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

DENVER, CO

Background

Before deciding on a mode…

• Type of respiratory failure/indications for ventilation

• Goals of ventilation

• Available resources

• Where is the data!

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

• Management of increased

cranial pressure

Classification of Respiratory Failure

Goals of ventilation

◦ Assist for neural or muscle dysfunction

◦ Correct respiratory acidosis

◦ match metabolic demand

◦ Rest respiratory muscles

◦ Optimize V/Q

◦ Optimize P/V relation

◦ Optimize WOBventvs WOBpatient

• Liberate as soon as possible

◦ Optimize weaning

History of ventilation

Dr P K Dash, Trivandrum

Introduction of modes

Dr P K Dash, Trivandrum

APRV Airway pressure release ventilation

ASB Assisted spontaneous breathing

ASVassisted spontaneous ventilation

ASV Adaptive support ventilation

ASV assisted spontaneous ventilation

ATC Automatic tube compensation

Automode Automode

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 ventilation and 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 Ventilation or 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 VCMV (V-CMV) Volume controlled mandatory ventilation VCV Volume controlled ventilation or VCVS Volume Support

MODES….

Murray and Nadal, Textbook Resp Med

◦ Targeting scheme (settings)

◦ Vt, inspiratory time, frequency, FiO2, PEEP, flow trigger

Basic modes

Traditional VT Low VT Mortality 39.8% 31%

p=0.007

Supine Prone Mortality 41% 23.6%

p=<0.001

ARSnet NEJM 2000; 342: 1301-1308 Guerin et al NEJM 2013; 368: 2159-2168

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)

Papazian et al NEJM 2010; 363: 1107-1116

APRV

Open Lung Ventilation

CPAP

APRV

HFOV

Elevate MAP

• Achieves VT (delta P) by periodic release of pre-chosen higher CPAP value to a lower CPAP level

• Spontaneous breathing is unrestricted at

both levels

• If no spontaneous breaths, same as PCIRV

Stawicki SP J Intensive Care Med 2009; 24: 215

Frawley ACCN Clinical Issues 2001;12:234

Setting P and T High

Setting T Low and P Low

• These are interdependent depending on

method used for release

◦ Method 1: P Low set at 0 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 0 cm H2O, T low 0.2 to 0.8

sec

Guidelines – Crit Care Med 2005: Vol 33, No 3 – S228 – S240

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

• Decrease in need for sedation/paralytics

Benefits of APRV - Spontaneous

Breathing (SB)

CO, ↓ BP and ↓ organ perfusion SB negates many of these ill effects

◦ Kuhlen 2002, Hedenstierna, 2006

diaphragm, which is associated with ↓ atelectasis and improved V/Q matching

◦ Putensen 1999, Neumann 2005, Wrigge 2005

associated with less use of sedation and muscle

relaxation

◦ Putensen 2001, Kaplan 2001

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)

• Hemodynamic instability

Adjusting Ventilator in APRV

APRV Weaning

• Increase T High (12-15 sec) and decrease P High (<16cm H2O) until patient is weaned to CPAP with ATC then wean CPAP to

extubation

• May also transition to conventional

ventilation once FIO2 is <.5 and wean per

protocol

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

Putenson AJRCCM 2001;164:43

• No benefit over lung protective ventilation in small RTC in trauma population

• Trend towards increased vent days, ICU

LOS and VAP

• Need comparative study

Maxwell at al, J Trauma 2010; 69: 501

Proportional Modes

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 output is keyed to neural signal

Ventilator Asynchrony

• Very common in ICU patients

• Associated with increased sedations, longer ICU

stays, longer ventilatory time, increased

incidence of tracheostomy and mortality

Diaphragm need to work or else

Diaphragm biopsies on vented patients show:

• Decreased size of slow and fast twitch fibers

• Increased markers of proteolysis

PROPORTIONAL ASSIST VENTILATION

Proportional Assist Amplifies Muscular Effort

Muscular effort (Pmus) and airway pressure assistance (Paw) are better matched for Proportional Assist (PAV) than for Pressure Support (PSV).

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

PMUS + PVENT =(flow x resistance)+(volume÷compliance)

Proportional Assist Ventilation

• Need a breathing patient

• Improves patient – ventilator synchrony

• Does not improve ventilation/oxygenation – no control of ventilatory pattern!

• May prevent lung injury, not shown to improve weaning!

NEURALLY ADJUSTED VENTILATORY ASSIST VENTILATION

• 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

• Trigger free from any lung interference

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

Pneumatic Triggering Modes

Flow and Pressure

Patient - Ventilator Interaction

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

Traditional Spontaneous Breaths Nava Stimulated Breaths

NAVA Provides Flexible Response to Effort

Volume

PAW

DGMEMG

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

Components

• 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

• Lumen for gastric feeding

Signal capture

• All muscles (including the diaphragm

and other respiratory muscles) generate electrical activity to excite muscle

contraction.

• The Edi is captured by an esophageal catheter with an attached electrode array The signal is filtered and provides the input for control of the respiratory assist delivered by the ventilator.

Catheter verification

As first electrode on catheter goes from above to below the diaphragm, the QRS dampens and P disappears

The waveform turns blue when

an Edi signal is captured You want the middle two waveforms

to capture the Edi.

• NAVA level - set to a target pressure support Default 1 cmH2O/uV

• Trigger - default 0.1 to 2.0 uV

• Improves patient-vent synchrony

• Adapts to changes in demand and consistently

unloads diaphragm

• Can do 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…

als/E-learning-mechanical-ventilation/

• NAVA decreased asynchrony and use of extubation NIV

post-• No difference in vent free days or mortality

Demoule et al Int Care Med 2016; 42: 1723

• 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

Kataoka et al Ann Int Care 2018; 8: 123

• 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

expensive equipment

Thank you!