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HFPV VDR4 ®

Definition:

“The VDR® is classified as a pneumatically powered, pressure regulated, time cycled,

high frequency flow interrupter.”

- Delivers high frequency in a range of 200-900 cycles/min.

- Passive exhalation

Adel Bougatef MD, PhD.

 

Inspiration (I) Expiration (E)

Pressure

Time (sec)

ei

OD.CPAP

- I / E ratio : conventional rate expressed in seconds.- i / e ratio : high frequency rate expressed in milliseconds.  

Plateau equilibrium

Step inflation lung 

Typicale HFPV waveformTypicale HFPV waveform

Inspiratory Time

Pulsatile Flowrate(PIP)

Osc./Demand CPAP

Expiratory Time

Pulse FrequencyPulse i:e Ratio

Conv.PressureRise

HFPV VDR4 : SET-UP

IT = 2.8 sec ET = 1.8 sec (for Low Frequency = 12 - 14 cycles/min)

HF = 500’/mini/e = 1 / 1 to 1/2

PIP = 40 cm H2O

Oscillatory CPAP = 10 -14 cm H2O

FiO2 : 1 (and according to BGA)

Demande CPAP/PEEP = O !*I E

i e

PIP

• DEMAND CPAP– 2 cmH2O for spontaneously breathing

patients

– 0 cmH2O for non-spontaneously breathing patients.

*

CO2 Washout• i/e (1/3 - 1/5)

• HF ( 300 - 500 cycles/min)

• ET to Low frequency (12-18 cycles/min) but hold sufficient IT for gas exchange.

• Osc.CPAP

• Progressive PIP by level of 2-3 cmH2O

• Convective Pressure rise.

Oxygenation• i/e (1/1)

• HF ( 500 - 700 cycles/min)

• IT , ET will be adjusted for I/E =1.5/1

• FIO2

• Osc. CPAP

• Convective Pressure rise.

• Progressive PIP by level of 2-3 cmH2O

• Convective Pressure rise.

VDR SET UP

FIO2: SPO2 ≥ 95 %

I Time: 2.8 seconds

E Time: 1.8 seconds

Low rate: ≈ 13 cycles/min

Pulse Frequency: ≈ 500 (with i/e: 1/2)

Pulsatile Flowrate: 35 - 45 cm H2O

Oscillatory cpap: 10 cm H2O

ARDSARDS

PIP/PEEP/FIO2 To keep: Ph ≥ 7.30, SpO2 ≥ 95%, PaCO2 ≈

25-45 mm Hg

Obtain: Chest XRay, ABG, Within 4

hours of VDR set Up

If: SPO2 < 95 or PaO2 < 60 mmHg

1. Pulsatile Flowrate 2 cm H2O increment. 2. Add Convective Pressure Rise. 3. Oscillatory Cpap. 4. ,, Inspiratory Time. 5. ,, FIO2.

If:

ETCO2 > 40 mm Hg PaCO2 ≥ 45 mm Hg

1. Pulsatile Flowrate 2 cm H2O increment. 2. Inspiratory Time 0.1 second increment. 3. Reduce Pulse Frequency ( i/e: 1/2 to 1/3). 4. ,, ,, ,, Oscillatory Cpap. 5. Add Convective Pressure Rise. 6. Assess for airway obstruction.

If: ETCO2 ≤ 25mm Hg

PaCO2 ≤ 25 mmHg

1. Pulsatile Flowrate 2 cm H2O increment. 2. Expiratory Time. 3. Pulse Frequency ( i/e: 1/1). 4. Oscillatory Cpap if SPO2 ≥ 95 %.

If SPO2 ≥ 98 % then: Reduce FIO2 10 % increment (30% lower limit). Reduce PEEP by 2 cm H2O increment. Don’t Reduce PEEP ≤ 8 cm H2O. Reduce Pulsatile flowrate by 2 cm H2O increment. Don’t reduce to < 10 cm H2O difference PIP/PEEP.

Concider Extubation when: FIO2 ≤ 30 %. Pulsatile Flowrate < 35 cm H2O. PEEP < 10 cm H2O, P/F > 250. Chest X-Ray with minimal infiltrates. Patient stable for 24-48 hours.

Transition To N.I.V To reduce W.O.B. Concider Periodic IPV

Yes

Yes

Yes