Fluids, Electrolytes, and Nutrition PDF

Fluids, Electrolytes, and Nutrition 1. It will probably not meet nutritional needs based on macronutrient and micronutrient concentration restrictions (discussed earlier). 2. For additional calories, increase the percentage of calories administered as lipid. I. Order of mixing (for manual co...

Fluids, Electrolytes, and Nutrition 1. It will probably not meet nutritional needs based on macronutrient and micronutrient concentration restrictions (discussed earlier). 2. For additional calories, increase the percentage of calories administered as lipid. I. Order of mixing (for manual compounding) 1. Add dextrose, AAs, sterile water. 2. Add phosphate. 3. Add other electrolytes (except Ca) and trace minerals. 4. Mix well to ensure that phosphate is evenly distributed and to prevent precipitation with Ca. 5. Add Ca. 6. Observe for precipitates or contaminants. 7. Add lipid if 3-in-1 formulation. (Note: Do not mix dextrose and lipids directly, because the low pH of dextrose can destabilize the lipid emulsion.) 8. Add vitamins last, as close to the time of PN administration as possible in acute care settings, or just before infusion in patients receiving home PN. Factors associated with Ca2+ and phosphate precipitation in PN 1. Increasing pH (more basic) increases the risk of Ca2+ and phosphate precipitation. 2. Increasing Ca2+ or phosphate concentration increases the risk of precipitation. a.  If Ca2+ concentration is 6 mEq/L or less and phosphate concentration is 30 mmol/L or less, the risk of precipitation is low. b. Calcium chloride is more likely to precipitate with phosphate than calcium gluconate; calcium chloride should never be used in compounding PN formulations. 3. The final concentration of AA should be at least 2.5% or greater to prevent Ca2+ and phosphate precipitation. a. AAs form soluble complexes with Ca2+ and phosphate. b. A As provide a buffer system to maintain a lower pH of the PN in an acceptable range to prevent Ca2+ or phosphate precipitation. 4. As the temperature increases, the risk of precipitation increases. a. PN should be refrigerated if not administered within 24 hours of compounding. b. If refrigerated, PN should be administered within 24 hours of rewarming. 5. A 1.2-micron filter (used for a 3-in-1 PN) might not prevent the embolism of a calcium phosphate precipitate, but it should be used anyway to reduce the risk. 6. Order of mixing additives is important to prevent precipitation (see above) 7. The PN should be agitated often during compounding to ensure adequate mixture into solution. J. K. Medication additives in PN 1. In general, medications should not be added to PN. 2. Examples of medication incompatibilities are ceftriaxone (precipitates with Ca), phenytoin (can change the pH of PN), medications containing propylene glycol or ethanol as diluents (e.g., furosemide, diazepam, lorazepam, digoxin, phenytoin, etoposide), and iron dextran (trivalent cations destabilize the lipid emulsion in 3-in-1 PN formulations). 3. Incompatible drugs should be administered through a separate intravenous catheter or a separate lumen of a central venous catheter, if possible. ACCP Updates in Therapeutics® 2023: Pharmacotherapy Preparatory Review and Recertification Course 1-394 Fluids, Electrolytes, and Nutrition 4. 5. If an incompatible intravenous drug is to be administered through the same intravenous catheter as the PN, the PN should be stopped, followed by a compatible flush before and after drug administration. The volume of flush should be sufficient to clear the entire catheter of PN and of drug (typically about 10 mL if flushing the port closest to the patient); for drugs requiring longer infusion times, see below for precautions to prevent rebound hypoglycemia with prolonged interruptions of PN. Only regular insulin is compatible with PN. L. PN complications 1. Catheter-related infections are caused primarily by Staphylococcus aureus and Candida albicans. 2. Catheter insertion complications (e.g., pneumothorax, incorrect placement) are possible. 3. Peripheral venous thrombophlebitis can occur with peripheral catheter placement. Risk is increased by day 4 of catheterization; therefore, site should be rotated every 3 days. 4. Fluid imbalance can occur. 5. Acid-base imbalances are usually related to the patient’s underlying condition; however, excessive chloride salts in the PN can cause a metabolic acidosis, whereas excessive acetate salts in the PN can cause a metabolic alkalosis. 6. Hyperglycemia can lead to nosocomial and wound infections. 7. Gut atrophy can occur. 8. Overfeeding can cause hepatic steatosis, hypercapnia, hyperglycemia, and azotemia. 9. Essential fatty acid deficiency can occur. a. Symptoms include skin desquamation, hair loss, impaired wound healing, hepatomegaly, thrombocytopenia, fatty liver, and anemia. b. It can occur within 1–3 weeks of a lipid-free PN. 10. Refeeding syndrome can occur in acutely (can include critically ill patients) or chronically malnourished patients when EN or PN is initiated. a. Characterized by hypophosphatemia, hypokalemia, hypomagnesemia b. Can cause cardiac dysfunction, respiratory dysfunction, and death c. Prevention of refeeding syndrome: i. Identify patients at risk (e.g., anorexia, alcohol use disorder, cancer, chronically ill, poor nutritional intake for 1–2 weeks, recent unintentional weight loss, malabsorption). ii. Initially, provide less than 50% of caloric requirements, and then advance over several days to desired goal. iii. Supplement vitamins before initiating PN as well as K+, phosphate, and magnesium (if needed); monitor daily for at least 1 week; and replace electrolytes as needed (many patients will need aggressive electrolyte replacement during the first week of PN). 11. Aluminum toxicity a. More likely to occur in patients receiving long-term PN or in those with renal dysfunction (aluminum is eliminated renally) b. Accumulates in bone and interferes with bone Ca2+ uptake, causing osteopenia c. Neurotoxicity and microcytic anemia d. Contaminates many intravenous electrolytes and intravenous fluids e. Aluminum content documented on drug labels ACCP Updates in Therapeutics® 2023: Pharmacotherapy Preparatory Review and Recertification Course 1-395 Fluids, Electrolytes, and Nutrition 12. H  epatobiliary disorders (includes steatosis, cholestasis, and gallbladder sludge or stones) can occur with long-term PN administration. a. Steatosis (or fatty liver) is associated with overfeeding and a transient elevation in aminotransferase concentration. Although it is usually benign, it can progress to fibrosis or cirrhosis in patients receiving long-term PN. b. Cholestasis usually occurs in children, but it can also occur in adults receiving long-term PN and can progress to cirrhosis and liver failure; a conjugated bilirubin concentration greater than 2 mg/dL is the primary sign. c. Gallbladder stasis is associated with the development of gallstones, sludge, and cholecystitis; it is more attributable to a lack of EN than to PN administration. 13. Osteoporosis and osteomalacia can occur in patients receiving long-term PN, and they are associated with higher protein doses (causes increased Ca2+ excretion) and chronic metabolic acidosis (because of insufficient acetate). Patient Case 9. A 43-year-old male trauma patient (height 75 inches, weight 100 kg) was recently extubated and is receiving PN. His PN formula contains 35 kcal/kg, protein 1.2 g/kg, and dextrose infusing at 4.4 mg/kg/minute, and 25% of total calories as lipid. He has gradually developed symptoms of hypercapnia and has developed a respiratory acidosis. The medical team is considering strategies to correct this to avoid reintubation. Which change to the PN formula could best correct this situation? A. Change PN to EN and maintain current caloric goals. B. Reduce dextrose amount in PN to 3 mg/kg/minute and increase lipid to maintain current caloric goal. C. Change electrolytes to the acetate salt in the PN to correct the acid-base imbalance. D. Reduce the calories to 25 kcal/kg to prevent overfeeding. M. Monitoring patients who are receiving PN 1. Monitor for infection (temperature, WBC, intravenous access site). 2. Monitor for peripheral vein thrombophlebitis or infiltration (if peripheral access); symptoms include pain, erythema, and tenderness or a palpable cord at the site of the peripheral vein; treat by removing catheter. 3. Monitor fluid status (weight, edema, vital signs, input and output, temperature). 4. Monitor nutritional status. a. Prealbumin is useful for monitoring the effects of long-term nutrition support in patients who are not critically ill (see EN Monitoring earlier) because it has a shorter half-life than albumin. i. Values (a) Normal range, 16–40 mg/dL (b) Moderate malnutrition, 11–16 mg/dL (c) Severe malnutrition, less than 11 mg/dL ii. Goal for malnourished patients is an increase of at least 3–5 mg/dL/week until within normal range. b. Serum albumin (normal 3.5–5 g/dL) is a poor predictor of nutritional status because it has a long half-life, and concentrations fluctuate during illness. 5. Monitor for hyperglycemia and hypoglycemia. a. A common blood glucose goal is 140–180 mg/dL. b. Regular insulin (initially 0.05–0.2 units per gram of dextrose) can be added to the PN for patients using a consistent dosage. ACCP Updates in Therapeutics® 2023: Pharmacotherapy Preparatory Review and Recertification Course 1-396 Fluids, Electrolytes, and Nutrition c. 6. 7. 8. 9. For patients with hyperglycemia or fluctuating insulin dosages, insulin can be supplemented separately from the PN, although this practice varies by practitioner. d. Abrupt discontinuation of PN is usually tolerated in patients without diabetes, but rebound hypoglycemia can occur in other patients; avoid by gradually tapering off PN over 1–2 hours. Check blood glucose 30 minutes to 1 hour after discontinuing PN. If PN is discontinued abruptly, rebound hypoglycemia can be avoided by administering 5% or 10% dextrose (may not be necessary if PN is administered through a peripheral catheter). Monitor for electrolyte and acid-base imbalances. The chloride and acetate salts can be adjusted based on the acid-base status of the patient. a. For metabolic alkalosis, Na+ and K+ can be administered as the chloride salts. b. For metabolic acidosis, Na+ and K+ can be administered as the acetate salts (acetate is converted to bicarbonate). c. For respiratory acid-base disorders, correct the underlying cause or adjust the ventilator settings as needed. Monitor triglyceride concentrations and withhold lipids in patients with a concentration greater than 400 mg/dL. When calculating lipid and caloric requirements, account for any drugs mixed in a lipid emulsion (e.g., propofol, clevidipine). Monitor hepatic function. Monitor for patient readiness for oral or EN support. a. Well-nourished, healthy patients can change immediately from PN to oral or EN. b. Older adult, debilitated, or malnourished patients may need a transition period in which oral or EN feedings are gradually increased, coinciding with a reduction in PN. Patient Cases 10. A patient (weight 70 kg) receives propofol at 45 mcg/kg/minute. Propofol is available at a concentration of 10 mg/mL and is mixed in a 10% lipid emulsion. Assuming the patient is receiving this infusion rate for 24 hours, which best approximates the total calories provided by the propofol infusion in a 24-hour period? A. 200 kcal. B. 250 kcal. C. 300 kcal. D. 500 kcal. 11. A  patient (weight 65 kg) is receiving PN after abdominal surgery. The PN contains about 1600 kcal, including 100 g of protein, 500 kcal as lipid, and 200 g of dextrose. The following additives are also included in a 24-hour infusion of PN: sodium chloride 50 mEq, sodium acetate 100 mEq, potassium acetate 60 mEq, sodium phosphate 30 mmol, magnesium sulfate 12 mEq, calcium gluconate 10 mEq/day, multivitamins 10 mL, and trace elements 3 mL. The patient has an NG tube in place that is suctioning 400–500 mL/day, which is being replaced with an infusion of 0.9% sodium chloride. After 48 hours of PN, the patient has the following laboratory values: Na+ 140 mEq/L, K+ 3.8 mEq/L, Cl– 93 mEq/L, serum bicarbonate 35 mEq/L, pH 7.5, PCO2 47 mm Hg, and bicarbonate 36 mEq/L. Which adjustment to the PN formula is best at this time? A. Increase lipids to provide 750 kcal and reduce dextrose to 130 g. B. Increase sodium acetate to 150 mEq/day and discontinue sodium chloride. C. Increase sodium chloride to 150 mEq/day and discontinue sodium acetate. D. Add sodium bicarbonate 50 mEq to PN. ACCP Updates in Therapeutics® 2023: Pharmacotherapy Preparatory Review and Recertification Course 1-397