The influence of calorie source on water and sodium balances during intravenous refeeding of malnourished rabbits

The influence of calorie source on water and sodium balances during intravenous refeeding of malnourished rabbits

Chid Nulrilion (lYY2)11:5%61 @ Longman GroupUK Ltd 1992 The influence of calorie source on water and sodium balances during intravenous refeeding of ...

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Chid Nulrilion (lYY2)11:5%61 @ Longman GroupUK Ltd 1992

The influence of calorie source on water and sodium balances during intravenous refeeding of malnourished rabbits G. FRANCH, X. GUIRAO,

M. GARCIA-DOMINGO,

Department of Surgery and Surgical Autenoma de Barcelona, P. Maritim, Department of Surgery)

M. J. GIL, E. SALAS and A. SITGES-SERRA

Research Unit, Hospital Universitari del Mar, Universitat 25-29, 08003 Barcelona, Spain (Correspondence to A.S.-S.,

ABSTRACT-34 New Zealand rabbits were starved until a mean weight loss of 15% to 20% was achieved and then were parenterally re-fed with four different total parenteral nutrition (TPN) formulae for 6 days. Regimens were isocaloric (85 kcaI/kg/day) and isonitrogenous (0.52gN/kg/ day) with the following formulae: group S-GLU-70 (water lOOmI/kg/day, Na 7mEq/day and 70/30% of calories as glucose/lipids, n = 9), group S-GLU-50 (water lOOml/kg/day, Na 7mEq/day and 50/50% of calories as glucose/lipids, n = 9), group L-GLU-30 (water 70ml/kg/ day, no sodium and 30/70% of calories as glucose/lipids, n = 8) and group L-GLU-50 (water 70ml/kg/day, no sodium and 50150% of calories as glucose/lipids, n = 8). The group S-GLU-70 showed the highest water and sodium balances (p = 0.001 respectively, ANOVA test). Group S-GLU-70 showed also a greater weight gain (p = 0.0001) and, although not statistically significant, the lowest albumin at the end of the TPN. Glucose load appears to be responsible for the rapid weight gain and positive water and sodium balances during TPN in depleted non-stressed animals.

Introduction

We report the result of a prospective randomised experimental study comparing the response to four different TPN formulae in starved rabbits. The .aim of the study was to investigate the influence of the water, sodium and glucose content of the diet on weight gain, water and sodium balances and changes in the serum albumin concentrations.

Chronic malnutrition increases post-operative morbidity and mortality. Mullen et al (1) showed that, in depleted patients (with a Prognostic Nutritional Index equal or greater than 50%), postoperative morbidity and mortality could be reduced by a short (7-10 days) pre-operative course of parenteral feeding. Starker et al (2) reported two patterns of response to pre-operative parenteral nutrition in malnourished non-stressed individuals. About half of them showed a decrease in body weight with increasing albumin values, reflecting negative water and sodium balances, and did fairly well after surgery. In contrast, the remaining patients failed to exhibit this diuretic response, further expanded their extracellular fluid and developed post-operative complications. The authors did not mention the water and sodium content of the parenteral nutrition formulae and the non-protein calorie source used and it is our view that these could have influenced the response to re-feeding. In his classical studies on starvation physiology, Gamble (3) observed the water and sodium retention effect of diets with high glucose content.

Materials and methods 34 New Zealand rabbits were starved until a mean weight loss of 15%-20% was achieved and then submitted to total parenteral nutrition. The rabbits were randomly allocated to receive one of four different TPN formulae. Regimes were isocaloric (85 kcal/kg/day) and isonitrogenous (OS2gN/kg/day) (4). The content of water and sodium and the non-protein calorie source differed within the groups (Table 1). The ANOVA test was used for quantitative data to assess differences between groups. Two tailed Student t test for unpaired data was used to assess differences when comparing only two groups. The level of statistical significance was considered to be 59

60 INFLUENCEOFCALORIESOURCEONWATERANDSODIUMBALANCES 70% GLUCOSE Group STANDARD WATER-Na

<

SO%GLUCOSE Group

S-GLU50. Although not statistically significant, in group S-GLU-70 serum albumin decreased twice as much as in the S-GLU-50 group.

600

Discussion

700 600 500 4w 300 200 loo 0 WATER

balance

(ml)

SODIUM balance (mEq)

WEIGHT gain (%)

Fig. Differences

in weight gain and water and sodium balances between S-GLU-70 and S-GLUJO

less than 5% (p < 0.05). All numerical values are expressed as mean f standard deviation. Results After 6 days on TPN, S-GLU-70 showed the highest water and sodium balances (p = 0.0001 and p = 0.001 respectively) (Table 2). Group S-GLU-70 showed a greater weight gain (p = 0.0001). Although not statistically significant, serum albumin changes showed a higher decrease in their values in group S-GLU-70. The three groups receiving either 50% or 30% of nonprotein calories as glucose did not show significative differences in the above mentioned parameters. When groups S-GLU-70 and S-GLUJO were compared (Fig.) group S-GLU-70 showed a higher water and sodium balance (737 f 192ml vs. 490 + 166m1, p = 0.01; 22.2 + 8mEqvs. 3.5 + 13mEq. p = 0.002, respectively) and greater weight gain (10.5 + 4% vs. 0.5 f 4%, p = 0.0001) than

Body composition in chronic protein calorie depletion is characterised by loss of fat and muscle tissue and a relative increase in the extracellular fluid and total body sodium (5). There is little information on the response to parenteral feeding in this situation. From studies carried out in under-developed countries it is known that kidneys of malnourished children and adults do not handle sodium loads adequately (6). However, there is very little information concerning this issue in hospitalised malnourished patients. There is also little information on the most appropriate intravenous calorie source for re-feeding severely under-nourished surgical patients in relation to possible acute alterations in their body composition. MacFie et al (7) demonstrated that glucosebased regimes result in more water retention and fat gain than those including fat as a source of 60% of the non-protein calories. The latter regimes also did better in terms of protein metabolism. In the present study we have investigated the response to intravenous re-feeding in an experimental model of simple non-stressed starvation in rabbits. The results show that TPN composition may be an important factor influencing the component of this response linked to water and sodium metabolism. As already pointed out by other authors (8,9), changes in extracellular water compartment appear to play a major role in determining weight and serum albumin concentration shifts during short-term TPN in severe chronic malnutrition. In our initial experience in humans (lo), a group of patients fed with standard amounts of water and

Table 1 TPN formulae

Formula Calories (kcaUkg/day) Nitrogen &N/kg/day) kcaUgN Glucose/fat (%kcal) Water (ml/kg/day) Sodium (mEq/day) Potassium (mEq/day)

Standard water-sodium s-GLU-70 S-GLU50 85 0.527 161 70130 100 7 7

85 0.527 161 50/50 100 7 7

Low water-sodium

L-GLU-30 85 0.527 161 30/70 70 0 7

L-GLUJO 85 0.527 161 50/50 70 0 7

CLINICAL NUTRITION

61

Table 2 Changes and balances after re-feeding

Parameters

Standard water-sodium S-GLU-70 S-GLUJO (n = 9) (n = 9)

Low water sodium L-GLU30 L-GLUJO (n = 8) (n = 8)

TPN volume (ml) Diuresis (ml) Water balance (ml) Sodium balance (mEq) Weight gain (%) Albumin changes (%)

1519 781 737 22.2 10.5 -16

1071 (143) 601 (192) 416 (129) -10 (8.6) 2.6 (5.2) 4.6 (11)

(234) (128) (192) (8) (4) (18)

1573 (156) 1084 (194) 490 (166) 3.5 (13) 0.5 (4) -8 (16)

1012 (58) 623 (115) 388 (99) - 10 (3) 0.4 (3.4) -7 (14)

P 0.001 0.0001 0.0081 0.001 O.O@Ol 0.09

Figures are expressed as mean (sd)

sodium did gain more weight than those undergoing glucose, water and sodium restriction. Serum albumin decreased in proportion to the magnitude of the sodium balance. In the present study, the response to TPN differed in the two groups of animals receiving standard amounts of water and sodium but different glucose loads. Total diuresis was lower in group S-GLU-70 (781 f 128ml vs. 1084 + 194m1, p=O.OOl),thi s 1ea d ing to higher water and sodium balances (737 + 192ml vs. 490 + 166m1, p = 0.01; 22.2 f 8mEq vs. 3.5 + 13mEq, p = 0.002) and therefore resulting in a greater weight gain (10.5 + 4% vs. 0.5 + 4%) p = 0.0001). According to the results of the present study, it appears that high intravenous glucose loads play an important role in inducing weight gain through positive sodium and water balances. Further studies of water and sodium metabolism, catecholamines and extracellular water measurements are warranted to improve understanding of the mechanisms leading to water and sodium retention during high carbohydrate parenteral feeding.

Acknowledgements Thanks are due to Drs. F. Echevarne and B. Fernandez from the Echevarne Laboratory for performing all the biochemical tests. This investigation has been supported by a grant from the Ajinomoto Company, and a grant from the

‘Fond0 de Investigaciones Sanitarias de la Seguridad Social no. 9OlO214.

References 1. Buzby G P, Mullen J L, Matthews D C, Hobbs C L, Rosato E F 1980 Prognostic nutritional index in gastrointestinal surgery. American Journal of Surgery 139: 160-7 2. Starker P M, Lasala P A, Askanazi J, Gump F E, Forse R, Kinney J 1983 The response to TPN. A form of nutritonal assessment. Annals of Surgery 198: 720-724 3. Gamble J L 1946-1947 Physiological information gained from studies on life raft ration. Harvey lectures 42: 247-273 4. Committee of Animal Nutrition 1977 Nutrient requirements of rabbits. National Academy of Sciences, Washington D.C. 5. Elwyn D H, Bryan-Brown C W, Shoemaker W C 1975 Nutritional aspects of body water dislocation in postoperative and depleted patients. Annals of Surgery 182: 7685 6. Klahr S, Alleyne G A 0 1973 Effects of chronic proteincalorie malnutrition on the kidney. Kidney International 3: 129-141 7. MacFie J, Smith R C, Hill G H 1981 Glucose or fat as a nonprotein energy source? A controlled trial in gastroenterological patients requiring intravenous nutrition. Gastroenterology 80: 103-107 8. Starker P M, Gump F E, Askanazi J et al 1982 Serum albumin levels as an index of nutrition support, Surgery 91: 194-199 9. Forse R A, Shizgal H M 1980 The assessment of malnutrition. Surgery 88: 17-24 10. Sitges-Serra A, Gil M J, Martinez-R6denas F 1988 The influence of TPN formulation on the metabolic response to preoperative refeeding in depleted patients. British Journal Clinical Practice 42 (Suppl. 63): 133-137.