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Good eating can improve healing

Improved nutrition has a major role to play in the prevention and treatment of pressure injuries, write Beryl Dawson, Susan Nelan, Katrina Pace and Lilliana Barone.

Pressure injuries can range from small red areas of damage to deep, full tissue thickness wounds and can be painful, debilitating and costly to treat.

While pressure injuries can occur in anyone, there is a typically higher incidence rate in older people and those with less mobility, including those with spinal cord injuries. This is due, in part, to a reduction in both muscle mass and mobility.

The risk of pressure injuries increases regardless of age if an individual is bed or wheelchair bound, and is frequently found in association with a chronic disease such as chronic obstructive airway disease, which may reduce mobility, affect circulation or reduce nutrition. An increasing number of morbidly obese people are presenting with pressure areas due to poor circulation, skin friction and other metabolic conditions associated with excess weight.

Malnutrition has been shown to be an independent risk factor for the development of pressure injuries. In fact, it has been estimated by Merrilyn Banks and Nicholas Graves that 33 per cent of pressure injuries seen in public hospitals can be attributed to malnutrition. Whilst improved nutrition has been shown to have a major role in the healing or treatment of pressure injuries, it is frequently overlooked.

Recent Australian data estimates the mean economic cost of pressure injuries due to malnutrition in acute care facilities to be in excess of $12 million. Nutrition is implicated in the immune response initiated by the body to reduce infection, as well as the provision of nutrients to build new tissue and optimise circulation to the wound site.

The use of a validated nutritional screening tool can be used by nursing staff to assist in identifying those individuals needing more in-depth nutritional assessment. Examples include:
• The Mini Nutritional Assessment short form (MNA-SF, for use in the older person)
• Malnutrition Screening Tool (MST) or
• Malnutrition Universal Screening Tool (MUST).

An accredited practising dietitian (APD) can help determine the best screening tool, and assist in developing implementation strategies.

Nursing staff, having documented and staged all wounds and pressure injuries on and during admission, should refer to an accredited practicing dietitian as required. A dietician will provide a detailed nutritional assessment to determine energy, protein and micronutrient intake and needs to ensure nutritional status is maximised to facilitate healing whilst minimise muscle wastage.

A detailed nutritional assessment will also consider the presence of other conditions that may affect nutrient requirements – such as infection, malabsorption, and chronic conditions such as diabetes or obesity.

Why worry about what is eaten?

Nutrition is implicated in the immune response initiated by the body to reduce infection as well as the provision of nutrients to build new tissue and optimise circulation to the wound site. Without an adequate intake of essential amino acids, the body begins to break down muscle to obtain the amino acids required for wound healing. The amino acids arginine and glutamine are both considered conditionally essential and studies have shown these enhance healing when supplementary amounts are consumed.

The nutrient requirements to heal a small stage 1 pressure injury differ considerably to the requirements of those needed to heal a necrotic stage 4 (severe) pressure injury, as would those of non-exudating versus highly-exudating wounds. These issues, as well as the varying nutrient requirements at different stages of the wound healing process, make nutritional review and monitoring essential. While underweight or bed-bound patients are easily identified as being at increased risk of pressure injuries, those overweight or “well-nourished” on a background of poor intake can also be at high risk of slow healing if protein intake is inadequate.

How to maximise healing

Providing adequate protein (or perhaps more accurately, good quality protein), vitamin A, iron, zinc and vitamin C, are essential for wound healing, as is adequate hydration. Poorly controlled diabetes will also delay wound healing. Meal plans must be individualised and meal assistance provided as needed. This may be as simple as opening packets of food or drink, or ensuring that tables are cleared, or may involve more substantial assistance such as full feeding assistance, or require an organisational change to ensure protected meal times.

Protein needs are increased for all stages of pressure injuries with up to 2g per patient kg for exudating wounds, or wounds that require more frequent dressing changes. Providing greater than 2g/kg of protein is unlikely to provide additional benefit and may negatively impact on hydration status, which in itself will delay healing.

The best sources of protein are animal-based foods (such as eggs, milk, whey protein isolate, fish, meats and soy products). Good between-meal snacks include milk-based custards and yoghurts, nuts, and oral nutritional drinks as recommended by a dietitian. Encourage high-quality protein at all meals. This can be as simple as adding a glass of milk or carton of yoghurt to a meal.

Energy needs must be individualised as determined by clinical status, and diabetic meal plans are best based on low glycaemic index foods to assist with blood glucose control.

Vitamin D has been shown to be important for immune system functioning. Most foods are poor sources of Vitamin D and as direct sunshine is needed for the production of Vitamin D, anyone termed “house bound” (regardless of age), or those who wear full-length clothing (especially all year round) will likely be deficient. In regard to other vitamins and minerals, studies have shown that once other micronutrients, such as iron and zinc, are replete no further benefit is achieved by giving more.

Evidence shows that aggressive nutritional support in the form of alternative feeding (via a nasogastric tube or PEG) may be considered if dietary intake remains sub-optimal despite the modification of meals and the use of oral nutrition support. A dietitian can recommend the most appropriate form of nutrition support.

Dietitians and nurses working together
The frequency of monitoring and parameters for monitoring may be affected by many issues, such as:
• Wound status (stage of pressure injury, exudate, presence of infection)
• Underlying disease conditions
• Availability of equipment
• Test results (including the presence of abnormal results)
• Clinical setting, and
• Availability of staff

Adequate hydration is essential for wound healing. Those requiring modified thickened fluids, with poorly controlled diabetes, on diuretic therapy, or with prolonged fevers are at risk of dehydration. Food and fluid charts along with bowel charts provide an extremely useful tool for assessing adequacy of intake. If food intake is regularly less than 75 per cent of most meals, notify the dietician for review and encourage consumption of the protein component of the meal rather than starchy fillers.

Weighing the patient - daily or weekly - allows assessment of possible over or under hydration as well as a measure of intervention when interpreted in conjunction with the food and fluid charts.

Simple yet effective monitoring should include:
• Regularly documented and reviewed food and fluid intake charts
• Bowel charts (as constipation may signal dehydration)
• Regular blood glucose monitoring for people with diabetes
• Weekly weights – or daily if over hydration is an issue.

Beryl Dawson, Susan Nelan, Katrina Pace and Lilliana Barone are all are members of the Dietitians Association of Australia or Dietitians New Zealand and the Trans-Tasman Dietetic Wound Care Group. The evidence-based practice guidelines for the dietetic management of adults with pressure injuries were released in September 2011. Guidelines and resources can be accessed from: www.ttdwcg.org . References are available upon request.

Practice points:
• Use a validated nutritional screening tool for those at risk of pressure injuries
• Document all pressure injuries and refer all wounds stage 2 and above for dietetic assessment
• Take weight on admission and then weekly if possible
• Document sites of oedema

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