practical aspects for the clinical use of pulmovista...

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Practical Aspects for the Clinical use of PulmoVista 500

Table of contents

1 The electrode belt ─ Size selection and application

2 Positioning the electrode belt

3 System setup ─ Filter settings

4 Defining the Regions of Interest

5 Effect of alternating pressure air mattresses on EELI

Practical aspects for the clinical use of PulmoVista 500 2 | 41

1. The electrode belt ─ Size selection and application


Lift the patient

Roll the patient

2. How to apply?

Use the measuring tape

Measure from mid axilla to mid axilla

In the transition zones go for the bigger

belt size

1. Which belt size?


- Firstly, put the bed to a 45° - 80° position

- Lift the patient’s head and put the mid

position of the belt to the cervical spine

- Then, lift the upper body a bit to move

the belt downwards to ICS 5

- Ensure, that the mid position is located

on the spine

- Close the belt

How to apply? Procedure 1



- Lift the upper part of the patient with two

persons

- Pass the belt under the patient

- Ensure, that the mid position is located

on the spine

- Close the belt




- Turn the patient onto his side

- Put one half of the belt into proper

position (i.e., where the belt is supposed

to be located on the patient)

- Put the other half cranial into a central

position

- Roll the patient on the other side

- Grab the half in central position and

arrange the belt accordingly

- Turn the patient back into supine position

and close the belt





Skin develops humidity and generates good

skin ─ electrode contact typically over the

first 5 minutes

Use water or ECG gel to establish a proper

contact right away

How to generate good skin-electrode contact ?

Perfect closing position would be closure

position no. 3

Do not close the belt too tight - just tight

enough to establish a sufficient contact

between the electrodes and the skin

Regularly observe skin condition

How tight?


8 | 41

Place it ideally on the upper abdomen

ECG electrodes from different manufacturers

work better or worse ─ check the contact on

the Signal check page

If contact is insufficient, put electrode gel or

water on the center of the contact

5. Where to place the reference electrode?

Practical aspects for the clinical use of PulmoVista 500


Typical pattern of initial electrode resistance (without ECG gel)

9 | 41



Typical pattern of electrode resistance after five minutes

10 | 41



Steady state electrode resistance after ten minutes

11 | 41


Practical example 1 – Live measurement

12 | 41 Practical aspects for the clinical use of PulmoVista 500

1. Select proper belt size

2. Attach the belt to the volunteer leaning on the backrest

3. Attach the ECG reference electrode

4. Check the electrode resistance

According to the Instructions for Use: ICS 4–6 (mid-clavicular line)

2. Positioning the electrode belt

13 | 41

3D EIT ─ AP projection

L

Apical part of the lung

cannot be captured by EIT

ICS 4

ICS 6


In contrast to CT scan, EIT captures a lense-

shaped volume


14 | 41

which represents a large part of the chest

whose impedance changes contribute to

the generation of EIT images


Why is relevant to have the electrode belt

placed in the right position?

15 | 41

If the belt is placed very high (directly under the armpits):

The mediastinum might not be located within the

electrode plane

You might not be able to clearly distinguish between left

and right lung

Basal lung regions mostly affected by recruitment/

de-recruitment might not be located within the electrode

plane

If the belt is placed “too low” (in a male, about 2 cm, or

more below the nipples, and in some females, below the

breasts):

Tidal images might display a mixture of diaphragmatic

movement and ventilation (making it impossible to

interpret the images)

During PEEP changes, the effects caused by diaphrag-

matic movement are getting stronger at lower PEEP

levels, making it hard to compare different PEEP levels

with the trend pages


Anatomy is not familiar with “standards” …

16 | 41

ICS 6



17 | 41

When positioning the belt, consider conditions

that may cause an elevated diaphragmatic

position:

Obesity

Intubated patients with low PEEP settings

Diaphragmatic paralysis (e.g., in sedated

patients)

Abdominal sepsis (high IAP)

Other conditions causing expansion of the

abdomen (e.g. tumor)

In such cases, it is recommended to place the belt at ICS 5 rather than ICS 6.

In female patients, put the belt on the breast rather than directly under the breast.


TV/VT ratio: 5.37 Pos. 10: ICS 4 TV 3785; VT 705


Effect of belt position on Tidal images: ICS 4


TV/VT ratio: 2.19


Effect of diaphragmatic position on Tidal images

21 | 41

Diaphragmatic position TV 1642; VT 750


TV/VT ratio: 1.36


Effect of abdominal position on Tidal images

22 | 41

Abdominal position TV 1001; VT 735


Effects of the belt position

23 | 41


L01

L17

Verifying the right belt position on the Main view

The new button “Enhance contrast”…


While keeping this button pressed, both positive and

negative (= phase-inverted) impedance changes are

enhanced, which makes it easier to detect

• diaphragmatic artefacts due to wrong belt position

• cardiac artefacts at the position of the heart

• aortic artefacts at the aorta (can be observed

occasionally)

• artefacts caused by fluid accumulations

(e.g., pleural effusion, lung empyema, hemothorax)

Normal color scaling Enhanced color scaling

PulmoVista 500 SW 1.20

Origin of phase-inverted impedance changes

PulmoVista 500 SW 1.20 | Product Training | September 2017 25 | 51

Pleural effusion

Heart/Mediastinum Aorta (?)

Diaphragma (= Belt too low)



1. But the belt down in steps of 2 cm, check for diaphragmatic artefacts

using the “Enhance contrast” button

2. Determine the position, where diaphragmatic movement becomes

obvious in the Tidal images

3. System setup ─ Filter settings

27 | 41

You get

what you set


Resp. Rate

Heart Rate


Filtering “off”

28 | 41



Filtering “low pass (35)”

29 | 41



Filtering “band pass (70–150)”

30 | 41



Filtering “band pass (70–150)”

31 | 41

Load 01HealthyLung.eit

Filter settings off first


6. Impact of cardiac pacing on EIT

Minor artifacts, no low-pass filtering

32 | 41



Minor artifacts, with low-pass filtering (60 1/min.)

33 | 41



Major artifacts, no low-pass filtering


Baseline is set to an artefact (as default definition sets baseline to minimum value…)


Major artifacts, with low-pass filtering (50 [1/min] )


Baseline is set to an artefact (as baseline is always defined for unfiltered data)


Major artifacts, with artefact filter turned on, no low-pass filter!


Artefact completely eliminates short-term artefacts (Baseline is always correctly defined at the end of expiration


New artefact filter (SW 1.12) eliminates short term spikes




1. View the unfiltered data

2. Turn on BandPass filter and determine the heart rate

3. Turn on LowPass filter and set it above the heart rate

4. Set the LowPass filter below the heart rate

5. Load the simulation file “Pacemaker”, (Artefact filter turned off),

observe the artefacts… Turn on the Artefact filter

Right Left

4. Defining the Regions of Interest

Distribution of ventilation in the healthy lung of a slim subject

39 | 41

ROIs set to quadrants (to assess unilateral effects):

Slightly more ventilation occurs in the right lung (ROI 1 and 3).

Expect about 50–55% in the right, 45–50% in the left lung

The upper (ROI 1 and 2) to lower lung ratio is about

50–50%, depending on the anatomy, the body position and the

belt position

Each quadrant has typically 25 ±5%

ROIs set to layers (to assess gravity dependent effects):

Mid-ventral/mid-dorsal is usually greater than ventral/

dorsal

Expect about 10 to 15% in ventral/dorsal regions

Note: In contrast to ROI arrangement as Quadrants, the height

of the ROI as Layers always affects the distribution of ventilation

Upper lung

Lower lung

1 2

3 4

Ventral

Mid-ventral

Mid-dorsal

Dorsal


4. Defining the Regions of Interest

In subjects with lung pathologies in dorsal regions

40 | 41

The issue: In contrast to CT scans, the location of the

ribcage is not displayed in EIT images:

Use the simplified assumption, that the distance of the

body surface to the ribcage is equal in the ventral and

dorsal part:

– Then, the ventral borderline can be used as a guide

to adjust the size of the ROIs

– Verify by Tidal images and ventilator settings, that

the lungs are not subject to overdistension

– If the size of the ROIs is reduced, check if the

sum of the 4 regional TVs is close to 100 %


Practical example 4 – Adjusting Regions of Interest (ROIs)


1. Load the simulation file “Healthy_Lung_obese”, with standard

ROI settings

2. Start measurements

3. Set ROI to Quadrants and assess ventilation distribution

4. Set ROI to Layers and assess ventilation distribution

5. Adjust size of ROIs to achieve normal ventilation distribution

5. The “Mattress-Effect”

42 | 41

This leads periodically to an improved skin-

electrode contact and lower resistances

between skin and dorsal electrodes

Self inflating and deflating air mattresses create specific artetacts in EIT data.

The periodical inflating and deflating increases and decreases the pressure on the electrodes in the

dorsal regions and changes the electrode position.

Pressure



43 | 41



44 | 41



45 | 41

Offline analysis revealed the

characteristic pattern of the

inflatable mattresses

Effects can only be observed in

the dorsal/mid-dorsal areas



46 | 41

Conclusions

Be aware of such effects when using

inflatable air mattresses

By knowing the effect the use of the dEELI-

trend is not feasible due to the strong effects

on the EELI

The distribution of ventilation can still be

evaluated

If dEELI is of importance, the inflation/

deflation function should be switched off

during the period of EIT monitoring


Practical example 5 – Assessing EIT data in the presence

of mattress artefacts…


1. Load the simulation files of the folder “21 Mattress effect” Start

measurements

2. Go to the End-insp. trend view to assess ventilation distribution

3. Go to the dEELI trend view to assess changes in end-expiratory

lung impedance

Thank you for

your attention.

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