Peter C. Rimensberger, MD

Professor of Pediatrics and Intensive Care Medicine

Pediatric and Neonatal Intensive Care

University Hospital of Geneva

Switzerland

Neurally adjusted ventilatory assist (NAVA):

It’s place in the PICU

bv

Peter C. Rimensberger, MD

Professor of Pediatrics and Intensive Care Medicine

Pediatric and Neonatal Intensive Care

University Hospital of Geneva

Switzerland

Neurally adjusted ventilatory assist (NAVA):

It’s place in the PICU

No COI to declare, but we use NAVA in our unit

Mechanical Ventilation

EquipmentPatient

Decision taking

controls the

machine

Assisting spontaneous breathing in an ideal world

→ fully synchronized

→proportional to the patient effort

→adapted to the condition of the respiratory system

In an ideal world assisted ventilation should be:

Steven M. Donn and Sunil K. Sinha in:

Pediatric and Neonatal Mechanical Ventilation (ed. Rimensberger) 2015

What information does the ventilator need?

- from the operator

- from the patient

Pressure–time curve

and types of patient–ventilator

asynchronies

1) Triggering asynchrony

2) Flow asynchrony

3) Cycling asynchrony

Donoso A et al. Bol Med Hosp Infant Mex. 2016;73(3):149-165

Asynchronies during mechanical ventilation

are associated with mortality

Blanch L et al. Intensive Care Med 2015 (online) DOI 10.1007/s00134-015-3692-6

Asynchrony index % = (n events/total RR) x 100

→ Ventilation modes that halp to reduce patient-ventilator

asynchrony should be promising for improving outcome

Tiggering and breath cycling

Neurally Adjusted Ventilatory Assist (NAVA)

=improved synchronized assist

NAVA:

Diaphragm electrical activation

Sinderby, Nature Med 1999

Classical:

Flow or pressure signal

Syn

ch

ron

iza

tio

n

Improving synchronization, does it improve outcome?

Improving synchronization, does it work?

Major types of asynchrony events

Auto-triggering Ineffective efforts Double-triggering

Late cycling Premature cycling

1) trigger failure

2) delayed triggering

3) auto triggering

4) premature cycling off

5) late cycling off1 1 1 1 1

22 / 5 2 or 3 55

Chaos

→ Discomfort and Stress

→ More Sedation

→ Prolonged Ventilation

Patient-Ventilator Asynchrony during Mechanical

Invasive Assisted Ventilation in Children:

Type of Asynchrony Events

Vignaux L et al. PCCM 2013

Asynchrony index % = (n events/total RR) x 100

Subject–ventilator synchrony during neural

versus pneumatically triggered non-invasive

helmet ventilation

% of Asynchrony Comfort

Moerer O Intensive Care Med (2008) 34:1615–1623

Delisle S et al. Annals of Intebsive Care 2011,1:424

Sleep quality is improved with better

patient-ventilator synchronization

Sedation Level Inspiratory Pressures

Oxygenation Ventilation efficiency

Kallio M et al.

Pediatr

Pulmonol.

2015;50:55–62

Intention to

treat

analysis:

85 vs. 85

per

protocol

analysis:

80 vs. 81

Kallio M et al. Pediatr Pulmonol. 2015;50:55–62

Limitations: All pediatric patients expected to need invasive ventilation for

at least 30 min were eligible for his trial, but critically ill patients with a

severe respiratory, hemodynamic or bleeding disorder, and patients

needing high frequency oscillatory ventilation (HFOV) were excluded.

P = 0.07 P = 0.03

Neurally Adjusted Ventilatory Assist (NAVA)

= synchronized proportional assist

Sinderby, Nature Med 1999

Pro

po

tio

na

l A

ss

ist

Tiggering and breath cycling

NAVA:

Diaphragm electrical activation

Classical:

Flow or pressure signal

Syn

ch

ron

iza

tio

n

Brander L et al. Chest 2009

15 adult, critically ill patients with PaO2/FiO2<300mmHg (ALI)

Tidal volume during NAVA in adults with ALI

with reduced respiratory system compliance

CLdyn under

conventional

ventilation

before being

switched to

NAVA

4.5 – 8.5

ml/kg

Leaks (“bench”)

NIV-NAVA

Sinderby & Beck, Neurally Adjusted Ventilatory Assist in Principles and Practice of Mechanical Ventilation, Third Edition

Editor: Tobin MJ, McGraw-Hill Medical 2013

Patient-Ventilator Asynchrony during Mechanical

Non-Invasive Assisted Ventilation in Children:

Type of Asynchrony Events

Vignaux L et al. PCCM 2013

Asynchrony index % = (n events/total RR) x 100

Seghal IS et al. Intensive Care Med (2016) 42:1813–1815

Asynchrony index in PSV vs NAVA during NIV

NIV-NAVA

Edi

VT

Health Disease

Neuro-muscular coupling

μV μV μV

ml ml ml

66 75 915 Rev. 00

The efficacy of the respiratory muscles does determine the degree of respiratory center output

Perspectives: NAVA for patients with

pathologic neuromuscular coupling

0.5 l

10 %

10 s

PP

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(%)

Vt (l

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(%)

V

t (l)

(%

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Time (s)

EA

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di

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di

Healthy 0.5 l

10 %

10 s

PP

I

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alth

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(%)

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Time (s)

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If the diaphragm becomes

weaker and/or the

inspiratory load increases,

the diaphragm electrical

activation must increase

to maintain a given

volume.

Sinderby et al JAP 1998

Incre

ase

d

insp

ira

tro

y lo

ad

We

ak

dia

ph

rag

me

Piastra M et al. Journal of Critical Care 29 (2014) 312.e1–312.e5

Weaning with NAVA vs. PSV of severe ARDS patients on HFOV

NAVA group: patients form the year 2010

PSV group: patients from the years 2008-2009 matched for age, gas exchange

impairment, and weight.

Results: Ten infants treated with NAVA and 20 with PSV were studied.

1) Heart rate (P < 0.001) and mean arterial pressure (P < 0.001) increased less

during NAVA than during PSV. (better Comfort)

2) PaO2/FIO2 ratio decreased less in NAVA than in PSV (P < 0.001). (better

Oxygenation)

3) With NAVA lower PaCO2 (P < 0.001) and peak pressures (P = 0.001), as well

as higher minute ventilation (P = 0.013). (better Ventilation Efficiency)

4) COMFORT score (P = .004) and duration of support were lower in NAVA than

in PSV (P = .011). (shorter Weaning Time)

Ducharme-Crevier L et al. Critical Care Research Practice 2013, http://dx.doi.org/10.1155/2013/384210

Extubation “failure” or the need for

non-invasive respiratory support

0 cm H2O -10 cm H2O

DPtp = 12 DPtp = 22

The risks of proportional assist ventilation

→ self inflicted lung injury

Very large VT,

excessive DPtp

Small Vt,

moderate DPtp

DPairways

12cm H2O

Vt >> 6 ml/kg

DP12 cm H2OVt 6 ml/kg

moderate inspiratory

effort

-5cm H2O

DPtp = 17

DPairways

12cm H2O

Vt > 6 ml/kg

severe inspiratory

effort

large VT,

high DPtp

Passive patient

1. To assist spontaneous ventilation

→ synchronized assistance

→ proportional assistance

2. To give the patient autonomy (let the patient

“choose te best” settings)

→ but choose wisely your pressure limits

3. To improve patient comfort, reduce sedation

needs and by this facilitate weaning

NAVA: What for?

1. Weaning from mechanical ventilation = handing

over the work of breathing to the patient

2. Reduce imposed work of breathing in various

lung disease patterns (obstructive and restrictive)

3. Reduce imposed work of breathing in neuro-

muscular disease with increased respiratory load

4. Facilitate ventilator triggering and cycling off

→ for patients with severe neuromuscular

weakness

5. NIV-NAVA for patient-ventilator synchronization in

presence of an important leak

NAVA: What are potential indications?