1. PRINCIPLES OF FLUIDS AND ELECTROLYTES

2. Fluid Compartments Example: 70-kg male
Total Body Water: 42,000 mol(60% of BW)
Intracellular: 28,000 mL(40% of BW)
Extracellular: 14,000 mL(20% of BW)
Plasma: 3500 mL(5% of BW)
Interstitial: 10,500 mL(15% of BW)

3. DO2 = Cardiac Index x CaO2 x 10
= SV x HR x {(Hb x SaO2 x 1.34)
+ (0.003 x PaO2) }

4. Clinical Signs of Adequacy of Perfusion
Urine output
Mental status
Capillary refill
Skin color
Temperature
Pulse rate
Acid-base status
Lactate Levels
Oxygen consumption
Mixed Venous Oxygen Saturation

5. Perioperative Fluid Therapy
● Normal Daily fluid Requirements :
30-35 ml/kg/day for adult
+ 1 mmol/kg/day Na+
+ 1 mmol/kg/day K+

6. I Normal perioperative maintenance: - 1st 10 kg BW  4ml/kg/hr
- 2nd 10 kg BW  2ml/kg/hr
- each remaining kg  1ml/kg/hr
Types : D5 ¼ NS , DS ½ NS , LR
eg. 70kg man maintenance  =110ml/hr
II Pre-existing Deficits :
(a) Fasting : Maintenance /hr x Fasting hrs.
50% in 1st hr , 25% in 2nd hr , 25% in 3rd hr
(b) Preoperative deficits : vomiting- diarrheoa- ascites bleeding

7. III Replacement Requirement :
(1) Bood loss % Blood volume
- HB 7-10gm/dL
- Hct falls by>30%
Allowable Blood loss  volume of lost RBCs x 3
Each one unit of RBCs increase HB 1gm/dl & Hct 2-3%
(2) Evaporation and 3rd space loses :
-Minimal (eg. herniorhapy) 2ml/kg/hr
- Moderate (eg. cholecystomy) 2-4 ml/kg/hr
- Severe (eg. bowel resection) 4-8 ml/kg/hr
by lactate Ringer solution
(3) Abnormal fluid loss :
- GIT:nasogastic suction, sequestered fluid in gut
- urine
- Insensible loss (from skin or lung) = 0.5ml/kg/hr
increase 10 C increases insensible loss, about 12 %

8. Intravenous fluids Crystalloid solutions: Low molecular weight
Intravascular half life minutes
Hypotonic solutions: D5 W
For replacement of pure water deficits
As maintenance fluids for patient on Na restriction
Isotonic solutions (Replacement-type solutions)
For replacement of losses that involve water or electrolytes (eg intraoperative losses)
eg LR , NS
Hypertonic solutions:
Given via a central venous line
3% saline, 7.5% saline
used in hyponatremia , in hypovolemic shock

9. Isotonic Crystalloids :
●Normal Saline (0.9%)
(Na 154 meq/L, Cl 154 meq/L)
●Lactate Ringer’s (Hartman’s solution)
(Na 130 meq/L, Cl 109 meq/L, K 4 meq/L, Lactate 28 meq/L, Ca 3 meq/L)
● Ringer’s solutions
Na meq /L, Cl 156 meq/L, k 4 meq/L, Ca 2 meq/L
Hypotonic solutions
D5W (containing glucose 50gm/L)
Hypertonic solutions
D5 ¼ Ns ,(Na 77meq/L, Cl 77 meq/L, glucose 50gm/L)
D5 ½ NS , (Na 154 meq/L, Cl 154 meq/L, glucose 50 gm/L)
NHCo3 8.4%, (Na 1000 meq/L, HCO meq/L)

10. Colloid Solutions
. They are solutions containing high molecular weight substances, intravascular half-life 4-6 hrs
. Used in :
- hemorrhagic shock (severe intravascular deficits)
- severe hypoalbumenimia (or large protein loss eg. burns)
. Types:
1- blood derived human albumin 5,25%, plasma protein fraction 5%
2- synthetic colloid  a) starch eg. Dextran 70 or 40
b) Gelatines eg. Gelofusine, polygeline
3- Hestastarch eg. 6 % Hydroxyethyl starch