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 hyperosmolarcoma.(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.oflosses

=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