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Original Research Communications |
1 From the Unité de Nutrition, Service de Gastroentérologie et Nutrition, Service de Biochemistry, Service de Nuclear Medicine, and Service de Nutrition Physiology, Hôpital Bichat-Claude Bernard, Paris.
2 Address reprint requests to D Rigaud, Unité de Nutrition, Hôpital Bichat-Claude Bernard 46, rue Henri Huchard, 75877 Paris Cedex 18, France.
| ABSTRACT |
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Objective: The objective was to compare the resting energy expenditure (REE) of 5 extremely malnourished dying patients [body mass index (in kg/m2): 9.77 ± 0.1] with that of 16 less-malnourished anorexia nervosa (AN) patients.
Design: REE was measured by indirect calorimetry and body composition was measured by anthropometry and dual-frequency bioelectrical impedance analysis. Fasting serum insulin, thyroid hormone, and catecholamine concentrations were also determined.
Results: At the start of refeeding, REE was high in each of the 5 extremely malnourished dying patients, whereas it was low in the 16 AN patients (
± SD: 5174 ± 391 kJ/d compared with 3844 ± 619 kJ/d; P < 0.05). The high REE value in the 5 extremely malnourished dying patients was associated with almost no fat mass (FM), high urinary nitrogen loss (16.4 ± 2.9 g/d), low serum fatty acid concentrations (0.36 ± 0.23 mmol/L), and low or normal serum insulin, thyroid hormone, and catecholamine concentrations. During the first 24 wk of refeeding, REE and nitrogen loss decreased, whereas fatty acid concentrations increased in each of the 4 surviving patients; REE and urinary nitrogen output increased in the 16 AN patients.
Conclusion: In malnourished persons near death, there is an increase in REE and in protein catabolism. The reason for this increase is unknown but could relate to consumption of the last mobilizable muscle mass and to diseased cellular membranes.
Key Words: Resting energy expenditure malnutrition oxygen consumption anorexia nervosa women
| INTRODUCTION |
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The metabolic expression of extreme malnourishment in persons near death is unknown. Le Maho's research team described, in the king penguin Aptenodytes patagonicus (8) and in rats (9, 10), successive phases of energy expenditure and protein breakdown during prolonged starvation. During the initial phase, which lasted several days, a decrease in protein utilization was observed. The second phase, lasting several weeks, was characterized by an important sparing of visceral and muscle proteins. During the terminal phase (ie, the last few days before death), an important increase in protein oxidation and breakdown was again observed.
No such data are available for humans. In a 15-y study of refeeding extremely malnourished dying patients, only a few patients with a body mass index (BMI; in kg/m2) <10 have been seen at our unit. The paradoxical REE, body composition, and metabolic and hormonal data of 5 extremely malnourished women near death and of 16 malnourished female anorexia nervosa (AN) patients were measured and compared.
| SUBJECTS AND METHODS |
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The AN patients and healthy subjects served as control subjects (Table 1
). The control subjects were recruited by advertisement at Bichat University, Paris. The AN patients had BMIs between 12 and 16 and the healthy subjects had BMIs between 19 and 25. The AN patients and healthy subjects were matched for age (±2 y) with the 5 dying patients. The research protocol was explained to the subjects, who gave informed, written consent. The study protocol was in accordance with the guidelines of the Bichat Hospital Ethical Committee.
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150 g/d during the first 2 wk of refeeding. The 16 AN patients were refed orally as well as by CEN and had a weight gain of 150200 g/d. Each patient consumed a low-sodium diet. The procedure used to measure REE was described in detail previously (12). Briefly, the subjects fasted overnight (tube and oral feeding was interrupted at 2200 the night before) and then were placed in a quiet, ventilated room (22.7 ± 0.5°C). After 30 min of bed rest, including 15 min under a ventilated hood, to stabilize gas exchanges, REE was recorded for 20 min between 0830 and 1000. The subjects remained in a supine position throughout the procedure, holding the hood in which air flow was monitored according to the respiratory rate.
Oxygen consumption and carbon dioxide production
Oxygen consumption (
O2) and carbon dioxide production (
CO2) were measured online by using open-circuit indirect calorimetry with a ventilated-hood system (12), which consisted of 2 paramagnetic analyzers for oxygen, 2 infrared analyzers for carbon dioxide, and a mass flow meter to determine precise airflow rates.
O2 and
CO2 were calculated as being the difference between expired gases and room gases. Corrections for nonprotein respiratory quotient and REE were made by subtracting the
O2 from the
CO2 for protein oxidation from urinary nitrogen output. The reproducibility was >96%. REE was calculated according to the method of Ben Porat et al (13).
Body weight and body composition
Body weight was measured every 2 d while the subjects were fasting. Body composition was assessed each week by measuring skinfold thicknesses at the biceps, triceps, suprailiac, and subscapular sites (14) and every 2 wk by conducting 2-frequency (5 kHz and 1 MHz) bioelectrical impedance analyses (BIA) (15) with a portable 2-electrode analyzer (IMP BO 1; l'Impulsion, Caen, France). In addition, muscle circumferences of the brachia and thigh (at the middle of the limb segment) and of the calf at the largest site (16, 17) were measured every 2 wk; the skinfold thickness at each site was subtracted. Muscle mass was estimated every 2 wk on the basis of the mean of 3 consecutive 24-h urinary creatinine outputs by using an analytic procedure based on the Jaffé procedure (18).
Other measurements
Energy intake was estimated daily by one dietitian from a 7-d food record and on the basis of the volume remaining in the enteral feeding bottles (7). Urinary nitrogen was calculated weekly by chemiluminescence (17) on the basis of the mean of 3 consecutive 24-h measures. Serum fatty acid concentrations were determined by gas chromatography with use of a CP-SIL 8 CB (0.12 µm) column (19). Serum albumin and transthyretin were measured by laser nephelometry (20). Serum sodium, potassium, calcium, phosphorus, zinc, and magnesium and red blood cell magnesium concentrations were measured by using a Technicon SMA 6 (Technicon, Paris). Every 2 wk, serum thyroid hormone (free triiodothyronine and thyroxine) and thyrotropin concentrations were measured by use of radioimmunoassay and serum catecholamines (epinephrine, norepinephrine, and dopamine) were measured by use of HPLC and electrochemical detection (21).
Statistical analyses
The effect of refeeding was tested by comparing the values obtained before with those obtained after refeeding with use of the nonparametric Mann-Whitney U test and analysis of variance (ANOVA). These tests were also used to compare values between the 3 groups. Statistical differences were weighted with the Bonferroni adjustment. Results were considered to be significant if P values were <0.05. All analyses were made with SYSTAT for WINDOWS 95 (1996; Systat Inc, Chicago). Results are reported as means ± SDs.
| RESULTS |
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Resting energy expenditure
At the start of refeeding, REE was high in each of the 5 dying patients: 5174 ± 391 kJ (1194 ± 170 kcal)/d (Figure 1
). Each REE value was significantly higher than the highest value found in the 16 AN patients. During the first 4 wk of refeeding, REE decreased in each of the 4 dying patients who were still alive. These data contrasted with data for the AN patients: the initially low REE values increased after 1 wk of refeeding in 14 of the 16 patients (P < 0.01) and remained unchanged in the 2 other patients. The same result was obtained when REE values were corrected for FFM. At the start of refeeding, REE/FFM was significantly higher in the 5 dying patients [210 ± 32 kJ (50.3 ± 7.6 kcal)kg FFM-1d-1] than in the AN patients [114 ± 8 kJ (27.4 ± 1.8 kcal)kg FFM-1d-1]. REE then decreased to 160 ± 38 kJ (38.4 ± 9.2 kcal)kg FFM-1d-1 at week 4 of refeeding in the dying patients, but increased to 151 ± 31.3 kJ (36.2 ± 7.5 kcal)kg FFM-1d-1 in the AN patients (P < 0.01).
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Body weight and body composition
Brachial, calf, and thigh muscle circumferences in the dying patients were 42%, 48%, and 39% lower and mean urinary creatinine output was 42 ± 9% lower than values in the healthy subjects (Table 1
). FFM represented
100% of body weight in the dying patients compared with 8892% in the AN patients. Total body water was overestimated by BIA in the 4 dying patients: FFM exceeded body weight in 2 patients and represented >90% of body weight in the other 2 patients. By week 8, body composition improved: body weight increased from 24.55 ± 1.64 to 32.67 ± 1.73 kg, FFM increased from 24.6 ± 2.1 to 29.4 ± 3.7 kg, and FM increased from 0.05 ± 1.1 to 3.4 ± 1.8 kg; brachial, calf, and thigh muscle circumferences improved but remained 37%, 35%, and 42% lower (P < 0.01), respectively, than normal. Mean urinary creatinine output by week 8 was 601 ± 69 mg/d, 34% below values in the healthy subjects.
Energy intake
The mean 7-d energy intake in the dying patients before hospital admission was near zero: 962 ± 239 kJ/d (230 ± 57 kcal/d). This value was lower than that of the 16 AN patients: 3511 ± 656 kJ/d (840 ± 157 kcal/d). Food intake increased in the 4 dying patients: 4012 ± 787, 6258 ± 1247, 8642 ± 1186, 10308 ± 947, and 11251 ± 1471 kJ/d, respectively, after 1, 2, 3, 4, and 8 wk of refeeding. It also increased, by 100 %, in the AN patients.
Urinary nitrogen loss
Urinary nitrogen output was initially high (16.4 ± 2.9 g/d) in the dying patients and decreased during refeeding (Figure 2
). This contrasted with the low initial value and with its increase after enteral feeding in the 16 AN patients.
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Other results
No inflammatory process was found in our patients, there was no bacteria in the urine or blood, thoracic X-ray results were normal, and serum acute phase reactive protein concentrations were low. In addition, none of the patients was taking any medication known to increase REE (namely thyroid hormones).
| DISCUSSION |
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The fact that only one of our extremely malnourished dying patients died during the study was surprising. On the basis of personal results and 11 reports from the literature, Henry (22) concluded in 1990 that survival is not possible in humans with a BMI < 10 (22). The very low body weight in our patients was attributable almost exclusively to FFM, of which a large portion was excess water, as suggested by edema of the legs, low plasma sodium concentrations, and high concentrations of total, intracellular, and extracellular water (by BIA). However, our measurements of body water were erroneous; we found total body water to be >90% of body weight in 4 patients, which is impossible. One of the reasons total body water was overestimated was that FFM was calculated from the water and electrolyte contents of normal cells. Another possible reason is that the pumps and channels of the cells were damaged, inducing changes in membrane resistance.
The paradoxical increase in REE in the dying patients was not explained by confounding factors; none of the subjects had any infectious or inflammatory disease. The dying patients were confined to bed and were not able to do any physical activity. The low amount of glucose or CEN received by the patients 1 or 2 d before REE was measured (<2090 kJ, or 500 kcal/d) also did not explain the increase in REE because this is the first time in our >15 y of conducting refeeding studies that we noted such an increase.
This initial increase in REE in the dying patients was associated with a high urinary nitrogen output, which suggests high protein oxidation. This condition was surprising because malnourished patients have a very low nitrogen intake and thus a low nitrogen oxidation and output (23). As suggested by a mean fasting respiratory quotient in the range of protein oxidation (0.84), low fatty acid and glucose concentrations, and a near-zero FM, there was not enough fat or glycogen available for oxidation in these patients. Thus, massive oxidation of FFM proteins became mandatory; FFM catabolism produces 1 kcal/g (0.25 g protein/g FFM). In the present study, a mean of 16.4 g urinary nitrogen output/d was noted, suggesting a breakdown of 410 g FFM, which provides
410 kcal, ie, 34% of the REE. The remaining energy from REE may have been provided by blood lipids or by the last fat stores. It is also possible that the respiratory quotient and the REE were affected by energy input (even minimal) the day before. During refeeding, REE decreased, as did nitrogen losses, which may have been related to the sparing effect of nonprotein energy input on protein catabolism (24).
The initial increase in REE may also have been related to an increase in the permeability of the mitochondrial membrane. In healthy subjects the permeability of the mitochondrial membrane is relatively low; in the dying patients in the present study, the permeability to the protons may have increased. Such an increase would enhance leakage through the membrane and subsequently decrease the oxidative phosphorylation efficacy (25, 26) and increase oxygen consumption. A deep deficiency in essential fatty acids was also associated in vitro with an increase in mitochondrial membrane permeability (26). Such a deficiency, which is likely during severe starvation, was shown in rats to be responsible for an increase in cell respiration, a depletion of energy stores, and an increase in REE (27). The increased REE in such patients may also have been due to diseased cellular membranes throughout the body, a condition that induces dysfunction of all cellular components. Indeed, much of the oxygen needed was used to generate ATP to maintain cellular membrane potentials and to pump and channel energy requirements.
An increase in thyroid hormone or catecholamine secretion might be another explanation for an elevated REE (28, 29). In our dying patients, however, no such increase was noted. A role for thyroid hormones could not be excluded because free triiodothyronine concentrations were within reference ranges in these patients but were low in 91% of the 280 malnourished AN patients admitted to our Unit over 10 y. Serum catecholamine concentrations did not increase in the dying patients after refeeding.
In conclusion, in the dying patients there was a paradoxical increase in REE above values usually observed in other states of food deprivation. This phenomenon appears to be similar to what has been observed in the king penguin Aptenodytes patagonicus (8). This king penguin syndrome is partly attributable to oxidation of the last available energy, ie, the FFM protein stores. The survival of such patients is possible if refeeding is initiated as soon as possible: intravenous water, potassium, phosphorus, vitamins, low saline, and low glucose input (75100 g/d) on the first day and CEN (providing an energy input of 0.5 x REE and a low protein input of 0.75 gkg-1d-1) on the second day. On the third day, the energy input should be increased to equal the REE and the protein input should increase to 1.5 gkg-1d-1. Over the subsequent 2 wk, energy input should be maintained at 1.5 x REE (providing
1500 kcal/d).
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