How do inhalants cause hypotension?
because they cause vasodilation and decrease myocardial contractility.
How does fluid therapy help treat hypotension caused by inhalants?
they maintain cardiac output by ensuring adequate preload
What is the equation for Mean Arterial Pressure?
MAP = CO x SVR
What is the equation for Cardiac Output?
CO = SV x HR
What is the generally recommended fluid rate for patients under general anesthesia?
What is the shock dose (AKA blood volume) for the horse?
What is the shock dose (AKA blood volume) for the dog?
What is the shock dose (AKA blood volume) for the cat?
What is the shock dose (AKA blood volume) for the sheep?
What is the shock dose (AKA blood volume) for the goat?
What is the shock dose (AKA blood volume) for the pig?
How do you administer fluid to treat hypotension in a patient?
Give bolus increments of the shock dose 5-10ml/kg at a time and reassess. Keep track of boluses.
How do you assess effectiveness of fluid therapy?
MAP (best option), CRT, pulse quality, heart rate, CVP, lactate, urine output
What are the pros/cons of MAP for monitoring effectiveness of fluid therapy?
MAP is often the best option for monitoring, but remember MAP = CO x SVR, so it's not just a measurement of perfusion. Increased SVR will also increase MAP without necessarily improving perfusion. We want that MAP > 60mmHg
What are the commonly used routes of fluid administartion and pros/cons of each?
IV - usually best option, allows for rapid resuscitation
SQ - not appropriate for emergency but convenient and inexpensive. MUST use isotonic fluid.
IO - allows rapid resuscutation in those with limited vascular access (birds and neonates)
IP - not appropriate for rapid resuscitation, useful in those with limited vascular access (reptiles), may lead to peritonitis
Name 3 options for isotonic replacement crytalloids.
1. LRS - contains lactate as a bicarb precursor, is useful in metabolic acidosis
2. Normosol R - contains gluconate and acetate as bicarb precursor, contains Mg but no Ca, useful in metabolic acidosis
3. Normal saline 0.9% NaCl - no buffer, useful for treating metabolic alkalosis
What is the pH and electrolyte difference between LRS and 0.9% NaCl?
LRS contains lactate as a bicarb precursor and is useful in treating metabolic acidosis whereas 0.9% NaCl has no buffer and is useful for treating metabolic alkalosis.
What are the hypotonic fluid options?
1. half-strength LRS and 2.5% dextrose
2. 0.45% saline and 2.5% dextrose
Note that dextrose solutions become hypotonic when dextrose is metabolized by cells, it's used in patients prone to hypoglycemia
What are the hypertonic fluid options?
hypertonic saline 7.5% NaCl - boosts IV volume, used for rapid, low-volume resuscitation of IV compartment at the expense of intracellular and interstitial spaces.
List the following in order of increasing vascular volume: hypertonic fluids, isotonic fluids, colloids.
colloids > hypertonic fluids > isotonic fluids
Name the 5 colloids.
hetastarch, dextrans, plasma, albumin, whole blood
Which fluid type would be most appropriate for hypoproteinemic patients?
What is the maintenance fluid rate?
60ml/kg/24 hours. Do NOT confuse this with the standard anesthetic fluid rate.
When would you adjust the standard anesthetic fluid rate in your patient?
If the patient is dehydrated, consider giving more, if patient is predisposed to fluid overload (congestive heart failure/pulmonary edema) consider giving less.
What is the maximum bolus amount for a patient in shock?
1 shock dose (blood volume) per hour
Our goal with fluid therapy is to maintain MAP at what level? What is the corresponding SAP?
MAP > 60
SAP > 80
What type of fluid can be used with SQ administration?
isotonic fluid only!
What are the 7 major complications with fluid therapy?
5. catheter embolism
7. fluid overload (pulmonary edema)
What is normal plasma osmolality?
To replace blood loss with crystalloid solution, how much do you give?
3-4 times the volume of blood lost
How much of the volume of crystalloid administered stays in the vascular space?
25% of it stays intravascularly.
Which fluid type is best for treating patients with cerebral or pulmonary edema?
What are the 3 main disadvantages in using colloids?
1. affect coagulation leading to prolonged bleeding time
2. patients can become hyperoncotic leading to oliguric acute renal failure
Which is preferred in critically ill patients: fresh whole blood or packed RBCs and why?
fresh whole blood preferred because packed RBCs are extremely acidotic.