surgical_nutrition(正式)外科营养.ppt

1、1,Surgical Metabolism and Nutrition,Dr. Ouyang Jun, MD, PhD the First Affiliated Hospital of Soochow University,2,Questions,What is surgical nutrition？ Benefits of Nutritional Support? Who requires nutritional support? How can we get nutritional support?,3,What is surgical nutrition？,The nutritional

2、 problems in surgical diseases Including enteral and parenteral nutrition,Enteral nutrition,Use of an intact gastrointestinal tract for nutritional support Benefits : physiologic ; immunologic ; saffety; cost;,Indications for enteral feeding,Malnourished patients who have an intact gastrointratinal

3、tract should initially be given enteral feeding.,Possible contraindications to enteral feeding,Short bowel, gastrointestinal obstruction, gastrointestinal bleeding, ileus, fistulas, diarrhea, protracted vomiting ect.,Parenteral nutrition,The gastrointestinal tract can not be used. Two methods: perip

4、heral Parenteral nutrition and total Parenteral nutrition,l,8,Benefits of Nutritional Support,Preservation of nutritional status Prevention of complications of protein malnutrition Post-operative complications ,9,Nutritional support, along with antibiotics, blood transfusion, critical care monitorin

5、g, advances in anesthesia, organ transplantation, and cardiopulmonary bypass, ranks high among advances in surgery achieved in the 20th century。,10,Although modern practice is to make aggressive use of the gut for nutritional support intravenous nutrition remains a critical therapy in instances in w

6、hich enteral support cannot be achieved either because the gut cannot be used or because caloric requirements cannot be met by the gut alone and must be supplemented parenterally.,11,NUTRIENT REQUIREMENTS AND SUBSTRATES,The body requires an energy source to remain in a steady state. Calories Calorie

7、s can come from glucose or fat. The metabolism of lg glucose yields 3.4kcal. The metabolism of lg fat yields 9. 2kcal. Fat can be used to provide as much as 60% of daily caloric requirements.,12,Protein,Protein balance reflects the sum of protein synthesis and protein breakdown. The quality of a pro

8、tein is related to its amino acid composition. The 20 amino acids are divided into essential amino acids (EAAs) and nonessential amino acids (NEAAs) depending on whether they can be synthesized in the body.,13,Fatty Acids,Fatty acids are classified as short-chain, medium-chain, or long-chain. The bo

9、dy is able to synthesize fats from other dietary substrates, but two of the long-chain fatty acids (linoleic and -linolenic) are essential. Efficient functioning of the immune system depends upon a balance of eicosanoid production between the-6 and -3 PUFA.,14,Vitamins,Vitamins are involved in metab

10、olism, wound healing, and immune function.,15,Trace Elements,Trace elements have important functions in metabolism, immunology, and wound healing. Subclinical trace element deficiencies occur in many common diseases.,16,Malnutrition Introduction,Malnutrition occurs in approx.40% of hospitalised pati

11、ents Malnutrition can lead to increased post-operative morbidity and mortality Impairment of skeletal, cardiac, respiratory muscle function Impairment of immune function Atrophy of GIT Impaired healing,17,Nutritional Pathophysiology,18,Pathophysiology,Proteins and amino acids Require daily intake 0.

12、8 g kg-1 ie. 56 g for a 70 kg person Essential: a.a only obtained by dietary source Non-essential: can be endogenously synthesised conditionally essential: a.a unable to be synthesised under certain conditions eg. Stress, surgery L-alanine, L-glutamate, L-asparate,19,Pathophysiology,Nutritional Bala

13、nce = N input - N output 1 g N= 6.25 g protein N input = (protein in g / 6.25) N output = 24h urinary urea nitrogen + non-urinary N losses (estimated normal non-urinary Nitrogen losses about 3-4g/d),20,Fatty acids Short, medium chain FA directly enter portal system Long chain FA transported as trigl

14、ycerides Essential FA unable to be synthesised ie. Linoleic and linolenic acid. Deficiency causes skin, kidney disorders,Pathophysiology,21,Pathophysiology,Energy requirements: Total daily expenditure 25-30 kcal kg-1 Resting metabolic rate Activity energy expenditure Diet induced energy expenditure

15、Sources: Fats9 kcal g-1 Protein4 kcal g-1 Carbohydrates4 kcal g-1 Alcohol 7 kcal g-1,22,Patho-physiology,Energy requirements: BMR calculated by Harris-Benedict equation 66.47 + 13.75 x W + 5 x H 6.76xA Additional caloric needs calculated by an injury factor, eg. Minor operation 1.2 x BMR Trauma1.3 x

16、 BMR Sepsis 1.6 x BMR Burns2.1 x BMR,23,Pathophysiology,Vitamins Key metabolic roles Fat soluable (A, D, E, K) or water soluable,24,Pathophysiology,Trace elements Zinc wound healing, protein and nucleic acid synthesis Fe energy transfer Copper collagen synthesis Selenium anti-oxidant enzyme system,2

17、5,Pathophysiology,Changes in Starvation: decrease energy expenditure, liver glycogen depletion in 24h hepatic and muscle gluconeogenesis depleted after 24h later consume fat,26,Pathophysiology,Changes in trauma and sepsis Catabolic phase Increase resting energy expenditure Loss of body nitrogen, mus

18、cle breakdown Increase glucose production (glycogenolysis), deplete liver stores Increase lipolysis Early anabolic phase Late anabolic phase,27,Who requires nutritional support?,Patients already with malnutrition - surgery/trauma/sepsis Patients at risk of malnutrition Surgical patients who have los

19、t more than 10% of their customary body weight will have delayed wound healing and an incridence of postoperative complications.,28,Patients at risk of malnutrition,Depleted reserves Cannot eat for 5 days Impaired bowel function Critical Illness Need for prolonged bowel rest,29,How do we detect maln

20、utrition?,30,Nutritional Assessment,History Physical examination Anthropometric measurements Laboratory investigations,31,History,Dietary history Significant weight loss within last 6 months 15% loss of body weight compare with ideal weight Beware the patient with ascites/ oedema,32,History and phys

21、ical examination,The nutritional assessment is based on information from the history and physical examination. A complete medical history is essential to identify factors that predispose the patient to an altered nutritional status.,33,Physical Examination,A careful physical examination begins with

22、an overall assessment of the patients appearance. Evidence of muscle wasting Depletion of subcutaneous fat Peripheral oedema, ascites Features of Vitamin deficiency eg nail and mucosal changes Echymosis and easy bruising Easy to detect 15% loss,34,Anthropometric Measurements,Anthropometry is the sci

23、ence of assessing body size, weight, and proportions. Ideal body weight (IBW)=Height(cm)-l00 x0.9 Body mass index (BMI)=Weight(kg) /Height (m2),35,Anthropometric Measurements,Weight for Height comparison Body Mass Index (10% decrease) Triceps-skinfold Mid arm muscle circumference Bioelectric impedan

24、ce Hand grip dynamometry Urinary creatinine / height index,36,Laboratory Data,The visceral protein reserve is estimated from the serum total protein, albumin, and transferrin levels; total lymphocyte count; and antigen skin testing.,37,Determining Energy Requirements,The adult daily caloric requirem

25、ent is calculated by using the total energy expenditure (TEE) equation ,which includes three variables-height,weight,and age,38,Lab investigations,albumin 30 mg/dl pre-albumin 12 mg/dl transferrin 150 mmol/l total lymphocyte count 1800 / mm3 tests reflecting specific nutritional deficits eg Prothrom

26、bin time Skin anergy testing,39,How can we administrate nutritional support?,40,Nutritional Support,Types Enteral Nutrition Parenteral Nutrition,41,Enteral Feeding is best,Enteral nutrition(EN): use of intact gastrointestinal tract for nutritional support Benefits: Physiologic & Metabolic Immunologi

27、c Safety Cost,42,Indications of Enteral Feeding,When nutritional suport is needed Functioning gut present No contra-indications no ileus no recent anastomosis of gut no fistula,43,What can we give in tube feeding?,Blenderised feeds Commercially prepared feeds Polymeric eg Isocal, Ensure, Jevity Mono

28、meric / elemental eg Vivonex,44,Complications of enteral feeding,12% overall complication rate Gastrointestinal complications Mechanical complications Metabolic complications Infectious complications,45,Complications of enteral feeding,Gastrointestinal Distension Nausea and vomiting Diarrhoea Consti

29、pation Intestinal ischaemia,46,Complications of enteral feeding,Mechanical Malposition of feeding tube Sinusitis Ulcerations / erosions Blockage of tubes,47,Complications of enteral feeding,Infectious Aspiration Pneumonia Bacterial contamination,48,Parenteral Nutrition,49,Parenteral Nutrition,Allows

30、 greater caloric intake BUT Is more expensive Has more complications Needs more technical expertise,50,Who will benefit from parenteral nutrition?,51,Indications,Patients with/who Abnormal Gut function Cannot consume adequate amounts of nutrients by enteral feeding Are anticipated to not be abe to e

31、at orally by 5 days Prognosis warrants aggressive nutritional support,52,Two main forms of parenteral nutrition,Peripheral Parenteral Nutrition Central (Total) Parenteral Nutrition Both differ in,composition of feed primary caloric source potential complications methods of administration,53,Peripher

32、al Parenteral Nutrition,Given through peripheral vein short term use mildly stressed patients low caloric requirements needs large amounts of fluid contraindications to central TPN(total parenteral nutrition),54,Total Parenteral Nutrition,What to do before starting TPN? Nutritional Assessment Venous

33、 access evaluation Baseline weight Baseline lab investigations,55,Venous Access for TPN,Need venous access to a “large” central line with fast flow to avoid thrombophlebitis,Long peripheral line subclavian approach internal jugular approach external jugular approach,Superior Vena Cava,56,Steps to ad

34、ministrate TPN,Determine Total Fluid Volume Determine Non-N Caloric needs Determine Protein requirements Determine Electrolyte and Trace element requirements Determine need for additives,57,How much volume to give?,Cater for maintenance & on going losses Normal maintenance requirements By body weigh

35、t alternatively, 30 to 50 ml/kg/day Add on going losses based on I/O chart Consider insensible fluid losses also eg add 10% for every oC rise in temperature,58,Caloric requirements,Based on Total Energy Expenditure Can be estimated using predictive equations TEE = REE + Stress Factor + Activity Fact

36、or Can be measured using metabolic cart,59,Caloric requirements,Stress Factor,Malnutrition- 30% peritonitis+ 15% soft tissue trauma+ 15% fracture+ 20% fever (per oC rise)+ 13%,Moderate infection+ 20% Severe infection + 40% 40% BSA Burns+ 100%,60,Caloric requirements,Activity Factor,Bed-bound+ 20% Am

37、bulant + 30% Active + 50%,61,Caloric requirements,REE Predictive equations Harris-Benedict Equation Males: REE = 66 + (13.7W) + (5H) - 6.8A Females: REE= 655 + (9.6W) + 1.8H - 4.7A Schofield Equation 25 to 30 kcal/kg/day,62,How much CHO & Fats?,“Too much of a good thing causes problems” Not more tha

38、n 4 mg / kg / min Dextrose (less than 6 g / kg / day) Not more than 0.7 mg / kg / min Lipid (less than 1 g / kg / day),63,How much CHO & Fats?,Fats usually form 25 to 30% of calories Not more than 40 to 50% Increase usually in severe stress Aim for serum TG levels 350 mg/dl or 3.95 mmol / l CHO(carb

39、ohydrate) usually form 70-75 % of calories,64,How much protein to give?,Based on calorie : nitrogen ratio Based on degree of stress & body weight Based on Nitrogen Balance,65,Calorie : Nitrogen Ratio,Normal ratio is 150 cal : 1g Nitrogen Critically ill patients 85 to 100 cal : 1 g Nitrogen,66,Based

40、on Stress & BW,Non-stress patients0.8 g / kg / day Mild stress 1.0 to 1.2 g / kg / day Moderate stress1.3 to 1.75 g / kg / day Severe stress2 to 2.5 g / kg / day,67,Electrolyte Requirements,Cater for maintenance + replacement needs Na+1 to 2 mmol/kg/d (or 60-120 meq/d) K+0.5 to 1 mmol/kg/d (or 30 -

41、60 meq/d) Mg+0.35 to 0.45 meq/kg/d(or 10 to 20 meq /d) Ca+0.2 to 0.3 meq/kg/d(or 10 to 15 meq/d) PO42-20 to 30 mmol/d,68,Trace Elements,Total requirements not well established Commercial preparations exist to provide RDA(recommended dietary allowance) Zn2-4 mg/day Cr10-15 ug/day Cu0.3 to 0.5 mg/day Mn0.4 to 0.8 mg/day,69,TPN Monitoring,Clinical Review Lab investigation