Post on 20-May-2020
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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!"
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