– 7.31/35/58/-4; lactate :5 like this?
– lactate :5; -4/58/35/7.31 or like this?
•
•
•
•
•
•
•
Sat 75-90%, PaO2 35-50, BE > 0,
Lactate < 2.5
Investigate, correct and
reinvestigate any metabolic
acidosis
Afterload reduction:
• Milrinone 0.25-0.75 mcg/kg/min
Volume:
• Based on perfusion and acid base status
• Anticipate volume requirement
Hgb= 13-15…..always above 11
Normal sinus rhythm
Normothermia to slightly cool but
not hot

Avoid unnecessary noxious stimuli
 No baths or weights on night shift
 Cluster cares
 No excessive crying or IV sticks



Normothermia
Avoid dehydration
Weight gain- calories, calories, calories….
 3KG baby needs 60 cc q 3h of 24 cal/oz formula to achieve 130
cal/kg/day- we do not always get here prior to DC
 NG/PO feedings to achieve 10g/day wt gain
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Acidosis
Arrhythmias
Anemia
Sats > 93%
Sats < 70%
Dehydration
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A ventricle that is working double time
Variable cardiac output
Increased caloric requirement/difficulty
feeding
Tachypnea
A need for close supervision/follow-up
A risk for sudden death
•
Stressful hospitalization
– Fetal dx: long time to think and web surf
– Antenatal dx: no time to prepare
– Long hospitalization: 14-36 days
•
Transition home
– Most fragile between the 1st and 2nd stage
• Must have scale and pulse ox prior to DC
– 20% risk of death prior to the second stage
– Close follow-up by NP’s in clinic in addition to Nutritionist
•
Anticipation of future surgeries

High Risk Patient population:
 Single Ventricle requiring staged repairs
 Hybrid procedures and palliations
 MBT shunts
 PA, VSD, MAPCAs
 Other complex lesions including heterotaxy
syndrome


Approximately 7 to 15% of these infants will
die unexpectedly at home before Stage 2.
Possible Causes






Coronary artery obstruction or spasm
Aortic arch obstruction
Low cardiac output
Arrhythmia
Shunt thrombosis
Sepsis or infection

Predictors
 Intact atrial septum
 Older age at the time of surgery
 Post op arrhythmias
 Airway complications
 Decreased ventricular fx pre and post op
 Anatomic subtypes
▪ Aortic atresia
▪ Small ascending aorta diameter



Infants with Complex Single Ventricle have
significant growth failure after Stage I
palliation.
Only 3.6% at or above 50th percentile in
weight at the time of Stage II palliation (Atz et
al, 2004)
Feeding difficulties and inadequate nutrition
can strongly influence outcomes!
All Single Ventricle
patients go home with
a scale and pulse ox
 Family keeps daily log
of feeding, weight and
O2 saturations
 Monitored by NPs
either by phone or in
high risk clinic


Family has “red flags”
to call for:
 Weight loss: 30 grams of
weight in one day
 Lack of weight gain: 20
grams of over 3 days
 O2 sats drop below 70%
Weekly visits after discharge x 4 weeks
Every other week visits until Pre-Glenn Cath
(~3-4 months of age).
 Special attention to Sats, weight, vomiting,
diarrhea, feeding difficulties, URI
 Monitor

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
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Pulse oximetry
Weight
BP
Echocardiogram as necessary
Monthly
 Monitor EKG, Chest X-ray

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Reduce interstage mortality to 0%
Improved nutritional status and weight gain
will positively influence timing of Stage II
palliation and outcome of surgical treatment.