FLUIDS AND ELECTROLYTES

Sam Lai, MD July 2016 “A d a p t e d ” f r o m Bindu Swaroop, MD William Graham, MD

F/E: OBJECTIVES  Understand replacement strategies for common electrolytes    

Potassium Magnesium Phosphorus Calcium

 Know the common clinical manifestations of electrolyte disturbances

 Know the common causes of electrolyte disturbances

F/E: OVERVIEW Mr. Frodo, a 60 y/o male from New Zealand with no significant medical history, presents to the UCI ER for increased fatigue and lethargy. He is noted to have dry mucous membranes and, although he denies any medication usage, in his knapsack is a prescription for Lasix. His K is found to be 3.0. The intern on call, Dr. Acula, stops his Lasix and decides to replace his potassium. 1. What are other manifestations of hypokalemia? 2. What are the most common causes of hypokalemia? 3. How do you replace potassium?

F/E: HYPOKALEMIA 1 . Clinical manifestations of hypokalemia?  Cardiac  AV block, PAC, PVC, Vtach/Vfib

 MSK  Ascending weakness  Rhabdomyolysis (vasoconstriction during exercise)

 GI  Nausea/vomiting

F/E: HYPOKALEMIA 2. What are the most common causes of hypokalemia?

 GI/GU losses  Diuretic usage  Diarrhea

F/E: HYPOKALEMIA 3. How do you treat hypokalemia?  Oral:

0.1 increase in serum K for each 10 meq given

 Potassium Chloride (most common formulation)  Usually patients are also hypochloremic and alkalotic  Can be liquid or pill form

 Potassium Phosphate (if concomitant hypophosatemia)

 IV  Potassium Chloride  Can be painful if infusion through a peripheral vein

(Goal K – Serum K) Serum Creatinine

F/E: CONTINUED Mr. Frodo, a 60 y/o male from New Zealand with no significant medical history, presents to the UCI ER for increased fatigue and lethargy. He is noted to have dry mucous membranes and, although he denies any medication usage, in his knapsack is a prescription for Lasix. His K is found to be 3.0. The intern on call, Dr. Acula, stops his Lasix and decides to replace his potassium. How would you treat his potassium deficit?

F/E: CONTINUED Dr. Acula checks on Mr. Frodo after 4 hours and, while checking his blood pressure, he notices that Mr. Frodo’s hand starts to curl and twist. He starts to mumble… “I won’t make it Sam…. Sam…..”. Repeat BMP shows K of 2.8.

1. What are the common manifestations of hypomagnesemia? 2. What are some common causes of hypomagnesemia? 3. How do you replace magnesium?

F/E: HYPOMAGNESEMIA 1 . What are the common manifestations of hypomagnesemia?  Neuromuscular  Tetany (Trousseau’s and Chvostek’s sign)  Seizures  Delirium

 Cardiovascular  Widening QRS  Torsades

 Electrolytes  Hypokalemia  Luminal transporters on the collecting ducts are inhibited by magnesium  Low magnesium allows high intracellular potassium to efflux in to the urine

F/E: HYPOMAGNESEMIA 2. What are the most common causes of hypomagnesemia?  GI/GU losses  Chronic diarrhea  Chronic diuretic usage

F/E: HYPOMAGNESEMIA 3. How do you replace magnesium?  Oral (Each has 60-80 mg of elemental magnesium)  Take 3 tabs/day for mild, 6 tabs/day for moderate  Magnesium Chloride  Mag-Tab SR 0.5 increase for 2g given

 IV

 If Mg < 1 mg/dL  8 grams over 12 hours  If Mg 1 - 1.5 mg/dL  4 grams over 6 hours  If Mg 1.5 – 2 mg/dL  2 grams over 2 hours

F/E: CONTINUED Dr. Acula checks on Mr. Frodo after 4 hours and, while checking his blood pressure, he notices that Mr. Frodo’s hand starts to curl and twist. He starts to mumble… “I won’t make it Sam…. Sam…..”. Repeat BMP shows K of 2.8. Mg shown to be 1 .4 How would you treat his hypomagnesemia?

F/E: CONTINUED After his brief blood break, Dr. Acula walks by Mr. Frodo’s telemetry and notices a prolonged QT interval. While checking on Mr. Frodo, he notices some mild muscle twitching. Mr. Frodo asks him “Where have you taken it? It’s MINE!” His repeat BMP shows normal K and Mg, but calcium of 7.0. 1. What are the common manifestations of hypocalcemia? 2. What are some common causes of hypocalcemia? 3. How do you replace hypocalcemia?

F/E: HYPOCALCEMIA 1 . What are the common manifestations of hypocalcemia?  Neuropsychiatric  Tetany, Seizures  Hallucinations and frank psychosis

 Cardiovascular    

Hypotension Heart Failure Prolonged QT Arrhythmia

F/E: HYPOCALCEMIA 2. What are some common causes of hypocalcemia?  Electrolytes  Hyperphosphatemia  Hypomagnesemia  Inhibits PTH secretion in response to hypocalcemia

 Vitamin D resistance/deficiency  Primary PTH disorders  Surgery  Autoimmune

F/E: HYPOCALCEMIA 3. How do you replace hypocalcemia?  Oral (~ 1000-1200 mg elemental calcium/day)  Calcium Carbonate  Calcium Citrate

 IV (symptomatic or < 7.5 mg/dL)  Calcium Gluconate (1-2g over 20 minutes)  Calcium Chloride (can cause tissue necrosis)  Must treat with slow infusion afterwards

0.5 increase for 1 g given

F/E: CONTINUED After infusing Mr. Frodo with calcium, Dr. Acula goes to his coffinlike sleep-room. Nurse Weasley pages him a few minutes later, just as he’s about to fall asleep. “Hey doctor, Mr. Frodo in room 9 ¾ can’t breathe, just FYI” Labs show Phosphorus of 1 mg/dL 1. What are the common manifestations of hypophosphatemia? 2. What are some common causes of hypophosphatemia? 3. How do you replace hypophosphatemia?

F/E: HYPOPHOSPHATEMIA 1 . What are the common manifestations of hypophosphatemia?  Lungs  Respiratory failure from diaphragm weakness

 MSK  Rhabdomyolysis  Dysphagia

 Neuro  Paresthesia or confusion

F/E: HYPOPHOSPHATEMIA 2. What are some common causes of hypophosphatemia?  Refeeding syndrome  Malabsorption  Vitamin D deficiency  Chronic diarrhea

 Increased urinary excretion  Primary/Secondary Hyperparathyroidism

F/E: HYPOPHOSPHATEMIA 3. How do you replace hypophosphatemia?  Oral  Sodium-Phos (tab/powder, each one = 250 mg or 8 mmol)

 IV  Sodium Phosphate IV  If Phos > 1.3 mg/dL  0.2 mmol/kg over 6 hours  If Phos < 1.3 mg/dL  0.4 mmol/kg over 12 hours

FLUIDS: OVERVIEW Mr. Frodo returns to UC Irvine and is found to have abnormal CXR and CT Chest concerning for malignancy. He is NPO after midnight for possible bronch and biopsy. He weighs 85 kg. As Mr. Frodo is a bounce-back admission, Dr. Acula places him on D5 ½ NS @ 75 mL/hr Is that the right rate?

FLUIDS: OBJECTIVES  Understand the basics of fluid distribution  Understand daily fluid and electrolyte requirements  Dif ferentiate between dif ferent fluid preparations  Maintenance versus Repletion  Know the basic distribution of a fluid bolus

FLUIDS: BASICS

Total Body Water

Extracellular Fluids (1/3 of TBW)

Intracellular Fluids (2/3 of TBW) Interstitial Fluid (2/3 of ECF)

Intravascular Fluid (1/3 of ECF)

FLUIDS: TOTAL BODY WATER Total Body Water Weight (kg) x 0.6 (Male) or 0.5 (female) Example:  70 kg male  TBW = 70 kg x 0.6 = 42 Liters

FLUIDS: BASICS 70 kg male

Total Body Water 42 L Extracellular Fluids 14 L

Intracellular Fluids 28 L Interstitial Fluid 11 L

1/4 Intravascular Fluid 3L

FLUIDS: OBJECTIVES  Understand the basics of fluid distribution  Understand daily fluid and electrolyte requirements  Dif ferentiate between dif ferent fluid preparations  Maintenance versus Repletion  Know the basic distribution of a fluid bolus

FLUID: DAILY  MINIMAL Daily Water output:    

Urine: 500 mL Skin: 500 mL Respiratory: 400 mL Stool: 200 mL

OUTPUT = 1600 mL

 MINIMAL Daily Water input  Ingested: 500 mL  Water Content, Food: 800 mL  Water Oxidation: 300 mL

INPUT = 1600 mL

Fever? Average adult  35 mL/kg/day GI Loss?

FLUIDS: OBJECTIVES  Understand the basics of fluid distribution  Understand daily fluid and electrolyte requirements  Dif ferentiate between dif ferent fluid preparations  Maintenance versus Repletion  Know the basic distribution of a fluid bolus

FLUIDS: T YPES Na (mEq/L)

K (mEq/L)

K (mEq/L)

HCO3 (mEq/L)

D5W ½ NS

77

77

D5 ½ NS

77

77

NS

154

154

D5NS

154

154

LR

130

4

109

Dextrose (gm/L)

Osmolality (mOsm/L)

50

278 154

50

432 308

28

50

586

50

272

FLUIDS: T YPES Na (mEq/L)

K (mEq/L)

K (mEq/L)

HCO3 (mEq/L)

D5W ½ NS

77

77

D5 ½ NS

77

77

NS

154

154

D5NS

154

154

LR

130

4

109

Dextrose (gm/L)

Osmolality (mOsm/L)

50

278 154

50

432 308

28

50

586

50

272

FLUIDS: T YPES Na (mEq/L)

K (mEq/L)

K (mEq/L)

HCO3 (mEq/L)

D5W ½ NS

77

77

D5 ½ NS

77

77

NS

154

154

D5NS

154

154

LR

130

4

109

Dextrose (gm/L)

Osmolality (mOsm/L)

50

278 154

50

432 308

28

50

586

50

272

FLUIDS: T YPES Na (mEq/L)

K (mEq/L)

K (mEq/L)

HCO3 (mEq/L)

D5W ½ NS

77

77

D5 ½ NS

77

77

NS

154

154

D5NS

154

154

LR

130

4

109

Dextrose (gm/L)

Osmolality (mOsm/L)

50

278 154

50

432 308

28

50

586

50

272

FLUIDS: T YPES Na (mEq/L)

K (mEq/L)

K (mEq/L)

HCO3 (mEq/L)

D5W ½ NS

77

77

D5 ½ NS

77

77

NS

154

154

D5NS

154

154

LR

130

4

109

Dextrose (gm/L)

Osmolality (mOsm/L)

50

278 154

50

432 308

28

50

586

50

272

FLUIDS: OBJECTIVES  Understand the basics of fluid distribution  Understand daily fluid and electrolyte requirements  Dif ferentiate between dif ferent fluid preparations  Maintenance fluid calculation  Know the basic distribution of a fluid bolus

FLUIDS: MAINTENANCE

 What is the goal of maintenance fluid?  Replace ongoing losses of water/electrolytes under normal conditions  Such as when patient is not eating and afebrile

FLUIDS: MAINTENANCE 3 ways you can calculate rate  Use hard math 

35 mL/kg/day x weight (kg)

 Use easier math: “4-2-1 rule”  4 mL/kg/hr for first 10 kg  2 mL/kg/hr for next 10 kg  1 mL/kg/hr for remaining weight

 Use easiest math!  Weight (kg) + 40

FLUIDS: MAINTENANCE Mr. Frodo returns to UC Irvine and is found to have abnormal CXR and CT Chest concerning for malignancy. He is NPO after midnight for possible bronch and biopsy. He weighs 85 kg. As Mr. Frodo is a bounce-back admission, Dr. Acula places him on D5 ½ NS @ 75 mL/hr Is that the right rate?

FLUIDS: MAINTENANCE

Is that the right rate?   

Weight (kg) + 40 85 kg + 40 125 mL/hr

FLUIDS: MAINTENANCE After his biopsy by Dr. Dumbledore, the patient spikes a temperature to 103 F, HR 110 and BP 80/60. Dr. Acula decides to initiate fluid resuscitation with 2L of ½ NS. Is this the right fluid solution?

FLUIDS: OBJECTIVES  Understand the basics of fluid distribution  Understand daily fluid and electrolyte requirements  Dif ferentiate between dif ferent fluid preparations  Maintenance versus resuscitation  Know the basic distribution of a fluid bolus

FLUIDS: CONCEPTS

CONCEPTS Free water is essentially distributed across all compartments Sodium is essentially confined in the extracellular space Remember the 2/3 and 1/3, then ¾ and ¼ rule for fluids

FLUIDS: WHERE’S THE BOLUS GOING? 1000 mL D5W distributed into Total Body Water

Interstitial 255cc

Intravascular

85cc (8.5%)!!

FLUIDS: WHERE’S THE BOLUS GOING? Free water content

ICF

ECF

Interstitial

Intravascular

D5W

1000 mL

660 mL

340 mL

255 mL

85 mL (8.5%)

½ NS

500 mL

500 mL

670 mL

500 mL

170 mL (17%)

NS

0

0

1000 mL

750 mL

250 mL (25%)

FLUIDS: WHERE’S THE BOLUS GOING? Free water content

ICF

ECF

Interstitial

Intravascular

D5W

1000 mL

660 mL

340 mL

255 mL

85 mL (8.5%)

½ NS

500 mL

500 mL

670 mL

500 mL

170 mL (17%)

NS

0

0

1000 mL

750 mL

250 mL (25%)

Normal saline has no free water and is confined to ECF space; this is why it is the preferred IVF for resuscitation!

FLUIDS: THE END Mr. Frodo goes home to New Zealand. Dr. Acula follows up with him in a few days and tells him the good news! The mass was just a metal ring and the doctors threw it away.

FLUIDS: THE END It also turns out the hospital has had multiple units of blood missing from the blood bank.

Dr. Acula Dracula

FLUIDS: SUMMARY

 Assess DAILY the need for fluids  Choose fluids based on weight  Remember the 1/3 and 2/3 rule!  Recognize the concentration of solutes in each fluid