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1、1,Surgical Metabolism and Nutrition,Dr.Ouyang Jun,MD,PhDthe 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 proble
2、ms in surgical diseasesIncluding enteral and parenteral nutrition,Enteral nutrition,Use of an intact gastrointestinal tract for nutritional supportBenefits:physiologic;immunologic;saffety;cost;,Indications for enteral feeding,Malnourished patients who have an intact gastrointratinal tract should ini
3、tially 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:peripheral Parenteral nutriti
4、on and total Parenteral nutrition,l,8,Benefits of Nutritional Support,Preservation of nutritional statusPrevention of complications of protein malnutrition Post-operative complications,9,Nutritional support,along with antibiotics,blood transfusion,critical care monitoring,advances in anesthesia,orga
5、n 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 which enteral support cannot be ac
6、hievedeither 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 Calories can come from glucose or fat.The
7、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 protein is related to its amino acid composi
8、tion.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 body is able to synthesize fats from other dietary
9、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 metabolism,wound healing,and immune function.,15,Trace Eleme
10、nts,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 patientsMalnutrition can lead to increased post-operative morbidi
11、ty and mortalityImpairment of skeletal,cardiac,respiratory muscle functionImpairment of immune functionAtrophy of GITImpaired healing,17,Nutritional Pathophysiology,18,Pathophysiology,Proteins and amino acidsRequire daily intake 0.8 g kg-1 ie.56 g for a 70 kg personEssential:a.a only obtained by die
12、tary sourceNon-essential:can be endogenously synthesisedconditionally essential:a.a unable to be synthesised under certain conditions eg.Stress,surgeryL-alanine,L-glutamate,L-asparate,19,Pathophysiology,Nutritional Balance=N input-N output1 g N=6.25 g proteinN input=(protein in g/6.25)N output=24h u
13、rinary urea nitrogen+non-urinary N losses(estimated normal non-urinary Nitrogen losses about 3-4g/d),20,Fatty acidsShort,medium chain FA directly enter portal systemLong chain FA transported as triglyceridesEssential FA unable to be synthesised ie.Linoleic and linolenic acid.Deficiency causes skin,k
14、idney disorders,Pathophysiology,21,Pathophysiology,Energy requirements:Total daily expenditure 25-30 kcal kg-1Resting metabolic rateActivity energy expenditureDiet induced energy expenditureSources:Fats9 kcal g-1Protein4 kcal g-1Carbohydrates4 kcal g-1Alcohol 7 kcal g-1,22,Patho-physiology,Energy re
15、quirements:BMR calculated by Harris-Benedict equation66.47+13.75 x W+5 x H 6.76xAAdditional caloric needs calculated by an injury factor,eg.Minor operation 1.2 x BMRTrauma1.3 x BMRSepsis 1.6 x BMRBurns2.1 x BMR,23,Pathophysiology,VitaminsKey metabolic rolesFat soluable(A,D,E,K)or water soluable,24,P
16、athophysiology,Trace elementsZinc wound healing,protein and nucleic acid synthesisFe energy transferCopper collagen synthesisSelenium anti-oxidant enzyme system,25,Pathophysiology,Changes in Starvation:decrease energy expenditure,liver glycogen depletion in 24hhepatic and muscle gluconeogenesis depl
17、eted after 24hlater consume fat,26,Pathophysiology,Changes in trauma and sepsisCatabolic phaseIncrease resting energy expenditureLoss of body nitrogen,muscle breakdownIncrease glucose production(glycogenolysis),deplete liver storesIncrease lipolysisEarly anabolic phaseLate anabolic phase,27,Who requ
18、ires nutritional support?,Patients already with malnutrition-surgery/trauma/sepsisPatients at risk of malnutritionSurgical patients who 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 malnu
19、trition,Depleted reservesCannot eat for 5 daysImpaired bowel functionCritical Illness Need for prolonged bowel rest,29,How do we detect malnutrition?,30,Nutritional Assessment,History Physical examinationAnthropometric measurementsLaboratory investigations,31,History,Dietary historySignificant weigh
20、t loss within last 6 months 15%loss of body weightcompare with ideal weightBeware the patient with ascites/oedema,32,History and physical examination,The nutritional assessment is based on information from the history and physical examination.A complete medical history is essential to identify facto
21、rs that predispose the patient to an altered nutritional status.,33,Physical Examination,A careful physical examination begins with an overall assessment of the patients appearance.Evidence of muscle wastingDepletion of subcutaneous fatPeripheral oedema,ascitesFeatures of Vitamin deficiencyeg nail a
22、nd mucosal changesEchymosis and easy bruisingEasy to detect 15%loss,34,Anthropometric Measurements,Anthropometry is 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 fo
23、r Height comparisonBody Mass Index(10%decrease)Triceps-skinfold Mid arm muscle circumferenceBioelectric impedanceHand grip dynamometryUrinary creatinine/height index,36,Laboratory Data,The visceral protein reserve is estimated from the serum total protein,albumin,and transferrin levels;total lymphoc
24、yte count;and antigen skin testing.,37,Determining Energy Requirements,The adult daily caloric 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/dlpre-albumin 12 mg/dltransferrin 150 m
25、mol/ltotal lymphocyte count 1800/mm3tests reflecting specific nutritional deficitseg Prothrombin timeSkin anergy testing,39,How can we administrate nutritional support?,40,Nutritional Support,Types Enteral NutritionParenteral Nutrition,41,Enteral Feeding is best,Enteral nutrition(EN):use of intact g
26、astrointestinal tract for nutritional supportBenefits:Physiologic&MetabolicImmunologicSafetyCost,42,Indications of Enteral Feeding,When nutritional suport is neededFunctioning gut presentNo contra-indicationsno ileusno recent anastomosis of gutno fistula,43,What can we give in tube feeding?,Blenderi
27、sed feedsCommercially prepared feeds Polymeric eg Isocal,Ensure,JevityMonomeric/elemental eg Vivonex,44,Complications of enteral feeding,12%overall complication rateGastrointestinal complicationsMechanical complicationsMetabolic complicationsInfectious complications,45,Complications of enteral feedi
28、ng,GastrointestinalDistensionNausea and vomiting DiarrhoeaConstipationIntestinal ischaemia,46,Complications of enteral feeding,MechanicalMalposition of feeding tubeSinusitisUlcerations/erosionsBlockage of tubes,47,Complications of enteral feeding,InfectiousAspiration PneumoniaBacterial contamination
29、,48,Parenteral Nutrition,49,Parenteral Nutrition,Allows greater caloric intakeBUTIs more expensiveHas more complicationsNeeds more technical expertise,50,Who will benefit from parenteral nutrition?,51,Indications,Patients with/who Abnormal Gut functionCannot consume adequate amounts of nutrients by
30、enteral feedingAre anticipated to not be abe to eat orally by 5 daysPrognosis warrants aggressive nutritional support,52,Two main forms of parenteral nutrition,Peripheral Parenteral NutritionCentral(Total)Parenteral NutritionBoth differ in,composition of feedprimary caloric sourcepotential complicat
31、ionsmethods of administration,53,Peripheral Parenteral Nutrition,Given through peripheral veinshort term use mildly stressed patientslow caloric requirements needs large amounts of fluid contraindications to central TPN(total parenteral nutrition),54,Total Parenteral Nutrition,What to do before star
32、ting TPN?Nutritional AssessmentVenous access evaluationBaseline weightBaseline lab investigations,55,Venous Access for TPN,Need venous access to a“large”central line with fast flow to avoid thrombophlebitis,Long peripheral linesubclavian approachinternal jugular approachexternal jugular approach,Sup
33、erior Vena Cava,56,Steps to administrate TPN,Determine Total Fluid VolumeDetermine Non-N Caloric needsDetermine Protein requirementsDetermine Electrolyte and Trace element requirementsDetermine need for additives,57,How much volume to give?,Cater for maintenance&on going losses Normal maintenance re
34、quirements By body weightalternatively,30 to 50 ml/kg/dayAdd on going losses based on I/O chartConsider insensible fluid losses alsoeg add 10%for every oC rise in temperature,58,Caloric requirements,Based on Total Energy ExpenditureCan be estimated using predictive equationsTEE=REE+Stress Factor+Act
35、ivity FactorCan 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%Ambulant+30%
36、Active+50%,61,Caloric requirements,REE Predictive equationsHarris-Benedict EquationMales:REE=66+(13.7W)+(5H)-6.8AFemales:REE=655+(9.6W)+1.8H-4.7ASchofield Equation25 to 30 kcal/kg/day,62,How much CHO&Fats?,“Too much of a good thing causes problems”Not more than 4 mg/kg/min Dextrose(less than 6 g/kg/
37、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 caloriesNot more than 40 to 50%Increase usually in severe stressAim for serum TG levels 350 mg/dl or 3.95 mmol/lCHO(carbohydrate)usually form 70-75%of calories,64,How much protein to give?
38、,Based on calorie:nitrogen ratioBased on degree of stress&body weightBased on Nitrogen Balance,65,Calorie:Nitrogen Ratio,Normal ratio is 150 cal:1g NitrogenCritically ill patients 85 to 100 cal:1 g Nitrogen,66,Based on Stress&BW,Non-stress patients0.8 g/kg/dayMild stress 1.0 to 1.2 g/kg/dayModerate
39、stress1.3 to 1.75 g/kg/daySevere stress2 to 2.5 g/kg/day,67,Electrolyte Requirements,Cater 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
40、,68,Trace Elements,Total requirements not well establishedCommercial preparations exist to provide RDA(recommended dietary allowance)Zn2-4 mg/dayCr10-15 ug/dayCu0.3 to 0.5 mg/dayMn0.4 to 0.8 mg/day,69,TPN Monitoring,Clinical ReviewLab investigationsAdjust TPN order accordingly,70,Clinical Review,cli
41、nical examinationvital signsfluid balancecatheter caresepsis reviewblood sugar profileBody weight,71,Lab investigations,Full Blood Count Renal Panel#1 Ca+,Mg+,PO42-Liver Function Test Iron Panel Lipid Panel Nitrogen Balance,weekly,unless indicateddaily until stable,then 2x/wkdaily until stable,then
42、2x/wkweeklyweekly1-2x/wkweekly,72,Complications related to TPN,Mechanical ComplicationsMetabolic ComplicationsInfectious Complications,73,Mechanical Complications,pneumothoraxair embolismarterial injurybleeding,brachial plexus injurycatheter malplacementcatheter embolismthoracic duct injury,Related
43、to vascular access technique,74,Infectious Complications,Insertion site contaminationCatheter contaminationimproper insertion techniqueuse of catheter for non-feeding purposescontaminated TPN solution contaminated tubingSecondary contaminationsepticaemia,75,Metabolic Complications,Abnormalities rela
44、ted to excessive or inadequate administrationhyper/hypoglycaemiaelectrolyte abnormalitiesacid-base disordershyperlipidaemia,76,Metabolic Complications,Hepatic complicationsBiochemical abnormalitiesCholestatic jaundicetoo much calories(carbohydrate intake)too much fatAcalculous cholecystitis,77,How to select route of nutrition support in clinical decision?,78,79,Thank you!,
