Fluid Therapy

Question 1

Indications for fluid therapy

Answer 1

Decreased intake
dehydration
decreased circulating volume (shock)
need for overhydration
correct electrolyte abnormalities

Question 2

What clinical indicators are used to indicate need for fluid therapy

Answer 2

skin turgor (changes at 8-10%) - neck in adults, eyelid in foals or geriatric
MM - moisture level and CRT
urine production - decreased unless renal disease
sunken eyes - rare in horse
depression, muscle weakness
heart rate - tachycardia = one of first things you’ll see
decreased jugular distensibility

Question 3

What lab indicators are used to indicate need for fluid therapy?

Answer 3

PCV - splenocontraction can over or underestimate degree dehydration
TP - increase
BUN/Cr
Albumin - need to keep above 1.5g/dL, only cause of hyperalbuminemia is dehydration
lactate
urinalysis - typically USG of >1.030

Question 4

PCV increase iwith dehydration

Answer 4

for every 2-3% increase in % dehydration over 5%, PCV increases 5%

Question 5

5% dehydration

Answer 5

skin tent: 1-3s
MM - moist to slightly tacky
CRT - normal, <2s
HR - normal
Other: decreased urinary output

Question 6

8% dehydration

Answer 6

skin tent: 3-5s
MM - tacky
CRT - variable (2-3s)
HR - 40-60bpm
other: decreased arterial blood pressure

Question 7

10-12% dehydration

Answer 7

skin tent: 5 or more s
MM - dry
CRT - variable, often >4s
HR - >60bpm
other: reduced jugular fill, barely detectable peripheral pulse, sunken eyes

Question 8

15% dehydration

Answer 8

death imminent

Question 9

oral fluids

Answer 9

animals drink at own will
- never place electrolyte solution alone, always with access to free water

nasogastrically intubated - can leave in for short time to avoid repeated trauma, can give 6-8L = 12-16L/h (30m transit to stomach)
A: most physiologic, non-invasive, not expensive, can loosen impactions in LI
D: DON’T GIVE IF ILEUS, GASTRIC DISTENTION OR REFLUX

Question 10

IV fluids

Answer 10

place catheter so fluids flow towards the heart
typically 14G 5.5” Angiocath

A: easy access, allows easy change in fluid plan, almost unlimited available amount of fluids and rate
D: danger of compromise to vein, sepsis risk, sterility, cost, requires monitoring

Question 11

jugular vein

Answer 11

easy access, well tolerated, catheter inserted downwards

Question 12

Lateral thoracic vein

Answer 12

second choice, esp if dysfunction of one jugular v
catheter placed horizontal to gravity, towards head
poor choice for recumbent animal

Question 13

Cephalic vein

Answer 13

first choice for limb catheters, placed tip towards heart,
disadvantages: easily clots due to placement against gravity, advised to always have fluids running through, not used for medication administration alone

Question 14

Saphenous vein

Answer 14

easily bent due to limb motion, placement MUCH less tolerated, typically only used if “running out’ of veins

Question 15

Subcutaneous fluid administration

Answer 15

helpful in foal but rarely used, not used in skin

no clinical indications for use

Question 16

Intraperitoneal fluid administration

Answer 16

A: can get large volumes in at rapid rate, easy access, could be alternative if limited venous access
D: vigilant monitoring needed, sepsis is risk, except to get large volumes but practically cannot because fluid tracks down within abdomen

Question 17

Rectal fluid administration

Answer 17

use gravity flow or pump, have horse standing on an incline with head lower than hind limbs
A: no sterility required, absorption across gastric mucosa, potentially large fluid volumes, helpful if limited venous access
D: can’t help in moderate to severe ileus, cannot be used in severe colitis

Question 18

Intraosseus fluid administration

Answer 18

used in severe dehydration to increase circulatory volume if no jug filling, esp foals
D: difficult, strict sterility, limited rate of administration due to needle size

Question 19

Intracecal fluid administration

Answer 19

A: large volumes directly into intestinal segment with greatest absorption
D: more invasive, strict sepsis

Question 20

Rate of flow through system dependent on:

Answer 20

radius/diameter of catheter
pressure differences (change in fluid height - rate can increase if you raise fluid higher)
length of system components - longer = slower rate
viscosity of fluid

Question 21

STAT IV flow rates

Answer 21

14G - 5.25” - 13.1L/hr
12G - 26.9L/hr
10G - 36.5L/hr

Question 22

Typical STAT IV equine set up

Answer 22

8’ above horse head, 28L/hr gravity flow capacity

12 drops/ml

Question 23

Long term vs short term catheters

Answer 23

Long term: up to 14d, soft material, over wire placement, expensive, polyurethane or silicone

Short term: up to 72h, teflon and polyethylene

Question 24

catheter complications

Answer 24

thrombosis, cracking, breakage, air embolism, extravasation

Question 25

Rate of thrombosis dependent on

Answer 25

systemic state (coagulation status) of animal stiffness of catheter - more stiff more thrombogenic size of catheter - larger more thrombogenic length of catheter - more thrombogenic material - polypropylene = most thrombogenic, polyurethane (mila) = least thrombogenic vessel trauma

Question 26

air embolisms in IV catheters

Answer 26

death due to cardiac arrest if 3-8ml/kg of air in circulation

Question 27

typical acid-base disturbance in horse

Answer 27

metabolic acidosis

Question 28

2 electrolytes horses tend to lose

Answer 28

K and Ca

Question 29

Crystalloid fluids

Answer 29

most commonly used composition based on electrolytes and non-electrolyte solutes only replacement crystalloids: composition similar to ECF maintenance crystalloids: composition with less sodium and more potassium -LRS, Saline, Normosol, Plasmalyte, Dextrose, bicarbonate solution - hypertonic saline most commonly used in resuscitation, 7.2%HS

Question 30

Colloid fluids

Answer 30

if hypoproteinemia less commonly used recommended when need to increase oncotic force within IV space to retain fluid within that space - hetastarch, dextran, plasma, serum

Question 31

Fluid tonicity always named in reference to

Answer 31

plasma tonicity

Question 32

Isotonic fluids

Answer 32

includes most commonly used solutions

Question 33

hypotonic solutions

Answer 33

decreased tonicity compared to plasma | used in cases of plasma hyperosmolality

Question 34

hypertonic solutions

Answer 34

tonicity above plasma

Question 35

Hypertonic saline

Answer 35

resuscitation and emergency use hypovolemia MOA: fluid shift from intracellular space to ECF space associated with increased tonicity Effect: temporarily improves CO, MABP, urine production, decreases SVR - increases preload while decreases afterload Major disadvantages/contraindications: - rapid decay of effect, may combine with 6% dextran 70 - uncontrolled hemorrhage - renal failure, CV alterations, hypokalemia

Question 36

Calculate dehydration deficit

Answer 36

Deficit (L) = BW (kg) x % dehydration

Question 37

Calculate maintenance

Answer 37

Maintenance (ml) = BW(kg) x 60ml/kg/d divide by 1000 to get L

Question 38

5% dextrose infusion is like infusing

Answer 38

free water

Question 39

Typical equine fluid rate

Answer 39

10-20ml/kg/hr

Question 40

shock dose for horse

Answer 40

30-40L/hr

Question 41

degree dehydration and catheter size

Answer 41

if severe, recommend 10-12G or possibly 2 12-14G if moderate, 12-14G miniature horses and weanlings with moderate dehydration

Question 42

goal of replacing estimated deficits (time)

Answer 42

1-2h | can safely give 1 blood volume per hour

Question 43

24 hour fluid plan

Answer 43

incorporate maintenance, continued dehydration (if it exists, and estimated ongoing losses) dehydration (L) = % dehydration x BW maintenance = 50-60ml/kg/day ongoing losses - vomit, diarrhea, anything quantifiable

Question 44

Potassium

Answer 44

plasma level not good indicator of total body K, intracellular concentration better large amount ingested in diet so large amount excreted daily see large total body depletion in anorexia and colic

Question 45

hypokalemia

Answer 45

caused by decreased intake, sequestration loss, associated with alkalosis clinical effect: arrhythmias, myocardial dysfunction, weakness, decreased intestinal motility

Question 46

hyperkalemia

Answer 46

lab error - RBC rupture in sample associated with HYPP, acidosis, uroabdomen, acute oliguric renal failure clinical effect: cardiac arrhythmias, standstill (KCl can be used as euthanasia solution)

Question 47

Potassium supplementation

Answer 47

Max IV dose: 0.5mEq/kg/hr

Question 48

Calcium

Answer 48

highly protein bound to albumin most interested in maintaining ionized fraction to maintain normal physiologic functions *ionized Ca most accurately reflects Ca status* large amount in diet so large amount excreted in anorexia, see total body depletion of Ca

Question 49

Hypocalcemia

Answer 49

synchronous diaphragmatic flutter - Thumps functional abnormality of no clinical significance appears as hiccoughs hyper responsiveness of phrenic nerve Effects: muscle paresis, tremors, excitability, cramping, aggression, excitation, hypersensitivity, decreased myocardial contractility, hypotension

Question 50

3 things that can cause synchronous diaphragmatic flutter (thumps)

Answer 50

hypocalcemia hypokalemia metabolic alkalosis

Question 51

Hypercalcemia

Answer 51

seen in renal failure effects: toxic to cells, effects heart, kidneys, CNS, GIT cardiac arrhythmias, seizues, twitching

Question 52

Ca supplementation

Answer 52

recall decreased intake --> total body Ca deficit general 100-150ml Ca gluconate in fluids without bicarbonate SLOWLY recheck after giving half desired dose incompatible with tetracycline, IV lipids, bicarbonate give slo because cardiotoxicity if too rapid, bradycardia

Question 53

Magnesium

Answer 53

hypomagnesemia often associated to conditions leading to hypoK and hypoCa, may blunt response to Ca therapy can potentiate cardiac arrhythmias IV administration: Mg sulfate - vasodilator properties, dont give if hypotensive - IV slow as 10% solution if severe hypomagnesemia

Question 54

Sodium

Answer 54

typically reflect water balance, water follows Na | changes often concomitant with changes in Cl

Question 55

Determining type of fluid loss

Answer 55

hypertonic loss - loss of electrolytes in excess of water hypotonic loss - loss of water in excess of electrolytes isotonic loss - loss of electrolytes in same ratio as found in serum HORSE - typically has isotonic losses especially as it relates to GIT disease, horses exercising lose isotonic then as become more dehydrated losses become hypertonic

Question 56

Sodium disturbances

Answer 56

both hypo- and hyper-natremia cause CNS signs CS dependent on severity of Na alteration and speed of development Compensatory mechanism: within brain cells, adjust intracellular osmolality to equal to that of extracellular environment - only occurs if CHRONIC changes neurons create idiogenic osmoles to maintain osmolality and can destroy them Acute: recommended rapid restoration to normal Na status Chronic: rapid restoration can be detrimental due to compensatory mechanisms in play - can increase CNS intracellular volume = brain edema - outside compensated range, chronic still appears as if it were acute showing clinical signs

Question 57

Most common acid-base disturbance in horse

Answer 57

metabolic acidosis

Question 58

Quantitative analysis of acid base

Answer 58

for every 10mmHg increase in PCO2, there is corresponding 0.05 decrease in pH

Question 59

Metabolic acidosis

Answer 59

most common in horses caused by loss of bicarbonate or increase in acid - hyperchloremia - loss of base - increased anion gap - gain of acid (lactic acidosis, toxins, renal failure)

Question 60

Treatment of metabolic acidosis

Answer 60

use alkalinizing solution: buffer base in solution (LRS, normosol) typically lactate

Question 61

bicarbonate as Tx for metabolic acidosis

Answer 61

not used unless bicarb <17-18 or pH <7.2 never treat empirically to correct, need to measure actual level calculate deficit: deficit X distribution X bwt kg = ____mEq ``` Distribution factor: 0.3 conservative 0.4 typical 0.5 young animals Give 1/2 of dose over first hour then re-evaluate to avoid putting them into metabolic alkalosis ```

Question 62

Metabolic alkalosis

Answer 62

only occasionally, endurance racing (swear losses) also high GIT disease contributes to development of synchronous diaphragmatic flutter Treatment: acidifying solution (NaCl)

Question 63

Patterns of specific disturbances

Answer 63

Endurance - losses of Na, Cl especially, hypocalcemia and hypokalemia also seen - loss of Cl results in retention of bicarbonate and metabolic alkalosis (high pH) Choke - losses of Cl - results in retention of bicarbonate and metabolic alkalosis (high pH) General - most common alteration = metabolic acidosis