ADVANCES IN SURGICAL NUTRITION.

MODERATOR- PROF. P.P. DAS

PRESENTER- DR. DWIPEN KALITA.2ND YEAR PG TRAINEE.

INTRODUCTION

• The goal of nutritional support in the surgical patient is to prevent or reverse the catabolic effects of disease or injury.

• Several important biologic parameters have been used to measure the efficacy of nutrition regimens.

• The ultimate validation for nutritional support in surgical patients should be improvement in clinical outcome and restoration of function.

• Estimating Energy Requirements

1. Determine the severity of nutrient deficiencies or excess 2. Predicting nutritional requirements

EVALUATION

GOAL OF NUTRITIONAL SUPPORT •the energy requirements for metabolic

processes •core temperature maintenance, •tissue repair. Requirement for energy may be measured by

•indirect calorimetry •urinary nitrogen excretion.

Harris-Benedict equations:

• The requirements for vitamins and essential trace minerals usually can be easily met in the average patient with an uncomplicated postoperative course.

• Patients maintained on elemental diets or parenteral hyperalimentation require complete vitamin and mineral supplementation.

• Commercial enteral diets contain varying amounts of essential minerals and vitamins.

• Commercial vitamin preparations are does not contain vitamin K and some do not contain vitamin B12 or folic acid.

• Overfeeding usually results from overestimation of caloric needs.

• Risk of overfeeding: increased oxygen consumption, increased CO2

production, fatty liver, suppression of leukocyte function, and increased infectious condition.

ROUTES OF FEEDING

• Enteral Nutrition Enteral nutrition generally is preferred over

parenteral nutrition based on reduced cost and associated risks of the intravenous route.

Access for Enteral Nutritional Support

ENTERAL FORMULAS

Factors that influence the choice of enteral formula:

•The extent of organ dysfunction (e.g., renal, pulmonary, hepatic, or gastrointestinal).

•The nutrient needs to restore optimal function and healing.

• The cost of specific products.

• Low-Residue Isotonic Formulas. Most provide a caloric density of 1.0 kcal/mL, and approximately 1500 to 1800 mL are required to meet daily requirements.

• Isotonic Formulas with Fiber. These formulas

contain soluble and insoluble fiber which are most often soy based.

. Immune-Enhancing Formulas. fortified with special nutrients that are purported to enhance various aspects of immune or solid organ function.

• Calorie-Dense Formulas. greater caloric value for the same volume. Most commercial products of this variety provide 1.5 to 2 kcal/M.

• High-Protein Formulas. High-protein formulas are available in isotonic and nonisotonic mixtures and are proposed for critically ill or trauma patients with high protein requirements.

• Elemental Formulas. These formulas contain predigested nutrients and provide proteins in the form of small peptides.

• Renal-Failure Formulas. The primary benefits of the renal formula are the lower fluid volume and concentrations of potassium, phosphorus, and magnesium needed to meet daily calorie requirements.

• Pulmonary-Failure Formulas. In these formulas, fat content is usually increased to 50% of the total calories, with a corresponding reduction in carbohydrate content.

• Hepatic-Failure Formulas. Close to 50% of the proteins in this formula are branched-chain amino acids (e.g., leucine, isoleucine, and valine).

COMPLICATIONS OF ENTERAL NUTRITION

• Tube related- Malposition Displacement Blockage Breakage Skin/Mucosa erosion• Gastrointestinal related- Diarrhoea Bloating, nausea,vomiting. Abdominal cramp Aspiration Constipation

• Metabolic related- Electrolyte disorder. Vitamin, mineral, trace element deficiency Drug interaction• Infective related- Exogenous (Handing complication) Endogeneous(patient)

PARENTERAL NUTRITION

INDICATIONS :1.Primary therapy Efficacy shown_ - Gastrointestinal cutaneous fistulas - Renal failure (acute tubular necrosis) - Short-bowel syndrome - Acute burns - Hepatic failure (acute decompensation

superimposed on cirrhosis) Efficacy not shown - -Crohn's disease. -Anorexia nervosa.

2.SUPPORTIVE THERAPY Efficacy shown_ -Acute radiation enteritis. -Acute chemotherapy toxicity. -Prolonged ileus . -Weight loss preliminary to major surgery. Efficacy not shown- -Before cardiac surgery. -Prolonged respiratory support. -Large wound losses.

3.Areas Under Intensive Study _ -Patients with cancer. -Patients with sepsis.

ESTIMATION OF CALORIC REQUIREMENT

• Underweight patient ABW is used as the feeding weight. • Obese (ABW is >120% of IBW) Add 25% of the difference between ABW and

IBW to the IBW as the feeding weight. • If no reliable weight is available, IBW alone is used.

Cont…

• Caloric requirements for TPN administration 25 to 35 kcal/kg/day for the rate of caloric infusion.

• This approach is safe, easy, and the most commonly used in clinical practice.

Formulation of the TPN Solution

• Minimal fluid requirements in the absence of GI or other losses are 25 to 35 mL/kg/day.

• In a 70-kg person.

Total kilocalories (25-35 kcal/kg/day): 30×70 = 2100 kcal

Protein (1.5 g/kg/day): 1.5×70 = 105 g amino acids

Cont…1. For TPN formulated without lipid (2-in-1

solution):

Total kilocalories = 2100 kcal Calories from amino acids = 105 g×4 kcal/g = 420 kcal Remaining calories = 2100 - 420 = 1680 kcal Then make up the difference with dextrose: 1680 kcal ÷ 3.4 kcal/g = 494 g dextrose

Cont…

• 2. For TPN formulated with lipid (3-in-1 solution): Total kilocalories = 2100 kcal Provide 20% of the total calories

Lipid = 2100×0.2 = 420 kcal 420 kcal ÷ 9 kcal/g = 47 g lipid

Calories from amino acids: 105 g×4 kcal/g = 420 kcal

Remaining calories: 2100 - 420 - 420 = 1260 kcal Then make up the difference with dextrose: 1260 kcal ÷ 3.4 kcal/g = 370 g dextrose Final volume (for 3-in-1, maximally concentrated): Amino acids (10% stock solution): 105 g = 1050 mL Dextrose (70% stock solution): 370 g = 528 mL Lipids (20% stock solution): 47 g = 235 mL Total volume = 1813 mL/day

Cont…

Management of Insulin

• 1. Never increase the amount of dextrose in the TPN solution until blood sugar is well controlled (i.e., <150 mg/dL).

• 2. Determine the amount of sliding-scale insulin administered over the previous 24 hours and add half to two thirds of that amount to the new TPN solution for the ensuing 24 hours.

• 3. When advancing the dextrose content of the TPN solution, advance the insulin concentration proportionally.

Mandatory Monitoring During Intravenous Nutrition

• Clinical: Daily fluid balance, body weight, evidence of infection• Laboratory: Baseline: Electrolytes, BUN, creatinine, glucose, calcium,

magnesium, inorganic phosphate, liver function (bilirubin, alanine transaminase, aspartate transaminase, alkaline phosphatase), triglyceride, albumin, prothrombin time.

• Every 6 to 12 hours: Glucose, usually for the initial 3 to 5 days

or until stable

• Daily until stable: Electrolytes, BUN, creatinine, glucose, calcium, magnesium, PO4

• • Weekly: Liver function, triglyceride, albumin, prothrombin time

PERIPHERAL PARENTERAL NUTRITION• The lower osmolarity solution used for peripheral

parenteral nutrition (PPN), secondary to reduced dextrose (5 to 10%) and protein (3%) levels, allows for its administration via peripheral veins.

• Some nutrients cannot be supplemented due to inability to concentrate them into small volumes.

• Not appropriate for repleting patients with severe malnutrition.

• can be considered if central routes are not available or if supplemental nutritional support is required.

• Typically, PPN is used for short periods (<2 weeks). Beyond this time, TPN should be instituted.

Home Parenteral Nutrition• Home parenteral alimentation is generally

cycled and performed overnight over an 8- to 14-hour period.

• Indications for Long-Term Parenteral Nutrition: - Short-gut syndrome - GI motility disorders -high-output enterocutaneous fistula, - Intractable chylous ascites, - Active Crohn's disease, - Cystic fibrosis, - Chronic pancreatitis,and

Cont… -some patients with cancer :

1) a curable malignancy requiring aggressive treatment resulting in anorexia, ileus, or intolerance to GI feeding.

(2) a cured patient with residual bowel dysfunction secondary to radiation enteritis or short-gut syndrome.

COMPLICATIONS OF TPN

• Technical Complications -Catheter Sepsis -Catheter Thrombosis -Pneumothorax, -Vascular injuries (arterial or venous lacerations,

delayed arteriovenous fistulas), -Brachial plexus injury, chronic pain, thoracic duct

injury after left-sided cannulation, air embolism, and catheter embolism. Erosion of the catheter into the bronchus, right atrium, or other structures may occur.

Metabolic complications

-Liver Disease : Hepatic dysfunction is commonly

observed in patients receiving TPN. -Metabolic Bone Disease -Hyperglycemia -Electrolyte imbalance

Cont…

Intestinal Atrophy Lack of intestinal stimulation is associated

with intestinal mucosal atrophy, diminished villous height, bacterial overgrowth, reduced lymphoid tissue size, reduced IgA production, and impaired gut immunity

Advantages of Enteral Versus Parenteral Feeding

When possible, the gut should be used preferentially for the following reasons:

1. Enteral feeding is much less expensive. 2. It probably improves hepatic function and mimics the

normal ingress of nutrients to the liver 3. Gut mucosal integrity is probably maintained,

particularly in patients with burns and hemorrhagic shock

4. Enteral nutrition may have beneficial effects on nonintestinal mucosa, possibly mediated by IgA secretion by the liver

Modulation of the Immune Response by Diet, or Immunonutrition

• Specific nutrients, such as arginine, nucleotides and ω-3 fatty acids have been shown to modulate the host response in experimental animals, with potential improvements in immune function.

Nutritional Pharmacology: Conditionally Essential and Other Special Metabolites in Critical Illness

• Nutritional pharmacology is a poorly defined, but often used term that emphasizes the role of particular nutrients to change the pathophysiology of a disease process, presumably by distinct molecular mechanisms.

• Glutamine -Within 24 hours of surgery or trauma, levels of free intracellular glutamine fall in many tissues and do not return to normal until as long as 8 weeks later

• Arginine-deficiency of arginine and dibasic amino acids in the plasma of patients with overwhelming sepsis was observed as early as 1978

• The ketone bodies - beneficial effect on the gut • Branched-Chain Amino Acids -BCAAs promote positive nitrogen balance in

muscle• Used for management of hepatic encephalopathy and uremia.

Cont…

• Essential Amino Acids- Most amino acids can be recycled, provided that energy is adequate. Thus, small amounts of essential amino acids with adequate energy are sufficient for nitrogen equilibrium

• Purines and Pyrimidine - essential under conditions of stress, potentially limiting cell division and the generation of new immune or other cells.

FUTURE DIRECTIONS IN ARTIFICIAL NUTRITION:

• Besides the primarily nutritional approaches additional strategies are available and are a focus of present and future research.

• Certain initially promising approaches, such as administration of growth hormone, have not been clearly shown to be of clinical benefit,whereas others, such as pharmacologic inhibition of protein breakdown, are in their infancy.

Cont…

• Catecholamines -exert an anabolic effect on muscle principally by reducing calcium-dependent proteolysis and by increasing protein synthesis.

• Inhibition of Proteolysis -• Pharmacologic Inhibition• Lessons From Nature -• Muscle proteolysis is suppressed in certain

physiologic conditions, including dietary protein deficiency and prolonged fasting.[

Thank you