High Frequency Percussive Ventilation / AARC

American Association for Respiratory Care’s

, VA 22042

Natalie.Napolitano@inova.org

In This Issue…

Notes from the Editors Jenni L. Raake, RRT, and Natalie Napolitano, MPH,

RRT-NPS

High Frequency Percussive Ventilation in the Pediatric

ICU

Rita Giordano, RRT-NPS

Case Study 1: Application of High Frequency Percussive

Ventilation in a Patient with Radiation Pneumonitis as a

Maureen Ginda, BS, RRT-NPS

Lung Protective Strategy while Awaiting Lung

Transplant

Case Study 2: Application of High Frequency Percussive

Ventilation with Asthma

Cheryl Dominick, BS, RRT-NPS

Section Connection

Notes from the Editors

Jenni L. Raake, RRT, and Natalie Napolitano, MPH, RRT-NPS

This issue of the Bulletin is dedicated to a closer look at high frequency percussive ventilation

(HFPV), provided for us by three of our members from the Children’s Hospital of Philadelphia.

Rita Giordano kicks things off with an overview of HFPV, and Maureen Ginda and Cheryl

Dominick follow with interesting case studies on patients who were treated with HFPV in their

facility.

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High Frequency Percussive Ventilation in the

Pediatric ICU

Rita Giordano, RRT-NPS, Children’s Hospital of Philadelphia, Philadelphia, PA

What do you think of when you hear the words “high frequency”? To many of us who work in

respiratory care, high frequency means a type of mechanical ventilation that employs very

high respiratory rates (>150 breaths per minute) and small tidal volumes. The two types of

high frequency ventilators (HFV) most commonly utilized are the jet ventilator (HFJV, rate

100–600/minute) and the oscillatory ventilator (HFOV, rate 300–3000/minute). However,

there is a third type, and it is capable of providing high frequency ventilation to preterm

infants through adults.

Developed by Forrest Bird, MD, PhD, in the early 1980s, high frequency percussive ventilation

(HFPV) is provided by a pneumatically powered, time-cycled, pressure-regulated ventilator

that also delivers inspiratory and expiratory oscillations.1 It was approved for patient use by

the Food and Drug Administration in 1993. The HFPV Volume Diffusive Respirator (VDR-4®) is

engineered to provide oxygenation and carbon dioxide elimination using lung-protective

strategies.

The phasitron piston mechanism, which acts as the inspiratory and expiratory valve, is driven

by a high-pressure gas supply at a rate of 200–900 beats per minute.1 The VDR provides

percussive sub-tidal volumes at high rates that are stacked in a stepwise fashion and are

superimposed onto conventional convective pressure control type breaths.1 The lung volumes

are progressively increased during inspiration with sub-tidal volume delivery until an

oscillatory plateau is reached and maintained at end-inspiration. The lung emptying occurs

during an oscillating passive exhalation to a desired end-expiratory pressure.1

The intrapulmonary percussions at high frequencies that are inherent in HFPV provide for

mobilization of secretions and more uniformed intrapulmonary gas exchange with improved

distal ventilation.2 Each percussive breath is responsive to changes in compliance of the lung.

The I:E ratio is usually maintained at 1:1, resulting in oscillatory plateau. With HFPV, the

convective positive-pressure breaths are controlled breaths, with no assisted breaths available

to the patient. Spontaneous breathing can be accomplished through a demand valve system

and is available throughout the breathing cycle.

The main differences between the high frequency machines are: mean airway pressures can

fluctuate with the HFPV and HFJV, whereas with the HFOV, mean airway pressures are held

constant under optimal conditions. Exhalation using the HFPV and HFJV is passive while with

the HFOV it is active. Weaning and liberation from the VDR-4 ventilator can be accomplished

through the continuous demand flow system.

Although documented evidence is limited, some have found that HFPV should be considered as

an option for patients with smoke inhalation injury and ARDS. Cioffe et al. published a case

series of 54 adult burn patients with inhalation injury who were prophylactically placed on the

VDR upon admission.3 They found a significantly lower rate of pneumonia and mortality in the

group treated with HFPV.

Reper et al. did a randomized trial of 35 adult patients with inhalation injury who were on

HFPV and conventional ventilation (CV), comparing gas exchange, lung injury, and

hemodynamics.4 The HFPV group showed a significant improvement in P/F ratio in the first 72

hours of use, with no difference in the hemodynamic status or clinical evidence of barotraumas

between the two groups.

Fifty-four adult trauma patients with post-injury ARDS and refractory hypoxemia who were

studied by Hurst et al. showed improvement in oxygenation with HFPV, with a decrease in

peak airway pressures without significant barotrauma.5 Hurst et al. also took a look at 100

adults with acute respiratory failure who were randomized to CV or HFPV.6 The defined

endpoints were P/F ratio and intrapulmonary shunt fraction. No difference was seen between

the time it took to reach these endpoints. However, the investigators did note significantly

lower airway pressures for the ARDS patients on HFPV throughout the study period.

Velmahos et al. reported a case series of 32 adult medical and surgical ARDS patients with

consistent case exchange failure on CV that was transitioned to HFPV.7 After transition to

HFPV, P/F ratio and PIP improved within one hour, with sustained improvement throughout

the study period.

Recent studies in the pediatric population have been in the burn and inhalation injury

population. Mlcak et al. performed a randomized, prospective trial of 43 children with

inhalation injury, randomizing them to CV or HFPV.8 The HFPV group maintained adequate

ventilation with lower PIPs, with a trend towards lower mortality and incidence of ventilator

associated pneumonia.

Carmen et al. also evaluated smoke injury patients, taking a prospective look at 64 patients

with ARF who were randomized to CV or HFPV.9 The CV group utilized low tidal volume

ventilation with 6-8 cc/kg. The results showed significant improvement in oxygenation and PIP

in the HFPV group.

At the Children’s Hospital of Philadelphia, we have utilized the VDR-4 on patients with

burn/smoke injury, ARDS with secretion clearance issues, and bronchiolitis. We have also used

it as a lung protection and recruitment strategy. With the VDR-4 HFPV we have been

successful in improving ventilation and oxygenation, and providing lung recruitment and

secretion removal, while maintaining patients at a lower airway pressure compared to

conventional ventilation.

References

1. Salim A, Martin M. High-frequency percussive ventilation. Crit Care Med

2005;33(Suppl):S241-S245.

2. Freitag L, Long WM, Kim CS, et al. Removal of excessive bronchial secretions by

asymmetric high-frequency oscillations. J Appl Physiol 1989;67:614-619.

3. Cioffi WG, Rue LW, Graves TA, et al. Prophylactic use of high-frequency percussive

ventilation in patients with inhalation injury. Ann Surg 1991;213:575-582.

4. Reper P, Wibaux O, Van Laeke D, et al. High frequency percussive ventilation and

conventional ventilation after smoke inhalation: A randomized study. Burns

2001;28:503-508.

5. Hurst JM, Branson RD, DeHaven CB. The role of high-frequency ventilation in posttraumatic

respiratory insufficiency. J Trauma 1987;27:236-242.

6. Hurst JM, Branson RD, Davis L, et al. Comparison of conventional mechanical

ventilation and high frequency ventilation. Ann Surg 1990;211:486-491.

7. Velmahos GC, Chan LS, Tatevossian R, et al. High-frequency percussive ventilation

improves oxygenation in patients with ARDS. Chest 1999;116:440-446.

8. Mlcak RP, Suman OE, Sanford AP, et al. Comparison of high frequency percussive

ventilation in pediatric patients with inhalation injury. J Burns Surg Wound Care (serial

online) 2002;1:19.

9. Carmen B, Cahill T, Warden G, et al. A prospective, randomized comparison of volume

diffusive respirator vs conventional ventilation for ventilation of burned children. J

Burn Care Rehabil 2002;23:444-448.

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Case Study 1: Application of High Frequency

Percussive Ventilation in a Patient with

Radiation Pneumonitis as a Lung Protective

Strategy while Awaiting Lung Transplant

Maureen Ginda, BS, RRT-NPS, Children’s Hospital of Philadelphia, Respiratory Care

Department, Philadelphia, PA

Introduction: The case describes the use of HFPV as a lung protective strategy to treat and

prevent additional air leak syndrome.

Case: A six-year-old patient with neuroblastoma was diagnosed at 20 months of age and

underwent a course of treatment that included resection of the tumor, chemotherapy,

radiation, and stem cell transplant. At five years of age the child was found to have radiation

pneumonitis and shortly thereafter was listed for lung transplantation. The patient presented

to the emergency department with a right sided pneumothorax for which a chest tube was

placed. Hours later the child was admitted to the general care area on high flow nasal cannula

for six weeks.

Respiratory failure continued despite maximal medical therapies, including noninvasive bi-level

ventilation, antibiotics, high dose steroids, and bronchodilators. The progression of the disease

process led to transfer to the ICU, where inotropic infusions were started. Due to poor carbon

dioxide clearance, the patient was subsequently intubated and placed on HFPV via the VDR-4

ventilator.

MODE PIP/PEEP RATE Mean airway

pressure

ph PaCO2 PaO2

SIMV PC 50/8 35 24 7.0-7.16 100-130 >100 on 50%

HFPV* 42/7 20/550 23 7.3-7.4 70-80 >100 on 40%

*weaned off epinephrine and dopamine infusions within 24 hours of HFPV starting

After five days of HFPV the patient’s pulmonary status improved and the ventilation strategy

was transitioned to pressure control SIMV with the intent of beginning a pulmonary

rehabilitation program in preparation for transplantation. Within 36 hours bilateral

pneumothoraces and pneumomediastium developed. The patient was again treated with

bilateral chest tubes and placed back on HFPV.

MODE PIP/PEEP RATE Mean airway

pressure

pH PaCO2 PaO2

SIMV PC 52/8 60 25 7.4 80’s 90 on 50%

HFPV 35/7 25/500 18 7.4 80’s 90’s on 50%

Within 24 hours all air leaks were resolved. The patient remained on these settings for 18

days, with no further air leaks.

Due to an anticipated long wait for lungs, along with the patient’s inability to participate in

rehabilitation and worsening multisystem organ failure, the patient was deactivated from the

active transplant list. One day later support was withdrawn at the family’s request.

Discussion: Although this case did not have a positive outcome, the therapeutic use of the

VDR-4 HFPV accomplished our goals of maintaining acceptable pH while treating and

preventing additional barotrauma.

BILATERAL AIR LEAK ON SIMV/PC

AFTER 36 HOURS OF HFPV

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Case Study 2: Application of High Frequency

Percussive Ventilation with Asthma

Cheryl Dominick, BS, RRT-NPS, Children’s Hospital of Philadelphia, Respiratory Care

Department, Philadelphia, PA

Introduction: The case describes the application of HFPV for lung recruitment, secretion

mobilization, and ventilation in a patient with severe asthma.

Case: A seven-year-old male presented to an outside hospital limp and cyanotic with initial

SpO2 of 80%. He was stabilized on ventilator settings and transferred to Children’s Hospital of

Philadelphia. On arrival to the PICU, he was placed on SIMV with a RR of 24, tidal volume of

200, Peep of 6, and pressure support of 10 with 40% FiO2. He was started on Q1H

bronchodilators and epinephrine for hypotension, and was paralyzed in order to control

ventilation.

The patient was weaned from vent support, transitioned to Q4H bronchodilators, and

extubated to a nasal cannula on hospital day three. The patient had been extubated for 48

hours when he began having acute and severe desaturations to the high 60s. Due to his

hypoxemia, he was reintubated. Despite conventional ventilation and prone positioning, he

continued to be hypoxemic with saturations in the 70s to low 80s. Nitric oxide was started

with no improvement.

On chest x-ray his ETT was in good position, his right lung was hyper-inflated, and he had

complete lung collapse on the left with shift of the mediastinal structures. Bronchoscopy by

ENT demonstrated copious secretions in the branches of the left bronchi. However, no mucus

plug was noted. Some secretions, but not all, were able to be removed via bronchoscopy.

Saturations increased to 90% with aggressive hand-ventilation.

Immediately following the bronchoscopy the decision was made to place the patient on HFPV.

Over a period of three hours we saw significant improvement in his saturations and were able

to wean his oxygen supplementation from 100% to 30%; he was off nitric oxide within eight

hours. The patient remained on HFPV for two days and was successfully extubated to a nasal

cannula the next day (hospital day seven).

VDR settings were as follows:

FIO2/NO Conv Rate Perc Rate PIP Peep MAP

Initial 100/20 20 600 35 6 20

1 hour 70/20 15 600 30 6

Not

written

3 hours 30/10 15 650 20 6 12

Discussion: Many strategies are used for secretion mobilization in patients with respiratory

failure. HFPV combines the benefits of high frequency ventilation and conventional bulk flow

gas exchange, resulting in effective secretion mobilization. We report the successful use of

HFPV for secretion mobilization in severe asthma.

 

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