Geometric framework reveals that a moderate protein, high carbohydrate intake is optimal for severe burn injury in mice.

Nutritional therapy is a cornerstone of burns management. The optimal macronutrient intake for wound healing after burn injury has not been identified, although high-energy, high-protein diets are favoured. The present study aimed to identify the optimal macronutrient intake for burn wound healing. The geometric framework (GF) was used to analyse wound healing after a 10 % total body surface area contact burn in mice ad libitum fed one of the eleven high-energy diets, varying in macronutrient composition with protein (P5-60 %), carbohydrate (C20-75 %) and fat (F20-75 %). In the GF study, the optimal ratio for wound healing was identified as a moderate-protein, high-carbohydrate diet with a protein:carbohydrate:fat (P:C:F) ratio of 1:4:2. High carbohydrate intake was associated with lower mortality, improved body weight and a beneficial pattern of body fat reserves. Protein intake was essential to prevent weight loss and mortality, but a protein intake target of about 7 kJ/d (about 15 % of energy intake) was identified, above which no further benefit was gained. High protein intake was associated with delayed wound healing and increased liver and spleen weight. As the GF study demonstrated that an initial very high protein intake prevented mortality, a very high-protein, moderate-carbohydrate diet (P40:C42:F18) was specifically designed. The dynamic diet study was also designed to combine and validate the benefits of an initial very high protein intake for mortality, and subsequent moderate protein, high carbohydrate intake for optimal wound healing. The dynamic feeding experiment showed switching from an initial very high-protein diet to the optimal moderate-protein, high-carbohydrate diet accelerated wound healing whilst preventing mortality and liver enlargement.

An investigation of early enteral nutrition provision in major burn patients in Australia and New Zealand.

AIMS: Early enteral nutrition (provided within 24 h of admission) is the optimal form of nutritional support for major burn injuries. The aim of this study was to (i) audit early enteral nutrition practices, (ii) identify characteristics of patients who received early enteral nutrition, and (iii) investigate whether early enteral nutrition was associated with in-hospital outcomes. METHODS: An analysis of prospectively collected data from the Burns Registry of Australia and New Zealand was conducted. Specifically, this study focused on major burns patients (defined as burns affecting more than 20% and 15% total body surface area for adult paediatric patients, respectively) admitted to a specialist burn service between 1 July 2016 and 30 June 2019. RESULTS: Data from 474 major burns patients (88 paediatric patients) revealed 69% received early enteral nutrition. Paediatric patients who received early enteral nutrition were younger than their counterparts who did not receive the same support (p = 0.04). Adult patients who received early enteral nutrition sustained larger burns (p < 0.001). Early enteral nutrition was not associated with in-hospital mortality following major burn injury in adult patients in either unadjusted (p = 0.77) or confounder-adjusted (p = 0.69) analyses. CONCLUSIONS: Approximately two-thirds of patients with major burn injuries received early enteral nutrition. Early enteral nutrition was not associated with in-hospital mortality following major burn injury. Further research should focus on modifiable reasons why major burns patients do not receive enteral nutrition within 24 h of admission.

Low-protein diet accelerates wound healing in mice post-acute injury.

BACKGROUND: Wound healing processes are influenced by macronutrient intake (protein, carbohydrate and fat). The most favourable diet for cutaneous wound healing is not known, although high-protein diets are currently favoured clinically. This experimental study investigates the optimal macronutrient balance for cutaneous wound healing using a mouse model and the Geometric Framework, a nutrient modelling method, capable of analyzing the individual and interactive effects of a wide spectrum of macronutrient intake. METHODS: Two adjacent and identical full-thickness skin excisions (1 cm2) were surgically created on the dorsal area of male C57BL/6 mice. Mice were then allocated to one of 12 high-energy diets that varied in protein, carbohydrate and fat content. In select diets, wound healing processes, cytokine expression, energy expenditure, body composition, muscle and fat reserves were assessed. RESULTS: Using the Geometric Framework, we show that a low-protein intake, coupled with a balanced intake of carbohydrate and fat is optimal for wound healing. Mice fed a low-protein diet progressed quickly through wound healing stages with favourable wound inflammatory cytokine expression and significantly accelerated collagen production. These local processes were associated with an increased early systemic inflammatory response and a higher overall energy expenditure, related to metabolic changes occurring in key macronutrient reserves in lean body mass and fat depots. CONCLUSIONS: The results suggest that a low-protein diet may have a greater potential to accelerate wound healing than the current clinically used high-protein diets.

Dysphagia in older persons following severe burns: Burn location is irrelevant to risk of dysphagia and its complications in patients over 75 years.

BACKGROUND: Management of burns in older persons is complex with evidence indicating advanced age is associated with elevated risk for morbidity and mortality. Dysphagia and its sequelae may further increase this risk. AIMS: (1) Determine the prevalence, and (2) identify risk factors for dysphagia in patients admitted with severe burn injury over 75 years. METHODS: All patients >75 years admitted to Concord Repatriation General Hospital with severe burn injury over a 4-year period (2013-2017) were assessed for dysphagia on presentation and continually monitored throughout their admission. Burn injury, demographic and nutritional data were captured and analysed for association with and predictive value for dysphagia. RESULTS: Sixty-six patients (35 male; 31 female) aged 75-96 years (median 82 years) were recruited. Dysphagia was identified in 46.97% during their hospital admission. Dysphagia was significantly associated with burn size, pre-existing cognitive impairment, mechanical ventilation, duration of enteral feeding, hospital length of stay, in-hospital complications and mortality. No association was identified between burn location, burn mechanism, surgery and dysphagia. Burn size and Malnutrition Screening Tool score were found to be independent predictors for dysphagia. CONCLUSIONS: Dysphagia prevalence is high in older persons with burns and is associated with increased morbidity and mortality, regardless of burn location.

The Effects of Dietary Macronutrient Balance on Skin Structure in Aging Male and Female Mice.

Nutrition influences skin structure; however, a systematic investigation into how energy and macronutrients (protein, carbohydrate and fat) affects the skin has yet to be conducted. We evaluated the associations between macronutrients, energy intake and skin structure in mice fed 25 experimental diets and a control diet for 15 months using the Geometric Framework, a novel method of nutritional analysis. Skin structure was associated with the ratio of dietary macronutrients eaten, not energy intake, and the nature of the effect differed between the sexes. In males, skin structure was primarily associated with protein intake, whereas in females carbohydrate intake was the primary correlate. In both sexes, the dermis and subcutaneous fat thicknesses were inversely proportional. Subcutaneous fat thickness varied positively with fat intake, due to enlarged adipocytes rather than increased adipocyte number. We therefore demonstrated clear interactions between skin structure and macronutrient intakes, with the associations being sex-specific and dependent on dietary macronutrient balance.