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Wound Formation, Treatment, and Healing

The occurrence of pressure ulcers among the elderly and in hospitalized patients has an extensive impact on patients and health care providers in terms of decreased quality of life, loss of productivity, and high cost of treatment. Various studies indicate that 50-60% of all pressure ulcers in acute hospital populations develop after admission and thus are deemed preventable (i.e., more frequent risk assessment, treatment plans, specialty devices, etc.). Although extensive literature exists concerning pressure ulcers, there remains no clear consensus regarding the etiology of such wounds. Rather, several factors are known to contribute to the formation and persistence of pressure-related wounds (i.e., elevated pressure over extended time, shear, elevated pressure augmented by elevated temperature, age, poor nutrition, incontinence, fractures, paralysis or lack of sensation, arterial insufficiency, venous stasis, diabetes). Specifically, there are few detailed reports about the thresholds of wound formation with respect to pressure, temperature, and duration of application, and lack of clear consensus about the proper form of treatment. Clinicians use a variety of visual methods to evaluate the status of skin tissue, however these methods lack precision, and quantification of slow or subtle changes may be difficult. Accurate determination of the extent and depth of subsurface injuries would allow for appropriate and timely therapeutic intervention.

Related studies in our lab include the following:

Figure 1. Cluster of 4 discs was designed to apply pressure to preselected wound sites. Temperature
modulation was facilitated with a micro-processor-controlled unit; cooling was provided by a water
bath and heating by electrical resistance wire. Temperatures were maintained within ±0.5°C.

Figure 2. Disc application and subsequent assessment sites

Figure 3. Illustrative representation of tissue damage at combinations of pressure,
temperature, and duration that resulted in tissue alterations


  1. Kokate JY, Leland KJ, Held AM, Hansen GL, Kveen GL, Johnson BA, Wilke MS, Sparrow EM, Iaizzo PA: Temperature-modulated pressure ulcers: a porcine model. Archives of Physical Medicine and Rehabilitation 76: 666-673, 1995.
  2. Iaizzo PA, Kveen GL, Kokate JY, Leland KJ, Hansen GL, Sparrow EM: Prevention of pressure ulcers by focal cooling: histological assessment in a porcine model. Wounds: A Compendium of Clinical Research and Practice 7: 161-169, 1995.
  3. Hansen GL, Sparrow EM, Kammamuri R, Iaizzo PA: Assessing wound severity using color and infrared imaging of reactive hyperemia. Wound Repair and Regeneration 4: 386-392, 1996.
  4. Hansen GL, Sparrow EM, Kokate JY, Leland KJ, Iaizzo PA: Wound status evaluation using color image processing. IEEE Transactions on Medical Imaging 16: 78-86, 1997.
  5. Kokate JY, Leland KJ, Sparrow EM, Iaizzo PA: Critical thresholds for pressure ulcer formation in a porcine model. Wounds: A Compendium of Clinical Research and Practice 9: 111-121, 1997.
  6. Hansen GL, Sparrow EM, Kalieta AL, Iaizzo PA: Using infrared imaging to assess the severity of pressure ulcers. Wounds: A Compendium of Clinical Research and Practice 10: 43-53, 1998.

Patents Related to this Research:

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