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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.
Addition of Water Leads to Equilibration Between
Compartments.
Final Distribution is Proportional to
Relative Size of Compartments



                     30
                     28         14
                                15
                                        3 L Water Added

                 +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
 your internship.
…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



      Adrenals                           Aldosterone secretion


                                          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
Renin         ADH
AgII          thirst
Aldosterone
ANP
                                                                 Diarrhea

                                                  Plasma                                        Plasma
                                                  volume                                        osmolality


                         Renal                    Renin
                         sympathetic              secretion                                    ADH secretion
                         activity

                                                Angiotensin II
Direct tubular effect




                                                                     Direct tubular effect
                                                Aldosterone
                                                secretion
                           Renal
                        interstitial
                        hydraulic               Aldosterone                                        ADH
                        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
Effectors          ADH                     ADH
                   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
What about FeNa+?
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
   What about giving half normal
             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
  – High ADH levels
     • CHF
     • Cirrhosis
     • SIADH
                       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

Adults: Meinke: fluid Management in
 Hospitalized patients Comprehensive
 Therapy, vol. 31, no. 3, Fall 2005
             Summary
• Systematic
• Watch serum [Na+]
• Frequent assessment

				
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posted:11/24/2011
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