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Fluids and Electrolytes

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Fluids and Electrolytes Elizabeth A. Beierle Tad Kim, M.D. UF Surgery tad.kim_at_surgery.ufl.edu (c) 682-3793; (p) 413-3222 Overview Fluid Compartments in the body ... – PowerPoint PPT presentation

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Title: Fluids and Electrolytes


1
Fluids and Electrolytes
  • Elizabeth A. Beierle
  • Tad Kim, M.D.
  • UF Surgery
  • tad.kim_at_surgery.ufl.edu
  • (c) 682-3793 (p) 413-3222

2
Overview
  • Fluid Compartments in the body
  • Revisiting Volume of Distribution
  • Determining distribution of various fluid types
  • Fluids for maintenance
  • Derived from
  • Fluid requirements per day
  • Electrolyte requirements per day
  • Fluids for resuscitation
  • A case of electrolyte abnormality

3
Fluid Compartments
  • Total Body Water (TBW) 0.65 x Wt male
  • 0.5 x
    Wt female
  • Intracellular Fluid (ICF) 2/3 TBW
  • Extracellular Fluid (ECF) 1/3 TBW
  • Interstitial Fluid (ISF) 2/3 ECF
  • Intravascular Fluid 1/3 of ECF

4
Exercise in Fluid Compartments
  • 70kg Male
  • What is his approximate blood volume?
  • TBW 0.65 x 70kg 45L
  • ECF 1/3 x TBW 15L
  • Blood volume 1/3 x ECF 5L
  • Typical vascular volume is 5L
  • Remember Blood volume 1/9 of TBW or 1/3 of
    ECF. ECF is 1/3 of TBW

5
Distribution of Various Fluids
  • Membrane barriers btw compartments
  • Infusions are introduced into plasma / vessel
  • Will distribute until impermeable barrier
  • Plasma Interstitial fluid separated by
    capillary endothelium permeable to all ions, but
    not to plasma proteins (i.e. albumin)
  • Albumin will stay intra-vascular
  • ECF ICF separated by cell membrane impermeable
    to electrolytes
  • electrolytes will distribute throughout ECF
  • TBW free water, urea distribute everywhere

6
Distribution of Various Fluids
  • Give a 70kg male 3L of Free water
  • Will distribute throughout TBW (Vd 45L)
  • Hematocrit will drop only 3/45th (hemodilution)
  • Give a 70kg male 3L of NS
  • Will distribute throughout ECF (Vd 15L)
  • Hematocrit will drop 3/15th or 1/5th
  • 70kg male loses 1L of blood, why do you give 3L
    NS? (Why the 31 rule?)
  • Because 3L NS will distribute throughout ECF
  • Plasma is 1/3rd of ECF, so effectively only 1/3rd
    of that NS will distribute to the plasma

7
Distribution of Various Fluids
  • So if a 70kg male (with TBW 45L) lost 1L of
    blood, how much to replace using
  • Free water? (Recall Plasma is 1/9 of TBW)
  • Takes 9L free water to replace 1L of plasma
  • NS? (Recall 3-to-1 rule Plasma is 1/3 ECF)
  • Takes 3L of NS to replace 1L of plasma
  • Albumin? or Blood? (11 replacement)
  • Takes 1L of 5 albumin or 3 Units 1L PRBC
  • ½ NS?
  • Takes 3L of NS, so it should take 6L of ½ NS
  • Dextrose is not considered for resuscitation

8
Fluids for Maintenance
  • D5 ½NS 20KCl
  • What does this mean?
  • D5 5 glucose 5g dextrose per 100mL of
    solution or 50g per Liter bag
  • Prevents mobilization of protein as fuel source
  • NS 154mEq Na 154mEq Cl per Liter
  • 20KCl 20mEq KCl per 1L bag

9
Fluid Requirements per day
  • 100 / 50 / 25 or the 4 / 2 / 1 rule (per hour)
  • First 10kg ? 4mL/kg/hr
  • 10-20kg ? 2mL/kg/hr
  • gt20kg ? 1mL/kg/hr
  • Easy way to remember
  • At 10kg, you need 40mL/hr
  • At 20kg, you need 60mL/hr
  • Anything over 20kg, its 60 (1 per extra kg)

10
Exercise in Maintenance Reqs
  • 50kg ? 60 (difference btw 50 20)
  • 60 30 90mL/hr maintenance fluids
  • 70kg ? 60 (difference btw 70 20)
  • 60 50 110mL/hr
  • 100kg ? 60 (difference btw 70 20)
  • 60 80 140mL/hr
  • 15kg ? 40 2x (difference btw 15 10)
  • 40 10 50mL/hr

11
Electrolyte Requirements
  • For Adults
  • Sodium 2-3mEq/kg/day
  • Chloride similar to sodium
  • Potassium 0.5-1mEq/kg/day

12
Review of Fluids/Lytes Reqs
  • 70kg patients requirements
  • Maintenance IVF 110mL/hr 2.5L/day
  • Sodium Needs 140-210mEq/day
  • Potassium Needs 35-70mEq/day

13
Revisit Why D5 ½NS 20K?
  • 70kg ?
  • Needs 2.5L/day of D5 ½NS 20K
  • ½ NS 77mEq Na per L
  • 2.5 x 77 190mEq Na (falls in the 140-210 range)
  • 20K 20mEq KCl per L
  • 2.5 x 20 50mEq K (falls in the 35-70 range)

14
Infants
  • Same maintenance rate requirements
  • Slightly altered electrolyte needs
  • Sodium ? 3-5mEq/kg/day
  • Chloride ? similar
  • Potassium ? 1mEq/kg/day

15
Review in 10kg infant
  • 10kg infant
  • Maintenance Needs 40mL/hr 1L/day
  • Sodium Needs 30-50mEq/day
  • Potassium Needs 10mEq/day

16
Why use D5 ¼NS 10K?
  • 10kg ?
  • Needs 1L/day of D5 ¼NS 10K
  • ¼NS 39mEq sodium (falls in 30-50 range)
  • 10K 10mEq potassium (exactly right)
  • Around 10kg is the cutoff after which you can use
    adult-type maintenance fluids

17
Fluids for Resuscitation
  • For hypovolemic or dehydrated patients
  • Vomiting, sepsis, pancreatitis, burns, etc
  • Signs dry mucous membranes, poor skin turgor,
    skin tenting, no axillary sweat, pt is thirsty,
    weight loss
  • Tachycardia (before hypotension), oliguria
  • This is the C in ABCs
  • 2 large bore IVs, Foley and continuous monitor
  • Isotonic crystalloid fluids (LR, NS, plasmalyte)
  • Bolus IVF 20mL/kg in peds, 2L in adults
  • Assess response and re-bolus until patient
    responds. If no response, then think fast about
    reasons for hypoTN (tension, tamponade, bleed)

18
Case
  • 6wk old baby presents with projectile nonbilious
    emesis after meals, then is immediately hungry.
  • Palpable olive on exam of epigastrum
  • Ultrasound 4mm pyloric muscle thickness
  • What is the diagnosis?
  • What is the metabolic/electrolyte abnormality
    associated with this dx?
  • What is the management?

19
Case
  • Dx Hypertrophic pyloric stenosis (HPS)
  • Metabolic abnormality
  • Hypochloremic, hypokalemic metab alkalosis
  • Lose chloride when vomiting
  • Proximal convoluted tubules (PCT) reabsorb sodium
    w chloride to preserve volume
  • Runs out of chloride, reabsorbs bicarbonate
  • More Na delivered distally b/c above is limited
  • Aldosterone acts to promote Na/K exchange
  • Lose potassium, then K/H exchange gt lose H

20
Case
  • Metabolic disturbance due to volume depletion in
    the face of hypochloremia
  • Management of HPS
  • D5 ½ NS 20K _at_ 1.5-2x maintenance
  • Alkalosis resolves via both volume repletion and
    chloride replacement
  • Alkalosis is a/w ?risk of post-op apnea, so you
    must correct alkalosis before OR
  • Pyloromyotomy laparoscopic vs open

21
Take Home Points
  • Understand body compartments
  • Understand volume of distribution of types of
    fluids crystalloid vs colloid vs free water
  • Be able to figure hemodilution after fluids
  • Justify the use certain maintenance IVF
  • Know what fluids are for resuscitation
  • Understand the metabolic derangement of HPS and
    its treatment
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