Journal of Parenteral and Enteral Nutrition

Our objective was to examine the effect of biosynthetic human growth hormone (BSHGH) on protein and energy metabolism in patients on full intravenous nutrition (IVN). Fifteen patients who had been established on IVN were allocated at random to receive either BSHGH (0.1 mg/kg/day) or placebo daily for 7 days. All patients received the same feeding regimen which contaminated 14 gN, 1000 kcal of glucose and 1000 kcal of fat (Intralipid) daily. The mean nitrogen balance for days 4 to 7 was significantly more positive with BSHGH (7.0 ± 0.6 gN/day) than with placebo (4.4 ± 0.7 gN/ day). The BSHGH group were lighter (53 ± 4.6 kg body weight) than controls (68 ± 5.1 kg), but the difference was not significant. Resting energy expenditure (expressed as percentage of day 1) increased throughout the study in patients receiving BSHGH (day 7, 120.8 ± 5.5%), whereas in patients receiving placebo it remained stable (day 7, 98.9 ± 2.7%). The nonprotein respiratory quotients were similar for BSHGH (mean days 4-7, 0.94 ± 0.04) and placebo (mean days 4-7, 0.93 ± 0.01) (p > 0.05). This study demonstrates more positive nitrogen balance, which may in part be due to different substrate loads, and an increase in energy expenditure in patients receiving BSHGH. (Journal of Parenteral and Enteral Nutrition 14:437-441, 1990).

The effects of a fat and glutamine-free orally administered total parenteral nutrition (TPN) solution on intestinal mucosal mass, morphology, barrier function, and cecal bacterial population levels were measured in CD-1 mice. Ileal mucosal protein content decreased by 63% (p < 0.01) in the oral TPN-fed mice, although they gained weight on this diet. These TPN-fed mice also exhibited changes in mucosal structure and the normal ecology of their cecal microflora was disrupted leading to overgrowth with Gram-negative enteric bacilli. These changes in intestinal mucosal mass, morphology, and gut bacterial ecology were associated with an increased incidence of bacterial translocation (BT) (TPN group 70% BT us control group 15% BT: p < 0.01). The administration of cellulose fiber or kaolin (bulk-forming agents), but not of citrus-pectin (a fully-fermentable, nonresidue fiber) reduced the incidence of BT in the TPN-fed mice to control levels. The beneficial effects of these bulk-forming agents appeared to be due to their ability to prevent TPN-induced disruption of the intestinal microflora and alterations in intestinal morphology, even though they did not prevent ileal mucosal protein levels from decreasing. These results suggest that the administration of bulk forming agents will prevent the loss of intestinal barrier function against luminal bacteria that occurs in mice fed an oral TPN solution. (Journal of Parenteral and Enteral Nutrition 14:442-447, 1990)

To determine whether intravenous carnitine can improve nutritional indices, neonates requiring parenteral nutrition were randomized into carnitine treatment (n = 23) and control (n = 20) groups. Observed plasma lipid indices, carnitine and nitrogen balances, and plasma carnitine concentrations were not different in the prestudy period. Under standardized, steady-state conditions, 0.5 g/kg Intralipid was administered intravenously over 2 hr prior to carnitine administration, after infants received 7 days of 50 μmol/kg/day, and after a second 7 days of 100 μmol/kg/day of continuous intravenous L-carnitine as part of parenteral nutrition. Triglyceride (TGY), free fatty acid (FFA), acetoacetate (AA), β-hydroxybutyrate (BOB), and plasma carnitine concentrations were measured prior to and at 2, 4, and 6 hr after the initiation of the lipid bolus. Twenty-four-hour urine collections for nitrogen and carnitine balance were obtained on days 7 and 14. Neonates receiving carnitine had significantly greater concentrations of plasma carnitine on days 7 and 14 (p < 0.001). Greater nitrogen (p < 0.05) and carnitine (p < 0.001 ) balances and weight gain (week 2, p < 0.05) were found in the carnitine-supplemented group when compared with controls. On day 14, (BOB + AA)/ FFA ratios were significantly higher (p < 0.05), and peak TGY concentrations and 6-hr FFA concentrations were significantly lower (p < 0.05) in the treatment group. Carnitine supplementation was associated with modest increases in growth and nitrogen accretion possibly by enhancing the neonate's ability to utilize exogenous fat for energy. (Journal of Parenteral and Enteral Nutrition 14:448-453, 1990)

Malnutrition occurs commonly in patients with acquired immunodeficiency syndrome (AIDS). The efficacy of nutritional support is unknown. A prospective, longitudinal study was conducted to determine the effect of prolonged total parenteral nutrition on body composition in 12 AIDS patients. Five patients were malnourished because of problems with food intake or absorption, while seven had systemic infections, with or without a malabsorption syndrome. The AIDS patients gained body weight and body fat content in response to total parenteral nutrition, while mean body cell mass, estimated as total body potassium content, was unchanged. However, all five patients with altered intake or absorption had significant repletion of body cell mass which was significantly different from the patients with systemic infections. Calorie and nitrogen intake did not differ between the two groups. It is concluded that body mass repletion is possible in AIDS patients in whom malabsorption is the major pathogenetic factor in producing malnutrition and is less successful in patients with serious ongoing systemic diseases. Thus, the response to nutritional support is dependent on the particular clinical circumstances. (Journal of Parenteral and Enteral Nutrition 14:454-458, 1990)

Intravenous lipid emulsions depress lymphocyte proliferative responses and granulocyte function at concentrations found in the blood circulation during their administration. The effects of Intralipid, a widely used intravenous lipid emulsion, were measured on immunoglobulin production in vitro by pokeweed mitogen-activated lymphocytes as a test of B-cell function. Intralipid decreased IgG, IgM, and IgA production at soybean oil triglyceride concentrations of 2.5-20 mg/ml occurring in the blood circulation during Intralipid infusion. The effects on IgM and IgA production were highest and that on IgG production lowest. Hydrocortisone-sensitive and concanavalin A-inducible suppressor cells were more sensitive to Intralipid than other cell populations. In vivo Ig production may not be equally disturbed, inasmuch as Intralipid concentrations in the lymph nodes and the spleen may be lower than in the blood circulation. However, care should be taken to prevent Intralipid concentrations from becoming high enough to depress immune responses. (Journal of Parenteral and Enteral Nutrition 14:459-462, 1990)

Since the addition of lipid to intravenous feeding formulas, animal and human studies have shown impairment of the reticuloendothelial system (RES) due to slow rates of clearance and gradual accumulation of long chain triglycerides (LCT) in the liver. Medium chain triglycerides (MCT) accumulate only minimally in the liver and do not impair the RES. However, results from animal studies using technetium sulfur colloid (TSC) to assess RES function have been inconclusive. The present study reevaluates RES function after lipid infusion in guinea pigs as measured by organ distribution of TSC. Guinea pigs were fed 300 kcal/kg/day of total parenteral nutrition (TPN) for 2.5 days, with 50% of nonprotein calories as fat in the form of LCT or MCT, then injected intravenously with 2.5 or 25 μCi of TSC, and uptake by liver, spleen, and lungs was determined. Liver, lungs, and spleen all increased in size after TPN with LCT or MCT. Liver TSC uptake was significantly affected by the dose of TSC (p < 0.05), with the high dose probably inducing an increased capacity of the liver to clear TSC from the blood. Liver uptake was not influenced by diet, but feeding MCT did significantly stimulate lung uptake of TSC (p < 0.0001). This suggests that the hepatic TSC uptake system is not saturable, and may not be an appropriate measure of Kupffer cell function since the colloid is not phagocytosed. However, TSC blood clearance remains an excellent prognostic indicator for bacteremia and mortality in humans, and is useful for measuring global RES function. (Journal of Parenteral and Enteral Nutrition 14:463-466, 1990)

Previous study demonstrated that patients who received total parenteral nutrition (TPN) with standard intermittent infusion of long chain triglyceride (LCT) at 0.13 g kg^-1hr^-1 over 10 hr for each of three days showed a significant decline in ⁹⁹Tc-sulfur colloid (TSC) clearance rate by the reticuloendothelial system (RES). The present studies evaluated eight patients who received the same total lipid dose of LCT infused continuously as in a three-in-one admixture, and another nine patients receiving the same amount of fat as a medium chain triglyceride (MCT)/LCT (75%/25%) emulsion intermittently over 10 hr at 0.13 g kg^-1hr^-1 for three consecutive days. Patients were given continuous total parenteral nutrition (TPN) comprised of protein, 1.5 g kg^-1day^-1, and dextrose, 4.5 g kg-1day-l. RES function was examined by measuring the clearance rates of intravenously injected TSC while receiving TPN containing only protein and dextrose, and again after three days of fat infusion. Mean (±SEM) clearance rate constants before and after continuous LCT infusion were 0.38 ± 0.09 and 0.41 ± 0.08 min^-1, respectively, while those before and after intermittent MCT/LCT infusion were 0.50 ± 0.18 and 0.73 ±- 0.24 min^-1, respectively. In contrast to intermittent LCT infusion, the administration of continuous LCT or an intermittent MCT/LCT mixture does not impair TSC clearance by the RES. These findings suggest that condensing the daily period of LCT infusion at standard dosage may exceed the rate of metabolic utilization, resulting in increased fat removal and diminished TSC uptake by the RES. The provision of fat principally as MCT or by a continuous mode of administration may enable adequate metabolism of lipid emulsion without RES dysfunction, and so may be of particular benefit in critically ill or septic patients. (Journal of Parenteral and Enteral Nutrition 14: 467-471, 1990)

Neutrophils from cord blood of healthy term infants were isolated and incubated for 30 min with varying concentrations of intravenous lipid emulsion (ILE) solution (4, 8, 20 mg/ml). In vitro assay of chemotaxis was performed after incubation for 120 min with endotoxin-activated serum (EAS). Neutrophil random motility was unchanged after ILE incubation yet chemotactic factor (EAS)-stimulated motility was significantly reduced in a dose-related pattern. (Journal of Parenteral and Enteral Nutrition 14:472-473, 1990)

Clinical suspicion and venographic conformation were used to diagnose 15 cases of superior vena caval obstruction (SVCO) in 107 home parenteral nutrition (HPN) patients over 379 cumulative years of HPN (3.9 cases/100 patient-years). Patients with SVCO had been on HPN a mean of 51.5 months and had used 6.2 (range 1-50) central catheters, including short- and long-term, before SVCO was diagnosed. The frequency of inflammatory bowel disease (IBD) with SVCO was approximately the same as that in our general HPN population. Positive blood cultures were present immediately preceding the diagnosis of SVCO in 40% (six of 15) of cases. Atypical line placements were noted in two cases. The most common management strategies employed were conversion to enteral feedings in five patients and placement of a new catheter directly into the right atrium by thoracotomy in another five patients. Two of the five with right atrial catheters experienced a postpericardiotomy syndrome (fever, pericardial rub, and pulmonary infiltrates) that responded promptly to indomethacin. The most significant long-term sequela of SVCO was the need for a left jugular vein to right atrial appendage bypass in one patient with chronic venous congestion from her SVCO. Once the SVCO is confirmed, systemic heparinization provides immediate antithrombotic effect and minimizes the risk of pulmonary embolism. The use of streptokinase may result in rapid thrombolysis. ( Journal of Parenteral and Enteral Nutrition 14:474-479, 1990)

Patients receiving cytoreductive therapy and bone marrow transplantation (BMT) are known to develop marked protein catabolism. To assess the contribution of whole body protein breakdown, amino acid oxidation and incorporation into proteins, plasma leucine kinetics (1-¹³C-leucine infusion technique) were determined in six patients five times within 14 days before and after cytoreductive therapy (Cyclophosphamide and total body irradiation) and marrow transplantation. Nitrogen balance became negative (—0.20 ± 0.04 g/ Kg/24 hr) after cyclophosphamide (p < 0.01) and was -0.25 ± 0.05 g/Kg/24 hr 7 days after BMT in spite of total parenteral nutrition.

Plasma leucine concentration increased after BMT by 67% (p < 0.0015). Leucine plasma appearance was 1.20 ± 0.15 μmol/ kg/min before treatment, it increased slightly and transiently after cyclophosphamide, and increased again from day 5 to day 7 after BMT (p < 0.01), suggesting increased protein breakdown. Leucine oxidation increased from 0.27 ± 0.07 before therapy to 0.97 ± 0.16 μmol/kg/min (p < 0.02) after cyclophosphamide and BMT. Nonoxidative leucine disappearance rate decreased slightly from 0.92 ± 0.08 to 0.75 ± 0.16 μmol/kg/min after BMT (ns). Leucine metabolic clearance rate decreased from 11.8 ± 1.65 before therapy to 6.9 ± 0.70 ml/kg/min (p < 0.02) after cytoreductive therapy. After BMT it increased again to 9.9 ± 1.5 ml/kg/min (p < 0.02). The results demonstrate that patients undergoing cytoreductive therapy and bone marrow transplantation develop negative nitrogen balance due to increased protein breakdown associated with increased leucine oxidation and increased metabolic clearance rate. Leucine incorporation into proteins (protein synthesis) was not altered inspite of an increase in plasma leucine concentration. ( Journal of Parenteral and Enteral Nutrition 14:480-484, 1990)

Twenty pregnant patients needing nutritional support for various indications received hypercaloric, hyperosmotic, "3 in 1," peripheral parenteral nutrition as a bridge to enteral therapy. This system, named total peripheral parenteral nutrition, was evaluated as to tolerance and efficacy in pregnant patients. Patients were in various stages of pregnancy and had an average weight loss of 10.4 pounds prior to admission. Patients were maintained on total peripheral parenteral nutrition for an average of 5 days and gained an average of 4.1 pounds. Good tolerance with minimal side effects of the treatment was noted. Intravenous sites were changed an average of 1.1 times per patient during the course of therapy and only one serious complication was noted in 20 patients. Patients were followed through delivery and this information is presented. Total peripheral parenteral nutrition appears to be an acceptable alternative to conventional total parenteral nutrition to pregnant patients needing nutritional support. These hypertonic solutions can supply total caloric/metabolic needs without unacceptable side effects. (Journal of Parenteral and Enteral Nutrition 14:485-489, 1990)

Rats were fed a 0% casein diet for 1 week, with or without enteral or parenteral administration of essential amino acids, or a 25% casein diet, in one group supplemented with 5-fluorouracil treatment. Ninety minutes before sacrifice the rats were given a tracer of [³H]orotic acid. Incorporation into the acid soluble fraction, RNA, and DNA was determined in liver, small intestine, bone marrow, and kidney. Nucleotide profile was examined in liver and intestine. Protein deficiency caused inter alia a decrease in body weight; a decrease in RNA/ DNA ratio and an increase in the specific RNA labeling in liver and kidney; an altered nucleotide profile in the liver; an increase in the nucleotide/DNA and RNA/DNA ratios and a decrease in the specific labeling of the acid soluble fraction, RNA, and DNA in the bone marrow. These changes were prevented to the same extent by giving essential amino acids, either orally or intravenously. The minor changes in intestinal nucleotide profile in protein deprivation were prevented to a slightly larger extent by amino acids orally than parenterally. 5-Fluorouracil treatment gave a decrease in the RNA/DNA ratio in the liver and kidney but an increase in the nucleotide/DNA and RNA/DNA ratios in the bone marrow. Nucleotide profiles were unaltered. The amount of DNA per gram of tissue decreased in bone marrow and increased in kidney. Parenteral administration per se resulted in almost no changes. (Journal of Parenteral and Enteral Nutrition 14:490-496, 1990)

Whether tryptophan in the usual dose found in total parenteral nutrition (TPN) solutions caused a decrease in food intake was investigated in 16 adult male Fischer 344 rats. A jugular venous catheter was placed, and patency was maintained with a continuous infusion of normal saline at 3 ml/hr. After a 10-day recovery period, eight normal saline control rats were sacrificed and the remaining eight rats were given a parenteral nutrition solution (PN-50) at 3 ml/hr, providing 50% of the rat's daily energy requirement as 5% dextrose and 2% Intralipid. On day 14, study rats were further divided into two subgroups. Subgroup A received tryptophan (180 mg/day) added to the solution for 5 days. Subgroup B received the serotonin-receptor blocker, cyproheptadine 24 mg/kg/day, continuously for 5 days, and on day 16, tryptophan (0.25% = 180 mg/kg/day) was added to the solution for 3 days. Chow and water was continuously available and spontaneous food intake was measured daily. Study rats were sacrificed on day 19. Plasma amino acids and insulin and whole brain biogenic amines were compared with those in control rats using Student's t-test. With administration of PN-50, spontaneous food intake decreased to about 60% compared with the pre-PN level. The addition of tryptophan to the continuous infusion of PN-50 did not decrease spontaneous food intake further. Compared with pre-PN levels there were no changes in plasma immunoreactive insulin, plasma tryptophan concentration, or plasma Trp/Val+Leu+Ile+Phe+Tyr ratio, even though the concentration of tryptophan (0.25%) which was added to the PN solution was four times higher than that usually found in standard TPN solution. Furthermore, the administration of cyproheptadine did not increase spontaneous food intake. The data thus question the role that tryptophan, in its usual doses in TPN solution, is thought to have in the regulation of spontaneous food intake. (Journal of Parenteral and Enteral Nutrition 14:497-500, 1990)

501 ABSTRACT. Several studies have reported that gastrointestinal (GI) intolerance symptoms are the limiting factor to enteral alimentation in the immediate postoperative period and often the reason for resorting to total parenteral nutrition (TPN). We postulated that Reabilan HN (a recently developed small peptide-based formula, in part obtained by enzyme hydrolysis of proteins) might be better absorbed and better tolerated so as to avoid the need for TPN. Accordingly, 19 patients undergoing major abdominal surgery were randomly assigned to receive Reabilan HN via jejunostomy or an equicaloric isonitrogenous TPN regimen. Both were begun 6 hr postoperatively at 25 ml/hr and increased by 25 ml/hr at 12-hr intervals up to the rate providing 1.5 times the calculated REE. GI tolerance to enteral feeding was excellent during the first three postoperative days, allowing the progression of the feeding rate to 99% of goal. During the next 3 days (starting on average 1.7 days after the return of bowel sounds), GI intolerance symptoms required a reduction in feeding rate to 52% on average. Subsequently, the symptoms resolved and the feeding rate reached 96% of goal. Although overall mean daily calorie and nitrogen intakes were lower for the enteral than for the TPN group (79.6 ± 10.2% vs 94.6 ± 3.8% of goal; p < 0.01), the enteral group was nevertheless in positive caloric and nitrogen balance, and maintained similar serum albumin, prealbumin, and plasma transferrin levels. Average daily cost of supplies was $44.36 for enteral us $102.10 for parenteral nutrition (p < 0.001). We conclude that enteral feeding using this formula is well tolerated and cost-effective in the immediate postoperative period. Further studies of GI motility in the postoperative period, specifically during the 2 to 3 days following the return of bowel sounds, seem crucial to achieving further progress in postoperative enteral feeding. (Journal of Parenteral and Enteral Nutrition 14:501-507, 1990)

Diarrhea, constipation and subsequent laxative use are chronic problems in long-term enterally fed patients. We have conducted a double-blind randomized crossover study to evaluate the effects of two enteral formulae (Enrich, 12.8 g of dietary fiber per 1000 kcal and Ensure, fiber-free) on stool frequency, fecal weight, laxative use, gastrointestinal tolerance and bowel function in chronic care tube-fed patients. Twenty-eight subjects (24 male, 4 female) completed the study. Mean daily number of stools and mean daily fecal wet weight in Enrich-fed patients were not significantly different from those of patients receiving Ensure. Ensure-fed patients required significantly more laxatives (p = 0.02) than those receiving Enrich. There were 26 reports of diarrhea in the Ensure-fed group as compared to 6 in the Enrich-fed group, and this difference was significant (p = 0.006). Reporting rates for constipation were not significantly different in the two groups. At the end of the study, the bowel function of 57.1% of patients receiving Enrich was improved when compared with that of 14.3% of Ensure-fed patients, and this difference was significant (p = 0.005). These results suggest that the addition of dietary fiber to enteral formulae improves gastrointestinal tolerance and bowel function, and reduces laxative use in long-term enterally fed patients. (Journal of Parenteral and Enteral Nutrition 14:508-512, 1990)

Inadequate drug plasma levels have been associated with the administration of phenytoin with enteral feedings through nasogastric (NG) tubes. It is demonstrated in this study that loss of phenytoin to tubing is a function of pH. Nonionized phenytoin is irreversibly bound to NG tubing from solution at the pH of enteral nutrient solutions while this is not the case for anionic phenytoin in unbuffered water or saline. In experiments pulsing phenytoin through glass us NG tubing perfused with buffer at varying pH, reversible loss to tubing was observed at high pH while irreversible loss was observed at low pH. In addition, the irreversible loss of phenytoin was greater in NG tubing than glass particularly at low pH. It is suggested that in those cases where tubing is placed into the duodenum, inadequate gastrointestinal residence time for dissolution of phenytoin solid and suspension dosage forms coupled with irreversible drug loss from solution to NG tubing will result in decreased phenytoin absorption and subsequently lower drug plasma levels. (Journal of Parenteral and Enteral Nutrition 14:513-516, 1990)

Since the measurement of total nitrogen output (TNO) is not routinely determined in the clinical setting, its level is frequently estimated using formulas based on the urinary urea nitrogen excretion (UUN). We measured TNO in 124 surgical patients over 990 days (TNO, 19.22 ± 8.72 g N/ day; total urinary nitrogen (TUN) 18.17 ± 8.70 g N/day; UUN, 15.17 ± 7.70 g N/day; mean gastrointestinal nitrogen (MGIN) 0.68 ± 0.49 g N/day; integumental nitrogen (ITGN), 0.34 ± 0.08 g N/day) and compared the results with the daily estimations using three different formulas: formula A, UUN + 4; formula B, UUN x 1.20 + 1.05, where 1.20 is the reciprocal of the mean ratio UUN/TUN and 1.05 the mean extraurinary nitrogen losses; and formula C, UUN x 1.0986 + 2.55, derived from the regression analysis of UUN us TNO. TNO estimated by these formulas were 19.17 ± 7.70, 19.26 ± 9.24, and 19.22 ± 8.70 g N/day, respectively. The regression analyses of the estimated TNO from the three formulas versus the measured TNO indicated that formulas A, Band C were equally accurate in estimating TNO over the entire range of UUN. However, when only values of UUN ≥ 30 g N were considered, a modified formula A (UUN + 6) was the best predictor of TNO. Daily audits of the differences between the estimated and measured TNO showed comparable results for the three formulas. In 28.4 to 31.1 % of the observed days the differences were higher than ± 2 g N/day, an error which is not acceptable when estimating the protein requirements in many clinical conditions. Thus, the formulas for estimating TNO are only clinical approximations of the nitrogen losses. (Journal of Parenteral and Enteral Nutrition 14:517-522, 1990)

The relative in vivo availability of gentamicin when administered by two different intravenous methods was evaluated in patients treated in a surgical intensive care unit in a randomized, prospective, crossover study. Each patient received gentamicin therapy via intravenous piggyback (IVPB) and in-line burette (ILB) methods. In the IVPB method, the drug was mixed in 5% dextrose in water (D5W) and infused intermittently. In the ILB method, the drug was mixed using the patient's total nutrient admixture (TNA) solution as the diluent in an ILB, which was inserted between the TNA bottle and its administration set and infused intermittently. A serial sampling of four sets of serum concentrations of the gentamicin was obtained. Pharmacokinetic parameters (K_el, Vd, and a maximum serum concentration) were calculated from the four sets of concentrations collected per patient. The IVPB method yielded mean values of K_el, Vd, and C_15mg/kg of 0.13 hr^-1, 0.39 liter/kg, and 5.1 μg/ml, respectively. The ILB method yielded mean values of K_el, V_d, and C_1.5mg/kg of 0.14 hr ^-1, 0.34 liter/kg, and 5.6 μg/ml, respectively. A t-test for paired samples was applied to these mean values. Significant difference was not found (p > 0.05). The intermittent infusion of gentamicin, using TNA as the diluent and an ILB, produced equivalent serum concentrations when compared with D5W as the diluent. (Journal of Parenteral and Enteral Nutrition 14:523-526, 1990)

A spectrophotometric enzymatic assay for plasma carnitine concentrations has been automated on the Monarch 2000. Prior to the assay, each plasma sample was divided into three fractions, ie, free carnitine, acid-soluble carnitine and total carnitine, in order to determine the concentrations of both free and esterified carnitine. Using the method developed by Tachikawa et al (Seikagaku 56:998, 1984), each of the samples was then chromatographed on an anion exchange resin to eliminate those compounds which could adversely impact the accuracy of the enzymatic assay for carnitine. After the completion of these preparatory steps, 32 specimens were assayed in less than 16 min on the Monarch 2000 with a high degree of both accuracy and precision. The assay was linear over a wide concentration range (5.0-80 μmol/liter), with the lower limit of sensitivity being 5.0 μmol/liter. The coefficient of variation (CV%) of the within run precision was 2.1%, 2.8%, and 6.7% for the determinations of free carnitine, acid-soluble carnitine, and total carnitine, and 17.4% and 27.8% for the calculated values of short-chain and long-chain acylcarnitines, respectively. The CV% of the between run precision for the same fractions was 6.5%, 2.7%, 3.8%, 14.2%, and 14.3%, respectively. When authentic L-carnitine was added to the plasma, the mean recovery rate was 94.7 ± 11.0%. Reference values were determined using plasma obtained from 40 healthy adult volunteers. (Journal of Parenteral and Enteral Nutrition 14:527-532, 1990)

The percutaneous endoscopic gastrostomy (PEG) has replaced the surgical gastrostomy (GT) on our service. We reviewed our data in an effort to determine relative efficacy and cost effectiveness of the two techniques. Thirty-five patients with PEGs were matched for age and diagnosis with 35 patients with GTs done by the same surgical service. PEGs were done in the endoscopy suite; GTs were done in the operating room: both under local anesthesia. Patients in PEG and GT groups were comparable in sex, diagnosis, and age. The PEG took less time to insert (15.3 vs 25.4 min, p < 0.001). Major postoperative morbidity was similar with 10 systemic complications for each group and 11 deaths for the PEG us 12 deaths for the GT group (at 90 days). Minor morbidity was higher for the PEG group with nine complications vs 1. Estimated cost for PEG was half the cost of GT. Hospital stay for the two groups was similar (36 vs 45 days, p > 0.1), but postop stay for the PEG group tended to be shorter (17 us 24 days, p < 0.08). The PEG is faster and cheaper to insert than the GT, however major morbidity and mortality are the same. (Journal of Parenteral and Enteral Nutrition 14:533-534, 1990)

Although fructose is widely regarded as an insulin-independent fuel source, its in vivo conversion to glucose represents a theoretical limitation to its clinical usefulness in diabetics, particularly if given in large doses. To determine whether small amounts of fructose can be well utilized in the setting of insulinopenia, we administered a low-dose fructose infusion (4.2 g/hr) to a fasting type 1 diabetic patient receiving continuous subcutaneous insulin at a dose that had previously maintained stable euglycemia for 72 hr (plasma glucose = 80-110 mg/dl). Despite the low infusion rate (<20% of calorie requirement), fructose caused an immediate and marked rise in plasma glucose (to 370 mg/dl after 27 hr). Glucose loss in the urine and accumulation in plasma could account for fully half of the administered hexose load. Thus, the utilization of even small quantities of exogenous fructose is profoundly impaired under hypoinsulinemic conditions. It is misleading to regard fructose as a truly insulin-independent fuel source. (Journal of Parenteral and Enteral Nutrition 14:535-537, 1990)

A challenging problem facing the clinician is the management of critically ill patients in whom repeated attempts at weaning from mechanical ventilation are unsuccessful. The difficulty weaning these patients from the ventilator can be augmented in the presence of detraining of respiratory muscles, malnutrition, stress and the metabolic response to iniury, and/or immobilization. An understanding of basic concepts of established tenets of exercise physiology and of nutritional support will allow their application to respiratory muscle function with the goal of facilitating the endurance and strength of respiratory muscles needed to sustain spontaneous ventilation. (Journal of Parenteral and Enteral Nutrition 14:538-542, 1990)

Medium-chain triglycerides (MCT) are an important component of an enteral ketogenic diet for seizure control. Previously, it was difficult to maintain ketosis when parenteral (iv) nutrition therapy was necessary. The use of iv MCT in a 5-year-old girl with Lennox-Gastaut syndrome who had diarrhea and dehydration is reported. Conventional 20% iv fat emulsion (long-chain triglycerides, LCT) and dextrose free hyperalimentation (HAL) in a 4:1 ketogenic ratio did not maintain adequate ketosis during bowel rest. Compassionate use of iv MCT (Clintec Nutrition) infused as a 70:30 MCT/ LCT ratio plus HAL maintained moderate ketosis. Seizures were well controlled during the iv MCT regimen, which allowed normal daily functioning. Complications included abnormal liver function tests and severe iron deficiency anemia of unknown etiology. Serum triglyceride and cholesterol levels increased to 1717 mg/dl and 614 mg/dl, respectively, but decreased with a reduction of lipid infusion and use of an antihyperlipemic drug. Nutritional status was maintained. In this case, iv MCT proved to be a relatively safe and effective short-term method of continuing parenteral nutrition while maintaining ketosis for seizure control. (Journal of Parenteral and Enteral Nutrition 14:543-545, 1990)

A new method which provides immediate fixation of a cuffed central venous catheter is described. The cuffed polyurethane catheter has a detachable hub which allows the creation of a second small tunnel distal to the cuff using the wire and the vein dilator. As the catheter exits from a "pinhole," immediate fixation is assured and is independent of tissue healing. (Journal of Parenteral and Enteral Nutrition 14:546-547, 1990)