A DEFICIENCY in vital nutrients may delay wound healing. Research supports the importance of protein, vitamin C and zinc in wound healing. Chronic wound healing requires a multidisciplinary and holistic approach. Early identification of at-risk patients is vital for the prevention and exacerbation of pressure sore development.
Wound healing involves complex physico-chemical interactions that require various micro and macronutrients at every stage. The prevalence of pressure ulcers among hospitalised patients ranges from 3%-11% and 18% among bedridden hospitalised patients.
The relationship between malnutrition and pressure sore development is well documented. Clinical manifestations of malnutrition include weight loss and compromised immune function. Both underweight and obese individuals can be malnourished.
A high incidence of weight loss, low body mass index, malnutrition and poor visceral protein status are reported nutritional factors associated with pressure ulcer development in long-term care patients.
A primary objective for healthcare professionals should be to recognise the risk factors for undernutrition in such patients and to try to maximise their nutritional status if possible.
Micro and macro-nutrients
It is essential to provide adequate energy to meet the patients nutritional requirements and prevent depletion and/or utilisation of fats and protein stores.
Hyperglycaemia associated with sepsis and poorly controlled blood sugars is known to increase the incidence of infection, thus impeding the wound-healing rate. Monitoring glucose levels and taking measures to treat hyperglycaemia by dietary means and/or medical intervention are therefore essential for pressure ulcer management.
Protein depletion adversely affects healing. Sufficient dietary protein optimises the rate of wound healing. A wound may lose up 90g-100g protein, via the exudate per day, thus protein requirements in these patients may be twice the normal protein requirement. Specific amINO acids including arginine are known to play a role in wound healing.
Hypoalbuminaemia is reported to be significantly related to the incidence of pressure sores and may predict poor wound healing. Studies report that patients with stage IV ulcers are the most malnourished and have the lowest serum albumin levels. However, it is important to note that the albumin level is not a specific marker of nutritional status since serum albumin can be reduced in a variety of disease states and injury, independent of the patients nutritional status.
Zinc plays a central role in the enzyme-catalysed reactions of protein synthesis. Zinc deficiency inhibits wound healing by reducing the rate of epithelialisation and cellular proliferation, thus impairing wound strength. Supplementation with zinc reverses these defects and enhances wound repair in individuals who are already biochemically zinc deficient. Patients with poor wound healing and normal zinc levels show no improvement with zinc supplementation. Checking biochemical levels pre-supplementation is therefore ideal.
Recommended daily allowance ranges between 7mg-9.5mg/daily. While general supplementation with 200mg-220mg/zinc sulphate (50mg elemental zinc) daily is recommended. Zinc is found in seafood, meats, liver, milk, eggs, wheat germ and whole wheat bread.
Low haemoglobin (Hb) levels are associated with pressure ulcer development and delayed wound healing due to reduced oxygen content in the tissues. A report by the National Health and Nutrition Examination Survey 1980, concluded that individuals with haemoglobin less than 12gm/dL were more than twice as likely to develop pressure ulcers than those with haemoglobin greater than 12gm/dL, prompting correction of anaemia and monitoring of Hb levels to optimise wound healing.
Patients at risk of
developing pressure ulcers
A healthy adult male requires 10mg daily while a healthy female requires 14mg daily. Good sources of iron include red lean meat, liver, poultry, beans, lentils, sardines, green leafy vegetables and fortified cereals. Foods high in vitamin C are known to enhance non-haem iron absorption, while high quantities of tannins (eg. tea) and phytates found in bran are known to reduce non-haem iron absorption.
Vitamin C (Ascorbic Acid) is an essential co-factor for the enzymes prolyl and lysyl hydroxylase, which function to hydroxylate proline and lysine in collagen. Patients with severe illnesses or injuries can rapidly become vitamin C depleted since the water-soluble vitamin cannot be stored in large amounts in the body. Studies report the amount of vitamin C required during wound healing ranges from 100mg-300mg/daily, equivalent to one-four servings of citrus fruits per day. Higher intakes 1g-2g per day have also been recommended until full recovery. Good vitamin C sources include green vegetables, potatoes, tomatoes and citrus fruits including oranges, lemons and grapefruit.
B Group Vitamins
Components of the B vitamin group are coenzymes in energy-generating reactions necessary for energy metabolism. B vitamins are essential for optimum wound healing including, thiamine (B1), riboflavin (B2), pyridoxine (B6) and pantothenic acid (B5) in particular. B vitamins are found in cereals, wheat germ, whole-grain breads, pasta, and fortified foods.
Patients consuming poor dietary intakes are at high risk of developing micro and macronutrients deficiencies. Supplementation with such nutrients may be warranted, based on individual assessment. Vitamin/mineral supplementation may be indicated based on individual dietary assessment. However, over supplementation of any one mineral should be avoided, since this may affect absorptive and/or metabolic interactions.
Nutritional support in the nutritionally compromised patient is an essential part of ensuring efficient wound healing in these patients. If a patients oral intake remains inadequate to meet estimated nutritional requirements, supplemental enteral feeding may be indicated.
Rosalyn Tarrant is a senior clinical nutritionist at St James's Hospital
References in request