Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Interventions 3 > High Frequency Ventilation > Flashcards

High Frequency Ventilation Flashcards

1
Q

What Is High Frequency Ventilation (HFV)

A

A form of mechanical ventilation that uses frequencies that are greater than 150 bpm and small tidal volume

Often the tidal volumes will be smaller than deadspace

Deadspace estimated to be 2.2 mg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Frequencies in HFV

A

Frequencies is specified in Hertz (Hz) which is cycles per second

1 Hz=1 cycle/sec=1 breath per second=60 bpm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What Are the Indications for HFV

A

Acute Lung Injury (Severe Oxygenation Failure)

Ventilation failure

Upper airway surgery and bronchoscopy

BP Fistula or pulmonary air leaks in neonates (eg. PIE)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Indications for HFV-Acute Lung Injury

A
  • Adult: No evidence that HFV is better than conventional CHR P&P
    • When OI >20 on two ABG that are 6h apart
  • Neonates:HFV is considered superior to conventional ventilation, however when surfactant lung protective strategies and NO is used there does not seem to be a benefit to HFV over conventional
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Indications for HFV-Ventilation Failure

A

Ph <7.25 with Vt <6 mL/kg and plateu pressure <30 cmH2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Indications for HFV-Upper Airway Surgery and Bronchoscopy

A

HFJV preferred over conventional ventilation as they provide more efficient gas exchange with an open airway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Indications for HFV-BP Fistula or pulmonary air leaks in neonates (eg. PIE)

A

HFJV is most used traditionally (less bulk flow= less movement)

Air leak disease is usually the result of barotrauma where as volutrauma tends to form a ARDS picture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

High Frequency Positive Pressure Ventilation (HFPPV)

A

Modified form of conventional ventilation

Uses a conventional ventilator high a high RR (120-240 bpm) and a low Vt (3-5 ml/kg)

Used before HFJV/HFO were readily available to be used so it is not used much now

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

High Frequency Flow Interrupter (HFFI)

A

Uses a ball that moves at a set frequency to interrupt the flow to the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

High Frequency Percussive Ventilation (HFPV)

A

Combines HFV and conventional ventilation

Superimposes oscillations on the conventional ventilation

The percussive vibrations are thought to aid in secretion mobilization.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

High Frequency Jet Ventilation (HFJV)

A

Passive exhalation

When expiration is passive there is the risk of breath stacking

Combines the use of a jet ventilator and a conventional ventilator

The conventional vent provides the PEEP (which = MAP) and +/- sigh breaths

The jet vent pulses above this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

High Frequency Oscillation (HFO)

A

Most commonly used

Only type of HFV that uses active exhalation

Active Exhalation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

High Frequency Jet Ventilation (HFJV) Methods of Administration

A

Using a specially designed ETT (eg. Hi-Lo Jet ETT)

Using a specially designed ETT connector (no re-intubation required) and the Jet Ventilator in addition to the conventional vent

Via a trans-tracheal catheter

A crude form; usually present in difficult airway carts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How Does HFJV Work

A

Uses 14-18 gauge small bore injector in which gas is introduced at high pressure (15-50 psi). Gas leaves from a different route. Gas flow interrupted by pneumatic, fluidic or electronically controlled solenoid valves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Jet Ventilation ETT

A

Central Lumen for the conventional ventilator

Pressure monitor which opens below the cuff

Another lumen which delivers the jet ventilation and open above the cuff

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

High Frquency Osillation Main Controls

A

FiO2

MAP

Amplitude

Frequency

TI% or I:E

Bias Flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Indications in Neonates for HFJV

A
  • A HFJV for infants
  • Indications for use:
  • RDS
  • Rescue infants with lung injury e.g. PIE
  • Others:
    • Air leak for reasons other than PIE
    • Meconium aspiration
    • Pneumonia
    • CDH
    • PPHN
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Basic Theory of Jet Ventilation

A

VT ~ 1 ml/kg = half the size of anatomic dead space

High velocity inspiration – moves through deadspace gas instead of pushing dead space ahead of fresh gas

Exhaled gas cycles out in a counter-current helical flow pattern around incoming gas which helps with clearance of secretions from the airway

PIP settings may compare to conventional but inspirations are short and fast therefore pressure falls quickly meaning alveolar pressures much lower than peak airway pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Bunnell LifePulse

A

Jet Ventilation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does the conventional ventilator work with jet ventilation

A

The conventional ventilator is responsible for

Background conventional ventilation

Entrainment of gas

Maintenance of PEEP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

HFJV-Ventilation

A

Amplitude produces VT and controls PaCO2

Frequency (in Hz)

Exhalation is passive; PEEP is constant if rate low enough to prevent air trapping

NOTE: when Ti is constant changes in the frequency do not impact VT (and thus, an increased rate will decrease PaCO2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

HFJV-Oxygenation

A

FiO2 (on the conv. vent)

PEEP = MAP

PEEP is the primary controller for MAP and oxygenation

Find optimal MAP by raising PEEP 1-2 cmH2O above conventional settings – stablize patient using CMV of 5bpm and FiO2 getting stable SaO2 and then switching to CPAP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

High Frquency Osillation How It Works

A

Requires specialized machines to provide HFO

Basically uses a bias flow past the airway and either a piston, high frequency speaker (diaphragm) or rotating valve to provide the oscillations

24
Q

High Frquency Osillation How It Differs from other HFV Techniques

A

Expiration is active

Gas flow is sinusoidal

Means it flow in and out in a repeatable manner

Bulk flow rather than jet pulsations are delivered

25
Q

Minute Ventilation Equation in HFOV

A

ṾE = f x VT2VT: 0.8 to 2.0 ml/kg (less than deadspace!!)

Still results in effective CO2 elimination due to the gas transport mechanisms involved in HFV

The tidal volume is the bigger factor in the MV!

26
Q

Proposed Mechanisms of Gas Exchange

A

Bulk Convection

2.Pendelluft gas movement

Gas moving from one lung unit to another due to differences in R and C

3.Asymmetric velocity profiles (Streaming)

Gas in the center moves faster than gas at periphery

Also bi-directional gas movement (at the center O2 moves into the lungs while at the periphery CO2 moves out)

4.Taylor dispersion

High velocity gas movement enhances the development of turbulence in the conducting airways

This movement encourages dispersion of gas, both laterally and centrally

5.Cardiogenic oscillation

The oscillations of the circulatory system assist gas movement, especially at high frequencies

27
Q

3100: Theory of Operation

A
28
Q

HFOV Oxygenation

A
  • The MAP is used to inflate the lung and optimize the alveolar surface area for gas exchange
  • MAP = Lung Volume (FRC)
  • Controls Affecting Oxygenation are:
    • FiO2
    • MAP
    • (TI%)
29
Q

Alveolar Ventilation in HFV and CV

A

Alveolar ventilation during conventional ventilation is defined as: f x VT

Alveolar ventilation during HFV is defined as: f x VT2

Therefore, changes in volume delivery have the most significant affect on CO2 elimination in HFV

30
Q

HFV and Ventilation

A

CO2 removal is affected by 3 main controls:

Frequency (Hz): DecreaseFrequency s volume (and MV!!)

Amplitude (Delta P): Amplitude s volume

(TI%): Insp. Time s volume

When you are adjusting for CO2 consider changing your amplitude first in babies and for adulst you should consider changing the freuqncy first

31
Q

What are same less common ways to remove CO2 with HFV

A

Max bias flow, deflate cuff.

32
Q

HFOV and Frequency

A

to decrease PaCO2 you would decrease frequency!! This allows for a larger VT which is the bigger part of the MV=f x VT2

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

33
Q

What is your first and second choice in HFOV for Decrease PaCO2

A

1) Frequency
2) Amplitude which is produced by the power setting

Note: As the MAP is increased there is less DP available, B/c the higher the MAP the more resistance the piston has to work against.

34
Q

% Inspiratory Time Effect on CO2

A

▪Effect on CO2:

▪Increased % Insp Time allows more time for piston movement and \ can assist with CO2elimination

▪Effect on O2:

▪Increased % Insp Time increases delivered MAP \ can improve oxygenation

35
Q

3100: Piston Centering

A

3100B: Piston Centering is automatically regulated by the instrument and requires no operator intervention.

3100A: This is adjusted by the operator!

36
Q

3100: Starting Up

A

To pressurize the patient circuit, the Reset / Power Fail button must be pressed and helduntil the mean airway pressure builds up and then

The Start / Stop button is used to start and stop the oscillator.

The oscillator may be stopped without a complete loss of mean airway pressure.

37
Q

3100: Preset Alarms

A

Upon activation the oscillator will stop, the dump valve opens and the circuit vents to ambient

Bias flow is still delivered when the MAP<5 cmH2O is activated.

38
Q

3100: Source Gas Low

A

The source gas low alarm will provide only a visual indicator if either of the high pressure gas supplying the blender falls below 30 psig OR if the source gas feeding the piston cooling system falls below 30 psig.

39
Q

3100: Battery Low

A

The battery low alarm will provide only a visual indicator when the nine volt alarm battery needs replacement

This battery is used to power the Power Fail alarm NOTthe oscillator.

40
Q

3100: Oscillator Overheated

A

Failure to correct the situation will result in piston failure!

The oscillator overheated alarm will provide only a visual indicator if the linear motor temperature exceeds 150°C

Under N operating conditions and with a dedicated air line to cool piston this should not occur.

41
Q

3100: Oscillator Stopped

A

The oscillator stopped alarm will provide audible and visual indicators if the oscillatory amplitude is at or below 7 cmH2O and the oscillatory subsystem is energized.

(as indicated by the illumination of the green LED on the start stop button)

42
Q

Adjusting the Parameters of HFOV in Adults

Oxygenation

A

FiO2is primary control to adjust, if at 100% then increase Paw by 3-5 cmH2O

Wean Paw by 1-2 cmH2O Q4H until at 34 cmH2O; then wean FiO2

43
Q

Adjusting the Parameters of HFOV in Adults

Ventilation

A

▪Frequency is the primary control to adjust (increments of 1 Hz)

▪Goal ΔP is 90 cmH2O

▪Consider increasing bias flow up to 60 LPM

▪Consider inducing a slight ETT cuff leak

44
Q

When Making Changes

A

The controls can alter more than one parameter (indirectly) always double checkthat all other settings remained the same changes (and adjust if necessary)

. As MAP is increased the amplitude will decrease (for the same power setting)

45
Q

HFOV Returning to Conventional Ventilation

A

Patient stable for more than 12h withFIO2£0.40 and Paw £25 cmH2O

Patient tolerating (or at least recovering quickly from) interventions without prolonged desaturation events

46
Q

Typical Initial Settings (Neonate)

Bias Flow

A

Bias Flow = 12-15 LPM

47
Q

Typical Initial Settings (Neonate)

Frequency

A

Frequency = 8-15 Hz

Based on weight…smaller the baby the higher the Hz and vice versa

Higher frequencies used for air leak syndromes

48
Q

Typical Initial Settings (Neonate)

FIO2

A

FIO2= set 20% higher than current mechanical ventilation settings (may need to start at 100%)

49
Q

Typical Initial Settings (Neonate)

Power

A

Power = ΔP=~20 cmH2O to start= adjust to achieve appropriate wiggle

When weaning don’t typically go below a ΔP of 16 cmH2O)

50
Q

Typical Initial Settings (Neonate)

Paw

A

Paw = initially set 2 cmH2O > Paw on conventional vent

Lower Paw for air leak syndromes

51
Q

Typical Initial Settings (Neonate)

% I Time

A

% I Time = 33%

◦FIO2= set 20% higher than current mechanical ventilation settings (may need to start at 100%)

◦Paw = initially set 2 cmH2O > Paw on conventional vent

▪Lower Paw for air leak syndromes

◦Power = ΔP=~20 cmH2O to start= adjust to achieve appropriate wiggle

When weaning don’t typically go below a ΔP of 16 cmH2O)

52
Q

In Neonates (AHS) the primary controls for oxygenation and ventilation

A

Ventilation = ΔP (then f)

Oxygenation = MAP (then FiO2)

53
Q

HFOV Starting Up

A

The circuit must first be occluded and then pressurized to above the preset min MAP alarm before oscillations can begin

Ideally the ETT is clamped at end-inspiration on the conventional vent, the oscillator is connected, the circuit is pressurized (hold Reset/Power Failure), the clamp is released, then the Start/Stop button pressed to begin oscillations

This minimizes de-recruitment of the lung!

Always leave the conventional ventilator at the bedside and set up appropriately for the patient!

54
Q

HFOV Lung Inflation and Recruitment

A

Monitored at least daily via CXR

Adult: Should see posterior 9 to 11 thribs in both hemithoracesas an indicator of overallideal lung recruitment

Catheter-if tip left within circuit will dampen the effective delta P in lungs

LRM within 5-10 minutes of initiation (adults)

Disconnections

All efforts should be made to avoid disconnecting the patient

Eg.Use closed suction systems (*a note on these: ensure catheter tip fully removed!)

LRM should be performed after any disconnect – Adult

55
Q

HFOV Wiggle

A

This wiggle is the only indication that the airway is patent and ventilation is reaching the lungs

An RN/RT should always be at the bedside

If the wiggle diminishes or is absent this is indicative of a partial/full airway obstruction!

The oscillator Will Not Alarm in the Event of an Airway Obstruction!

This wiggle action may cause the ETT to be wiggled out!

Repositioning/re-securing of the airway needs to be done often

56
Q

Oscillator Circuits

A

These are made of a low compliance material to minimize the compressible volume of the circuit

◦Heated humidity always used

▪Use auto-fill pots to maintain constant compressible volume and temperatures

▪Due the high levels of bias flow through the circuit the water is used quickly!

▪Pressure bags around the water used to prevent inflation of bag

◦There is a water trap positioned below the diaphragm

Always leave a small amount of water in to act as a seal

57
Q

Oscillator Circuits and HME

A

Can not use HME B/C VT’s are < VDHME’s are ineffective

Interventions 3 (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions