Nutritional Assessment and Support

Nutritional Assessmentand

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 MalnutritionMarasmus

- 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

Adipose&

circulatingFFA & TG

amino acids

glycerol

fatty acids

Liver

gluconeogenesis

Early Fasting Human(Day One)

FFA oxidationin mitochondria

ketones

glucose

CNS

MuscleHeart

Kidney

lactatepyruvate

glycogen

fuelsupply

consumption

PNSMedulla Marrow

Eyes

Circulatingglucose

Muscle glycogen & protein

Clinical Nutrition

Adipose

amino acids

glycerol

fatty acids

Liver

gluconeogenesis

Early Fasting Human(Days 2-14)

FFA oxidationin mitochondria

ketones

glucose

CNS

MuscleHeart

Kidney

lactatepyruvate

fuelsupply

consumption

* lose 5% body protein stores per week

Renal Marrow

PNSEyes

Muscle75 g/d

Clinical Nutrition

Adipose

amino acids

glycerol

fatty acids

Liver

gluconeogenesis

Adapted Fasting Human(2 to 6 weeks)

FFA oxidation in mitochondria

ketones

glucose

CNS

MuscleHeart

Kidney

lactatepyruvate

fuelsupply

consumption

Muscle20 g/d

Renal Marrow

PNSEyes

Clinical Nutrition

Adipose

amino acids

glycerol

fatty acids

Liver

gluconeogenesis

Traumatized Human

FFA oxidation in mitochondria

ketones

glucose

CNS

MuscleHeart

Kidney

lactatepyruvate

glycogen

fuelsupply

consumption

ReparativeProcess

Renal Marrow

PNSEyes

Visceral& MuscleProtein250 g/d

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 featuresweight changeintakeGI symptomsfunctional capacityphysiologic stressphysical alterations

• each feature is ratedA = no deficitB = mild deficitC = severe deficit

• scored overallA = well nourished = 16% septic complicationsB = mild to moderate malnutrition = 43% septic complicationsC = 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 meta-analyses. 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

patient statusdays beforetube feeding

days beforeTPN

no malnutritionand no stress

7-10 ? (>10-14)

malnourished only 1-7 ? (>7)

stressed only (critically-ill) 2-3 ? (>10, never)

both 1-3 ? (>10, never)

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 useABW – edema weight

Clinical Nutrition

Estimate Needscalories

- 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 factorbed rest: +5-10% light activity: +50%ambulatory: +20-30% moderate activity: +75%- stress factorminor 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- basal0.5 - 0.8 gm/kg/d- adjust for stress/illness

Clinical Nutrition

Estimate Needs(Practical Method)

• calories per kg/daycritically ill: 15-20 (18)bed rest/mod ill: 25mild stress or activity: 30for weight gain: 35burn patient: 40

• protein grams per kg/dayno stress: 0.8mild stress: 1.0dialysis 1.3moderate stress: 1.2severe stress: 1.5burn patient: 2.0+

80 kg patient

2400 kcal

100 grams protein

Clinical Nutrition

TPN Calculations

dextrose=3.45 kcal/gramD70=70 grams/dlD70=241 kcal/dlD70=2.4 kcal/cc

carbo=D70

lipid=F20

protein=AA10

fat=9 kcal/gramF20=20 grams/dlF20=180 kcal/dlF20=1.8 kcal/cc

protein=4 kcal/gramAA10=10 grams/dlAA10 =40 kcal/dlAA10 =0.4 kcal/cc

80 kg patient2400 kcal

100 grams protein

protein100x4=400 kcal480/0.4=1000 cc

lipid2400x30%=720 kcal

720/1.8=400 cc

2400-400=2000 kcal

2000-720=1280 kcal

carbo1280/2.4=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%