7 Refeeding Syndrome
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Transcript 7 Refeeding Syndrome
Anurag Goel
ST5
Royal Preston Hospital.
What is It?
Potentially fatal shifts in fluids and electrolytes that
may occur in malnourished patients receiving artificial
refeeding (whether enterally or parenterally)
The hallmark biochemical feature of re feeding
syndrome is hypophosphataemia
JPEN J Parenter Enteral Nutr 1990;14:90-7
Discovery of RFS
Observed & described after WWII
Victims of starvation experienced cardiac and/or
neurologic dysfunction
After being reintroduced to food
Neurologic signs & symptoms developed later
How common is RFS?
True incidence is unknown
Study1 of 10,197 patients, incidence of
hypophosphatemia = 43 %
Malnutrition one of strongest risk factors
Parenteral patients = 100% incidence of
hypophosphatemia (if no PO4 in PN) ; 18% with
PO4 containing PN2.
1. Mineral & Electrolyte Metabolism 1990;16:365-8
2. Nutr Hosp 2006;21:657-60.
Understanding Starvation
Glucose is normally the main fuel.
Starvation - Shifts to protein & fat
Insulin ↓ (due to ↓ availability of glucose)
Catabolism of protein → loss of cellular &
muscle mass → atrophy of vital organs &
internal organs
Respiratory & cardiac function ↓ due to
muscular wasting & fluid/electrolyte
imbalances
Body is now surviving by slowly consuming
itself
Starvation
The serum concentrations of electrolytes may appear
normal in the starved state!!
(Due to alterations in renal excretion rates of
electroytes.)
Effects of Refeeding on the Cardiovascular
System
Increases in heart rate, blood pressure, oxygen
consumption, cardiac output
expansion of plasma volume
Response is dependent on amount of calories,
protein and sodium given
The malnourished heart can easily be given a
metabolic demand that is too high for it to
supply
Effects of Refeeding on the Cardiovascular
System
Congestive Heart Failure is a common
complication of refeeding
Cardiac output can’t increase enough to meet
the needs from the increased plasma volume,
increased oxygen consumption and increases in
blood pressure and heart rate
Effects of Refeeding on the Respiratory
System
Excess carbon dioxide production and
increased oxygen consumption from giving
too much glucose and overfeeding
A person with malnutrition-induced
respiratory muscle wasting can get short of
breath
Can’t sustain an increased ventilatory drive
Pulmonary edema due to increased water
load
Effects of Refeeding on the Gastrointestinal
System
Activity of the brush border enzymes and
pancreatic enzyme secretion return to
normal with refeeding
Requires a period of readaptation to food to
minimize GI complaints
Diarrhea, nausea and vomiting
Main Pathophysiologic
Features
Disturbances of body-fluid distribution
Abnormal glucose & lipid metabolisms
Thiamine deficiency
Hypophosphatemia
Hypomagnesemia
Hypokalemia
Hypophosphatemia
Phosphorus is predominantly intracellular
Impaired cellular-energy pathways
Adenosine triphosphate (ATP)
2,3-diphosphoglycerate (2,3 DPG)
Impaired skeletal-muscle function
Including weakness & myopathy
Seizures & perturbed mental state
Impaired blood clotting processes & hemolysis
also can occur
Hypomagnesemia
cofactor in most enzyme systems, including oxidative
phosphorylation and ATP production.
also necessary for the structural integrity of DNA,
RNA, and ribosomes.
Mild cases: often asymptomatic
Severe cases:
Cardiac arrhythmias
Abdominal discomfort
Anorexia
Tremors, seizures, & confusion
Weakness
Hypokalemia
major intracellular cation. Serum levels may remain
normal in starvation!
Features:
Cardiac arrhythmias
Hypotension
Cardiac arrest
Weakness
Paralysis
Confusion
Respiratory Depression
Thiamin Deficiency
Functions as a cofactor in intermediary carbohydrate
metabolism (TCA cycle)
Amount needed depends on carbohydrate ingested.
Mental confusion, ataxia, muscle weakness, edema, muscle
wasting, tachycardia and cardiomegaly
Wernicke’s encephalopathy can be precipitated by
carbohydrate feeding in thiamine-deficient patients
Who is at risk?
Some risk:
People who have eaten little or nothing for more than
5 days
REMEMBER: Even an overweight or obese
patient can be malnourished & a victim for RFS
NICE guidelines (2006)
Who is at risk?
High Risk
Either patient has 1 or more:
BMI <16
Unintentional weight loss >15% in past 3-6 mo
Little/no nutritional intake for 10 days
Low levels of potassium, phosphate, or magnesium before
feeding
Or patient has 2 or more:
BMI <18.5
Unintentional weight loss >10% in past 3-6 mo
Little/no nutritional intake for >5 days
History of alcohol misuse or drugs
NICE guidelines (2006)
Patients at high risk:
Anorexia nervosa
Chronic alcoholism
Oncology patients
Postoperative patients
Elderly
Uncontrolled diabetes
mellitus
GI fistulas
Chronic malnutrition:
Marasmus
Prolonged fasting or
low energy diet
Morbid obesity with
weight loss
Long term antacid
users
Long term diuretic
users
Managing refeeding syndrome
Identifying patients who are at risk.
Prevent Refeeding syndrome.
Once refeeding starts: Replace K, PO4, Mg even if
normal (not if levels high)
Potassium: 2-4 mmol/kg/day
Phosphate: 0.3-0.6 mmol/kg/day
Magnesium: Oral 0.4 mmol/kg/d OR i.v. 0.2mmol/kg/d
PS : Prefeeding replacement is not required even if electrolytes abnormal !!
Managing refeeding syndrome
Replace K, PO4, Mg even if normal (not if levels high)
Potassium: 2-4 mmol/kg/day
Phosphate: 0.3-0.6 mmol/kg/day
MANTAINANCE
Magnesium: Oral 0.4 mmol/kg/d OR i.v. 0.2mmol/kg/d
Managing refeeding syndrome
Feed cautiously – 10kcal/kg for first 2 days,
5kcal/kg in extreme cases Increase slowly (over 4 7 days)
No more than 150 to 200 gm of glucose
1.2-1.5 gm of protein per kg actual bodyweight
20-30% of calories from fat
PS: Weight Gain is NOT the goal in first 2 weeks.
Hypo-phosphataemia verses initial
feed rate
Phosphate levels as a function of 1st day feed rate
(kcal / kg).
100
90
80
% Patients
70
whose
phosphate 60
dropped 50
below 0.65 40
mmo/l
30
20
10
0
P = 0.008
Feed-rate kcal / kg
≤ 10. N = 14
> 10, ≤ 20. N = 26
> 20. N = 8
Managing refeeding syndrome
Pabrinex (high dose thiamine) and balanced
multivitamin/mineral supplement
ORAL: Thiamine 200 – 300 mgs + Vit B Co Strong 1-2
tabs TDS X 10 days
IV: Pabrinex OD X 10 Days.
first dose being administered at least 30 minutes
before starting feeding.
Electrolytes in Refeeding: phosphate
Oral
One tablet =
16.1mmolPO4,
20.4mmol Na,
3.1mmol K)
i.v. (phosphate
polyfuser) 500ml =
50mmol PO4,
81mmol Na,
9.5mmol K+)
Mild ↓ PO4 (0.6-0.85
mmol/l)
Phosphate Sandoz
(16mmol each) - 2 tds
15mmol PO4 Polyfusor
(150ml) over 12hrs
peripherally
Moderate
↓ PO4 (0.3-0.6 mmol/l)
Phosphate Sandoz
(16mmol each) - 2 tds
25mmol PO4 Polyfusor
(250ml) over 12hrs
peripherally
Preferred route - i.v.
Severe ↓ PO4 (<0.3
mmol/l)
Not recommended
50mmol PO4 Polyfusor
(500ml) over 24hrs
peripherally,
measuringPO4 at 12hrs.
Precautions
Renal impairment – Half initial dose in significant
renal impairment + monitor levels carefully
Low calcium levels - Phosphate administration can
cause hypocalcaemia
Rapid IV infusion may cause metastatic soft tissue
calcification
CCF, hypertension : High sodium content of
Phosphate-Sandoz® and Phosphates Polyfusor®
Oral Mg, Ca or Al containing products – binds oral
PO4 and prevent its absorption
Electrolytes in Refeeding: Potassium
Mantainance requirement 2-4 mmol/Kg/Day
ORAL (not preferred)
I.V.
Mild ↓ K (3.0 – 3.5
mmol/l)
Sando K (12mmol each)
1 tds OR
Kay-Cee L 10 mls TDS
(1mmol/ml)
KCl 20mmol in 1000 mls
normal saline or 5%
dextrose over 8hrs.
Moderate
+
↓K
( 2.5 – 2.9 mmol / l)
Sando K (12mmol each)
2 – 3 tds
KCl 40mmol in 1000 mls
normal saline or 5%
dextrose over 8hrs.
Severe
+
↓K
( <2.5 mmol / l)
Sando K (12mmol each)
3 – 4 tds (However
prefer i.v. replacement)
KCl 40mmol in 1000 mls
normal saline or 5%
dextrose over 4 hrs.
Retest before repeating
+
Concentration must not exceed 40mmol/l peripherally.
Maximum infusion rate is 20mmol/hr unless via a central line with ECG monitoring.
CORRECT ↓ Mg+
Electrolytes in Refeeding: Magnesium
Maintenance requirement = 0.2 mmol/kg/day i.v. (or 0.4 mmol/kg/day orally )
Mild to moderate
hypomagnesaemia
(0.5-0.7 mmol/l)
Severe
hypomagnesaemia
(<0.5 mmol/l)
Requirement
i.v.
oral
Initially 0.5
mmol/kg/day over
24 hours iv, then
0.25 mmol/kg/day
for 5 days i.v.
2 gms (8 mmol)
MgSO4 in 100 mls
N.S. Over 3 hrs.
-Magnesium
Glycerophosphate 2
tds (4mmol/tab)
-Magnaspartate 1
(6.5gm) sachet bd
(10mmol/sachet)
-Magnesium oxide
(160mgs) 3.9 mmol
per capsule 2 tds
24 mmol over 6
hours i.v. then as for
mild to moderate ↓
Mg.
3 grams MgSO4 (12
mmol) in 100 mls
N.S. Over 3 hrs. (x2
infusions)
(1 gm MgSO4 = 4
mmol Mg+)
BMJ. Jun 28, 2008; 336(7659): 1495–1498
Electrolytes in Refeeding : Calcium
10-20 mmol calcium ( 40-80ml of Calcium Gluconate
10%) in 500ml of Normal Saline 0.9% over 6-8 hours
Electrolytes in Refeeding : Sodium
Sodium must be given carefully to prevent
overexpansion of the extracellular fluid
Upon refeeding, renal sodium losses stop
Hence Sodium and water retention
Restrict Sodium <1 mmol/Kg/day
Fluid in Refeeding
Refeeding results in expansion of the extracellular space
and fluid must be given carefully
Aim for fluid replacement 20 – 30 mls/Kg/Day
Weight gain greater than 1 kg the first week is due to
fluid retention
Fluid may need to be restricted to 800 to 1000 mls/day
Increases in blood pressure, heart rate and respiratory
rate may be early signs of fluid excess
Monitoring
K+ - check daily.
Once or twice weekly once stable.
Mg2+ and Po43- daily monitoring.
Once weekly when stable.
BMs 4 times a day – beware hyperglycaemia.
Priorities – Only one cannula!!
Aim to correct potassium
Then bring magnesium and calcium to safe levels, not
necessarily in the normal range
Then bring phosphate levels up to a safe, not
necessarily normal value
This may need to be done in stages to allow for further
calcium or magnesium infusions
Priorities – Only one cannula!!
Aim to correct potassium
Then bring magnesium and calcium to safe levels, not
necessarily in the normal range
Then bring phosphate levels up to a safe, not
necessarily normal value
This may need to be done in stages to allow for further
calcium or magnesium infusions.
Can we mix the KCl with MgSO4 and or Cal Gluconate??
Summary Points
Characterized by hypophosphatemia
Patients at high risk: undernourished, little or no
energy intake for > 10 days
Start refeeding at low levels
Correction of electrolyte & fluid imbalances before
feeding is not necessary (do not delay feeding)
Questions