AinShams university Faculty of Medicine Department of Anesthesiology

Ain-Shams university Faculty of Medicine Department of Anesthesiology, ICU, and Pain management CME Program – ICU course

Parenteral Nutrition By Ahmed El-Shaer, MD

Def. : a method of feeding patients by infusing a mixture of all necessary nutrients into the circulatory system, thus bypassing the GIT. Also referred to as: intravenous nutrition, parenteral alimentation, and artificial nutrition.

The gut should always be the preferred route for nutrient administration. Therefore, parenteral nutrition is indicated generally when there is severe gastrointestinal dysfunction (patients who cannot take sufficient food or feeding formulas by the enteral route).

Categories of PN If enteral feeding is completely stopped or ineffective, Total Parenteral Nutrition is used (TPN). If enteral feeding is just “not enough” , supplementation with Partial Parenteral Nutrition (PPN) is indicated.

INDICATIONS In well-nourished adults, 7 - 10 days of starvation with conventional intravenous support (using 5% dextrose solutions) is generally accepted. If the period of starvation is to extend beyond this time, or the patient is not wellnourished, Total Parenteral Nutrition (TPN) is necessary to prevent the potential complications of malnutrition.

Indications for TPN Short-term use Bowel injury, surgery, major trauma or burns Bowel disease (e. g. obstructions, fistulas) Severe malnutrition Nutritional preparation prior to surgery. Malabsorption - bowel cancer Severe pancreatitis Malnourished patients who have high risk of aspiration Long-term use (HOME PN) Prolonged Intestinal Failure Crohn’s Disease Bowel resection

Partial Parenteral Nutrition: PPN can be used to supplement Ordinary or Tube feeding esp. in malnourished patients. Indications: Short bowel syndrome Malabsorption disorders Critical illness or wasting disorders

Enteral versus parenteral nutrition As far as gastrointestinal failure is concerned, long term parenteral nutrition is a life-saving procedure. Enteral nutrition has the advantage over parenteral nutrition of lower % of infectious complications. Parenteral nutrition has been shown to lead to changes in intestinal morphology and function and an increase in permeability (with higher % of bacterial translocation)

Nutritional Requirements Energy: Glucose Lipid Amino acids (Nitrogen) Water and electrolytes Vitamins Trace elements

q. Energy ü Basal Requirements: energy requirements are a function of the individual's weight, age, gender, activity level and the disease process. ü The estimation of energy requirements for parenteral nutrition relies on predictive equations. ü Hospitalized adults require approximately 2530 kcal/ kg. BW/day. ü However, these requirements may be greater in patients with injury or infection.

Energy Requirements Patient condition Basal metabolic rate Approximate energy Requirement (kcal/kg/day) No postoperative complications, GIT fistula without infection Normal 25 -30 Mild peritonitis, long-bone fracture, mild to moderate injury, malnourished 25% above normal 30 -35 Severe injury or infection 50% above normal 35 -45 Burn 40 -100% of total body surface Up to 100% above normal 45 -80

Requirements: v Energy Sources: Glucose The most common source of parenteral energy supply is glucose, being: ØReadily metabolized in most patients, Øprovides the obligatory needs of the substrate , thus reducing gluconeogenesis and sparing endogenous protein. Ø 1 gm of glucose gives 4 Kcals. Most stable patients tolerates of 4 -5 mg. kg 1. Min-1, but insulin resistance in critically ill patients may lead to hyperglycemia even at these rates, so insulin should be incorporated acc. to blood sugar levels.

Requirements: v Energy Sources: Glucose Route Glucose in 5% solution can be safely administered via a peripheral vein, but higher concentrations require a central venous line. 20, 25, or even 50 % solutions are needed to administer meaningful amounts of energy to most patients for proper volume administration.

Requirements: v. Energy Sources: Lipid Fat mobilization is a major response to stress and infection. Triacylglycerol's are an important fuel source in those conditions, even when glucose availability is adequate. Need to be restricted in patients with hypertriglyceridemia.

Requirements: v. Energy Lipids Sources: Lipid are also a source for the essential fatty acids which are the building blocks for many of the hormones involved in the inflammatory process as well as the hormones regulating other body functions. Ideally, energy from fat should not exceed 40% of the total (usually 2030%).

Requirements: v Energy Sources: Lipid Fat emulsions can be safely administered via peripheral veins, provide essential fatty acids, and are concentrated energy sources for fluidrestricted patients. They are available in 10, 20 and 30% preparations. Though lipids have a calorific value of 9 Kcal/g, the value in lipid emulsions is 10 Kcal/g due to the contents of glycerol and phospholipids.

Requirements: q. Nitrogen Protein (or amino acids, the building blocks of proteins) is the functional and structural component of the body, so fulfilling patient’s caloric needs with nonprotein calories (fat and glucose) is essential. Protein requirements for most healthy individuals are 0. 8 g/kg/day.

Requirements: q Nitrogen With disease, poor food intake, and inactivity, body protein is lost with the resultant weakness and muscle mass wasting. Critically ill patients may need as high as 1. 52. 5 g protein/kg/day depending on the disease process: (major trauma or burn > infection or after surgery > standard) The amount should be reduced in patients with kidney or liver disease.

Requirements: q Nitrogen Daily Protein requirements Condition Example requirement Basic requirements Normal person 0. 5 -1 g/Kg Slightly increased requirements Post-operative, cancer, 1. 5 g/Kg inflammatory Moderately increased requirements Sepsis, polytrauma 2 g/Kg Highly increased requirements Peritonitis, burns, 2. 5 g/Kg Reduced requirements Renal failure, hepatic encephalopathy 0. 6 g/Kg

q Nitrogen Requirements: Nitrogen Balance = Protein intake in grams ÷ 6. 25 – UUN (in grams) + 3 The nitrogen lost in urine derives primarily from amino acids released by protein breakdown in response to catabolic mediators that include stress hormones (corticosteroids, catecholamines) and cytokines. It is a way to assess the sufficiency of protein intake for the patient.

Requirements: q Nitrogen Parenteral amino acid solutions provide all known essential amino acids. Available a. a. preparations are 3. 5 - 15 % (ie contains 3. 5 -15 gms of protein or a. a. s/100 m. L solution). 1 gm of protein = 0. 16 gm of N 2.

Requirements: q Nitrogen Special a. a. solutions are also available containing higher levels of certain a. a. s, most commonly the branched-chain ones (valine, leucine and isoleucine), aimed at the management of liver diseases, sepsis and other stress conditions. Conversely, solutions containing fewer a. a. s (primarily the essential ones) are available for patients with renal failure.

Requirements: q. Nitrogen Arginine was added to enteral formulae claiming positive effects on immune function and length of hospital stay. In some clinical trials, glutamineenriched solutions improved nitrogen balance and gut morphology.

Requirements: q. Fluids and electrolytes 20– 40 m. L/kg - daily – young adults 30 m. L/kg – daily – older adults Sodium, potassium, chloride, calcium, magnesium, and phosphorus ( as per the table) Daily lab tests to monitor electrolyte status

Requirements: q Fluids and electrolytes Nutrient Water Sodium Potassium Magnesium Calcium Phosphate Requirements (/Kg/day) 20 -40 m. L 0. 5 -1. 0 mmol 0. 1 -0. 2 mmol 0. 05 -0. 15 mmol 0. 2 -0. 5 mmol Chloride/Acetat e So a to maintain acid-base balance (normally 0. 5 mmol for Cl- , & 0. 1 m. Eq for Acetate)

Requirements: q Fluids and electrolytes Normalization of acid-base balance is a priority and constant concern in the management of critically ill patients. Most electrolytes can be safely added to the parenteral amino acid/dextrose solution. Sodium bicarbonate in high concentrations will tend to generate carbon dioxide at the acidic p. H of the amino acid/glucose mix.

Requirements: q. Vitamins These requirements are usually met when standard volumes of a nutrient mix are provided. Increased amounts of vits are usually provided to severely ill patients. Vitamins are either fat soluble (A, D, E, K) or water soluble (B, C). Separate multivitamin commercial preparations are now available for both.

Requirements: q. Vitamins Multivitamin formulations for parenteral use for adult patients usually contain 12 vitamins at levels estimated to provide daily requirements. Additional amounts can be provided separately when indicated. Most adult vitamin formulae do not contain vitamin K, which is added according to the patient’s coagulation status.

Requirements: q Trace minerals These are essential component of the parenteral nutrition regimen. A multi-element solution is available commercially, and can be supplemented with individual minerals. may be toxic at high doses. Iron is excluded, as it alters stability of other ingredients. So it is given by separate injection (iv or im).

Requirements: q Trace minerals excreted via the liver, such as copper and manganese, should be used with caution in patients with liver disease or impaired biliary function. Mineral Recommended dietary allowance (RDA) for daily oral intake (mg) Suggested daily intravenous intake (mg) Zinc 15 2. 5 -5 Copper 2 -3 0. 5 -1. 5 Manganese 2. 5 -5 0. 15 -0. 8 Chromium 0. 05 -0. 2 0. 01 -0. 015 Iron 10 (males)-18 (females) 3

Osmolarity: PPN: Maximum of 900 milliosmoles / liter TPN: as nutrient dense as necessary (>900 m. osmol and up as high as 3000). Amino acids (10 m. osmol/gm), dextrose (5 m. osmol/gm) and electrolytes (2 m. osmol /m. Eq) contribute most to the osmolarity, while lipids give 1. 5 m. osmol/gm.

Application: q. The Solution Manually mixed in hospital pharmacy or nutrition-mixing service, premixed solutions, Separate administration for every element alone in a separate line.

q Venous Application: access PPN: (<900 m. osmol/L): a peripheral line can be enough. TPN: Central venous access is fundamental, Ideally, the venous line should he usedexclusively 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) Once the correct position of the catheter has been established (usually by X ray), the infusion can begin.

q Initiation Application: of Therapy TPN infusion is usually initiated at a rate of 25 to 50 m. L/h. This rate is then increased by 25 m. L/h until the predetermined final rate is achieved. q Administration To ensure that the solution is administered at a continuous rate, an infusion pump is utilized to administer the solution. In hospitalized patients, infusion usually occurs over 22 -24 h/day. In ambulatory home patients, administration usually occurs overnight (12 -16 h).

Monitoring v. Policy: to monitor: 1 - Effecacy: electrolytes (S. Na, K, Ca, Mg, Cl, Ph), acid-base, Bl. Sugar, body weight, Hb. 2 - Complications: ALT, AST, Bil, BUN, total proteins and fractions. 3 - General: Input- Output chart. 4 - Detection of infection: Clinical (activity, temp, symptoms) WBC count (total & differential) Cultures

Monitoring

Complications of TPN Sepsis Pneumothorax Air embolism Clotted catheter line Catheter displacement Fluid overload Hyperglycemia Rebound Hypoglycemia

Complications of TPN v Catheter-related complications Catheter sepsis: which can be localized or systemic (skin portal, malnutrion, poor immunity). ccc by: fever, chills, ±drainage around the catheter entrance site, Leukocytosis, +ve cultures (blood & catheter tip). ttt: 1 - exclusion of other causes of fever 2 - short course of anti-bacterial and antifungal therapy (acc. to C&S) 3 - Catheter removal may be required

Complications of TPN Catheter sepsis (Cont. ): Prevention: a rigorous program of catheter care: ü Only i. v. nutrition solutions are administered through the catheter, no blood may be withdrawn from the catheter. ü Catheter disinfection and redressing 2 to 3 times weekly. ü The entrance site is inspected for signs of infection and if present, culture is taken or the catheter is removed. ü Other catheter-related complications: Thromboembolism, pneumothorax, vein or artery perforation, and superior vena cava thrombosis

Complications of TPN Metabolic Complications o Hyperglycemia (an elevated blood sugar): Associated with the infusion of excess glucose in the feeding solution or the diabetic-like state in the patient associated with many critical illnesses. It can result in an osmotic diuresis (abnormal loss of fluid via the kidney), dehydration, and hyperosmolar coma. ttt: decrease the amount of infused glucose (to<4 mg/kg/min) OR insulin can be administered (either S. C. inj. or incorporation in the infusion bag). v

Complications of TPN v. Metabolic Complications Hypertriglyceridemia (High S. Triglycerides) Associated with excess infusion of fat emulsion. N. B. Infusion of both glucose and fat emulsion in excess may result in pulmonary insufficiency. Excess glucose infusion –> excess carbon dioxide (CO 2) production a result of glucose metabolism. Excess lipid infusion --> the lipid particles may accumulate in the lungs and reduce the diffusion capacity of respiratory gases. o

Complications of TPN v Metabolic o Complications liver toxicity (also know as parenteral nutrition cholestasis): It causes severe cholestatic jaundice, elevation of transaminases, and may lead to irreversible liver damage and cirrhosis. Multiple causes have been proposed, including high infusion rates of aromatic amino acids, high proportion of energy intake from glucose, e. t. c. . There is no specific treatment, other than anticholestatic therapy.

Complications of TPN v. Metabolic Complications o Intestinal bacterial translocation: The lack of direct provision of nutrients to the intestinal epithelia during total parenteral nutrition Trophism and altered permeability of the GI mucosa, thus compromising any potential recovery of the patient’s ability for enteral feeding, and allowing bacterial entery to blood stream sepsis Prevention is to provide a minimal enteral nutrition supply to avoid or minimize this risk.

Complications of TPN v. Metabolic o Other Complications metabolic complications: Electrolyte imbalance, mineral imbalance, acid-base imbalance, toxicity of contaminants of the parenteral solution.

Complications of TPN v. Mechanical Complications Catheters and tubing may become clotted or twist and obstruct. Pumps may also fail or operate improperly.

HOME PARENTERAL NUTRITION Patients who are unable to eat and absorb adequate nutrients for maintenance over the long term may be candidates for home parenteral nutrition e. g. extensive Crohn's disease, mesenteric infarction, or severe abdominal trauma. patients must be able to master the techniques associated with this support system, be motivated, and have adequate social support at home.

HOME PARENTERAL NUTRITION A patient who is judged to be a candidate for home parenteral nutrition requires an indwelling Silastic catheter designed for long-term permanent use. The nutrient solutions are prepared weekly and delivered to the patient's home. The patient sets up the infusion system and attaches the catheter to the delivery tubing in the evening for infusion over the next 12 -16 h. The intravenous nutrition is terminated by the patient the next morning.

Among the indications for parentral nutrition Short bowl syndrome, T Surgical GIT resection followed by more than 5 days fasting in a cachectic patient, T Polytrauma, F Intractable malabsorption, T Prolonged mechanical ventilation F

For energy requirements hospitalized adults require approximately 25 -30 kcal/kg/day T A single measurement of energy expenditure by indirect calorimetry will provide a reliable estimate of average requirements. F The most common source of parenteral energy supply is glucose. T Glucose in 5% solution can be safely administered via a peripheral vein, T With severe infection or injury, basal metabolic rate rises about 25% above normal F

Regarding Nitrogen balance A 70 Kgs normal adult male requires about 60 gms of protein daily T Stress induces catabolic state and hence, a positive Nitrogen balance F Special amino acid solutions containing higher levels of branched-chain amino acids (valine, leucine and isoleucine) are useful in the management of liver diseases. T With renal failure, reduction of the amino acid load is recommended. T Glutamine is essential for gut function. F

During Monitoring of TPN Hyperglycemia can be tolerated so long as there is no ketosis F New-onset glucose intolerance in patients receiving TPN may represent an early sign of sepsis. T Serum levels of electrolytes including magnesium and phosphorus should be checked daily until stabilized, then two times daily. F Overfeeding the patients markedly increases metabolic and respiratory complications. T Indirect calorimetry is very useful in mechanically ventilated patients with an Fi. O 2 greater than 50%. F

Complications of parentral nutrition The most frequent catheter-related complication is SVC thrombosis F Catheter sepsis is characterized by the classic signs of infection: chills, fever, and white blood cell count is usually elevated T Hyperglycemia is a very serious, relatively common, problem T Excessive infusion of aromatic amino acids, glucose, and lipids may lead to the development of liver toxicity (cholestasis). T Excess glucose infusion leads to excess O 2 consumption, while with lipid infusion, the lipid particles may accumulate in the lungs and reduce the diffusion capacity of respiratory gases. F