Re-feeding Syndrome

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Re-feeding Syndrome

• Sunday Pam

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What is RS?

• Metabolic alterations that occur during nutrition
  repletion of underweight, severely malnourished
  or starved individuals.
• Hallmark is severe hypophosphataemia and
  associated complications
• Multisystemic manifestations
• Classic reports on WWII objectors

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Why RS?Biochemical Basis of RS

• ?Phosphate
• ?Magnesium
• ? Potassium
• ?Thiamine
• ?Protein
• Others Calcium, Sodium, Acidosis

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Physiology of starvation

• 24-72 hours
• Gluconeogenesis from liver muscle for
  glucose-dependent energy for brain, rbc, renal
  medulla.
• Post 72 hours
• ketones from FFA with protein sparing
• ?Glycogenolysis
• ?BMR
• ?Secretion of Insulin
• ?FFA use by brain as primary energy source

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Physiology of Starvation 2

• Others
• ?Thyroid functions
• ?antidiuretic hormone
• ?Growth Hormone
• Hyperaldostronaemia
• Hypercortisolaemia

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Risk factors

• Anorexia nervosa
• Classic marasmus/kwashiorkor
• Chronic diseases eg neoplasia, FTT,
• Morbid obesity with massive weight loss
• Starvation for short periods from stress

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Pathological challenges in starvation

• Cardiac volume, mass and electrical function
  compromised
• Intestinal atrophy
• Impaired synthesis of B-lipoprotein leads to
  Fatty liver
• Pancreatic atrophy
• Exocrine
• /-endocrine

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Pathophysiology of Refeeding

• Feeding by any means
• Glucose surge
• Increased glucose metabolism
• Increased demand for phosphorylated intermediates
• Increased cellular uptake of phosphates
• Pre-existing low phosphates
• Hypophosphataemia

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Issue of fluid

• Complex interplay between Na, H2O CHO
• Antidiuretic effect of insulin
• Low GFR
• Weak myocardium
• Effects of PO4, K, Mg2

• Others
• ? BMR
• ?Muscle activity
• ?Perivascular fluid mobilisation
• ??Protein synthesis

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Clinical manifestations of RS

• Hypophosphataemia-Occur with PO4 levels
  lt0.5mmol/L
• ?O2 transport/delivery
• ?Cardiac function
• ?Diaphragmatic contractility
• Respiratory failure
• Paraesthesias
• Somnolence
• Confusion
• Seizures
• Coma

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Clinical manifestations 2

• Hypokalaemia-lt2.5mmol/L
• Nausea/vomiting
• Weakness
• Paralysis
• Rhabdomyolysis
• Muscle necrosis
• ECG-ST ?, T flat or -, U waves

• Arrhythmias
• Atrial Tachycardia
• Bradycardia
• Atrioventricular block
• PVC
• V Tach
• V Fib

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Clinical manifestations 3

• Hypomagnesaemia
• Serumlt1.5mg/dL
• Cofactor in oxidative phosphorylation
• HypoMg complicates Rx of ?K and ? PO4
• Weakness
• Muscle twitching
• Tremor
• Diarrhoea
• Refractory ?K ?PO4
• Tetany
• Seizures
• Coma

• ECG
• ?PR
• ?QRS
• ?QT
• ST?
• Arrhythmias
• A Fib
• Torsades de pointes
• V fib
• V tach

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Clinical manifestations 4

• Thiamine/?other vitamins
• Lactic acidosis
• Encephalopathy

• Sodium and fluid
• Complex consequence
• Fluid retention
• Pulmonary oedema
• Cardiac failure

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Prevention

• Identify those at risk
• Long standing malnutrition
• Severe wt loss
• Avoid over zealous re-feeding
• Start slow and Go slow
• Correct any electrolyte abnormality before
  starting
• Cautious monitoring and correction of electrolyte
  imbalance
• Vitamin supplements
• Interrupt feeding if RS manifests

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Approach to Treatment

• Look out for features of RS
• Thiamine for neurologic features
• Respiratory distress O2
• Fluid overload Diuretics
• Weight adjustment (ideal body weight)

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Rx Hypophosphataemia

• PO4 doses largely empiric
• Oral route preferred if possible
• May cause diarrhoea
• Absorption unreliable
• Suitable for mild cases
• Parenteral for symptomatic/Severe
• Monitor serum in 2-4hrly initially, dly later
• Thrombophlebitis, hypocalcaemia

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Rx HypoPO4 2

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Rx Hypokalaemia

• Oral route feasible when mild
• Unpleasant taste and Diarrhoea
• Severe case lt2.5mmol/L
• Parenteral at 0.3-0.5mmol/kg/hr
• Faster rates with ECG monitoring
• Must correct hypomagnesaemia to succeed
• Maximum concentration for peripheral vein
  infusion 80mmol/L
• Monitor serum levels closely

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Rx hypomagnesaemia

• IV route preferred in severe cases
• Poor tissue distribution
• Rapid renal clearance
• Total correction requires several days
• 1-1.5mmol/kg over 2-6 hours(maximum
  8.1mmol/hour). Some recommend 6-12 hrs.
• Too rapid infusion ? urinary loss
• Serum levels after 12-24hrs

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Restarting nutrition

• Caution
• All electrolyte abnormalities must be treated
• Electrolytes suppl to be higher than doses _at_
  onset of RS
• Must be symptom free before restarting
• Multivitamin suppl
• Initiate feeds at lt50 pre-RS rate, reach goal in
  4-5 days
• Close monitoring for repeat RS

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Restarting feeds 2

• Calories up 175kcal/kg/day
• Protein up to 4g/kg/day
• Micronutrient repletion
• Reach goal in about 1 week

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Thank you
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Bibliography

• Kraft MD et al. Review of Refeeding syndrome.
  Nutr Clin Pract 200520625-33
• Hearing S. Refeeding syndrome. BMJ 2004
  328908-9.
• Korbonits M et al. Metabolic and hormonal changes
  during refeeding period of prolonged fasting. Eur
  J Endocrinol 2007157157-166.
• Dunn R et al. Refeeding sndroe in hospitalized
  Pediatric Patients. Nutr Clin Pract 200318327
• Refeeding synrdrome. Wikipedia
• El-Sayel HL. Structural and functional affection
  of the heart in protein energy malnutrition
  patients on admission and after nutritional
  recovery. Eur J Clin Nutr 2006 60502-10.