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MMechanical ventilation is the echanical ventilation is the cornerstone of supportive care for cornerstone of supportive care for acute respiratory failure. acute respiratory failure.

In most patients, adequate gas In most patients, adequate gas exchange can be ensured while more exchange can be ensured while more specific treatments are administered. specific treatments are administered.

04/21/2304/21/23 33

Conventional Ventilation, its Conventional Ventilation, its limitations & development limitations & development

of HFVof HFV

04/21/2304/21/23 44

High airway pressures,High airway pressures, Circulatory depression, and Circulatory depression, and Pulmonary air leaks.Pulmonary air leaks.

04/21/2304/21/23 55

In patients with acute lung injury In patients with acute lung injury (ALI) and ARDS, conventional (ALI) and ARDS, conventional mechanical ventilation (CV) may mechanical ventilation (CV) may cause additional lung injury.cause additional lung injury.

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Pressure Volume CurvePressure Volume Curve

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Changing Lung Volume In CVChanging Lung Volume In CV

Paw = Lung Volume

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CDP= FRC

CT 1 CT 2CT 3

Paw = CDP

ContinuousDistendingPressure

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Volume

Pressure

Zone ofOverdistention

“Safe”Window

Zone ofDerecruitment

and Atelectasis

Injury

Injury

Optimized Lung Volume “Safe Window”Optimized Lung Volume “Safe Window” Overdistension Overdistension

• Edema fluid accumulationEdema fluid accumulation• Surfactant degradationSurfactant degradation• High oxygen exposureHigh oxygen exposure• Mechanical disruptionMechanical disruption

Derecruitment AtelectasisDerecruitment Atelectasis• Repeated closure / re-Repeated closure / re-

expansionexpansion• Stimulation inflammatory Stimulation inflammatory

responseresponse• Inhibition surfactantInhibition surfactant• Local hypoxemiaLocal hypoxemia• Compensatory Compensatory

overexpansion overexpansion

04/21/2304/21/23 1010

An alternate mode of ventilation may be An alternate mode of ventilation may be instituted in an attempt to provide instituted in an attempt to provide adequate gas exchange and limit adequate gas exchange and limit ventilator-induced lung injury. Approaches ventilator-induced lung injury. Approaches used in patients with severe lung injury used in patients with severe lung injury include:include:

Inverse ratio ventilationInverse ratio ventilation Pressure-limited ventilationPressure-limited ventilation Airway pressure release ventilationAirway pressure release ventilation Recruitment maneuversRecruitment maneuvers Prone positioningProne positioning High frequency ventilationHigh frequency ventilation Nitric oxideNitric oxide Extracorporeal CO2 removal and ECMOExtracorporeal CO2 removal and ECMO

04/21/2304/21/23 1111

These adverse effects stimulated the These adverse effects stimulated the development of high-frequency development of high-frequency ventilation (HFV). ventilation (HFV).

(There was great enthusiasm for HFV (There was great enthusiasm for HFV during its early development in the during its early development in the 1970s and 1980s). 1970s and 1980s).

04/21/2304/21/23 1212

However, the initial enthusiasm for However, the initial enthusiasm for HFV waned as clinical studies failed HFV waned as clinical studies failed to demonstrate important to demonstrate important advantages over Conventional advantages over Conventional Ventilation.Ventilation.

04/21/2304/21/23 1313

There is now renewed interest in HFV There is now renewed interest in HFV because of increasing evidence that because of increasing evidence that

(1) CV may contribute to lung injury (1) CV may contribute to lung injury in patients with acute lung injury in patients with acute lung injury (ALI) and ARDS(ALI) and ARDS

(2) modifications of mechanical (2) modifications of mechanical

ventilation techniques may prevent ventilation techniques may prevent or reduce lung injury and improve or reduce lung injury and improve clinical outcomes in these patients.clinical outcomes in these patients.

04/21/2304/21/23 1414

Potential role of HFVPotential role of HFV

Achieving adequate gas exchange Achieving adequate gas exchange while protecting the lung against while protecting the lung against further injury in patients with further injury in patients with ALI/ARDS.ALI/ARDS.

TI - Use of ultrahigh frequency ventilation in patients with ARDS. A preliminary report.AU - Gluck E; Heard S; Patel C; Mohr J; Calkins J; Fink MP; Landow LSO - Chest 1993 May;103(5):1413-20.

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IntroductionIntroduction

HFV is a mode of mechanical HFV is a mode of mechanical ventilation that uses rapid ventilation that uses rapid respiratory rates (respiratory rate [respiratory rates (respiratory rate [ff] ] more than four times the normal more than four times the normal rate) and small Vts. rate) and small Vts.

04/21/2304/21/23 1616

Variations of HFVVariations of HFV

These may be broadly classified asThese may be broadly classified as

1.1. high-frequency positive pressure high-frequency positive pressure ventilation (HFPPV), ventilation (HFPPV),

2.2. high-frequency jet ventilation high-frequency jet ventilation (HFJV), and(HFJV), and

3.3. high-frequency oscillation (HFO).high-frequency oscillation (HFO).

04/21/2304/21/23 1717

HFPPVHFPPV HFPPV was introduced by Oberg and Sjostrand HFPPV was introduced by Oberg and Sjostrand

in 1969.in 1969.

HFPPV delivers small Vts (approximately 3 to HFPPV delivers small Vts (approximately 3 to 4 mL/kg) of conditioned gas at high flow rates 4 mL/kg) of conditioned gas at high flow rates (175 to 250 L/min) and frequency ((175 to 250 L/min) and frequency (ff, 60 to 100 , 60 to 100 breaths/min).breaths/min).

04/21/2304/21/23 1818

The precise Vt is difficult to measure.The precise Vt is difficult to measure. Expiration is passive and depends on Expiration is passive and depends on

lung and chest wall elastic recoil.lung and chest wall elastic recoil. Thus, with high Thus, with high ff, there is a risk of , there is a risk of

gas trapping with over distention of gas trapping with over distention of some lung regions and adverse some lung regions and adverse circulatory effects.circulatory effects.

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HFJVHFJV Sanders introduced Sanders introduced HFJV in 1967 to HFJV in 1967 to facilitate gas facilitate gas exchange during exchange during rigid bronchoscopy.rigid bronchoscopy.

In HFJV, gas under In HFJV, gas under high pressure (15 high pressure (15 to 50 lb per square to 50 lb per square inch)is introduced inch)is introduced through a small-through a small-bore cannula or bore cannula or aperture(14 to 18 aperture(14 to 18 gauge) into the gauge) into the upper or middle upper or middle portion of the portion of the endotracheal tube.endotracheal tube.

04/21/2304/21/23 2020

Pneumatic, fluid, or Pneumatic, fluid, or solenoid valves solenoid valves control the control the intermittent intermittent delivery of the gas delivery of the gas jets.jets.

Aerosolized saline Aerosolized saline solution in the solution in the inspiratory circuit is inspiratory circuit is used to humidify used to humidify the inspired air.the inspired air.

Some additional gas Some additional gas is entrained during is entrained during inspiration from a inspiration from a side port in the side port in the circuit.circuit.

04/21/2304/21/23 2121

This form of HFV generally delivers a This form of HFV generally delivers a Vt of 2 to 5 mL/kg at a Vt of 2 to 5 mL/kg at a f f of 100 to of 100 to 200 breaths/min.200 breaths/min.

The jet pressure (which determines The jet pressure (which determines the velocity of air jets) and the the velocity of air jets) and the duration of the inspiratory jet (and, duration of the inspiratory jet (and, thus, the inspiratory/expiratory ratio thus, the inspiratory/expiratory ratio [I/E]) are controlled by the operator.[I/E]) are controlled by the operator.

04/21/2304/21/23 2222

Together, the jet velocity and Together, the jet velocity and duration determine the volume of duration determine the volume of entrained gas.entrained gas.

Thus, the Vt is directly proportional Thus, the Vt is directly proportional to the jet pressure and I/E.to the jet pressure and I/E.

04/21/2304/21/23 2323

As with HFPPV, expiration is passive. As with HFPPV, expiration is passive. Thus, HFJV may cause air trapping.Thus, HFJV may cause air trapping.

04/21/2304/21/23 2424

High Frequency OscillationHigh Frequency Oscillation

Lunkenheimer et al introduced HFO Lunkenheimer et al introduced HFO in 1972.in 1972.

HFO uses reciprocating pumps or HFO uses reciprocating pumps or diaphragms.diaphragms.

Thus, in contrast to HFPPV and HFJV, Thus, in contrast to HFPPV and HFJV, both expiration and inspiration are both expiration and inspiration are active processes during HFO.active processes during HFO.

04/21/2304/21/23 2525

HFO Vts are approximately 1 to 3 HFO Vts are approximately 1 to 3 mL/kg at mL/kg at ffs up to 2,400 breaths/min.s up to 2,400 breaths/min.

The operator sets the The operator sets the ff, the I/E , the I/E (typically approximately 1:2), driving (typically approximately 1:2), driving pressure, and mean airway pressure pressure, and mean airway pressure (MAP).(MAP).

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The oscillatory Vts are directly The oscillatory Vts are directly related to driving pressures.related to driving pressures.

In contrast, Vts are inversely related In contrast, Vts are inversely related to to frequency.frequency.

The inspiratory bias flow of air into The inspiratory bias flow of air into

the airway circuit is adjusted to the airway circuit is adjusted to achieve the desired MAPachieve the desired MAP

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Frequency controls the time allowed (distance) for the piston to move. Therefore, the lower the frequency , the greater the volume displaced, and the higher the frequency , the smaller the volume displaced.

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CDP=FRC=Oxygenation

HFOV Principle:HFOV Principle:

+ + + + +

- - - - -

AmplitudeDelta P =Tv =Ventilation

I

E

HFOV = CPAP with a wiggle !

04/21/2304/21/23 3030

Pressure transmission CMV / HFOV Pressure transmission CMV / HFOV

Distal amplitude Distal amplitude measurements with measurements with alveolar capsules in alveolar capsules in animals, demonstrate it animals, demonstrate it to be greatly reduced to be greatly reduced or “attenuated” as the or “attenuated” as the pressure traverses pressure traverses through the airways.through the airways.

Due to the attenuation Due to the attenuation of the pressure wave, of the pressure wave, by the time it reaches by the time it reaches the alveolar region, it is the alveolar region, it is reduced down to .1 - 5 reduced down to .1 - 5 cmH2O.cmH2O.

Gerstman et al

04/21/2304/21/23 3131

Pressure transmission HFOV Pressure transmission HFOV

P

T

proximal

trachea

alveoli

04/21/2304/21/23 3232

Advantages of HFOAdvantages of HFO1.1. There is no gas entrainment or There is no gas entrainment or

decompression of gas jets in the airway, decompression of gas jets in the airway, allowing better humidification and warming allowing better humidification and warming of inspired air.of inspired air.

2.2. The risks of airway obstruction from The risks of airway obstruction from desiccated airway secretions is lower.desiccated airway secretions is lower.

3.3. In addition, active expiration permits better In addition, active expiration permits better control of lung volumes than with HFPPV and control of lung volumes than with HFPPV and HFJV, decreasing the risk of air trapping, HFJV, decreasing the risk of air trapping, overdistention of airspaces, and circulatory overdistention of airspaces, and circulatory depression.depression.

4.4. Lower I/Es (1:2 or 1:3) reduce the risk of air Lower I/Es (1:2 or 1:3) reduce the risk of air trapping.trapping.

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Selected Features of CV & HFVSelected Features of CV & HFV

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Gas Transport During Gas Transport During HFVHFV

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1.Direct Bulk Flow1.Direct Bulk Flow Some alveoli situated Some alveoli situated

in the proximal in the proximal tracheobronchial tree tracheobronchial tree receive a direct flow receive a direct flow of inspired air. This of inspired air. This leads to gas leads to gas exchange by exchange by traditional traditional mechanisms of mechanisms of convective or convective or bulk bulk flow.flow.

04/21/2304/21/23 3636

2.Longitudinal (Taylor) Dispersion2.Longitudinal (Taylor) Dispersion Turbulent eddies and Turbulent eddies and

secondary swirling secondary swirling motions occur when motions occur when convective flow is convective flow is superimposed on superimposed on diffusion. Some fresh diffusion. Some fresh gas may mix with gas gas may mix with gas from alveoli, from alveoli, increasing the increasing the amount of gas amount of gas exchange that would exchange that would occur from simple occur from simple bulk flow.bulk flow.

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3.Pendeluft3.Pendeluft

Units can mutually exchange gas, an effect known as pendeluft. By way of this mechanism even very small fresh-gas volumes can reach a large number of alveoli and regions

04/21/2304/21/23 3838

04/21/2304/21/23 3939

4.Asymmetric Velocity Profiles4.Asymmetric Velocity Profiles The velocity profile of air The velocity profile of air

moving through an airway moving through an airway under laminar flow under laminar flow conditions is parabolic.conditions is parabolic.

Air closest to the Air closest to the tracheobronchial wall has a tracheobronchial wall has a lower velocity than air in the lower velocity than air in the center of the airway lumen. center of the airway lumen.

This parabolic velocity This parabolic velocity profile is usually more profile is usually more pronounced during the pronounced during the inspiratory phase of inspiratory phase of respiration because of respiration because of differences in flow rates.differences in flow rates.

04/21/2304/21/23 4040

With repeated respiratory cycles, gas in the With repeated respiratory cycles, gas in the center of the airway lumen advances further center of the airway lumen advances further into the lung while gas on the margin (close to into the lung while gas on the margin (close to the airway wall) moves out toward the mouth.the airway wall) moves out toward the mouth.

04/21/2304/21/23 4141

During inspiration, the During inspiration, the high frequency pulse high frequency pulse creates a bullet shaped creates a bullet shaped profile with the central profile with the central molecules moving molecules moving further down the air way further down the air way than those molecules than those molecules found on the periphery found on the periphery of the airway.of the airway.

On exhalation, the On exhalation, the velocity profile is blunted velocity profile is blunted so that at the completion so that at the completion of each return , the of each return , the central molecules remain central molecules remain further down the airway further down the airway and the peripheral and the peripheral molecules move towards molecules move towards the mouth of the airway. the mouth of the airway.

04/21/2304/21/23 4242

5.Cardiogenic Mixing5.Cardiogenic Mixing

Mechanical Mechanical agitation from the agitation from the contracting heart contracting heart contributes to gas contributes to gas mixing, especially mixing, especially in peripheral lung in peripheral lung units in close units in close proximity to the proximity to the heart.heart.

04/21/2304/21/23 4343

6.Molecular Diffusion6.Molecular Diffusion

As in other modes As in other modes of ventilation, this of ventilation, this mechanism may mechanism may play an important play an important role in mixing of air role in mixing of air in the smallest in the smallest bronchioles and bronchioles and alveoli, near the alveoli, near the alveolocapillary alveolocapillary membranes.membranes.

04/21/2304/21/23 4444

ALI/ARDSALI/ARDS

04/21/2304/21/23 4545

04/21/2304/21/23 4646

Chest Radiographs & CT Images Chest Radiographs & CT Images

04/21/2304/21/23 4747

Patients with ALI/ARDS frequently Patients with ALI/ARDS frequently develop acute respiratory failure.develop acute respiratory failure.

Physiologic dead space typically is Physiologic dead space typically is also elevated, which increases the also elevated, which increases the minute ventilation required to minute ventilation required to maintain normal arterial Paco2 and maintain normal arterial Paco2 and pH.pH.

TI - High-frequency percussive ventilation improves oxygenation in trauma patients with acute respiratory distress syndrome: a retrospective review.AU - Eastman A; Holland D; Higgins J; Smith B; Delagarza J; Olson C; Brakenridge S; Foteh K; Friese RSO - Am J Surg. 2006 Aug;192(2):191-5.

04/21/2304/21/23 4848

Our Rescue here is Our Rescue here is Mechanical VentilationMechanical Ventilation

BUT IT IS NOT EASYBUT IT IS NOT EASY

04/21/2304/21/23 4949

Ventilator Associated Lung InjuryVentilator Associated Lung Injury

Uneven distribution of Tidal VolumesUneven distribution of Tidal Volumes

Pro inflammatory mediatorsPro inflammatory mediators

04/21/2304/21/23 5050

Mechanisms of VALI in ALI/ARDSMechanisms of VALI in ALI/ARDS

1.1. Ventilation of lung regions with higher Ventilation of lung regions with higher compliance may be injured by excessive compliance may be injured by excessive regional end inspiratory lung volumes regional end inspiratory lung volumes (EILVs).(EILVs).

2.2. Injury may occur in small bronchioles when Injury may occur in small bronchioles when they snap open during inspiration and close they snap open during inspiration and close during expiration. during expiration.

3.3. Pulmonary parenchyma at the margins Pulmonary parenchyma at the margins between atelectatic and aerated units may between atelectatic and aerated units may be injured by excessive stress from the be injured by excessive stress from the interdependent connections between interdependent connections between adjacent units.adjacent units.

04/21/2304/21/23 5151

These last two mechanisms are These last two mechanisms are frequently described with the term frequently described with the term shear forces shear forces and may be important and may be important mechanisms of lung injury when mechanisms of lung injury when ventilation occurs with relatively low ventilation occurs with relatively low end expiratory lung volumes (EELVs) end expiratory lung volumes (EELVs) in patients with ALI/ARDS.in patients with ALI/ARDS.

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Injury From Excessive EILVsInjury From Excessive EILVs

The lungs of patients with ALI/ARDS The lungs of patients with ALI/ARDS are susceptible to excessive regional are susceptible to excessive regional EILV and over distention injuryEILV and over distention injury

High inspiratory airway pressures High inspiratory airway pressures

(peak and plateau). (peak and plateau).

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VolutraumaVolutrauma

Excessive lung stretch, rather than Excessive lung stretch, rather than pressure, is more likely to be the pressure, is more likely to be the injurious force. injurious force.

Thus, there is increasing use of the Thus, there is increasing use of the term term volutrauma volutrauma to refer to the to refer to the stretch-induced injury of excessive stretch-induced injury of excessive inspiratory gas volume.inspiratory gas volume.

04/21/2304/21/23 5454

Injury From Ventilation at Low Injury From Ventilation at Low EELVsEELVs

Positive end-expiratory pressure (PEEP) has lung protective effects during mechanical ventilation in isolated lungs, and in intact and open-chest animals.

04/21/2304/21/23 5555

Effect of PEEP on edema with large lung volumes

Injury caused by ventilation with large Vt and low PEEP.

Effects of smaller Vts and higher PEEPs despite similar EILVs.

The effect of end-expiratory atelectasis on lung injury.

04/21/2304/21/23 5656

PEEP Good Or BadPEEP Good Or Bad

04/21/2304/21/23 5757

These and other studies provide convincing evidence that PEEP has lung protective effects during mechanical ventilation.

However, PEEP also can contribute to lung injury by raising EILV unless Vt is simultaneously reduced.

Moreover, PEEP may cause circulatory depression from increased pulmonary vascular resistance and decreased venous return.

04/21/2304/21/23 5858

CV-Based Lung Protective Strategies

CV strategies designed to protect the lung from VALI have been tested in several clinical trials.

04/21/2304/21/23 5959

Studies With Reduced EILV In two case series of patients with

severe ARDS (a total of approximately 100 patients), ventilation with small Vts (reduced EILVs) was associated with mortality rates that were substantially lower than rates predicted from the patients’ acute physiology and chronic health evaluation (APACHE) II scores.

Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med 2000; 342:1301.

04/21/2304/21/23 6060

In contrast A large multicenter trial with 861

patients with ALI/ARDS found substantial improvements in clinical outcomes in the small Vt group.

The mortality rate prior to discharge home with unassisted breathing was significantly reduced (31% vs 40%, respectively; p , 0.01) among patients randomized to the small Vt strategy.

04/21/2304/21/23 6161

Studies With Reduced EILV and Increased EELV

A clinical trial in 53 patients with A clinical trial in 53 patients with severe ARDS compared a traditional severe ARDS compared a traditional CV approach with an approach CV approach with an approach designed to protect the lung from designed to protect the lung from VALI resulting from both excessive VALI resulting from both excessive EILV and inadequate EELV. EILV and inadequate EELV.

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In the lung-protection group, pressure In the lung-protection group, pressure limited modes were used with Vts # 6 limited modes were used with Vts # 6 mL/kg and peak inspiratory pressures 40 mL/kg and peak inspiratory pressures 40 cm H20 to reduce EILV. Increased EELV cm H20 to reduce EILV. Increased EELV was achieved, raising PEEP.was achieved, raising PEEP.

Frequent recruitment maneuvers wereFrequent recruitment maneuvers were introduced to further increase EELV, and introduced to further increase EELV, and

additional measures were taken to avoid additional measures were taken to avoid undesirable collapse or derecruitment of undesirable collapse or derecruitment of some lung regions. some lung regions.

04/21/2304/21/23 6363

The lung protection approach was associated with an improved 28-day survival rate and weaning rate.

In hospital mortality rate was also reduced

Brower RG, Shanholtz CB, Fessler HE, et al. Prospective randomized, controlled clinical trial comparing traditional vs reduced tidal volume ventilation in ARDS patients. Crit CareMed 1999; 27:1492–1498

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Summary Lung Protective Modes of CV

The body of experimental evidence strongly suggests that a lung protective strategy with smaller EILV and higher EELV will reduce VALI and improve outcomes in patients with ALI/ARDS.

04/21/2304/21/23 6565

Limitations Increasing EELV (with higher PEEPs),

especially when it is used in combination with lower EILVs (smaller Vts) during CV may cause

hypoventilation respiratory acidosis Dyspnea circulatory depression increased cerebral blood flow & risk for intracranial hypertension increase the requirements for heavy

sedation and neuromuscular blockade.

04/21/2304/21/23 6666

Rationale for HFV-Based Lung Protective

Strategies

04/21/2304/21/23 6767

HFV Advantages over CV

1. HFV uses very small VTs. This allows the use of

higher EELVs to achieve greater levels of lung

recruitment while avoiding injury from excessive

EILV.

2. Respiratory rates with HFV are much higher

than with CV. This allows the maintenance of

normal or near-normal Paco2 levels, even with

very small Vts.TI - High-frequency percussive ventilation improves oxygenation in trauma patients with acute respiratory distress syndrome: a retrospective review.AU - Eastman A; Holland D; Higgins J; Smith B; Delagarza J; Olson C; Brakenridge S; Foteh K; Friese RSO - Am J Surg. 2006 Aug;192(2):191-5.

04/21/2304/21/23 6868

HFOV PrincipleHFOV PrinciplePressure curves CMV / HFOVPressure curves CMV / HFOV

04/21/2304/21/23 6969

Adults Studies

HFJV was compared to CV in a randomized trial of 309 oncology patients with body weight > 20 kg and respiratory failure requiring mechanical ventilation

In another study, 113 surgical ICU patients at risk for ARDS were randomized to high-frequency percussive ventilation (HFPV) or CV

In a 1997 case series, 17 medical and surgical patients (age range, 17 to 83 years) with severe ARDS

04/21/2304/21/23 7070

Conclusion

04/21/2304/21/23 7171

Small Vt ventilation to reduce EILV during CV recently has shown to improve mortality when compared to a more traditional Vt approach.

There is also abundant evidence in experimental animals and, more recently, in humans to suggest that there are lung protective effects with higher EELV.

HFV, especially HFO, offers the best opportunity to achieve greater lung recruitment without overdistention while maintaining normal or near-normal acid-base parameters.

04/21/2304/21/23 7272

Starting on HFOStarting on HFO

TI - A protocol for high-frequency oscillatory ventilation in adults: results from a roundtable discussion.

SO - Crit Care Med. 2007 Jul;35(7):1649-54.AU - Fessler HE; Derdak S; Ferguson ND; Hager DN; Kacmarek RM; Thompson BT; Brower RG

04/21/2304/21/23 7373

04/21/2304/21/23 7474

Diagrammatic RepresentationDiagrammatic Representation

04/21/2304/21/23 7575

SensorMedics SensorMedics 3100B3100B

Electrically powered, Electrically powered, electronically electronically controlled piston-controlled piston-diaphragm oscillator diaphragm oscillator

Paw of 5 - 55 cmH2OPaw of 5 - 55 cmH2O Pressure Amplitude Pressure Amplitude

from 8 - 130 cmH2Ofrom 8 - 130 cmH2O Frequency of 3 - 15 HzFrequency of 3 - 15 Hz % Inspiratory Time % Inspiratory Time

30% - 50%30% - 50% Flow rates from 0 - 60 Flow rates from 0 - 60

LPMLPM

04/21/2304/21/23 7676

IndicationsIndications

Diffuse alveolar disease associated Diffuse alveolar disease associated with decreased lung compliance, with decreased lung compliance, hypoxemia & Oxygen index > 30hypoxemia & Oxygen index > 30

Oxygen index=FiO2*Paw/PaO2*100Oxygen index=FiO2*Paw/PaO2*100 Pulmonary barotrauma with air leak Pulmonary barotrauma with air leak

syndromesyndrome CXR: PneumothoraxCXR: Pneumothorax PneumomediastinumPneumomediastinum pneumoperitoneumpneumoperitoneum

04/21/2304/21/23 7777

ContraindicationsContraindications

Heterogenous lung diseaseHeterogenous lung disease Increased expiratory resistanceIncreased expiratory resistance

04/21/2304/21/23 7878

InitiationInitiation

1. Connect patient to HFO circuit1. Connect patient to HFO circuit 2. FiO2 100%2. FiO2 100% 3. Perform recruitment maneuvers3. Perform recruitment maneuvers

TI - Tidal volume delivery during high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome.

SO - Crit Care Med. 2007 Jun;35(6):1522-9.AU - Hager DN; Fessler HE; Kaczka DW; Shanholtz CB; Fuld MK; Simon BA; Brower RG

04/21/2304/21/23 7979

Initial SettingsInitial Settings

1. FiO2 100%1. FiO2 100% 2. I:E 1:2 ( Inspiratory Time 33%)2. I:E 1:2 ( Inspiratory Time 33%) 3. Bias Flow 40 liters/min3. Bias Flow 40 liters/min 4. Pressure amplitude (∆P)4. Pressure amplitude (∆P) 90cmH2O90cmH2O 5. mPaw 30 cm of H2O5. mPaw 30 cm of H2O 6. frequency is determined by 6. frequency is determined by

arterial pH immediately prior to HFOarterial pH immediately prior to HFO

04/21/2304/21/23 8080

pH & frequencypH & frequency

<7.10 3-5Hz<7.10 3-5Hz 7.10-7.19 4Hz7.10-7.19 4Hz 7.20-7.35 5Hz7.20-7.35 5Hz >7.35 6Hz>7.35 6Hz

04/21/2304/21/23 8181

OxygenationOxygenation

Target SpO2 88-93% & PaO2 55-80mmHg Target SpO2 88-93% & PaO2 55-80mmHg After initial RM decrease FiO2 in 0.05-0.1 After initial RM decrease FiO2 in 0.05-0.1

decrements Q2-5 minutes to target SpO2 88-decrements Q2-5 minutes to target SpO2 88-9393

If resultant FiO2 is <0.60, adjust mPaw If resultant FiO2 is <0.60, adjust mPaw according to the following chart but if SpO2 according to the following chart but if SpO2 falls and you have to increase FiO2 above falls and you have to increase FiO2 above 0.60:0.60:

Perform a 2Perform a 2ndnd RM RM Reinitiate HFO with mPaw 34cmH2OReinitiate HFO with mPaw 34cmH2O Follow the chart again Follow the chart again

04/21/2304/21/23 8282

Algorithm to followAlgorithm to followStepStep 11 22 33 44 55 66 77 88 99 1010 1111 1212 1313 1414 1515 1616

FiO2FiO2 0.40.4 0.40.4 0.40.4 0.40.4 0.40.4 0.40.4 0.50.5 0.60.6 0.60.6 0.60.6 0.70.7 0.80.8 0.90.9 1.01.0 1.01.0 1.01.0

mPawmPaw 2020 2222 2424 2626 2828 3030 3030 3030 3232 3434 3434 3434 3434 3434 3636 3838

Fluctuation of 5 cm of H2O around set mPaw Fluctuation of 5 cm of H2O around set mPaw allowable unless oxygenation or ventilation is allowable unless oxygenation or ventilation is compromised; otherwise increase sedation.compromised; otherwise increase sedation.

Precede each increase in mPaw by a RM. Precede each increase in mPaw by a RM. Physician may discontinue these routine RMs at Physician may discontinue these routine RMs at their discretion after 48 hours in study. Do not their discretion after 48 hours in study. Do not decrease mPaw more than 2 cm H2O Q 2Hrs decrease mPaw more than 2 cm H2O Q 2Hrs

04/21/2304/21/23 8383

If patient develops hypotension during If patient develops hypotension during mPaw titration, stay at lower possible mPaw mPaw titration, stay at lower possible mPaw

1.1. Reduce mPaw to 30 cm 0f H2O or most Reduce mPaw to 30 cm 0f H2O or most recently tolerated, whichever is lower.recently tolerated, whichever is lower.

2.2. Ensure your patient is adequately filled.Ensure your patient is adequately filled.3.3. If patient remains hypotensive despite of If patient remains hypotensive despite of

sufficient preload start pressors.sufficient preload start pressors.4.4. If lungs appear over distended on CXR If lungs appear over distended on CXR

and/or patient is unresponsive to increase and/or patient is unresponsive to increase in mPaw , target a lower mPaw. in mPaw , target a lower mPaw.

5.5. if FiO2 is > 0.70 for > 2 hrs & if FiO2 is > 0.70 for > 2 hrs & intravascular volume is optimized try a intravascular volume is optimized try a lower mPaw.lower mPaw.

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Recruitment Recruitment ManeuversManeuvers

TI - Combining high-frequency oscillatory ventilation and recruitment maneuvers in adults with early acute respiratory distress syndrome: the Treatment with Oscillation and an Open Lung Strategy (TOOLS) Trial pilot study.AU - Ferguson ND; Chiche JD; Kacmarek RM; Hallett DC; Mehta S; Findlay GP; Granton JT; Slutsky AS; Stewart TESO - Crit Care Med. 2005 Mar;33(3):479-86.

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Conventional VentilationConventional Ventilation1.1. Increase FiO2 to 1.0Increase FiO2 to 1.02.2. Set pressure alarm limit to 50 cm H2O.Set pressure alarm limit to 50 cm H2O.3.3. Set apnea alarm to 60 seconds.Set apnea alarm to 60 seconds.4.4. Change to CPAP/PS mode.Change to CPAP/PS mode.5.5. Assure pressure support is set at “0” & Assure pressure support is set at “0” &

tube compensation is “off” ( tube tube compensation is “off” ( tube compensation should always be off for compensation should always be off for HFO patients).HFO patients).

6.6. Increase PEEP to 40 & maintain inflation Increase PEEP to 40 & maintain inflation for 40 seconds.for 40 seconds.

7.7. Lower PEEP to previous set level.Lower PEEP to previous set level.8.8. Resume previous set mode & reset alarm Resume previous set mode & reset alarm

limits.limits.9.9. Lower FiO2 to previous level.Lower FiO2 to previous level.

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When to perform a RM on HFO On initiation of HFO Immediately preceding any increase in

mPAW dictated by the mPAW/FiO2 chart; after day 2 this is optional at the discretion of the attending physician

If a persistent desaturation (SpO2 <88% lasting more than 15 minutes) occurs following an event likely to have caused derecruitment (e.g. suctioning, accidental ventilator disconnection, patient repositioning) ; after day 2 this is optional at the discretion of the attending physician

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Recruitment ManeuversRecruitment Maneuvers for HFO for HFO1.1. Increase FiO2 to 1.0.Increase FiO2 to 1.0.2.2. Set high pressure alarm to 55 cm H2O.Set high pressure alarm to 55 cm H2O.3.3. Pause the oscillating membrane (∆ P=0)Pause the oscillating membrane (∆ P=0)4.4. Eliminate a cuff leak, if present.Eliminate a cuff leak, if present.5.5. Slowly raise mPaw to 40 cm H2O over 10 seconds.Slowly raise mPaw to 40 cm H2O over 10 seconds.6.6. Maintain mPaw = 40 cm H2O for 40 seconds.Maintain mPaw = 40 cm H2O for 40 seconds.7.7. Slowly lower mPaw over 10 seconds,to set level prior Slowly lower mPaw over 10 seconds,to set level prior

to RM if RM was conducted for disconnect or to RM if RM was conducted for disconnect or derecruitment.derecruitment.

8.8. Adjust level higher to previous if RM performed for Adjust level higher to previous if RM performed for persistent hypoxia.persistent hypoxia.

9.9. Resume oscillation & reset alarms.Resume oscillation & reset alarms.10.10. Lower the FiO2.Lower the FiO2.

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VentilationVentilation

Goal pH 7.25-7.35 at highest Goal pH 7.25-7.35 at highest possible frequencypossible frequency

To minimize Vt, maximize frequencyTo minimize Vt, maximize frequency Adjust frequency rather than ∆ P 90 Adjust frequency rather than ∆ P 90

cm H2O to control pH.cm H2O to control pH.

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pH> 7.35pH> 7.35

Increase f by 1 Hz Q 30-60 min to pH Increase f by 1 Hz Q 30-60 min to pH goal or F=10 Hz.goal or F=10 Hz.

Decrease delta P from 90 cm only if Decrease delta P from 90 cm only if f=10 Hz & pH > 7.35 without cuff f=10 Hz & pH > 7.35 without cuff leak. If these criteria are met , leak. If these criteria are met ,

Decrease delta p by 10 cm H2O Q Decrease delta p by 10 cm H2O Q 30-60 min to reach pH goal.30-60 min to reach pH goal.

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pH 7.25 -7.35pH 7.25 -7.35

Use highest possible frequency Use highest possible frequency within this goal range.within this goal range.

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pH 7.15 -7.24pH 7.15 -7.24

Decrease f by 1 Hz Q 30-60 to reach Decrease f by 1 Hz Q 30-60 to reach pH goal or f=4 pH goal or f=4

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pH< 7.15pH< 7.15

Decrease f by 1 Hz Q 30-60 min to Decrease f by 1 Hz Q 30-60 min to pH goal or f=3.pH goal or f=3.

Consider IV bicarb.Consider IV bicarb.

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pH <7.0pH <7.0

Ensure paralysis.Ensure paralysis. If pH remains low for an hour other If pH remains low for an hour other

rescue measure should be sought.rescue measure should be sought.

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WeaningWeaning

Consider Conventional VentilationConsider Conventional Ventilation

FiO2<0.40FiO2<0.40

Amplitude<25 cmH2OAmplitude<25 cmH2O

Frequency 10-15 HzFrequency 10-15 Hz

Paw<20 cmH2OPaw<20 cmH2O

Ti: 33%Ti: 33%

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Important ConsiderationsImportant Considerations

CXRsCXRs Piston centeringPiston centering Sedation & paralysisSedation & paralysis Patient & Circuit positioningPatient & Circuit positioning Air way patencyAir way patency Recruitment maneuvers after suctionRecruitment maneuvers after suction

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ReferencesReferences

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Standiford, TJ, Morganroth, ML. High-frequency Standiford, TJ, Morganroth, ML. High-frequency ventilation. Chest 1989; 96:1380. ventilation. Chest 1989; 96:1380.

Gluck, E, Heard, S, Patel, C, et al. Use of ultrahigh Gluck, E, Heard, S, Patel, C, et al. Use of ultrahigh frequency ventilation in patients with ARDS: A frequency ventilation in patients with ARDS: A preliminary report. Chest 1993; 103:1413. preliminary report. Chest 1993; 103:1413.

Fessler, HE, Derdak, S, Ferguson, ND, et al. A Fessler, HE, Derdak, S, Ferguson, ND, et al. A protocol for high-frequency oscillatory ventilation protocol for high-frequency oscillatory ventilation in adults: results from a roundtable discussion. in adults: results from a roundtable discussion. Crit Care Med 2007; 35:1649. Crit Care Med 2007; 35:1649.

Hager, DN, Fessler, HE, Kaczka, DW, et al. Tidal Hager, DN, Fessler, HE, Kaczka, DW, et al. Tidal volume delivery during high-frequency oscillatory volume delivery during high-frequency oscillatory ventilation in adults with acute respiratory ventilation in adults with acute respiratory distress syndrome. Crit Care Med 2007; 35:1522. distress syndrome. Crit Care Med 2007; 35:1522.

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Salim, A, Martin, M. High-frequency percussive Salim, A, Martin, M. High-frequency percussive ventilation. Crit Care Med 2005; 33:S241. ventilation. Crit Care Med 2005; 33:S241.

Carlon, GC, Ray, C, Klain, M, et al. High-frequency Carlon, GC, Ray, C, Klain, M, et al. High-frequency positive pressure ventilation in management of a positive pressure ventilation in management of a patient with bronchopleural fistula. patient with bronchopleural fistula. Anesthesiology 1980; 52:160.Anesthesiology 1980; 52:160.

Bishop, MJ, Benson, MS, Sato, P, Pierson, DJ. Bishop, MJ, Benson, MS, Sato, P, Pierson, DJ. Comparison of high-frequency jet ventilation with Comparison of high-frequency jet ventilation with conventional mechanical ventilation for conventional mechanical ventilation for bronchopleural fistula. Anesth Analg 1987; bronchopleural fistula. Anesth Analg 1987; 66:833. 66:833.

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Eastman, A, Holland, D, Higgins, J, et al. High-Eastman, A, Holland, D, Higgins, J, et al. High-frequency percussive ventilation improves frequency percussive ventilation improves oxygenation in trauma patients with acute oxygenation in trauma patients with acute respiratory distress syndrome: a retrospective respiratory distress syndrome: a retrospective review. Am J Surg 2006; 192:191.review. Am J Surg 2006; 192:191.

Mehta, S, Granton, J, MacDonald, RJ, et al. High-Mehta, S, Granton, J, MacDonald, RJ, et al. High-frequency oscillatory ventilation in adults: the frequency oscillatory ventilation in adults: the Toronto experience. Chest 2004; 126:518. Toronto experience. Chest 2004; 126:518.

David, M, Weiler, N, Heinrichs, W, et al. High-David, M, Weiler, N, Heinrichs, W, et al. High-frequency oscillatory ventilation in adult acute frequency oscillatory ventilation in adult acute respiratory distress syndrome. Intensive Care respiratory distress syndrome. Intensive Care Med 2003; 29:1656. Med 2003; 29:1656.

Carlon, GC, Howland, WS, Ray, C, et al. High-Carlon, GC, Howland, WS, Ray, C, et al. High-frequency jet ventilation: A prospective frequency jet ventilation: A prospective randomized evaluation. Chest 1983; 84:551. randomized evaluation. Chest 1983; 84:551.

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Derdak, S, Mehta, S, Stewart, TE, et al. High-Derdak, S, Mehta, S, Stewart, TE, et al. High-frequency oscillatory ventilation for acute frequency oscillatory ventilation for acute respiratory distress syndrome in adults: a respiratory distress syndrome in adults: a randomized, controlled trial. Am J Respir Crit Care randomized, controlled trial. Am J Respir Crit Care Med 2002; 166:801. Med 2002; 166:801.

Bollen, CW, van Well, GT, Sherry, T, et al. High Bollen, CW, van Well, GT, Sherry, T, et al. High frequency oscillatory ventilation compared with frequency oscillatory ventilation compared with conventional mechanical ventilation in adult conventional mechanical ventilation in adult respiratory distress syndrome: a randomized respiratory distress syndrome: a randomized controlled trial [ISRCTN24242669]. Crit Care controlled trial [ISRCTN24242669]. Crit Care 2005; 9:R430. 2005; 9:R430.

Mentzelopoulos, SD, Roussos, C, Koutsoukou, A, Mentzelopoulos, SD, Roussos, C, Koutsoukou, A, et al. Acute effects of combined high-frequency et al. Acute effects of combined high-frequency oscillation and tracheal gas insufflation in severe oscillation and tracheal gas insufflation in severe acute respiratory distress syndrome. Crit Care acute respiratory distress syndrome. Crit Care Med 2007; 35:1500. Med 2007; 35:1500.

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Mehta, S, MacDonald, R, Hallett, DC, et al. Acute Mehta, S, MacDonald, R, Hallett, DC, et al. Acute oxygenation response to inhaled nitric oxide when oxygenation response to inhaled nitric oxide when combined with high-frequency oscillatory ventilation combined with high-frequency oscillatory ventilation in adults with acute respiratory distress syndrome. in adults with acute respiratory distress syndrome. Crit Care Med 2003; 31:383. Crit Care Med 2003; 31:383.

Ferguson, ND, Chiche, JD, Kacmarek, RM, et al. Ferguson, ND, Chiche, JD, Kacmarek, RM, et al. Combining high-frequency oscillatory ventilation Combining high-frequency oscillatory ventilation and recruitment maneuvers in adults with early and recruitment maneuvers in adults with early acute respiratory distress syndrome: the Treatment acute respiratory distress syndrome: the Treatment with Oscillation and an Open Lung Strategy (TOOLS) with Oscillation and an Open Lung Strategy (TOOLS) Trial pilot study. Crit Care Med 2005; 33:479. Trial pilot study. Crit Care Med 2005; 33:479.

Demory, D, Michelet, P, Arnal, JM, et al. High-Demory, D, Michelet, P, Arnal, JM, et al. High-frequency oscillatory ventilation following prone frequency oscillatory ventilation following prone positioning prevents a further impairment in positioning prevents a further impairment in oxygenation. Crit Care Med 2007; 35:106.oxygenation. Crit Care Med 2007; 35:106.

Bollen, CW, Uiterwaal, CS, van Vught, AJ. Bollen, CW, Uiterwaal, CS, van Vught, AJ. Systematic review of determinants of mortality in Systematic review of determinants of mortality in high frequency oscillatory ventilation in acute high frequency oscillatory ventilation in acute respiratory distress syndrome. Crit Care 2006; respiratory distress syndrome. Crit Care 2006; 10:R34. 10:R34.

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Fessler, HE, Hager, DN, Brower, RG. Feasibility of Fessler, HE, Hager, DN, Brower, RG. Feasibility of very high frequency ventilation in adults with very high frequency ventilation in adults with acute respiratory distress syndrome. Crit Care acute respiratory distress syndrome. Crit Care Med 2008; 36:1043. Med 2008; 36:1043.

Reper, P, Wibaux, O, Van Laeke, P, et al. High Reper, P, Wibaux, O, Van Laeke, P, et al. High frequency percussive ventilation and frequency percussive ventilation and conventional ventilation after smoke inhalation: a conventional ventilation after smoke inhalation: a randomised study. Burns 2002; 28:503. randomised study. Burns 2002; 28:503.

Hurst, JM, Branson, RD, DeHaven, CB. The role of Hurst, JM, Branson, RD, DeHaven, CB. The role of high-frequency ventilation in post-traumatic high-frequency ventilation in post-traumatic respiratory insufficiency. J Trauma 1987; 27:236. respiratory insufficiency. J Trauma 1987; 27:236.

Angus, DC, Lidsky, NM, Dotterweich, LM, et al. Angus, DC, Lidsky, NM, Dotterweich, LM, et al. The influence of high-frequency jet ventilation The influence of high-frequency jet ventilation with varying cardiac-cycle specific with varying cardiac-cycle specific synchronization on cardiac output in ARDS. Chest synchronization on cardiac output in ARDS. Chest 1997; 112:1600. 1997; 112:1600.