Wound care

A wound can be defined as a cut or break in the continuity of the skin caused by injury or operation¹.  Wounds represent a major burden in terms of morbidity and reduced quality of life for patients².  Living with a chronic wound can cause pain, discomfort, sleep disturbance, depression and reduced social interaction².  The care of wounds places significant financial burden on the healthcare system, with the total healthcare costs of wound care in Ireland estimated to be €789million per year³.

Acute wounds usually heal in an ordered, timely fashion and are typically traumatic or surgical in nature⁴. 

A chronic wound does not heal in an orderly set of stages and has a prolonged healing time. These wounds cause patients severe emotional and physical stress as well as creating a significant financial burden on patients and the whole healthcare system². Venous ulcers, arterial ulcers, diabetic foot ulcers and pressure ulcers are examples of chronic wounds⁴.

It is estimated that 1.5% of the population worldwide are affected by a wound at any point in time¹. There is evidence that the burden of chronic wounds such as pressure ulcers in Ireland is already high, with a prevalence of 4% identified in one study on the active caseload of community nurses⁵. Due to the aging population, the prevalence of wounds is likely to increase in Ireland¹.

The wound healing response can be divided into three sequential but overlapping phases⁴:

1. Inflammatory phase
2. Proliferation phase
3. Maturation and remodelling phase

The first stage of wound healing involves vasoconstriction, as the body attempts to control bleeding from the injured site. Platelets gather at the site, and a clot is formed. 

The proliferation phase involves the formation of new tissue such as collagen and can last several weeks. Granulation occurs, with increased cellular activity, leading to increased requirements for specific nutrients. If these needs are not met, there can be a significant impact on wound healing. 

The process of maturation and remodelling can last for up to two years. More collagen and blood vessels are created, and eventually scar tissue will form.

The duration of wounds is directly related to prolonged healing rates. Clinicians should consider all factors that enhance or impede the wound healing process in the development of the plan of care¹.

The management of wounds involves a multi-faceted approach, to include adequate wound bed preparation, appropriate use of dressings, management of the underlying disease, and correction of factors which impair wound healing.

Optimum wound healing requires adequate nutrition. Nutritional deficiencies impede the normal processes that allow progression through the stages of wound healing⁴. Poor nutritional status can be a cause of wound development, for example, patients with poor dietary intake and low body weight have been shown to be at increased risk of pressure ulcer development⁶.

The role of nutrition in wound management includes:

• the correction of malnutrition and
• the correction of nutrient deficiencies, particularly those which have been shown to have a direct impact on the rate of wound healing

Research shows that malnutrition negatively affects the wound healing process. Nutrient deficiencies can prolong the inflammatory phase by decreasing the proliferation of fibroblasts and formation of collagen as well as reducing tensile strength and angiogenesis⁷. A 2005 meta-analysis by Stratton et al⁸ showed that the provision of oral nutritional supplements (250-500kcal per serving) given over a period of 2 to 26 weeks was related to a significantly lower incidence of pressure ulcer development compared with standard care.

Nutritional screening of all patients at risk of chronic wounds is recommended in order to prevent complications of malnutrition¹. MUST (Malnutrition Universal Screening Tool) is a universally accepted valid and reliable screening tool that can be used in all care settings and has been recommended by the European and National Pressure Ulcer Advisory Panels (EPUAP & NPUAP)⁹ and the HSE National Wound Management Guidelines 2018¹. 

Wound nutrition is essentially whole-body nutrition and the goal is to maintain body mass, limit weight loss and provide adequate nutrients to promote healing. Nutritional intake should be varied and balanced to provide all the essential nutrients.

A significant number of studies have investigated the potential value of specific nutrients in regulating wound healing as follows:

EPUAP & NPUAP⁹ & the HSE¹ recommends a minimum of 30-35kcal per kg body weight per day as a general guideline for patients with pressure ulcers. 

This must be assessed and adjusted based on weight loss and level of obesity. Patients who have lost weight may require additional calories, while patients with obesity should have their caloric goals adjusted appropriately¹⁰.

Protein is necessary for the synthesis of enzymes involved in wound healing, proliferation of cells and collagen, immune function and the formation of connective tissue. Inadequate protein intake, often in conjunction with excessive losses of protein via wounds exudate, can lead to protein deficiency¹. 

The recommended intake of protein associated with wound healing 1.25-1.5g/kg body weight/day for individuals with chronic wounds¹⁰. If the patient is severely catabolic, with more than one wound, or with a stage III or IV pressure ulcer, they may require 1.5-2g/kg body weight/day (monitoring of hydration status and renal function recommended)^1,10.

Arginine is a conditionally-essential amino acid that contributes to wound collagen synthesis.  As a donor of nitric oxide, it can also increase tissue blood flow and improve immune response¹¹.

There is no conclusive evidence to support the independent effect of arginine; however there is on-going evidence that it can significantly improve the rate of healing in pressure ulcers when used as part of an enriched nutrient formula^11,12,13,14. 

The HSE wound management guidelines recommend providing adequate water intake to aid blood flow to healthy and healing tissue¹.

Many different vitamins, minerals and trace elements are required for normal health and physiological function. Vitamin C, A, zinc and iron are particularly important in wound healing¹⁰:

Vitamin C (ascorbic acid) functions in the synthesis of collagen and as an antioxidant. Vitamin C deficiency results in an impaired immune response and increases the risk of wound dehiscence¹. 

Vitamin A has an anti-inflammatory effect in wounds. Deficiency of vitamin A results in impaired collagen synthesis and reduced immune function⁷.

Zinc is a trace element, present in small amounts in the body. Zinc plays a key role in protein synthesis and in tissue growth and healing. Zinc deficiency has been associated with delayed wound healing, reduced skin cell production and reduced immune system function¹¹. The potential role of zinc supplementation in wound healing has been investigated; healing appears to be accelerated only in patients with low serum zinc levels. Zinc supplementation is recommended only in the presence of zinc deficiency, which is commonly seen in patients who have, or are at risk of, malnutrition, diarrhoea or  malabsorption¹.

Iron is a co-factor in hydroxylation of lysine & proline for collagen synthesis. It is required for oxygen transport and it is a component of many enzymes required for wound healing. Low haemoglobin concentration due to iron deficiency may be a factor in tissue hypoxia, impaired hydroxylation of collagen and reduced immune response¹⁰.

Other nutrients which have important functions in association with wound healing include vitamin E, vitamin K, vitamin B complex, copper, manganese, chromium and essential fatty acids. Poor nutrition leading to nutrient deficiencies will interfere with wound healing, mostly by delaying the healing response. Evaluation of a patient's nutritional status through assessment and the provision of a nutritionally appropriate diet is one of the first principles to healing¹⁰.

As outlined above, there are several nutrients which play an important role in wound healing. Previous trials were not able to demonstrate a positive effect for single micronutrients in wound healing, which may have been related to the failure to provide enough energy alongside the supplementation¹¹.

Previous trials were not able to demonstrate a positive effect for these single micronutrients and the failure was likely due to the lack of concomitant energy supply”. However, research has shown that 8 weeks supplementation with an oral nutritional formula enriched with arginine, zinc and antioxidants improved pressure ulcer healing when compared with controls¹³. Latest International and HSE wound healing guidelines have recommended considering providing a supplement that contains high protein, arginine and micronutrients for adults who are malnourished with a pressure ulcer stage II, III or IV or multiple ulcers for at least 8 weeks.^9-11.

There is also evidence to support a role for arginine, zinc and antioxidants enriched oral nutritional supplements in the healing of diabetic foot ulcers, and leg ulcers¹⁴. 

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