Fluid Therapy

Question 1

Why do we give IV fluids during anesthesia/in general?

Answer 1

Encourage perfusion to major organs
Promote blood flow to capillary beds
Correct on-going losses 
Counteract hypotension/vasodilation
Correct electrolyte or acid-base imbalances
Means to administer intra-op drugs IV

Question 2

What 3 compartments are body fluids divided into?

Answer 2

Intracellular fluid compartment (ICF)

Extracellular fluid compartment (ECF): intravascular and interstitial fluid compartments

Question 3

What are the 4 types of pressures involved in Starling’s force?

Answer 3

1. Capillary hydrostatic P
2. Capillary oncotic P
3. Interstitial hydrostatic P
4. Interstitial oncotic P
   * interstitial forces MUCH weaker

Question 4

What are the guidelines of a pre-operative assessment for IV fluid tx?

Answer 4

1. Clinical sx of dehydration and hypovolemia - skin tenting, dry mm, prolonged CRT, incr HR, cool extremeties, poor pulses
2. PCV/TS, lactate, BUN & Creat, USG
3. Co-morbidities affecting fluid admin - cardiac, renal, GI, and liver dz

Question 5

What is the difference between dehydration and hypovolemia? What are the clinical signs for both of them?

Answer 5

Dehydration = loss of whole body water
Clin Sx: loss of skin turn or, dry MM, sunken eyes, severe: weak pulses, tachycardia, hypotension, obtunded

Hypovolemia = loss of fluids from the vascular compartment
Clin Sx: tachycardia, hypotension, weak pulses, prolonged CRT, cool extremities

Question 6

What are the PE findings for a 5% dehydrated patient?

Answer 6

Minimal loss of skin turgor, dry MM, normal eye position

Question 7

What are the PE findings for a 8% dehydrated patient?

Answer 7

Moderate loss of skin turgor, dry MM, threads pulses, sunken eyes, incr HR

Question 8

What are the PE findings for a 10% dehydrated patient?

Answer 8

Considerable loss of skin turgor, severely sunken eyes, very dry mm, obtunded, incr HR, decr BP

Question 9

If I weigh a blood-soaked gauze sponge I used for surgery in a patient and it weighed 2 g, approximately how much blood was absorbed in that sponge?

Answer 9

2 mL

Question 10

Describe isotonic fluids. What are are few examples?

Answer 10

Electrolyte concentration very closely matches normal plasma levels

E.g. LRS, Plasmalyte 148, Normosol-R, 0.9% NaCl

Question 11

T or F: Hypotonic fluids are used often for patients under anesthesia

Answer 11

False - rarely used

Question 12

In what scenario would you use hypertonic fluids, such as hypertonic saline, for a patient?

Answer 12

If your patient needs very rapid volume expansion; used relatively often under anesthesia

Question 13

What are crystalloids used for, and what is a disadvantage to using them?

Answer 13

Treating dehydration and short term fluid replacement

Disadvantage: leave intravascular fluid compartment rapidly

Question 14

What are the uses of colloids, such as Hetastarch? Name some advantages and disadvantages

Answer 14

Uses: rapid volume expansion, oncotic support

Adv: dwell in IVF space

Disadv: volume overloading, coagulopathies, renal damage

Question 15

What is the effect of giving fresh frozen plasma vs. whole blood and packed RBCs?

Answer 15

Plasma: colloid, volume expansion, oncotic support, clotting factors

Whole Blood/Packed Cells: volume expansion, incr O2 carrying capacity

Question 16

What is the anesthetic maintenance fluid rate in dogs and horses vs. that in a cat?

Answer 16

5 mL/kg/hr (dogs, horses)

3 mL/kg/hr (cats) - less tolerant to fluid overloading

Question 17

What are the general guidelines for an isotonic fluid therapy plan?

Answer 17

1. Calculate fluid deficit, correct deficits prior to anesthesia by admin 1/4 dose and reassessing - admin remaining vol over 6-12 hrs
2. Add maintenance requirement
3. Add ongoing losses - estimate from sx hemorrhage, dieresis, GI losses and replace

Question 18

How do you calculate a patient’s fluid deficit?

Answer 18

Fluid deficit (L) = body weight (kg) x % dehydration

Question 19

What are the two main physiologic problems associated with hemorrhagic shock?

Answer 19

Hypovolemia and loss of O2 carrying capacity

Question 20

What is the idea behind low volume resuscitation for hemorrhagic shock?

Answer 20

Prevent dilution of RBCs and clotting factors, avoids large incr in BP, improves patient outcome

Question 21

What is a typical shock dose of isotonic crystalloids and how much should be administered in the case of hemorrhagic shock?

Answer 21

90/mL/kg; admin 1/4 to 1/3 of dose

Question 22

What is the typical fluid treatment plan for hemorrhagic shock?

Answer 22

1. ) 1/4-1/3 of shock dose of isotonic crystalloids
2. ) 2-4 ml/kg of hypertonic fluid SLOWLY over 5 min - repeat as needed
3. ) Admin 2-5 ml/kg bolus of colloid and repeat as needed UP TO total dose of 20 ml/kg/day

Question 23

What are two ways to estimate blood loss in the case of hemorrhagic shock?

Answer 23

Weighing sponges and the volume in the suction canister

Question 24

Each 2 mL/kg of whole blood will raise the PCV by what %?

Answer 24

1%

Question 25

How will fluid administration for a patient in hemorrhagic shock differ whether that patient is compensating well or not?

Answer 25

If patient is decompensating —> GIVE RAPIDLY!

If patient is compensating —> give over MAX 4 hours

Question 26

How do you calculate drip rates?

Answer 26

Body weight (kg) X maintenance rate (3 ml/kg/hr - cat; 5 ml/kg/hr - dog/horse) X whatever mL drip set you’re using

Approximate to 1 drop per however many seconds

Question 27

What is the idea behind goal-directed fluid therapy?

Answer 27

Using surrogate markers of perfusion and cardiac output to guide fluid therapy

E.g. HR, BP, CVP, lactate, pulse pressure variation, urine output

Question 28

Why do you need continuous IV access during an anesthetic procedure?

Answer 28

Provide fluid tx
Admin drugs
Transfusion tx
Anesthetic monitoring

= GOLD STANDARD of anesthetic care!

Question 29

What is a commonly used alternative in horses for IV catheterization if you do not have access to the jugular?

Answer 29

Lateral thoracic vein

Question 30

What site is the most commonly used for IVC in pigs?

Answer 30

The ear

Question 31

What makes placing a jugular catheter in camelids difficult?

Answer 31

Their jugular grooves are very difficult to see/feel —> typically approaching blind

Be careful of the carotid!

Question 32

Where would you place an IVC on a rabbit?

Answer 32

Marginal veins of the ears (be careful - their arteries are located in the center of the ear)

Question 33

What are two common places intraosseous catheterization is performed?

Answer 33

Intertrochanteric fossa and the tibial crest

Question 34

Why are intraosseous catheters in birds not placed in the humerus and femur?

Answer 34

Because they are pneumatic bones - use the ulna or tibiotarsus instead!

Question 35

What are the uses for arterial catheterization? Possible complications?

Answer 35

Monitoring of continuous BP
Monitoring of resp gases
Gold standard monitoring in horses
Challenging to perform in small animals

Complications: hemorrhage/hematoma, air embolism, inadvertent injection of drugs

Question 36

What are some possible complications of vascular access?

Answer 36

Vessel trauma 
Thrombophlebitis
Catheter site infection
Extravasation of fluids into SC tissues
Air embolization
Exsanguination
Thrombosis (esp arterial access)
Catheter breakage
Hematoma
Osteomyelitis (IO catheter)