Physical characteristics of total parenteral nutrition bags significantly affect the stability of vitamins C and B1: a controlled prospective study

BACKGROUND: Vitamin degradation occurring during the storage of total parenteral nutrition (TPN) mixtures is significant and affects clinical outcome. This study aimed to assess the influence of the TPN bag material, the temperature, and the duration of storage on the stability of different vitamins. METHODS: Solutions of multivitamin and trace elements at recommended doses were injected into either an ethylvinyl acetate (EVA) bag or a multilayered (ML) bag filled with 2500 mL of an identical mixture of carbohydrates (1200 kcal), fat (950 kcal), and amino acids (380 kcal). The bags were then stored at 4 degrees C, 21 degrees C, or 40 degrees C. Concentrations of vitamins A, B1, C, and E were measured up to 72 hours after compounding, using high-pressure liquid chromatography. RESULTS: Ten percent to 30% of vitamin C degradation occurred within the first minutes after TPN compounding. Vitamin C was more stable in ML bags (half-life: 68.6 hours at 4 degrees C, 24.4 hours at 21 degrees C, and 6.8 hours at 40 degrees C) than in EVA bags (half-life: 7.2 hours at 4 degrees C, 3.2 hours at 21 degrees C, and 1.1 hour at 40 degrees C). Moreover, appearance of dehydroascorbic acid in the TPN mixture did not compensate for vitamin C losses. Vitamin B1 was stable at 21 degrees C, but a 43% loss occurred at 40 degrees C after 72-hour storage in EVA bags. The other vitamins were stable in the TPN mixture stored in both bags at any temperature and without daylight protection. CONCLUSIONS: Degradations of vitamins C and B, are significantly reduced in ML bags compared with EVA bags. To prevent vitamin C deficiencies, its initial dose should be adapted to its degradation rate, which depends on the TPN bag material, the ambient temperature, and the length of time between TPN compounding and the end of infusion to the patient.     

Assessment of ascorbic acid stability in different multilayered parenteral nutrition bags: critical influence of the bag wall material

BACKGROUND: The recent development of multilayered bags has minimized ascorbic acid oxidation in parenteral nutrition (PN) admixtures. However, the gas-barrier property of multilayered bags depends on their plastic material. This study compared ascorbic acid stability in different multilayered bags under experimental conditions. METHODS: Oxygen permeability of a newly developed 6-layered bag (6-L) was compared with a highly mechanical-resistant 3-layered bag (3-L(R)) and a highly flexible 3-layered bag (3-L(F)) using gas chromatography. Ascorbic acid stability was assessed by iodine titration in bags filled with 2.5 L H(2)O and 40 g carbohydrates after setting residual O(2) content at < or =1 or > or =5 ppm. The effect of storage at 4 degrees C, 21 degrees C, and 40 degrees C on ascorbic acid stability was assessed over 48 hours in a complete PN admixture (ie, 330 g carbohydrates, 100 g lipids, 96 g amino acids and trace elements) using high-pressure liquid chromatography. RESULTS: Oxygen permeability was markedly reduced in 6-L bags (0.5 mL O(2) /m(2)/d) compared with 3-L(R) (150 mL O(2) /m(2)/d) and 3-L(R) (1500 mL O(2)/m(2)/d). Accordingly, ascorbic acid was more stable in 6-L bags (half-life [T(1/2)] = 16 days up to 40 degrees C) than in 3-L(R) (T(1/2) = 9 days at 4 degrees C, 47 hours at 21 degrees C and 29 hours at 40 degrees C) and 3-L(F) (T(1/2) = 15 hours at 4 degrees C, 10 hours at 21 degrees C, and 6 hours at 40 degrees C). During the first 6 hours after PN admixture compounding, an additive ascorbic acid loss of 4.6 +/- 0.5 mg/L/ppm O(2) occurred because of residual O(2) in the bag. CONCLUSIONS: The new combination of plastic layers and careful O(2) monitoring during the filling process allowed near to complete prevention of ascorbic acid degradation in multilayered PN bags during 48 hours, regardless of the storage temperature.     

The stability of thiamine in total parenteral nutrition mixtures stored in EVA and multi-layered bags

The compounding of complete total parenteral nutrition (TPN) mixtures into big bags with extended shelf-lives has been made more possible by the introduction of reduced gas permeable bags, using multi-layered plastic laminates. Since this produces a highly reduced chemical environment, the stability of thiamine; which degrades by reduction, may be compromised. It was the purpose of this study to investigate the degradation of thiamine at two different concentrations in TPN mixtures containing different commercial amino acid sources stored for extended periods in EVA or multi-layered bags. Results indicated that thiamine was unstable in mixtures containing Freamine III 8.5%, a metabisulphite-containing amino acid infusion, but was relatively stable in mixtures containing Vamin 14, Aminoplex 12 or Eloamin 15% as the amino acid source. Degradation of thiamine in Freamine III 8.5%-containing mixtures stored in multi-layered bags was more rapid than in EVA bags. Degradation rate was not greatly influenced by thiamine concentration. Results indicate that thiamine is stable in complete TPN mixtures for periods of at least 28 days in multi-layered bags, provided metabisulphite containing amino acid infusions are avoided. The shelf-life of complete mixtures containing Freamine III should be restricted to ensure patient receive minimum acceptable daily thiamine requirements.     

Stability of ascorbic acid in a standard total parenteral nutrition mixture

We investigated the stability of ascorbic acid (AA) and the sum of AA plus dehydroascorbic acid (TAA) in a total parenteral nutrition (TPN) mixture that contained 1000 ml Vamin 14, 1000 ml glucose 30%, 500 ml Intralipid 20%, potassium phosphate, a multivitamin preparation (Cernevit) and trace elements. We used a spectrophotometer to measure AA and TAA. AA decreased from 42.2 (+/-0.9) mug/ml to 6.8 (+/-0.2) mug/ml in 7 days. Over the same time the concentration of TAA decreased from 42.2 (+/-0.5) mug/ml to 35.9 (+/-0.6) mug/ml, i.e. 63.3 (+/-1.2)% of the original concentration. When the solution was stored in glass bottles and saturated with nitrogen or when trace elements were omitted, the concentration decreased by only 25.2 (+/-0.2)% and 23.8 (+/-1.6)% respectively over 7 days. The influence of oxygen, lipids, trace elements and underfilling the bag was also investigated. We conclude that it is acceptable to prepare these bags in advance and to store them for 7 days at 2-4 degrees C.     

Factors influencing the stability of ranitidine in TPN mixtures

The stability of ranitidine in TPN mixtures has been widely studied with varying results. The evidence suggests that ranitidine is unstable and should be added within 24 h of administration, although other reports indicate ranitidine is stable for at least 14 days. The causes of ranitidine degradation in TPN mixtures were therefore studied in mixtures without fat emulsion using a stability-indicating HPLC method. The results indicated that the stability of ranitidine at 5 degrees C depended on the commercial source of amino acid, additives and type of bag used. The principle mechanism of degradation was identified as oxidation. Ranitidine was more stable in EVA bags in the absence of the trace element additive, which appeared to accelerate ranitidine oxidation. Ranitidine was most stable in mixtures compounded in multi-layered bags. The results suggest TPN mixtures with ranitidine in multi-layered bags could be assigned shelf lives of at least 14 days at 5 degrees C, depending on the amino acid infusion used in the regimen.     

Practical aspects of multichamber bags for total parenteral nutrition

PURPOSE OF REVIEW: Ready-to-use all-in-one admixtures are standards for short and long-term parenteral nutrition. Their limited stability does not allow storage over prolonged periods of time. Multichamber bags represent industrially manufactured near complete standard parenteral nutrition premixes with extended shelf lives. This review focuses on the characterization of multichamber bags, their influence on parenteral nutrition practice, the need for individual parenteral nutrition compounding, and the role of the pharmacist in the nutrition team. RECENT FINDINGS: The all-in-one admixture concept, its correlation with parenteral nutrition effectiveness, safety, and pharmaceutical issues are reviewed. Multichamber bags, the bag material, their use and practical handling are addressed. SUMMARY: Newly developed container materials are mainly responsible for the increased stability of multichamber bag parenteral nutrition premixes. Multichamber bags are used for (standard) parenteral nutrition in adults. Multichamber bags cannot eliminate individualized all-in-one parenteral nutrition compounding. Pharmaceutical assistance with expertise in compatibility and stability is mandatory for the nutrition team to implement and control good parenteral nutrition practices, e.g. to convert multichamber bags into complete ready-to-use all-in-one admixtures or to compound individualized regimens. The incorporation of additional components into parenteral nutrition admixtures (pharmaconutrients, drugs) must rely on documented compatibility with the parenteral nutrition admixtures. Multichamber bags have their advantages and limitations. Studies on the effectiveness and costs of multichamber bags are needed to meet the expectations of pharmacists, physicians, nurses, and industry for optimal parenteral nutrition in patients.     

Extraction of diethylhexylphthalate from total nutrient solution-containing polyvinyl chloride bags

Total nutrient solution (TNS) is a new method for delivering total parenteral nutrition (TPN) by admixing dextrose, amino acids, and lipids in a single container. Recommendations are to use nonpolyvinyl chloride (PVC) containers for admixture of these solutions. PVC is a hard, brittle, and inflexible substance, and plasticizers, predominantly diethylhexylphthalate (DEHP), are added to impart flexibility. DEHP is a lipid soluble suspected carcinogen, hepatotoxin, and teratogen which has been shown to leach from PVC products containing lipophilic admixtures. The purpose of this study was to quantitate the amount of DEHP which leaches from PVC bags containing TNS. Six study groups, which contained three formulas stored at 25 degrees C +/- 2 degrees C and 4 degrees C +/- 1 degree C, were assayed for DEHP at time 0, 12, 24, 48 and 72 hr, 1 wk, and 3 wk using high-performance liquid chromatography. The control group contained an amino acid source, a carbohydrate source, and standard electrolytes, and the other groups contained a 10% lipid source or a 20% lipid source in addition to the constituents of the control group. Lipid-containing groups demonstrated detectable levels of DEHP at 48 hr, and DEHP content increased in these groups throughout the 21-day study. DEHP concentrations were lower in lipid-containing groups stored at 4 degrees C than comparable groups stored at 25 degrees C.     

The stability of ascorbic acid in TPN mixtures stored in a multilayered bag

Because of the susceptibility of some vitamins to oxidation, they are not normally added to TPN mixtures until shortly before addministration. Vitamin C (ascorbic acid) is oxidised rapidly, especially in the presence of trace elements. The aim of this study was to investigate the stability of ascorbic acid in complete TPN mixtures in Ultrastab multilayer bags, which are designed to reduce oxygen transmission and thus oxidation, in comparison with standard EVA bags. Ascorbic acid content was determined in two typical TPN mixtures providing 16 g nitrogen, 2000 kilocalories, electrolytes, trace elements and multivitamins, with and without fat emulsion, during storage at 5 degrees C for up to 3 months. In EVA bags ascorbic acid degraded by more than 75% during 24 h and was undetectable in 2-3 days. In contrast, there was a comparatively small initial loss of 15-30% ascorbic acid in mixtures stored in multilayer bags, with little further loss during 1-3 months. Bags containing fat emulsion retained higher concentrations of ascorbic acid after storage compared to those without fat emulsion, but all mixtures in multilayer bags maintained 60-80% ascorbic acid activity after 3 months. Since ascorbic acid is the most oxygen-sensitive vitamin, complete TPN mixtures with vitamins could be compounded in multilayer bags for an extended shelf life, rather than admixing just prior to administration.     

Stability of cocarboxylase in parenteral nutrition mixtures stored in multilayer bags

The aim of this study was to determine the stability of cocarboxylase, a thiamine derivative employed as a vitamin B1 source in multivitamin additives, in parenteral nutrition (PN) mixtures containing different commercial amino acid infusions. In particular, the influence of a metabisulphite-containing amino acid product, Freamine III, was investigated. A liquid chromatographic assay method for cocarboxylase was developed and employed to investigate cocarboxylase degradation during extended storage of PN mixtures at 5 degrees C in multilayered bags. Results indicated that cocarboxylase was relatively stable over the 28-day storage period in PN mixtures containing Synthamin or Vamin products as amino acid source. In contrast, degradation was accelerated in PN mixtures containing Freamine III, suggesting that cocarboxylase is degraded by sodium metabisulphite, showing similar sensitivity to thiamine.     

The photodegradation of vitamins A and E in parenteral nutrition mixtures during infusion

BACKGROUND & AIMS: Vitamins A and E are the most light-sensitive vitamins. Vitamin A is degraded by photolysis, while vitamin E degrades by photo-oxidation. The composition of the parenteral nutrition mixture and the container could therefore influence degradation during daylight administration. The aim of this study was therefore to determine the influence of fat emulsion and the type of bag on the photo-degradation of vitamins A and E in Parenteral Nutrition (PN) mixtures during simulated infusion in daylight. METHODS: Representative adult PN mixtures, with and without fat emulsion, were prepared. Samples for analysis were taken from infusates and each bag during simulated infusion. Degradation of vitamins A and E was determined by stability-indicating HPLC analysis. RESULTS: Results indicated that vitamin A loss proceeded rapidly during infusion, resulting in up to 80% loss in 6 hours, even with light protection of the bag. The presence of fat emulsion did not provide significant light protection. Vitamin E degradation was substantial if mixtures were prepared in EVA bags but was largely prevented if PN mixtures were compounded and stored in multi-layered bags. CONCLUSIONS: It is recommended that all PN bags should be light-protected during infusion in daylight. The use of multi-layered bags will prevent vitamin E losses during infusion.     

Chromium content of total parenteral nutrition solutions

Chromium (Cr) present as contaminant was analyzed by flameless atomic absorption spectrometry in a variety of commercially produced solutions and additives commonly used in total parenteral nutrition (TPN) formulas. Total Cr likely to be administered unintentionally per day was estimated both by summing the Cr in appropriate volumes of each solution required for preparation of standard TPN formulas and by analyzing complete TPN solutions. Storage of TPN solutions in plastic bags for 14 days did not affect Cr concentrations. The amounts ranged from 2.4 to 8.1 micrograms/day for a high glucose formula and 2.6 to 10.5 micrograms for a high lipid formula. Amino acid solutions, especially when containing phosphate, or with phosphate salt additives and with lipid emulsions accounted for approximately 85 to 90% of the Cr found.     

Protecting solutions of parenteral nutrition from peroxidation

BACKGROUND: Light exposure induces the generation of peroxides in solutions of total parenteral nutrition (TPN). Peroxide toxicity has been documented in cell, in tissue, and in isolated organs. To decrease the infused peroxide load and to protect the quality of the parenteral nutrients, we tested the photoprotective properties of different infusion sets. METHODS: Solutions of fat-free TPN and all-in-one total nutrient admixture (TNA) were run through sets of bags (clear and covered) and tubings (clear and colored: black, orange, and yellow) offering different levels of protection against light. Peroxide levels were determined by ferrous oxidation of xylenol orange, thiol functions by the 5,5,-dithiobis(2-nitrobenzoic acid) technique, and absorbance of tubings by spectroscopy. RESULTS: Protection of only the bag had little effect on peroxide generation. In fat-free TPN solutions kept in covered bags, peroxide concentrations were 1.5 to 2 times higher when run through clear compared with colored tubings. When exposed to phototherapy or in the presence of lipids, peroxides were two to three times higher with the clear compared with the black tubing; meanwhile, orange and yellow tubings offered varying levels of protection related to their light-absorbing properties. Colored tubings offered a greater protection against the disappearance of thiol functions. CONCLUSIONS: Covering bags and using orange and yellow tubings may be a practical solution to reduce infused peroxide loads from about 400 to 100 microM. This is especially relevant in patients with an immature or a compromised antioxidant capacity or when phototherapy or preparations of TNA are used.     

Administration of fat emulsions with nutritional mixtures from the 3-liter delivery system in total parenteral nutrition

A series of studies was performed to test the efficacy and safety of a parenteral lipid emulsion, Lipofundin S, when given as part of a complete nutritive mixture from the three-liter bag total parenteral nutrition (TPN) delivery system. In vitro stability studies with mixtures corresponding to high and low nutritional intakes showed the fat emulsion to be stable during refrigerated storage for at least 6 days. The clinical use of Lipofundin S in 3-liter TPN bags was studied in 39 consecutive patients requiring TPN, and there were no untoward side-effects. Nitrogen balance was maintained in patients with pancreatitis, those recovering postoperatively, and those with miscellaneous conditions. However, patients with multiple trauma remained in negative balance. The ability of sera, from patients on TPN to agglutinate Lipofundin S was compared to that from healthy controls, and acutely ill patients not on TPN. Patients on TPN showed a higher degree of in vitro creaming than acutely ill controls, and this may have been related to the severity of the underlying illness. These studies suggest that this parenteral lipid emulsion can be safely administered to patients requiring TPN when given from the 3-liter bag delivery system.     

Impact of Parenteral Lipid Emulsion Components on Cholestatic Liver Disease in Neonates

Total parenteral nutrition (TPN) is a life-saving intervention for infants that are unable to feed by mouth. Infants that remain on TPN for extended periods of time are at risk for the development of liver injury in the form of parenteral nutrition associated cholestasis (PNAC). Current research suggests the lipid component of TPN is a factor in the development of PNAC. Most notably, the fatty acid composition, vitamin E concentration, and presence of phytosterols are believed key mediators of lipid emulsion driven PNAC development. New emulsions comprised of fish oil and medium chain triglycerides show promise for reducing the incidence of PNAC in infants. In this review we will cover the current clinical studies on the benefit of fish oil and medium chain triglyceride containing lipid emulsions on the development of PNAC, the current constituents of lipid emulsions that may modulate the prevalence of PNAC, and potential new supplements to TPN to further reduce the incidence of PNAC.     

Availability of insulin from total parenteral nutrition solutions

Insulin is frequently required in total parenteral nutrition (TPN) solutions to control hyperglycemia. The purpose of this study was to evaluate the recovery of human insulin from standard TPN solutions with and without lipids and from TPN solutions with specialized amino acid formulations and to compare it to the insulin recovery from normal saline. All solutions were mixed in currently utilized PVC-free bags (ethylene vinyl acetate) and drained through PVC-containing tubing. Human insulin (Humulin-R) was spiked with 125I-labeled insulin and then added in concentrations of 10, 25, and 50 units to 1-liter bags containing 39-g amino acids (10% Freamine-III; or 6.9% Freamine HBC; or 8% Hepatamine), 257-g dextrose, electrolytes (Hyperlyte-R), 1000 units of heparin, MVI-12, and MTE-5 Concentrate. Alternate sets of bags contained 125 ml of 20% Intralipid and an appropriate amount of sterile water to keep the final volume at 1 liter. Actual clinical conditions of preparation, storage, and administration were simulated in this in vitro experiment. Multiple samples were collected during the 8-hr infusion period directly in gamma counter vials. All experiments and assays were done in triplicate. Our findings indicate that human insulin availability in TPN solutions is much higher (90%-95%) than the 50% suggested in the literature. Insulin recovery was not appreciably altered by adding lipids or by using Freamine HBC. Insulin recovery from TPN solutions was significantly reduced if they contained Hepatamine (87% and 88%, p less than 0.05) as compared to Freamine (90% and 94%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Answering the fat emulsion contamination question: three in one admixture vs conventional total parenteral nutrition in a clinical setting

Fat emulsions (FE) support microbial growth when inoculated in vitro; dextrose/amino acid solutions (D/AA) do not. Can FE be safely added to D/AA when delivered over 24 hrs? We attempted to answer this question by culturing both conventional (C) total parenteral nutrition (TPN), in which the FE and D/AA are given separately, and the 3-in-1 admixture TPN, in which all components are delivered in one bag. Two-hundred TPN fluid cultures were obtained serially by collecting 1 ml of fluid from the distal-most connection when the TPN was changed every 24 hrs. Quantiative and qualitative cultures were obtained. One hundred sixty-six (83%) were negative. Of the 34 (17%) positive cultures, 15 (17% of 88) were from the conventional system whereas 19 (17% of 112) were from the 3-in-1 system. Six clinically septic patients furnished 11 TPN fluid specimens which grew greater than 400 colonies/ml. Seven (8% of 88) of these were from the conventional system whereas four (3.6% of 112) were from the 3-in-1 system. All had distant sites of sepsis. The 23 remaining positive TPN fluid cultures grew less than 25 colonies/ml, with 20 growing Staphylococcus epidermidis. All of these patients were clinically well and there was no significant difference in the distribution of positive cultures between the conventional system (9%) and the 3-in-1 system (13%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Peroxidation potential of lipid emulsions after compounding in all-in-one solutions

OBJECTIVES: We investigated the peroxidation potential of fat emulsions in all-in-one solutions (AIOs). METHODS: Three 20% emulsions were compared: soybean oil (SO; 60% polyunsaturated fatty acids [PUFAs], alpha-tocopherol:PUFAs = 0.44), soybean plus medium-chain triacylglycerol (SO-MCT; 31% PUFAs, alpha-tocopherol:PUFAs = 0.35), and olive oil (OO; 21% PUFAs, alpha-tocopherol:PUFAs = 1.42). For each emulsion, six AIO solutions were prepared by adding 250 mL of emulsion to a lipid-free solution. Lipid peroxide (LPX) and malondialdehyde (MDA) concentrations were evaluated in fat emulsions, lipid-free solutions, and AIOs immediately (T0) and 24 h (T24) after lipid addition. Statistical analysis was done with analysis of variance. RESULTS: Fat emulsion LPX in SO-MCT was lower than that in SO (P = 0.015) and OO (P = 0.024); LPX in SO was greater than that in OO (P = 0.013); MDA in SO was greater than that in SO-MCT (P = 0.001) and OO (P = 0.013); and MDA in SO-MCT was greater than that in OO (P = 0.001). In comparison with MDA at AIO-T0, MDA at AIO-T24 increased in SO (P = 0.005) and SO-MCT (P < 0.001) and decreased in OO (P = 0.003); at AIO-T24, LPX was greater in SO, but not significantly. CONCLUSIONS: In AIO bags, LPX occurred within 24 h after the addition of the lipid emulsion and seemed to be directly related to the PUFA content and inversely related to the alpha-tocopherol:PUFA ratio of the emulsion.     

Plasma and red blood cell vitamin E status of patients on total parenteral nutrition

Plasma and red blood cell (RBC) tocopherol isomer (alpha, beta, delta, and gamma) concentrations were measured prior to, and following total parenteral nutrition (TPN), with Intralipid. Before feeding, nine of 13 patients had plasma total tocopherol levels less than 0.6 mg/dl (normal range 0.63-1.24 mg/dl) and 10 of 13 had total RBC tocopherol levels less than 0.2 mg/dl (normal range (0.20-0.39 mg/dl). Following 7 days TPN plasma vitamin E status increased significantly (p less than 0.001). However, this was due mostly to increases in the circulating level of beta + gamma-tocopherols. RBC vitamin E status was also significantly increased (p less than 0.001) following TPN, however, this was again due to incorporation of non-alpha-tocopherols. In a second study a alpha-tocopherol supplement, Vitlipid N, (9.1 mg alpha-tocopherol/day) was included in the feed. In these patients, large increases in plasma concentrations of non-alpha-tocopherol isomers were accompanied by an apparent improvement in alpha-tocopherol status (0.64 vs 0.44 mg/dl after 7 days). However, RBC alpha-tocopherol concentration did not change appreciably in these patients following either 7 or 14 days feeding. It is concluded that RBC vitamin E status is markedly influenced by the available plasma tocopherol pool and that provision of a small supplement of alpha-tocopherol is not sufficient to compete with the high concentration of non-alpha-isomers present in Intralipid. TPN utilizing fat emulsions containing high levels of non-alpha-tocopherol isomers (even when accompanied by alpha-tocopherol supplements) does not improve alpha-tocopherol status.     

Lipid peroxidation of intravenous lipid emulsions and all-in-one admixtures in total parenteral nutrition bags: the influence of trace elements

An iodometric titration was used to assess the influence of a daily portion of trace elements on lipid peroxidation of pure lipid emulsions and lipid-containing all-in-one (AIO) admixtures by measuring the peroxide value (PV; mmol peroxides/L). A pure lipid emulsion (Intralipid 20%; Pharmacia & Upjohn, Dubendorf, Switzerland) was stored in ethylvinylacetate bags under light protection (LP) at 40 degrees C with and without trace elements. In absence of trace elements the PV of Intralipid 20% was significantly lower (day 14: 2.77 vs 18.04; p < .001). After the same time period with the same storage conditions the drop in pH was two times higher in presence of trace elements (1.54 vs 0.77). In an AIO admixture with LP stored at 2 degrees C to 8 degrees C, trace elements increased the PV from 0.04 to 0.19 mmol/L (day 29; p < .01). The drop in pH was 0.01 and 0.02 units, respectively. When stored at 20 degrees C to 30 degrees C and exposed to daylight, the PV of the AIO admixture containing trace elements reached 1.92 compared with 0.52 in their absence (day 19; p < .001) with a pH drop of 0.03 and 0.11, respectively (day 29). Although trace elements led to a much higher drop in pH in pure lipid emulsions, no obvious influence on the pH of AIO admixtures was demonstrated. To minimize lipid peroxidation, AIO admixtures should be stored light-protected and refrigerated without trace elements. The latter should be added immediately before administration or should be given separately.     

Insulin adsorption to three-liter ethylen vinyl acetate bags during 24-hour infusion

Insulin adsorption to ethylen vinyl acetate, 3-liter bags injected with 10 insulin units, during 24-hr infusion has been studied. Three different infusions systems (A, B, and C) were tested and eight bags for each system were used. An elevated insulin adsorption resulted in each system. The maximal insulin recovery, expressed as percentage of the original theoretical 3333 microIU/ml insulin concentration, was 19.54% (at time 6), 20.93% (at time 4), and 16.95% (at time 22) for system A, B, and C, respectively. "Dismissed insulin amount" after 24-hr infusion was 1590 +/- 279.5 microIU, 1505.8 +/- 430.5 microIU, and 1253.3 +/- 369.8 microIU for system A, B, and C, respectively. Comparison of insulin concentration values at different times revealed significant differences only at time 18 (if compared with times 0,2.4,6,8,12,14,16) ant at time 20 (if compared with time 4,6,8,10) for system A, and at time 4 (if compared with time 12,14,16,18,20,22,24) for system B. We conclude that a constant but low insulin delivery can be achieved using 3-liter EVA systems and a 24-hr infusion.