surgical_nutrition(正式)外科营养PPT参考幻灯片

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;,4,Indications for enteral feeding,Malnourished patients who have an intact gastrointratina

3、l tract should initially be given enteral feeding.,5,Possible contraindications to enteral feeding,Short bowel, gastrointestinal obstruction, gastrointestinal bleeding, ileus, fistulas, diarrhea, protracted vomiting ect.,6,Parenteral nutrition,The gastrointestinal tract can not be used. Two methods:

4、 peripheral Parenteral nutrition and total Parenteral nutrition,l,7,8,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 m

5、onitoring, 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 instan

6、ces in which 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

7、 Calories 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

8、of a protein 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

9、. The body 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

10、in metabolism, 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 hospitali

11、sed patients 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 i

12、ntake 0.8 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,Nutritio

13、nal Balance = 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

14、as triglycerides 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 expe

15、nditure 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 Tra

16、uma1.3 x 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

17、system,25,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 nitro

18、gen, muscle 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

19、have lost 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 det

20、ect malnutrition?,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

21、and physical 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 begi

22、ns with 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

23、 the science 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

24、 impedance 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

25、requirement 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

26、Prothrombin 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 Im

27、munologic 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, Jev

28、ity Monomeric / 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 Diarrhoe

29、a Constipation 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 Nutritio

30、n,Allows 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

31、abe to eat 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,

32、Peripheral 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 Assessmen

33、t Venous 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,Ste

34、ps to administrate 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 bo

35、dy weight 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 + Activ

36、ity Factor 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

37、+ 20% Ambulant + 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

38、more than 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

39、CHO(carbohydrate) 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,6

40、6,Based 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 (

41、or 30 - 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 investigatio