Parenteral Nutrition Dr jitendra shuklaresident AH R&R

Until the early 1960s, the use of intravenous nutrition was restricted to high concentrations of dextrose and electrolytes.

In 1962, Wretlind and colleagues developed lipid infusions as the principle source of calories for parenteral feeding.

In 1966, Dudrick and Rhoads developed parenteral nutrition (PN) for patients who had lost their small bowel.

In 1976, Solassol and Joyeux developed the three-in-one mixture by putting sugars, lipids and amino acids in a single bag.

In 1978, Shils and colleagues and Jeejeebhoy and colleagues developed ‘home’ PN to reduce costs.

Human nutrition is the provision to obtain the essential nutrients necessary to support life and health

Nutrients are the substances that are not synthesized in sufficient quantity in the body and therefore must be supplied from diet

Macronutrients mainly carbohydrates, fats, protein, dietary fiber and water

Micronutrients: vitamins, minerals and trace elements

NUTRITION

Protein (Amino acids) Fat Carbohydrate Dietary fiber Water and electrolytes Vitamins minerals Trace elements

Essential Nutrients

Pts should be assessed for PEM as well as specific nutrient deficiencies

History: assess for change in diet pattern (size, number and content of meals)

Unintentional weight loss Evidence of malabsorption Symptoms of specific nutrient deficiencies Look for factors which may increase metabolic

stress (infection, inflammation, malignancy) Functional status (bed ridden, suboptimally

active, fully active)

ASSESSMENT OF NUTRITIONAL STATUS

By WHO criteria, pts can be classified by BMI as underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), class I obesity(30-34.9), class II obesity(35-39.9) class III obesity(>40)

Pts who are extremely underweight (BMI<14 kg/m2) or those with rapid, severe weight loss have high risk of death and should be considered for admission to the hospital for nutritional support

Examination and anthropometry

Look for tissue depletion(loss of body fat and skeletal muscle wasting)

Assess muscle function (strength testing of individual muscle groups)

Fluid status: dehydration or fluid overload Look for sources of protein or nutrient

losses: large wounds, burns, nephrotic syndrome, chronic diseases, GI losses of nutrients, surgical drains.

Lab parameters: plasma albumin, electrolytes, vitamins and minerals

Critical illness induces anorexia and the inability to eat normally, predisposing patients to serious nutritional deficits, muscle wasting, weakness, and delayed recovery, longer stay in hospital

For critically ill pts provision of specialized nutritional support considered which represent major advance in medical therapy

Although at least 15-20% of pts in acute care hospitals have evidence of significant malnutrition, only a small fraction will benefit from SNS

Specialized nutrition support

Nutritional support, via either enteral or parenteral routes, is used in three main settings:

(1) To provide adequate nutritional intake during recuperative phase of illness or injury

(2) to support the pts during systemic response to inflammation, injury or infection during an extended critical illness

(3) pts with permanent loss of intestinal length or function

Specialized nutrition support

Decision to use SNS should be based on the likelihood that preventing PEM will increase the likelihood of recovery, reduce infection rate, improve healing and shorten the stay in hospital

SNS should be recommended only when potential benefits exceed risks, and it should be undertaken with consent of the pt

Specialized nutrition support

Efficacy of SNS Efficacy studies have shown that

malnourished pts undergoing major thoracoabdominal surgery benefit from SNS, critical illness requiring ICU care, including major burns, major trauma, severe sepsis, closed head injuries and severe pancreatitis, all benefit from early nutritional support, as indicated by reduced mortality and morbidity

Refers to feeding via a tube placed into the gut to deliver liquid formulas containing all essential nutrients

Preferred route because of benefits derived from maintaining the digestive, absorptive and immunological barrier function of GIT

Enteral/tube feeding is useful in pts who have functional GIT, but who cannot digest or ingest adequate amount of nutrients

Short term (<6 weeks) tube feeding can be achieved by nasogastric, nasoduodenal or nasojejunal tubes

ENTERAL NUTRITION

Long term feeding (>6 wk) usually requires gastrostomy or jejunostomy tube that can be placed percutaneously by endoscopic (PEG) or radiographic assistance

Enteral feeding is often required in pts with anorexia, impaired swallowing, or bowel disease. The bowel and its associated digestive organs derive 70% of their required nutrients directly from food in lumen

Enteral formulas: standard (osmolality- 300) and modified

Complications of enteral feeding include mainly aspiration pneumonia and diarrhoea

ENTERAL NUTRITION

Enteral nutrition is associated with fewer complications than parenteral nutrition and is less expensive to administer.

However, the use of enteral nutrition alone often does not achieve caloric targets.

In addition, underfeeding is associated with weakness, infection, increased duration of mechanical ventilation, increased duration of hospital stay and death.

Combining parenteral nutrition with enteral nutrition constitutes a strategy to prevent nutritional deficit but may risk overfeeding which has been associated with liver dysfunction, infection, and prolonged ventilatory support.

ENTERAL Vs PARENTERAL

The consequences of major surgeries and PEM can lead to hypermetabolism and subsequent malnutrition. A strong association exist between malnutrition and increased post operative morbidity and mortality.

The administration of TPN can prevent the effects of starvation in pts with non functional GIT

Parenteral nutrition should be considered if energy intake has been inadequate for more than 7-10 days and enteral feeding is not feasible. (based on ICU focused meta- analysis discussed in 2009 ASPEN)

PARENTERAL NUTRITION

The gut should always be the preferred route for nutrient administration.

Therefore, parenteral nutrition is indicated generally when there is severe gastro-intestinal dysfunction (cannot take sufficient food or feeding formulas by the enteral route) .

It involves the continuous infusion of a hyperosmolar solution containing carbohydrates, proteins, fat and other necessary electrolytes through an indwelling catheter inserted into (usually) SVC to meet the nutritional needs of the patient.

PN through a peripheral vein is limited by osmolality and volume constraints

Solutions that contain more than 3% aminoacid and 5% glucose are poorly tolerated peripherally

Parenteral nutrition

Peripheral parenteral nutrition (PPN) administered through a peripheral intravenous

catheter.The osmolarity of PPN solutions generally is

limited to 1,000 mOsm (approximately 12% dextrose solution) to avoid phlebitis.

Thus, large volumes (>2,500 mL) are needed.Temporary nutritional supplementation with PPN

may be useful Generally intended as supplement to oral feeding

and is not optimal for critically ill pts

Types

Total parenteral nutrition (TPN) provides complete nutritional support The solution, volume of administration, and

additives are individualized based on an assessment of the nutritional requirements.

TPN formulation without lipid (2-in-1 solution)Calories from amino acids- 20 to 25%Calories from dextrose- 75-80%

TPN formulation with lipid ( 3-in-1 solution) calories from amino acids- 20 to 25% calories from lipids- 20% calories from dextrose- 55 to 60 %

Types of TPN formulations

Special solutions that contain low, intermediate, or high nitrogen concentrations as well as varying amounts of fat and carbohydrate are available for pts with diabetes, renal or pulmonary failure, or hepatic dysfunction.

Additives:Electrolytes (i.e., sodium, potassium,

chloride, acetate, calcium, magnesium, phosphate) should be adjusted daily.

The number of cations and anions must balance; this is achieved by altering the concentrations of chloride and acetate.

If the serum bicarbonate is low, the solution should contain more acetate.

The calcium:phosphate ratio must be monitored to prevent salt precipitation.

Medications:

Albumin, H2-receptor antagonists, heparin, iron, dextran, insulin, and metoclopramide can be administered in TPN solutions. However, not all medications are compatible with 3-in-1 admixtures.

Regular insulin should initially be administered subcutaneously according to a sliding scale, based on a determination of the blood glucose level. After a stable insulin requirement has been established, insulin can be administered in the TPN solution, generally at two thirds of the daily subcutaneous insulin dose.

Crystalline amino acid solutions containing 40-50% essential and 50-60% non essential amino acids are used to provide protein needs

Some amino acid solutions have been modified: rich in branched chain amino acids for hepatic encephalopathy, rich in essential amino acid for renal insufficiency pts

Glucose in IV solutions is hydrated; each gm of dextrose monohydrate provides 3.4 kcal. While there is no absolute requirement of glucose in most pts, providing >150g glucose/d maximizes protein balance

TPN- macronutrient solutions

Lipid emulsions are available as 10% (1.1kcal/ml) or 20% (2 kcal/ml) solutions and provide energy as well as source of essential fatty acids.

Rate of infusion should not exceed 1 kcal/kg/h

TPN- macronutrient solutions

Climomel N5-800 Clinimix N9G-20E Kabiven Vitrimix Celemix-G

Some commercial formulations available in India

gastrointestinal cutaneous fistulaRenal failure (ATN) Short bowel syndromeSevere burnsHepatic failureCrohn’s diseaseAnorexia nervosa Acute radiation enteritisAcute chemotherapy toxicityProlonged ileusWeight loss preliminary to major surgery

Indications

Energy Basal energy requirement is the function of the

individual's weight, age, gender, activity level and the disease process

The major components of energy output are resting energy expenditure and physical activity; minor sources include the energy cost of metabolizing food and shivering thermogenesis.

Total energy expenditure= resting energy expenditure (70% of TEE) +thermic effect of food (10% of TEE) + energy expenditure of physical activity (20% of TEE)

Requirements

Average energy intake is about 2600 kcal/d for men and 1900 kcal/d for female, though these estimates vary with body size and activity level

Formula for estimating REE are useful for assessing the energy needs of an individual whose weight is stable

For males, REE=900+10m, and for females, REE=700+7m, where m is mass in kilograms

Calculated REE is the adjusted for physical activity level (multiplying by 1.2 for sedentary, 1.4 for moderately active and 1.8 for very active)

TEE = REE + Stress Factor + Activity Factor

Rest Energy Expenditure Adults (18-65) 20-30 kcal/kg Elderly (65+) 25 kcal/kg For burns Patients 30-35kcal/kgOther factors: Pregnancy: Add 300 kcal/day Lactation: Add 500 kcal/day Obese or Super obese 15-20 kcal/kg

Caloric Requirement

peritonitis + 15%

• soft tissue trauma + 15%

• fracture + 20%

• fever (per oC rise) + 13%

• Moderate infection + 20%

• Severe infection + 40%

• <20% BSA Burns + 50%

• 20-40% BSA Burns + 80%

• >40% BSA Burns + 100%

Stress factor

BMI (kg/m2) Energy requirement (kcal/kg/d)

15 35-40

15-19 30-35

20-24 20-25

25-29 15-20

30 and >30 <15

Estimated energy requirements for hospitalized pts based on BMI

These values are recommended for critically ill pts and obese pts; add 20% of total calories in estimating energy requirement in non critically ill pts

Requirement 2g/kg/day 1grams=5kcal/g 40-50 percent of total nutrition Generally, because glucose is an essential

tissue fuel, glucose and amino acids are provided parenterally until the level of resting energy expenditure is reached. Fats are added thereafter

Carbohydrate Requirement

Requirement 3 g/kg/day 1 gram= 9kcal/g 30-40 percent of nutrition Liver can synthesize most fatty acids, but

humans lack the desaturase enzyme needed to produce n-3 and n-6 fatty acid series. Therefore linoleic acid should constitute at least 2% and linolenic acid at least 0.5% of daily caloric intake to prevent essential fatty acid deficiency

Fat Requirements

Clinical condition requirement

normal 0.8

Metabolic stress (illness, injury) 1.0-1.5

Acute renal failure (undialyzed) 0.8-1.0

hemodialysis 1.2-1.4

Peritoneal dialysis 1.3-1.5

Protein requirement

Additional protein intake may be needed to compensate for excess protein loss in specific patient population such as burn injuries, open wounds, protein losing Enteropathy / Nephropathy. A lower protein intake may be necessary in patient with chronic renal insufficiency who are not treated by dialysis and certain patients with hepatic encephalopathy

The standard enteral and parenteral formulas contain protein of high biological value and meet the requirements for the eight essential amino acids

Protein or nitrogen balance provides a measure of feeding efficacy of PN or EN

Calculated as protein intake/6.25 minus 24h urine urea nitrogen plus 4g nitrogen, which reflects the other losses

Protein requirement

Nitrogen Balance

Nitrogen Balance = N input - N output

6.25 g protein provides 1 g of nitrogen as 100grams contains 16 g nitrogen

N input = (protein in g / 6.25)

N output = 24h urinary urea nitrogen + non-urinary N losses

+4 to + 6: Net anabolism +1 to - 1: Homeostasis -2 to – 1: Net catabolism

ESTIMATING ADULT FLUID REQUIREMENTS By caloric intake : 1ml/calorie Example: 1800 calorie diet = 1800 calories

x 1ml= 1800ml By body weight and age : average

requirement is 30 ml/kg/d 16-55 years 35 ml/kg/d 56-65 years 30 ml/kg/d > 65 years 25 ml/kg/d

Fluid Requirments

Sodium 70 – 100 mEq/day Chloride 70 – 100 mEq/day Potassium 70 – 100 mEq/day Calcium 10 – 20 mEq/day Magnesium 15 – 20 mEq/day Phosphorus 40-60 mEq/day Acetate 0 – 60 mEq/day

Electrolyte Daily Requirements

Vitamin A 3300 IU Vitamin D 200 IU Vitamin E 10 IU Vitamin K - 150 mcg Ascorbic acid 100 mg Folic Acid 0.4 mg Niacin 40 mg Riboflavin (B2) 3.6 mg Thiamin (B1) 3 mg Pyridoxine (B6) 4 mg Cyanocobalamin (B12) 5 mcg Pantothenic acid 15 mg Biotin 60 mcg

Daily Parenteral Vitamins Supplementation

Zinc 2.5-4 mg Copper 0.5-1.5mg Chromium 10-15 mcg Selenium 20-60 mcg Manganese 150-800 mcg

Daily Parenteral Trace Element Supplementation

Introduction of TPN should be gradual. For example, approximately 1,000 kcal is provided the first day. If there is metabolic stability (i.e., normoglycemia), this is increased to the caloric goal over 1 to 2 days.

TPN solutions are delivered most commonly as a continuous infusion. A new 3-in-1 admixture bag of TPN is administered daily at a constant infusion rate over 24 hours. Additional maintenance intravenous fluids are unnecessary, and total infused volume should be kept constant while nutritional content is increased.

ADMINISTRATION OF TPN

Cyclic administration of TPN solutions may be useful for

(1) those who will be discharged from the hospital and subsequently receive home TPN,

(2) those with limited intravenous access who require administration of other medications, and

(3) those who are metabolically stable and desire a period during the day when they can be free of an infusion pump.

Cyclic TPN is administered for 8 to 16 hours, most commonly at night. This should not be done until metabolic stability has been demonstrated for patients on standard, continuous TPN infusions.

Cyclic Administration

Venous access The infusion of hyperosmoler nutrient

solution requires a large bore, high flow vessel to minimize vessel irritation and damage.

Percutaneous subclavian vein catheterization and PICC are the most commonly used techniques for parenteral nutrition

Catheter can be placed via the subclavian vein, the jugular vein (less desirable because of the high rate of associated infection), or a long catheter placed in an arm vein and threaded into the central venous system (a peripherally inserted central catheter line)

Position of catheter is confirmed by radiograph

Application:

PICC line

ADVANTAGES DISADVANTAGES

Bed side technique Avoids complications

of central venous catheter

Avoid multiple venous cannulations

Hypertonic solutions can be given

Trained personnel is needed

Line blockage Mal position Phlebitis Line sepsis thrombosis

Central Catheter(Non Tunneled)

advantages disadvantages

Central access needed Multiple lumen can be

used in acute emergency

Hypertonic solutions can be given

Can be placed for than 6 weeks

Inserted in theatre Increase infection rate Multiple complications

Central catheter (Tunneled)

advantages disadvantages

Convenient exit site Long lasting than non

tunnels Hypertonic solutions

can be given

Removal needs surgical dissection

Catheter related sepsis

Other complications

Monitoring of parenteral nutrition

Clinical Data Monitored Daily

General sense of well-being

Strength as evidenced in getting out of bed, walking, resistance exercise as appropriate

Vital signs including temperature, blood pressure, pulse, and respiratory rate

Fluid balance: weight at least several times weekly, fluid intake (parenteral and enteral) vs. fluid output (urine, stool, gastric drainage, wound, ostomy)

Parenteral nutrition delivery equipment: tubing, pump, filter, catheter, dressing

Nutrient solution composition

Laboratory Daily

Finger-stick glucose Three times daily until stable

Blood glucose, Na, K, Cl, HCO3, BUN Daily until stable and fully advanced, then twice weekly

Serum creatinine, albumin, PO4, Ca, Mg, Hb/Hct, WBC

Baseline, then twice weekly

INR Baseline, then weekly

Micronutrient tests As indicated

Discontinuation of TPN should take place when the patient can satisfy 75% of his or her caloric and protein needs with oral intake or enteral feeding.

To discontinue TPN, the infusion rate should be halved for 1 hour, halved again the next hour, and then discontinued.

Tapering in this manner prevents rebound hypoglycemia from hyperinsulinemia.

It is not necessary to taper the rate if the patient demonstrates glycemic stability.

Discontinuation of TPN

Complications Of TPN

Mechanical

metabolic

infectious

Air embolism pneumothorax hemothoraxCardiac tamponadeInjuries to arteries and veinsInjury to thoracic duct Brachial plexus injury

Mechanical Complications

Early or nutrient related hyperglycemia hypoglycemia hyperlipidemia refeeding syndrome

late or related to long term administration hepatic dysfunctionSteatosis, steatohepatitis, lipidosis, cholestasis,

cirrhosis biliary complications: acalculous cholecystitis, Gb

sludge, cholelithiasisMetabolic bone disease: osteomalaacia, osteopenia

Metabolic complications

Fluid overload Hypo/hypernatremia Hypercalcemia Hypo/hyperkalemia

Infection : Catheter related sepsis is most common life

threatening complication Causes: staph epidermidis and staph aureus,

enterococcus, candida, E coli, psuedomonas, klebsiella etc in immunocompromised pts

Severe electrolyte and fluid shifts that may result from refeeding after severe weight loss (PEM)

Hypophosphatemia is the hallmark of refeeding syndrome due to shift from fat to glucose metabolism.

Hypokalemia and hypomagnesemia ↓K and ↓PO4→ ATP deficiency which can be

life threatening.

Refeeding syndrome

Store reconstituted PN bags in a refrigerator until use Always use aseptic techniques while connecting and

infusing PN Always use an infusion set with in-built air vent and

0.2 m filter Never insert a needle for air venting in a PN bag Never add any medication to the PN bag Avoid frequent changes in the formulation of the PN

solution Infuse the prescribed volume and avoid wastage of

PN solution

Care of the parenteral nutrition (PN) mixture

Clinical trials and meta-analysis of parenteral feeding in the perioperative period have suggested that preoperative nutritional support may benefit some surgical patients, particularly those with extensive malnutrition.

Short-term use of parenteral nutrition in critically ill patients (duration <7 days) when enteral nutrition may have been instituted is associated with higher rates of infectious complications

Facts:

Parenteral feeding with complete bowel rest results in augmented stress hormone and inflammatory mediator response to an antigenic challenge .

In cancer patients, parenteral nutrition has not been shown to benefit clinical response, survival, or toxic effects of chemotherapy, while infectious complications increased.

Following severe injury, parenteral nutrition is associated with higher rates of infectious risks when compared with enteral feeding

Facts:

the early initiation of parenteral nutrition to supplement insufficient enteral nutrition during the first week after ICU admission in severely ill patients at risk for malnutrition appears to be inferior to the strategy of withholding parenteral nutrition until day 8 while providing vitamins, trace elements, and minerals. Late parenteral nutrition was associated with fewer infections, enhanced recovery, and lower health care costs

Facts:

Subjects receiving intravenous feedings and bowel rest had significantly exaggerated response to injury

Facts:

Remember!!!

Strict asepsis 24-hr TPN prepared at a time Changing infusion sets daily New amino acid, lipid bottles daily Separate IV access for other drugs Serum Na, K on alt. days; renal parameters biweekly; LFT, triglycerides weekly