–   
Small volumes produce immediate
increases in blood pressure

bigger = longer

•     
Duration of effect is determined by
molecular size:

•     
Stays within the vasculatureà maintain
blood pressure

•     
Used when quantity of a crystalloid is
too great to be able to infuse quickly

•     
Dextrans, Hetastarch

Synthetic Colloids

 

–   
Packed RBC’s

–   
Platelet-rich plasma

–   
Plasma

–   
Whole blood

•     
Blood products:

          Natural Colloids

Colloids are
large-molecular-weight substances that are restricted to the plasma compartment
in patients with an uncompromised intact endothelium

Colloids

•     
Used for hypoglycemia, neonates,
hyperkalemia, as part of Total Parenteral Nutrition

•     
25%, 50% dextrose commonly found

•     
5% dextrose is isotonic

Dextrose
Solutions

•     
Used as a carrier for some drugs

•     
Used for hyperkalemia, hypercalcemia

•     
Lacking in K+, Ca2+

•     
0.9% Sodium chloride = ISOTONIC

Saline

–   
Because
small animals that are sick or under anesthesia tend towards acidosis

–   
Also contains lactate, which is
metabolized by the liverà
alkaline-forming

–   
Contains physiological concentrations
of: sodium, chloride, potassium, and calcium

•     
Composition closely resembles ECF

Lactated Ringer’s
Solution

–   
Osmolality higher than plasma, RL

•     
Hypertonic

–   
Mimic plasma electrolyte
concentrations, NS

•     
Isotonic

Crystalloid
Fluids

–   
Plasmalyte, Normosol, etc

–   
5% Dextrose in water

–   
Ringers Solution

–   
Lactated Ringers Solution

–   
0.9% NaCl

•     
Crystalloids

Types of Fluids:

 

–   
Used frequently in birds

– 
Femur or Humerus are commonly used

•     
Into the medullary (bone marrow)
cavity of long bones

•     
If situation is dire and no vein
accessible

 

•     
Intraosseous

•     
Catheter reactions (swelling, fever)

•     
Volume overload

–   
Possible problems:

–   
Best route in dehydrated animals

•     
Intravenous

–   
Can’t add glucose, large quantity KCl,
or some drugs

–   
Sometimes need to use multiple sites

–   
Works well in most animal  

•     
Subcutaneous

–   
Safest route if tolerated

–   
If the stomach works, use it!

•     
Oral

Administration
Routes

 

–   
Increased BP

–   
Decreased PCV, TP

–   
Restlessness

–   
Dyspnea, crackles

–   
Serous nasal discharge

•     
Overdose:

•     
Central venous pressure

•     
Urine production – 1-2ml/kg/min

–   
Serous nasal discharge

–   
Wheezes

–   
Crackles

•     
Auscult the lungs – presence of the
following signs indicate overhydration

•     
Weigh patient daily

Monitoring While on Fluids:

 

•     
It usually is not necessary to replace
the hydration deficit rapidly in chronic diseases, it should be done over a
period of 24 hours

•     
Severe ongoing losses (e.g., vomiting
and diarrhea in a patient with acute gastroenteritis) may necessitate rapid
administration to keep pace with contemporary fluid loss

•     
Reminder of the deficit + maintenance
req. + ongoing losses should be administered over a period of 24 hrs

•     
1/4th to ½ of fluid defecit
should be administerd over a period of 2-3 hrs

 

                                             colloids 20ml/kg/hr

•     
In case of shock – crystolloids 80-90
ml/kg/hr

•     
In Normal cases (peri-operative) it is
10ml/kg/hr

•     
Rate of fluid to be administered is
determined by the magnitude and rapidity of fluid loss

Rate of Administration:

 

It includes
losses related to vomiting, diarrhea, polyuria, large wounds or burns, drains,
peritoneal or pleural losses, panting, fever, and blood loss

On-going Losses: These are losses
that are occurring during the course of treatment

 

·       Usually
40-60 ml/kg/day

Maintenance requirement: The maintenance
fluid requirement is the volume needed per day to keep the animal in balance
(i.e., no net change in body water).

•     
Fluid req
(L) = Weight (Kg) X %dehydration

Fluid deficit: It is the deficit of plasma volume
calculated by multiplying weight in Kgs by percent dehydration which gives the
fluid deficit in litres

 

3.   
On-going
losses

2.   
Maintenance
requirement

1.   
Fluid deficit

  Fluid therapy contains
three components that should be taken into consideration.

Components of Fluid Therapy:

 

 

 

•      Skin tenting test – >3 sec indicate
dehydration

•      BUN, creatinine  – increased =”Prerenal azotemia”

•      albumin or total protein increased

–    PCV (HCT) – increased

•      Weight loss

•      Physical exam

Diagnosing Dehydration:

 

 

(
Muir WW, DiBartola SP: Fluid therapy. In Kirk RW, editor: Current veterinary
therapy VIII, Philadelphia, 1983, WB Saunders, p 33.)

·      
12-15      Definite signs of shock Death imminent

   Possibly signs of shock
(tachycardia, cool extremities, rapid and weak pulses)

   Dry mucous membranes

   Eyes sunken in orbits

   Definite prolongation of
capillary refill time

·      
10-12      Tented skin stands in place

               Possibly dry mucous membranes

               Eyes possibly sunken in orbits

               Slight prolongation of capillary
refill time 

·      
6-8          Definite delay in return of skin to
normal position

·      
5-6          Subtle loss of skin elasticity

·      
<5           Not detectable Percent Dehydration Signs of dehydration: •      Diuresis (renal disease, toxicities) •      Prevent dehydration (GI disease) •      Deliver drugs in a constant-rate infusion •      Correct electrolyte abnormalities •      Correct acid-base abnormalities d/t disease •       Correct dehydration Why Should we Give Fluids :   Fluid therapy is supportive. The underlying disease process that caused the fluid, electrolyte and acid base disturbances in the patient must be diagnosed and treated appropriately. Normal homeostatic mechanisms allow the clinician considerable margin for error in fluid therapy, provided that the heart and kidneys are normal (Stephen P. DiBartola and Shane Bateman; Fluid Electrolyte and Acid Base Disorders in Small Animal Practice)   FLUID THERAPY IN SMALL ANIMAL