Specific nutrients in wound healing Flashcards
What are the nutrients that are critical to the wound healing process?
Energy, protein, arginine, water, Vit A,C,E and minerals.
Note: optimal nutrient and energy intake to promote wound healing is unknown.
Adequate energy needs is essential for optimal wound healing, specifically for cell metabolism, anabolism, collagen formation, nitrogen retention, and angiogenesis (development of bld vessels).
Est energy needs shld be individualized based on age, comorbidities, body wt, activity level, severity and # of wounds, size of wound(s), stg in the healing process, nutritional state, basal met rate, and level of physiological stress.
Examples:
1. Energy requirements for wound healing in geriatric pts
Energy Requirements cont’d:
Although recommended energy req amts for optimal wound healing are not known, AHCPR (pg 409) recommends 30-35g/kg. For underweight or individuals w/ unintentional wt lost, NPUAP (pg 409) recommends ↑ing energy goals to 35 - 40g/kg to enhance wound healing.
When available, indirect calorimetry is recommended to identify more closely individual energy needs for pts who: a) fail to achieve anabolism;
b) Exhibit delayed wound healing;
c) May require more energy to assist in healing larger or multiple wounds.
d) Present a need for a more aggressive approach to the nutrition care plan.
Note: CHO and fat is a good source of energy but excess CHO intake can be a problem for diabetics and cause fatty liver and ↑ing CO2 prod particularly in pts on EN or PN.
PRO Req in Wound healing
PRO is a required structural component for skin integrity, for growth and maintenance of cells, and for fluid and electrolytes balance. PRO plays an essential role in fibroblast proliferation, collagen production, and angiogenesis, all of which are necessary for wound healing.
PCM, a condition assoc w/ inadequate PRO and Kcal intake, unintentional wt loss or low body wt for ht, results in delayed wound healing as per studies.
When addressing PRO needs, take into consideration PRO losses from wounds/pressure ulcer and also the #, size and depth of them.
What is the RDA for PRO in healthy adults and older adults (>65 yrs)?
What is National Pressure Ulcer Advisory Panel (NPUAP) PRO recommendation for individuals with pressure ulcers?
- .8g pro/kg for healthy adults
- 1g pro/kg for older healthy adults because they have increased pro requirements to maintain a + nitrogen balance.
- 1.25 - 1.5gpro/kg body wt
Arginine
Arginine is a semi-essential a.a produced in the body for cellular metbolism. During stress, endogenous stores are depleted, and supplemental sources are recommended. Arginine is found in dietary supplemens, in the diet and in EN fomulations. Arginine has been used to promote PRO synthesis, cells signaling through nitric oxide prod, stimulation of immune function, and cell proliferation through metabolism of ornithine and polyamines. Studies have shown enhanced wound strength and collagen deposition in artifical incisional wounds.
However, studies have not focus on chronic wounds, and the ability to enhance healing of delayed chronic wounds. Recommendations for a safe regimen of arginine supplementation in humans w/ wounds have not been determined, and controversy exists. In critical ill pts, studies suggest that arginine supplementation could result in excessive nitric oxide prod, an enhance systemic inflammatory response and hemodynamic instability in pts w/ sepsis. However, others say the benefits outweighs these potential risks. It depends on the clinician to perform a risk-benefit analysis to determine the use of arginine in critical ill pts.
HMB and wound healing
In theory, beta-hydroxy-beta-methylbutyrate (HMB), a metabolite of leucine, may increase collagen formation, modulate protein utilization, and inhibit muscle breakdown. 3g of HMB along w/ 14g arginine and 14g glutamine have shown results of increased collagen deposition.
Glutamine and wound healing
Glutamine is a fuel source for enterocytes, lymphocytes, fibroblasts, epithelial cells, and macrophages. Also a plays an important role in wound healing. Research indicates, but not confirm, that glutamine supplementation can enhance immune function in elective surgery and in catabolic states. Max recommendation for glutamine supplementation dose: .57g/kg/day.
Fat and wound healing
Given the inconsistencies reported in the literature regarding the effects of free fatty acids and wound healing, clinicians should exercise caution w/ supplementation of fatty acids in individuals w/ delayed wound healing.
Hydration and wound healing
Adequate hydration contributes to good skin turgor, perfusion, and oxygenation of healthy and wounded tissues. Also, maintaining normal fluid status is an important factor in prevention and treatment of skin breakdown.
Dehydration, on the other hand, impairs O2 delivery to the wounded tissues. O2 is necessary for hydroxylation of lysine and proline during the formation of collagen. Research indicates that in a state of hypoxia, a decrease in healing of acute wounds occurs.
Hydration and wounds healing
What are two general guidelines for daily fluid intake?
30ml/kg and 1 - 1.5ml/kcal consumed.
Conditions that requires careful monitoring of fluid states are: evaporation of fluids from severe pressure ulcers, draining wounds, open wounds, persistent diarrhea and/or vomiting, diuresis, fever, sweating, mechanical ventilation, and other causes of fluid losses.
Vit A and wound healing
Vit A performs a # of functions in wound healing (although the precise mech of action is unknown):
1. Acts as a stimulant of the immune system
2. May be important during the inflammatory phase of wound healing by increasing the # of macrophages and monocytes in wound environment.
3. Maintains the integrity of mucosal and epithelial surfaces.
4. Enhances collagen formation
Vit A and wound healing
- Inhibits the detrimental effects of glucosteriods, chemotherapy, radiation, DM and excessive Vit E supplementation on wound healing.
- Deficiency results in impaired wound healing and alterations in immune function that may increase the likelihood of wound infections.
Vit A and wound healing
The recommendation for Vit A is 3000IU (International units) and 2300IU for men and women, respectively. However, doses of 10,000 to 50,000IU for 1wk to 10 days to prevent toxicity, have been documented in research to enhance wound healing and to counteract the anti-inflammatory effects of steroid therapy and immune suppression.
Vit A and wound healing
Pts w/ abnormal liver function or malnutrition needs special attention because toxicity may occur in this group; Vit A is stored in the liver and relies on protein for transport.
Also, renal failure places pts at high risk for vit A toxcity.
The use of serum levels to monitor toxicities/def is no longer recommended bcuz other conditions (infection,malnutrition etc) may alter vit A conc. An alternate method is an indirect relative dose response test in which liver Vit K stores are est by obtaining a serum retinol conc ac/pc a small dose of oral retinol. A 20% ↑ over baseline of retinol reflects adequate body stores of Vit A.
Vit C and wound healing
Vit C enhance wound healing by:
1. Function as a cofactor in the hydroxylation of proline and lysine in collagen formation.
2. Vit C is required for angiogenesis and fibroblast formation.
3. It acts on the immune function, specifically on neutrophil activity, which aids in preventing wound infections.
4. Vit C def has been associated with delayed wound healing.
Vit C and wound healing
- Vit C is not readily stored in the body, poor dietary intake and malnutrition decrease levels of Vit C over time, resulting in deficiency.
- People who are at risk for Vit C def are drug abusers, alcoholics, those medically stressed and/or severely injured, and the elderly.
Vit C and wound healing.
- Minimal vit C requirements to prevent scurvy is 10 - 20mg/day but current recommendation are 75mg/day and 90mg/day for women and men, respectively. Since smoking increases oxidative stress and Vit C turnover, smokers require an additional 35mg/day.
- In pts w/ vit C def, supplementation has been shown to enhance wound healing, but a similar effect has not been demonstrated in those who have adequate levels of the vitamin.
According to the Agency for Health Care Research and Quality (AHRQ) guidelines, recommendations for pts w/ vit deficiences should receive a Vit and mineral supplement containing up to 10x the recommend dietary allowance to a water soluble vit. This translate to 100 - 200mg/day of vit C for stg 1 or II and more aggressive supplementation of 1000- 2000mg for stg III or IV pressure ulcer, or highly stress, malnourished, cigarette smokers, and seriously injured pts.
What condition should caution high doses of Vit C supplementation?
Renal failure. In these pt, current guidelines recommend giving no more than 60 - 100mg/day of Vit C due to the risk of renal oxalate stone formation.
- When administering high doses of Vit C, care monitoring of adverse effects should be considered, including GI disturbances (bloating and cramping, diarrhea and nausea) and antioxidative effects.
Vit E and wound healing
Vit E is an antioxidant. Its effect in wound (acute and chronic) healing is controversial. Some speculation suggest that the antioxidant properties of Vit E may play a role during the inflammatory phase of wound healing. However, many individuals take supplemental vit E above the DRI for health benefits as an antioxidant; this has been shown to inhibit collagen formation and to decrease the tensile strength of acute surgical wounds resulting in delayed wound healing.
In addition, patients taking an excessive amounts of vit E supplements have experienced delayed wound healing. Before recommendations for Vit E supplementation can be made, further research is needed in humans using controlled randomized trials to determine risk and benefits of various doses of Vit E and the effects on wound healing.
