# IV fluids and you staff washington edu staff washington edu

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IV fluids and you

Michael J Ryan, MD
nephrologist.
Goals
• Review body fluid compartments.
• Review effects of addition of salt, water to
the body
• Cases
TBW = 60% of Body Weight
Or 75 x .6 = 45 Liters

75 Kg    TBW 45 L

2/3rd Inside Cells   1/3rd Outside Cells
 ICF /ICV (30 L)     ECF /ECV (15 L)

ICV         ECV
Distribution of total body water (TBW) between
intracellular and
extracellular spaces

280 mosm/l                  280mosm/l

30 liters                 15 liters

Intracellular                  Extracellular
Distribution of total body water (TBW) in a 75kg man

Intracellular                Extracellular

30 liters                   15 liters

Plasma
Interstitial
Volume
Space 10
4-5
liters
liters
(2/3 of ECV)
(1/3 of
ECV)
COMPOSITION OF FLUID COMPARTMENTS

K K   K   K   K
Na   Na   The predominant solutes in ECV
K K   K   K K Na   Na
& ICV are different.
Na   Na
K K   K   K K
K K   K   K K Na   Na
The predominant solute in ECV
Is Sodium (Na).

The predominant solute in ICV
Is Potassium (K).
What happens if you infuse isotonic
saline into a normal person?
You drink 3 L of water as part of a bet…

Q: What if you add water to a person?
1. Addition of Water or Water Excess

Water Moves Freely Between Two Compartments.
Compartments.
Final Distribution is Proportional to
Relative Size of Compartments

30
28         14
15

+2 L         +1 L
Before…

280 mosm/l        280mosm/l

[K+] = 140 mEq/L   [Na+] = 140 mEq/L

30 liters         15 liters

Intracellular          Extracellular
Case
You decide to go to Mexico prior to starting
…You get diarrhea.

Lots of it…
Q: what does ECV depletion look like?
ICV                            ECV

30 Liters                 15 liters

Normal

Mexico

30 Liters                 10 liters

ECV depletion
ECF depletion
Response to ECV depletion
(Vander, p.119)
Blood pressure

Kidney (JGA)                              Renin secretion

Liver, lung            Plasma angiotensin II concentration

Plasma aldosterone

Kidney (CD)                   Tubular sodium reabsorption
What if it is an osmotic diarrhea,
and you don’t keep up with water
losses?
ICV                       ECV

30 Liters             15 liters

Normal

ICV                      ECV

28 Liters            10 liters

ECV depletion + H2O loss > Na+ loss
(=Hypernatremia)
• How do we measure the ICV of the
patient?
Trick Question!
• We don’t measure the ICV in patients
• We do take note of changes in the size of
the ICV
• ICV is determined by osmolality
• Osmolality in the cell = osmolality outside
the cell
• Na+ is the major determinant of the
extracellular osmolality
• Serum [Na+] indicates changes in ICV
ECF balance   Water balance
AgII          thirst
Aldosterone
ANP
Diarrhea

Plasma                                        Plasma
volume                                        osmolality

Renal                    Renin
activity

Angiotensin II
Direct tubular effect

Direct tubular effect
Aldosterone
secretion
Renal
interstitial
pressure

Tubular Na reabsorption                                    Tubular H2O reabsorption
Volume regulation       osmolality regulation
What is sensed     Effective circulating   Plasma osmolality
volume
Sensor             Carotid sinus           Hypothalamus osmolality
receptor

Afferent glom art.
atria
RAAS
Sympathetic nervous
system
What is affected   Sodium excretion        Water excretion
Water intake            Water intake
How do you measure the ECV?
History
History
How do you measure ECV?
PE.
• Weights
• Posturals
• Neck veins
• Dry axilla
Clinical Guidelines for
Estimating ECV Loss
Na Loss        Symptoms           Labs
Mild          300-450 mEq     BP, -JVP         Hcrit, Alb

(2 - 3 L NS)

Severe        450- 900 mEq  BP, -JVP flat      High BUN/Cr

(3-6 L NS)     Low BP, oliguria

Very severe   > 6 L NS       Shock, anuria      AKI
How best to correct ECV depletion
• Hetastarch?
– May improve physiology in inflammation
– Alslo may adversely affect clotting

– Max recommended dose: 20ml/kg/d
How best to correct ECV depletion
Albumin
• Expensive
• Risk of infection

• Recent meta-analysis: Albumin no better
than crystalloid
saline?
Half-isotonic saline causes both hypo-
osmolality and volume expansion.

Like giving 500 saline, and 500 CC D5W
Who cares?
Hyponatremia is un-good
Hypernatremia - Ungood
• Common
• Iatrogenic
• Mortality increase by 2-7 fold

Snyder, Ann Intern Med. 1987 Sep ;107

Lindner AJKD, 2007
Fluid Management

• General Steps:
– Good History: Hx of Loss of Salt Water,
Weight Loss/Gain (Quantify) etc.
– Review Medications: Diuretic, Lithium etc.
– Good Physical Exam: weights, BP, HR,
Orthostatic Changes, Neck Veins, Chest
Exam, Heart Exam, Presence of Fluid
– Review the Lab Values Carefully
Case
31 year old admitted to the hospital
CC: inability to pass a kidney stone.
Cysto planned for the AM.

PE: normal BP. No edema nl. urine output
[Na+] = 140

NPO after MN.
Q: what IVF do you prescribe?
Usual reasons for IV fluids
1. Defend the normal BP
2. Return the ICF to normal
3. Replace ongoing renal losses
4. Give maintenance fluids to match
insensible losses
5. Glucose as a fuel for the brain
Fluid Management
Specific Steps
1. Assess The Status:
a.   Water
b.   ECV
c.   Acid Base
d.   Potassium
2. Plan Therapy:
a. Basic Allowance
b. Correction
3. Write Orders
1. Assess the status
•   ECV OK?
•   ICV OK
•   Acid base OK?
•   K+ OK?
Fluid Management
Specific Steps
1. Assess The Status:
a.   Water
b.   ECV
c.   Acid Base
d.   Potassium
2. Plan Therapy:
a. Basic Allowance
b. Correction
3. Write Orders
2. Basic allowance
Heat is produced continuously
• Dissipated by evaporation (sweat)

• H2O lost via lungs
Maintenance Fluid Allowance
for Normal ECV State/NPO
Vol (ml)     Na+ mEq K+ mEq Cl- mEq

Urine    1500         50          40           90

S&I      1000         ---------   ----------   --------

----------   ---------   ----------   --------

Total     2500        50          40           90
Basic
Allowance
Plan Therapy

• Correction:
– Correction is to be Slow

– Often Correcting Underlying Problem would
Correct Other Abnormality
• For Example, Correcting NaCl & KCl & Volume
Depletion in Metabolic Alkalosis would also
Correct Metabolic Alkalosis.
Fluid Management
Specific Steps
1. Assess The Status:
a.   Water
b.   ECV
c.   Acid Base
d.   Potassium
2. Plan Therapy:
a. Basic Allowance
b. Correction
3. Write Orders
Basic Allowance & Correction
1.  Basic Allowance:   Vol.   Na+   K+        Cl-
a. Urine            1500    50   40        90
b. S&I              1000
c. G.I.             0
2. Corrections
a. Water           0      0     0     0
b. ECV
c. A/B
Potassium

Total                  2500 50           40         90
Write the order… What solution?

Solution Na+            Cl-            Ca++           HCO3-

Ringers   130           109            2.7            28

NS        154           154

0.45 NS   77            77

0.25NS    38            38

One option - 0.25 NS with 20meqKCl/l 80-100hr.
That’s it!!!
Caveats:
It is important to check the [Na+] frequently
Case
• A Patient Admitted from Nursing Home in a
Confused State. He has been somnolent for 3
days. His BP is normal. There is No Edema,
Lungs are Clear, Heart Normal.
• In Last 24 Hrs. He has made 1 liter of Urine
• His blood test shows:
–   Na 155 mEq/l (Normal 135 – 145)
–   Blood Glucose Normal (80 mg/dl)
–   K Normal (4.0), HCO3 Normal (28), Cl (117)
–   Anion Gap Normal (155 – (117 + 28) = 10
Fluid Management
Specific Steps
1. Assess The Status:
a.   Water
b.   ECV
c.   Acid Base
d.   Potassium
2. Plan Therapy:
a. Basic Allowance
b. Correction
3. Write Orders
Case
24 year old woman develops UTI.
She treats it with cranberry juice.
Then develops fever chills flank pain.
Her friends told her to drink lots of water.

PE: 100/60 HR 110.
No postural changes.
[Na+] = 130
Fluid Management
Specific Steps
1. Assess The Status:
a.   Water
b.   ECV
c.   Acid Base
d.   Potassium
2. Plan Therapy:
a. Basic Allowance
b. Correction
3. Write Orders
Who shouldn’t get hypotonic fluid?
• Patients with [Na+] <138
• Patients at risk for hyponatremia
• CHF
• Cirrhosis
Case
55 year old with post op paralytic ilius.
24 hour Intake and output:
NG:             2000ml
Urine output 400ml
[Na+]           140
HCO3-           24.

Q: what fluids?
Concentration of stuff in NG output
Vol (ml)   Na+ mEq   K+ mEq   Cl- mEq
1000       100       10       110
Basic Allowance & Correction
1.  Basic Allowance:   Vol.   Na+   K+   Cl-
a. Urine            1500    50   40   90
b. S&I              1000
c. G.I.             2000   200   20   220
2. Corrections
a. Water
b. ECV
c. A/B
Potassium

Total                  4500 250     60   310
• 0.45 NS with 10meq KCl/l @ 185cc/hr
References
Pediatrics:
Roberts KB: Fluid and electrolytes:
parental fluid therapy
Pediatrics in Review vol 22 11 2001

Hospitalized patients Comprehensive
Therapy, vol. 31, no. 3, Fall 2005
Summary
• Systematic
• Watch serum [Na+]
• Frequent assessment

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 views: 17 posted: 11/24/2011 language: English pages: 60