Fluid Therapy

Question 1

what are the 3 components of a fluid plan

Answer 1

1. volume
2. route and rate
3. fluid type

Question 2

isotonic crystalloids

Answer 2

osmolality is similar/equal to the patient’s plasma

• LRS
• plasmalyte
• 0.9% NaCl
• D5W

Question 3

how should K+ supplementation be used

Answer 3

when fluids are running at 1-3x maintenance rate ONLY

should never be used in a rapid rehydration plan (over 4-6 hours)
- want to add at a slow rate

Question 4

dehydration

Answer 4

loss of both water AND salt - not pure water loss

Question 5

how is dehydration evaluated

Answer 5

history, PE, lab data

Question 6

PE parameters for dehydration

Answer 6

1. skin turgor
2. MM moisture
3. eye position
4. body weight

Question 7

skin turgor

Answer 7

skin elasticity

decreases with dehydration
- normal: returns immediately
- 5% deficit: slow to return
- 12% deficit: remains standing

affected by BCS and age

Question 8

evaluating MM moisture

Answer 8

gums: tacky
tear film: decreased

Question 9

evaluating eye position

Answer 9

sunken eyes

late stage dehydration - indicates moderate to severe dehydration

Question 10

lab data indicating dehydration

Answer 10

• USG > 1.030
• urine output < 1 mL/kg/hr
• PCV/TP: elevated
  +/- hypernatremia

Question 11

what are the categories of dehydration

Answer 11

mild: 5-7%
moderate: 8-10%
severe: 10-12%

Question 12

equation for calculating fluid deficit

Answer 12

L of deficit = % dehydration x kg BW

Question 13

route for replacing fluid deficit

Answer 13

SQ or IV

Question 14

how to calculate rehydration rate for fluid deficit

Answer 14

volume deficit / 4 to 6 hours

larger deficits require faster rehydration

slower rates for cardiac disease or geriatric cats

Question 15

maintenance rate

Answer 15

accounts for urine production and insensible (respiratory) losses

Question 16

what is the standard maintenance rate for all mammals

Answer 16

2-4 mL/kg/hr

Question 17

how should maintenance rate change for neonates

Answer 17

increase to 4-6 mL/kg/hr

Question 18

dog allometric rate for maintenance

Answer 18

80 x BW^3/4

Question 19

cat allometric rate for maintenance

Answer 19

70 x BW^3/4

Question 20

what is the average daily loss of potassium

Answer 20

15-20 meq/L

does NOT get sufficiently replaced in isotonic crystalloids

Question 21

what is the maximum safe rate of K+ supplementation

Answer 21

0.5 meq/kg/hr

Question 22

what are considered abnormal losses

Answer 22

vomiting, diarrhea, polyuria, cavitary effusions

vomiting: small volume losses
diarrhea: large volume losses

Question 23

average K+ loss from GI losses

Answer 23

10-30 meq/L

Question 24

range of estimating abnormal losses

Answer 24

1/2 to 2x maintenance rate

estimation based on severity and duration of abnormal losses

Question 25

how to estimate abnormal ongoing losses in severe dehydration

Answer 25

fluid deficit / hours of loss

Question 26

colloids

Answer 26

high molecular weight substance that largely remains in the intravascular compartment and generates an oncotic pressure

Question 27

what molecule contributes to oncotic pressure

Answer 27

albumin

Question 28

do crystalloids have oncotic pressure

Answer 28

NO - only colloids

Question 29

what are natural colloids

Answer 29

albumin
plasma

Question 30

what are synthetic colloids

Answer 30

hetastarch
vetstarch

Question 31

rate of hetastarch supplementation

Answer 31

1 ml/kg/hr added to total fluid need

remove the same amount of crystalloid

Question 32

indications for colloid therapy

Answer 32

1. albumin < 1.5 g/dL
2. interstitial edema due to LOW COP and patient requires fluid therapy

Question 33

how does anesthesia affect patient’s fluid needs

Answer 33

1. patient is fasted –> decreased/no fluid intake
2. drug side effects –> fluid shifts and hypotension
3. breathing dry, cold air –> evaporative fluid loss
4. exposed tissue –> evaporative fluid loss
5. hemorrhage –> volume loss
6. stress response to anesthesia/sx
7. degradation of glycocalyx

Question 34

what are reasons for fluid administration under general anesthesia

Answer 34

1. requires placement of IVC
2. replaces insensible losses due to extravasation
3. meets maintenance requirements
4. compensates for losses during procedure
5. replaces absolute and relative deficits

Question 35

goal of fluid administration under general anesthesia

Answer 35

maintain tissue perfusion and O2 pressure

Question 36

when should anesthesia be avoided in fluid compromised patients

Answer 36

• major fluid deficits
• hypovolemic
• dehydration

Question 37

do isotonic crystalloids effectively treat anesthesia induced hypotension

Answer 37

NO - poor volume expanders and distributes into tissues (does not remain in blood stream)

Question 38

what is a sample individualized fluid plan for surgery

Answer 38

1. basal requirement: 1 ml/kg/hr
2. insensible losses:
   - minimal sx: 1-2 ml/kg/hr
   - major sx: 3-6 ml/kg/hr
3. fasting deficit: 1-4 ml/kg/hr in the first hour only

total: 3-10 ml/kg/hr

typically within 3-5 ml/kg/hr

Question 39

what cardiac parameters does fluid therapy influence

Answer 39

preload

Question 40

what is the goal of fluid therapy (volume expansion)

Answer 40

optimize/increase stroke volume and cardiac output

Question 41

do all patients increase stroke volume in response to fluids

Answer 41

NO - only patients on the lower end of the Frank Starling curve will have an increase in stroke volume in response to fluids

Question 42

how to monitor if a patient will benefit from fluids

Answer 42

arterial BP tracing

if systolic pressure DECREASES during inspiration, the patient will benefit from fluid therapy