Controlled trial of the metabolic effects of a very-low-calorie diet: short- and long-term effects

Resting energy expenditure (REE), weight, and body composition were measured up to seven times in 13 obese women during a 24-wk study. Patients were randomly assigned to a very-low-calorie diet (VLCD, 500 kcal/d) or a balanced-deficit diet (BDD, 1200 kcal/d). After 8 wk of supplemented fasting, REE of the VLCD patients decreased by 17% whereas that of the BDD patients was virtually unchanged. REE of the VLCD patients increased during 12 subsequent weeks of realimentation such that differences in REE between the two groups were not statistically significant at week 24 (VLCD = -11%, BDD = -2%). Reductions in weight and fat-free mass (FFM) were 12.1% and 3.6% for the VLCD patients and 10.6% and 4.1% for the BDD patients, respectively. There were no significant differences between the groups in pre- to posttreatment changes in REE normalized to FFM. Results suggest that REE recovers partially after consumption of a VLCD. They also provide evidence of a possible metabolic advantage of weight loss by a more moderate restriction.

Increased contribution of protein oxidation to energy expenditure in head-injured patients

Six patients with acute head injury (initial GCS 4.8 +/- 1.7) were studied to determine the contribution of protein oxidation to resting energy expenditure (REE). Patients were studied on the second or third day post-injury and prior to implementation of nutritional support. Variables measured included REE by indirect calorimetry (normalized to percent predicted energy expenditure calculated from the Harris-Benedict equation). 24-hr urinary nitrogen excretion, calorie, and nitrogen intake. All patients received dexamethasone (39 +/- 2 mg/day) and three received pentobarbital. Mean REE was widely variable, ranging from 43 to 128% of predicted (mean, 90 +/- 31%). Mean 24-hr urinary nitrogen excretion was 16.5 +/- 5.8 g. The contribution of protein oxidation to REE was 30 +/- 4%. The contribution of protein oxidation to REE did not parallel REE (r = -0.237, p = NS) or REE expressed as percent predicted (r = -0.258, p = NS). The contribution of protein oxidation to energy expenditure is greater in acute heat trauma than previously described soft tissue injury and sepsis. The observed excessive nitrogen catabolism and increased contribution of protein oxidation to resting energy expenditure suggest accentuated protein requirements in respect to energy needs in head-injured patients.

Effect of propranolol on nitrogen and energy metabolism in sepsis

Pharmacologic therapy designed to block adrenergic activity or alter hormonal milieu may modulate energy and protein metabolism in stress. The metabolic effects of propranolol (beta adrenergic receptor blocker) in sepsis was investigated in 22 well-nourished rats that underwent superior vena caval cannulation, cecal ligation, and puncture. Animals were randomly assigned to receive either a continuous infusion of 0.7 mg/day of propranolol combined with parenteral nutrition (n = 11) or parenteral nutrition alone (n = 11). Both groups received isocaloric, isonitrogenous, isovolemic, parenteral nutrition post-operatively for 24 hr. Nitrogen balance was better for the propranolol group than for the control group (+743 +/- 84 mg/kg/day versus +300 +/- 63 mg/kg/day, respectively, P less than 0.05). A significant difference between the pharmacologic therapy and control groups was noted for urinary 3-methylhistidine excretion versus control (0.99 +/- 0.08 micrograms/kg/day versus 7.5 +/- 0.37 micrograms/kg/day, respectively, P less than 0.01). Measured energy expenditure was similar for both pharmacologic therapy and control groups (149 +/- 20 kcal/kg/day versus 134 +/- 11 kcal/kg/day, respectively, P = N.S.). No statistically significant difference was demonstrated for 24-hr survival between propranolol and control groups (73 and 64%, respectively). Continuous, low-dose propranolol promotes nitrogen retention and decreases 3-methylhistidine excretion without altering energy expenditure in parenterally fed septic rats.

Barbiturate therapy reduces nitrogen excretion in acute head injury

The effect of pentobarbital on nitrogen and energy metabolism was evaluated in seven severely head-injured patients (Glasgow Coma Scale 4.7 +/- 1.7) within the first week postinjury. Measured energy expenditure (% of predicted) was significantly lower in the pentobarbital group (n = 4) versus control (n = 3) (76 +/- 23% versus 132 +/- 28%, respectively, p less than 0.01). Similarly, 24-hour urinary nitrogen excretion was lower for the barbiturate group compared to control (11.2 +/- 4.0 gm versus 19.5 +/- 3.3 gm, respectively, p less than 0.01). No statistical difference was noted for urinary 3-methylhistidine excretion between the barbiturate and control groups (43 +/- 12 mcg/day versus 47 +/- 14 mcg/day, respectively, p = N.S.). Barbiturate therapy decreases measured energy expenditure and reduces nitrogen excretion without significantly altering 3-methylhistidine excretion in head-injured patients. The metabolic effects of pentobarbital may enable the ability to achieve energy and nitrogen equilibrium during metabolic support of acutely head-injured patients.

Energy metabolism during transplantation rejection

The effect of transplantation rejection on energy metabolism is unknown. In order to investigate energy expenditure changes in this setting, we used an eight-cage rat indirect calorimeter to measure resting energy expenditure (REE) in the well-defined model of rat cardiac transplantation. Preoperative baseline measurements of REE were performed on Lewis recipients of allogeneic (Wistar Furth) or syngeneic (Lewis) heterotopic abdominal cardiac grafts (80.3 +/- 3.3 kcal0.75/day). Postoperatively, REE was measured on days 1 through 10, 15, and 20. An abnormal REE was defined as a greater than 10% change from the preoperative value. All cardiac allografts were rejected on postoperative day 7, whereas syngeneic hearts contracted for more than 100 days. Both groups of animals had a hypermetabolic response to surgery on postoperative day 1 compared with preoperative values (93.0 +/- 7.6 kcal/kg0.75/day, p less than 0.01). On postoperative day 2, REE normalized to preoperative baseline values in the syngeneic group and remained unchanged for the duration of the study (80.4 +/- 1.0, p = 0.49). In the allogeneic group, on postoperative days 3 through 6 an abnormal REE was recorded in 22 of 28 measurements compared with only 3 of 16 in the syngeneic group (p less than 0.001). After transplant rejection, REE normalized to preoperative values in the allogeneic group. Characteristic changes in energy expenditure occur during transplantation rejection. These changes in REE preceded rejection in this animal model.

Pentobarbital improves nitrogen retention in sepsis

Pentobarbital therapy has been associated with decreased urinary nitrogen excretion and resting energy expenditure in stressed patients. The metabolic effects of pentobarbital in sepsis were investigated in 29 well-nourished rats who underwent superior vena caval cannulation, cecal ligation, and puncture. Animals were randomly assigned to receive either a continuous infusion of 20 mg/kg/day of pentobarbital combined with parenteral nutrition (n = 13) or parenteral nutrition alone (n = 16). Both groups received isocaloric, isonitrogenous parenteral nutrition postoperatively for 24 hr. Mean nitrogen balance (+/- SEM) was better in the pentobarbital group (+169 +/- 76 mg/kg/day vs -190 +/- 66 mg/kg/day, p less than 0.01). No significant differences between the pentobarbital and control groups were noted for urinary 3-methylhistidine excretion (9 +/- 0.7 micrograms/kg/day vs 11 +/- 0.6 micrograms/kg/day, respectively) or 24 hr survival (77% vs 69%, respectively). Pentobarbital improves nitrogen retention without decreasing urinary 3-methylhistidine excretion in septic rats.

Resting energy expenditure, body composition, and excess weight in the obese

This study investigated differences between measured and predicted resting energy expenditure (REE) in 80 women who averaged 104.6 kg in weight and were 49 kg and 88% overweight. Body composition analysis showed that 68% of the excess weight was fat and 32% was fat-free mass (FFM). Normalized for height, total body potassium (TBK) was 113 +/- 15% and total body water (TBW) was 133 +/- 21% of values in nonobese controls. The health of the FFM, defined as the potassium content per kg of FFM, was 84 +/- 13% of normal. Measured and predicted REE were only modestly related (r = +.59), and only 59% of measured REEs were within 10% of predicted values. A stepwise multiple regression indicated that weight was the single best predictor of measured REE and that the size of the FFM made a significantly greater contribution to REE than did the size of the fat mass. Commonly used equations for the prediction of REE are not appropriate for moderately or severely obese patients. Caloric prescription for weight reduction must be tailored to individuals rather than recommending the same caloric intake to persons with varying metabolic rates.

Spontaneous retraction of indwelling catheters: previously unreported complications

The development of totally implantable reservoir central venous access systems has been an important advance in patients requiring long-term central venous access. With lower rates of infection and thrombosis than those with external catheters, they have potential for greater longevity and patient acceptance. Complications such as subcutaneous prosthetic infection, infusate extravasation, and difficulty in locating and puncturing the port have been reported. We present two cases of catheter migration and withdrawal from the subclavian vein. This presumably occurred from the action of the underlying pectoralis muscle on the reservoir, as well as a "jetting effect" during flushing. We make suggestions for prevention of similar problems in the future.

Reduction of methotrexate toxicity with improved nutritional status in tumor-bearing animals

The administration of chemotherapy in clinical situations is limited frequently because of the associated toxicity to normal bone marrow cells, gastrointestinal epithelium, and other host tissues. Although nutritional support has been advocated to reduce chemotherapy-related toxicity in cancer patients, few studies substantiate this clinical impression. The current study was performed to determine the role of nutritional status and enteral nutrient intake as determinants of methotrexate (MTX) toxicity in a well-controlled, tumor-bearing animal model. After subcutaneous mammary tumor (AC-33) inoculation, 56 female Lewis/Wistar rats were assigned randomly to one of the following two nutritional regimens for 14 days: (1) protein-depleted chow (PC) (0.03% protein; 4.27 kcal/g) or (2) standard chow (RC) (22.0% protein; 3.50 kcal/g). After 7 days of dietary control, all animals received one of three weight-adjusted doses of MTX (5, 10, or 20 mg/kg intramuscularly [IM] ) or placebo. All animals received leucovorin rescue (0.6 mg IM) at 6 and 24 hours after MTX injection. Improved nutritional status was associated with a significant reduction in objective measures of MTX-related morbidity and mortality. At low doses of MTX (5 and 10 mg/kg), the mean duration of clinical signs of toxicity (i.e., hair loss, lethargy, and diarrhea) and severity of leukopenia were greater in protein-depleted (PD) animals. With high-dose MTX (20 mg/kg), mortality was increased significantly in PD animals (100%) compared with well-nourished animals (0%). Equivalent tumor response was observed in PD and well-nourished animals. Thus, improved nutritional status by enteral nutrition reduced the morbidity and mortality associated with MTX significantly in this tumor-bearing animal model.

A randomized clinical trial of total parenteral nutrition in malnourished surgical patients: the rationale and impact of previous clinical trials and pilot study on protocol design

The rationale for a large-scale clinical trial of preoperative total parenteral nutrition (TPN) is described in the context of previous clinical trials that have attempted to demonstrate reduction of operative morbidity with preoperative TPN. Defects in study design or execution potentially compromising the validity of these studies are analyzed. Results of a single-institution pilot study performed during the planning phase of the multiinstitutional preoperative TPN trial are presented. This literature review and pilot study provided the data necessary to permit appropriate design of many critical elements in the protocol for the clinical trial including sample size, eligibility criteria, duration and intensity of treatment regimens, and end-point criteria. The rationale underlying critical decisions in protocol design are presented in detail to allow more meaningful interpretation of the results of the clinical trial.

The link between nutritional status and clinical outcome: can nutritional intervention modify it?

Most clinicians subjectively feel that malnutrition in surgical patients is associated with poor clinical outcome. This overview provides a chronologic review of studies relating poor nutritional status to increased surgical morbidity. Techniques for identifying surgical patients with clinically important nutritional deficits are discussed. Retrospective and/or non-randomized clinical studies evaluating the efficacy of perioperative forced feeding are reviewed. These data suggest a possible role for preoperative nutritional support of selected malnourished surgical candidates and provide the rationale for a large-scale nutrition-intervention clinical trial.

Calorie-nitrogen interactions in the parenterally fed primate

To test the hypothesis that nonprotein calorie intake and nitrogen intake are equally important in establishing positive nitrogen balance, weight gain, and serum protein response in the depleted primate treated with total parenteral nutrition (TPN), 10 adult male chair-adapted primates (Macaque fascicularis) were studied. After 10 days of nutritional depletion (nothing by mouth; 5% dextrose with electrolytes administered intravenously) animals were randomized to receive one of four TPN diets for 10 days. The depletion/repletion cycle was repeated, after 1 month of caged free feeding, until all animals had received the four TPN diets. Two levels of nonprotein caloric intake (155% and 100% of primate resting energy expenditure) and two levels of nitrogen intake (200% and 100% of primate nitrogen requirement) were used to make the four different diets. Nitrogen balance (p = 0.01) and serum total iron-binding capacity response (p = 0.02) were significantly influenced by the level of nitrogen intake but not by nonprotein calorie intake, which significantly influenced only weight gain (p = 0.03). Fluid balance was not significantly different for any diet. Fat and protein stores may be selectively repleted in this model by adjusting the nonprotein calorie and nitrogen content of TPN.

Parenteral (glucose or glucose-lipid) vs enteral repletion in malnourished primates: a controlled crossover study

Nutritional repletion with glucose-based total parenteral nutrition (TPN), mixed-substrate (58% lipid, 42% glucose) TPN, and mixed-substrate total enteral nutrition (TEN) was studied in four adult male chair-adapted primates using a crossover design. After 10 d nutritional depletion animals were repleted for 10 d with one of three isocaloric isonitrogenous diets. TPN Diets I and II were identical except that I provided all nonprotein calories as glucose while II provided 58% nonprotein calories as lipid and 42% as glucose. Animals were randomized to I or II as their first repletion treatment. The 20-d depletion-repletion cycle was repeated with the other TPN diet after a 30-d rest period of caged free-feeding. After another 30-d rest period, animals underwent a third 10-d depletion and were repleted with 10 d of TEN (Diet III, identical to II in composition). The three diets resulted in similar weight gain, positive nitrogen balance and fluid balance, and increase in total iron-binding capacity.

Caloric requirements in total parenteral nutrition

Resting energy expenditure (REE) was measured in 100 consecutive total parenteral nutrition (TPN) patients. Only forty-eight percent of the measured REEs were within 90-110% of the predicted Harris-Benedict values. A literature review revealed 191 published guidelines for non-protein caloric requirements of hospitalized TPN patients. These guidelines were appropriately matched and applied to the 100 individual TPN patients. The relationship between the recommended caloric supply and measured caloric expenditure was minimal. The recommendations exceeded measured REE by an average of 1076 +/- 660 kcal/day. These published guidelines were substantially above and below caloric requirements based on measured REE for both fat maintained (130% REE) and fat depleted (150% REE) patients. Following published guidelines rather than standards based on measured REE results in the administration of 6947 excess liters of TPN per year. Improvement in the precision of TPN caloric prescription can be accomplished by using measured REE as a reference base. When published guidelines were compared to prescriptions based on measured REE it was found that published guidelines were inaccurate both overall and individually and a substantial cost savings justifies actual measurement of energy needs.

Treatment effects of parenteral vitamins in total parenteral nutrition patients

To determine the prevalence of abnormal vitamin levels in an adult hospitalized population requiring total parenteral nutrition (TPN) and to assess the effect of routine parenteral vitamin therapy on vitamin levels, we studied 35 general surgical patients. Assays for 12 vitamins were performed both before and after a standard 10-day course of TPN. Patients were given nothing by mouth. The first 25 patients received a daily parenteral vitamin mixture tailored to the recommendations of the Nutrition Advisory Group of The American Medical Association (maintenance dose). The final 10 patients were given a parenteral multivitamin dose providing substantially greater amounts of most vitamins (repletion dose). Only 58% (190/324) of pre-TPN vitamin levels were normal, 25% were low, and 17% were high. No patient had fewer than two abnormal baseline levels. Vitamin levels did not correlate with serum albumin, body weight, or nitrogen balance. After 10 days of treatment, only 39% of low pre-TPN vitamin levels improved; most (45/62) of the low posttreatment levels were low at baseline. The higher repletion dose resulted in a significantly (p less than 0.01) greater percent increase in vitamin A, C, and pyridoxine levels. The prevalence of abnormal vitamin levels in this population is high (42%). Standard parenteral vitamin therapy leads to marginal improvement in abnormally low pre-TPN vitamin levels.

Net protein anabolism with hypocaloric parenteral nutrition in obese stressed patients

Thirteen obese patients requiring parenteral nutrition for postoperative complications were studied prospectively to evaluate the efficacy of hypocaloric, high-protein parenteral feeding. Nonprotein caloric intake averaged 881 kcal/d or 51.5% of the patients' measured resting energy expenditure. Protein intake averaged 2.13 +/- 0.59 g/kg IBW. Serum albumin and TIBC increased significantly (2.8 +/- 0.5 g/dL to 3.2 +/- 0.4 g/dL, p less than 0.01, and 196 +/- 39 micrograms/dL to 248 +/- 49 micrograms/dL, p less than 0.05, respectively), and subjects lost weight (120.0 +/- 60.0 kg to 109.7 +/- 32.5 kg, p less than 0.05). Nitrogen balance studies in eight subjects suggested nitrogen equilibrium or positive balance can be achieved (+2.4 +/- 1.9 g/d). All patients exhibited complete tissue healing of wounds and abscess cavities and closure of fistulae. In obese, protein-depleted surgical patients net protein anabolism and clinical efficacy can be achieved with hypocaloric, high-protein feeding. Abundant endogenous fat stores provide obligatory energy.

Nutritional support of the cancer patient: delivery systems and formulations

Safe, efficacious nutritional support of cancer patients requires a complete assessment to determine each patient's fluid, protein, energy, and micronutrient requirements. The authors review the growing variety of enteral and parenteral formulas and access routes available to provide an individualized nutrient prescription, emphasizing new techniques, their specific indications, and complications.

The relationship of serum cholesterol and vitamin A in hospitalized patients with and without cancer

Interrelationships among circulating levels of cholesterol, vitamin A, and selected transport proteins, as well as other nutritional variables were examined in a large population of hospitalized cancer (CA, n = 94) and noncancer (NONCA, n = 432) patients in order to help clarify a relationship between serum cholesterol and vitamin A. Serum cholesterol and vitamin A levels were positively correlated (r = 0.39; p less than 0.001) in both CA and NONCA groups. One hypothesis that might explain such a relationship was investigated. Results suggest that serum-transport protein levels and nutritional status are important factors that lead to a correlation between serum cholesterol and vitamin A by virtue of their mutual associations with both substances. Results suggest also that NONCA patients may have a more complex relationship of variates to serum-vitamin A levels than CA patients and that low levels of both cholesterol and vitamin A in CA patients may be related more to nutritional status than to the presence of cancer.

Urea nitrogen excretion in chair-adapted primates

To evaluate the temporal pattern of urea excretion in chair-adapted primates (Macaque fascicularis) on continuous total parenteral nutrition (TPN), two groups of five animals were studied. Group I received continuous TPN (75 glucose kcal; 0.56 g nitrogen; and 100 ml fluid per kg per day) while Group II received a single morning isonitrogenous oral meal along with a continuous isovolemic intravenous infusion of 0.45% saline. Urine was collected hourly in group I for 2 days and every 4 hr in group II for 5 days and analyzed for urea content. Time series analysis revealed no periodicity of urea excretion in either group. Six animals were then studied for a total of 46 TPN days to define the relationship between the urea content of a single 3-hr morning urine aliquot and its respective content in a 24-hr collection. A significant linear relationship was found (r = +0.76, p less than 0.01). However, using this relationship, a reasonable estimate (+20%) of measured 24-hr urea output was achieved only 50% of the time using a single 3-hr urea output. Chair-adapted primates maintained on continuous TPN or a single oral meal with continuous saline infusion do not exhibit a periodic pattern of urea excretion. The variability in 3-hr urinary urea output in the chaired primate on continuous TPN does not consistently permit accurate estimation of the coincident 24-hr urinary urea output.

Energy expenditure in malnourished patients with colorectal cancer

To evaluate energy expenditure in patients who have colorectal cancer with varying stages of disease and to examine the possible determinants of energy expenditure in a group of patients with cancer who have the same type of tumor, we studied 73 patients with biopsy proven and pathologically staged adenocarcinomas of the colon and rectum. Resting energy expenditure (REE) was measured by indirect calorimetry and compared with predicted energy expenditure (PEE), which was calculated from the Harris-Benedict formulas. Nutritional and tumor characteristics were examined. Forty-nine percent of patients had abnormal REE (normal = PEE +/- 10%). One quarter of the patients were hypometabolic (REE less than 90% PEE). The abnormalities persisted despite normalization of REE to metabolic body size (kg0.75) or predicted values based on weight, height, age, and sex. There were no differences in nutritional status, as judged by the percent of weight loss and visceral protein levels, between those patients in the hypometabolic, normometabolic, or hypermetabolic categories, and there were no significant relationships between energy expenditure and the tumor burden. The mean duration of disease in the normometabolic group was 4.5 months, while the hypometabolic and hypermetabolic groups had mean durations of 9.5 and 14.2 months, respectively. The tumor site and duration of the disease are important variables in studies of energy expenditure in patients with cancer.

Indirect calorimetry in chair-adapted primates

This paper describes the construction of an indirect calorimeter for measurement of respiratory gas exchange in the chaired primate. Preliminary determinations of energy expenditure and respiratory quotient in five animals under a variety of dietary conditions suggest that this system will prove useful in the laboratory study of primate nutrition, energy metabolism, and cardiorespiratory physiology. Other possible uses and limitations are discussed.

Total parenteral nutrition during pregnancy

Several years ago, most obstetricians would have thought that any disease severe enough to require parenteral nutrition would also lead to infertility or early pregnancy loss. Women with many complex disease states have now been successfully treated by TPN during pregnancy, resulting in favorable outcomes for both mother and fetus. Theoretically, these patients, if not supplied with an adequate amount of essential nutrients by TPN, might have experienced excessive perinatal morbidity and mortality. The difficulties involved with studying maternal-fetal exchange processes in humans leave considerable gaps in our current knowledge about nutritional requirements during normal pregnancy. Some have suggested that subtle degrees of malnutrition may jeopardize normal growth and development. In states of severe protein calorie malnutrition, there remains little doubt that intrauterine growth is diminished. In such cases in which there is poor maternal weight gain, it may be critical to initiate some method of nutritional support. Whereas TPN during pregnancy has been sporadically employed in the treatment of cases of suspected fetal growth retardation, limited experience with this therapy suggests that at present we primarily direct treatment toward patients with specific disease states that are accompanied by overt malnutrition. Parenteral nutrition support should begin only after a period of adequate nutritional assessment and monitoring. If such support is necessary, TPN should be administered by a team of qualified knowledgeable individuals who are very familiar with the techniques. The relatively high rate of premature delivery associated with patients requiring TPN during pregnancy requires the presence of an intensive care nursery in the institution.