Transcript Slide 1

INTRAVENOUS FLUIDS
&
ORAL REHYDRATION SOLUTION
Dr Ruwan Parakramawansha
MBBS, MD, MRCP(UK),MRCPE, DMT(UK)
(2013/01/30)
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
FLUID DISTRIBUTION IN THE
BODY

Total body water (TBW)
 In
males
 In females
–
–
60% of body weight
55% of body weight
e.g. In a 60kg male – TBW is 36L
TBW = 60% OF BODY WEIGHT
ICF
ECF
05%
Plasma
40%
15%
Interstitial
Fluid
TYPES OF I.V. FLUIDS
1.
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)
TYPES OF I.V. FLUIDS
2.
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
TYPES OF I.V. FLUIDS
3.
Balanced vs. unbalanced intravenous fluids
UNBALANCED SOLUTIONS
0.9% Saline
Dextrans
BALANCED SOLUTIONS
Hartmann's' solution
TYPES OF I.V. FLUIDS
4.
Natural vs. Synthetic
NATURAL SOLUTIONS
SYNTHETIC SOLUTIONS
Human Albumin
Gelatin solutions
(Haemaccel,Gelafundin )
Fresh Frozen Plasma
Hartmann’s solution
Dextran
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
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
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.
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.
Normal Saline (0.9% NaCl)
Indications:
1.
2.
3.
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
Normal Saline (0.9% NaCl)
Adverse Effects
1.
Fluid overload (peripheral and pulmonary
oedema)
2.
With high volume administration,
3.
•
Dilutional reduction of normal plasma components such
as calcium and potassium
•
Dilutional coagulopathy
•
Hyperchloraemic acidosis
Diuresis.
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.
5% Dextrose
Indications:
1.
To maintain water balance ( In pure water deficit and
for patients on sodium restriction)
2.
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 !!
5% Dextrose
Adverse effects:
1.
Causes red cell clumping (cannot be given with
blood).
2.
May cause water intoxication
3.
Can cause hyponatraemia
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
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
COLLOIDS
–
Colloids stay in the vascular compartment for a longer
time compared to crystalloids
HALF LIFE IN INTRAVASCULAR
COMPARTMENT
–
COLLOIDS
NORMAL SALINE
3-6 hrs
20-30 min
Administered in a volume equal to the volume of blood
lost.
INDICATIONS
1.
When rapid expansion of plasma volume is
desirable
e.g. in haemorrhage prior to blood
transfusion
2.
For fluid resuscitation in the presence of
hypoalbuminaemia
3.
In large protein losses e.g. in burns
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.
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.
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
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
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.
PHYSIOLOGY
- Water is absorbed along the osmotic gradient created by
shift of electrolytes mainly Na+ and Cl-
27- One form of sodium absorption occurs coupled to glucose.
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
unaffected
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

29
Associated with increased risk of hyponatraemia
WHO/UNICEF
LOW OSMOLARITY ORS FORMULA
30
Anhydrous
Glucose
13.5 g/l
Sodium chloride
2.6 g/l
Potassium
chloride
1.5 g/l
Sodium citrate
2.9 g/l