nava-korzyścidla...

2017-10-05

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NAVA-korzyści dla noworodka

Jan Mazela

Poznan University of Medical Sciences

Poznan, Poland

DISCLOSURE

• No conflict of interest related to this topic

POZNAŃ POZNAŃ andandWIELKOPOLSKAWIELKOPOLSKA REGIONREGION

EUROPE POLAND

WIELKOPOLSKA

REGION

POZNAŃ

••4 4 mlnmln level III center (7 level II and 24 level I)level III center (7 level II and 24 level I)••773300 deliveries00 deliveries••400 400 outbornoutborn admissionsadmissions••900 NICU admissions900 NICU admissions••337 NICU beds7 NICU beds

Poznan Poznan UnivUniv of Med Sciences NICUof Med Sciences NICU

2017-10-05

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• Intro/basics

• How it looks/how it works?

• Status quo in the literature

• How to tune-up NAVA ventilation

• Ventilation Induced Diaphragm Dysfunction

Comparison of TriggeringMethods

Method Advantages Disadvantages

Impedance No added dead space, noninvasive Poor sensitivity, many artifacts

Pneumatic Capsule Rapid response, no extra dead

space, leak tolerant

Positioning is critical, no longer

commercially available

Pressure No added dead space, leak

tolerant

Poor sensitivity, long trigger

delay, high WOB

Airflow Very sensitive, rapid response Added dead space, leak

sensitive

Diaphragm EMG - Edi Sensitive, most rapid

response, leak tolerant

Requires careful positioning

of probe

State of the art in mechanical ventilation, Keszler, J of Perinatology (2009) 29, 262-75

NAVA

neurally adjusted

ventilatory assist

How NAVA works

The ventilator generates the peak inspiratory pressure

based on the amount of electrical activity generated

by the diaphragm

The PIP is generated until the electrical activity

decreases by 40 to 70% and then the breath is

terminated

The baby therefore determines the peak inspiratory

pressure, the inspiratory and termination time for

each breath and the respiratory rate

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NAVA Terminology

EADi – Electrical Activity of the Diaphragm– Abbreviated as Edi

Edi Peak - peak electrical activity tells you about the neural inspiratory effort

Edi Min – tonic electrical activity believed to play a role in preventing de-recruitment of the lung (Allo

2006, Emeriaud, Beck 2008)

Edi trigger – the change in Edi needed to trigger the ventilator to deliver a breath

NAVA Terminology

NAVA level - Conversion factor that translates the Edi from an electrical signal to a peak inspiratory pressure (PIP)

Calculated by:

PIP = NAVA level x(Edi peak – Edi min) + PEEP

NAVA Terminology

PIP = NAVA level x(Edi peak – Edi min) + PEEP

NAVA level 2 Edi peak 12 Edi min 2 PEEP 5

PIP = 2 x (12 – 2) + 5 = 2 x (10) + 5 = 25 mmHg

Brainstem senses decreased pH or increased pCO2 – wants to increase tidal volume – increases the electrical signal to the diaphragm


PIP = 2 x (15 - 2) + 5 = 2 x (13) + 5 = 31 mmHg

NAVA Terminology

PIP = NAVA level x (Edi peak – Edi min) + PEEP


PIP = 3 x (12 – 2) + 5 = 3 x (10) + 5 = 35 mmHg

Brainstem senses increased pH or decreased pCO2 – wants to decrease tidal volume – decreases the electrical signal to the diaphragm


PIP = 3 x (8 - 2) + 5 = 3 x (6) + 5 = 23 mmHg

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Conventional Ventilation

Patient Controls using Flow Trigger:

Initiation of Breath Rate (in some modes)

Ventilator Controls:

Peak Pressure or Tidal VolumeInspiratory TimeTermination of BreathPEEPMinimum RateFiO2

Synchrony:

Only for Initiation of BreathAsynchronous for Many BreathsFalse Triggering

NAVA Ventilation

Patient Controls using Neural Trigger:

Initiation of BreathInspiratory TimeRatePeak PressureTermination of Breath

Ventilator Controls:

FiO2

PEEP

Synchrony:

Initiation of BreathSize of BreathTermination of Breath

Edi

VT

Health Disease

Neuroventilatory coupling

μV μV μV

ml ml ml

NAVA is not only about triggering Neural Control of Ventilatory Assist (NAVA)

Neu

ro-V

enti

lato

ry C

ou

pli

ng Central Nervous System

↓↓↓↓Phrenic Nerve

↓↓↓↓Diaphragm Excitation

↓↓↓↓Diaphragm Contraction

↓↓↓↓Chest Wall and Lung

Expansion↓↓↓↓

Airway Pressure, Flow and Volume

New

Technology

Ideal

Technology

Current

Technology

Ventilator

Unit

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Edi Catheter

Fr (French) = circumference of the catheter in mm

1. Connection to Edi cable

2. Nutrition feed

3. Evacuation (only 12 and 16 Fr)

4. Reference electrode

5. Electrodes (9)

6. Holes for nutrition/evacuation

7. Inter Electrode Distance (IED)

8. Lumen for electrodes

9. Sump lumen (only 12 and 16 Fr)

10. Feeding lumen

11. Barium strip for X-ray identification

12. Coating for easier insertion and better

electrical conductivity (indicated in the

picture with light blue)

13. Scale in centimeters from the tip

Edi catheter preparation

Ventilator set-up Catheter positioning

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Catheter positioning 2 NAVA ventilation tuning

NAVA ventilation tuning

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How does it work in real life? Status quo in the literature• 235 peer reviewed manuscripts

• Latest systematic review: Beck J, et al.

Minnerva Anestesiologica 2016; 82(8):874

• Clinical studies on newbrons:

– Invasive NAVA: 6 studies (n=106 baies);

GA=24weeks, bw=728g

– Non-invasive NAVA: 2 studies (n=17 babies);

GA=24 weeks, bw=812g

• Results:

– Limits PIP and TV

– Superior patient-ventilator interaction

Electrode Array in Neurally Adjusted Ventilatory

Assist (NAVA)

Sinderby et al, Nature Medicine 1999; 5(12):1433-1436

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Mechanical ventilation induces

prolonged neural expiratory time

• 14 patients with ARDS

• Draeger Babylog 8000– Trigger setting @1

– Flow 10 L/min

• Eadi measured with esophageal electrodes

• CONCLUSIONS:– No reflex deactivation of the diaphragm during SIMV

– 53% infant-ventilator asynchrony of the total breath

– Asynchrony associated predominantly with expiratory asynchrony

– Online monitoring of diaphragm activation during IMV

Beck, J., et al., Pediatr Res, 2004. 55(5): p. 747-754.

Mechanical ventilation induces

prolonged neural expiratory time


NAVA improves synchrony and

respiratory unloading

• 12 New Zealand rabbits

– (ARDS lung lavage model)

– Servo I (VT=6 mL/kg, RR=20, FiO2=0.5, PEEP=2 cmH2O)

– Incremental PSV and NAVA run for each animal

• CONCLUSIONS:

– NAVA requires small increase in airway pressure to unload the

diaphragm

– NAVA interferes less with natural breathing pattern than PSV

Beck, J., et al., Pediatr Res, 2007. 61(3): p. 289-294. Beck, J., et al., Pediatr Res, 2007. 61(3): p. 289-294.

NAVA improves synchrony and respiratory unloading

NAVA lo NAVA hi PSV lo PSV hi

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NAVA in LBW infants

• 7 premature infants < 36 weeks ga– 5F oro-gastric tube

– Conventional ventilation group: Babylog Draeger, PSV

– NAVA group: Servo300 with NAVA:• Intubated – ET tube, NAVA matched PIP

• Non-intubated – SNP tube, NAVA adjusted to reach this same delta IP

• CONCLUSIONS:– Patient-ventilator synchrony not affected by the presence

of leak

– Interface with less leak would increase the efficiency of non-invasive ventilation with NAVA


NAVA in LBW infants


PSV+VG NAVANIV NAVA

NAVA NIV NAVA

PSV+VGPSV

Synchrony is not affected by leaks

during non-invasive ventilation


Patient-ventilator synchrony in children

Beck J, et al. Minnerva Anestesiologica 2016; 82(8):874

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Edi Catheter positioning procedure

Edi Catheter positioning window

• Four ECG waveforms

for Edi catheter

position

• Edi waveform

• Scale and sweep

speed settings

• Freeze function

• Numerical values of

Edi peak and Edi min

Fine-tune the settings in Pressure Support

Trigger Edi

• Trigger Edi zawsze na 0.5 uV

NAVA estimation

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NAVA titration

• Starting at NAVA=0.5 => every 3 minutes increases

until NAVA=4

Edi from 1 premie Edi from all premies

Firestone KS, et al. J Perinatol 2015;35:612e6.

Edi Peak and Minimum

Neonates > 37 weeks with no active respiratory problems and feeding

normally

**

* P < 0.05

Stein ,Wilmoth and Burton 2010

Beck J, et al. Minnerva Anestesiologica 2016; 82(8):874

NAVA optimization

• Optimize the NAVA level according to Edi max, which

should be targeted between 5-15 μV.

- If Edi max is < 5 μV, decrease the NAVA level.

- If Edi max is > 15 μV, increase the NAVA level.

• The changes in NAVA level should be 0.1-0.2 cmH2O/μV

at a time. The changes in NAVA level are mediated in a

few breaths to Edi max. The usual NAVA level is 0.5 – 2.0

cmH2O/μV.

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Setting up PEEP

• Initially, set the same PEEP as in the previous

ventilator settings. If Edi min is constantly > 1

μV (as a sign of tonic diaphragmatic activity to

maintain FRC), increase PEEP.

Setting up apnea time

• Set the initial apnea time at 5 seconds. If

breathing is irregular and the patient unstable,

you may decrease apnea time down to 2

seconds. This will result in backup breaths after

each 2-second apnea until next spontaneous

breath indicated by Edi signal occurs. However,

make sure that the backup ventilation does not

hyperventilate the patient preventing

spontaneous breathing efforts (which would

keep the patient unnecessarily on backup

ventilation).

Back-up settings

• A shorter apnea time (<5 seconds ) increases

the significance of backup ventilation, as there

is a risk for hyperventilation. This does not

usally occur with NAVA ventilation.

• Adjust the backup settings appropriately

taking into account the pre-NAVA settings and

the recovery process of the patient.

Weaning patients from NAVA

• Decrease the NAVA level as the patient’s

pulmonary status improves. Usually, the

patient is ready to be extubated when the

NAVA level is ≤ 0.5 cmH2O/μV.

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NIV NAVA in practice

• The NAVA levels in NIV NAVA are usually lower

than in invasive NAVA (0.5 – 1.0 μV/cmH2O).

Higher NAVA levels may increase the amount of

gas entering the stomach/intestine and cause

abdominal distention.

- If Edi max is < 5 μV, decrease the NAVA level.

- If Edi max is > 20 μV, increase the NAVA level.

• The changes in NAVA level should be 0.1-0.2

μV/cmH2O at a time. Usually, patient can be

switched to nCPAP, when the NAVA level is < 0.5

cmH2O/μV.

NIV NAVA

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NIV NAVA

NIV NAVA

NIV CPAP

When using nCPAP NAVA set-up NAVA=0

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2d of life, 750g, 1 dose of SurvantaPIP decreases when on NAVA

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32 weeks, 2140 gm, CLD , NAVA 533 weeks, 2260 gm, RDS , NAVA 2.5

30 weeks, 1150 gm, RDS and

pneumothorax, NAVA 2

3 month old ex 28 week infant with

pulmonary hypoplasia, NAVA 2

Dynamic Compliance improves on

NAVA

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**

Neonates with Acidosis - on

SIMV/PC and then on NAVA

7,05

7,1

7,15

7,2

7,25

7,3

7,35

7,4

7,45

SIMV/PC NAVA

pH < 7.38

7.29

35

45

55

65

75

85

pCO2 > 45SIMV/PC NAVA

7.32

P = 0.018

P = 0.0008

55.9

49.5

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Neonates with Alkalosis - on

SIMV/PC and then on NAVA

7,3

7,35

7,4

7,45

7,5

7,55

SIMV/PC NAVA

pH > 7.42

10

20

30

40

50

SIMV/PC NAVA

pCO2 < 35

7.47

7.39

P = 0.004

34.5

29.9

P = 0.05

Neonates with normal pH and pCO2

- on SIMV/PC and then on NAVA

20

30

40

50

60

SIMV/PC NAVA

pCO2 35 - 45

7,3

7,35

7,4

7,45

7,5

SIMV/PC NAVA

pH 7.38 - 7.42

7.39

7.38

39.5 40.8

P = 0.82P = 0.45

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NAVA 2.2

NAVA allows neonates to wean

their own PIP over time

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NAVA 2 NAVA 3.2

Improved Compliance over time on NAVA

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Diaphragm activity

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Summary

• Neonates appear to have intact neuro-ventilatory coupling with functional feedback pathways.

• Patient selection is important – not all neonates are candidates for NAVA and, some may not be candidates all the time (sedation, PPHN, IVH, CNS)

• Many neonates ventilate on NAVA with lower PIP (TV) and FiO2 then on conventional ventilation.

Summary

• Many neonates improve their blood gases on NAVA despite ventilating with lower pressures.

• Many neonates decrease their own PIP (TV) over time while on NAVA – “auto weaning”

• Many neonates have improved compliance on NAVA.

• In this small number of patients no significant complications or side effects were noted while on NAVA.

• Large multi-center trials are needed to answer questions if: – NAVA decreases time on ventilators?

– NAVA decreases the incidence of chronic lung disease?

– Is it helpful for MIST/INSURE?

But does it make a difference to outcomes?

NAVA WORKS IN

NEONATES!Thank you

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