Stopping pressure ulcers—before they start

Nursing Homes, May, 2004

Wound care expert Courtney H. Lyder's mention in our January issue of ultrasound technology for use in assessing pressure ulcers ("Battling Pressure Ulcers: Consistency Means Success," p. 72) prompted a flood of e-mails from readers seeking more information. In response to those inquiries, Nursing Homes/Long Term Care Management Editor Linda Zinn asked Steve Mogensen and John Hertig of Advanced Clinical Services--the provider to the long-term care market of a new wound care management service using Longport, Inc.'s portable high-frequency ultrasound scanner--to explain how this technology works for pressure ulcer prevention and assessment, what equipment is required and who can use it, how much it costs, and what benefits can be expected. Their comments follow.

Zinn: How does ultrasound technology work in detecting potential pressure ulcers and assessing existing ones?

Mogensen: High-frequency ultrasound enables clinicians to view high-resolution images of the underlying few centimeters of the skin's soft tissue and to detect changes beneath the skin's surface that indicate that a pressure ulcer is developing. We use a three-phase classification system that shows developing pressure ulcers before they can be detected by sight or touch. At Phase 1, pockets of subcutaneous edema, or fluid, can be seen, starting near the bone (figure, A). Fluid is nonreflective, so it shows up as darker tissue on the scan. At Phase 2, strips of dermal damage, along with increased subcutaneous damage, can be detected (figure, B). At Phase 3, subepidermal inflammation is discernible, along with strips of dermal damage and major subcutaneous damage (figure, C). The next step after Phase 3 is total breakdown, at which time the wound becomes visible on the surface of the skin. The transition from Phase 3 to total breakdown can take just hours or it can take days, but without this technology, pressure ulcers developing below the skin's surface only can be detected by sight or touch approximately 25% of the time.

For assessing existing pressure ulcers, the scans show the extent and severity of subdermal edema and tissue damage.

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Zinn: Some adverse effects have been reported with ultrasound when it's used for treating wounds. How safe is it when it's used diagnostically?

Mogensen: The frequency of the ultrasound is higher with diagnostic scanners. Ultrasound equipment used therapeutically is in the low-frequency range--1 to 4 MHz--and at these frequencies, you have to be careful to avoid burns. But scanners used for diagnostic purposes--for example those used for bladder scans, fetal monitoring, and heart exams--are generally in the 4-to 12-MHz range and are not associated with burning or any other adverse effects. The technology we use is noninvasive, operating at 20 MHz. Not only does this high frequency make the scanner safe, but it also provides sharp, high-resolution scans. Because these ultrasound waves can't penetrate very far--roughly the thickness of five to ten dimes--before they have to come back to the receiver, you could rest it on someone's skin all day with no adverse effects.

Zinn: What else do these high-frequency ultrasound scans reveal?

Mogensen: A trained radiologist can tell from the images whether a developing wound is actually a pressure ulcer or if it's a friction ulcer. The radiologist can also pinpoint the source of the developing wound, even when it's being caused by incontinence.

Zinn: How do the radiologists make these distinctions?

Hertig: These are experienced clinicians who are trained to evaluate the tissue breakdown that's visible on the scans. Sometimes they can determine the type of wound because of its location--e.g., near the surface just under the epidermis, as with a friction ulcer, versus deep above a bony prominence, as with a pressure ulcer. In other cases they can tell by the composition of injured tissue. This enables them to recommend the appropriate intervention, i.e., correcting an incontinence problem versus providing pressure relief versus removing a source of friction.

Mogensen: A friction ulcer looks much like a pressure ulcer, but it develops just below the surface of the skin, where friction against an external surface is occurring. Pressure relief doesn't help a friction ulcer.

With a pressure ulcer, you're looking at fluid that starts at the bone and works toward the surface. The location and amount of fluid tells the radiologist not only what's causing the problem, but also how serious that problem is.

Hertig: In addition to facilities' caregivers using a "shotgun" approach that involves turning every at-risk resident every two hours, they now can target the intervention much more precisely by following our radiologist's recommendations, which are based on the interpretation of the scans.

Mogensen: Those recommendations consist of a set of preventive protocols [see sidebar, "Soft-Tissue Management Interventions With Use of High-Frequency Ultrasound"]. We worked with nursing homes, reviewing their existing protocols, to develop these.