Lecture 3 Refeeding Syndrome Flashcards
Define Refeeding Syndrome
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.
Risk factors for RFS in clinical practice
- 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.
Examples of clinical populations who may experience refeeding syndrome
- 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.
pathophysiology of refeeding syndrome
What can refeeding syndrome lead to?
This can lead to abnormalities in neurologic, cardiac, hematologic, neuromuscular and pulmonary function; people have died from this.
What are signs for risk of refeeding syndrome?
- Hypophosphatemia
- Hypokalemia
- Hypomagnesemia
- Vitamin/Thiamin Deficiency
- Fluid and Sodium Retention
What happens when CHO introduced to someone who has not eat for a long time?
When introduce CHO → insulin is released → get uptake of phosphate, magnesium (Mg) and potassium (K+) into cells
What are phosphate and magnesium important for?
Both are important for ATP generation from glycolysis
What phosphate levels indicate risk for RFS?
- 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)
Clinical manifestations of hypophosphatemia
memory loss, bone pain, bruising, bleeding, lethargy, joint stiffness, arthritis, cyanosis, decreased cardiac output, respiratory failure, seizure, coma, death
Monitoring phosphorous levels
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).
Clinical Manifestations of Hypokalemia
Nausea, vomiting, constipation, weakness, paralysis, respiratory compromise, muscle necrosis, myocardial contraction problems, cardiac arrythmias, bradycardia and atrial tacchycardia, ventricular fibrillation and sudden death
Serum levels of potassium
- 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
Supplementing potassium
- 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)
Problem with potassium supplementation
Potassium tends to be gastric irritant
Serum levels of magnesium
- Normal Serum levels :0.8 -1.2 mmol/L
- Hypomagnesium: serum levels < 0.8 mmol/L
Supplementing Mg
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
What is usually seen with hypomagnesium?
Usually see hypocalcemia and hypokalemia (which are very serious)
Clincal manifestations of hypomagnesium
muscular weakness, vertigo, ataxia, leg cramps, nausea and vomiting, paresthesisa, hyperinsulinism and glucose intolerance, cardiac arrythmias etc.
Clinical manifestations of thiamine deficiency
- Wernike’s encephalopathy (thiamin), lactic acidosis, death
- Wet Beri Beri (can lead to congestive heart failure) vs Dry Beri Beri (effects CNS and PNS)
sodium and fluid with refeeding syndrome
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
*
What to monitor with sodium and fluid retention
- 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
Preventing RFS with electrolyte supplementation
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)
Risk assessment and management of RFS algorithm
Starting tube feeds to prevent refeeding syndrome
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.
Treatment of refeeding syndrome
- 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
HOw can sodium and fluid retention be avoided?
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
What weight to use for patients at risk of RFS
Always use best estimate of dry weight in calculation of nutritional requirements in patients at risk for refeeding syndrome!
Role of RD
ensure careful monitoring of fluid and electrolyte status, judicious increasing within the TFI of nutritional intervention.
Starting protein, fat and dextrose for TPN
- 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.
Preventing RFS for severely cachetic
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
Rates for tube feeding
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.
Overall recommendations for feeding strategies
Electrolyte serum levels that require repletion
