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Electrolyte Management

Electrolyte Management. Jeff Beamish PGY-3 Intern Bootcamp Lecture Series August 2013. Summary. Hyperkalemia Hyponatremia Hypernatremia Hypokalemia Others: Mg, Phos, Ca (briefly only) Cases.

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Electrolyte Management

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  1. Electrolyte Management Jeff Beamish PGY-3 Intern Bootcamp Lecture Series August 2013

  2. Summary • Hyperkalemia • Hyponatremia • Hypernatremia • Hypokalemia • Others: Mg, Phos, Ca (briefly only) • Cases Disclaimer: this is “boot camp”. I have tried to include the most common issues and management approaches but this lecture was in no way meant to be complete.

  3. Hyperkalemia • Life threatening!

  4. Hyperkalemia My approach: 1) Is it real? -hemolysis, need to be rechecked? -if there is any uncertainty, get an EKG. 2) How aggressive to do I need to be? -Magnitude: K > 6.0 -Rate of change: K yesterday was 3.5 now is 5.5 -EKG findings: peaked T’s, QRS widening

  5. Hyperkalemia

  6. Hyperkalemia 3) Appropriate treatment -Ca Gluconate, 1g over 2-3 min -immediate onset -repeat until EKG normalizes -lasts 30-60 min -D50 1-2 amps + 10U IV insulin: -takes 10-30 min to work -lasts 30-60 min -Lasix (if appropriate) -Kayexalate: 15-30 g q6 -slow onset, requires multiple doses to be effective -in 1 day can reduce K by about 1 mEq/dL -DO NOT USE is post operative patients or if SBO suspected -Dialysis 4) Prevent recurrence, figure out etiology: -Renal failure (acute or resulting from missed RRT) -Medications: ACEi, ARB, K sparing diuretics; digoxin; beta-blockers -Acidosis (remember total body K may be depleted) -Tissue damage -etc…

  7. Hyponatremia: 1) Do first? or think first? • Siezures, altered mental status?  MICU • Otherwise, think… 2) Is it real? Glucose? Other osmotic agents? Lipids? Sorbitol Bladder irrigation? (i.e. what is the likely serum osmolality?) 3) What is the body’s volume status? a) Think: Hypovolemia? CHF? Cirrhosis? Nephrotic syndrome? Other reason why the body might think it is dry? b) check urine osmolarity…

  8. Hyponatremia: 4) Fix the problem: • if hypervolemic: • suggested by hypervolemia on exam and/or high urine osmolarity • optimize fluid status (CHF, Cirrhosis, Nephrotic syndrome) • if euvolemic: • Determine etiology: • Elevated ADH: SIADH, hypothyroid, adrenal insufficiency • Low ADH: beer potomania, polydipsia, tea & toast • Medications: HCTZ • Fluid/free water restriction often first line • SIADH note: remember that if the urine osm > than IVF osms, you will make the hyponatremia worse with fluid

  9. Hyponatremia: 5) Follow up your management: • Goal correction ~0.5 mEq/L/h • That’s no more than 10-12 mEq/L change per day • Ideally aim for an even slower correction < 9 meq/L per day • Complications most common with very low sodium (< 115) for a long time with rapid correction (>10-12 mEq per day)

  10. Hypernatremia: • Does this person need ICU? Significant AMS? Seizures? • Etiology: • Most commonly hypernatremia for impaired access to free water with ongoing water loss: • Example: Elderly pt with on help at home in a hot apartment with diarrhea • Example: Intubated/sedated on tube feeds at an OSH… • Less commonly from diabetes insipidus • Example: psych patient on lithium • Example: post 40 min cardiac arrest in ICU rewarming • Less commonly from osmotic diuresis: • HHS • Workup: check u/a (SG is poor man’s osmolarity) and urine osms.

  11. Hypernatremia: • 3) Treat: • If possible, give oral free water • Remove offending agents, if possible • If this fails:

  12. Hypernatremia: • 3) Treat: • If possible, give oral free water • Remove offending agents, if possible • If this fails: • Calculate the free water deficit • Determine the time needed to correct at 0.5 mEq/L/h • Divide free water deficit by time to estimate D5W infusion rate

  13. Hypernatremia: • 3) Treat: • If possible, give oral free water • Remove offending agents, if possible • If this fails: • The traditional approach involves a simple mass balance on the body and assume essentially no excretion of water or sodium—assumptions that are clearly violated in real life • Does provide a reasonable estimate for starting point: • I’ll do some of the calculations for you: • All have a Na of 155 and your goal is 145: • 50 kg 85 yo woman: 75 cc/h • 70 kg 45 yo man: 145 cc/h • 120 kg 70 yo man: 211 cc/h

  14. Hypernatremia: • 3) Treat: • If possible, give oral free water • Remove offending agents, if possible • If this fails: • Much more important: Pick a reasonable starting rate and CHECK YOUR PROGRESS! • Little old lady: 50-75 cc/h • Normal sized guy: 100-125 cc/h • Big guy: 125-175 cc/h • Repeat labs every 4-8 h depending on severity. Goal correction LESS THAN 0.5 mEq/h. • Pts with DI will need more aggressive volume to meet ongoing losses

  15. Hypokalemia My approach: • What is the degree of change? (<3 requires immediate attention) • What is the Cr? Mg? • Is there an etiology for hypoK (that needs to also be corrected if possible)? • GI losses: Vomiting, diarrhea, NG suction • Renal losses: diuretics, hyperaldosterone • Shifts: acidosis, insulin, adrenergic activity

  16. Hypokalemia My approach: 4) Replete magnesium (goal > 2 for cardiac patients, 1.5-2 for non-cardiac patients—will discuss this in a bit) 5) Replete potassium Normal patient: 10 mEq K increases K by 0.1 mEq/L Maximum K every 4 h is 80 mEq (40 IV, 40 PO)

  17. Hypokalemia My approach: (normal renal function, Mg replete) K = 2.8 Rx: 40 mEq IV now 40 mEq PO q4h x 2 DANGER SUBOPTIMAL GOAL 2 4 3 IV K 40 mEq PO K 40 mEq PO K 40 mEq

  18. Hypokalemia My approach: (normal renal function, Mg replete) K = 3.2 Rx: 40 mEq IV now 40 mEq PO x 1 --OR-- 40 mEq PO q4h x 2 DANGER SUBOPTIMAL GOAL 2 4 3 IV K 40 mEq PO K 40 mEq

  19. Hypokalemia Other considerations: • GFR < 30-40, avoid IV K if possible, give smaller doses, (~50% doses) • ESRD, be very cautious (especially if just dialyzed) • Supplement only to get out danger zone • Use PO K if at all possible • Very cautious with IV K, recheck labs frequently • Account for ongoing losses • Ongoing diarrhea, NG suction • Ongoing diuresis (be mindful of overdiuresis can lead to AKI and hyper K)

  20. Hypokalemia Special cases: ESRD, just dialyzed last night, AM labs K = 2.8 Rx: 20-40 mEq PO discuss higher K bath with renal fellow recheck renal panel 6-12 h DANGER SUBOPTIMAL GOAL 2 4 3 PO K 40 mEq

  21. Hypokalemia Special cases: 55 yo woman with HF exacerbation on lasix gtt 10 mEq/h, normal renal function K = 3.0 Rx: 40 mEq IV, 40 mEq PO q4hx 2 recheck renal panel q12 h, monitor for AKI consider standing K order DANGER SUBOPTIMAL GOAL 2 4 3 PO K 40 mEq IV K 40 mEq PO K 40 mEq PO K 40 mEq

  22. Hypokalemia Special cases: Baseline GFR 30 and stable renal function K = 2.8 Rx: 40 mEq IV, 40 mEq PO q4hx 1 DANGER SUBOPTIMAL GOAL 2 4 3 IV K 40 mEq PO K 40 mEq

  23. Hypokalemia CHECK YOUR WORK!! • Anyone who needs IV K also needs a f/u renal panel at most 12 h later • Everyone is different, adjust repletion based on individual responses

  24. Others…

  25. Hypomagnesemia • Very common • You don’t know it’s not there if you don’t look (I usually check a magnesium level on all pt’s I admit at time of admission) • Cardiac patients: Mg > 2 mg/dL • Toxicity: Mg > 4.8 mg/dl

  26. Hypomagnesemia • Repletion: • Slow… Dangerous peak Renal excretion threshold Mg Wasted Mg Mg t t Infusion time Infusion time

  27. Hypomagnesemia • Repletion: normal renal function, goal 2 • Very rough guidelines: • 1.8-2.0  1 g Mg sulfate / 1h • 1.2-1.7  2 g Mg sulfate / 2h • < 1.2  4 g Mg sulfate or more over 4h or more • If repletion inadequate the next day, try longer infusion time (4g over 12-18 h) • Dose with caution in renal failure, GFR < 30, reduce dose by at least 50% • Oral: magnesium oxide 200-400 mg BID-TID (causes diarrhea)

  28. Hypophosphatemia • Malnutrion, re-feeding syndrome • Normal 2.5-4.9 • Repletion can be given as sodium or potassium salt • IV repletion indicated if Phos < 1.5 • Choose K-phos (contains 1.5 mmol K for each mol phos) or Na-Phos • 2.0-2.5  15 mmol (22 mEq K) • 1.0-1.9  21 mmol (31 mEq K) • < 1.0  30 mmol (45 mEq K) • Often there are shortages: can substitute PO phos, often given every 6 h for a day, then recheck • Potassium acid phos tabs have about 4 mEq K / 500 mg • Must be infused slowly, cannot be infused with calcium • Caution with renal failure.

  29. Hypocalcemia • Correct for albumin (add 0.8 for each g/dL < 4) • Check ionized Ca (need to draw a new sample) • Check RFP, Mg, PTH, 25-OH vit D with iCa • If IV repletion needed (iCa < 1) • 0.85-1  2 g Ca Gluconate over 2h • < 0.85  3 g Ca Gluconate over 3h • Consider etiology • Correct underlying problem Again: caution in renal disease (esp with elevated Phos!)

  30. Hypercalcemia • Correct for albumin (add 0.8 for each g/dL < 4) (it’s probably worse than you think!) • Is acute treatment needed (Ca > 12): • IV hydration 200-300 cc/h initially then adjust to maintain UOP ~ 100-150 cc/h • Lasix AS NEEDED ONLY to maintain euvolemia • For Ca > 14: Calcitonin 4 U/kg SQ q6-12h • Check Ca after 4-6 h and if responding, can continue • Rapid tachyphylaxis develops • Zolendronate 4 mg IV over 15 min • Think about etiology and workup…

  31. Cases: 68 yo man evaluated for jaw pain and difficulty eating found to have. CT neck shows LUL spiculated lung lesion: Na = 126 Cl = 87 Cr = 0.71 Ca = 11.2 Alb = 2.7 Now what?

  32. Cases: 75 yo man admitted to OSH ICU for hepatic encephalopathy. Admission labs notable for elevated ammonia but otherwise unremarkable. He had been in their MICU for 3 d transferred to the floor at the OSH yesterday and now to you on the VA wards. He remains disoriented and minimally responsive on exam. Na = 159 K = 4.2 Cr = 1.2 Now what?

  33. Cases: 56 yo man admitted to ICU after tylenol OD who subsequently develops liver and renal failure, but now transferred to the floor and getting intermittant HD only. Last HD was yesterday. K = 6.0 Now what?

  34. Cases: 57 yo man admitted to the VA for Na 121 on routine labs at a CBOC. It took him all day to get to the hospital. You notice he is a little shaky when you meet him. Now what?

  35. Cases: 55 yo woman with PMH of extensive CAD s/p recent TAH-SAO for large ovarian mass is admitted to CICU POD # 8 for n/v and CP with transient lateral ST depressions K = 2.8 Now what?

  36. Cases: 27 yo woman with h/o of medication non-adherance and DM1 is admitted to UH MICU with DKA. K = 5.8 CO2 = 8, AG 20 BG 423 on arrival What should we do about the K?

  37. Cases: 85 yo woman with h/o diastolic HF transferred to Hellerstein service for placement after aggressive diuresis in the CICU. Continues to look wet, but Cr has been rising over the last 3 days from 1.03.0. She is on a lasix gtt at 10 mg/h. 2 days ago her K was 3.0 and now she is getting standing 40 mEq K each evening while on the gtt. K = 5.2 at 4 AM (not hemolyzed) What should we do about the K?

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