Strategies for aggressive management and prevention.
Isa McClure, PT, MAPT, and Conchita Rader, RN, MA, CFCN, CWCN
Pressure ulcers (PrUs) are one of the most common and serious complications affecting people with spinal cord injury (SCI). It has been estimated that anywhere from 50% to 80% of persons with SCI can develop a pressure ulcer. Pressure ulcers can be a major cause of morbidity and mortality in SCI and are one of the most common secondary complications all years after injury. In a study of 1,649 persons with new spinal cord injury, of all medical complications, pressure ulcers occurred with high frequency and developed in 23.7% of patients during the acute rehabilitation phase.1 The incidence of PrUs increases with the duration of the SCI. The annual incidence has been reported to be 31% to 52% with up to 79% of the SCI population troubled with recurrent ulcers. Approximately 8% of those who develop pressure ulcers will die from related complications.
Contributing Factors in Pressure Ulcer Development
The effect of excessive pressure on soft tissue can be attributed to a combination of factors: (1) intensity of the pressure, (2) duration of the pressure, and (3) tissue tolerance. The duration of pressure, along with the intensity of pressure, can create tissue ischemia. The ability of the skin to respond to ischemic stress has been studied to explain the role of ischemia in pressure ulcer development. It is hypothesized that prolonged mechanical loading of the tissue obstructs the arterial blood vessels, thus causing local ischemia, which, when applied over a long duration, can cause cell necrosis.2 Cellular necrosis caused by the accumulation of metabolic waste products has been shown to be a major contributing factor to pressure ulcers. Capillary closing pressure is generally used to indicate the intensity of pressure on any given bony prominence. It is common to use the capillary pressure of 12 to 32 mm Hg as the standard for collapsing a capillary.3 In addition, the interface pressure, the pressure between the patient’s skin and the resting surface, is used to quantify any external pressure applied to the skin. Tissue tolerance is the ability of the skin and its supporting structures, such as the blood vessels, interstitial fluid, and collagen, to endure the pressure without adverse effects. Tissue tolerance is influenced by shear, friction, moisture, nutritional debilitation, advanced age, low blood pressure, emotional stress, and smoking.
Following injury, individuals with SCI experience a loss of muscle bulk and muscle atrophy in the paralyzed muscles below the level of injury. Wu and Bogie4 found, in comparative gluteal region CT images of 10 able-bodied and 10 SCI persons, that the SCI group had altered gluteal muscle characteristics. They found that both low density muscle and adipose tissues occurred in higher proportions in the SCI population. Gluteal muscle atrophy was greater at the level of the ischial tuberosities, thereby decreasing the cushioning of the soft tissues surrounding the bony prominences. Pressure ulcers most commonly occur at the ischial tuberosities due to the pressures associated with sitting, followed by the sacrum, in those with chronic SCI.
The major focus of the rehabilitation team is to educate both patient and caregiver to prevent the development of pressure ulcers. This includes education regarding etiology, risk factors, and proper positioning; prescribing appropriate equipment including pressure-relieving cushions; and performance of timely and effective weight shifting, as well as nutrition. Wheelchair specialty cushions are recommended for all full-time wheelchair users with SCI when sitting. The primary purpose of protective support surfaces is to reduce pressure over the bony prominences and assist in the prevention of pressure ulcers. The key is to trial and assess via interface pressure mapping under the supervision of a trained clinician to assist in determining which support surface would be effective in redistributing pressure over the bony prominences.
Dynamic sitting stability plays an important role in weight shifts and seat-interface pressure distribution. For SCI patients, impaired dynamic sitting stability is associated with the development of pressure ulcers.5 Repositioning and weight shifting are important to help with the management of PrUs. Done while sitting, they can assist with reoxygenation of the soft tissue. Weight shifts can be performed by the patient with or without assistance. They can be performed in an anterior, posterior, or lateral position, as well as via a full press up. The press up is the most difficult to perform. If the patient is unable to perform their own weight shift, the patient’s caregiver tilts the chair posteriorly so that the patient’s weight is no longer on their ischial tuberosities. All of these weight shift maneuvers will relieve the pressure from the sacral, gluteal, and ischial tuberosities and redistribute it to other areas to allow reperfusion of the ischial areas. Muscle atrophy in these areas is common in SCI patients; little soft tissue remains to help redistribute or relieve pressure over the bony prominences.
Interface pressure mapping (IPM) is a computerized pressure-sensitive mat that measures pressure between the skin and the sitting surface. It provides both visual and statistical data that represent the pressure distribution between the gluteal muscles and the wheelchair seat cushion. These data can be utilized to determine how successfully a seating system optimizes load distribution. Unfortunately, there is no established and clear cut-off point for interface pressure for the development of PrUs. The question that remains is how often and how long should an individual with SCI perform a weight shift? It has been reported that it took approximately 2 minutes of pressure relief to raise tissue oxygen to unloaded levels for most subjects who were tested.6 Power wheelchairs can provide weight shifts if the individual is unable to independently perform an effective weight shift, especially if they do not have a caregiver with them at all times. However, proper positioning and alignment in the wheelchair is essential to assist in helping prevent PrUs on the sacral and ischial tuberosities. Jan et al7 found that skin perfusion over the ischial tuberosities, during recovery at a 3-minute duration of tilt-in-space and recline, was significantly higher than the 1-minute duration.
Recent literature has suggested that the right cushion can actually delay the onset of sDTI (suspected deep tissue injury). No one cushion is suitable for all individuals with SCI, and there are a plethora of cushions available on the market. No one single cushion has been identified as being more or less appropriate than others for people with spinal cord injury. IPM can be utilized in identifying those cushions that redistribute load away from the soft tissue compressed by the bony prominences. Coggrave and Rose8 stated in 2003 that it took 1 minute 51 seconds to raise tissue oxygen level to the original unloaded level. Trialing different cushions, in conjunction with IPM, prior to cushion selection can make relative comparisons between surfaces as well as rule out cushions that do not optimize load distribution.
There are many different types of wheelchair cushions on the market today. However, there is no one type that is appropriate for all clients. A thorough seating evaluation by an Assistive Technology Practitioner is necessary to determine each person’s needs and to create successful seating and mobility for each specific client. Since the purpose of the cushion is to provide safety and stability, as well as to assist in reducing soft tissue trauma, the question remains…which cushion is best? Cushions are composed of various materials including viscoelastic foam, solid gels, fluid gels, and air. Each material has special properties as well as specific differences in temperature and shear management.
Foam tends to be the simplest material because it is easily manipulated and can be utilized to create contours for the bony prominences of the pelvis. However, foam is a poor conductor of heat and can contribute to increases in skin temperature. There is very little maintenance required with foam cushions, and the materials tend to be lightweight and inexpensive. Newer foams may have the ability to not build up as much heat as the more traditional foams, but they are still temperature sensitive and should not be left out in the cold. Foam and viscoelastic foam cushions also tend to contribute to increased shear on the bony prominences during transfers.
There are two different types of gel cushions. Solid gel cushions tend to be much heavier than foam cushions and also provide a reduction in shear forces on the skin. These particular cushions also may be used in conjunction with a foam base. These cushions are not as temperature sensitive and may actually assist in cooling the skin.
Fluid gels also promote reduction in shear. However, due to the constant movement of the materials, there is a risk of “bottoming out,” which may affect patient balance and positioning. Maintenance is required for these cushions to ensure that the bony prominences are supported at all times.
Solid gel, viscous fluid, and air cushions may decrease shear forces experienced during scooting and transfer training due to improved ability for both the patient to move and to assist the patient to move.
It is important to remember the role played by the cushion cover. The material of the cover can assist in the transfer of heat away from the buttocks. All patients and clients should be educated that the appropriate use of the cover can help assist with both proper fit and air exchange. Ultimately, it is up to the client to make the final choice of cushion. However, education regarding positioning, maintenance, and function, as well as comfort and cost, must be exchanged.
In addition to turning, repositioning, and the use of effective support surfaces, other strategies that play a critical role in pressure ulcer prevention and healing include nutritional supplementation, moisture management, and regular skin assessment. These prevention strategies are driven by the major factors that increase the patient’s risk for developing pressure ulcers: friction and shear, pressure, fecal and urinary incontinence, diminished sensory perception, and malnutrition.
• Moisture Management. The use of breathable products, briefs, and underpads helps prevent exposure of the patient’s skin to moisture from incontinence by wicking the fluids into the pads.
• Friction and Shear. They can be prevented by lifting, not dragging, the patient, and if the patient is a bariatric patient, a turning and positioning system would be effective in assisting them to assume a 30-degree lateral position.
• Nutritional Supplementation. There is no single definitive parameter for adult malnutrition. The Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition listed six characteristics for identification and diagnosis of adult malnutrition in clinical settings. These are: (1) insufficient energy intake, (2) weight loss, (3) loss of muscle mass, (4) loss of subcutaneous fat, (5) localized or generalized fluid accumulation that may sometimes mask weight loss, and (6) diminished functional status as measured by hand grip.9 Adult malnutrition can be addressed by proper nutritional supplementation, usually protein supplements.
• Vigilant Skin Monitoring. Regular skin assessments are critical to prevent skin breakdown and recognize early signs of breakdown. In addition, risk assessment, using a validated risk assessment tool, is advised. The Braden Scale is a more universally used risk assessment tool.
• Proper patient positioning and pressure relief should begin immediately after SCI, as soon as the patient and spine are stabilized. Since PrUs occur over bony prominences, depending on the patient’s position, different bony prominences are at risk. When sitting, the ischial tuberosities bear the weight of the upper body and are therefore at greatest risk. In side lying, the greater trochanters become at risk; and in the supine position, the sacrum, heels, and occiput are at risk for PrU development. When in bed, it is recommended that patients be repositioned and turned laterally at 30 degrees every 2 hours, with the head of the bed raised no higher than 30 degrees unless the patient experienced respiratory and circulatory risk.
• Pressure Redistribution Support Surface. There are many different mattress replacements, overlays, and integrated bed systems that are available and may assist in the prevention of PrU development. There are active support surfaces, ie, they redistribute pressure whether or not the patient is moving, and there is the reactive upport surface that redistributes pressure only when triggered by patient movement. For individuals with SCI, an active support surface is effective due to its dynamic pressure relief on a continuous basis. Jan et al,10 in a study comparing the effects of alternating and constant pressures on weight-bearing tissue perfusion, found that alternating pressure enhances the skin perfusion of weight-bearing tissues. Those patients who have the ability to turn and reposition, although limited, can benefit from the use of a reactive support surface—a low-air loss mattress, for example. It is critically important to arrive at this decision with the interdisciplinary team to provide the best pressure relief for patients with limited mobility.
Electrical stimulation therapy (ES) in wounds involves the use of an externally applied current to create an electrical flow through the soft tissues with electrodes placed on the skin near the wound and the saline-moistened gauze placed over the wound. The saline provides a conductive medium that allows electric current to pass directly through the wound. Electrical stimulation can help speed wound healing by increasing capillary density and perfusion, improving wound oxygenation, and encouraging granulation and fibroblast activity.
The two main approaches to delivering ES include the use of technology that provides direct current as well as technology that provides a pulsed current. Electrical stimulation using direct current involves a one-way flow of electrons between the positively and negatively charged electrodes placed in or adjacent to the wound. The applied current is in the microamperage range and maintained for 1 second or longer with no pulses in the flow. Electrical stimulation using a pulsed current comprises a cyclic flow and no flow of electrons during treatment; a low-intensity pulsed current provides ES at approximately 10 μA, repeated 100 times per second. High-intensity pulsed current typically provides two short pulses (2–20 microseconds) at 100–500 V. It is a very safe current because its very short pulse duration prevents significant changes in both tissue pH and temperature.
Electrodes are usually placed over a wet conductive medium, in the wound bed, and on the skin a distance away from the wound. For a more bactericidal effect, one would use positive polarity to attract negatively charged neutrophils and macrophages. To encourage the development of granulation tissue, negative polarity would be used to attract positively charged fibroblasts. To stimulate wound resurfacing, use positive polarity to attract negatively charged epidermal cells. Patients are typically seen for 1 hour a day, 5 to 7 days per week. Documentation is critical.
Indications for ES in wound care include chronic wounds such as pressure ulcers, diabetic ulcers, and venous insufficiency ulcers. Contraindications include the presence of a cardiac pacemaker, malignancy, and placement of electrodes near the heart, along regions of the phrenic nerve, over the carotid sinus, over the laryngeal musculature, over topical substances containing metal ions, and over osteomyelitis.
However, many of the studies have demonstrated that when used in conjunction with standard wound management, ES can accelerate the healing rate of PrUs in patients with SCI.
Other Modalities and Adjunctive Therapies
Wound bed preparation is the primary purpose of cleaning wounds in order to promote wound healing. These include a series of debridement and treatment modalities intended to clean wound debris and necrotic tissue from the wound bed, and move the wound from the inflammatory to the proliferative phase of healing.
Hydrotherapy, including whirlpool and pulsed lavage, can be considered for PrUs containing large amounts of exudate and necrotic tissue, where it can assist in debridement. However, once the wound is clean and has healthy granulation tissue, the agitating water may cause damage to the delicate new tissue and should be discontinued, and other modalities are available to promote tissue proliferation such as e-stim, negative pressure wound therapy (NPWT), and the use of skin substitutes and growth factors. Other methods of debridement include conservative sharp, surgical, enzymatic, and biosurgical, or maggot debridement. Thus far, the efficacy of hyperbaric oxygen, infrared, ultraviolet, and low energy laser irradiation, and ultrasonography has not been established for recommendation in the treatment of PrUs.
Pressure ulcers remain a significant challenge to persons with SCI despite many advances in patient care and technology. Aggressive prevention and wound management strategies are integral to the patient’s rehabilitation. A thorough educational program can help those individuals learn how to take care of their bodies and prevent PrUs. If a pressure ulcer does occur, it is critically important to have access to a multidisciplinary team to assist in wound resolution and assist that individual back into the community. RM
Isa McClure, PT, MAPT, is a PT clinical specialist in spinal cord injury. She has worked at Kessler Institute for Rehabilitation since 1996 and chairs the Rehab Standards Committee of the American Spinal Injury Association.
Conchita Rader, RN, MA, CFCN, CWCN, has been the Wound Care Coordinator for Kessler Institute since 2010. She completed the wound care program at Emory University College of Medicine. Rader’s experience had been as a Clinical Nurse Specialist in Critical Care and in Medical-Surgical Nursing in an acute care facility. She developed the Wound Care Program at Kessler and has educated more than 230 wound care champions across the Acute Inpatient Rehabilitation Division of Select Medical, its parent company. For more information, contact RehabEditor@allied360.com.
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