Why Intubate and Ventilate ?

1. Improve Oxygenation (PaO2, SaO2).2. Improve ventilation (PaCO2).3. Relieve work of breathing.4. Unload Respiratory Muscle.

Evaluate before you sedate

The sooner the better!!!

How soon do you allow your patient to breath

spontaneously?

Does your ventilated patient appear to be struggling or uncomfortable ?

Lesson Learned!!

Conventional modes of

ventilation can not cope well with the ever-

changing patients

Ventilatory needs

The Next Generation of Synchronization Ventilatory Support

PAV+Prevent Asynchrony with

Ventilator

Ventilator Support is proportional to:Instantaneous Effort (Pmus)Pulmonary Mechanics (Resistance, Compliance)

How Does PAV+ Work?

Equation Of Motion=Pmus + Paw = (Flow x R) + (Volume x E)

PAV+ measures patient demand by monitoring flow and volume every 5 milliseconds and measures compliance and resistance every 4 to 10 breathes

Patient effort

throughout inspiration

{

Inspiratory Effort

VLUNG

PLUNG

RLUNG

CLUNG

RET

Trigger and Execute PAV

ViI

.

Pappl Ventilator

Pi E

T +

PA

TIE

NT

Pi L

UN

G-T

HO

RA

X

Sum: PiFLOW +

PiVOLUME = Pi

Y

S (ViL EL)

S (ViY * Ri

SYS)·

ViY

.

ò ViY dt =

ViL

·

PiY=S (Vi

L * RiETT)+ S (Vi

L RL) + S (ViL

Ers)

. .

Response to patient’s inspiratory effort “Mirror Image Breath

Response to patient’s inspiratory effort “Mirror Image Breath

Muscle Effort Amplifier

Results of pressure strategy with greater patient effort (PSV vs.

PAV+)

PAV+ and

Patient Control

Inspiration

How deeply to

breath?

When the breath

ends?

(A)

Patient determines when inspiration begins when Flow senses at the Wye

(B)

The ventilator will continue to provide the gas as long as the patient inspiratory effort is continuing

(C)

Because pressure is proportional to pt inspiratory effort , when effort ends pressure rapidly declines and flow stops

So How Does It Work ?

Q. How does the clinician know where to set the %Support?

1. Sound Clinical Assessment.

2. Work of Breathing (WOB) bar.

Clinical Assessment

Vital Signs ABG

Signs of Respiratory Distress:Respiratory rate > 40 breaths/minute PLUS… Marked use of accessory muscles Diaphoresis Abdominal paradox Marked complaint of dyspnea Etc…

PAV+, Understanding the WOB Bar

Proportional Assist Ventilation (PAV+),

Chasing Liberty

Literature Review

Ventilator

Pressure

Patient Effort

VC

VCV

Trigger Only

Trigger Only

Active Effortbc

Active Effort

cb

Vol

ume L

UN

G

Flo

ww

ye

Pre

ssur

e wye

Time

Time

Time

bc

Pressure Limited Ventilation (PCV, PS)

Ventilator

Pressure

Patient Effort

VC

PCV/PS

More physiologicalPAV+

Proportional assist Ventialtion and Neurally Adjusted Ventilator Assist Robert Kacmarek PhD Resp Care Feb. 2011 Vol. 56 No. 2

Physiological Mode

Levine et al., Rapid Disuse Atrophy of Diaphragm Fibers in Mechanically Ventilated Humans, NEJM 2008 358: 1327-1335

MV and Diaphragm

Complete controlled ventilation beyond 24 hours may cause Respiratory Muscle Injury and can result in:

Ventilator Induced Diaphragmatic Dysfunction

Sassoon et al (2002). Altered Diaphragm Contractile Properties with Controlled Mechanical Ventilation. J Appl Physiol 92(6): 2585-2595

Length of ICU Stay

Frequent setting changes and

increase sedation

requirements

Increase Ventilation time , possible Muscle

Atrophy and Increase Length of

stay

Asynchrony

> 25% of patients on VC and PSV had higher incidence of Asynchrony. Asynchrony Index (AI) of > 10% of respiratory efforts. Higher incidence of Asynchrony is associated with prolonged duration of MV (25 vs. 7 days, p=.005).More likely to receive Tracheostomy (33% vs 4%)

Thille et al .(2006) Intensive Care Med 32; 1515-22

PVA is common in Conventional Mode of Ventilation

Failure to Synchronize

Deleterious Effects of PVA:• Patient Fights Ventilator• Higher Work of Breathing• More Sedation Required• Muscle Fatigue• Dynamic Hyperinflation• Delayed or prolonged weaning• Longer ICU Stay• Higher Costs.

Respir Care (2005).50(2); 202-234

Potential Clinical Advantages

•The patient ‘drives’ the ventilator •Avoids ventilator over-assistance

•Less patient-ventilator asynchrony –Asynchrony associated with

•More sedation (deWit, M. Journal of Critical Care

2009:24;74-80) •Longer duration of mechanical

ventilation(Thille, A. Intensive Care Medicine 2006;

deWit, M. Crit Care Med 2009) •Disrupted sleep

(Bosma, K, Crit Care Med 2007, Fanfulla, F AJRCCM 2005)

PAV+ Increases patient safety by decreasing the risk of over-assisted

ventilation less likelihood of overventilation — With PAV+ software,

there is no minimal delivered tidal volume like with other modes. If the % Support dialed in is more than is necessary, patients will down regulate their efforts. Because with PAV+, the pressure delivered is a function of effort. When effort decreases the pressure demand will also decrease. Accordingly, this feedback mitigates the tendency for overventilation. By contrast, with other modes the ventilator will continue to give the same pressure or volume regardless of what happens to effort, so long as the effort is enough to trigger.

Also, in the case of airway artifacts like hiccups or heartbeats, no standard volume or pressure would be accidentally delivered because with PAV+, the ventilator would stop delivering gas as soon as the artifact was over. With other modes, cardiac artifacts may continue to cause frequent triggering and delivery of large volumes even when efforts cease completely.

Imanaka H. Crit Care Med. 2000;28(2):402-407.

PAV+ Increases patient safety by decreasing the risk of over-assisted

ventilation Preservation and enhancement of the patient’s

control mechanisms — With PAV+ the breath is being driven by the patient’s own control center and reflexes. One such reflex is the Hering-Breuer reflex, which causes the inhibition of inspiratory efforts when tidal volume reaches a physiologically determined threshold, thus preventing over distension of the lung. Because the ventilator ceases its pressure when inspiratory effort is terminated, stimulation of this reflex would cause the breath to cycle off.

Improved hemodynamics — Research has shown that when patients were switched from Volume Control to manual PAV+, cardiac output increased by 22% in septic patients. Patrick W, et al.. Am J Respir Crit Care Med.

1993;147:A61

PAV+ Increases patient safety by decreasing the risk of over-assisted

ventilation Weaning — The greater the reliability of ventilator rate as a measure of distress, the better the decision-making on tolerance. Because with PAV+ there are little or no ineffective efforts, ventilator rate and patient rate are the same. So, when ventilator rate increases as the assist level is reduced (e.g., during a weaning trial), it means that the patient’s rate has also increased, a sign that suggests this new level is not tolerated (distress).

With other modes in which ineffective efforts may exist (e.g., PSV, volume - cycled), ventilator rate can be considerably less than the patient’s rate. Giannouli E. Am J Respir Crit Care Med.

1999;159(6):1716-25 .Thille AW,. Intensive Care Med. 2006;32(10):1515-1522 .

Leung P. Am J Respir Crit Care Med. 1997;155(6):1940-1948 .

PAV+ Increases patient safety by decreasing the risk of over-assisted

ventilation Because the number of ineffective efforts decreases, often dramatically, as assist level is decreased, the ventilator rate frequently jumps during a weaning trial despite the fact that patient’s rate has not changed.

This can lead to the false diagnosis of weaning failure.

The PAV+ may emerge as a useful tool in weaning because with PAV+ there is less likelihood of misinterpretation of actual respiratory rate. In addition, this type of ineffective muscle contraction has been associated with muscle injury.

With PAV+, this is less likely to occur. Giannouli E. Am J Respir Crit Care Med. 1999;159(6):1716-25 .

Van Der Meulen JH,. J Appl Physiol. 1997;83(3):817-823 .Devor ST. J Appl Physiol. 1999;87(2):750-756 .

PAV+ Increases patient safety by decreasing the risk of over-assisted

ventilation Less-invasive technology.

Unlike other approaches to measuring patient demand (e.g., esophageal manometry or diaphragm EMG), there is no need for an additional invasive procedure, which could lead to complication from incorrect placement.

Cost and time are other obvious advantages to a less invasive approach.

The PAV+ takes random measurements of compliance and resistance along with rapid samples of pressure and flow to determine the support pressure via a cuffed artificial airway.

What Kind of Patient Would Benefit more from PAV?+

1. Comfort.2. Lower peak airway pressure.3. Less need for paralysis and/or

sedation.4. Less likelihood for over ventilation.5. Preservation and enhancement of

patient’s own control mechanisms such as metabolic ABG control and Hering-Breuer reflex.

6. Improved efficiency of negative pressure ventilation. M Younes. Am Rev Respir Dis

1992;145:114- 120.

12 COPD patientsUsing VASBreathing comfort was sig. with PAV

(38 vs. 11)

Wysocki et al .(2002) Crit Care Med. 30(2); 323-329

Comfort

Wrigge et al .(1999) Intensive Care Med. 25; 790-798

• 13 Ventilated COPD patients

• PAV vs. PSV

Vt Variability

Kondili et al .(2006) Intensive Care Med. 32; 692-699

WOB

Bosma et al .(2007) Crit Care Med. 35(4); 1048-1054

PVA

Settings Manipulation and Need for Sedation

Compared with PSV, PAV was associated with:

Fewer manipulations of ventilator settingsFewer changes in sedative dosing.

Careful evaluation of the patient prior to sedation may help

reduce the use of unnecessary sedation.

Siegel MD. Clin Chest Med 2003; 24 (4):713-725

Evaluate before Sedate

Probability to remain on Spontaneous Mode

RCT of 208 critically ill patients on a controlled mode randomized to either PAV or PSV.

Probability to remain on Spontaneous Mode

Failure to transition: PAV 11%, PSV 22%.Proportion of patients who developed to asynchrony: PAV 5.6%, PSV 29%.

Probability to remain on Spontaneous Mode

Proportional assist Ventialtion and Neurally Adjusted Ventilator Assist

Robert Kacmarek PhD Resp Care Feb. 2011 Vol. 56 No. 2

Background 6% of ventilated patients are prolonged

mechanically ventilated (PMV)

20% to 30% are difficult-to-wean.

Weaning tends to be delayed-Exposing the patient to unnecessary discomfort

-Increased risk of complications-Increasing the cost of care and mortality 12% vs 27% .

Time spent in the weaning process → 40–50% of the total duration of mechanical ventilation.

Intensive Care Med (2013) 39:1885–1895

DOI 10.1007/s00134-013-3014-9

Reasons contributing to weaning failure in anesthetized and critically

ill patients

Objective:

This study was designed to determine the effect of PAV+ on adult difficult-to-wean PMV patients.

Gulf Thoracic Congress March 13, 2014

Results:

13 adult Pts were included in this study. 9 of the Pts with Mean duration of MV was 53.2 days prior to PAV+ trial. On PAV+, NIF and P 0.1 measurements improved by 87% and 79% respectively from the baseline. They were successfully weaned off MV with an average weaning time of 5.8 days. 4 of the Pts were unsuccessfully weaned off MV and retained back to SIMV mode and went to be prolonged ventilator dependents.

Gulf Thoracic Congress March 13, 2014

NIF and P 0.1 measurements throughout PAV+ trails Time Spent on Conventional Weaning and PAV+

Gulf Thoracic Congress March 13, 2014

Conclusion:

PAV+ can be used safely and efficiently to wean adult difficult-to-wean PMV patients who failed multiple trails of conventional weaning. PAV+ provides opportunity for a respiratory muscle to recover and strengthen, increasing the likelihood of weaning success.

Gulf Thoracic Congress March 13, 2014

PAV vs PSV in the weaning of Pt with AECOPD

60 Pts: 30 on PAV, 30 on PSVWeaning Success PAV vs PSV 90% vs 66.7%In PAV,

less PVA 1.5 days reduction in mean days of MV2 days reduction in mean days of ICU stay1.8 days reduction in mean days of hospital stay

New Developments in PAV+

Younes M, et al. Intensive Care Med 2007; 33: 1337–1346

Kondili E, et al. Intensive Care Med 2010; 36: 648–655 .

• Recently, a new technology has been introduced that aims to monitor and improve patient– ventilator interaction.

• With PVI monitor, a signal representing an estimate of the patient’s total respiratory muscle pressure (Pmus,PVI) is calculated via the equation of motion, utilizing estimated values of resistance and elastance of the respiratory system, obtained noninvasively.

• The waveform of Pmus.PVI is continuously displayed

online on a breath-by-breath basis and can be used to trigger the ventilator. It has been shown that this triggering method may substantially shorten the triggering delay (by approximately 70%), even in patients with dynamic hyperinflation.

• Theoretically, this system should increase the efficiency of PAV+ to support critically ill patients with dynamic hyperinflation.

Why PAV+ is not Commonly Used?

PAV (1992) PAV+ (2005)

PAV+ (2005) is more accurate, safe & effective.

Failure to Knowledge Transfer??? *

Application sometimes regarded as difficult**

PAV+ had not been investigated thoroughly in weaning trails** .

**Boles, al et, Eur Respir J 2007; 29: 1033–1056

Why PAV+ is not Commonly Used?

Conclusion

PAV+– Provides assistance in PROPORTION to patient effort– Provides patient greater control of modulating VE– Reduces patient-ventilator asynchrony– Improves sleep quality for patients asynchronous on

PSV

PAV+ may help:– Preserve Respiratory Muscle Strength– Facilitate Weaning– Decrease Need for Sedation

Does all this mean extra coffee breaks for clinicians?

PAV is safe and effective mode of ventilation.There is strong evidence that PAV provides some advantages related to patient comfort and better synchrony.PAV may be helpful with difficult to wean patients (muscle fatigues, changing lung mechanics)Understanding PAV physiology and operation is essential for save use of the mode.

Conclusion

Questions Need to be Answered?

Non-invasive PAV+?PAV+ as Initial Setting Mode for Non-Fully Sedated or Paralyzed Patient?PAV+ in The Specialized Weaning Units?PAV+ in The Home Ventilators?