Fluids and Electrolytes

1. Fluids and Electrolytes Roy R. Danks, DO, FACOS

2. Objectives Review commonly used intravenous fluids and their compositions Review indications for fluid adjustments Review common electrolyte derangements and how to correct them

3. Body Water • 50-70 % of the body is water • More muscle = more water • Males = more water • Decreases with age • About 2/3 of this water is found within the cells (intracellular)…depending on the source you read

4. How much does your patient need? • 35 mL/kg/day • GI “turn over” • 6000 – 9000 mL/day • 200-400 mL/day lost in stool • Renal • 1000 – 1500 mL/day • Insensible losses • 600 – 800 mL/day

5. Increased Needs • Fever • 10-15% increase needed for each 1 degree C increase in temperature • Tachypnea • 50% increase or each doubling of RR • Evaporation • Sweating, vent and open abdomen • GI • Fistula, diarrhea and T-tube • Operative • 600 – 1000 mL/hr in major abd operations

6. IV Fluids

8. Sodium • The major determinant of tonicity • It’s the primary extracellular cation • Adults need 100-150 mEq/day • Primary organs for regulation: • Kidneys • Pituitary (ADH [posterior pituitary]) • Adrenals (Aldosterone [adrenal cortex])

9. Sodium • Assuming normal water content • Low plasma volume  low BP  Angiotensin II • Angiontensin II  Thirst + Aldosterone • Aldosterone  Resorption of sodium Salt excess? • Plasma osmolality increases  ADH released • ADH release  water retention

11. Hyponatrema

12. Potassium • Critical for glucose transport, intracellular protein deposition and myoneural conduction • One of 2 major intracellular cations • The other is….? • Serum levels do not reflect intracellular values • 1 mEq/L ECF = 200 mEq/L ICF • Affected by: Acid base balance, Na metabolism, nutritional state, renal ftn and diuretics

13. Potassium • Daily requirements • 50 – 100 mEq/day (adult) • More is needed when pts are on NG suction and/or K+ losing diuretics (the loop diuretics)

14. Derangements of K+ • HypoK+ • Replace based on serum value • Manage with constant infusion of IVF • Identify cause(s) of ongoing losses • Salivary: 20-30 mEq/L (1-2 liters/day) • Stomach: 0-30 mEq/L (up to 4 L/day) • Colon: 30 mEq/L

15. Derangements of K+ • HyperK+ • Leukocytosis, hemolysis and thrombocytosis will cause a pseudohyperkalemia • Acidosis, hypoinsulinism, tissue necrosis, reperfusion and dig toxicity (redistributional) • Renal insufficency, excessive intake, mineralocorticoid deficiency, diabetes and spironolactone use (elevated total body K+)

16. Treatment of HyperK+ • Remove exogenous source • For critically high (>7.5 mEq/L or EKG changes) • Calcium gluconate: 1 gm over 2 min IV • Sodium bicarb: 1 amp IV • D50, 1 amp + 10 units of regular insulin • Emergent dialysis • Hydrate and force diuresis • Kayexalate 20-50 gm in 200 mLsorbitol PO and repeat every 4 hrs as needed

17. Calcium We store it! It’s often low in our malnourished patients Usually asymptomatic until <8 mEq/L Look for neurologic signs Use ionized Ca++ over serum Ca++ for day to day management

18. Hypocalcemia Calcium chloride or gluconate IV Chronic low Ca++?: tums, OsCal, etc Phosphate binding antacids improve Ca absorption Add Vit D once phos is normal

19. Hypercalcemia Most often due to malignancy or hyperparathyroidism Also: thiazides, mild-alkali syndrome, granulomatous dz, acute AI, hyperthyroidism, prolong immorbilization, Pagets disease First! Check PTH Treat: Hydrate, loop diuresis, steriods and a medicine consult

20. Magnesium Check it just like all your electrolytes Very often will find it to be low Replace with 1-2 gm per day, IV Low Mg will cause arrhythmias, so when your patient’s develop these post op….