Interpreting Curves and ResultsPeriFlux 6000 | peripheral pressure made intelligent

44-00316-01

Disclaimer

The information contained in this document is intended to provide general

information only. It is not intended to be, nor does it constitute, medical advice.

Under no circumstances is the information contained in this document to be

interpreted as a recommendation for a particular treatment for specific

individuals. In all cases it is recommended that clinicians perform their own

interpretations of data in conjunction with the clinical assessment of their patient.

Due to Perimed’s commitment to continuous improvement of our products, all

specifications are subject to change without notice.

All information and content in this document is protected by copyright. All rights

are reserved. Users are prohibited from modifying, copying, distributing,

transmitting, displaying, publishing, selling, licensing, creating derivative works,

or using any information available in or through the document for commercial or

public purposes. All responsibility for any liability, loss or risk, personal or

otherwise, which is incurred as a consequence, directly or indirectly, of the use

and application of any of the material in this document is specifically disclaimed.

• Diagnosing Peripheral Arterial Disease

(PAD), Critical Limb Ischemia (CLI) and Non-

healing Wounds

• Hands on, Tips and Tricks

• Interpreting Curves and Results

• Maintenance and Calibration

Introduction

The aim of this document is to provide an

understanding for the interpretation of the curves

generated during pressure measurements.

All curves are not as perfect as this one …

Look for a Change in Perfusion

• Baseline perfusion > 20 PU

• Use local heating feature

• Hold pressure until the pulsatile signal disappears

Pressure (mmHg)

Note that healthy controls can have

a “high” occluded perfusion even

though the vessels are closed. It is

important is observe a clear

change in perfusion.

• Good occlusion PU < 20.

• Clear difference between

occluded vessels and return of

flow.

Pe

rfu

sio

n (

PU

)

Arm

Ankle

∆

∆

∆

∆

Recording without heat

∆ low change

Pressure (mmHg) Pressure (mmHg)

Perf

usio

n (

PU

)

Perf

usio

n (

PU

)

Recording with heat

∆ big change

Local heat in laser Doppler probes:

• Increase the signal

• Facilitate interpretation

• Standardize measurements

Graphs recorded on the same patient without and with local heating.

Standardize Measurements with Heat

0

100

50

0

100

50

Thermostatic probe 457 on toe.

• Calcified vessels are stiff and difficult to occlude

• Common in diabetics, renal patients and

patients with critical limb ischemia

Incompressible Arteries

Normal patient – ankle pressure 105 mmHg

Pressure (mmHg)

Pe

rfu

sio

n (

PU

)

Diabetic patient with calcified arteries

Pressure (mmHg)

Pe

rfu

sio

n (

PU

)

Arterial calcification

Falsely elevated ABI

ABI > 1.4

Falsely elevated

ankle pressures

Underestimation

of PAD / CLI

Clear pulsations at occlusion pressure

Occlusion

Measure the Toe Pressure Instead

• “Trust ABI when low but not when high.”

• Toe pressures have proven to be an excellent option for the

diagnosis of PAD in patients at risk for falsely elevated

ABI >1.4 values.

• Toe arteries are smaller and more easy to occlude.

• Accurate toe pressures require sensitive techniques such as

laser Doppler.

International Consensus on the Diabetic Foot and Practical Guidelines on the Management and Prevention of

the Diabetic Foot, International Working Group on the Diabetic Foot, 2012

Right foot:

Ankle pressure = 146 mmHg

ABI = 1.22

Toe pressure = 42 mmHg

Baseline tcpO2 = 43 mmHg

Combine Several Vascular Tests

Example: Male with painful left foot and amputated toes.

Results from several

tests will give a better

overview of the limb

circulation.

Here : Patient with

clear PAD but no CLI.

Left foot:

Ankle pressure = incompressible arteries

Toe pressure = no toes

Baseline tcpO2 = 42 mmHg

Normal Ankle Pressure

and ABI. Is this really

reliable or the beginning

of media sclerosis and

falsely elevated ABIs?

Adjusting Pressure

Markers?

Standard Recording

Pressure markers are

automatically set at the

return of flow

Toe pressure

Blo

od P

erf

usio

n

Time (s)

Sometimes Adjustments are Required

• Laser Doppler probes are sensitive to motion

• Artifacts may trigger a faulty pressure registration

Biphasic Patterns upon Re-flow

C. HØyer. et al., Reliability of laser Doppler flowmetry curve reading for measurements of toe and ankle pressures:

intra- inter-observation variation, European Journal of Vascular Endovascular Surgery, 2014, in press

Clear distinction between phases Overlap between phases

Time (s)

Pe

rfu

sio

n (

PU

)

0

100

200

Time (s)

Perf

usio

n (

PU

)

0

100

200

Two phase (“bumps”) in the curves are:

• Arterial inflow (A) – veins are closed

• Unrestricted flow (V) – all vessels are open

• Place pressure marker at A

Exclude Measurements

There is always a

possibility to exclude a

measurement if

necessary.

Best Practice – 3 Repetitions

• Always perform three (3) consecutive measurements

• Maximum variation between two pressures < 10 mmHg

• If the variation is more than 10 mmHg, perform another

measurement

1 145

2 146

3 128

4 143

Four consecutive ankle pressures.

The 3rd pressure differs more than 10 mmHg

compared to the other pressures and is discarded.

Summary

Be consistent. Develop your own internal rules.

Perform multiple measurements.

Think physiologically!

Thank You!

PeriFlux 6000 | peripheral pressure made intelligent

www.perimed-instruments.com