Enteral nutrition  • the delivery of nutrients in liquid form directly into

the stomach, duodenum, or jejunum.

Parenteral nutrition  • administration of nutriment intravenously.• nutrition which is delivered through a system other than the digestive system.

Total Parenteral Nutrition  (TPN) • intravenous administration (via a central venous

catheter) of the total nutrient requirements of a patient with gastrointestinal dysfunction.

Total Parenteral Nutrition Also called central parenteral nutrition (CPN) or

‘hyperal’ (hyperalimentation). [The term ‘hyperalimentation’ is a misnomer because it

incorrectly implies that nutrients are supplied in excess of needs].

Large amounts of nutrients in a hypertonic solution can be supplied via TPN. The catheter is surgically placed into the superior vena cava.

The reason that larger amounts of nutrients in a hypertonic solution can be supplied via the superior vena cava than with peripheral parenteral nutrition is that the superior vena cava has a much larger diameter and a higher blood flow rate, both of which quickly dilute the TPN solution.

Definition Total parenteral nutrition (TPN) is a way of

supplying all the nutritional needs of the body by bypassing the digestive system and dripping nutrient solution/s directly into a vein.

The administration of a nutritionally adequate hypertonic solution (consisting of glucose, protein hydrolysates, minerals, and vitamins) through an indwelling catheter into the superior vena cava or other main vein.

Normally TPN is administered in a hospital, but under certain conditions and with proper patient and caregiver education, it may also be used at home for long-term therapy (HPA).

Ideally, TPN provides all the nutrients in the correct quantities to ensure the body functions normally.

Types of PN 2 types of IV (or parenteral) nutrition.

Partial parenteral nutrition (PPN) : - given for short periods of time, - to replace some of the nutrients required daily and only supplements a normal diet.

Total parenteral nutrition (TPN) : - given to patients who can’t eat anything and must receive all nutrients required daily through an intravenous line.

Home parenteral nutrition (HPN) : usually requires a CVC (central venous catheter), which must first be inserted in a fully equipped medical facility. After it is inserted, therapy can continue at home.

Parenteral nutrition is administered outside the digestive tract, intravenously.

Enteral nutrition encompasses oral and tube feedings into the digestive tract.

General rule : ‘if the gut works, use it’. The GI tract should be used if possible because it tends

to atrophy when not used. Gut bacteria can translocate to the circulatory system through an atrophied GI tract and increase the risk of infection.

Peripheral parenteral nutrition (PPN) or Peripheral venous nutrition (PVN) nutrients are supplied via a peripheral vein, usually a

vein in the arm.

PPN feedings usually supplement enteral feedings. Large amounts of nutrients cannot be supplied via a

peripheral vein, because these relatively small veins cannot tolerate the rush of fluid into the vein that occurs when a hypertonic solution is introduced into the circulatory system.

Body fluids have an osmolarity of about 300 mOsm. The introduction of a hypertonic solution into a body compartment will cause an osmotic gradient, resulting in a fluid shift.

WHAT HAPPENS ? When a hypertonic solution is introduced into a small

vein with a low blood flow, fluid from the surrounding tissue moves into the vein due to osmosis. The area can become inflamed, and thrombosis can occur.

Osmolarity of Solutions Proteins and carbohydrates both contribute to

hypertonicity. Fat being isotonic, can be administered peripherally.

However, if the patient has delayed lipid clearance, the use of lipids is contraindicated.

Infusion of Peripheral Nutrition The catheter is inserted into the arm vein of the

patient. Up to 1800-2500 kcal and 90g protein can be supplied

via PPN. This relatively high kcalorie/protein amount can be

supported peripherally only for a short period of time.

Recommended Rates

IBW (kg)

Infusion rate (cc/hr)

40 60 - 8050 75 - 10060 90 - 12070 100 - 14080 120 - 16090 130 - 170

Purposes Used when individuals cannot or should not get

their nutrition through eating. Used when the intestines are obstructed, when the

small intestine does not absorb nutrients properly, or a GI fistula (abnormal connection) is present.

To ensure ‘Bowel rest’ (food does not pass through the bowels).

[Bowel rest may be necessary in Crohn's disease,

pancreatitis, ulcerative colitis, and with prolonged bouts of diarrhea in young children].

Purposes (contd’)

Used for individuals with severe burns, multiple fractures, and in malnourished individuals to prepare them for major surgery, chemotherapy, or radiation therapy.

Individuals with AIDS or widespread infection (sepsis) may also benefit from TPN.

To rehydrate a patient post-viral illness. Patients with more serious and long term illnesses

and conditions may require months or even years of intravenous therapy to meet their nutritional needs. These patients may require a central venous access port.

A specialized catheter (Silastic Broviac or Hickman) is inserted beneath the skin and positioned below the collarbone. Fluids can then be injected directly into the bloodstream for long periods of time. X- rays are taken to ensure that the permanent catheter is properly positioned.

Description The hyperalimentation solution is infused through

conventional tubing with an IV filter attached to remove any contaminates.

In adults, the catheter is placed directly into the subclavian vein and threaded through the right innominate vein into the superior vena cava.

In infants and small children the catheter is usually threaded to the central venous location by way of the jugular vein (which is entered through a subcutaneous tunnel beneath the scalp). Sometimes, the umbilical vein is used.

Strict asepsis must be maintained because infection (sepsis and septicaemia) is the primary risk.

Once the catheter is in place, a CXR is done to make sure the placement is correct.

TPN solution is mixed daily under sterile conditions.

Description (contd’)

Maintaining sterility is essential for preventing infection.

- The outside tubing leading from the bag of solution to the catheter must be changed daily. - The special dressings covering the catheter must be changed every other day.

Contents of the TPN solution

Are determined / individualized, based on the individual variables (age, weight, height, and the medical condition/s) .

All solutions contain - sugar (dextrose) for energy - proteins (AA) - fats (lipids) - electrolytes (K+, Na+, Ca+, Mg+, Cl- and phosphate); these are essential for normal body functioning. - trace elements (Zn, Cu, Mn and Cr) - vitamins - insulin (helps the body use sugar), may need to be added.

The TPN catheter is used only for nutrients; medications are not added to the solution.

Contents of the TPN solution (contd.)

For Adults: approx. 2 lts of TPN solution daily (varies with the individual’s age, size and health).

The solution should be allowed to be warmed to room temperature before intravenous nutrition begins. The solution is infused slowly at first to prevent fluid imbalances, then the rate is gradually increased. The infusion process takes several hours.

Successful TPN requires frequent, often daily monitoring of the individual's parameters [weight, glucose levels, FBC, blood gasses, fluid balance, urine output, waste products in the blood (plasma urea); electrolytes];

LFT & RFT may also be performed (special cases).

Conventional IV solutions are…. - sterile water with small amounts of sodium (salt) or

dextrose (sugar) supplied in bottles or thick plastic bags that can hang on a stand mounted next to the patient's bed.

- Additional minerals, vitamins, or drugs can be added to the IV solution by injecting them into the bottle or bag with a needle.

- These simple sugar and salt solutions can provide fluids, calories, and electrolytes necessary for short periods of time.

- If a patient requires IV feeding for more than a few days, additional nutrients like proteins and fats will be included. The amounts of each of the nutrients to be added will depend on the patient's age, medical condition, and particular nutritional requirements.

3-in-1 solution : glucose, proteins and lipids

Infusion: Medical Infusion pump: - preferred method (sterile bag of nutrient solution + pump) - pump infuses a small amount (0.1 to 10 mL/hr) continuously in order to keep the vein open. - feeding schedules vary, but normally the regimen ramps up the nutrition over one hour, levels off the rate for a few hours, and then ramps it down over a final hour (in order to simulate a normal metabolic response resembling meal time). This should be done over 12 to 24 hours rather than intermittently during the day. Chronic PN is performed through a central IV catheter,

usually through the subclavian or jugular vein with the tip of the catheter at the superior vena cava without entering the right atrium.

PICC line : - Peripherally Inserted Central Catheter - originates in the arm, and extends to one of the central veins (such as the subclavian with the tip in the superior vena cava).

Preparation Preparation to insert the catheter involves creating a sterile

environment. Other special preparations are not normally necessary.

Aftercare During the time the catheter is in place, patients and caregivers

must be alert to any signs of infection (redness, swelling, fever, drainage or pain).

Risks TPN requires close monitoring. Two types of complications can develop as a result of inserting

the catheter into a vein … * Pneumothorax (infection, air in the lung cavities) * Thrombosis (blood clot formation) subsequent to phlebitis. Metabolic and fluid imbalances * occur if the contents of the nutritional fluid are not properly balanced and monitored. * Hypoglycemia – most common metabolic imbalance; caused by abruptly discontinuing a solution high in sugar.

Risks (contd.)

If the needle becomes dislodged, it is possible that the solution may flow into tissues around the injection site rather than into the vein.

NUTRITIONAL COMPONENTS Amino Acid (AA) Solutions

Protein is provided as a crystalline amino acid solution. 500 ml bottles are standard. Solutions vary in amino acid concentration and

composition. The patient's protein needs determine the protein

concentration to use. The underlying disease state/s determines the

composition of amino acids to use.

Amino Acid Solutions/Concentrations  Amino acid (AA) solutions are generally available in the

following concentrations:

Percent Solution (%)

AA Content (g/100 mL)

3.0 3.0

3.5 3.5

5.0 5.0

7.0 7.0

8.5 8.5

10 10

Uses of Amino Acids AAs do not normally contribute to the kcalorie

requirement of the patient (although they have 4 kcals per gram).

Instead of being used for energy, amino acids should be used for protein synthesis.

To determine protein needs, a nonprotein kcalorie to nitrogen ratio of 80:1 to 150:1 is used.

Nonprotein kcal:N ratio • 80:1 the most severely stressed patients• 100:1 severely stressed patients• 150:1 unstressed patient

Dextrose Solutions

Dextrose in solution has 3.4 kcals/gram (rather than 4 kcals/gram as in dietary carbohydrates), because a noncaloric water molecule is attached to dextrose molecules.

Dextrose solutions come in different concentrations, and the solution is abbreviated D(%solution)W.

Eg.: D50W indicates a 50% dextrose in water solution.

Dextrose Solution ConcentrationsDextrose solutions are available in the following

concentrations:

Percent soln. (%)

Dextrose (g/100 ml)

Notation

5 5 D5W10 10 D10W20 20 D20W30 30 D30W40 40 D40W50 50 D50W60 60 D60W70 70 D70W

Infusion Rate of Dextrose Dextrose solutions should NOT be administered at a

rate higher than 0.36g per kg body weight/hour. This is the maximum oxidation rate of glucose. Excess glucose is converted to fat (which can result in

fatty liver). The conversion of carbohydrate to fat can cause excess

CO2 production (which is undesirable for patients with respiratory problems).

Calculation Example :For 60 kgs patient,

0.36 x 60 kg x 24 hr = 518 grams per day

(Dextrose infusion should not be greater than 0.36g/kg/hr).

Calculate the maximum dextrose tolerance for the following weights

Weight (kgs)70 8090

100

LIPID EMULSIONS Lipids in PN are used as a source of essential fatty acids

(EFA) and energy. Lipid emulsions are composed of soybean and/or

safflower oil, glycerol, and egg phospholipid. Approx. 4% of total kcaloric intake should be EFAs to

prevent EFA deficiency. IV lipids are a good source of kcalories for

hypermetabolic patients, or patients with volume or carbohydrate restrictions (as they are isotonic and calorically dense).

Lipids can provide upto 60% of non-protein calories. Usually composed of long chain triglycerides (LCT). In some cases, LCT + medium chain triglycerides (MCT)

may be beneficial.

F.Y.I.Before lipids could be administered intravenously, EFAs were provided by rubbing vegetable oil into the patient's skin. However, the efficacy of this procedure is controversial, but it might be used in the case of patients who cannot tolerate a lipid emulsion.

Lipid Emulsion Concentrations IV lipids come in concentrations of 10% or 20%

emulsions. The 10% emulsion contains 1.1 kcal/ml. The 20% emulsion contains 2 kcal/ml. Bottles come in 100 ml, 200 ml, 250 ml and 500 ml

volumes. 500 ml of 10% lipids given once or twice a week is

generally enough to prevent EFAs deficiency. The lipid emulsion does not have to be mixed with the

AA and dextrose solutions in a single bag.

LIPID EMULSION ADMINISTRATION Lipid emulsions are not provided continuously (to

prevent hyperlipidemia). This gives the body a chance to clear lipids from the blood.

Usually, lipids are administered 1-2 times per week, but can be provided daily, under stringent monitoring.

Recommended infusion times are 4-6 hours for 10% lipids and 8-12 hours for 20% lipids.

12-24 hour infusions may be better tolerated by some patients.

A total of 2.5g lipids /kg per day should not be exceeded.

Calculation example of maximum daily lipids

For a 60 kg patient, 2.5g x 60 kg = 150g lipid per day maximum

Calculate maximum lipid tolerance for the following weights:

Weight (kgs)70 8090

100

Evaluation of Lipid ToleranceThere are three methods that can be used for evaluation of a patient's lipid tolerance:

Test Dose Serum Triglycerides

Plasma Turbidity

Test Dose Method

10% lipid infused @ 1ml/min for 15-30 min; if no adverse symptoms, the rate can be increased to

80 - 100 ml/h

OR

20% lipid emulsion infused @ 0.5 ml/min for 15 – 30 min; if no adverse symptoms, the rate can be

increased to 40 - 50 ml/h

Serum Triglyceride Method Determine a baseline serum triglyceride level before

the emulsion is administered. Determine the triglyceride level 8 hours after the

infusion has been terminated. If serum triglycerides are normal or if they exceed

250 mg/day, lipids should be given at a reduced rate or should be used only to prevent EFAs deficiency.

Plasma Turbidity Method Plasma is observed for turbidity. If turbidity is present, the lipid infusion must be

adjusted. Not the best method for testing lipid tolerance,

because hyperlipidemia can occur without turbidity.

Contraindications for Lipid Emulsions Abnormal lipid metabolism Lipid nephrosis Acute pancreatitis (if concomitant with or caused by

hyperlipidemia) Severe egg allergies

Use lipid emulsions with caution if the patient has: A blood coagulation disorder Moderate to severe liver disease Compromised pulmonary function

Administration of Lipids Lipids are administered in a bottle that is ‘Y-connected’

(‘piggybacked’) to the IV line containing AA/dextrose mixture.

Total nutrient admixtures (TNAs) also called ‘3-in-1 systems’, allow for lipids to be administered with AAs and dextrose.

Mineral Increase Needs Decrease Needs

Potassium

Potassium wasting meds DiuresisAnabolism GI losses (vomiting, diarrhea, suction)

Potassium sparing meds Renal failure Massive tissue destruction

Sodium Diuretic use GI losses (above)

Hepatic failure Congestive heart failure

Calcium Pregnancy Pancreatitis

•Hypercalcemia

Phosphorus Anabolism Renal failure

Chloride Metabolic alkalosisNasogastric suction

•Metabolic acidosis

Magnesium

Anabolism Mg wasting meds Hypokalemia Alcoholism GI losses (short bowel syndrome, diarrhea, intestinal fistula)

Renal failure

Mineral

State of Catabolism

CommentsNormal

(mEq)

Mild-Mod(mEq)

Severe(mEq)

Potassium 0.7 - 0.9 2.0 3.0 - 4.0 Give 5 - 6 mEq/g of N infused

Sodium 1.0 - 4.0 2.0 - 3.0 3.0 - 4.0  

Calcium 0.22 0.3 0.4

0.25 m Eq/kg needed for calcium equilibrium. Dependent on simultaneous administration of PO and Na, not N retention

Phosphorous 0.3 0.8 1.2 - 2.0

Needs related to nitrogen retention which is related to kcal intake. Give 15-25 mEq PO per 1000 dex kcals.

Magnesium 0.3 0.3 - 0.4 0.6 - 0.8 Give 2 mEq per gram of N infused.

Mineral needs (Amount per kg body weight)

Mineral Needs Based on Laboratory DataMineral Lab Value Daily need

PotassiumAbove 4.8

4.0 - 4.83.5 - 3.9

Below 3.5

None20 - 30 mEq40 - 50 mEq80 - 90 mEq

SodiumAbove 142

136 - 142Below 136

None25 - 50 mEq50 - 100 mEq

CalciumAbove 10.5

8.0 - 10.57.0 - 7.9

None4.5 mEq9.0 m Eq

PhosphorousAbove 3.5

2.5 - 3.5Below 2.5

None15 mM

15 - 30 mM

ChlorideAbove 104

101 - 10498 - 100Below 90

None20 - 25 mEq40 - 50 mEq90 - 100 mEq

Magnesium 8.1 Eq  

Trace Elements Requirements for standard trace element mixtures are

to be monitored and adjusted based on serum concentrations.

Iron can be given intramuscularly as needed. • When transferrin levels are low, free iron increases and

can increase susceptibility to infections. • Critically ill or malnourished patients often have no

bone marrow response to iron.

Copper supplementation must be administered with caution to avoid toxicity.

Extra zinc may be needed by some patients to promote wound healing.

Element Dose

Zinc 2.5 - 4.0 mg

Copper 0.5 - 1.5 mg

Iron 1.0 mg

Chromium 10 - 15 mcg

Manganese 0.15 - 1.8 mg

Iodine 1 - 2 mcg

Selenium 20 - 40 mcg

Vitamins The vitamin requirements for TPN patients are different

from non-TPN patients because absorption is not a factor with TPN.

When needs are increased for certain disease states, single vitamin supplements can be added to the solution.

Serum vitamin levels can be monitored and dosage adjusted accordingly.

Vitamin preparations should be added to the TPN solution just prior to administration to avoid losses from light exposure.

Vitamin Supplementation Recommendations Vitamin Adults Children Under 11 years

A (IU) 3300 3300 3300

D(IU) 200 200 400

E(IU) 10 10 7

Thiamin (mg) 3 3 1-2

Riboflavin (mg) 3.6 3.6 1.4Pantothenic Acid

(mg) 40 40 17

Folate (mcg) 15 20 -

B-12 (mcg) 0.4 0.4 1.4

Biotin (mg) 5 5 1

C (mg) 100 100 80

THE END