FETAL AND NEONATAL HEMODYNAMICS:

A FOCUS ON ECHOCARDIOGRAPHIC ASSESSMENT

Pulmonary circulation***

Laurent Storme, CHRU de Lille, FRANCE

1

Université de Lille

Outline

1. Why to assess pulmonary circulation ?;• Severe respiratory failure• Mechanism of shock

2. How to assess pulmonary circulation ?• Clinical examination;• Chest X-ray• Echocardiography

3. Particularities in Congenital DiaphragmaticHernia

Respiratory failure

With severe hypoxemia

Hypoxemia

= R-L shunt

= « venous admixture »

100%60%

PaO2(mmHg)

45

Shunt=0 %

Shunt=20%

55

Hypoxemia

Parenchymal diseaseIntrapulmonary shunt

PPHNExtrapulmonary shunt

LA

LV

RA

RV

PA

AlveoliAlveoli

Principles of management

« Alveolar recruitment »

• Surfactant No surfactant

• mean airway pressure mean airway pressure

• Permissive hypercapnia Normalize PaCO2• Worsens with fluid/catecholamines Improves with fluid/Catecholamine

• Low NOi High NOi

« Vascular recruitment »

LA

LV

R

A

RV

PAPV

LA

LV

R

A

RV

PAPV

AlveoliAlveoli

Crit Care Med. 2007;35:1741-8

PVR

Right

heart

Ductus arteriosus

Systemic

blood flow

Left

heart

PA Aorta

pulmonary flow

Obstructive shock

http://www.rivendell-peds.com/lungs.jpghttp://www.rivendell-peds.com/lungs.jpg

Outline

1. Why to assess pulmonary circulation ?;• Mechanism of severe respiratory failure• Mechanism of shock

2. How to assess pulmonary circulation ?• Clinical examination;• Chest X-ray• Echocardiography

3. Particularities in Congenital DiaphragmaticHernia

LA

LV

RA

RV

PA

AlveoliAlveoli

• Anamnesis : No antenatal steroids PROM

• GA : Premature Full-term

• Etiology : HMD Infection, CDH

• O2 need : Stable Highly fluctuating

Pre- Post-ductal

SpO2 gradient

Clinical

Assessment

Of respiratory

failure

LA

LV

RA

RV

PA

AlveoliAlveoli

Intrapulmonary shunting Extrapulmonary shunting

X-ray

Assessment

Of respiratory

failure

FO

DA

LV outflowSkinner JR et al, Arch Dis Child 1999; 80: F81-7

LPA velocitiesWalther FJ et al, Pediatrics 1992; 90: 899-904 Rozé et al, Lancet 1994;344: 303-5Gournay Vet al. Acta Paediatr 1998; 87:419-23

Superior vena cava flow

RV outflow

Echocardiographic assessmentof hemodynamics : flow and velocities

FO

DA DA shunting

Inferior vena

cava diameter

Tricuspid regurgitation

Echocardiographic assessmentof hemodynamics : pressures

FO shunting

Pulmonary regurgitation

Septum position

FO

DA

• Tricuspid annular plane systolic excursion (TAPSE)

• Peak systolic tricuspidannular velocity

Echocardiographic assessmentof hemodynamics : function

• RV-myocardial performance index (Tei)

Septum position

• Speckle tracking

But is it really useful ?

But adverse effects of stress on PVR !

0.4

0.6

0.8

1.0

1.2

-20 0 20 40 60 80 100 120 140

Time (min)

PV

R(m

mH

g/m

L/m

in)

suf+formol (n=6) formol (n=8)

Stress

Stress

V Houfflin et al, Am J Physiol, 2005

PVR

Stress

Stress + analgesia

Echocardiographic assessment : in 3 views !

Parasternal short axis Parasternal long axis Suprasternal

from 0.25 to 0.35 m.s

Artère

Pulmonaire

Gauche

Para-mediastinal

short axis view

To assess

the pulmonary

circulation

PA

DA

LPA

Ao

Rozé, Lancet 1994

Gournay, Acta Paediatr 1998

Mean velocities

PA

DA

LPA

Ao

Para-mediastinal

Short axis view

To estimate Aortic blood flow

Suprasternal view

DA

LVO

0.25 to 0.35 m.s

0.25 to 0.35 m.s

Mean Ao Velocity

Rozé, Lancet 1994

Gournay, Acta Paediatr 1998

EDD LV :

14 to 18 mm

At term

LA/Ao :

1 0.2

To evaluate volemia

Para-mediastinal

Long axis view

SF LV = (EDD – ESD)x100/EDD = 30 to 40 %

To evaluate contractility

Para-sternal long axis view/TM

ESD EDD

Anaïs / Meconial aspiration syndrome

• Severe respiratory failure:

– Intubated / ventilated : P 24/4 cmH2O, RR=60 c/min,

– FiO2 = 60%,

– Post-ductal SpO2 = 88%, preductal SpO2= 87%,

– PaCO2=55 mmHg

– Art P = 55/35 (42); HR= 155c/min

Mean Velocity in Left PA

= 0.34 m.s

Hypoxemia

Parenchymal diseaseIntrapulmonary shunt

Alveoli

PPHNExtrapulmonary shunt

LA

LV

RA

RV

PA

Alveoli

Mainly intrapulmonary shunting

« Alveolar recrutment »

Alvéoli

PAO2PAO2

shunting

• Surfactant

• Mean Pressure

• hypoxic vasocontriction

At H6 :

• Surfactant;

• HFO :

• Mean Pressure = 18 cmH2O

• Peak to peak = 95 cmH2O

• Improved : FiO2 = 30 %,

At H24 :

• FiO2 = 100%;

• SpO2 pré = 84%, SpO2 post = 80%

• HFO : Mean P = 22; P to P = 110

• pH = 7.26, PCO2 = 54 mmHg

• Blue/grey: CRT >>> 3s

• Art P = 35/28 (30) mmHg, HR= 160

• Lactate = 580 mg/l

• Diurèse = 0

• Unstable +++

Mean Velocity in Ao = O.21 m.s

Mean Velocity in Right PA = 0.15 m.s

Parasternal short axis view

Velocities in ductus arteriosus

FO shunting

RA

RV

LA

LV

DA

Obstructive shock

2 possible mechanisms:

1. LAP : Q pulm

2. RAP : RV failure

PVR

Right

heart

Ductus arteriosus

Systemic

blood flow

Left

heart

PA Aorta

pulmonary flow

Obstructive shock

http://www.rivendell-peds.com/lungs.jpghttp://www.rivendell-peds.com/lungs.jpg

Mean Velocity in Ao = 0.35 m.s

Management:

• iNO = 20 ppm

• Prostaglandin E1

Mean velocity in Left PA = 0.36 m.s

Outline

1. Why to assess pulmonary circulation ?;• Severe respiratory failure• Shock

2. How to assess pulmonary circulation ?• Clinical examination;• Chest X-ray• Echocardiography

3. Particularities in Congenital DiaphragmaticHernia

Ultrasound Obstet Gynecol 2010;35,310

Deprest J, Ultrasound Obstet Gynecol 2010;36,452

LV

en

d-d

iast

oli

c v

olu

mePrénatal Postnatal

CDH

Hypoplasia of

the left heart

Pulmonary Hypertension

PAP = (Qp x PVR) + LAP

Flow

Resistance

Left

Atrial

Pressure

PPHN

PAP =

(Qp x PVR)

+ LAP

PVR

Right

heart

R Ductus Arteriosus

SVR

Systemic flow

Left

heart

Systemic flow = Qpulm + DA flow

+

Violette, full-term, at 12Hrs:

• FiO2=30%, P 22/4 cmH2O, RR=50

• SpO2 pré=92%, postductal=65%

• HR = 122 / min, TcPCO2=58 mmHg

• AoP=55/33 (40) mmHg, CRT

Pulmonary artery pressure = Aortic pressure

Failure of circulatory adaptation :

Persistent Pulmonary Hypertension of the Newborn (PPHN)

Pre- and Post-ductal SpO2 gradient

O2 Delivery =

1.3 x AoFlow x Hb x SpO2

FiO2 should target PRE-DUCTAL SpO2 85-95%

DA

RA

RVLV

PA

RV

RALV

LAAP

Ao

Hypoxemia, but no hypoxia !

Mean blood flow velocities

in Left Pulmonary Artery

= 0.25 m.s

Inhaled NO ??? :

• Recommanded in PPHN (↓ ECMO) ;

• Few CDH cases respond to iNO;

• No evidence that iNO improves outcome (death or ECMO);

• ↑ need for ECMO in CDH !

iNO cannot be recommanded in CDH infants with PPHN as long as preductal SpO2 is

adequate

Lung overinflation

To prevent iatrogenic issues

0.4

0.6

0.8

1.0

1.2

-20 0 20 40 60 80 100 120 140

Time (min)

PV

R(m

mH

g/m

L/m

in)

suf+formol (n=6) formol (n=8)

Stress

Stress

Houfflin. Am J Physiol, 2005Houfflin. Anesth Analg, 2007

PVR

PVR

Dopamine

Jaillard S, Am J Physiol. 2001

Bouissou A, J Pediatr 2008

Painful stimuli

Painful stimuli + analgesiaBenzodiazepine

Take home message:

Appropriate management in severe respiratory failure:• To assess the mechanisms of the respiratory failure (intra or extrapulmonary shunting ?);• To determine the mechanism of the Pulmonary Hypertension:

– High pulmonary vascular resistance ?– Post-capillary PH (Hypoplasia of the Left Heart in CDH) ?– High pulmonary blood flow ?

• To adapt treatment :– Pulmonary vasodilator when high PVR-induced low pulmonary blood

flow ;– Re-open the DA in suprasystemic PH;– « Better is the ennemy of good », in postcapillary PH;

• To prevent iatrogenic issues:• Overdistension of the lung• Deep sedation using midazolam or propofol