Surgical Foundations – Sep 7, 2011

Surgical Foundations – Sep 7, 2011
Dr. Alfonse Marchie
Dr. Natasha Cohen
Dr. Shezad Tejani
Dr. Tiffaney Kittmer
Guest Expert: Michele ApSimon, MSc, RD
Nutritional Requirements
Adaptation to Stress
Nutritional Support
"One man’s food is
another man’s poison."
 Roman healer and philosopher
Lucretius- 55 BC
 Metabolism is the body's biochemical anabolic (creating or
synthesizing) and catabolic (breaking down) reactions
 Rate at which one burns calories
 Basal metabolic rate (BMR)- rate your body burns calories
in a rested state
 Average adult’s BMR about 1,200 to 1,800 calories per day
Factors that affect Metabolic
Gender, race, age
Calculating the BMR
 Male= 66.5 + (13.8 x BW in Kg) + (5 x height in cm) (6.8
x age)
 Female= 65.5 + (9.6 x BW in Kg) + (1.7 x height in cm)
(4.7 x age)
 100 patients admitted to surgical ward
 Malnutrition Universal Screening Tool (MUST)
 33% had high scores-high malnutrition risk
 Longer hospital stay (19 days vs. 5 days)
 Mortality higher
Populations at Risk for
Cancer receiving chemotherapy
Major trauma, burn injuries
Inflammatory bowel disease
Chronic renal failure
Chronic neurological disorders
Fever, sepsis
Clinical Sequelae of Impaired
Inability to handle excess salt/water intake
Bowel edema inhibits GI function
Wound edema inhibits healing
Prevents normal cardiovascular response to shock
Clinical Sequelae of Impaired
 Muscle wasting
 Impairs ventilating capacity and susceptibility to
ventilatory failure and chest infection
 Impaired cell mediated immunity
 Susceptibility to infection
Nutritional assessment
Clinical (history and physical examination)
Biochemical tests
Body composition
 Anorexia, nausea, and vomiting
 Chronic or recent weight loss
 Unintentional weight loss = ↑ complications
Preoperative unintended weight
loss and low body mass index in
relation to complications and
length of stay after cardiac
 Lenny MW van Venrooij, Rien de Vos, Mieke MMJ
Borgmeijer-Hoelen, Cees Haaring, and Bas AJM de Mol
 Preoperative unintended weight loss (UWL) in cardiac
surgery patients
 Examined 330 patients
 Preoperative UWL of ≥10% in the past 6 mo associated
with a prolonged length of stay
 Preoperative BMI ≤ 21.0 was associated with increased
incidence of postoperative infections & prolonged stay in
the intensive care unit
<10% - mild malnutrition, over 1 month
10-20%- moderate malnutrition, over 1 month
>20% - severe, in 6 months
>30% - pre-morbid
>50% - pre-mortality
Physical Exam
 Weight and height
 Hair loss, skin breakdown, peripheral edema, and muscle
 Muscle strength
 Frontal-occipital head circumference (FOC)
 Triceps skin-fold (TSF) thickness
 Mid-arm circumference (MAC)
Biochemical Tests
Albumin (T1/2 = 21days)
Retinol-binding protein
Delayed Cutaneous Hypersensitivity (DH)
Prognostic Nutritional Index
 PNI%= 158- 16.6(albumin) – 0.78(TSF) – 0.2(TFN) –
 TSF= Triceps skin fold thickness in mm
 TFN= Transferrin
 DH = Delayed hypersensitivity (may be substituted with lymphocyte score)
Prognostic Inflammatory
Nutrition Index (PINI)
where CRP= C-reactive protein, AAG= alpha 1-acidglycoprotein, PA= pre-albumin, ALB=albumin
 Energy is required continuously for normal
 organ function
 maintenance of metabolic homeostasis
 heat production
 performance of mechanical work
Estimated Energy
•Dietary energy intake that is predicted to maintain energy
balance in a healthy individual.
– In children, it includes the needs associated with growth. For
most healthy infants and children, the equations here can be used
to determine energy needs.
– ~1 kcal/kg/hour
•a. For infants, children, and adolescents, EER (kcal/day) = TEE
+ energy deposition (required for growth)
•b. For most hospitalized patients, it can be assumed
PAL = sedentary, PA = 1
Health Canada
• Adults
– EER(kcal/day) = Total Energy
– Men
EER = 662 - (9.53 x age [y]) + PA
x { (15.91 x weight [kg]) + (539.6
x height [m]) }
EER = 354 - (6.91 x age [y]) + PA
x { (9.36 x weight [kg]) + (726 x
height [m]) }
» PA = physical activity
Resting energy expenditure
• Def: Amount of energy (calories) required for 24h for a
non-active period
• Liver, intestine, brain, kidneys, and heart
– 10% of total body weight
– account for approximately 75% of REE.
• Skeletal muscle at rest
– 40% of body weight
– approximately 20% of REE
• Adipose tissue
– more than 20% of body weight
– consumes less than 5% of REE
Indirect calorimetry
 Resting energy expenditure (REE), respiratory quotient
(RQ) and substrate utilization will be calculated from
measurements of oxygen (VO2) and carbon dioxide
(VCO2) in inspired and expired air
 Respiratory quotient:
 RQ = VCO2 / VO2
Respiratory quotient
 An RQ may rise above 1.0 for an organism burning
carbohydrate to produce or "lay down" fat (for example, a
bear preparing for hibernation)
 RQ value corresponds to a caloric value for each liter (L)
of CO2 produced
 Total daily energy expenditure (TEE)
 resting energy expenditure (~70% of TEE)
 expenditure of physical activity (~20% of TEE)
 thermic effect of feeding (~10% of TEE),
temporary increase in energy expenditure that accompanies
enteral ingestion or parenteral administration of nutrients
Metabolic stress
• TEE = REE X stress factor
• In acutely ill hospitalized patients, it is usually not
necessary to include an activity factor
Energy in Metabolic Stress
 An alternative and rather simple formula for adult
 20-25 kcal/kg of actual body weight (ABW)/day for
unstressed or mild stress
 25-30 kcal/ABW/day for moderate stress
 30-35 kcal/ABW/day for severe stress
 ABW can be misleading (lean body mass) if
>30% of ideal body weight (IBW)
 Adjusted IBW = IBW+ 0.33(ABW− IBW)
 20 amino acids are found commonly in human
 Essential amino acids cannot be synthesized by
the body
histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, threonine, tryptophan, valine, and possibly
 Non-essential amino acids – can be made
glycine, alanine, serine, cysteine, cystine, tyrosine,
glutamine, glutamic acid, asparagine, and aspartic acid
 The U.S. Recommended Daily Allowance
(RDA) of protein is 0.8 g/kg/day
Protein in Health
• The body of an average 75-kg man contains approximately 12 kg of protein.
• In contrast to fat and carbohydrate, there is no storage for protein
• excess intake is catabolized and the nitrogen component is excreted
• As metabolic stress/rate increases, nitrogen excretion increases proportionately
• 2 mg nitrogen (N)/kcal of REE
Protein in illness
• Nonessential amino acids may become essential
– Termed: conditionally essential amino acids
– wound healing appear to be improved in critically ill
patients by the inclusion of supplemental glutamine in total
parenteral nutrition (TPN) because of cellular depletion of
this amino acid.
– parenteral glutamine has benefits in patients with
particularly high severity of illness scores (e.g., high
APACHE II or SOFA scores)
– Similarly, it cysteine and tyrosine are essential in with
cirrhosis because of impaired hepatic synthesis
Normal man has 280g.
Turnover is 9-12g daily.
Half life is 15-28 days.
Pre-Albumin half life is 2 days - correlates better with
nutritional status.
 Albumin falls in stress because liver switches to
producing acute phase proteins such as CRP and ferritin.
Nitrogen Balance
 Proxy for protein balance
 N balance = grams of N administered as nutrition –
(urinary urea N[g] + 4)
 6.26g of protein = 1g of Nitrogen
 Principal dietary digestible:
Starch, sucrose and lactose
 no absolute dietary requirement for carbohydrate
 glucose can be synthesized from endogenous amino acids as
well as glycerol
 5 to 20 g of indigestible carbohydrate (soluble and
insoluble fibers) are consumed daily.
 Carbohydrate intake stimulates insulin secretion
inhibits muscle protein breakdown
stimulates muscle protein synthesis
decreases endogenous glucose production from amino acids
 glucose is the required fuel for:
red and white blood cells
renal medulla
eye tissues
peripheral nerves
glucose requirements for these tissues are met ( 150 g/day)
• Triglycerides (TGs), sterols, and
• Serve as:
– sources of energy
– precursors for steroid hormone, prostaglandin,
thromboxane, and leukotriene synthesis
– structural components of cell membranes
– carriers of essential nutrients
• Dietary lipids are composed mainly
of TGs, which contain saturated and
unsaturated long-chain fatty acids (FAs) of
16 to 18 carbons.
• The use of fat as a fuel requires the hydrolysis of
endogenous or exogenous TGs and cellular uptake of
released Fatty Acids
• Long-chain FAs are transferred across mitochondrial
membranes by a carnitine dependent transport system.
• Once inside the mitochondria, FAs are degraded by beta
oxidation to acetyl coenzyme A (CoA), which then
enters the TCA cycle.
• A decrease in the number of mitochondria or oxidative enzymes
associated with aging or deconditioning favors the use of
carbohydrate as fuel.
Essential fatty acids
 Humans lack the desaturase enzyme
needed to produce the n-3 (double bond between carbons 3 and 4)
and n-6 (double bond between carbons 6 and 7) FA series.
 Linoleic acid (C18 : 2, n-6) and linolenic acid (C18 : 3, n3), therefore, should constitute at least 2% and 0.5%,
respectively, of the daily caloric intake to prevent essential
FA deficiency (EFAD).
EFAD & Risk factors
 Essential FA stores in adipose tissue
 Thought to be protective for essential fatty acid deficiency
 However…
 abnormal FA profile in conjunction with a clinical syndrome
of EFAD is now known to occur sometimes in adults with
severe short bowel syndrome who are on long-term total
parenteral nutrition (TPN) that lacks parenteral lipids
Major Minerals
 Definition:
Inorganic nutrients that are required in large quantities
 important for ionic equilibrium, water balance, and normal
cell function.
 Malnutrition and nutritional repletion can have dramatic
effects on major mineral balance.
• Vitamins and trace minerals
• Used as coenzymes, prosthetic groups, biochemical,
substrates or hormones
 Fat soluble
 Do not serve as co-enzymes
 Absorption through micelles
 Water soluble
 Co-enzymes
Trace elements
 Evidence exists that there are 10 essential nutrients in
 Iron, Zinc, Copper, Chromium, Selenium, Iodine,
Fluorine, Manganese, Molyndenum and Cobalt
 Iron most commonly deficient, then zinc
Chronic GI issues (s.a. IBD) known to precipitate zinc deficiency
Vitamin A
Vitamin D, E
Vitamin K
Trace Minerals
Trace Minerals
 Impaired Nutrition
 Nosocomial infections
 Longer Hospital stay
 Impaired Wound Healing
 Loss of Muscle Function and Wasting
 Ventilatory Performance and Dependence
 Rationale for Effective use of Nutritional therapy
 Dynamics of metabolic response to challenge:
Starvation Vs. Surgical Stress
Adaptations to Food Deprivation
Short-Term Fasting
Insulin and Glucagon  Hepatic Glycogenolysis
(100g) for glucose mainteinance
 Fat  Bulk of calories, releasing free fatty acids and
 Protein Mobilization  Amino Acids
 Normal Turnover: 2.5% to 3%
 300g of protein / day Initially
 Decreased Protein synthesis and Increased Degradation
Short-Term Fasting
 Peripheral Tissues: FFA and Ketone Bodies Utilization for
ATP and Inhibition of Glucose Utilization
 BCAA Oxidation in Muscle
 Glycogen reserves exhausted within 48 hrs.
 Gluconeogenesis in the Liver and Kidney via Glutamine,
Alanine, Lactate and Glycerol
 Maintenance of Blood Glucose for Brain, Erythrocytes and
Long-Term Fasting
 Initially: 75g of muscle protein = 300g of muscle per day
mobilized for gluconeogenesis
 If continues  1/3rd of total body protein exhausted in 3 wks
 Long Term Starvation: Major Metabolic Adaptation  CNS
switches fuels to ketone bodies
 Shift from Protein source to Fats (Ketones)
 Protein Sparing and Preserving Functional Role.
 Obligatory Proteolysis  20 g protein /d
 1 Wk of Starvation  Diminished AV difference in AA and by
decreased urinary N-methylhistidine excretion
Endocrine / Metabolic Response
to Surgery
 The “Stress” Response
 Neuroendocrine: Sympathetic Nervous System
 Endocrine : HPA System
 Inflammatory: Cytokines
 Substrate Mobilization  Energy
 Salt and Volume Retention
Response To Surgery
Two Phases
Ebb Phase
 Transitory over 24 hrs
 Depression of body`s physiological
Blood Flow, Temp and Oxygen
Rise of Stress hormones
Accumulation of Water, proteins and Na at
site of injury
Flow Phase
 Hypermetabolic State
 Catabolic Phase
Increased Loss of Nitrogen and other body
Sympathetic Response
 Catecholamines / NE – Presynaptic nerve terminals and
Adrenal Medulla
 Tachycardia and HTN
 Renin - Ang I  Ang II  Aldosterone Na
 Glucagon - Glycogen breakdown and FFA mobilization
 Pituitary
 ACTH and GH
 Vasopressin
 Cortisol
 above 1500 nmol / L within 4-6hrs of major surgery. Levels
related to severity of insult.
 Skeletal muscle protein breakdown
 Lipolysis
 Mineralocorticoid Effects
 Growth Hormone
 Glycogenolysis and Lipolysis
 Glucose uptake and utilization inhibited
 Role in reducing protein catabolism
 Insulin
 Release inhibited through inhibition of B-cells by alphaadrenergic inhibitory effects of catecholamines.
 Insulin Resistance state
 Thyroid
 T4 and T3 -- Oxygen consumption and increased metabolic rate
and heat production
Substrate Mobilization
Carbohydrate Metabolism
 Hyperglycemia – Catecholamines and Cortisol
 Regulation of glucose via Insulin ineffective due to initial insulin
inhibition and resistance.
 High glucose state – impair wound healing and infections
Lipid Metabolism
 High Catecholamines, Cortisol and Glucagon and low Insulin
promote lipolysis and ketone production.
 FFA – Acyl CoA – Ketone in liver
Substrate Mobilization
 Net Protein Catabolism
Inhibition of protein anabolism
Enhanced Catabolism via Cortisol and Cytokines
Increased Amino Acid turnover – negative Nitrogen balance.
Proteolysis increase over 45% (600 to 800g of muscle loss per
Protein Degradation co-relates with type of surgery and
Nutritional status
Skeletal muscle followed by Visceral muscle
Functional Compromise
Metabolic Response To
Severity of Trauma: Effects on
Nitrogen Losses and Metabolic
Protein Catabolism:
Starvation Vs. Surgery
 Muscle, Free AA and all body proteins involved in
catabolic state including Serum proteins
 Albumin, Prealbumin and Transferrin
 Serum protein concentrations fall more rapidly in and to
greater extent with starvation following surgery than with
starvation alone
 Surgical Stress – accelerates breakdown of proteins and
increases turnover in setting of limited substrates.
Starvation Vs. Surgery
Starvation vs. Surgery
 Both present a nutritional and metabolic challenge
 Similar processes initiated
In Starvation: Metabolic Adaptation resulting in reduction of
energy expenditure of up to 40% and limitation of proteolysis
from 75g to 20g per day
Post-op / Trauma: These mechanisms limiting proteolysis are
either impaired or non-operative
net Nitrogen loss
Nutritional Support
Indications for Nutritional
Poor nutritional status (oral intake <50% of energy needs)
Catabolic disease (burns, sepsis, pancreatitis)
Significant weight loss (>10%)
Anticipated need for more than 7 days of nutritional
 Non-functioning gastrointestinal tract
 Albumin <30 g/L in the absence of an inflammatory state
 Enteral
 Oral
 Naso-gastric/duodenal/jejunal
 Orogastric
 Gastric/gastrojejunal
 Jejunal
 Parenteral
 Central line
 Peripheral intravenous
Enteral Feeds
 “If the gut works, use it!”
 Avoids complications of venous catheters
 Mimics normal flow of nutrients from GI
tract to liver, likely beneficial to hepatic
 May improve immune function
Mechanism suspected to be related to IgA
 May promote maintenance of GI
mucosa’s integrity
has been shown in burns and hemorrhagic
Enteral Feeds
 Cheap, easy, effective
 With large-calibre tubes can check residuals
 Generally check q4h
 Goal: residuals <150ml
 Many of the tubes traverse the GE junction
 GERD, aspiration are resultant problems, no matter where
the end of those tubes are sitting
 Absolute contraindications
 Bowel ischemia, perforation, peritonitis, mechanical
Parenteral Feeds
 Peripheral
 Only safe for short-term (4-7 days)
 Glucose concentration limited to max 5%
 Better than nothing, but usually can’t meet a
sick patient’s full nutritional requirements
via this route
 Central
 I.e. Tip of catheter in the SVC
 Can be used for longer term TPN
 Higher concentrations
Choose the route!
 78 F with dysphagia from an ischemic stroke with good
rehab potential vs with poor rehab potential
 55 M with generalized peritonitis from perforated cecal
volvulus presenting one day later in severe septic shock,
stay complicated by leak on POD2 from his right
 24 M with mild pancreatitis vs in ICU with severe
 74 F multi-trauma, intubated in ICU and awaiting
definitive repair of her R femur # in about 1 week
TPN Content
 2-in-1: amino acids and dextrose
 3-in-1: amino acids, dextrose and lipids (much more
 Common additions:
TPN Math
 Goal: 25-35 kcal/kg/day
 Lipids: 20% of caloric intake (omit if doing a 2 in 1 mix)
 Protein: 1.5 g/kg/day
 Carbohydrates: the remainder to reach caloric intake
 Reference values
 Glucose: 3.4 kcal/g
 Protein: 4 kcal/g
 Lipids: 9 kcal/g
TPN Calculation Case
 67 year-old 80kg male with severe radiation enteritis.
 1) Total caloric requirement (25-35 kcal/kg/day)
 2) Daily protein requirement (1.5g/kg/day)
 3) Lipid component (20% of calories)
 4) Use dextrose for the rest of needed calories
 5) Check maximums
Max Carb: 5g/kg/day
Max Protein: 2g/kg/day
Max Lipids: 2.5g/kg/day
Caloric Content
Glucose: 3.4 kcal/g
Protein: 4 kcal/g
Lipids: 9 kcal/g
TPN Calculation Answers
 1) Total caloric requirement (25-35 kcal/kg/day)
 30kcal/kg/day X 80kg = 2400 kcal/day
 2) Daily protein requirement (1.5g/kg/day)
 1.5g/kg/day X 80kg = 120g/day
 120g X 4kcal/g = 480 kcal
 3) Lipid component (20% of calories)
 2400 X 0.2 = 480 kcal
 480 kcal / 9 kcal/g = 53.3 g
 4) Use dextrose for the rest of needed calories
 Total – protein – fat = 2400 – 480 – 480 = 1440 kcal
 1440 kcal / 3.4 kcal/g = 424 g
 Put it all together: 120g of protein, 53g of lipids, 424g of dextrose
 5) Check maximums
 Max Carb: 5g/kg/day = 400g (24g over)
 Max Protein: 2g/kg/day = 160g (ok)
 Max Lipids: 2.5g/kg/day = 200g (well under)
TPN Monitoring
 Clinical
 Weights, signs of infection
 Bloodwork
 CBS q6h
 Baseline and daily until stable: lytes, ext lytes, BUN, Cr,
 Baseline and weekly: LFTs, albumin, TGs, INR
TPN Risks
 Catheter
 Line infection
More lumens = higher infection risk (triple vs single lumen)
PICC = higher incidence of leakage, malpositioning,
thrombophlebitis compared to central lines, same rates of sepsis
Hyperglycemia increases incidence of infection
80% of infections are Staph aureus/epidermidis
TPN Risks
Line thrombosis
 Line placement
Thoracic duct injury
Arterial/venous injuries
Air embolus
Catheter embolus
Chronic pain
Brachial plexus injury
Erosion of catheter into
nearby structures
TPN Risks Cont’d
 Liver dysfunction: cholestasis, steatosis, cirrhosis
 Full mechanism still being elucidated
?inflammation-mediated hepatocellular damage
?lack of hormone activation
?glucagon/insulin imbalance resulting in lipogenesis
 Decreased bone mineral density
 Feeds enriched in nutrients (such as arginine, omega-3 fatty
acids & nucleotides) to modulate host immunity
 Literature to support this not strong
 Daly et al 1992 – post-op immunonutrition vs standard nutrition
Problem: control group formula isocaloric, but less protein
 Braga et al 1995 – pre- and post-op immunonutrition vs standard
Problem: results not replicated in subsequent studies
 Both above studies and meta-analyses show trends toward
reduced infection rates and decreased length of stay in tx groups,
but cannot fully attribute this to the additives due to study design
issues and data heterogeneity
 The debate continues
 Sabiston Textbook of Surgery – Chapter 7
 Cecil Medicine – Chapters 220-225
 Michele ApSimon
[email protected]