Annals of Burns and Fire Disasters - vol. XIV - n. 4 - December 2001

THE EFFECTIVENESS OF EARLY ENTERAL NUTRITION IN BURN PATIENTS

Marvaki C.,¹ Joannovich I.,² Kiritsi E.,¹ Iordanou P.,¹ Iconomou T.²

¹ T.E.I Nursing Department, Athens, Greece
² Department of Plastic Surgery, Microsurgery and Burn Centre, G. Gennimatas General State Hospital, Athens

SUMMARY. This study was performed in order to investigate the effectiveness of early enteral nutrition (EEN) in burn patients, in association with their post-burn nutritional state and immunological response. Patients with burns in more than 25% of the total body surface area (TBSA) admitted to the Department of Plastic Surgery and Burn Unit of the General State Hospital of Athens over a three-year period were included in our study. A nutritional support protocol was followed that included EEN in the first 6 h via a nasogastric tube and administration of nutritional formulas of different nutritional value, according to each patient’s needs and tolerance. We administered to our patients: 1) low kcal value, 0.5 kcal/ml with 2 g/%; 2) standard value, 1 kcal/ml with 4 g/%; 3) high kcal value, 1.5 kcal/ml with 6 g/%. The following markers were used to assess the effectiveness of EEN: total serum proteins, serum albumin, serum globulin, absolute number of lymphocytes, immunoglobulin IgA, IgM, IgG, serum iron, and total iron binding capacity (TIBC). Blood samples were collected from each patient on days 1, 8, and 15 after admission for the measurement of the nutritional markers. Data were collected on a specially designed assessment chart. This was followed by statistical analysis for evaluation of the results. Thirty-one patients (age range 17-95 yr, mean 43.7 ± 12.2 yr; TBSA burn range, 25-85%, mean 43.4 ± 18.67%) were studied. All mean protein values increased significantly between the first and third measurements: total proteins increased from 5.06 to 6.33 mg/dl (p < 0.001); serum albumin from 2.97 to 3.40 mg/dl (p < 0.005); serum globulin from 2.06 to 2.91 mg/dl (p < 0.001); iron from 34.56 to 48.44 mg/l (p < 0.008); and TIBC from 84.80 to 120.60 mg/l (p < 0.001). There were no significant changes in the absolute number of lymphocytes or in immunoglobulin IgA, IgM, IgG. Our results demonstrated that early enteral nutrition provided optimal preservation of the patients’ nutritional state and maintained nutritional markers at normal values.

Introduction

Severe burn injury is characterized by a marked hypermetabolic response and hypermetabolism and even more markedly by loss of lean body mass.1-3 This hypermetabolic response is accompanied by a progressive decline of host defences, by immunological abnormalities, and by a marked decline in the number of circulating T lymphocytes, all of which impair survival.4,5 Aggressive nutritional support to meet the increased energy expenditure has been considered essential for the management of burn patients.6,7 Early enteral nutrition (EEN) has been considered an essential part of post-burn management to minimize the catabolic loss and enhance the immunological response.5-8 It has been shown to be an effective additional measure in stress, ulcer prophylaxis, and the prevention of sepsis.9-14

The purpose of our study was to evaluate the effectiveness of EEN in burn patients, in association with their post-burn nutritional state and their immunological response.

Material and methods

Patients with burns in more than 25% total body surface area (TBSA) admitted over the last three years to the Department of Plastic Surgery and Burn Unit of the General State

Hospital of Athens, Greece, were included in our study. Inclusion and exclusion criteria were used in the selection of the patients. Inclusion criteria were age (Ž 17 yr) and the extent of the burn injury. Exclusion criteria included the following: 1. patients in palliative care; 2. previous or planned surgical operation; 3. patients with sepsis; 4. patients presenting allergies to enteral fluids. The data were collected using an assessment chart. The hospital’s ethical committee approved the study, and all patients selected gave their consent. A nutritional support protocol was followed in all patients which included EEN, starting in the first 6 h after admission and lasting until complete healing of the burn injuries. Solutions of different nutritional value were administered via a nasogastric feeding tube according to the patients’ energy requirements and gastrointestinal tolerance. The enteral nutrition formulas used were: 1. low kcal value, 0.5 kcal/ml with 2 g/%; 2. standard value 1 kcal/ml with 4 g/%; 3. high kcal value, 1.5 kcal/ml with 6 g/%.

The following markers were used for assessing the effectiveness of EEN: total serum proteins, serum albumin, serum globulin, absolute number of lymphocytes, immunoglobulin IgA, IgM, IgG, serum iron, and total iron binding capacity (TIBC). The markers were measured by blood samples from the patients on the first day after admission, on day 8, and on day 15.

Data were collected on a specially designed assessment chart. Details recorded included age, sex, personal information, history information, and dates of assessment. For the measurement of the energy requirements and the patients’ follow-up, there was close collaboration between researchers, physicians, dieticians, nurses, and patients. Evaluation of the results was performed by statistical analysis, using the statistical package SPSS. The statistical methods used were the paired t-test and the chi square (Î2).

Results

Thirty-one patients (mean age, 43.7 yr; SD, 12.2 yr) were studied, of whom 18 (58.1%) were men and 13 (41.9%) women. The characteristics of the 31 patients are presented in Table I. The results show that all proteins increased significantly between measurements. Total proteins showed a significant increase: between days 1 and 8, the mean protein value (± SD) was 5.06 ± 0.90 mg/dl, increasing to 5.76 ± 1.11 mg/dl (p = 0.003); between days 8 and 15, the mean protein value was 5.76 ± 1.11 mg/dl, increasing to 6.33 ± 1.24 mg/dl (p = 0.004), and between days 1 and 15 (p < 0.001) (Fig. 1). Serum albumin also showed a significant increase: between days 1 and 8, the mean value (± SD) was 2.97 ± 0.51 mg/dl, increasing to 3.24 ± 0.64 mg/dl (p="0.015);" between days 8 and 15, the mean value was 3.24 ± 0.64 mg/dl, increasing to 3.40 ± 0.77 mg/dl (p="0.120)," and between days 1 and 15 (p="0.005)" (Fig. 2). Serum globulin likewise increased significantly between days 1 and 8: the mean value (± SD) was 2.06 ± 0.77 mg/dl, increasing to 2.47 ± 0.69 mg/dl (p="0.005);" between days 8 and 15, the mean value was 2.47 ± 0.69 mg/dl, increasing to 2.91 ± 063 mg/dl (p="0.007)," and between days 1 and 15 (p < 0.001) (Fig. 3). The iron level did not change significantly between days 1 and 8 (p="0.09)" or between days 8 and 15 (p="0.280)" but increased significantly between days 1 and 15 (p < 0.008). TIBC increased significantly between days 1 and 15 (p < 0.001). There were no significant changes in the absolute number of lymphocytes. The mean immunoglobulin IgG value increased in all measurements. The mean immunoglobulin IgA value decreased slightly in all measurements. The mean immunoglobulin IgM value increased between the first and second measurements but then decreased between the second and third measurements. The mean value and SD of the numbers of lymphocytes, IgG, IgA, IgM, iron, and TIBC are presented in Table II. Complications related to EEN were diarrhoea in 6.8% of our patients, hyperglycaemia in 19.4%, and electrolyte disturbances in 45.2%.

Markers Measurements Mean value SD Absolute number of lymphocytes (percentage) Day 1 1731,3 952 Day 8 1426,8 677,5 Day 15 1526,1 577,3 IgG (mg/dl) Day 1 922 346,6 Day 8 995,7 313,8 Day 15 997,1 308,8 IgA (mg/dl) Day 1 223,82 125,1 Day 8 211,3 83,4 Day 15 197,8 79,75 IgM (mg/dl) Day 1 91,9 61,85 Day 8 99,03 66,6 Day 15 96,9 64,3 Fe (mg/l) Day 1 34,56 19,87 Day 8 39,25 27,65 Day 15 48,44 19,66 TIBC (mg/l ) Day 1 84,8 42,5 Day 8 97,8 48,6 Day 15 120,6 39,14 Table II- Mean values and SD of measurement in the 31 patients

Discussion

Burn trauma represents one of the most severe and complication-related types of injury the body can sustain. The clinical hypermetabolic response to burn injury, first described by Cope et al.15 in 1953, remains a critical problem in patients with major burn injury. Changes in the post-burn catecholamine metabolism resemble a secondary general response to stress. Depending on the intensity of the trauma, hypermetabolic and hypercatabolic states can persist for several weeks and even months.16,17 The hypermetabolic response is accompanied by severe catabolism and a loss of lean body mass and also by a progressive decline of host defences that impairs the immunological response and leads to sepsis.4,8 At this point, nutritional therapy plays a key role in the overall management of the burn patient.18,20,21 Aggressive nutritional support to meet the increased energy expenditure has been considered essential for the survival of burn patients. EEN has been demonstrated to minimize the catabolic loss, enhance the immunological response,5,8 prevent stress ulcer,9,14,22 and prolong survival. The presence of food in the gut has been shown to stimulate mucosal proliferation, probably as a result of both humoral and nutritional mechanisms.23,24 Improved mucosal integrity has also been demonstrated in burn patients receiving EEN. These findings suggest that EEN may help to diminish the incidence and severity of bacteria translocation by improving or preventing breaches in the mucosal barrier.

With regard to the immunological status of burn patients, it has been shown that total IgG-, IgA-, and IgM-secreting cells and B-cell numbers decrease in burn injuries. The cellular and humoral immune systems have both been reported to be affected in thermal injuries leading to immunosuppression and sepsis.25 The results of our study showed that the administration of EEN in burn patients can enhance their immunological response, leading to increased values of immunoglobulins IgG and IgM. Although the absolute number of lymphocytes did not increase between measurements, the fact that there was no marked decline in the number of circulating lymphocytes indicated that EEN played a significant role in the improvement of the immunological response of the burn patients.

There is now evidence that the alteration of the immunological status in burn patients is strongly related to the trace element (TE) deficit seen in these patients. TE, especially Ca, Se, and Zn, play a key role in many metabolic and immune pathways and are involved in both humoral and cellular immunity. Their deficiency may lead to decreased antibody production, reduced T-cell counts, decreased neutrophil function, and decreased natural killer cell activity. Burn patients suffer acute TE deficiencies owing to extensive cutaneous losses and malnutrition that are likely to induce some of the immune changes observed after burns.26 EEN offers TE supplementation and is associated with increased leukocyte counts, improved immune defence, shorter hospital stay, and decreased mortality.

Recent studies have indicated that increased amounts of micronutrients given to burned patients in the early period following injury reduce the incidence of infections.27 Further reports have suggested that early enteral feeding has been a helpful aid to recovery - complications were rare and prolonged enteral feedings were occasionally required in seriously burned individuals.28,29 Other studies highlight the effectiveness of enteral nutrition as regards wound healing improvement,30 energy expenditure related to burn injury,31 better outcomes of staphylococcal septicaemia, and care for nutrition.32 Burns, sepsis, and injury or surgery all reduce serum glutamine levels. It has been suggested that the lower plasma glutamine concentration contributes, at least in part, to immunosuppression.33 Researchers have tried to find ways to improve protein metabolism through animal (rat) studies (omega-6 and omega-3 fat emulsion on nitrogen retention).34 In addition, it has been shown that enteral diet supplements with arginine in burned rats decrease the mRNA expression of inflammatory cytokines in organs and improves the survival rate.35 In agreement with these results, our study showed a significant increase of all protein mean values. Sixty-two per cent of total body proteins consist of serum albumin, the rest being globulin and fibrinogen. When hyperproteinaemia is present, this is usually a significant increase in serum globulins, without necessarily a similar change in serum albumin.36 Our results showed that total proteins, as also serum albumin, presented a significant increase between measurements, confirming the effectiveness of EEN in the improvement of the patient’s nutritional state.

Serum iron levels present many fluctuations during the day, depending on a variety of factors that affect iron distribution in plasma and storage organs. TIBC values are also affected by iron fluctuations and should be studied together with serum iron levels. Low serum iron concentration is related to sepsis in burn patients. Belmonte et al.37 studied iron metabolism in burned children and concluded that hyposideraemia is a frequent finding in the acute phase of the burn injury, accompanied by increased ferritin levels and decreased transferrin concentrations. Belmonte suggested that low iron values tend to recover without the use of iron supplementation because of an endogenous block release in the acute phase; he thus indicated that iron therapy should not be recommended in the initial period of stress in burn patients. However, the results of our study showed that iron values slightly increased between days 1 and 8, as also between days 8 and 15; however, the significant increase was between days 1 and 15.

In our study TIBC increased significantly between days 8 and 15, as also between days 1 and 15. These results indicated the effectiveness of early enteral nutrition in the burn patient.

Conclusion

Our results demonstrate that early enteral nutrition provided optimal preservation of the nutritional state of burn patients, maintaining nutritional markers within the normal range, and enhanced their immunological the response.

RESUME Les Auteurs de cette étude ont évalué l’efficacité de la nutrition entérale précoce (NEP) des patients brûlés, en association avec l’état nutritionnel et la réponse immunologique. Les patients atteints de brûlures en plus de 25% de la surface corporelle totale hospitalisés dans le Département de Chirurgie Plastique et de l’Unité des Brûlures de l’Hôpital d’Etat d’Athènes pendant une période de trois ans ont été inclus dans l’étude. Le protocole de support suivi par les Auteurs incluait la NEP dans les premières six heures, moyennant un tube nasogastrique et l’administration de formules ayant une valeur nutritionelle qui variait selon les nécessités et la tolérance des patients. Les Auteurs ont administré: 1. valeur basse de kcal, 0,5 kcal/ml avec 2 g/%; 2. valeur normale, 1 kcal/ml avec 4 g/%; 3. valeur élevée de kcal/ml avec 6 g/%. Les marqueurs suivants ont été utilisés pour évaluer l’efficacité de la NEP: les protéines totales séreuses, l’albumine séreuse, la globuline séreuse, le numéro absolu des lymphocytes, l’immunoglobuline IgA, IgM et IgG, le fer séreux, et la capacité totale de fixation du fer (CTFF). Des prélèvements de sang ont été effectués dans chaque patient le premier jour après l’hospitalisation, le huitième jour et le quinzième. Les résultats ont été réunis dans une carte d’évaluation. Les résultats ont été enfin évalués pour l’analyse statistique. Trente et un patients (âge, 17-95 ans, âge moyen, 43.7 ± 12.2 ans) et pourcentage brûlé 25-85% (pourcentage moyen, 43.4 ± 18.67%) ont été étudiés. Toutes les valeurs protéiques moyennes augmentaient en manière significative entre la première et la troisième évaluation: les protéines totales augmentaient de 5,06 à 6,33 mg/dl (p < 0.001); l’albumine séreuse de 2,97 à 3,40 mg/dl (p < 0.005); la globuline séreuse de 2,06 à 2,91 mg/dl (p < 0.001). Le fer augmentait de 34,56 à 48,44 mg/l (p < 0.008) et le TIBC de 84,80 à 120,60 mg/l (p < 0.001. Les Auteurs n’ont pas observé aucun changement significatif dans le numéro absolu des lymphocytes ni dans l’immunoglobuline IgA, IgM et IgG. Les résultats ont démontré que la nutrition entérale précoce fournissait une conservation optimale de l’état nutritionnel des patients et maintenait les marqueurs nutritionnels aux valeurs normales.

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