A short guide to interpreting tcpO2 data.

1. Interpreting Curves and Results
PeriFlux 6000 | tcpO2 made intelligent

2. 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.
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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.

3. • Calibration
• tcpO2 Site Selection
• Electrode Maintenance
• Interpreting Curves and Results

4. Transcutaneous oxygen (tcpO2 / TCOM)
Reference values
50-70 mmHg Normal
< 40 mmHg Impaired Wound Healing
< 30 mmHg Critical Limb Ischemia
Measures the local oxygen tension in the skin
deriving from the local capillary (nutritive) blood
perfusion.
• Predicts wound healing potential
• Helps define degree of small vessel disease
• Accurately determines amputation level
• Monitors efficacy of patients ongoing therapy
• Establishes candidacy for HBO treatment

5. Influencing Factors
• Impaired macrocirculation - Peripheral Arterial Disease
• Capillary impairment
or…
• Cardiopulmonary disease
• Edema
• High consumption of O2 (e.g. infection or inflammation)
• Hair
• Topical skin products, lotions, dirt, grease…
• Bony prominences, sharply curved anatomy, calloused
skin…

6. Procedure Details
• Typical procedure:
– 15 minute baseline
– 5 minute leg elevation
– 5 minute post-elevation
– 10 minute oxygen challenge
• Above procedure can also be done without leg
elevation (if large vessel disease has been ruled out).
Provocations

7. Typical Data

8. Why Provocations?
• Leg Elevation Test
Lift legs 30° with wedge.
May be used to confirm macrovascular disease.
• Oxygen Challenge
tcpO2 measurement during 100 % oxygen inhalation.
Discriminates between vascular disease and barriers to
diffusion such as edema and/or inflammation. Identifies
candidates for HBO therapy.

9. Leg Elevation Test
Lift legs 30°
– Expect a drop of < 10 mmHg and/or < 20% (of
baseline value).
– Values should revert to baseline after wedge
(30°) is removed.
– Other methods to confirm macrovascular
disease include toe and ankle pressure.

10. O2 Challenge
tcpO2 measurement during 100% oxygen inhalation
– Expect > 100 mmHg and/or > 100% increase
from baseline.
– A tight fitting mask, e.g. an NRB mask at 15
l/min, is essential for a successful O2
challenge.
IMPORTANT
Patients with chronic obstructive
pulmonary disease should NOT be
subjected to an O2 challenge.

11. Example 1 - O2 Challenge
Baseline
tcpO2 = 10 mmHg
O2 challenge
tcpO2 = 105 mmHg
Low tcpO2 values due to barrier to O2 diffusion.
Confirmed by good response to O2.
Wound healing potential exists. Candidate for HBO.

12. RIGHT
LEFT
tcpO2 baseline = 64 mmHg
tcpO2 baseline = 43 mmHg
Example 2 – O2 Challenge
Patient with wound on right foot.
Low toe pressures on both sides (R = 16 mmHg, L = 18 mmHg)
Is the right side tcpO2 value reliable or is it falsely high?
tcpO2 curve shape slowly declining. No initial “dip”(compared with left).
Toe pressure results indicate severe macrocirculatory problems (< 30 mmHg).
An O2 challenge would have been useful!
No response to O2 would have confirmed severe microcirculatory disturbance.

13. Example 3 – O2 Challenge
Similar curves for which an O2 challenge would have
been beneficial for the interpretation!
No initial dip. Slowly
declining tcpO2.
Leakage at end of
measurement?
Falsely high baseline
value?
True low value due to
PAD or falsely low due
to barrier to O2
diffusion?

14. Leakage
Unreliable data...
Spikes in the curve are
usually due to leakage.
Leakage can also easily be
verified by spraying oxygen
around the fixed electrode!

15. Faulty setup?
Expect an initial ”dip” in the tcpO2 curve directly after
the electrodes have been positioned in place.
Curves with no initial dip.
1. Re-position fixation ring to make sure that the site preparation is ok.
2. If there is still no dip and the baseline is slowly declining, perform an
O2 challenge to evaluate severe microcirculatory disturbance.
Initial dip in tcpO2

16. Oscillations
Regular variations...
May be due to
physiological reasons
such as a respiratory
problem causing
varying oxygen
delivery or, a cardiac
output problem
causing quick
oscillations in the
supplying arterial flow.
CHEST
CALF
FOOT

17. Other Tips
• Contralateral reference and/or pulse oximeter…
…rules out arterial hypoxemia due to e.g. pulmonary
disease.
• A mean of several tcpO2 values…
…is a better predictor of wound healing potential than
single site values.
• To establish candidacy for HBOT (Hyperbaric Oxygen
Therapy)…
…expect in-chamber value: tcpO2 > 200 mmHg

18. Perform Additional Vascular Tests
• Add other pieces of information
– Toe pressure and ABI
– Pulse Volume Recording (PVR)
– Segmental pressures
– Tissue response to local heating (Heat-
controlled laser Doppler)
– Skin Perfusion Pressure (SPP)

19. Toe Pressure - TBI
• Toe pressures/TBI are more reliable than ankle
pressure in patients with calcified vessels (ABI > 1.40)
– 30 - 40 % of patients with diabetes show falsely high ABIs.
– ABI > 0.6 has low predictive value for healing in patients with
calcified vessels.
• Requires sensitive technique
– Laser Doppler is sensitive at low pressures.
– Solution for cold ischemic feet – built-in local heating.

20. Left foot:
Toe Pressure = 70 mmHg
Baseline tcpO2 = 10 mmHg
tcpO2 during O2 challenge = 105 mmHg
Combining Toe Pressure and tcpO2
Example: Female with painful, discolored left foot.
Falsely low tcpO2
value on left foot
due to barrier to
O2 diffusion
confirmed both by
O2 challenge and
toe pressure.
Right foot:
Toe Pressure = 68 mmHg
Baseline tcpO2 = 57 mmHg
tcpO2 during O2 challenge = 167 mmHg

21. Right foot:
Ankle Pressure = 146 mmHg
ABI = 1.22
Toe Pressure = 42 mmHg
Baseline tcpO2 = 43 mmHg
Combining Toe Pressure and tcpO2
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?

22. Tissue response to local heating
Baseline Heat induced vasodilatation
Spontaneous healing likely when
Max perfusion during heat > 20 PU (> 100 PU if inflammation)
and/or > 150 % increase from baseline during heat
• Measures the total local blood perfusion in the tissue -
capillaries, arterioles, venules and shunts.
• Evaluates wound healing potential.

23. Combining laser Doppler and tcpO2
tcpO2
> 30 mmHg
Responds to O2
Tissue response to heat
Responds well to heat
Example – Patient with wound healing potential (healer)

24. Combining laser Doppler and tcpO2
Example – Patient non-healing wound
tcpO2
< 30 mmHg
Minimal response to O2
Tissue response to heat
No response to heat

25. Combining laser Doppler and tcpO2
Example – Patient with inflammation
tcpO2
< 30 mmHg
Responds to O2
Tissue response to heat
High initial baseline
Responds to heat

26. Guidelines and Consensus Documents
Document Society/Association Published
Practical guidelines on the management and
prevention of the diabetic foot
IWGDF – International Working
Group on the Diabetic Foot
2007, 2012
Guidelines for Critical Limb Ischemia and
Diabetic Foot
ESVS (European Society for
Vascular Surgery) CLI Guideline
Committee
2011
ACC/AHA 2005 Guidelines for the Management
of Patients With Peripheral Arterial Disease:
Executive Summary, Update 2011
ACC/AHA (American Collage of
Cardiology/American Heart
Association)
2005, 2011
Transcutaneous Oximetry in Clinical Practice:
Consensus statements from an expert panel
based on evidence
Fife CE, Smart DE, Sheffield PJ,
Hopf HW, Hawkins G, Clarke D
2009
Comprehensive Foot Examination and Risk
Assessment
ADA (American Diabetes
Association )
2008
Inter-Society consensus for the Management of
Peripheral Arterial Disease
TASC II 2007

27. Thank You!
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www.perimed-instruments.com