Parenteral and Enteral Nutrition

Transcription

1 Parenteral and Enteral Nutrition Audis Bethea, Pharm.D. Assistant Professor Therapeutics I December 5 & 9, 2003 Parenteral Nutrition Definition process of supplying nutrients via the intravenous route Synonyms I. total parenteral nutrition (TPN), peripheral parenteral nutrition (PPN) Indications I. NPO for 5 7 days II. Patients who cannot or will not receive nutrition by the enteral/oral route for 5-7 days

2 Parenteral Nutrition Route of administration PPN peripheral venous access I. Small, low flow vessels II. Limited to low osmolar solutions III. High incidence of extravasation TPN central venous access I. Large, high flow vessels II. Less incidence of extravasation Parenteral Nutrition Osmolarity limits Peripheral mosm/l Central 1800 mosm/l I. Increased osmolarity limits allows for increased concentrations of dextrose and amino acids to be delivered Osmolarity of additives (per 1% final concentration) Amino acids 100 mosm/l Dextrose 50 mosm/l Lipids 1.7 mosm/l Electrolytes mosm/meq

3 Parenteral Nutrition Modes of delivery I. 2 in 1 (Dextrose, AA, electrolytes) with fat emulsion administered separately II. 3 in 1 all parenteral nutrients in one bag Parenteral Nutrition Route of administration PPN peripheral venous access I. Small, low flow vessels II. Limited to low osmolar solutions due to high incidence of thrombophlebitis and extravasation TPN central venous access I. Large, high flow vessels such as inferior, superior vena cava, internal jugular (vessels close to the heart) II. Less incidence of thrombophlebitis and extravasation with high osmolar solutions

4 Parenteral Nutrition 3 in 1 all parenteral nutrients in one bag Advantages I. Decreased infection rate due to less venous line manipulation II. Fewer intravenous lines required for administration III. Decreased preparation time IV. Ease of administration for home use V. Better delivery of fat soluble vitamins VI. Decreased incidence of bacterial growth in preparation Disadvantages I. Lipids may occlude central venous catheters II. Addition of lipids creates compatibility concerns III. Stability of the solution is decreased by the addition of lipids IV. Addition of lipids impairs visual inspection of precipitates Designing Parenteral Nutrition Carbohydrates (CHO) Dextrose monohydrate primary energy source (3.4 kcal/g) Stock (manufactured) concentrations of dextrose range from 5-70% I. Dextrose 70% (D70W) most commonly used to prepare PN solutions Amount of CHO in a PN solution is dependant upon I. Caloric requirements II. Optimal balance of CHO and fat for non-protein calories (NPCs)

5 Designing Parenteral Nutrition Amino acids (AA) Highest source of energy in PN solutions (4 kcal/g) **NOT USED AS A ENERGY SOURCE** Standard solutions provide essential, semi-essential, and non-essential AA I. Essential AA unable to be produced by your body; must be ingested from diet II. Semi-essential body cannot produce in stressed states III. Non-essential AA can be produced with adequate nutritional intake Specialty formulas are available for patients with renal and hepatic dysfunction AA solutions have high osmolarity which limits there use in PPN solutions Designing Parenteral Nutrition Intravenous fat emulsions (Lipids) Concentrated source of calories I. 10% solution provides 1 kcal/ml II. 20% solutions provides 2 kcal/ml Provide essential fatty acids (Linoleic and linolenic acid) I. < 10% of daily caloric intake consisting of lipids may lead to depletion of essential fatty acids Optimal lipid intake/supplementation is 20-40% of total daily calories Lipids infused via PPN may provide protection from phlebitis

6 Practice Calculation You are now ready to order a TPN that will provide your patient with 2600 kcal/day, 150 g of protein/day, and 2500 ml/day. You have decided to decrease the fluid supplementation provided via TPN to account for the extra fluids the patient is receiving through other IV medications. Your hospital only prepares 3-in-1 TPNs so you will need to prepare an order that includes the % of dextrose, protein, and the amount of lipids that you need to provide. 1. Determine what NPC:N ratio you would like to use. Stressed patient :1 = 150 g protein / 6.25 = 24 g N = 2600 kcal / 24 g N = kcal (NPC):N 2. You decide to provide the NPC as 70% CHO and 30% lipids. How many calories will now be given in the form of CHO and fat? CHO = 2600 kcal (0.7) = 1820 kcal Lipids = = 780 kcal (rounded to 750 ml) Practice Calculation Now you need to determine the percentages of dextrose, protein, and the amount of lipids (ml) you need to put into the TPN to provide the calculated parameters. 1. % Dextrose **Hint = % means # of grams per 100mL** **This TPN will provide 25, 100s (2500/100 = 25)** = 1820 kcal 3.4 kcal/g = g CHO = g CHO 25 = 21% (round to D 20%) 2. % AA = 150 g AA 25 = 6% AA 3. Lipids **Ordered as # of calories or ml** ***Can use 10 or 20% lipids*** 10% (1 kcal/ml) = 750mL or 20% (2 kcal/ml) = 375 ml

7 Designing Parenteral Nutrition Electrolytes Electrolyte supplementation is tailored to individual patient requirements Supplementation may be affected by sensible losses and complications of illness (diarrhea, ostomy drainage, diaphoresis, refeeding, etc.) Chloride vs. acetate intake is depends on acid-base balance I. Generally use equal amounts to maintain balance (1:1 ratio) a. Metabolic acidosis maximize acetate b. Metabolic alkalosis maximize chloride Calcium and phosphorus are conditionally incompatible!! Designing Parenteral Nutrition Intravenous vitamins Designed to provide daily allowances Disease states may alter vitamin requirements Intravenous trace elements Designed to provide daily allowances Standard preparations contain Mn, Cu, Zn, and Se Insulin Added to PN solution to prevent hyperglycemia induced by high (CHO) load Up to 10% of insulin added to PN solution may adsorb to the IV bag I. Advantages a. Tight control of blood glucose improves outcomes and reduces infection b. Prevents consumption of protein as energy source

8 Practice Calculation CW s TPN order for D20% w/ 6% AA and 375mL 20% lipids is nearing completion. Based on the following basic metabolic panel finalize the order by adding the necessary electrolyte supplementation. CW has been receiving IVF of ½ NS (77meq NaCl / L)w/ 20 meq 75mL/hr. ***IVF have provided 1800mL of fluid/d, 36 meq of KCl, and meq of NaCl Sodium 130 meq/l ( ) Potassium 3.2 meq/l ( ) Chloride 96 meq/l ( ) Bicarbonate 35 meq/l (21-31) Glucose 130 mg/dl (60-110) BUN 20 mg/dl (5-18) Creatinine 0.9 mg/dl ( ) **As ordered in the TPN** Sodium 100 meq/l Potassium 25 meq/l Chloride:Acetate ratio 2:1 Add MVI, trace elements **Remember Ca-Phos product for precipitation** Consider adding insulin if BG increases Practice Calculation CW s TPN has been is now being infused. You are ready to go home for the day, but need to first order labs for monitoring CW s TPN. What do you order? 1. Daily BMP w/ Ca, Phos, Mg, CBC, FSBG, physical exam, intake/output 2. Weekly PREALBUMIN, LFTs, trace elements +/- transferrin, +/- indirect calorimetry

9 Complications of Parenteral Nutrition Gastrointestinal atrophy Infection Hyperglycemia Venous extravasation Enteral Nutrition IF THE GUT WORKS USE IT!! Advantages over parenteral nutrition Avoids risks of phlebitis and infection associated with intravenous catheters More physiologic due to stimulation of GI tract Preserves the integrity of intestinal lining and enzymatic activity I. GI tract provides means to extract nutrients II. Reduces risk of infection via translocation of bacteria from GI tract III. Maintains normal functioning of biliary system Less costly Contraindications to enteral nutrition Malabsorptive disorder Severe gastrointestinal diseases

10 Enteral Nutrition Administration of enteral nutrition Oral Feeding tubes NG / OG / NJ PEG / PEJ Enteral Nutrition Choosing a feeding tube Stomach I. Most physiologic II. Sensation of being full III. Allows use of numerous feeding formulas IV. Must have intact gag reflex Intestine I. Patients with gastroparesis II. Delayed gastric emptying III. High risk of aspiration

11 Enteral Nutrition Administration technique Bolus I. More physiologic II. Not administered via tubes in duodenum or jejunum III. Administer < 400 ml per bolus Continuous I. High nutritional requirements II. Tubes in the duodenum or jejunum Classification of Enteral Formulas Monomeric formulas (Peptamen, Vivonex ) Pre-digested amino acids to improve absorption Recommended for patients with altered GI function I. Peptide-based partially digested (Peptamen ) II. Elemental most pre-digested form with proteins as free AA Polymeric formulas (Osmolite, Complete modified, IsoSource ) Contains intact macronutrients triglycerides, protein, and CHO polymers Highly concentrated and fiber enhanced feeding formulas Formulas require normally functioning GI tract and absorptive capacity

12 Classification of Enteral Formulas Specialized, disease specific formulas (Pulmocare, Nutrihep ) Modified for pulmonary, renal, hepatic, and endocrine failure Composition and nutrients vary with indication (modified to a specific disorder) Allows maintenance of nitrogen balance without exacerbating underlying disease Specialized formulas are extremely expensive Feeding modules/caloric additives CHO (carbohydrate polymers) Moducal, Polycose Protein (casein, whey) ProMod, Casec Fat MCT oil, Microlipid, corn oil Fiber Unifiber Characteristics of Enteral Formulas Osmolality osmolality may decrease gastric emptying leading to diarrhea and dehydration Estimated free water Usually dependent upon the formula s concentration I. < 1.5 kcal/ml 80% free water II. > 1.5 kcal/ml 70% free water Percentages account for the amount of water available to meet daily fluid requirements after the product is absorbed Fiber content Fiber supplementation may help to maintain normal bowel function

13 Administration of Enteral Nutrition Intermittent (bolus) administration Nutritional supplementation administered as 4-8 boluses Simulates normal physiologic eating patterns Less likely to promote drug-food interactions Higher risk of aspiration Continuous administration Beneficial in patients with high nutritional requirements Useful in patients with malabsorption due to rapid GI transit or impaired digestion Lower risk of aspiration More likely to promote drug-food interactions Administration of Enteral Nutrition Residuals Amount of enteral formula and GI secretions left in the stomach or intestine High residuals I. Poor gastric or intestinal transit/emptying II. Increased risk for aspiration III. Hold feeds a. Bolus feeding > 100mL b. Continuous feeding > 1/2 of rate administered Therapy for high residuals I. Hold enteral feedings II. Initiate drug therapy with promotility agents a. Metaclopramide b. Erythromycin

14 Practice Calculation The physician thanks you for your excellent work in providing nutritional support for CW (prealbumin is 29 mg/dl). In fact CW is doing so well that we are ready to transition him from parenteral to enteral nutrition. The surgeons would prefer to feed CW via nasogastric tube to prevent introduction of a foreign body into his resected intestine. Please prepare a EN regimen for CW that includes parameters for transitioning from PN. **You have decided to use a concentrated formula (1.5 kcal/ml) in order to meet CW s caloric needs. 1. How many ml of formula will CW require? 2100 ml (to provide 3200 kcal) this formula will provide ml of water 2. Bolus vs. continuous administration? Bolus goal rate of 350 ml q4 hours Practice Calculation Please provide parameters for transitioning CW from TPN to EN and identify any monitoring parameters that may be different from those used with TPN. 1. Initiate EN at 50 ml q4 hours and increase bolus by 50 ml with every feed to a goal rate of 350 ml. Flush tube with 150 ml water q4 hours 2. Decrease TPN to 1 liter and discontinue tomorrow if patient is at EN goal. 3. Monitor residuals q4 x three boluses. Hold boluses and initiate promotility agent residuals are greater than > 100mL 4. Monitor tube placement every shift

15 Nutritional Supplementation