1. INTRAVENOUS FLUIDS & ORAL REHYDRATION SOLUTION
Dr Ruwan Parakramawansha
MBBS, MD, MRCP(UK),MRCPE, DMT(UK)
(2013/01/30)

2. LEARNING OUTCOMES.. By the end of this lecture you will be able to,
List different types of IV fluids
Identify different methods of classifying i.v. fluids
Understand differences in fluids in relation to their distribution in different fluid compartments of the body
Describe indications for IV therapy
Outline complications of IV therapy
List constituents of ORS

3. FLUID DISTRIBUTION IN THE BODY
Total body water (TBW)
In males – 60% of body weight
In females – 55% of body weight
e.g. In a 60kg male – TBW is 36L

4. TBW = 60% OF BODY WEIGHT ICF ECF 05% 40% 15% Plasma Interstitial Fluid
Our intravascular compartment holds the smallest amount of water at around 3 litres ( a further 2 litres of red cells makes up our total blood volume ).
15%
Interstitial Fluid

5. TYPES OF I.V. FLUIDS Crystalloids vs. Colloids CRYSTALLOIDS COLLOIDS
Normal (0.9%) saline
Human Albumin
Ringer's lactate solution (Hartmann's' solution)
Gelatin solutions (Haemaccel,Gelafundin )
5% Dextrose
Dextran
Hydroxyethyl starches
(Hetastarch)

6. TYPES OF I.V. FLUIDS Hypotonic, Isotonic and Hypertonic solutions
HYPOTONIC SOLUTIONS
ISOTONIC SOLUTIONS
HYPERTONIC SOLUTIONS
0.45% (N/2) Saline
Normal (0.9%) saline
3% Saline
0.18% (N/5) Saline
Hartmann's' solution
Mannitol
5% Albumin
20% Albumin
Tonicity – osmolality of a solution relative to the osmolality of plasma

7. TYPES OF I.V. FLUIDS Balanced vs. unbalanced intravenous fluids
UNBALANCED SOLUTIONS
BALANCED SOLUTIONS
0.9% Saline
Hartmann's' solution
Dextrans
have a number of additional components to normal saline in an attempt to approximate the composition of the solution to plasma.
Balanced colloids are being developed.

8. TYPES OF I.V. FLUIDS Natural vs. Synthetic NATURAL SOLUTIONS
SYNTHETIC SOLUTIONS
Human Albumin
Gelatin solutions (Haemaccel,Gelafundin )
Fresh Frozen Plasma
Hartmann’s solution
Dextran

9. CRYSTALLOIDS
Consist of inorganic ions and small organic molecules dissolved in water
Either glucose or sodium chloride (saline) based.
May be isotonic, hypotonic or hypertonic
Both water and the electrolytes in the crystalloid solution can freely cross the semi permeable membranes of the vessel walls into the interstitial space

10. Normal Saline (0.9% NaCl)
Contains sodium and chloride ions in water and it is isotonic with extracellular fluid
Cell membrane is impermeable to Na+ and Cl- ions owing to the presence of the energy dependant
Na+ /K+ - ATPase
Intravenous infusion of an isotonic solution of sodium chloride will expand only the extracellular compartment

11. Normal Saline (0.9% NaCl)
Na+ is the main solute in ECF saline is well suited to replace ECF fluid losses
e.g. dehydration due to nausea/vomiting
Na+ and Cl- freely moves across vascular membrane into the interstitium.

12. Normal Saline (0.9% NaCl)
Remain in the intravascular space for only a short period before diffusing across the capillary wall into the interstitial space.
1 liter infusion of normal (0.9%) saline will result in
~ 250 ml expansion of the circulating volume.
Achieve equilibrium in 2-3 hours.

13. Normal Saline (0.9% NaCl) Indications:
Replacement of fluids in hypovolaemic or dehydrated patients ( Needs 3  blood loss)
A small amount of saline as a special adjunct can be used to keep the veins open for medication administration
As the initial plasma expander in blood loss while blood is typed and matched
In dengue patients as once hypovolaemia sets in there is circulatory collapse, Some points may apply for other crystalloids

14. Normal Saline (0.9% NaCl) Adverse Effects
Fluid overload (peripheral and pulmonary oedema)
With high volume administration,
Dilutional reduction of normal plasma components such as calcium and potassium
Dilutional coagulopathy
Hyperchloraemic acidosis
Diuresis.
Story about dengue deaths and alkaline diuresis used in Aspirin poisoning earlier, now abondoned due to risk of pul oedema

15. 5% Dextrose Initially behave as an isotonic solution.
Glucose is soon metabolized, leaving behind water making the solution hypotonic.
Water freely moves between intravascular, interstitial and intracellular fluid compartments till the osmolalities become the same.

16. 5% Dextrose Indications:
To maintain water balance ( In pure water deficit and for patients on sodium restriction)
To supply calories ( ~ 200kcal/l)
An adult require ~2500 kcal/day
Hence, glucose alone can’t meet the need.
Would need >10 liters of 5% glucose to supply all calories !!
Not used for fluid resuscitation. Wernicke’s encephalopathy. The brain is surrounded by a membrane separating it from the vascular space - the blood-brain barrier. This membrane will only allow water to pass through it. Therefore only fluid with the same concentration of sodium as plasma should be given intravenously. Otherwise, the plasma will become more dilute and water will pass from it into the brain, making the brain swell, and thus increase pressure further.
Normal Saline (0.9%) has a similar concentration of sodium and therefore is the fluid of choice for the brain. Colloid can be given if required to treat hypovolaemia due by major blood loss.
When Dextrose solutions in water (5% Dextrose, Dextrose 4%-Saline 0.18%) are given, the dextrose is metabolised leaving just the water or a very dilute saline solution. This "dilutes" the blood, reducing the concentration of sodium in the plasma. The water then passes into the brain where the concentration of sodium is higher. The brain then swells, and intracranial pressure will rise.

17. 5% Dextrose Adverse effects:
Causes red cell clumping (cannot be given with blood).
May cause water intoxication
Can cause hyponatraemia

18. Ringer’s Lactate A balanced isotonic electrolyte solution.
Similar to 0.9% saline in all aspects except,
Contains sodium, chloride, potassium, calcium and lactate in water. ( “physiological”)
Prevents dilutional reduction of normal plasma components such as calcium and potassium
Avoids hyperchloraemic acidosis ( Lactate converted to bicarbonate in liver.)
 Preferred to normal saline when large quantities of volume infused rapidly

19. COLLOIDS
Colloids contain large molecules such as proteins that do not readily pass through the capillary membrane
Remain in the intravascular space for extended periods
These large molecules also increase the osmotic pressure in the intravascular space 
Cause fluid to move from the interstitial and intracellular space to the intravascular space
 Often referred to as volume expanders

20. COLLOIDS
Colloids stay in the vascular compartment for a longer time compared to crystalloids
Administered in a volume equal to the volume of blood lost.
COLLOIDS
NORMAL SALINE
HALF LIFE IN INTRAVASCULAR COMPARTMENT
3-6 hrs
20-30 min

21. INDICATIONS When rapid expansion of plasma volume is desirable
e.g. in haemorrhage prior to blood transfusion
For fluid resuscitation in the presence of hypoalbuminaemia
In large protein losses e.g. in burns
Usually both colloids and crystalloids used to expand both vascular and interstitial compartments in resuscitation.

22. Gelatins Prepared by hydrolysis of bovine collagen.
a). Gelafusine  - succinylated gelatin in isotonic saline
b). Haemaccel - urea-linked gelatin and polygeline
in an isotonic solution of sodium chloride with
potassium and calcium.
Theoretical risk of transmitting bovine spongiform encephalopathy. (new-variant Creutzfeldt-Jakob disease)
Volume expanding effect lasts 2-3 hrs.
Because of the significant calcium content of Haemaccel, blood should not be
infused through a giving set that has been previously used for this product.

23. Dextrans
High molecular weight D-glucose polymers prepared from the juice of sugar beets.
Preparations of different molecular weights
e.g. Dextran 40 (MW 40,000)
Dextran 70 (MW 70,000)
Volume expanding effect lasts 5-6 hrs.

24. Dextrans Causes haemostatic derangements
Factor VIII activity is reduced
plasminogen activation and fibrinolysis is increased
platelet function impaired
Interfere with blood cross matching
Alter laboratory tests
e.g. Plasma glucose, plasma proteins
In patients whose haemostatic function is normal prior to infusion a maximum dose of 1.5 g/kg is often
recommended to avoid risk of bleeding complications.

25. Hydroxyethyl starches
Synthesized from amylopectin(a D-glucose polymer with a branching structure) derived from maize or sorghum.
The larger molecular size leads to prolonged intravascular retention compared to other colloids.
e.g. Hetastarch, Pentastarch
Even more than albumin

26. Human Albumin
Two preparations 5% albumin (isotonic) and 25% albumin (Hypertonic)
20% albumin expands the plasma volume up to five times the volume infused.
Heat treated -  no risk of transmitting viral infections.
Reduce ionized calcium level.
Even more than albumin

27. PHYSIOLOGY
Water is transported paracellularly as a result of the osmotic gradient.
- Water is absorbed along the osmotic gradient created by shift of electrolytes mainly Na+ and Cl-
- One form of sodium absorption occurs coupled to glucose.

28. In Diarrhoea……..
Imbalance between absorption and secretion of fluid and electrolytes.
Prompt fluid replacement can prevent dehydration and mortality( esp. in children)
Na+ - K+ ATPase
Na+ - Glucose co-transport unaffected
It is estimated that in the 1990s, more than 1 million deaths related to diarrhoea may have been prevented each year, largely attributable to the promotion and use of ORT and ORS.
unaffected

29. THE “NEW” WHO/UNICEF ORS FORMULA
A reduced osmolarity formula.
Contains reduced amounts of glucose and sodium.
Further reduces….
- stool out put
- vomiting
- unscheduled supplemental intravenous therapy
Associated with increased risk of hyponatraemia

30. WHO/UNICEF LOW OSMOLARITY ORS FORMULA
Anhydrous Glucose
13.5 g/l
Sodium chloride
2.6 g/l
Potassium chloride
1.5 g/l
Sodium citrate
2.9 g/l
Cereal bases ORS better than glucose based ORS. Why?
Continuous slow releasing source of glucose
Colonic bacteria produce short chain fatty acids which further enhance colonic sodium and water absorption.