Lecture 3 Refeeding Syndrome

Question 1

Define Refeeding Syndrome

Answer 1

Refeeding syndrome is a syndrome consisting of metabolic disturbances that occur as a result of reinstitution of nutrition to patients who are starved, severely malnourished (with/without cachexia) or metabolically stressed due to severe illness.

Question 2

Risk factors for RFS in clinical practice

Answer 2

• Patients who have gone for prolonged periods of little to no nutritional support where they have lost significant amounts of weight (may or may not be underweight)
• And/or patients who have a syndrome associated with elevated resting energy expenditure (e.g cancer cachexia, burns) who may or may not have lost weight.

Question 3

Examples of clinical populations who may experience refeeding syndrome

Answer 3

• short gut
• eating disorders
• some cancers (e.g lung)
• and/or conditions of hypermetabolism (e.g burns, short gut, end-stage liver failure). Usually this would could with weight loss but this is not the sole criteria.
• It could also be when patients have had very low amounts of oral and/or nutritional support for pro-longer periods.

Question 4

pathophysiology of refeeding syndrome

Answer 4

Question 5

What can refeeding syndrome lead to?

Answer 5

This can lead to abnormalities in neurologic, cardiac, hematologic, neuromuscular and pulmonary function; people have died from this.

Question 6

What are signs for risk of refeeding syndrome?

Answer 6

• Hypophosphatemia
• Hypokalemia
• Hypomagnesemia
• Vitamin/Thiamin Deficiency
• Fluid and Sodium Retention

Question 7

What happens when CHO introduced to someone who has not eat for a long time?

Answer 7

When introduce CHO → insulin is released → get uptake of phosphate, magnesium (Mg) and potassium (K+) into cells

Question 8

What are phosphate and magnesium important for?

Answer 8

Both are important for ATP generation from glycolysis

Question 9

What phosphate levels indicate risk for RFS?

Answer 9

• Hypophosphatemia < 0.74 mmol/L indicates the patient is likely to get re-feeding syndrome in response to refeeding the patient.
• Levels of phosphorus between 0.75-0.9 mmol/L and potassium values < 3.5 mmol/L in patients who fit the other criteria for refeeding risk, indicate that these patients are at very high risk for developing refeeding syndrome.
• Normal phosphate is 1.1-1.8 mmol/L (up to 2 in children)

Question 10

Clinical manifestations of hypophosphatemia

Answer 10

memory loss, bone pain, bruising, bleeding, lethargy, joint stiffness, arthritis, cyanosis, decreased cardiac output, respiratory failure, seizure, coma, death

Question 11

Monitoring phosphorous levels

Answer 11

Monitor levels daily with refeeding and supplement with either oral or IV phosphate (depends on severity of hypophoshatemia)
* often when serum levels below 0.7 mmol/L; need IV source in doses ranging from 0.16-0.32 mmol/kg over 6 hours).

Question 12

Clinical Manifestations of Hypokalemia

Answer 12

Nausea, vomiting, constipation, weakness, paralysis, respiratory compromise, muscle necrosis, myocardial contraction problems, cardiac arrythmias, bradycardia and atrial tacchycardia, ventricular fibrillation and sudden death

Question 13

Serum levels of potassium

Answer 13

• Normal serum levels: 3.5-5 mmol/L (slightly higher for children)
• Hypokalemia < 3.5 mmol/L (in children < 3.6 mmol/L)
• Important to monitor serum levels q daily if levels less than 3.0 mmol/L during re-feeding

Question 14

Supplementing potassium

Answer 14

• May need to supplement with oral potassium in the range of 0.5 mmol/kg/d (MD to prescribe)
• Typically in forms of KCL, or K-citrate
• May need to supplement IV route if serum
  levels < 2.5 mmol/L (note this is done by MD)

Question 15

Problem with potassium supplementation

Answer 15

Potassium tends to be gastric irritant

Question 16

Serum levels of magnesium

Answer 16

• Normal Serum levels :0.8 -1.2 mmol/L
• Hypomagnesium: serum levels < 0.8 mmol/L

Question 17

Supplementing Mg

Answer 17

Typically don’t supplement unless levels range below 0.5-0.6 mmol/L;(varies between centres)
* patients are typically asympotomatic until Mg levels fall below 0.4 mmol/L
* Typically supplement with magnesium oxide, glucoheptonate or hydroxide forms; causes diarrhea

Question 18

What is usually seen with hypomagnesium?

Answer 18

Usually see hypocalcemia and hypokalemia (which are very serious)

Question 19

Clincal manifestations of hypomagnesium

Answer 19

muscular weakness, vertigo, ataxia, leg cramps, nausea and vomiting, paresthesisa, hyperinsulinism and glucose intolerance, cardiac arrythmias etc.

Question 20

Clinical manifestations of thiamine deficiency

Answer 20

• Wernike’s encephalopathy (thiamin), lactic acidosis, death
• Wet Beri Beri (can lead to congestive heart failure) vs Dry Beri Beri (effects CNS and PNS)

Question 21

sodium and fluid with refeeding syndrome

Answer 21

Get expansion of extracellular water due to increased sodium and fluid intake.
* this often causes local edema/early weight gain (be careful what weight you use for the patient in calculations of energy/protein requirements)
* Can lead to pulmonary edema, cardiac decompensaton
*

Question 22

What to monitor with sodium and fluid retention

Answer 22

• Fluid intake
• Urine output >1-2 cc/kg/hr
• Serum electrolytes: Na: 135-145 mmol/L (normal range).
• Be careful of sudden increases in weight (>2 kg in one week).
• May need to fluid restrict in early refeeding phases

Question 23

Preventing RFS with electrolyte supplementation

Answer 23

Measure serum electrolytes prior to initiation of feeds; start treatment for electrolyte abnormalities prior to starting nutrition support regimen.
* Most people recommend starting supplementation of phosphorus, potassium and magnesium empirically at start of feeds to minimize electrolyte fluctuations during refeeding.
* If patient on PN may add additional phosphorus, magnesium and potassium to PN solution (above routine concentrations)
* Phosphorus: may need 10-15 mmol of phosphate/1000 kcal to maintain normal serum levels
* Supplement with multivitamins (as high as 200-300 mg of thiamine, folate 1 mg/d)

Question 24

Risk assessment and management of RFS algorithm

Answer 24

Question 25

Starting tube feeds to prevent refeeding syndrome

Answer 25

Start feeds at less than BMR (70-80%) or less than 25% of estimated goal needs; typically this is 15-25 kcal/kg
* Fluid may need to be restricted < 1000 ml/24 hours and sodium of 20 mmol/d
* For children closer to 30 kcal/kg and for infants: 40-50 kcal/kg
* Increase nutrition support slowly over the course of 3- 5 days (expect to take up to 7 days to reach BMR.
* Monitor electrolytes as required.

Question 26

Treatment of refeeding syndrome

Answer 26

• Start laboratory assessment of electrolytes
• Stop nutrition support; start low IV of IV dextrose with electrolytes to prevent rebound hypoglycemia
• IV supplementation of phosphorus, magnesium, and potassium
• Supportive treatment: re: respiration and cardiac function
• Consider renal function
• Adjusted body weight to assess needs
• Restart nutrition support at 50% of the previous rate, increase slowly over 4-7 days

Question 27

HOw can sodium and fluid retention be avoided?

Answer 27

Wt stability in first 8-10 days important to avoid fluid and sodium retention
* we avoided this by institution of strict TFI
* As increase protein intake, get increased diuresis; therefore possible to liberalize TFI

Question 28

What weight to use for patients at risk of RFS

Answer 28

Always use best estimate of dry weight in calculation of nutritional requirements in patients at risk for refeeding syndrome!

Question 29

Role of RD

Answer 29

ensure careful monitoring of fluid and electrolyte status, judicious increasing within the TFI of nutritional intervention.

Question 30

Starting protein, fat and dextrose for TPN

Answer 30

• Protein: start at 0.5-1 g/kg; and slowly increase
• Fat 0.5 g/kg fat and slowly increase
• max dextrose is about 150 g dextrose for high risk patients; and for extreme risk of refeeding 50-100 g dextrose /d in the TPN solution.

Question 31

Preventing RFS for severely cachetic

Answer 31

If severely cachectic or shows signs of refeeding syndrome; start feeds slowly at 15-20 kcal/kg; and then increase slowly to goal of 30-40 kcal/kg. This could take several weeks to achieve.
* Protein: 1.2-1.5 g/kg
* If have cachexia; supplement with phosphorus, magnesium , potassium and multivitamins

Question 32

Rates for tube feeding

Answer 32

Keep rates at 0.2-0.3 cc/kg/hr over 24 hours. Which means over 8 hrs, the rates would be about 0.1 mls/kg/hr and then increase by a max of 0.1 mls/kg/hr
* consider that you might wish to increase feeds q 12 hrs. Very slow and carefully is the way to go…even if it means you only get up to 0.2 mls/kg/hr in the first 24 hrs.

Question 33

Overall recommendations for feeding strategies

Answer 33

Question 34

Electrolyte serum levels that require repletion

Answer 34