CASE STUDY
Sickle cell disease is an autosomal recessive genetic disorder that affects the shape and function of red blood cells, causing a myriad of systemic complications. Rigid and deformed red blood cells can become trapped in the microvascular circulation, causing tissue ischemia and severe pain. This recurring pattern of vaso-occlusion and tissue ischemia can lead to dysfunction in all organs. Although acute chest and severe pain crises are the most common manifestations of sickle cell disease, skin ulcerations of the lower extremities also presents a unique challenge for many patients suffering from this condition (Ladizinski et al., 2012).
The exact pathophysiological cause of sickle cell leg ulcers is not fully understood, but it is thought to be a multifactorial process. Vaso-occlusion from sickle-shaped red blood cells resulting in a hypercoagulable state, endothelial dysfunction, chronic inflammation, and tissue ischemia is thought to cause the skin breakdown and chronicity of these ulcers (Altman, Kleinfelder, Quigley, Ennis, & Minniti, 2016). Sickle cell ulcers most often occur in the lower extremities where areas of thinner skin, with less subcutaneous fat and decreased blood flow, are more prevalent. Venous insufficiency may also play a role in the development of these ulcers, and these patients frequently benefit from compression therapy. Areas near the malleoli are most commonly affected, with the medial malleolus more commonly affected than the lateral malleolus. Up to 75% of patients with sickle cell disease struggle with these painful and debilitating ulcers. One of the hallmarks of these wounds is their high recurrence rate, with 80%-90% of wounds recurring within 2 years after wound closure (El Khatib & Hayek. 2016).
Sickle cell leg ulcers most commonly occur in male patients who are from low socioeconomic backgrounds and in the second and third decades of their lives. Lower extremity ulcers are also thought to be a marker of disease severity and are often associated with more severe complications such as pulmonary hypertension, acute chest, and priapism (El Khatib & Hayek, 2016). Although the cause of these ulcers and the quality of life associated with them may be different from other chronic wounds, the care is very similar. Nevertheless, it is important to remember that special considerations need to be made for the severe pain associated with sickle cell leg ulcers.
Management of chronic wounds is often guided by the DIME (or TIME) framework, which includes (tissue) debridement, infection and inflammation control, moisture balance, and epithelialization of the wound edges. Tissue debridement allows for removal of nonviable tissue and bacterial biofilm and is thought to be one of the most critical steps in promoting wound healing. Removal of nonviable tissue and biofilm decreases infection and inflammation, reduces exudate, which helps maintain moisture balance, and promotes reepithelialization (Chang, Perry, & Cross, 2017). Methods of debridement are vast and include autolytic, biosurgical, hydrosurgical, mechanical, surgical, ultrasonic, and conservative sharp debridement. Thorough assessment of each wound should be done to select the most appropriate method of debridement (Butcher & Pinnuck, 2013). The methods of choice, with regard to sickle cell leg ulcers, are most often autolytic, ultrasonic, and conservative sharp debridement.
Control of infection and inflammation, as well as achieving the appropriate moisture balance of chronic wounds, is almost as important in wound healing as debridement of nonviable tissue. Appropriate dressing selection is critical in reducing infection and inflammation and maintaining a moisture balance that promotes wound healing. Bacterial colonization is important to consider when choosing the dressing for a chronic wound. "Silver, iodine, honey, and polyhexamethylene biguanide dressings have antibacterial properties, and their use in chronic wounds has been documented to aid healing by reducing critical colonization," according to Ladizinski et al. (2012, p. 424).
In addition to the harmful effects of bacterial colonization, an excessively moist wound may damage the surrounding tissue, hindering wound epithelialization. In contrast, inadequate moisture may promote eschar formation, which can also impede wound healing. Foam dressings have absorptive properties and are ideal for wounds with high levels of exudate, whereas hydrogels can be used for hydration of dry wounds. Calcium alginates are bioresorbitive and convert to sodium alginate hydrogel and promote homeostasis, whereas films protect the wound but handle minimal exudate. Thousands of dressings are available for chronic wounds, making careful assessment of the wound and a thorough understanding of the DIME framework vital to wound healing.
L.N. was a 30-year-old man with a history of sickle cell disease who presented to the Wound Healing Clinic in August 2017 with recurrent bilateral medial malleoli wounds. These wounds were treated 3 years ago with debridement, compression therapy, and the skin substitute Integra, with eventual wound closure. The recurrent wounds were originally treated with conservative sharp debridement in the clinic. Home health support was arranged for every other day dressing changes with Santyl collagenase, Hydrofera Blue ready foam, and compression therapy. Santyl collagenase is a topical ointment that assists with autolytic debridement of the wound bed. The Hydrofera Blue dressing wicks excessive exudate and maintains a moist wound environment in addition to containing methylene blue and gentian violet for broad-spectrum antibacterial protection.
After a few months of stalled wound healing, it was decided to conduct weekly wound debridement with the Aerobella Qoustic Wound Therapy System. The Aerobella system uses ultrasonic waves to debride and cleanse the wound with saline or other wound cleansing solutions (Qoustic Wound Therapy System, 2015). According to Chang et al. (2017, p. 22), ultrasonic debridement is "thought to both debride the wound and promote healing by upregulating cellular activity, promoting growth factor (and protein) synthesis, promoting fibrinolysis, and disrupting the biofilm." The goal of ultrasonic debridement is to decrease fibrin slough and bacterial biofilm while promoting healing at the cellular level through the use of ultrasound waves. Although ultrasonic debridement typically should not be a painful treatment, it is well documented that sickle cell leg ulcers may cause severe pain. L.N. was treated with Lidocaine gel over all wounds for 10-15 minutes prior to treatment to reduce the discomfort associated with wound debridement. L.N. is now undergoing weekly ultrasonic debridements and continuing daily wound care with Hydrofera Blue ready foam and compression stockings. There is optimism among his care team that through wound bed optimization with ultrasonic debridement, antibacterial dressings, and compression therapy L.N. will once again achieve resolution of these chronic wounds.
Severe pain, a prolonged course, and high recurrence rate make sickle cell leg ulcers exceptionally difficult wounds to treat. Wound optimization through debridement, infection/inflammation control, and moisture balance are vital for eventual healing of these chronic wounds. Careful consideration of all dressings available as well as advances in debridement methods and tools to achieve wound bed optimization may benefit other patients with this type of recalcitrant wound.
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