1. Principals of fluids and electrolytes management
Ram Elazary, MD
General Surgery Department
Hadassah Hebrew University Medical Center
Campus Ein-Kerem, Jerusalem

2. Total Body Water body weight% Total body water% Total 60 100
Intracellular 40 67
Extracellular 20 33
Intravascuar 5 8
Interstitial 15 25

3. Composition of Fluids plasma interstitial intracellular CationsNa K Ca
Mg 2 1 7
Anions Cl
HCO SO
HPO
Protein

4. Control of Volume
Kidneys maintain constant volume and composition of body fluids
Filtration and reabsorption of Na
Regulation of water excretion in response to ADH
Water is freely diffusible
Movement of certain ions and proteins between compartments restricted

5. Control of Volume Effective circulating volume Third space loss
Portion of ECF that perfuses organs
Usually equates to Intravascular volume
Third space loss
Abnormal shift of fluid for Intravascular to tissues eg bowel obst, i/o, pancreatitis

6. Normal Water Exchange Mean daily (ml) Minimal daily (ml)
Sensible Urine Intestinal up to liters Sweat up to liters 500
Insensible Lungs/Skin
( 10%/1 o rise in Temp)

7. Normal source of water ~2000ml - 1300 free water intake
700 bound to food
additional water from catabolism

8. Water and Eletrolytes Exchange
Surgical patients prone to disruption:
NPO
anaesthesia
Trauma (surgery)
sepsis

9. Fluid and Electrolytes Therapy
Surgical patients need:
Maintenance volume requirements
On going losses
Volume excess/deficits
Maintenance electrolyte requirements
Electrolyte excess/deficits

10. 1. Volume Deficit vital signs changes
Blood pressure
Heart rate
CVP
Peripheral temperature and capillary filling time
urine output low

11. 1. Volume Deficit Decreased skin turgor Sunken eyes Oliguria
Orthostatic hypotension
High BUN/Creatine ratio
Plasma Na may be normal

12. Fluids resusitation Adults: 1000 ml Pediatrics: 20 ml/kg
Fluids of crystaloids (NS or RL)
Repeated dose

13. 2. Maintenance Requirements
This includes: insensible loss
urinary
stool losses
Body weight Fluid required 0-10Kg 100ml/kg/d next 10-20Kg 50 ml/kg/d subsequent Kg ml/kg/d 15ml/Kg/d for elderly

14. 70 Kg Man Needs 1st 10kg x 100mls = 1000mls 2nd 10kg x 50mls = 500mls
Next 50kg x 20mls= mls
TOTAL mls /d

15. Maintenance Electrolyte Requirements
Na 1-2mEq/Kg/d K mEq/Kg/d
Usually no K given until urine output is adequate
Always give K with care, in an infusion slowly - never bolus (max 0.2% KCL through peripheral IV)

16. Na 1gr = 17 mEq
K 1gr = 13.6 mEq
70 Kg H2O 2500ml
Na 70*2 =140 mEq = ~ 9gr
K 70*1 =70 mEq = ~ 5gr
NS %KCl 100ml/h

17. fluids composition

18. 3. On Going Losses
NGT
drains
fistulae
third space losses

20. 4. Volume Excess Over hydration Mobilization of third space losses
Signs
weight gain
pulmonary edema
peripheral edema
S3 gallop

21. Fluid and Electrolyte Therapy
Goals
normal hemodynamic parameters
normal electrolyte concentration
Method
replace deficits
normal maintenance requirements
ongoing losses

22. Fluid and Electrolyte Therapy
Normal maintenance requirements
use BW formula
On going losses
measure all losses in I/O chart
estimate third space losses
Deficits
estimate using vital signs
estimate using U/O

23. Fluid and Electrolyte Therapy
The best estimate of the volume required
is the patients response
After therapy started observe
vital signs
Urine output (0.5mls/Kg/hr)
Central venous pressure

24. Time Frame for Replacement
Usually correct over 24 hours
For ill patients calculate over shorter period and reassess e.g. 1, 2 hours or 3 hours for e op cases
Deficits - correct half the amount over the period and reassess

25. Postoperative Fluid Therapy
Check IV regimen ordered in op form
Assess for deficits by checking I/O chart and vital signs
Maintenance requirements calculated
Usually K not started
Monitor carefully vital signs and urine output

26. Postoperative Fluid Therapy
Urine specific gravity may be used ( )
CVP useful in difficult situations (5-15 cm H20)
Body weight measured in special situation e.g. burns

27. Concentration Changes
changes in plasma Na are indicative of abnormal TBW
losses in surgery are usually isotonic
hypoosmolar condition usually caused by replacement with free water