tingay hfov in the recruitable lung - murdoch children's ... · the recruitable lung! ... spo...

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HFOV IN PRACTICE: The recruitable lung

David Tingay

Ini$a$ng HFOV Preterm Infant

•  28/40 GA •  BW 1 kg •  Intubated at 1 hr •  Paw 12 cmH2O •  FiO2 1.0 •  SpO2 86% •  PaO2 45 mmHg •  PaCO2 55 mmHg

5

10

15

20

25

P aw (c

m H

2O)

Pinitial Paw 14 FiO2 0.8 SpO2 90% PaO2 52 mmHg PaCO2 53 mmHg

HFOV Settings?

Pre-HFOV Questions •  Device? •  Monitoring •  Positioning •  Sedation/ Analgesia/

MR •  Cardiac Support •  PPHN •  Biochemical support

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Favours HFV Favours CMV Cools (PreVILI Group) Lancet

HFOV vs CMV: High Lung Volume Strategy

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High lung volume strategy (HLVS) Tradi$onal defini$on Cochrane database defini$on (at least 2 of):

1. Ini-al use of a higher mean airway pressure than on CMV

2. Ini-al weaning of frac-onal inspired oxygen before mean airway pressure

3. Use of alveolar recruitment manoeuvres


•  28/40 GA •  BW 1 kg •  Intubated at 1 hr •  Paw 12 cmH2O •  FiO2 1.0 •  SpO2 86% •  PaO2 45 mmHg •  PaCO2 55 mmHg

5

10

15

20

25

P aw (c

m H

2O)


HFOV Settings?

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‘Sta$c’ Paw HLVS How do you know you are in the Safe Window?

& Froese CCM 1997

The Open Lung Concept

Lachmann ICM 1990 ‘open the lung, find the closing pressure, re-‐open it and keep it open!’ •  Achieve Lung Recruitment •  Iden-fy the lowest pressure that maintains that recruitment

(OPTIMAL PRESSURE; POPT) •  Exploit the hysteresis of the lung •  Exploit PEEP – an expiratory phenomenon that maintains

recruitment

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Rela$onship between PAW and EELV

PV rela-onship can be mapped at the bedside with PAW

& Tingay et al AJRCCM 2006 & Miedema et al J Peds 2011

Term Infants Preterm Infants


5

10

15

20

25

P aw (c

m H

2O)


Paw 21 FiO2 0.5 SpO2 88% PaO2 60 mmHg PaCO2 70 mmHg

Popen Paw 20 FiO2 0.5 SpO2 93% PaO2 65 mmHg PaCO2 60 mmHg

Paw 16 FiO2 0.7 SpO2 94%

Paw 18 FiO2 0.6 SpO2 95%

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Region of Op$mal Ven$la$on?

& Froese AJRCCM 2002

Inflation Limb

Recruitment is ongoing (inhomogeneity)

At no point can all mechanical causes of VILI be minimised &  Hickling et al AJRCCM 2001 & Jonson ICM 2005

Deflation Limb

Alveolar stability maintained & Albaiceta CCM 2004

Opening pressure > collapsing forces & Rimensberger ICM 2000


5

10

15

20

25

P aw (c

m H

2O)Pinitial


Popen Paw 20 FiO2 0.5 SpO2 93% PaO2 65 mmHg PaCO2 60 mmHg

Pclose Paw 8 FiO2 0.6 SpO2 84% PaO2 32 mmHg PaCO2 49 mmHg

Paw 12 FiO2 0.4 SpO2 95%

Paw 18 FiO2 0.4 SpO2 96%

Paw 14 FiO2 0.4 SpO2 95%

Paw 10 FiO2 0.4 SpO2 90%

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Relationship between PAW, Lung Volume and SpO2

•  SpO2 reliably identified TLC (overdistension) and CCP (collapse)

•  SpO2 cannot precisely delineate between small volume state changes

& Miedema J Peds 2011

& Tingay AJRCCM 2006


5

10

15

20

25

P aw (c

m H

2O)Pinitial


Popen Paw 20 FiO2 0.5 SpO2 93% PaCO2 60 mmHg

Pclose Paw 8 FiO2 0.6 SpO2 84% PaCO2 49 mmHg

Popt Paw 11 FiO2 0.4 SpO2 92% PaCO2 41 mmHg

Paw 20 FiO2 0.4 SpO2 95%

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OLV during HFOV in newborn infants Rimensberger et al Pediatrics 1999

–  LVO (If FIO2 >0.4): 1-‐2 cm H2O Paw steps every 1-‐2 mins UNTIL FIO2≤0.4 (max Paw 25 cm H2O)

–  THEN Paw decreased un-l FIO2 ≤0.4 and PaO2 ≥60 mmHg Less ven-lator days, Lower oxygen dependency, Less CLD Transient high Paw is well tolerated, even in preterm infants

DeJaegre et al AJRCCM 2006 Similar LVO strategy:

–  Pmax FIO2 at CDPOPT ≤ 0.25 before surfactant FIO2 at CDPOPT ≤ 0.25 in 75% and ≤ 0.3 in 98% An aggressive recruitment strategy using oxygena?on to guide the recruitment process is feasible and safe during HFV in preterm infants with RDS.

Tingay et al AJRCCM 2006 OLV resulted in op-mal SpO2, TcCO2, VT and Crs Op-mal Paw iden-fied ager aggressive recruitment at CCP+2 – 4 cm H2O

The Amsterdam experience

An open lung ventilation strategy using oxygenation to guide the recruitment process is feasible and safe during HFV in preterm infants with RDS.

n = 103

FIO2 at CDPOPT ≤ 0.25 in 75% and ≤ 0.3 in 98%

TcCO2 was reduced by 9 mmHg after optimal recruitment (pre-surfactant)

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5

10

15

20

25P a

w (c

m H

2O)Pinitial


Popen Paw 20 FiO2 0.5 SpO2 93% PaCO2 60 mmHg

Pclose Paw 8 FiO2 0.6 SpO2 84% PaCO2 49 mmHg

Popt Paw 11 FiO2 0.4 SpO2 92% PaCO2 41 mmHg

Paw 20 FiO2 0.4 SpO2 95%

J Clin Invest 1959. 38:2168

PV rela$onship influences lung mechanics

Atelectasis → CRS low = PCO2 high

↑ CRS = PCO2 lower

Overdistension → CRS low + ↑ dead space = PCO2 high

↑ CRS + ↓ deadspace = PCO2 lower

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Is Oxygena$on the best marker of the op$mal EEV?

Paw (cmH2O above Pcl)

PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

Vol

ume

chen

ge (

t0 -

t1)

(%)

-35

-30

-25

-20

-15

-10

-5

0

5

VentralDorsal

*

*

PAW (cmH2O above PCL)


VT

HF (

mL/K

g)

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

XR

S (

cm

H2O

*s/L

)

-90

-80

-70

-60

-50

-40

-30

-20

-10 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

VL (

% V

L a

t P

max)

30

40

50

60

70

80

90

100

110 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

Sp

O2/F

iO2

250

300

350

400

450

500

Pmax

Pstart

Pstart

Pmax

Pmax

Pstart

A

B

C

Pmax

Pstart

D

PAW (cmH2O above PCL)


VT

HF (

mL

/Kg)

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

XR

S (

cm

H2O

*s/L

)

-90

-80

-70

-60

-50

-40

-30

-20

-10 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

VL (

% V

L a

t P

ma

x)

30

40

50

60

70

80

90

100

110 PCL PCL+2 PCL+4 PCL+6 PCL+8 PCL+10

Sp

O2/F

iO2

250

300

350

400

450

500

Pmax

Pstart

Pstart

Pmax

Pmax

Pstart

A

B

C

Pmax

Pstart

D

& Zannin Ped Res 2014

PV rela$onship influences lung mechanics

Tingay et al CCM 2013

6 8 10 12 14 16 18 204.0

4.5

5.0

5.5

6.0

7.0

7.5

8.0

8.5

CDP (cm H2O)

Impe

danc

e Vt TcpC

O2

Miedema et al. ERJ 2012

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The Op$mal Safe Window The region of the Defla/on Limb >Pclose that balances op/mal oxygena/on and lung mechanics

0 25 50 75 100

0

50

100

Paw (%)

V L (%

)

Pmax

Pfinal

SpO2

Region of optimal volume

TcCO2

MVHF

VTao

VTRIP

Opt

imal

Paw

ra

nge

Pinitial

Safe Zone

Tingay et al CCM 2013

Smolich et al 2014 PSANZ (Preterm Lambs)

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How long un$l EEV stablises aRer a Paw change? Preterm infants

Miedema et al ICM 2012

Tingay PhD data

How long un$l EEV stablises aRer a Paw change? Term infants

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But, I must give surfactant! Op$mum point of ven$la$on may change

•  N=15 preterm infants •  EIT measurements during OLV before and ager surfactant

administra-on •  Surfactant administra-on:

–  Increased EELV by 61±39% –  Improved distribu-on of ven-la-on:

-  V:D ra-o 1.16 vs 0.81 –  Lowered the CCP:

-  16.4±3.1 vs 10.4±2.4 cm H2O

& Miedema et al AJRCCM 2011

PEEP PIP

Volu

me Surfactant

Setting the Frequency - Considerations

•  Frequency influences the stroke volume •  The time constant of the lung determines frequency •  Lung disease and size determines time constant •  BUT there are risks of going too high and too low in the RDS lung •  Compliant lungs - marked damping of HFOV pressure •  Potential for barotrauma in the poorly recruited lung at low frequency

Pillow et al AJRCCM 2001

↑Raw

↓C

↑Raw↓C

Frequency (Hz)

Pea

k C

arin

al P

ress

ure

10 20 30

Venegas & Fredberg Crit Care Med 1994

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SeVng the Frequency – Prac$cal guide Suggested ini/al maximum frequency seVngs

PIE in evolution

}

Established PIE with high FiO2 and CO2 retention

}

} Preterm HMD (Dräger BL+VN)*

Meconium aspiration syndrome } }

Preterm HMD

Term lung disease

}

15

14

13

12

11

10

9

8

7

6

5

Weaning to extuba$on

Options: Preterm Term

Wean to low PAW and extubate directly from HFOV √ √

Wean to low PAW, brief period of low rate SIMV (or ETCPAP), then extubate

√

When lung disease improved transfer to synchronized IMV and extubate when able

√

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At what HFOV seVngs can we extubate?

FiO2 < 0.3 PAW 6-8 cm H2O ΔP 10-15 cm H2O WOB satisfactory

pH > 7.25

Preterm van Velzen A et al PCCM 2009 •  214 preterm infants (29.5 ± 2.5

wk, BW 1300 ± 480 g)•  Early OLV HFOV•  E x t u b a t i o n f r o m H F O V

attempted at a median age of 62 hrs

•  Successful in 193 (90%) of the infants.

•  PAW at the time of extubation 6.8 ± 1.6 cmH2O

At what HFOV seVngs can we extubate?


pH > 7.25


pH > 7.25

Preterm Term

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Summary •  In the atelecta-c lung, lung recruitment can be individualised

using an open lung strategy •  Watch your pa-ent, use the clues available and adapt

EEV

SpO2

Mechanics

‘From Art to Science’

HFOV in practice – the recruitable lung David Tingay/Andreas Schibler HFOV in the non-recruitable lung Peter Dargaville

Day 2 Session 2: Putting HFOV into clinical practice

Old and new concepts in the application of high frequency oscillatory ventilation

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Pressure cost of ven$la$on Peak alveolar distension

( ) TLCVVD TEEalv /+=Normal RDS

PEEP (cmH2O)

f (Hz) PEEP

(cmH2O)

f (Hz)

Dalv Dalv

Venegas J & Fredberg J, Crit Care Med, 1994

Shaded regions = ‘safe’ Paw & Fr options (Peak Dalv < 90% TLC) RDS = less rood for error in choice of Paw and Fr

Hysteresis For any given Pressure there is a range of volumes that can exist Thus, for any given Volume there is a range of pressures that can achieve it That pressure will always be lower on the defla-on limb, because Pcl < Pop

Crotti et al AJRCCM 2001

Gattinoni et al AJRCCM 2001

tingay hfov in the recruitable lung - murdoch children's ... · the recruitable lung! ... spo...

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