Micronutrients

To provide complete nutritional support, micronu-trients, electrolytes, and minerals also need to be in the parenteral solution. The addition of adequate amounts of calcium and phosphate in one solution may be particularly problematic since precipitation may occur. Solubility guidelines are available that account for the brand and percentage of amino acids, which impact the pH of the solution. Compounding guidelines for the order of addition of calcium and phosphorus, amounts of other additives, and the temperature of the solution are other factors to optimize the solubility. Filters in the delivery system also help to minimize the risk of occlusion of the catheter if a solution should precipitate, especially with trimix solutions, in which lipids are mixed with the glucose/amino acid solution. Studies have evaluated the stability of the variety of nutrient components in trimix solutions.

Before the availability of vitamins and minerals, plasma levels of micronutrients decreased rapidly while infusing only macronutrients. The only commercial preparation initially available was a trace element solution that had iron and iodide. The first commercial preparation of multivitamins for intravenous use, introduced in the 1960s, lacked folic acid, vitamins B12 and K, and biotin. It also had very high concentrations of vitamins A and D and thiamin. Because of the variability in practice, there was increased risk of toxicity to vitamins A and D and deficiencies of other vitamins. Recommendations were made for intravenous pediatric and adult intravenous preparations in 1975. By 1978, there was a commercial multivitamin preparation that met these recommendations. Current preparations contain all vitamins for which there are Dietary Reference Intake values, with the exception of choline. A recent Food and Drug Administration mandate requires the addition of vitamin K to all preparations. Differences between the pediatric and adult forms of MVI include amounts of B vitamins and vitamin D (Table 3). There is currently no multivitamin preparation specifically for the premature infant. Dosing recommendations of Pediatric MVI for this group are based on weight (one-third vial for <500 g, two-thirds vial for 500-1000 g, and full vial for more than 1000 g).

A few trace element deficiencies have been noted in patients receiving long-term PN support. The first case of chromium depletion was reported in 1977, that of selenium deficiency in 1979, and that of molybdenum in 1981. There are now many trace element solutions available with a variety of combinations of minerals and that are appropriate to meet the needs of premature infants through the adult population. They are also available as single elements to tailor a solution as

Table 3 Comparison of parenteral multivitamin preparations for pediatric and adult populations

Vitamin MVI Pediatric Infuvite (Baxter) and

(Mayne) MVI Adult with vitamin K (Mayne)

Table 3 Comparison of parenteral multivitamin preparations for pediatric and adult populations

Vitamin MVI Pediatric Infuvite (Baxter) and

(Mayne) MVI Adult with vitamin K (Mayne)

A (IU)

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