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Disclosures  

§  None  

§  No  discussion  of  non  FDA  approved  products  

Background  §  Who are the patients at risk for severe

hypoxemic respiratory failure?

ú  Acute Lung Injury (ALI)    PaO2/FIO2 ≤ 300

ú  Acute Respiratory Distress Syndrome (ARDS)    PaO2/FIO2 ≤ 200

ú  Severe hypoxemic respiratory failure    PaO2/FIO2 ≤ 100

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Background  CT-CHEST of ARDS Patient Problems Encountered:

1.  Volutrauma

•  2o over-stretching or over-distension of normal lung

2.  Atelectrauma •  2o shearing forces as

alveoli open and close

3.  Barotrauma •  2o stiff lungs resulting in

elevated lung pressures

Background  ú  Approximately 16% of deaths in patients with ARDS

results from severe hypoxemic respiratory failure.1

ú  Degree of respiratory failure may be a direct predictor of poor prognosis.2

ú  ARDS patients on lung-protective mechanical ventilation who improve in oxygenation and disease severity in 24h3,4

   13 – 23% mortality

ú  ARDS patients who don’t improve in PaO2/FIO2 ratio in the first 24h of lung-protective ventilation3,4

   53 – 68% mortality 1.  Montgomery AB, et al. Am Rev Respir Dis 1985; 132:485-489 2.  Luhr OR, et al. Am J Respir Crit Care Med 1999; 159:1849-186 3.  Villar J, et al. Intensive Care Med. 1999; 25 (9): 930-935 4.  Ferguson ND, et al. Intensive Care Med. 2004; 30 (6): 1111-1116

§  Rationale ú  The accumulating body of evidence suggests that

volutrauma and barotrauma contribute to the development and worsening of ALI and ARDS.

Background  

1 2 3

1.  Normal Lungs 2.  After 5 min of ventilation at a

peak airway pressure of 45 cmH2O

3.  After 20 min of ventilation at a peak airway pressure of 45 cmH2O

Malhorta A. NEJM 2007; 357 (11): 1113-1120

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Background  

Lucangelo U, et al. Minerva Anestesiol 2003; 69 (11): 841-848 Esan A, et al. Chest 2010; 137 (5): 1203-1216  

§  High Frequency Percussive Ventilation (HFPV) Developed 30 years ago by Dr. Forest Bird

   Volumetric Diffusive Respirator (VDR)

ú  Flow-regulated, pressure-limited, and time-cycled

ú  Combination of high-frequency oscillatory ventilation (HFOV) and conventional pressure-limited breathing cycles

ú  Currently utilized as a rescue mode in patients failing conventional ventilation (CV)

ALI  /  ARDS      consequences  

 ◊    REDUCED  SURFACTANT  PRODUCTION  DUE  TO  TYPE  II  CELL  

INJURY.  

 

◊    SURFACTANT  INACTIVATION  BY  PLASMA  PROTEINS  

 ◊    INCREASED  SURFACE  TENSION:    

 *  MICROATELECTASIS    *  SMALL  AIRWAY  COLLAPSE      

MECHANICAL VENTILATION AND ALI/ARDS

◊ BECAUSE LUNG INJURY IS NON-HOMOGENOUS, VENTILATION IS DISTRIBUTED UNEVENLY. ◊ VENTILATION IS DISTRIBUTED TO THE REGIONS OF GREATEST COMPLIANCE AND THE LEAST RESISTANCE OR THE PREFERENTIAL AIRWAY. WHEN THIS MAL-DISTRIBUTION OF VENTILATION DOES FURTHER LUNG DAMAGE THIS IS KNOWN AS (VILI).

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V.A.L.I

V.I.L.I.

BAROTRAUMA Injury due to

Airway Pressure

VOLUTRATTRAUMA

Injury due to Lug Volume

ATELECTRAUMA Injury due to Cyclical Opening &

Closing of lung units

BIOTRAUMA Activation & Release of Inflammatory mediators (Cytokine, Neutrophil.)

High Frequency Percussive Ventilation Volumetric Diffusive Respirator      

§  Definition  ú  Flow-­‐regulated,  pressure-­‐limited  and  time-­‐cycled  ventilation  

ú  Delivers  a  series  of  high-­‐frequency  small  volumes  in  a  successive  stepwise  stacking  pattern  resulting  in  formation  of  low-­‐frequency  convective  pressure-­‐limited  breathing  cycles  

Volumetric  Diffusive  Respirator  

•     Gently  recruits  alveoli  • Keeps  alveoli  patent  

•     Mobilizes  secre5ons  

•     Well  tolerated  by  pa5ents  • No  need  for  paralysis  or  seda5on  

•     No  known  contraindica5ons      

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Can  be  applied  §  ARDS  with  severe  hypoxia  and/or  hypercarbia  §  Severe  unilateral  lung  injury    §  Persistent  lobar  collapse  due  to  secretions  §  Refractory  bronchopleural  fistula  §  Inhalation  injury  or  airway  debris    

ú  in  burn  patients  §  Cystic  Fibrosis  §  Neuromuscular  weakness  

ú  Post  surgical  patients  

VDR-­‐Characteristics  n Pneumatically  powered    n Combines  regular  breath  cycle  with  high  frequency  flow  interruption  during  that  cycle  n Respiratory  rate  2-­‐30  cycles/min    n Inspiratory  and  expiratory  oscillation  o Range  of  frequency  200-­‐900  cycles/min  

VDR  -­‐  Characteristics  n Flow  regulated    

n   see  chest  vibration    n Pressure  limited            Delivery  of  tidal  volume  (Vt)  is  completed  when  the  peak    

inspiratory  pressure  is  reached  

n Fluctuation  in  flow  will  effect  Vt  and  peak  pressure  n Time  cycled              Can  take  spontaneous  breaths  at  any  point  

n Exhalation  is  passive  n Step  wise    deflation  of  the  lung  to  CPAP  level  

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Resonant  Frequency  §  The  ventilator  frequency  at  which  there  is  the  

least  amount  of  impedance  to  gas  flow  into  and  out  of  the  lungs  ú  Using  the  least  amount  of  force  (pressure)  for  the  

maximum  amount  of  penetration  (volume  delivery)  

§  This  ideal  frequency  would  be  when  maximum  CO2  removal  is  achieved  for  a  given  tidal  volume  

§  This  is  achieved  by  the  functional  properties  of  the  phasitron  

 

HFPV  Static  Waveform  VDR  

A"Pulsatile flow during inspiration at 655cycles/min B"Convective pressure-limited breath with low frequency cycle C"Demand CPAP D"Oscillatory CPAP E"Single percussive breath F"Periodic programmed interruptions signifying end of inspiration and onset of exhalation

A

B B

C D

E

F

Action  of  the  phasitron  during  obstruction  

§   Based  on  the  sliding  venturi  principle    

ú  Sliding  ventury  will  entrain  less  gas  ú  Total  flow  output  will  decrease  

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Response  to  obstruction  

§  Vibration  of  the  chest  is  diminished  §  Force  of  the  pulsation  of  the  phasitron  is  reduced  ú  Flow  is  reduced  

   Vt  is  decreased  §  With  ongoing  pulsation  of  the  phasitron  

ú   small  opening  is  created  in  the  airways  ú  achieves  full  opening/ventilation  

   Similar  principle  as  in  clearing  the  secretions  

Advantages  

§  No  termination  of  the  ventilation  §  No  high  peak  airway  pressure  §  No  shearing  forces  §  No  ventilation  induced  lung  injury  §  Able  to  gently  reopen  the  airways    

Considerations  

§  Need  to  monitor  the  patient  ú  See  the  decrease  in  chest  vibrations  

§  Partially  deflate  the  cuff  to  evacuate  secretions  

§  Suction  the  secretions  §  May  consider  bronchoscopy  to  facilitate  the  clearing  of  the  secretions    

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Setting  up  the  VDR  §  Set  up  the  following;    §  Pulsatile  Flow  Rate,  Oscillatory  CPAP,  Convective  Rate,  Percussive  Rate,  Convective  I:E  Ratio,  Percussive  I:E  Ratio  and  FiO2.  

§   Demand  CPAP  if  necessary,  §   Convective  Pressure  Rise  if  necessary.  

§  Don’t  set  the  Vt  §  Monitor  ú O2  Saturation  ú   Patient’s  Chest  Vibrations  ú     Chest  X-­‐rays  ú     ABG’s  

High-­‐frequency  percussive  ventilation  and  low  tidal  volume  ventilation  in  burns:  A  randomized  controlled  trial*  §  Objectives: §  In select burn intensive care units, high-frequency

percussive ventilation is preferentially used to provide mechanical ventilation in support of patients with acute lung injury, acute respiratory distress syndrome, and inhalation injury. However, we found an absence of prospective studies comparing high frequency percussive ventilation with contemporary low-tidal vol- ume ventilation strategies. The purpose of this study was to prospectively compare the two ventilator modalities in a burn intensive care unit setting

§  .Design: §  Single-center, prospective, randomized, controlled

clinical trial, comparing high-frequency percussive ventilation with low-tidal volume ventilation in patients admitted to our burn intensive care unit with respiratory failure.Setting: A 16-bed burn intensive care unit at a tertiary military teaching hospital.

§  Interventions §  : Subjects were randomly assigned to receive

mechanical ventilation through a high-frequency percussive ven- tilation-based strategy (n ! 31) or a low-tidal volume ventilation- based strategy (n ! 31).

§  Conclusions: §  A high-frequency percussive

ventilation-based strategy resulted in similar clinical outcomes when compared with a low-tidal volume ventilation-based strategy in burn pa- tients with respiratory failure.

§  However, the low-tidal volume ventilation strategy failed to achieve ventilation and oxygenation goals in a higher percentage necessitating rescue ventilation

§  Kevin K. Chung, MD; Steven E. Wolf, MD; Evan M. Renz, MD; Patrick F. Allan, MD; James K. Aden, PhD; Gerald A. Merrill, PhD; Mehdi C. Shelhamer, DO; Booker T. King, MD; Christopher E. White, MD; David G. Bell, MD; Martin G. Schwacha, PhD; Sandra M. Wanek, MD; Charles E. Wade, PhD; John B. Holcomb, MD; Lorne H. Blackbourne, MD; Leopoldo C. Cancio, MD.

§  (CritCareMed 2010;38:1970 –1977)

DOI 10.1378/chest.09-2415 2010;137;1203-1216Chest

Curtis N. SesslerAdebayo Esan, Dean R. Hess, Suhail Raoof, Liziamma George and

Ventilatory Strategies!!1Severe Hypoxemic Respiratory Failure : Part

http://chestjournal.chestpubs.org/content/137/5/1203.full.html

services can be found online on the World Wide Web at: The online version of this article, along with updated information and

ISSN:0012-3692)http://chestjournal.chestpubs.org/site/misc/reprints.xhtml(

of the copyright holder.may be reproduced or distributed without the prior written permission Northbrook, IL 60062. All rights reserved. No part of this article or PDFby the American College of Chest Physicians, 3300 Dundee Road,

2010Physicians. It has been published monthly since 1935. Copyright is the official journal of the American College of ChestCHEST

© 2010 American College of Chest Physicians at Duke University on May 4, 2010chestjournal.chestpubs.orgDownloaded from

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             Chest,  May  2010    

Summary  

§  Combination  of  regular  breath  cycles  with  high  frequency  flow  interruption    ú  Achieves  the  properties  of  conventional  and  high  frequency  ventilations  

§  Well  tolerated  by  the  patients  

§  No  need  for  sedation  or  paralytics      

Summary  

§  Allows  to  ú  Gently  open  alveoli  ú  Keep  them  patent  ú  Reduce  barotrauma/volutrauma  in  ARDS  ú  Mobilizes  secretions    ú  Overcomes  obstruction  ú  Can  be  used  in  any  circumstances,  which  requires  ventilation     Invasive  and  non-­‐invasive  

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PATIENT:

"Doctor, doctor, will I be able to play the violin after the

operation?" Doctor:

"Yes, of course..."

Patient:

"Great! I never could before!"

§                     

§                                               THANK  YOU