UC UC SF SF Disclosures Vascular Assessment of the Diabetic Foot - - PowerPoint PPT Presentation

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UC UC SF SF Disclosures Vascular Assessment of the Diabetic Foot - - PowerPoint PPT Presentation

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UC UC SF SF Disclosures Vascular Assessment of the Diabetic Foot What are the best predictors of wound healing? None Shant Vartanian MD Assistant Professor of Vascular Surgery UCSF Vascular Symposium April 20, 2013 VASCULAR SURGERY

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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Vascular Assessment of the Diabetic Foot What are the best predictors of wound healing?

Shant Vartanian MD Assistant Professor of Vascular Surgery UCSF Vascular Symposium April 20, 2013

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Disclosures None

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Non-Invasive Vascular Studies

  • Adds objectivity to clinical history and physical exam
  • Location and severity of PAD
  • Potential for primary healing of a wound or surgical

incision

  • Planning of surgical intervention or amputation level

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Non-Invasive Vascular Studies

  • Physiologic or Hemodynamic
  • Ankle brachial index
  • Toe brachial index
  • Pulse volume recordings
  • Exercise treadmill testing
  • Anatomic imaging
  • Duplex ultrasound
  • Tissue perfusion
  • TcPO2
  • SPP (plethysmography, laser doppler)
  • Spectral imaging (Indocyanine green angiography)
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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Andersen CA J Vasc Surg 2010; 52:Suppl S

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Ankle Brachial Index

http://www.nhlbi.nih.gov/health/dci/Diseases/pad/

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Ankle Brachial Index

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Ankle Brachial Index

  • Ankle pressure > 60 mm Hg is required to heal ulceration

in non-diabetics

  • Ankle pressure of > 80 mm Hg for reliable healing in

diabetics

  • More accurate if normalizing to brachial pressure
  • High rates of healing if ABI > 0.8
  • Ballard et al
  • 66 limbs with diabetic wounds
  • 89% healed if ABI > 0.6
  • ABI < 0.6 associated with need for revascularization
  • Poor wound healing if ABI < 0.4
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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Ankle Brachial Index

J Vasc Surg 1995 vol. 22 (4) pp. 485-90

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Ankle Brachial Index

  • Common errors
  • Oversized cuffs
  • Not measured in supine position
  • Limitations
  • Wide distribution of measurements for any given outcome
  • Falsely elevated in calcified, non-compressible vessels

– Diabetes – Renal failure

  • Ankle pressures may not accurately represent pedal/digit

circulation

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Toe Brachial Index

http://www.nhlbi.nih.gov/health/dci/Diseases/pad/

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Toe Brachial Index

  • Digit pressures
  • Photoplethysmography

– Light emitting diode on distal toe pad – Photocell recieves back-scattered infrared light – Detects increase in flow as cuff is deflated

  • Continuous wave Doppler

– Detects increase in flow as cuff is deflated

  • Absolute toe pressures < 30 mm Hg
  • Predicts failure to heal
  • Increased risk of amputation
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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Toe Brachial Index

  • Meta analysis to calculate sensitivity and specificity of

ABI and TBI to predict ulcer healing

  • Included 220 limbs from 3 studies
  • 50% were diabetics
  • Best performance of each test by maximizing ROC
  • Ankle pressure > 80 mm Hg
  • Toe pressure > 30 mm Hg
  • Limitations
  • Body/room temperature can effect results
  • Can not discern between fixed obstruction and vasospasm

VASA 1998 Nov;27(4):224-8.

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Transcutaneous Oxygen Tension

  • Measures metabolic state of the skin
  • Electrode with heating element placed on skin
  • Measures oxygen diffusion from skin
  • O2 reduced at cathode to produce current proportional to

the partial pressure of oxygen (PO2)

  • Insensitive to mild or moderate PAD
  • When low, TcPO2 is not linearly related to flow
  • Advantages
  • Ideal for assessing severe ischemia

– Determining amputation level

  • Can be applied to any area

– Patients with previous toe or midfoot amputations

  • Not affected by arterial calcification

VASA 1998 Nov;27(4):224-8.

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Transcutaneous Oxygen Tension

  • Systematic review and meta-analysis
  • 31 studies with 1824 patients and 1960 amputations
  • TcPO2 < 40 results in 24% increase in risk of healing

complications

  • Increases further as TcPO2 decreases

Eur J Vasc Endovasc Surg 2012 vol. 43 (3) pp. 329-36

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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Transcutaneous Oxygen Tension

Eur J Vasc Endovasc Surg 2012 vol. 43 (3) pp. 329-36

“Insufficient evidence to judge whether this tool adds important information beyond clinical data or to suggest an optimal threshold value”

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Transcutaneous Oxygen Tension

  • Limitations
  • Labor intensive
  • Time consuming
  • Many factors effect outcomes

– Skin temperature – Room temperature – Sympathetic tone – Active infection – Venous disease – Etc.

VASA 1998 Nov;27(4):224-8.

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Skin Perfusion Pressure

  • Technique to assess tissue perfusion
  • Controlled occlusion with cuff
  • The pressure at deflation at which circulation in sub-

dermal capillaries is restored

  • Circulation measured with a laser doppler
  • Commercial systems
  • SensiLase
  • Perimed
  • Advantages
  • Point of care testing
  • Relatively quick studies
  • Works on patients with

toe amputations

VASA 1998 Nov;27(4):224-8.

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Skin Perfusion Pressure

  • 62 limbs in 53 patients with diabetic wounds
  • Evaluated healing rate at one month
  • Stratified results by SPP > 40

Ann Vasc Dis 2009 vol 2 (1) pp 21-6

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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Skin Perfusion Pressure

  • Limitations
  • Sensitive to room temperature
  • Body temperature
  • Patient position
  • Active infection

VASA 1998 Nov;27(4):224-8.

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Comparative Effectiveness

  • Comparison of ABI, TBI, TcPO2 and SPP in 403 limbs
  • Diabetes 50%
  • ESRD 21%
  • SPP measured successfully in 100%
  • ABI 87% (Elevated ABI)
  • TBI 91% (Toe amputation, wound)
  • TcPO2 94% (Pain)
  • Healing and amputation rates
  • Strong correlation between SPP and TBI
  • For SPP threshold of 40 mm Hg
  • Sensitivity 72%
  • Specificity 88%

JVS 2008 vol. 47(2) pp. 318-23

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

JVS 2008 vol. 47(2) pp. 318-23

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

JVS 2008 vol. 47(2) pp. 318-23

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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

JVS 2008 vol. 47(2) pp. 318-23

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Indocyanine Green Angiography

  • Inert non-radioactive contrast agent administered as IV injection
  • Laser source to excite fluorescent molecule indocyanine green
  • Camera captures fluorescence with intensity proportion to the

perfusion to a given area

  • Regional perfusion information
  • Unknown ability to predict wound healing

JVS in press

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Indocyanine Green Angiography

JVS in press

UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Andersen CA J Vasc Surg 2010; 52:Suppl S

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UC SF

VASCULAR SURGERY • UC SAN FRANCISCO

Summary

  • Single threshold value for non-invasive studies does not

always perfectly predict which wounds will heal

  • Importance of history, exam and clinical course
  • In diabetics and in renal failure, toe pressures correlate

well with ability to heal

  • SPP appears to work equally as well

JVS in press