| LARGE ANIMAL EMERGENCY SERVICE |
LARGE ANIMAL 5-SECOND CONSULT |
Oral fluids may be useful in treatment of a large colon impaction however they should not be used in horses with suspected proximal gastro-intestinal disorders. DO NOT GIVE ANYTHING PER NASOGASTRIC TUBE OR PER OS IF REFLUX IS PRESENT!
Intravenous fluids should be a balanced electrolyte solution with a similar composition to plasma. (a balanced polyionic fluid +/- supplementation of potassium or calcium). Hypertonic fluids may be administered to horses in hypovolemic shock.
In the trauma patient, fluid resuscitation should be closely monitored and may need to be modified frequently. In choosing a fluid, consider the animal's physical condition and hydration and keep in mind whether the goals are resuscitation and/or perfusion.*
Fluid deficit in the intravascular -- primarily a perfusion problem*
Fluid deficit in the interstitial or intracellular space (extravascular) -- primarily a hydration problem*
FLUID SELECTION
Colloids* --
small molecules permeable to capillary membranes
also have high molecular weight molecules --- do not readily leave the intravascular space
osmotic effect increases intravascular volume, prolong resuscitative effect of hypertonic saline
decrease volume of isotonic crystalloids used
administer slowly; may have complications
expensive
examples: whole blood, concentrated albumin, plasma and plasma products, dextrans, hetastarch, synthetically derived colloids (see below)
Crystalloids* --
water-based solution with small molecules which are permeable to capillary membranes
mainstay of maintenance fluid therapy
used during hemorrhagic shock for interstitial volume replacement
decreased plasma proteins lead to a decrease in COP
isotonic crystalloids: used during traumatic situations for resuscitation
examples of isotonic crystalloids: lactated Ringer's(see below), Plasmalyte-ATM, or Normosol-RTM
hypertonic crystalloids: used during traumatic situations for rapid intravascular volume expansion note: this increase is transient and therefore colloids are often included in the treatment to retain more of the water and sodium within the intravascular space
AVOID hypertonic fluids if there is ongoing loss of plasma, or existing interstitial dehydration
examples of hypertonic crystalloids: 3.0%, 7.0% and 7.5% saline and 5% glucose added to balanced electrolyte solutions or maintenance solutions (see below)
Plasma --
used more often than other colloids
used to fight endotoxemia
optimally need to keep protein levels above 4.0 g/dl
difficult to replace protein deficits; may have complications
Oxyglobin --
synthetic hemoglobin base with oxygen carrying capacity
acute resuscitation of patients with hypotension due to hemorrhage, hemolytic anemia, neoplasia, parasitic blood loss, or sepsis with anemia
increases plasma and total hemoglobin concentration
increases arterial oxygen content
do not require x-matching
carry little risk of infection
can be frozen up to a year
Dextrans* --
hyperoncotic compared to normal plasma
antithrombotic effects due to hemodilution of blood leads to destabilization of clot formation
bilirubin values can be falsely increased
Dextran 40 has been associated with acute renal failure, anaphylaxis, and bleeding diathesis in small animals (not seen in Dextran 70)
Hetastarch* --
restrict infusions to moderate dosages to avoid thrombocytopenia, platelet coating , decreased serum concentration of coagulation proteins and increased thromboplastin times
.9% NaCl (normal saline) --
freely permeable to vascular membrane
distributes to plasma and ISF volume
should not have shift between ICF & ECF
requires large volumes if used for resuscitation of shock
Lactated Ringer's --
similar effect as saline for expansion of plasma volume
freely permeable to vascular membrane
poorly retained in vascular space
uses lactate as a buffer -- requires functioning liver
contains calcium -- blood products cannot be administered concurrently (i.e. in the same line -- will cause clotting in the line)
Normosol/Plasmalyte --
identical
uses acetate and gluconate as buffers (instead of lactate) and therefore, can be used in an animal with liver disease
contain magnesium -- may be beneficial to critical patient
Hypertonic Saline --
expands the plasma volume rapidly and improves tissue perfusion
favors retention of intravascular fluid and prevents washout of interstitial proteins
stimulates cardiac contractility
short term measure -- use low volumes & follow up with isotonic fluids
avoid if renal failure, arrhythmias, coagulopathies
4 ml/kg over 15 minutes
5% Dextrose in water (D5W) --
does not contain electrolytes
distributed throughout TBW space
only small change in plasma volume therefore it is not recommended for fluid resuscitation
* Taken from Kirby, R. and Rudloff, E. -- Fluid Therapy for the Trauma Patient. In: Emergency Care of Trauma Patients, The 22nd Annual Waltham/OSU Symposium For the Treatment of Small Animal Diseases. October 10-11, 1998.
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