CÁC MODE THỞ MÁY- Joshua Solomon, md

HFFI High frequency flow interruption HFJV High frequency jet ventilation HFOV High frequency oscillatory ventilation HFPPV High frequency positive pressure ventilation.. ILV Independen[r]

Ventilation Modes

JOSHUA SOLOMON, MD

ASSOCIATE PROFESSOR OF MEDICINE

NATIONAL JEWISH HEALTH

Outline

•

Background

•

Basic Ventilation

◦

Low VT

◦

DP

•

APRV

•

PAV

Before deciding on a mode…

•

Type of respiratory failure/indications for

ventilation

•

Goals of ventilation

•

Available resources

Indications for mechanical vent

•

Cardiac or respiratory

arrest

•

Tachypnea or bradypnea

with impending arrest

•

Acute respiratory acidosis

•

Refractory hypoxemia

(PaO2 <60mmHg with FiO2

= 1.0)

•

Inability to protect airway

due to depressed levels of

consciousness.

•

Shock with excessive

respiratory work

•

Inability to clear secretions

with impaired gas

exchange or excessive

respiratory work

•

Neuromuscular disease

with vital capacity < 10-15

mL/kg or NIF < 20 mmHg

Goals of ventilation

•

Do no harm - promote safety

•

Adequate ventilation

◦

Assist for neural or muscle dysfunction

◦

Correct respiratory acidosis

◦

match metabolic demand

◦

Rest respiratory muscles

•

Correct hypoxemia

◦

Optimize V/Q

•

Protect the lung

◦

Optimize P/V relation

•

Promote patient comfort

◦

Optimize WOB

vent

vs WOB

patient

•

Liberate as soon as possible

History of ventilation

Introduction of modes

APRV Airway pressure release ventilation ASB Assisted spontaneous breathing

ASVassisted spontaneous ventilation ASV Adaptive support ventilation ASV assisted spontaneous ventilation

ATC Automatic tube compensation AutomodeAutomode BIPAP Bilevel Positive Airway Pressure CMV Continuous mandatory ventilation CPAP Continuous positive airway pressure CPPV Continuous positive pressure ventilation

EPAP Expiratory positive airway pressure HFV High frequency ventilation

HFFI High frequency flow interruption HFJV High frequency jet ventilation HFOV High frequency oscillatory ventilation HFPPV High frequency positive pressure ventilation

ILV Independent lung ventilation IPAP Inspiratory positive airway pressure IPPV Intermittent positive pressure ventilation

IRV Inversed ratio ventilation

LFPPV Low frequency positive pressure ventilation MMV Mandatory minute volume

NAVA Neurally Adjusted Ventilatory Assist NIF Negative inspiratory

NIV Non-invasive ventilation PAP Positive airway pressure

PAV and PAV+ Proportional assist ventilationand proportional assist ventilation plus PCMV (P-CMV) Pressure controlled mandatory ventilation

PCV Pressure controlled ventilation or PC Pressure control

PEEP Positive end-expiratory pressure PNPV Positive negative pressure ventilation

PPS Proportional pressure support

PRVC Pressure regulated volume controlled ventilation PSV Pressure Support Ventilationor PS

(S) IMV (Synchronized) intermittent mandatory ventilation S-CPPV Synchronized continuous positive pressure ventilation S-IPPV Synchronized intermittent positive pressure ventilation

TNI Therapy with nasal insufflation

What is a Mode?

•

3 components

◦

Control variable

◦

Pressure or volume

◦

Breath sequence

◦

Continuous mandatory

◦

Intermittent mandatory

◦

Continuous spontaneous

◦

Targeting scheme (settings)

Traditional VT Low VT

Mortality

39.8%

31%

p=0.007

Supine

Prone

Mortality

41%

23.6%

p=<0.001

HR for death at 90 days for those

on cisatracurium = 0.68

(CI 0.48 - 0.98, p=0.04)

Amato et al NEJM 2016; 372: 747-755

One standard deviation increase in

△

P (7cm H2O)

increases mortality

by 40%

(p < 0.001)

Open Lung Ventilation

CPAP

APRV

HFOV

APRV

•

Achieves V

T

(delta P) by periodic release of

pre-chosen higher CPAP value to a lower

CPAP level

•

Spontaneous breathing is unrestricted at

both levels

Terminology

Setting P and T High

•

P High - either:

◦

the desired plateau pressure (typically 20-30 cm

H2O), if newly committed

◦

the previous plateau pressure, if transitioning from

VCV or PCV

◦

2-4 cm H2O above the mean airway pressure, if

transitioning from HFOV

•

T High

◦

The inspiratory time (Thigh) set at a minimum of

4.0 seconds

Setting T Low and P Low

•

These are interdependent depending on

method used for release

◦

Method 1: P Low set at and T low set at 50-75%

expiratory flow (creating iPEEP)

◦

Method 2: P Low is set at “Best –PEEP” and T Low

set to just allow full exhalation

*Example = P low cm H2O, T low 0.2 to 0.8

sec

Benefits of APRV

•

Utilizes an “open lung” approach

•

Minimizes alveolar over-distension

(volutrauma) and peak airway pressures

•

Avoids repeated alveolar collapse and

reexpansion (atelectrauma) – improves

aeration at lung base

•

Allows spontaneous ventilation

Benefits of APRV - Spontaneous

Breathing (SB)

•

PPV causes↑ intra-thoracic pressure, ↓ venous return, ↓

CO, ↓ BP and ↓ organ perfusion SB negates many of

these ill effects

◦

Kuhlen 2002, Hedenstierna, 2006

•

SB results in a more pronounced excursion of the

diaphragm, which is associated with ↓ atelectasis and

improved V/Q matching

◦

Putensen 1999, Neumann 2005, Wrigge 2005

•

SB, and modes of ventilation that incorporate it, are

associated with less use of sedation and muscle

relaxation

Detriments/Contraindications to

APRV

•

Untreated increased intracranial pressure

(concern with high MAP, hypercapnea and

decreased venous return)

•

Large untreated bronchopleural fistula

•

Obstructive airways disease (concern with short

release time and potential for worsening

auto-PEEP)

Adjusting Ventilator in APRV

•

Alkalemia

◦

Increase T High

◦

Reduce P High (especially if V

T

too high and

oxygenation adequate)

◦

Assess if high rate of SB

•

Acidemia:

◦

Decrease T High

◦

Assess T Low for sufficient length

APRV Weaning

•

Increase T High (12-15 sec) and decrease P

High (<16cm H

2

O) until patient is weaned to

CPAP with ATC then wean CPAP to

extubation

•

May also transition to conventional

ventilation once FIO

2

is <.5 and wean per

Evidence: APRV vs PCV

•

RCT; 30 trauma ARDS pts

•

PEEP = LIP +2; PIP<UIP; VT~7 mL/kg

•

T-

high

& T-

low

adjusted so flow returns to zero

•

APRV encouraged spont breathing; PCV

paralyzed x72 hrs

•

APRV resulted in:

◦

Shorter duration of ventilation (15 vs 21 days)

◦

Shorter ICU stay (23 vs 30 days)

◦

Less need for sedation

◦

Improved gas exchange

However….

•

No benefit over lung protective ventilation in

small RTC in trauma population

•

Trend towards increased vent days, ICU

LOS and VAP

•

Need comparative study

Modes That Vary Their Output to Maintain

Appropriate Physiology (Proportional Modes)

•

Proportional Assist Ventilation (Proportional

Pressure Support)

◦

Support pressure parallels patient effort

•

Adaptive Support Ventilation

◦

Adjusts Pinsp and PC-

SIMV rate to meet “optimum” breathing

pattern target

•

Neurally Adjusted Ventilatory Assist

Ventilator Asynchrony

•

Very common in ICU patients

•

Associated with increased sedations, longer ICU

stays, longer ventilatory time, increased

Diaphragm need to work or else

Diaphragm biopsies on vented patients show:

•

Decreased size of slow and fast twitch fibers

PAV

Proportional Assist Amplifies Muscular Effort

Proportional Assist Ventilation

•

Supports according to the patient's effort, based on

the respiratory flow signal and by adjusting

inspiratory airway pressure in proportion to the

patient's effort during each breath

•

PAV requires accurate, instantaneous measurement

of compliance and resistance

Proportional Assist Ventilation

•

Need a breathing patient

•

Improves patient

–

ventilator synchrony

•

Does not improve ventilation/oxygenation

–

no

control of ventilatory pattern!

•

Meta-analysis of 14 RCTs

•

No evidence of a clinical benefit of PAV

over PS

NAVA

NAVA

•

Controls ventilator output by measuring the

neural traffic to the diaphragm

•

NAVA senses the desired assist using an array of

esophageal EMG electrodes positioned to detect

the diaphragm’s contraction signal (Edi)

•

Flexible response to effort

•

Improves synchrony and weaning

Central Nervous System

Phrenic Nerve

Diaphragmatic Excitation

Diaphragmatic Contraction

Chest wall, lung and esophageal response

Air flow, pressure and volume changes

VENTILATOR

Current technology

Ideal technology

NAVA

Patient - Ventilator Interaction

Beck et al Pediatr Resp Med 2004; 55: 747-54

NAVA Provides Flexible Response to Effort

Volume

P

AW

D

GM

EMG

Catheters

•

Electrode array (10 electrodes) to measure Edi

and esophageal ECG

•

Coating on Edi Catheter for easy insertion

-activate by dipping in water

•

Barium strip for xray identification

•

Disposable

Signal capture

•

All muscles (including the diaphragm

and other respiratory muscles) generate

electrical activity to excite muscle

contraction.

Catheter verification

As first electrode on catheter

goes from above to below the

diaphragm, the QRS dampens

and P disappears

NAVA

•

Improves patient-vent synchrony

•

Adapts to changes in demand and consistently

unloads diaphragm

•

Can post-extubation monitoring

•

No improvements in clinically important outcomes

•

Patient has to be initiating breaths

◦

No heavy sedation, spinal cord injuries etc

•

Need expensive equipment…

•

NAVA decreased asynchrony and use of

post-extubation NIV

•

No difference in vent free days or mortality

•

Found reductions in patients with asynchrony

index >10 % and reductions in weaning failure

and duration of mechanical ventilation in PSV

•

Studies very heterogenous and insufficient

number of studies

Conclusion

•

Newer or more complex modes may not have

benefit over good VC management

•

Consider interventions on the vent that have

been proven to affect outcomes

◦

Low VT, paralysis, proning, ? Driving pressure

•

Newer modes that alter vent parameters based

on demand may improve synchrony and assist in

maintaining diaphragm function

•

Newer modes are limited by the need for

Airway pressure release ventilation assisted spontaneous ventilation Automatic tube compensation Automode BIPAP Bilevel Positive Airway Pressure Continuous mandatory ventilation CPAP Continuous positive airway pressure PPV Continuous positive pressure ventilation PAP Expiratory positive airway pressure FV High frequency ventilation ILV Independent lung ventilation Inspiratory positive airway pressure IRV Inversed ratio ventilation Low frequency positive pressure ventilation Mandatory minute volume Neurally Adjusted Ventilatory Assist Negative inspiratory Non-invasive ventilation PAP Positive airway pressure Proportional assist ventilation proportional assist ventilation plus Pressure controlled mandatory ventilation PC Pressure control P Positive end-expiratory pressure PV Positive negative pressure ventilation Proportional pressure support Pressure regulated volume controlled Pressure Support Ventilation ized) intermittent mandatory ventilation Synchronized continuous positive pressure ventilation Synchronized intermittent positive pressure ventilation I Therapy with nasal insufflation Volume controlled mandatory ventilation Volume controlled ventilation Volume Support •https://www.maquet.com/int/education/profession