Arginine & Immune Status in Elderly with Pressure Ulcers
Objective: Elderly subjects with pressure ulcers are a particularly vulnerable population due to increased incidence of infection and prolonged healing times associated with aging. Treatments that improve immune function and ultimately wound healing would increase quality of life for the elderly and decrease costly additional interventions. The amino acid arginine enhances immune function and the healing of artificial wounds in healthy adult populations, but no studies have examined its effect among elderly nursing home residents with pressure ulcers. The purpose of this study is to determine the effect of arginine supplementation on in vivo and in vitro immune parameters in nursing home elders with pressure ulcers and to examine the role of nitric oxide in arginine-modulated immune function. One mechanism by which arginine modulates immune function is by serving as a substrate for nitric oxide production. Nitric oxide, which is important in bacterial killing, inhibits lymphocyte proliferation and may be responsible for the attenuated proliferation response observed in our preliminary studies in the nursing home residents with pressure ulcers who received 8.5 or 17 g of supplemental arginine per day. Design: Experimental double-blinded. Sample: In the proposed study nursing home residents (> 65 years of age) with one or more pressure ulcers will be randomized to one of two groups (n=15 per group). Methods: One group will receive 8.5 g of supplemental arginine and the other group will receive an isonitrogenous amount of a standard protein powder mixed in cherry syrup for 4 weeks. Variables Studied: Immune function will be measured by assessing mitrogen-induced lymphocyte proliferation, cytokine production, neutrophil oxidative burst and CD44/CD45 expression, delayed type hypersensitivity, and incidence of infection prior to supplementation (baseline), 4 weeks post supplementation and after a washout period (10 weeks post-supplementation). Nitric oxide production will be measured in the presence and absence of a nitric oxide inhibitor in stimulated lymphocyte cultures. Nutritional status will also be assessed at baseline, week 4, and week 10. Interactions between general nutritional status and immune function will be identified. Data will be analyzed using multivariate methods. Findings: Study currently in progress. Implications: This research will provide a basis for a larger study to examine the effect of arginine on healing of pressure ulcers controlling for location and stage of the ulcer. Further, it will contribute to a program of research focused on evaluating the role of nutritional supplementation in preventing or treating pressure ulcers in elderly populations.
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