Fluid, Electrolytes, & Nutrition

IV Fluid	Infused Volume	Intervascular Volume Expansion	Fluid Type
Normal Saline	1000 ml	250 ml	crystalloid
Lactated Ringers	1000 ml	250 ml	crystalloid
Normosol and Plasmalyte	1000 ml	250 ml	crystalloid
D5W	1000 ml	100 ml	crystalloid
Albumin 5%	500 ml	500 ml	colloid
Albumin 25%	100 ml	500 ml	colloid
Hydroxyethyl Starch	500 ml	500 ml	colloid

Signs of volume depletion:

• Tachycardia >100 bpm, hypotension, SBP < 80, orthostatic changes, increase BUN:SCr ratio >20:1, dry mucous membranes, decreased skin turgor, reduced urine output, dizziness and improvement in HR and BP after 500-1000 ml fluid bolus.
• Crystalloids are recommended in volume depletion, colloids are not.

Normal Sodium=136-145

Rapid changes in sodium can be life-threatening (demyelination seizures). Correct no more than 10-20 mEq in 24 hours.

Hypernatremia:

• Determine fluid status and correct.
• If acute (occuring over 1-3 days), lower 1-2 mEq/L/h over 24 hours.
• If not acute, correct 0.5 mEq/L/hr over 48 hours.

Hypernatremia:

• 3 % sodium: 100 cc bolus then 100 cc/hr or 1-2 cc/kg/hr to raise 1-2 mEq/hr. CENTRAL LINE ONLY.
• Increase sodium by 2-2.5 for every 100 mg/dL over 100.
• Increase sodium = [(infusate Na) – (Serum Na)] / (TBW +1)

Tolvaptan is discouraged in hyponateriam because hyponateriam returns after it’s discontinued.

Potassium normal: 3.5-5.5

Hypokalemia:

• Mild: 3.0-3.5, moderate: 2.5-3.0, severe=<2.5
• Common causes: thiazide and loop diuretics, kidney injury, GI loss, sweating, burns, Beta blockers, insulin, sodium bicarbonate
• Every 0.3 mEq decrease is a 100 mEq deficit
• Symptoms start at < 3.0
• Correct Mg too. It’s used in potassium transport.
• Seen in EKG as U waves.

Hyperkalemia:

• Arrhythmias when >6.5, peaked T-waves: 5.5-6.5, wide QRS: 6.5-7.5
• Drugs that can cause: ACEI, ARB, Beta blockers, digoxin, triamterene, spironolactone, NSAIDs, renin inhibitors, succinylcholine.
• Treatment:
  • If no EKG changes: insulin and D50.
  • EKG Changes: CaCl or CaGluconate and Insulin and D50 +/- albuterol (increases tachycardia). Calcium stabilizes the cardiac membrane. You don’t need it if not symptoms.
  • Bicarb is useful if acidotic.
  • Kayexeltae isn’t good for acute hyperkalemia, it only decreases K+ by 0.4-1 over 24 hours.
  • In digoxin toxicity, DO NOT GIVE CALCIUM (“stone heart” – but may not really be a risk, don’t give anyway).  Give digibind, and can give dextrose and insulin.

• Increased calcium is often caused by malignancy.
• Calcium regulation is carried by PTH (increases serum calcium, decreases serum phosphate, increases bone resorption) , calcitonin (decreases calcium, decreases bone resorption) and active vitamin D (increases calcium and phosphate, increases bone resorption).  Increases bone resorption = pulls calcium out of the bone, into the blood.
• Hyperparathyroid conditions affect calcium levels

Hypercalcemia:

• Stones (increased calcium increases risk of kidney stones), bones (bone pain, increased resorption from bones), groans (abdominal pain, increased risk of pancreatitis), thrones (polyuria, due to the effects of vasopressin, but increase in ca even more) and psychiatric overtones (depression, confusion, agitation, increase in calcium causes CNS depression, ECG changes: Osborn wave, shortened QT, AV block).
• 40% of calcium is bound to albumin, every 1g/dl decrease in albumin from 4, increase calcium by 0.8.

Treatment:

• IV fluids
• Lasix (can worsen K)
• Calcitonin (inhibits bone resorption, takes 2-3 days)
• IV bisphosphonates (inhibits dissolution and bone resorption, takes 2-4 days with the nadir at 4-7 days).
• If lymphoma – prednisone.
• Severe: Hemodialysis.

Hypocalcemia:

• Calcium chloride vs calcium gluconate:
  • An amp of 10% calcium gluconate contains 8.9 mg/mL of elemental calcium.  An amp of 10% calcium chloride provides a threefold higher concentration of elemental calcium – 27.2 mg/mL.
  •  Calcium chloride is more irritating and is more likely to cause tissue necrosis
  • Calcium gluconate must be hepatically metabolized
  • If calcium gluconate is not available, substitute calcium chloride at one-third of the dose and it is preferable to use central access or a larger catheter in a more proximal site.

Hypomagnesemia:

• Normal magnesium is 1.7-2.3 mg/dl.
• Usually associated with ulcerative colitis, diarrhea, pancreatitis, laxative abuse, inadequate intake, alcohol use, diuretic use, often occurs concurrently with hypocalcemia and hypokalemia.
• Symptoms include tetany, twitching, seizures, arrhythmias, hypertension, and sudden cardiac death.

Treatment:

• Oral supplements
• Symptomatic patients treated with 1-4 mg by IV infusion (1 g/hour to avoid hypotension and increased renal excreation).  Can be pushed in emergencies.
• Reduce dose by half in renal insufficiency.

Hypermagnesemia:

• Usually associated with CKD.
• Symptoms include nausea, vomiting, bradycardia, hypotension, heart block, asystole, respiratory failure, and death.

Treatment:

• Discontinue all magnesium-containing medications
• Asymptomatic people with normal kidney function get 0.9% saline and loop diuretics.
• Symptomatic patients get 100-200 mg of elemental calcium, usually calcium gluconate (see calcium section for gluconate vs chloride) IV over 5-10 minutes (the actions of magnesium in neuromuscular and cardiac function are antagonized by calcium).
• May need hemodialysis in kidney disease.

Hypophosphatemia:

• Normal phosphate: 2.5-4.5 mg/dl
• Usually caused by diuretics, glucocorticoids, sodium bicardbonate, rapidly refeeding patients, respiratory alkalosis, treatment of diabetic ketoacidosis (phosphate shifts into intracellular space)
• Symptoms: hypoxia, confusion, delirium, seizures, coma, respiratory failure, difficulty breathing, heart failure, arrhythmias

Treatment:

• Supplement IV fluid with 10-30 mmol/L of phosphate in patients at risk.
• Oral products (K-Phos) can be used for asymptomatic patients but are poorly absorbed.
• Symptomatic patients receive 15-30 mmol and sometimes 60 mmol of phosphorus IV over 3-6 hours

Hyperphosphatemia:

Typically in patients with chronic kidney disease or hypoparathyroidism. In general, patients are asymptomatic.  See chronic kidney disease for treatment.

They aren’t going to ask you to make a TPN, but here’s some of the most basic info.

TPN Makeup

• Glucose should be 30-70%
• Fat should be 15-30%
• Protein: 1g/kg/day + stress (up to 2)
• Electrolytes
• I remember 50% glucose, 20% fat and 1g/kg of protein.

Caloric requirements:

• The dirty way to calculate caloric needs: 30 kcal/kg/day (+5 if critical, -5 is ok)
• Obtain weight before illness, use if within 20% of IBW. If 20-50% above, feed 25% of fat.
• Real BEE (Basal Energy Expenditure)
  • male:  66+ (13.7 * weight in kg) + (5 * ht in cm) – (6.8 * age)
  • female: 655+ (9.6 * weight in kg) + (1.7 * ht in cm) – (4.7 * age)
• Patient in renal failure need protein restriction unless on dialysis.  They can receive 1.2-1.5 g/kg/day on dialysis.

Calorie Composition:

• Lipids/fats are 9 kcal/g
  • Propofol is 1.1 kcal/mL
• Dextrose is 3.4 kcal/g
• Protein is 4 kcal/g