Sakina Rubab
9th semester
DVM
Fluid Replacement Therapy

Fluid Therapy is the administration of fluids to a patient as a
treatment or preventative measure. It can be administered
via an intravenous, intraperitoneal,oral and other routes.

Indications
Hypovolemia
Hypotension
Electrolyte,
metabolic and
acid base
disorders
Decreased oxygen
delivery
Geriatric patients at
risk of organ failure

Special considerations
Shock
Anaesthesia
Hepatic diseases Central nervous
system diseases
Cardiac diseases

Mechanism of shock
 Changes in cardiac function
 Sympathetic N.S
 Compensatory changes

To assess whether a patient is in shock the
following signs may be seen:
 Tachycardia
 Pale mucous membranes (May be dark if
distributive shock)
 Prolonged/Absent capillary refill time
 Reduced/Absent peripheral pulses
 Hypotension

 Hypovolemic is seen when there is reduced
circulating blood volume and the most common
form of shock.
 Cardiogenic is seen in any condition when there
is a failure for the heart to pump effectively.
 Vascular can be sub-divided into -
 Obstructive is seen when there is an obstruction to
blood flow to a region of tissue.
 Distributive is seen when there is inappropriate
vasodilatation.

Dehydration status
 Semidry oral mucous membranes, normal skin turgor, and
eyes maintaining normal moisture indicate 4%–5%
dehydration.
 Dry oral mucous membranes, mild loss of skin turgor, and
eyes still moist indicate 6%–7% dehydration.
 Dry mucous membranes, considerable loss of skin turgor,
retracted eyes, acute weight loss, and weak rapid pulses
indicate 8%–10% dehydration.
 Very dry oral mucous membranes, complete loss of skin
turgor, severe retraction of the eyes, dull eyes, possible
alteration of consciousness, acute weight loss, slow and
weak pulses indicate ≥12% dehydration.

General indication
 Loss of fluid from compartment
 Severity(Dehydration status)
 Compartment
 Laboratory results
 Symptoms

Fluid Dynamics
 3 compartments: intravascular, interstitial and
intracellular (capillaries)
 A capillary “membrane,” which consists of the
endothelial cells and subendothelial cell matrix
(separation)
 This capillary “membrane” is freely permeable to
water and small-molecular-weight particles such
as electrolytes, glucose, acetate, lactate,
gluconate, and bicarbonate

 The interstitial compartment is the space between
the capillaries and the cells.
 The intracellular compartment is separated from
the interstitial space by a cell membrane.
 This membrane is freely permeable to water but
not to small- or large-molecular-weight particles.
 Interstitium and the cell :transport mechanism
(eg, channel, ion pump, carrier mechanism).

Types of fluids
Crystalloids are able
to enter all body
compartments.
Colloids are restricted
to the plasma
compartment.
electrolyte
imbalance

Crystalloids
 Ringer lactate
 Normal saline 0.45%,0.9%,7%
 Dextrose 2.5%,5%,10%,20%
 Hartmann’s solution
 Plasmalayte

Colloids
 Dextrans
 Hydroxyethyl starch (HES)
 Canine albumin
 Stroma free haemoglobin

Selection of fluids
Fluids must be administered that will concentrate
within the body fluid compartment where the
volume deficit lies.
Crystalloids are water-based solutions with small-
molecular-weight particles, freely permeable to
the capillary “membrane.”
Colloids are water-based solutions with a
molecular weight too large to freely pass across
the capillary “membrane.”

Colloids intravascular volume replacement
solutions
Crystalloids interstitial volume replacement
solutions.

Crystalloids
 The small-molecular-weight particles in
crystalloids are primarily electrolytes and buffers
.Intravascular administration of isotonic
crystalloids (e.g. lactated Ringer's, 0.9% saline)
will result in interstitial volume replacement and
minimal intracellular fluid accumulation.
 Hypotonic fluids (e.g.5% dextrose in water,
saline) will result in intracellular water
accumulation and should not be used as
resuscitation fluids.
 Hypertonic solutions (e.g. 7% NaCl) contain
higher concentrations of sodium and are best
used when hydration is normal and concurrently
with other fluids.

Colloids
 When colloids are to be administered, it must be
decided whether a natural colloid (e.g., plasma,
albumin, or whole blood) or a synthetic
colloid(HES,dextran) is to be used.
 When the animal requires RBCs, clotting factors,
antithrombin III, or albumin, blood products are
the colloids of choice.

When to use which solution?
 Hypotonic saline fluids such as 0.45% sodium
chloride solution
expand the intracellular compartment
hypertonic dehydration, gastric fluid loss, and
cellular dehydration from excessive diuresis.

 Isotonic saline fluids 0.9% sodium chloride
solution
 expand the extracellular compartment
 circulatory insufficiency, replenish sodium and
chloride losses, treat diabetic ketoacidosis,
replenish fluids in the early treatment of burns
and adrenal insufficiency.
 Because their osmolality is similar to that of
blood, they're also the standard flush solutions
used with blood transfusions.

 Hypertonic saline fluids 5% dextrose in 0.9%
sodium chloride solution
 are used cautiously to treat severe hyponatremia.

 Precautions: Closely monitor the patient for
complications, such as electrolyte imbalances,
calorie depletion, and increased intracranial
pressure (ICP).
 Because hypertonic fluids pull water from the
intracellular space into the extracellular space,
fluid volume and ICP can increase. Watch for fluid
overload in patients with a history of heart failure
or hypertension.

 Dextrose fluids, which contain dextrose and free
water(2.5%, 5%, 10%, 20%, and 50%)
 Dextrose fluids also are available in combination with
other solutions, such as sodium chloride or Ringer's
solution.
 Dextrose fluids provide calories for energy, sparing
body protein and preventing ketosis, which occurs
when the body burns fat.
 They also make it easier for potassium to move from
the extracellular to the intracellular compartment.
Dextrose fluids flush the kidneys with water, helping
them excrete solutes, and improve liver function
(glucose is stored in the liver as glycogen).

 Precautions: Never mix dextrose with blood ,it causes
blood to haemolyze. Prolonged therapy with dextrose in
water can cause hypokalemia, hyponatremia, and water
intoxication by diluting the body's normal level of
electrolytes.
 Severe hyponatremia can lead to encephalopathy, brain
damage, and death; young women are at highest risk.
(confusion, change in mental status)
 Hypertonic dextrose solutions can cause hyperglycemia,
leading to osmotic diuresis and hyperosmolar
coma.(serum glucose levels, urine specific gravity, and
fluid intake and output,polyuria, polydipsia, weight loss,
and weakness)
 Dextrose can be given to diabetic patients in acute illness
as long as the patient's blood glucose is closely monitored
so the balance of blood glucose and insulin is maintained.

 Electrolyte replacement fluids, Ringer's
solution:isotonic fluids containing electrolytes in
the same concentrations found in plasma.
 However, these solutions don't contain
magnesium and phosphorus, which shouldn't be
routinely given.
 The exact electrolyte content depends on the fluid
manufacturer. Ringer's injection and lactated
Ringer's solution, the two most common
electrolyte fluids, contain potassium, sodium,
chloride, and calcium. Lactate, added as a buffer
to produce bicarbonate, is contraindicated in
patients with liver disease because they can't
metabolize it.

 Electrolyte fluids provide hydration and
electrolytes for patients who can't take in food or
fluid orally and for those who've experienced
abnormally high fluid losses from severe vomiting,
diarrhoea or diuresis.
 Lactated Ringer's solution is also used for
volume replacement in patients with third-
spacing.
 5% dextrose may be mixed with the electrolyte
fluid to provide energy, keep in mind that the
resulting solution is hypertonic.

 Precautions:These fluids generally aren't given
for more than 48 hours (unless the patient's
condition is unchanged) because of the risk of
overhydration, hypernatremia, hyperkalemia,
metabolic alkalosis, and calorie depletion if the
fluid isn't mixed with dextrose.

Standard shock rate
 For crystalloid solution is 80 to 90 ml/kg for a dog
and 40 to 60 ml/kg for a cat, and it is normally
given in increments (e.g. one-third, one-half) of
the calculated amount over a period of 10 to 30
minutes.
 For colloid solution is 10 to 20 ml/kg for dogs and
5 to 10 ml/kg for cats.

Fluid rate calculation
Maintenance
Replacement
Ongoing Losses

Replacement
 Replacements are calculated based on the level
of dehydration. To calculate the amount required
for replacement within a 24 hour period, the
percentage dehydration is used in the following
calculation.
Replacement = % Dehydration x Bodyweight
(kg) x 10

Maintenance
 Maintenance is the basic rate which a patient
requires during a 24 hour period.
50ml/kg/24hr, or 2ml/kg/hr.

Ongoing Losses
 Ongoing losses are calculated based on a
predicted fluid amount lost by a patient within a
24 hour period.
 To calculate the fluid requirement, the following
calculation is used.
Ongoing losses = Amount per loss (ml/kg) xbody weight No. of
losses
Ongoing losses amount+ replacement
amount

Example
 Fluid replacement in a dog weighing 25kg.
 Replacement= %dehydration*body weight*10
=5% * 25kg* 10
=12.5ml
 Maintenance= 2ml/kg/hr
For 25kg: 50ml/hr or 1200ml/24hrs
 Ongoing losses= fluid lost ml/kg*body weight*no.of
losses
=100ml/25kg(vomition)*25kg*1
=100ml
 100ml+12.5ml+1200ml=1312.5ml/24hrs

 Requirement per hour (ml/hr) = Requirement
per day (ml/24hr) ÷ 24
 Requirement per minute (ml/min) =
Requirement per hour (ml/hr) ÷ 60
 Requirement per second (ml/s)= Requirement
per minute(ml/min) ÷ 60
 Drops per second = Requirement per second
(ml/s)x Giving Set Factor

Monitoring fluid therapy
urine output
Packed Cell
Volume (PVC)
Total Solids mucous
membrane color
Total Protein
blood pressure
oedema
Skin turgor

Clinical aspect
 Drips
 Syringes
 Rough estimation of dehydration status
 Quick administration

References
 http://www.merckmanuals.com/vet/emergency_m
edicine_and_critical_care/fluid_therapy/the_fluid_
resuscitation_plan.html
 http://www.theaec.com/content/111311ce/fluid_th
erapy.pdf
 http://en.wikivet.net/Principles_of_Fluid_Therapy
 http://veterinaryteam.dvm360.com/fluid-therapy-
calculating-rate-and-choosing-correct-solution

Thank you