Lecture 10b 18 March 2013 Parenteral Feeding

Parenteral Feeding (going around ie circumventing the intestine) Nutrients go directly into blood stream bypassing gastrointestinal tract-this is done by intravenous needle or catheter Used when a patient cannot, due to physical or psychological impairment, consume sufficient nutrients enterally Used when patients gi system will not adequately process food for body Actual infusion depends on site of infusion and patient’s fluid and nutrient requirements

Types of Parenteral Nutrition Peripheral parenteral nutrition (PPN)- peripheral vein used Total parenteral nutrition (TPN)-superior vena cava used Basic difference between the two is the concentration of nutrients infused (higher concentration is used for TPN due to more rapid dilution in superior vena cava)

Parenteral Feeding Usual fluid volume is L over a 24 hour period for most people

Parenteral Feeding Composition of ingredients in bag for intravenous Delivery Dextrose Amino acids Lipid emulsion Sterile water Electrolytes Vitamins

Carbohydrate Dextrose- provides 3.4 kcal/g and not 4 kcal/g -difference is due to what? Concentration is 12.5 % (max for peripheral introduction) to 25 % (total parenteral nutrition) Restricted in ventilator patients because oxidation of glucose produces more carbon dioxide than does oxidation of fat

Protein Mixture of essential and non-essential amino acids Concentration % Quantity of amino acids depends on patients estimated requirements and hepatic and renal function-why?

Lipid emulsions Safflower and soybean oil with egg lecithin used as an emulsifier (why the emulsifier and how does it work?) Isotonic Significant source of calories

Lipid emulsions Available in 10, 20, 30 % concentrations supplying 0.9 and 1.8 and 2.7 kcal/ml respectively-Do the math Usual dose is 0.5 to 1 g/kg/day to supply % of total kcal requirement IV fat contradicted for severe hepatic pathology, hyperlipidemia or severe egg allergies Used cautiously with atherosclerosis, blood coagulation disorders

Electrolytes Dictated by patients blood chemistry values and physical assessment findings

Standard multivitamin and trace mineral preparations added to parenteral solutions to meet micronutrient needs

PPN -must be isotonic and therefore low in dextrose and amino acids to prevent phlebitis and increased risk of thrombus formation The need to maintain isotonic solutions of dextrose and amino acids while avoiding fluid overload limits the caloric and nutritional value of PPN

PPN delivers complete but limited nutrition the final concentration cannot exceed 12.5 % dextrose-lower concentrations of amino acids vitamins and minerals are added lipid emulsion may be added to supplement calories depending on the patients tolerance

PPN -provides temporary nutritional support -short term days and do not require more than 2000 to 2500 kcal per day

PPN -may be used for a post surgical ileus or anastomotic leak or for patients who require nutritional support but are unable to use TPN because of limited accessibility to a central vein -sometimes used to supplement an oral diet or tube feeding or transition from TPN to enteral intake

TPN Hypertonic solutions provide more dextrose and/or protein but they must be delivered centrally in a large diameter vein so that they can be quickly diluted

TPN TPN is used when nutritional requirements are high and anticipated need is relatively long 3 litres of 10 % dextrose provides only 1020 kcal -calculation

TPN -traditionally-catheter to superior vena cava figure 21-2

TPN Indications severe malnutrition GI abnormalities : due to obstruction, peritonitis, severe acute pancreatitis after surgery or trauma especially that involving extensive burns, sepsis need for supplementation of inadequate oral uptake in patients who are being treated aggressively for cancer bone marrow transplantation

TPN cyclic -constant infusion for 8-12 hours -used for home patients -used to support inadequate oral intake -allows insulin and glucose to drop when infusion is not taking place -switch from continuous TPN to cyclic TPN should be gradually decreased by several hours per day and signs of glucose overload and fluid imbalance should be monitored