1. Perioperative Fluid Management

2. Introduction
The goal of fluid management is the maintenance or restoration of adequate organ perfusion and tissue oxygenation
The ultimate consequence of inadequate fluid management is hypovolemic shock

3. Body Water Distribution
Total Body Water (TBW) is around 60% of body weight
Fluid in the body is divided into:
Intracellular fluid (2/3 of TBW)
Extracellular fluid (1/3 of TBW)
2/3
1/3
TBW = 60% body wt

4. Body Water Distribution
Extracellular fluid (ECF) is divided into:
Intravascular fluid (1/4 of ECF)
Interstitial fluid (3/4 of ECF)
Transcellular fluid
Transcellular fluid is fluid in spaces such as the peritoneum and pleural spaces
3/4
1/4

5. Distribution of TBW in 70 Kg Male

6. Volume Replacement
Sodium (and water) distributes throughout extracellular fluid:
1/4 intravascular (IV)
3/4 interstitial (IS)
You have to give four times as much saline or Ringer’s to replace loss of intravascular volume IS IV

7. Volume Replacement
Colloids (protein and starches) remain intravascular as long as capillary membranes are intact
Colloidal pressure causes some fluid to shift from the interstitial to the intravascular space
Increases expansion of intravascular volume IS IV

8. Volume Management Blood is lost from the intravascular space
Blood pressure and tissue perfusion rely on adequate volume in the intravascular space
Lost blood must be replaced with volume in the intravascular space

9. Volume Management For 500mL blood loss
You have to replace with 4 x 500mL = 2000mL of saline or Ringer’s
Because 3/4 will diffuse into interstitial space
2000
500

10. Volume Management For 500mL blood loss
You have to replace with mL colloid (5% Albumin, 10% Pentaspan)
Fluid shift because of colloid oncotic pressure will replace remainder of blood loss
350
500
150

11. Distribution of IV fluid in body compartments

12. Daily water turnover

13. Perioperative Fluid Requirements
The following factors must be taken into account:
1- Maintenance fluid requirements
2- NPO and other deficits: NG suction, bowel prep
3- Third space losses
4- Replacement of blood loss
5- Special additional losses: diarrhea

14. 1- Maintenance Fluid Requirements
Insensible losses such as evaporation of water from respiratory tract, sweat, feces, urinary excretion. Occurs continually.
Adults: approximately 1.5 ml/kg/hr
“4-2-1 Rule”
- 4 ml/kg/hr for the first 10 kg of body weight
- 2 ml/kg/hr for the second 10 kg body weight
- 1 ml/kg/hr subsequent kg body weight
- Extra fluid for fever, tracheotomy, denuded surfaces

15. Example: a 60 Kg woman fasting for 8 hours

16. 2- NPO and other deficits
NPO deficit = number of hours NPO x maintenance fluid requirement.
Bowel prep may result in up to 1 L fluid loss.
Measurable fluid losses, e.g. NG suctioning, vomiting, ostomy output, biliary fistula and tube.

17. 3- Third Space Losses
Isotonic transfer of ECF from functional body fluid compartments to non-functional compartments.
Depends on location and duration of surgical procedure, amount of tissue trauma, ambient temperature, room ventilation.

18. Replacing Third Space Losses
Superficial surgical trauma: 1-2 ml/kg/hr
Minimal Surgical Trauma: up to 5 ml/kg/hr
- head and neck, hernia, knee surgery
Moderate Surgical Trauma: up to 10 ml/kg/hr
- hysterectomy, chest surgery
Severe surgical trauma: up to 15 ml/kg/hr (or more)
- AAA repair, nehprectomy

19. 4- Blood Loss
Replace 3 cc of crystalloid solution per cc of blood loss (crystalloid solutions leave the intravascular space)
When using blood products or colloids replace blood loss volume per volume

20. 5- Other additional losses
Ongoing fluid losses from other sites:
- gastric drainage
- ostomy output
- diarrhea
Replace volume per volume with crystalloid solutions

21. Commonly used intravenous fluids:
Crystalloids
Colloids
Blood/blood products and blood substitutes

22. Crystalloids
Combination of water and electrolytes
- Balanced salt solution: electrolyte composition and osmolality similar to plasma; example: lactated Ringer’s

23. Colloids
Fluids containing molecules sufficiently large enough to prevent transfer across capillary membranes.
Solutions stay in the space into which they are infused.
Examples: hetastarch (Hespan), albumin, dextran.

24. Composition

25. Clinical Evaluation of Fluid Replacement
1. Urine Output: at least 1.0 ml/kg/hr
2. Vital Signs: BP and HR normal
3. Physical Assessment: Skin and mucous membranes no dry; no thirst in an awake patient
4. Invasive monitoring; CVP or PCWP may be used as a guide
5. Laboratory tests: periodic monitoring of hemoglobin and hematocrit

26. Summary
Fluid therapy is critically important during the perioperative period.
The most important goal is to maintain hemodynamic stability and protect vital organs from hypoperfusion (heart, liver, brain, kidneys).
All sources of fluid losses must be accounted for.
Good fluid management goes a long way toward preventing problems.

27. Thank You