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Nutritional Assessment and Support Clinical Nutrition Outline • Malnutrition - definition - types • Physiology - fasting - starvation - effects of stress & trauma • Nutritional Assessment - presence & degree of malnutrition • Nutritional Support - who benefits proper timing enteral vs. parenteral simple calculations Clinical Nutrition Nutrition • intake of nutrients to provide energy for… - performance of mechanical work maintenance of organ/tissue function heat production maintenance of metabolic homeostasis • TEE (total energy expenditure) - REE or BEE (fasting resting or basal energy expenditure) ~ 70% (~1 kcal/kg/hr) - activity expenditure ~ 20% avg. but very variable - thermic effect of feeding ~ 10% (intake increases the metabolic rate) Clinical Nutrition Malnutrition • estimated that >50% of hospitalized patients exhibit malnutrition • results in the catabolism of energy stores - adipose (oxidation of triglycerides) ~ 13kg in average person - glycogen (glucose) ~ 0.5kg, mostly in muscle - protein (not stored - in use by the body) • skeletal muscle ~ 6-12 kg • other protein stores (organs, visceral proteins, nerve tissue) ~ few hundred grams Clinical Nutrition Types of Malnutrition Marasmus - cachexia chronic calorie malnutrition – relatively balanced diet, but too little for too long usually the result of a longstanding problem (months) see wasting of fat, skeletal muscle (weakness) visceral protein stores less affected Kwashiorkor (West African term – “disease of the displaced child”) - “malnourished African child” (after weaning) with edema and protuberant abdomen more rapid development and worse prognosis chronic protein malnutrition (unbalanced diet) and the presence of physiologic stress fat & skeletal muscle reserves are less depleted (carbohydrates drive insulin) visceral protein stores & immunity are affected early Marasmic kwashiorkor - combined features – usually what is seen in ICU / ill patients malnurished person with stress of illness (hypermetabolic state) worst prognosis – nutritional support tends to only increase fat mass unless the underlying stressors are reversed Clinical Nutrition Early Fasting Human fuel supply (Day One) consumption Liver CNS Circulating glucose glycogen Muscle amino acids glycogen & protein gluconeogenesis lactate pyruvate glycerol Adipose & circulating FFA & TG fatty acids glucose FFA oxidation in mitochondria ketones PNS Medulla Marrow Eyes Muscle Heart Kidney Clinical Nutrition Early Fasting Human fuel supply Muscle 75 g/d (Days 2-14) consumption Liver CNS amino acids glucose gluconeogenesis lactate pyruvate glycerol Adipose fatty acids FFA oxidation in mitochondria * lose 5% body protein stores per week ketones Renal Marrow PNS Eyes Muscle Heart Kidney Clinical Nutrition Adapted Fasting Human fuel supply Muscle 20 g/d (2 to 6 weeks) consumption Liver CNS amino acids glucose gluconeogenesis lactate pyruvate glycerol Adipose fatty acids FFA oxidation in mitochondria ketones Renal Marrow PNS Eyes Muscle Heart Kidney Clinical Nutrition Traumatized Human fuel supply Visceral & Muscle Protein 250 g/d consumption Reparative Process Liver amino acids glycogen CNS glucose gluconeogenesis lactate pyruvate glycerol Adipose fatty acids FFA oxidation in mitochondria ketones Renal Marrow PNS Eyes Muscle Heart Kidney Clinical Nutrition Nutritional Assessment Clinical Nutrition Normal Nutrition Calories - US standard diet for 70kg active man contains ~2700 kcal protein ~325 kcal (81 grams) fat ~1125 kcal (125 grams) carbohydrates ~1250 kcal (312 grams) amount needs to be decreased for inactivity Protein - US standard diet ~80 grams/d (12% of caloric intake) - protein-free diets result in negative nitrogen balance • lose .34 grams protein/kg/d (nitrogen in urine, feces, skin, breath, sputum, etc.) - titrate dietary protein to just keep a positive nitrogen balance • need .38 to .52 grams protein/kg/d (higher estimate b/o inefficiency in utilization) - most use .43 as a minimum and 0.5 - 0.8 gm/kg/d as average - amount needs to be increased for stress (hypercatabolic) Clinical Nutrition Nutritional Assessment • Every patient should prompt three questions - Does pre-existing malnutrition exist? - Is malnutrition likely to occur? - When and how to correct the situation? Clinical Nutrition Does malnutrition exist? • poor intake - weight loss last 6 months (25% false positive, 33% false negative) • <5% considered mild malnutrition; 10% is a useful cut-off in nutritional support decisions • >20% considered severe malnutrition - GI symptoms of anorexia, N/V, diarrhea, malabsorption, obstruction • hypercatabolic pre-admission - infection, sepsis - trauma, burns - major surgery or pulmonary disease • anthropometric changes - loss of SQ fat, muscle wasting, BMI < 18 • functional changes - muscle weakness, respiratory effort, daily activity performance • lab studies - albumin, transferrin, prealbumin, RBP, cholesterol, immune function - affected by by critical illness and become less useful in stressed pts Clinical Nutrition Does malnutrition exist? Subjective Global Assessment Scale (SGA Scale) • graded on 6 features weight change intake GI symptoms functional capacity physiologic stress physical alterations • each feature is rated A = no deficit B = mild deficit C = severe deficit • scored overall A = well nourished = 16% septic complications B = mild to moderate malnutrition = 43% septic complications C = severe malnutrition = 69% septic complications Clinical Nutrition Is Malnutrition Likely to Occur? • poor intake - NPO for more than 5 days - GI symptoms of anorexia, N/V, diarrhea, malabsorption, obstruction • hypercatabolic - infection, sepsis - trauma, burns - major surgery or pulmonary disease Clinical Nutrition Nutritional Support • Theoretical goals of improving the nutritional status of hospitalized patients - improve wound healing decrease infectious complications (in the severely malnourished) decrease non-septic complications decrease ventilator weaning time shorten hospital stays decrease mortality rate Clinical Nutrition Enteral vs Parenteral Nutritional Support • • • • Acute critical illness see catabolism>>anabolism, fat mobilization is impaired. Enteral and parenteral support confer DIFFERENT clinical outcomes in critically ill patients. Enteral nutrition: when started early in the disease (first 48 hrs) may decrease risk of infection compared to delayed initiation (day 8 or >). Barely reaches statistical significance in meta-analyses. Mortality reduction trends lower, but never reaches significance in metaanalyses. Benefit > harm, but positive trials mostly in SICU, not MICU, pts. Parenteral nutrition: no evidence of benefit by early initiation vs late. There is good evidence of harm - 69 trial meta-analysis with 3750 pts comparing early TPN vs none found higher infection rates and no diff in other outcomes or mortality. - 2 studies adding TPN (1 early and 1 late) to enteral nutrition (hyperalimentation) found increased infection rates, days on vent, days in hosp, and mortality in 1 trial. - Head to head studies, mostly SICU (TPN vs enteral): lower infection rate (RR 0.61) and no mortality difference with enteral support. Studies are needed to define roles of each in medical pts (more pre-existing malnutrition) vs surgical (acute illness with less pre-existing malnutrition). Clinical Nutrition Simplified Approach • • • • severe burn or trauma early enteral NS within 24-36 hours severe physiologic stress and diet will be compromised early enteral well-nourished on admit, no hurry malnourished (remember wt loss, BMI <18.5, alb < 3.2, TLC < 1500 can be from catabolism) use decision chart days before tube feeding days before TPN no malnutrition and no stress 7-10 ? (>10-14) malnourished only 1-7 ? (>7) stressed only (critically-ill) 2-3 ? (>10, never) both 1-3 ? (>10, never) patient status Clinical Nutrition Nutritional Support Clinical Nutrition Route of Administration • Enteral - more physiologic (doesn’t bypass gut mucosa and liver) less complicated (supplements, NG tube, PEG, DHT, naso-jejunal tube) less costly (especially cyclic, intermittent, or bolus feeding) fewer infectious and other complications better at preserving gut mucosal integrity and preventing microbial translocation • Parenteral - use only if you cannot use the gut • • • • • • bowel leak (not just bowel surgery; enteral feeding may help fresh anastomosis) bowel obstruction prolonged ileus short bowel / severe malabsorption mesenteric ischemia no gut access Clinical Nutrition Estimate Needs (weight based) • If malnourished (BMI <18.5), use actual body weight to avoid refeeding syndrome • Devine formula, 1974 - males IBW = 50 kg + 2.3 kg for each inch over 5 feet - females IBW = 45.5 kg + 2.3 kg for each inch over 5 feet - • underestimates IBW for short women Robinson formula, 1983 - males IBW = 52 kg + 1.9 kg for each inch over 5 feet - females IBW = 49 kg + 1.7 kg for each inch over 5 feet - • better estimate for females Obesity correction (BMI ≥ 30) - adjusted IBW = IBW + (ABW - IBW)/4 for pts with BMI between 18.5 and 29, most use ABW – edema weight Clinical Nutrition Estimate Needs calories - basal or resting energy expenditure (BEE or REE) men: 66 + (13.7 x kg wt) + (5 x cm ht) – (6.8 x age) or 879 + (10.2 x kg wt) women: 665 + (9.6 x kg wt) + (1.7 x cm ht) – (4.7 x age) or 795 + (7.18 x kg wt) - activity factor bed rest: +5-10% light activity: +50% ambulatory: +20-30% moderate activity: +75% - stress factor minor surgery: +10% appendicitis, long bone fracture: +20% major infection: +30-40% multiple trauma: +60% burns: +30-70% - special cases (unstable sepsis, hypotension) reduce or hold caloric support to avoid hyperglycemia (<110, NEJM 2001) and immune suppression protein - basal 0.5 - 0.8 gm/kg/d - adjust for stress/illness Clinical Nutrition Estimate Needs (Practical Method) • calories per kg/day critically ill: bed rest/mod ill: mild stress or activity: for weight gain: burn patient: 15-20 (18) 25 30 35 40 80 kg patient 2400 kcal 100 grams protein • protein grams per kg/day no stress: mild stress: dialysis moderate stress: severe stress: burn patient: 0.8 1.0 1.3 1.2 1.5 2.0+ Clinical Nutrition TPN Calculations carbo=D70 lipid=F20 protein=AA10 protein=4 kcal/gram AA10=10 grams/dl AA10 =40 kcal/dl AA10 =0.4 kcal/cc 80 kg patient 2400 kcal 100 grams protein protein 100x4=400 kcal 480/0.4=1000 cc 2400-400=2000 kcal fat=9 kcal/gram F20=20 grams/dl F20=180 kcal/dl F20=1.8 kcal/cc dextrose=3.45 kcal/gram D70=70 grams/dl D70=241 kcal/dl D70=2.4 kcal/cc lipid 2400x30%=720 kcal 720/1.8=400 cc 2000-720=1280 kcal carbo 1280/2.4=530 cc *propofol is ~F10 = 1 kcal/cc Clinical Nutrition Monitoring Nutritional Status/Support • • • • • correct osmolality, volume, glucose and electrolyte abnormalities first watch for refeeding syndrome (fluid retention/CHF, low phos, K, Mg, high glucose) if serum glucose is hard to control, increase lipid ratio (up to 50-66% of calories), but remember that lipid is less nitrogen preserving than dextrose (below 150 g/d dextrose) if triglycerides are hard to control, lower the lipid ratio (can be removed for periods) follow weights daily, consider prealbumin weekly, and UUN occasionally (rare) N balance = (grams protein intake/6.25) - (grams UUN + 4) grams N deficit x 6.25 = extra grams protein needed albumin rise prealbumin rise transferrin rise sensitivity 61% 88% 67% specificity 41% 70% 55% PPV 86% 93% 87% NPV 17% 56% 27%