A Dry Black Heel Eschar in a Patient With Diabetes and Peripheral Arterial Disease
Mrs. S, 74, is admitted with a pressure injury over the right heel measuring 3.5 by 2.8 cm, covered by a dry, firmly adherent black eschar. Right ankle-brachial index is 0.62; left is 0.95. She has type 2 diabetes with an A1c of 9.4% on insulin, and stage 3 chronic kidney disease. Dorsalis pedis and posterior tibial pulses are barely palpable on the right; the foot is cool with dependent rubor and 2+ pitting edema. She is in bed most of the day, has a Braden score of 12, and cannot feel the heel on 10 g monofilament testing. There is no drainage, fluctuance, or spreading erythema.
1. The wound care nurse asks whether you will debride the eschar. What is your answer and rationale?
Read the worked answer
No - not by sharp debridement, and not by me without a vascular assessment.
Reasoning:
- A dry, stable, adherent heel eschar with no drainage, fluctuance, or erythema in a patient with arterial insufficiency is best left intact. It acts as a natural biologic cover. Removing it converts a closed wound into an open wound with a blood supply that may be inadequate to heal it - the classic path to a non-healing arterial ulcer or amputation.
- The ABI of 0.62 indicates moderate arterial disease and is a caution flag, not a clearance. In a patient with long-standing diabetes, the ABI can also be falsely elevated by medial arterial calcification, so true perfusion may be worse. Toe pressures or a toe-brachial index and a vascular surgical consult are the appropriate next steps.
- What does change the answer: signs of infection (spreading erythema, purulence, undrained fluctuance, systemic illness), wet drainage, or exposed underlying structures. Those warrant urgent escalation regardless of the ABI.
Your plan: protect the eschar, keep it dry, offload, and refer for vascular assessment and a wound care plan. Document the decision and who was notified.
2. Write the offloading and positioning plan you would implement today, and explain each element.
Read the worked answer
Offloading (the single most important intervention):
- Heel suspension boot or a pressure-redistributing device worn in bed and in the chair, designed to float the heel. Nothing should contact the eschar.
- Pillow under the calf, not under the heel, so the heel hangs free. A pillow placed under the Achilles area can still create pressure and can contribute to equinus contracture.
- No donut cushions - they concentrate pressure at the rim.
- Reposition every 2 hours, including overnight. The Braden score of 12 means she needs this schedule, not a reminder to "turn when she can."
- Pressure-redistributing mattress and a chair with the heel free of the leg rest; limit sitting time.
Positioning nuance: with dependent rubor and arterial disease, prolonged leg elevation above heart level can worsen perfusion even though it helps edema. Discuss the competing priorities (edema vs arterial supply) with the team rather than defaulting to elevation.
Also protect the other foot: check footwear and the left heel, and inspect the feet daily, since she cannot feel them.
3. Her daughter asks about massaging the heel and using wet-to-dry dressings "to get the black off." How do you respond?
Read the worked answer
Respond directly, with the reason attached to each answer.
- Do not massage the heel or any reddened area. Massage on fragile, ischemic tissue adds shear and pressure over bone and can cause further breakdown. It also feels productive to families, which is exactly why it needs a clear explanation.
- Wet-to-dry dressings are not appropriate here. They are non-selective - they pull off viable tissue along with the eschar - they are painful, and they would dry out and mechanically disturb a stable eschar. The current plan is to keep it dry and protected, not to remove it.
- Explain why the black tissue stays. With her circulation, that dry cap is protective. Removing it before the blood supply is evaluated could create a wound that will not heal.
Give the family a job that matters:
- Check the heel and both feet daily and report increased drainage, odor, spreading redness, warmth, fever, new pain, or a black area that is expanding.
- No barefoot walking, no heating pads or hot water bottles, and shoes checked with a hand inside before putting them on - she cannot feel injury.
Close the loop by telling them who to call and documenting that the education was given and understood.