Electrolytes: Opposites Attract. Brian Dubiel RD, LD, CNSC

Transcription

1 Electrolytes: Opposites Attract Brian Dubiel RD, LD, CNSC

2 Disclosure No conflict of interest exists.

3 Overview Fluids Electrolytes Causes and common treatments for electrolyte abnormalities Shortages Trends Case study

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5 Water 50-60% of body= water age gender weight fat stores Less total body water as we age

6 Fluid requirements Healthy individuals 25-35ml/kg for normal BMI May elect to use ideal body weight for the obese Individuals with high outputs and/or altered organ function should have fluids based on clinical picture. kidney, liver, lung, heart failure Short bowel, high output ostomy/ecf etc.

7 Body Water Compartments Extracellular Fluid Total body water interstitial fluid plasma Intracellular fluid Extracellular fluid

8 Serum Osmolality Measurement of the body electrolyte-water balance. Normal= mOsm/kg H 2 0 Calculating Serum Osmolality= (2 x serum Na) + (BUN/ 2.8) + (blood glucose mg/dl / 18)

9 Composition of common IVF Solution Normal saline (NS) 0.9% Sodium meq/l Chloride Meq/L Potassium Meq/L Lactate Meq/L Dextrose g/l ½ NS Osmolarity mosm/l D5W D5-NS Lactated Ringers (LR)

10 Electrolyte composition of body fluids and equivalent replacement IVF Source Na/L K/L Cl/L HCO 3 /L Equivalent IVF Urine D5-1/2NS, 20meq KCl/L Gastric D5-1/2NS, 10meq KCl/L Duodenum D5-NS Jejunum D5-1/2NS Ileum D5-NS Colon D5-1/2NS, 20meq KCl/L Diarrhea D5-1/2NS, 25meq NaHCO3/L

11 Volume distribution (hypotonic fluid) 1 Plasma 85mL ECF 333mL 1 liter D5W Interstitial 250mL ICF 667mL

12 Volume distribution (Isotonic fluid) 1 1 liter 0.9% NaCl 1000mL ECF 0mL ICF 250mL plasma 750mL interstitial

13 Third spacing Fluid shifts from the plasma or intravascular space to the interstitial or third space. Loss of oncotic and/or hydrostatic pressure Causing edema, effusions, ascites Etiology Severe inflammation, trauma, vein obstruction, intestinal obstruction, etc.

14 Daily Fluid Losses Urine mL GI tract mL Insensible mL (sweat, respiration) Factors increasing fluid losses High stoma OP, emesis, diarrhea Fever Diuresis Burns

15 Case study 50 YO male with normal renal function, afebrile with high ostomy output- 2,300mL daily, 800mL oral fluid intake, 2,000mL IVF +1,500mL for urine +2,300mL for stoma +500mL for insensible losses -800mL oral intake -2,000mL IVF = 1,500mL additional fluid required

16 Antidiuretic Hormone (ADH) Produced by hypothalamus Regulation by osmoreceptors in response to changes in osmolarity Hyperosmolality= ADH released, alerts kidneys to reabsorb water Hypoosmolality= excessive water reabsorption, suppresses ADH release.

17 SIADH Syndrome of inappropriate antidiuretic hormone The body produces too much ADH- fluid retention Common causes Stroke, lung dz, antidepressants, anti seizure meds, CA meds, etc

18 Hypovolemia ECF deficit Without electrolyte loss Dehydration- impaired thirst, inadequate TF flushes, concentrated formula Treat with hypotonic fluid; D5W or increase flushes With electrolyte loss GI losses, aggressive diuresis Results in low urinary Na+ Release of ADH causing fluid retention and often hypona+ 2 Treat with Isotonic fluids with electrolytes

19 Hypervolemia ECF expansion Causes Organ failure, excessive fluid intake, anesthesia Symtoms Edema, SOB, HTN, tachypnea, distended jugular, increased weight Tx Water and/or sodium restriction with/without diuretic use

20 Sodium Major ECF cation Functions to maintain ECF volume and plasma osmolality Regulated by kidney for excretion and reabsorption 23mg=1mEq Na+

21 Hyponatremia Na : nausea, vomiting, weakness, lethargy, headache, altered mental status, muscle cramping, dizziness Na + < 120: seizure, coma, death Sodium correction should not exceed 5 to 10 meq/kg/d to prevent demyelination disorder.

22 Hyponatermia Dilutional (most common) Water restriction Hyperglycemic Pseudo-hyponatremia Decrease of 2.4mEq/L Na+ with every 100mg/dL increase in glucose above normal 3

23 Hyponatremia Hypovolemia Loss of body fluid and sodium Diuresis, excessive GI losses, sweating, burns Tx: Volume expansion with isotonic fluids Hypervolemia Excess body fluid and total body sodium CHF, cirrhosis, nephrotic syndrome, renal failure, heart failure Tx: fluid and Na restriction, treat underlying disorder

24 Hypernatemia Na+ >145 Hypovolemia Loss of total body water Diarrhea, sweating, respiratory, diuresis, renal failure Tx: volume expansion (hypotonic fluids:.45% NS or D5W) Hypervolemia Excessive/normal body fluid with excess total body sodium Aggressive infusion of IV NaCl or Na bicarb Tx: diuretics, water replacement, dialysis

25 Potassium mmol/L Major ICF Cation Functions with metabolism, muscle contraction, cardiac function 1-2mEq/kg/day with normal renal fnx

26 Hypokalemia <3.7mmol/L Causes high gastric losses, alkalosis, hypothermia 2 Aggressive diuretics, beta-agonist bronchodilators 2 Refeeding syndrome Dextrose infusion in malnourished pt> insulin drives K from ECF into cells 5 Symptoms Weakness, muscle spasms, ileus, anorexia Tx Replete magnesium if needed Oral route when possible if asymptomatic IV infusion of KCl 10-20mEq per hour 2

27 K+ wasting medications 6 Acetazolamide Bumetanide Chlorthalidone Ethacrynic acid Furosemide Indapamide Metolazone Thiazides Torsemide Sodium polystyrene sulfonate Phenolphthalein Sorbitol Hydrocortisone Fludrocortisone Prednisone Caffeine Nafcillin Ampicillin Penicillin Aminoglycosides Amphotericin B Foscarnet Theophylline

28 Hyperkalemia >5.1mmol/L Causes Renal failure, K+ supplementation, metabolic acidosis, meds, rhabdomyolysis Symptoms Nausea, fatigue, bradycardia, mental confusion, paresthesia of extremities, cardiac arrhythmia/arrest Tx Dextrose infusion ( g with 5 10 units insulin) 7 Kayexalate, loop diuretic, hemodialysis(renal failure) Severe hyperkalemia >7.0mmol/L +ECG changes; 1g IV Calcium gluconate over 3 mins 2

29 K+ sparing medication 8 ACE inhibitors Angiotensin recptor blockers Beta blockers Cyclosporine Digitalis Diuretics K+ sparing Heparin NSAIDs Pentamidine Penicillin Tacrolimus Trimethoprim-sulfamethoxazole Succinylcholine

30 Magnesium Second most abundant intracellular cation 8-24 meq/day 1g mag = 8 meq Functions Enzymatic reactions, including cellular energy metabolism Maintenance of intracellular potassium and calcium Bone health Absorption: 30 40% Mg absorbed in GI tract Distal jejunum and ileum Excretion: kidneys, stool

31 Hypomagnesemia <1.7mg/dL Causes Urinary losses, alcoholism, diarrhea, refeeding syndrome, diuretics Symptoms Tetany, seizures, altered mental status, arrhythmias Tx Oral preparations for maintenance only 2 (5mg/kg) Slow onset, large doses GI irritant IV given as mag-sulfate 1-2g (8-16mEq) over 1-2 hours

32 Hypermagnesemia >2.6mg/dL Causes Renal disease, excessive supplementation, excessive mag-based antacids Symptoms Altered mental status, hypotension, respiratory paralysis, cardiac arrthymia/arrest Tx Diet restriction Eliminate Mg meds/pn infusion Use diuretics Use IV calcium (1g IV over 2-3 minutes) 9 When severely symptomatic to reverse cardiac and neuromuscular effect

33 Calcium 99% of calcium found in bone Extracellular cation 5-22mEq/day Three forms of serum calcium Complexed to sulfate/phosphate Protein bound (80% on albumin) Ionized (metabolically active) Functions bone health, blood coagulation, neuromuscular function, cell membrane integrity

34 Hypocalcemia <8.5mg/dL Causes Renal failure, hypoparathyroidism, hypomagnesemia, hyperphosphatemia Meds aminoglycosides, cimetidine, heparin and theophylline Symptoms CHF, MS changes, muscle cramps, seizures, double vision, tetany Measuring total serum Ca can be misleading with hypoalbuminemia Serum Ca is decreased Ionized Ca is not changed Using an adjusted calcium equation is not considered accurate 10

35 Hypocalcemia Tx Replete magnesium if needed Asymptomatic replete using oral route ( mg) calcium citrate Symptomatic replete using IV Peripheral 22mL of 10% calcium gluconate over 10 mins Central 8mL of 10% calcium chloride over 10 mins (3x Ca content) 2

36 Hypercalcemia >10.5mg/dL Causes Hyperparathyroidism, malignancy most common Meds lithium, thiazide diuretics Symptoms N/V, constipation, ileus, pancreatitis, hypotension, hypovolemia, confusion Tx (>14mg/dL) IV normal saline to correct hypovolemia IV furosemide 40-80mg q2 hrs with NS to achieve urine OP of mL/hr 2

37 Phosphorus Major intracellular anion Functions Acid-base buffer, cellular & bone fnx Storage and transfer of energy in form of ATP 15-30mmol/day

38 Hypophosphatemia <2.7mg/dL Causes Refeeding syndrome, respiratory alkalosis, DKA, phosphate binders Symptoms Muscle weakness, impaired myocardial contractility, difficulty breathing, seizure, coma Tx IV sodium or potassium phosphate 15, 30 or 45mmol replacements over 4-6 hours ( mmol/kg)

39 Hyperphosphatemia >4.8mg/dL Causes Renal insufficiency/failure, rhabdomyolysis, tumor lysis Symptoms Acute hypocalcemia, formation and deposition of insoluble Calcium phosphate complexes into soft tissues Tx Phosphate binders- aluminum containing antacids, sucralafate, Sevelamer Dialysis

40 Shortages KCl additives/trace element preparations for TPN Change to K-acetate or K-phos MTE 5C exchanged for MTE 4C + 60 mcg selenium IV sodium phosphate Oral given when possible; K-phos IV fat emulsion Adults not given, rationed for peds 1 tablespoon safflower oil orally TID If NPO/SBS administered topically

41 Shortages Amino acids Freamine III 10% Travasol 10% 15% 10% Ethanol lock Reduce to 3 times weekly for high risk patient saline only for lower risk patients

42 Trends Many shortages brought on from Hurricane Maria have resolved Potassium Acetate supply decreased from compensation of KCl shortage. IV famotidine potential for shortage- can be substituted with Ranitidine in TPN

43 Case study 39 YO female with h/o stricturing Crohn s disease and DVT with normal renal fnx. Admitted with SBO. After failing conservative management, OR for SBR with proximal diverting loop ileostomy. On POD#3, diet advanced to clear liquids after ROBF. By POD#4 the patient is noticeably more lethargic and c/o nausea. POD#4 POD#1 Intake POD#4 Sodium 130 meq/dl 138 meq/dl PO 1000 ml Potassium 3.6 meq/dl 3.9 meq/dl IVF/meds 200 ml Chloride 104 meq/dl 96 meq/dl CO2 23 meq/dl 26 meq/dl Output BUN 55 mg/dl 7 mg/dl Urine 900 ml Creatinine 1.86 mg/dl 0.9 mg/dl Stoma 3150 ml Magnesium 1.1 meq/dl 1.6 meq/dl Phosphorus 3.5 mg/dl 1.8 mg/dl Glucose 161 mg/dl 145mg/dl Calcium 8.7 meq/dl 8.5 meq/dl Blood pressure 81/55 118/82 Urine sodium <20 meq/l

44 Poll Question > Answer options on next slide On assessment: Intake<output; oiliguirc Hyponatermic, hypomagnesemic Mildly hypotensive ECF loss + electrolyte loss Which is the best IVF to use for this patient?

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46 Answer is A; isotonic fluid will expand ECF volume

47 Poll question: Which electrolyte should be replaced next? (live poll on next slide)

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49 Answer is D; The magnesium should be repleted before potassium, and since mag is quite low, 2 grams should be infused over 1 hour, especially when symptomatic.

50 References 1. Moukarzel A. Understanding and managing fluid and electrolyte imbalances. In A.S.P.E.N. Core Cirriculum. 2012: Marino P. Hypertonic and Hypotonic Conditions. The Little ICU Book of Facts and Formulas. Lippincott, Williams & Wilkins Ch Hillier TA. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med Apr;106(4): Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21): Stanga Z, et al. Nutrition in clinical practice the refeeding syndrome: illustrative cases and guidelines. Eur J Clin Nutr. 2008;62: Veltri K. Medication Induced Hypokalemia. P&T Mar; 40(3): Kraft M, Btaiche I, Sacks G, Kudsk K. Treatment of electrolyte disorders in adult patients in the intensive care unit. Am J Health Syst Pharm. 2005;63: Salem C, et al. Drug Induced Hyperkalemia. Drug Safety. Springer International Publishing : Modres JP, et al. Excess Magnesium. Pharmacol Rev : Slomp J, et al. Albumin-Adjusted Calcium is Not Suitable for Diagnosis of Hyper- and Hypocalcemia in Critically Ill Patients. Crit Care Med. 2003; 31:

51 Questions?