surgical_nutrition(正式)外科营养

1、.1Surgical Metabolism and NutritionDr. Ouyang Jun, MD, PhDthe First Affiliated Hospital of Soochow University.2Questions nWhat is surgical nutrition？nBenefits of Nutritional Support?nWho requires nutritional support?nHow can we get nutritional support?.3What is surgical nutrition？nThe nutritional pr

2、oblems in surgical diseasesnIncluding enteral and parenteral nutrition.4Enteral nutritionnUse of an intact gastrointestinal tract for nutritional supportnBenefits : physiologic ; immunologic ; saffety; cost;.5Indications for enteral feedingnMalnourished patients who have an intact gastrointratinal t

3、ract should initially be given enteral feeding.6Possible contraindications to enteral feedingnShort bowel, gastrointestinal obstruction, gastrointestinal bleeding, ileus, fistulas, diarrhea, protracted vomiting ect.7Parenteral nutritionnThe gastrointestinal tract can not be used.nTwo methods: periph

4、eral Parenteral nutrition and total Parenteral nutritionl.8Benefits of Nutritional SupportnPreservation of nutritional statusnPrevention of complications of protein malnutrition nPost-operative complications .9nNutritional support, along with antibiotics, blood transfusion, critical care monitoring,

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

6、ich enteral support cannot be achievedneither because the gut cannot be used or because caloric requirements cannot be met by the gut alone and must be supplemented parenterally. .11NUTRIENT REQUIREMENTS AND SUBSTRATES nThe body requires an energy source to remain in a steady state. nCalories nCalor

7、ies 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. .12ProteinnProtein balance reflects the sum of protein synthesis and protein breakdown. The quality of a p

8、rotein 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. .13Fatty Acids nFatty acids are classified as short-chain, medium-chain, or long-chain. nTh

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

10、 metabolism, wound healing, and immune function. .15Trace Elements nTrace elements have important functions in metabolism, immunology, and wound healing. nSubclinical trace element deficiencies occur in many common diseases. .16Malnutrition IntroductionnMalnutrition occurs in approx.40% of hospitali

11、sed patientsnMalnutrition can lead to increased post-operative morbidity and mortalitynImpairment of skeletal, cardiac, respiratory muscle functionnImpairment of immune functionnAtrophy of GITnImpaired healing.17Nutritional Pathophysiology.18PathophysiologynProteins and amino acidsnRequire daily int

12、ake 0.8 g kg-1 ie. 56 g for a 70 kg personnEssential: a.a only obtained by dietary sourcenNon-essential: can be endogenously synthesisednconditionally essential: a.a unable to be synthesised under certain conditions eg. Stress, surgerynL-alanine, L-glutamate, L-asparate.19PathophysiologyNutritional

13、Balance = N input - N output1 g N= 6.25 g proteinN 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).20nFatty acidsnShort, medium chain FA directly enter portal systemnLong chain FA transported as trig

14、lyceridesnEssential FA unable to be synthesised ie. Linoleic and linolenic acid.nDeficiency causes skin, kidney disordersPathophysiology.21PathophysiologynEnergy requirements:nTotal daily expenditure 25-30 kcal kg-1nResting metabolic ratenActivity energy expenditurenDiet induced energy expenditurenS

15、ources:nFats9 kcal g-1nProtein4 kcal g-1nCarbohydrates4 kcal g-1nAlcohol 7 kcal g-1.22Patho-physiologynEnergy requirements:nBMR calculated by Harris-Benedict equationn66.47 + 13.75 x W + 5 x H 6.76xAnAdditional caloric needs calculated by an injury factor, eg.nMinor operation 1.2 x BMRnTrauma1.3 x B

16、MRnSepsis 1.6 x BMRnBurns2.1 x BMR.23PathophysiologynVitaminsnKey metabolic rolesnFat soluable (A, D, E, K) or water soluable.24PathophysiologynTrace elementsnZinc wound healing, protein and nucleic acid synthesisnFe energy transfernCopper collagen synthesisnSelenium anti-oxidant enzyme system.25Pat

17、hophysiologynChanges in Starvation: ndecrease energy expenditure, liver glycogen depletion in 24hnhepatic and muscle gluconeogenesis depleted after 24hnlater consume fat.26PathophysiologynChanges in trauma and sepsisnCatabolic phasenIncrease resting energy expenditurenLoss of body nitrogen, muscle b

18、reakdownnIncrease glucose production (glycogenolysis), deplete liver storesnIncrease lipolysisnEarly anabolic phasenLate anabolic phase.27Who requires nutritional support?nPatients already with malnutrition - surgery/trauma/sepsisnPatients at risk of malnutritionnSurgical patients who have lost more

19、 than 10% of their customary body weight will have delayed wound healing and an incridence of postoperative complications.28Patients at risk of malnutritionnDepleted reservesnCannot eat for 5 daysnImpaired bowel functionnCritical Illness nNeed for prolonged bowel rest.29How do we detect malnutrition

20、?.30Nutritional AssessmentnHistory nPhysical examinationnAnthropometric measurementsnLaboratory investigations.31HistorynDietary historynSignificant weight loss within last 6 monthsn 15% loss of body weightncompare with ideal weightnBeware the patient with ascites/ oedema.32History and physical exam

21、inationnThe nutritional assessment is based on information from the history and physical examination. nA complete medical history is essential to identify factors that predispose the patient to an altered nutritional status. .33Physical ExaminationnA careful physical examination begins with an overa

22、ll assessment of the patients appearance. nEvidence of muscle wastingnDepletion of subcutaneous fatnPeripheral oedema, ascitesnFeatures of Vitamin deficiencyneg nail and mucosal changesnEchymosis and easy bruisingnEasy to detect 15% loss.34Anthropometric Measurements n Anthropometry is the science o

23、f assessing body size, weight, and proportions. n Ideal body weight (IBW)=Height(cm)-l00 x0.9n Body mass index (BMI)=Weight(kg) /Height (m2) .35Anthropometric MeasurementsnWeight for Height comparisonnBody Mass Index (10% decrease)nTriceps-skinfold nMid arm muscle circumferencenBioelectric impedance

24、nHand grip dynamometrynUrinary creatinine / height index.36Laboratory Data nThe visceral protein reserve is estimated from the serum total protein, albumin, and transferrin levels; total lymphocyte count; and antigen skin testing. .37Determining Energy RequirementsnThe adult daily caloric requiremen

25、t is calculated by using the total energy expenditure (TEE) equation ,which includes three variables-height,weight,and age .38Lab investigationsnalbumin 30 mg/dlnpre-albumin 12 mg/dlntransferrin 150 mmol/lntotal lymphocyte count 1800 / mm3ntests reflecting specific nutritional deficitsneg Prothrombi

26、n timenSkin anergy testing.39How can we administrate nutritional support?.40Nutritional SupportnTypes nEnteral NutritionnParenteral Nutrition .41Enteral Feeding is bestnEnteral nutrition(EN): use of intact gastrointestinal tract for nutritional supportnBenefits:nPhysiologic & MetabolicnImmunolog

27、icnSafetynCost.42Indications of Enteral FeedingnWhen nutritional suport is needednFunctioning gut presentnNo contra-indicationsnno ileusnno recent anastomosis of gutnno fistula.43What can we give in tube feeding?nBlenderised feedsnCommercially prepared feeds nPolymeric neg Isocal, Ensure, JevitynMon

28、omeric / elemental neg Vivonex.44Complications of enteral feedingn12% overall complication ratenGastrointestinal complicationsnMechanical complicationsnMetabolic complicationsnInfectious complications.45Complications of enteral feedingnGastrointestinalnDistensionnNausea and vomiting nDiarrhoeanConst

29、ipationnIntestinal ischaemia.46Complications of enteral feedingnMechanicalnMalposition of feeding tubenSinusitisnUlcerations / erosionsnBlockage of tubes.47Complications of enteral feedingnInfectiousnAspiration PneumonianBacterial contamination.48Parenteral Nutrition.49Parenteral NutritionAllows gre

30、ater caloric intakeBUTIs more expensiveHas more complicationsNeeds more technical expertise.50Who will benefit from parenteral nutrition?.51IndicationsPatients with/who nAbnormal Gut functionnCannot consume adequate amounts of nutrients by enteral feedingnAre anticipated to not be abe to eat orally

31、by 5 daysnPrognosis warrants aggressive nutritional support.52Two main forms of parenteral nutritionnPeripheral Parenteral NutritionnCentral (Total) Parenteral NutritionBoth differ in composition of feedprimary caloric sourcepotential complicationsmethods of administration.53Peripheral Parenteral Nu

32、tritionGiven through peripheral veinnshort term use nmildly stressed patientsnlow caloric requirements nneeds large amounts of fluid 1.contraindications to central TPN(total parenteral nutrition).54Total Parenteral NutritionnWhat to do before starting TPN?nNutritional AssessmentnVenous access evalua

33、tionnBaseline weight1.Baseline lab investigations.55Venous Access for TPNNeed venous access to a “large” central line with fast flow to avoid thrombophlebitis.56Steps to administrate TPNnDetermine Total Fluid VolumenDetermine Non-N Caloric needsnDetermine Protein requirementsnDetermine Electrolyte a

34、nd Trace element requirementsnDetermine need for additives.57How much volume to give?nCater for maintenance & on going losses nNormal maintenance requirements nBy body weightnalternatively, 30 to 50 ml/kg/daynAdd on going losses based on I/O chartnConsider insensible fluid losses alsoneg add 10%

35、 for every oC rise in temperature.58Caloric requirementsBased on Total Energy ExpenditurenCan be estimated using predictive equationsTEE = REE + Stress Factor + Activity FactornCan be measured using metabolic cart.59Caloric requirementsStress Factor Malnutrition- 30% peritonitis+ 15% soft tissue tra

36、uma + 15% fracture+ 20% fever (per oC rise) + 13% Moderate infection + 20% Severe infection + 40% 40% BSA Burns+ 100%.60Caloric requirementsActivity FactorBed-bound+ 20%Ambulant + 30% Active + 50%.61Caloric requirementsREE Predictive equationsHarris-Benedict EquationMales: REE = 66 + (13.7W) + (5H)

37、- 6.8AFemales: REE= 655 + (9.6W) + 1.8H - 4.7ASchofield Equation25 to 30 kcal/kg/day.62How much CHO & Fats?“Too much of a good thing causes problems”nNot more than 4 mg / kg / min Dextrose(less than 6 g / kg / day)nNot more than 0.7 mg / kg / min Lipid(less than 1 g / kg / day).63How much CHO &a

38、mp; Fats?nFats usually form 25 to 30% of caloriesnNot more than 40 to 50%nIncrease usually in severe stressnAim for serum TG levels 350 mg/dl or 3.95 mmol / lnCHO(carbohydrate) usually form 70-75 % of calories.64How much protein to give?nBased on calorie : nitrogen rationBased on degree of stress &a

39、mp; body weightnBased on Nitrogen Balance.65Calorie : Nitrogen RationNormal ratio is 150 cal : 1g NitrogennCritically ill patients 85 to 100 cal : 1 g Nitrogen.66Based on Stress & BWnNon-stress patients 0.8 g / kg / daynMild stress 1.0 to 1.2 g / kg / daynModerate stress1.3 to 1.75 g / kg / dayn

40、Severe stress2 to 2.5 g / kg / day.67Electrolyte RequirementsCater for maintenance + replacement needsNa+1 to 2 mmol/kg/d (or 60-120 meq/d)K+0.5 to 1 mmol/kg/d (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.68Trace Elements

41、Total requirements not well establishedCommercial preparations exist to provide RDA(recommended dietary allowance)nZn2-4 mg/daynCr10-15 ug/daynCu0.3 to 0.5 mg/daynMn0.4 to 0.8 mg/day.69TPN MonitoringClinical ReviewLab investigationsAdjust TPN order accordingly.70Clinical Reviewnclinical examinationnvital signsnfluid balancencatheter carensepsis reviewnblood sugar profilenBody weight.71Lab investigationsnFull Blood Count nRenal Panel # 1 nCa+, Mg+, PO42- nLiver Function Test nIron Panel nLipid Panel nNitrogen Balance weekly,