Nutrition Clinical Flashcards
What is malnutrition?
A deficiency or excess (imbalance) of energy, protein and other nutrients that causes measurable adverse effects on the tissue/ body size etc and clinical outcome
What abnormal nutrient intake deficiencies is malnutrition associated with?
Nutrient intake
Digestion
Absorption
Metabolism
Excess/nutrition loss
What is acute malnutrition?
Develops rapidly in presence of acute stress/ injury
It is short lived and resolves with improvement
What are the consequences of untreated malnutrition?
Impaired immunity, increased risk of infection
Decreased wound healing
Increase complications
Poor response to medical or surgical therapy (3x more likely to have post op complications)
Decreased growth or development of infant/ child
Death
When would a patient have parenteral nutrition?
Inadequate or unsafe oral or enteral intake
A non functional or perforated GIT
How is parenteral nutrition (PN) administered?
IV
What would be the short term (inpatient) reasons of using PN?
Post surgery if pt NBM (gut rest) for less than 7 days
Obstruction in gut
Severe shock or gut infection
Malnourished or unable to eat
What would be the short term (home) reasons of using PN?
Not functioning gut
Not enough gut to function e.g surgery
-some pts can eats small amounts
-may or may not be permanent
What are the oral sources of nutrition and the (parenteral) sources?
Water (water)
Protein (La.a mixture)
Carbohydrate (glucose)
Fat with essential F.A (lipid emulsion with essential F.A)
Vitamins (vitamins)
Minerals (trace elements)
Electrolytes (electrolytes)
Describe the principles of water volume:
Accounts for around 60% of total body weight
Risk of over or under dehydration
What is the calculation for maintenance fluid?
1500ml + (20ml x each kg of body weight over 20kg)
What are the factors affecting dehydration?
Fever
Acute anabolic state
High temp
Low humidity
GI losses
Burns/ wounds
Blood loss
What are the factors affecting fluid overload?
High humidity
Blood transfusion
Drugs
CF
RF
Describe the features of amino acids as to how they relate to being essential for the body:
20 a.as required for protein synthesis and metabolism
8 essential can’t be synthesised
5 conditionally essential- patients needs exceeds the synthesis in clinically stressed conditions
Which commercially available solutions are there for N (amino acids)?
Synthamin
Vamin
Vaminolact (paediatric)
What are the normal mass of nitrogen prescribed in PN bags?
9g, 11g, 14g or 18g
Why shouldn’t amino acids solutions be administered alone to peripheral circulation?
Amino acids solutions are hypertonic to blood
How much nitrogen does an average adult require?
0.2g N/kg/day
How much non protein energy can an average adult be maintained on?
25-35 non protein Kcal/kg/day
Sourced from both lipids and glucose (dual energy) to minimise the risk of giving too much of either
Why shouldn’t glucose be used alone as an energy source?
Risk of hyperglycaemia
Fatty infiltration of liver (as excess glucose goes into F.A)
Excessive CO2 production
Excessive consumption of oxygen
Excessive F.A deficiency
How many Kcal is 1g of anhydrous glucose?
4Kcal
How many Kcal is 1g of oil?
10Kcal
How much lipid (g) should a patient receive a day?
2.5g lipid/ kg/ day
What is the source of lipids in PN bags?
Mixture of soybean oil+ egg phospholipids
What are the essential fatty acids?
Linoleic acid (52%)
Linolenic acid (8%)
What are other non-essential fatty acids?
Oleic acid (22%)
Palmitic acid (13%)
Stearic acid (4%)
Other (11%)
What are the commercially available sources of lipids?
Intralipid 10%- most common, combine with glucose
ClinOleic 20%
What are the advantages of using lipid emulsions?
Large amount of energy in small amounts of fluid (good for fluid restricted)
Allows peripheral admin (isotonic and venoprotective effect)
Contains some fat soluble vitamins (E&K)
Prevents/ reverses essential F.A deficiency
What are the 2 groups of micronutrients?
Trace elements
Vitamins
What are the main factors affecting micronutrient requirements?
Baseline nutritional state on starting PN
Increase loss
Increase requirement - increase metabolism
Organ function
How can baseline nutrition state on starting PN affect micronutrient requirements?
Acute or chronic onset of illness
Dietary history
Duration and severity of inadequate nutritional intake
How can increase loss affect micronutrient requirements?
Small bowel fistulae/ aspirate- rich in zinc
Biliary fluid loss- rich in copper
Burn fluid loss- rich in Zn, Cu, Se
How can organ function affect micronutrient requirements?
Liver failure- Cu and Mn clearance decreases
Renal failure- Al, Cr, Zn and Ni clearance reduced
Name the trace elements:
10 known
Fe, Cu, Zn, F, Mn, I, Co, Se, Molybdenum, Cr
What are the commercially available solutions of trace elements?
Additrace- 10ml vial
Decan
What are the commercially available vitamin preparations?
Vitilipid N adult- fat soluble
Solivito N- water soluble
Name the electrolytes:
Na, K, Ca, Mg, P, Cl, Acetate
What are the main features of PN bags?
A.as
Glucose+ lipids
Trace elements
Vitamins
Electrolytes
What are the 2 available bags for PN?
Standard- contain an average of what is needed and can add to it
Scratch bags
Describe central admin of PN:
Central line is inserted into chest
-jugular or subclavian vein
The line is tunnelled under the skin
Position is confirmed by X-ray
Risk of complications/ infection
Invasive and costly
Describe peripheral admin of PN:
Can easily get damaged
Considered first line if possible
Need good line care and low tonicity feeds
Pts can be successfully maintained for many weeks
Can be complicated by phlebitis- inflammation of vein
What is the peripheral solution osmolality?
800mOsmol/L
What are the indications of peripheral PN admin?
Duration likely to be short term- long term damages vein
Supplement feeding
Compromised access to central
No immediate facilities to insert central catheter
High risk of fungal/bacterial sepsis
CI to central/ venous catheterisation
What are the CIs for peripheral PN admin?
Inaccessible peripheral veins
High osmolarity of the PN formulation e.g high N
What are the indications of central PN admin?
Longer term feeding is anticipated
Peripheral route is inaccessible
High tonicity formulations are required
What is the central solution osmolality?
2000mOsmol/L
How should PN be administrated?
Always under control of infusion pumps via a giving set, to avoid overload of fluid, nutrition and electrolytes
Should be administered at room temp, remove from fridge 3 hours before connection
Describe the problems with physical stability in PN bags and the solutions:
Precipitation
-potential to infuse solid particles- fatal emboli
Lipid destabilisation
-lipid globules may come together and coalesce (bubbles)
-occlude the lung microvasculature (respiratory and circulatory blockages)
All PN fluids are passed through a filter when infused into pt
Describe the problems with chemical stability in PN bags and the solutions:
Vitamins
-readily undergo chemical degradation
-often define shelf life
-Vit C is least stable
All bags are protected from light during storage and infusion
Describe the problems with microbial stability in PN bags and the solutions:
Highly nutritious medium- potential for microbial growth
Aseptic techniques
What are the monitoring parameters when a patient is on a PN bag?
Clinical symtoms
BP, temp, fluid balance, weight
N balance, lipid tolerance, acid base profile
LFTs, electrolyte profile, BG, haematology, CRP, Ca, albumin
What are the complications of PN?
Line blockages, can be caused by:
-fibrin sheath forming around the line or athrombosis blocking the tip
-internal blockage of lipid, blood clot, or salt and drug precipitation
-line kinking
-blockage of protective line filter
Line sepsis
Thrombophlebitis
What is re-feeding syndrome?
A metabolic complication occurring when the infused nutrition exceeds the tolerance of a previously malnourished patient
Can cause significant mortality/ morbidity
What should you do if someone is at risk of developing re-feeding syndrome?
Start feeding slowly- one bag over 48 hours instead of 24 hours- as can’t go rapidly from metabolising fat to carbohydrate, as if too much, an increase in insulin secretion so metabolic disturbances e.g K+/ Na+ loss
Describe the body fluid compartments:
40L
Intracellular fluid (25L)-physcial structure/metabolic process
Extracellular fluid (15L)
-plasma (3L)
-interstitial fluid (12L)
Describe the water intake:
Fluids= 1500ml
-tea/coffee doesn’t count as liquid as caffeine causes diuresis
Food=800ml
Metabolism= 300ml
-mainly carb metabolism
Describe the water output:
Urine= 1500ml
Stools= 200ml
Insensible losses (can’t be measured) e.g skin/lungs = 900ml
How much fluid should an average adult intake a day?
25-30ml/kg/day
Describe the movements of fluid across the cell membrane:
Cell membrane is semi-permeable
Water and small molecules from the intracellular fluid to intravascular fluid
Means vital nutrients into cells and waste products out
Na+/K+ pumps on membrane ensure K+ passes into cells, Na+ passes out of cells, so higher intracellular K+ and lower intracellular Na+
Na conc affects volume of extracellular components
Increase Na, Increase tonicity/osmotic pressure of blood volume so increases thirst
Describe fluid volume homeostasis in the body:
ADH- in hypothalamus produced and released in posterior pituitary
Increase thirst, decreased renal excretion of waste
RAS system- when blood flow to kidney decreases if dehydrated
-activated by falling renal profusion
-increase aldosterone, increase Na and water retention
In what conditions would you decrease the amount of fluid given to a patient?
Renal impairment
Hepatic impairment
Cardiac failure
Head injury- potential for increase in intracranial pressure, more fluid, increase volume
In what conditions would you increase amount of fluid given to a patient?
Vomiting/diarrhoea
High output stomas
Fistulas
Burns- skin is a barrier to fluid loss
What are the indications for giving fluid to a patient?
To correct acute losses or maintain homeostasis:
-blood volume -fluid levels -organ profusion and function
Prolonged failure of oral intake e.g mucocytosis
Excessive losses e.g diarrhoea
NBM
Special case patients e.g burns, brain injury, children
What are the consequences if you calculate fluid balance wrong?
Electrolyte imbalance- arthymias
Peripheral oedema
Pulmonary oedema
Renal impairment
Acid/ base disturbance
What are the symptoms of dehydration?
Thirst
Decreased skin turgor (elasticity)
Increase capillary refill time- press finger, should go pink within 2 seconds
Altered level of consciousness
Tachycardia- consider current medication e.g B blocker
What is the BP like of a patient with fluid depletion/overload?
Lowered/normal or raised
What is the respiratory like of a patient with fluid depletion/overload?
Rapid, shallow/ rapid, moist cough
What is the pulse like of a patient with fluid depletion/overload?
Rapid, weak/ rapid
What are the different types of fluid?
Crystalloids
Colloids
Blood- for major haemorrhage
Why can’t you give give water (IV) as fluid?
It isn’t isotonic with fluids in body- can cause haemolytic (breakdown of RBCs) and it is painful to inject something which isn’t isotonic
Name some examples of crystalloid fluids:
0.9% NaCl
5% Glucose
Dextrose-saline combination
Hartmann’s
Name some examples of colloid fluids:
Albumin
Dextran
Gelatin
What are crystalloid solutions?
Solutions of small molecules in water e.g ions and or glucose
Isotonic with plasma
Distribution in the body is determined by Na contents
Increase Na, more fluid will be retained within the extracellular space ‘plasma expander’ if lost fluid
Decreases Na- distributes more evenly through total body water
What is the caution in crystalloid solutions?
Hypernatruaemia- in extended periods
Describe 0.9% sodium chloride:
9g/150mmol of Na+ and Cl-/100ml
Distrubtes into the whole extracellular space (intravascular and interstitial spaces)
‘Normal saline’
Can be given IV/SC
Isotonic
Used as a plasma expander
What are the risks of using 0.9% sodium chloride?
Hypernatraemia and hyperchloramiea acidosis in excess use
Describe 5% glucose:
Essentially water
Distributes throughout the intravascular, interstitial and intracellular compartments
Some caloric content
Glucose is primarily metabolised therefore does NOT cause plasma expansion
Describe dextrose saline:
Glucose and sodium chloride
Usually 4% glucose/ 0.18% NaCl
Isotonic
Glucose based fluid+ sodium based fluid to boost intravascular volume
Up to 3L over 24 hours
Not long term as doesn’t contain other electrolytes
Describe Hartmann’s fluid:
Balanced salt solution
Most comparable to plasma:
-Na+, K+, bicarbonate, Cl-,Ca2+, pH, osmolarity
No glucose
Routine maintenance
Resuscitation- haemodynamically unstable/ critically ill
Particularly where large volumes required
What are colloid solutions?
Dispersions of large organic insoluble molecules in a carrier solution
Provide more volume expansion than crystalloids
Characteristics depend on molecular size (larger increase doA)
Contribute to oncotic pressure (colloid osmotic pressure)
What is oncotic pressure?
Osmotic pressure exerted by proteins in blood plasma that usually tends to pull water into the circulatory system
Describe Albumin as a colloid fluid:
Derived from human serum (blood donations)
4.5%-isotonic
20%- hypertonic (additionally draws extra fluid into plasma)
Short DoA
Expensive
What is Albumin fluid used for?
Intensive care unit
Shock: burns, haemorrhage, surgical losses and trauma
Describe Dextrans:
Synthetic colloid
Poly-dispersed solutions
Dextran 70- average MW 70000 (longer circulation and increase DoA)
Interference with blood clotting, allergic reactions and cross matching
Anaphylaxis
Renaly excreted so needs reasonable renal function
Describe Gelatin:
Synthetic colloid
Complex carbohydrate molecules
Osmotic force
2 main types:
-Modified gelatin (Gelofusine)-larger mw
-Polygelines (Haemaccel)
Anaphylaxis, as comes from animal collagen
Describe the advantages of using crystalloid fluid:
Maintain osmotic gradient
Widely available
Low risk of ADRs
Inexpensive
Describe the advantages of using colloid fluid:
Smaller volumes (1L of colloid=3L crystalloid)
Faster to give
Longer half life
Startches can reduce capillary leaks into intestinal space- lasts about 12 hours from initial onslaught, colloids can decrease this
Describe the disadvantages of using crystalloid fluid:
Poor maintenance of oncotic pressure
Short half life
Describe the disadvantages of using colloid fluid:
Max volume per day
ADRs e.g itching
Expensive
Describe blood as a fluid:
Used when blood loss exceeds 20% of total blood volume (before 20% use crystalloids/ colloids)
-Whole blood
-Packed cells
-Plasma (FFP- fresh frozen plasma)
Describe whole blood as a type of fluid:
Complete (RBCs, WBCs, platelets)
Describe packed cells as a type of fluid:
Removed platelet rich plasma
Packed RBCs, so same O2 carrying capacity but not volume
Describe plasma as a type of fluid:
What remains after RBCs removed
Water, electrolytes, proteins , globulins, clotting factor
Used when patient has a clotting deficiency/ blood disorder
What can be the complications of using blood as a fluid?
HF (excess preload)
Acute respiratory distress syndrome
Biochemical abnormality
Haemodilation
Dilutional coagulopathy
Renal impairment
State the NICE guideline for IV fluid therapy in adults in hospital:
5R’s
Resuscitation
Routine management
Replacement
Redistribution
Reassessment
Describe the Resuscitation step in the NICE guidelines:
Used in medical emergency/ acute circulatory shock
500ml bolus of crystalloid over 15 mins- sodium containing (range 130-154mmol) e.g NaCl 0.9% 500ml
Repeat as necessary up to 2L
Continuous monitoring
Describe the Routine maintenance step in the NICE guidelines:
Next step after resuscitation or post op etc
25-30ml/kg/day fluid (max 2.5L- use IBW if obese)
Up to 1mmol/kg/day of K+/Na+/Cl-
50-100g per day of glucose
e.g 4% glucose/ 0.18% NaCl +20mmol KCl 500ml over 8hrs x2
Describe the Replacement and Redistribution step in the NICE guidelines:
Adjust IV prescription for existing electrolyte deficits/ excesses and ongoing losses (e.g GI drans) in context of pts condition
Adjust IV prescription for redistribution e.g vascular leakage from intravascular compartment into interstitial space during inflammation, ascites- 3rd space losses
Describe the Reassessment step in the NICE guidelines:
Reassess needs and adjusted at least daily
Monitor for adverse effects e.g fluid overload
What are the issues with KCl with fluid bags?
KCl concentrate can be fatal (cardiac arrest)
Ampoules of 10%,15% or 20% available are similar and also to NaCl and WFI
When added to bags they must be mixed thoroughly as can sit at bottom
What are the solutions to overcome the problem of KCl with fluid bags?
Use commercially available diluted bags where possible- hospital policy
Also treat them like CDs- separate storage
Distinguished labelling
Name the types of admin used in fluids:
Peripheral venous access
Central venous access
Subcutaneous administration
Describe peripheral venous access for fluids:
Forearm
Back of hand
Small vein
Short to mid term length of use- need to replace every 24 hours
Describe central venous access:
IV therapy longer than 10 days
Poor peripheral access
Describe subcutaneous admin:
Called hypodermoclysis
Off label
Prolonged admin of fluid- palliative care/elderly
Easier to insert line
Unsuitable for rapid admin
