Critical Care Medicine: Fluid Therapy Flashcards
What is the distinction/difference between hypovolemia and dehydration? What clinical signs are associated with each?
Dehydration is secondary to disease states caused by internal or external losses to the vascular or intracellular space. This can be caused by sequestration within the GIT, abdomen or thorax. It can also be caused by increased losses caused by diarrhea, renal failure, or extreme exercise with insufficient replacement .
Hypovolemia is decreased intravascular blood volume causing a loss of the ability to perfuse tissues.
Hypovolemic shock CS: Prolonged CRT (poor perfusion), decreased jugular filling, tachycardia, decreased pulse pressure, cold extremities, decreased skin turgor
What are the clinical indicators of need for fluid therapy?
Skin turgor: decreased in dehydrated states, typically when 8-10% or more dehydrated (normal = <1s)
Mucus membranes: dryness is seen when 5-7% dehrdrated, also look at color and CRT
Urine production: decreased production and increased USG if dehydrated unless has renal disease
Sunken eyes: ypical in ruminants when 8-10% dehydrated, in horses only if severe
Heart rate: expect tachycardia (seen early)
Jugular distensibility: decreased if dehydrated
Also: Depression and muscle weakness
What are the laboratory indicators of need for fluid therapy?
PCV + TP: for every increase in % dehydration over 5%, PCV increases 5% in horses, 3% in ruminants
(Splenocontraction can falsely elevate their PCV and make it seem more dehydrated if not anemic, but less dehydrated if truly anemic but anemia has been masked by splenocontraction)
TP typically >8 g/dL when >/= 10% dehydrated (normal = 6-8)
(If hypoprotenemia (e.g. GI sequestration) can underestimate degree of dehydration)
ALB: The only possible cause of hyperALB is dehydration; normal 2.3-3.9 and MUST stay above 1.5
Lactate: (esp good to monitor response to tx)
Urinalysis: BUN/CRE: evaluate urine, renal vs pre-renal; USG typically >1.030 but can get up >1.060
Describe the clinical parameters for an adult horse that is 5% (mildly) dehydrated
Skin tent: 1-3sec
MM: Could be slightly tacky
CRT: WNL (<2)
HR: WNL
Decreased urine output (Difficult to assess, esp if horse lives outside/on pasture)
Describe the clinical parameters for an adult horse that is 8% (moderately) dehydrated
Skin tent: 3-5sec
MM: Tacky
CRT: Variable; 2-3sec
HR: 40-60
Decreased arterial blood pressure
Describe the clinical parameters for an adult horse that is 10-12% (moderate to severely) dehydrated
Skin tent: 5+ sec
MM: Dry
CRT: Variable; >4 sec
HR: 60+
Reduced jugular fill
Barely detectable peripheral pulse
Describe the obvious clinical abnormalities for an adult horse that is 12-15% (severely) dehydrated. At what percent is death imminent?
Obvious sunken eyes (occurs closer to the higher end of the range)
Obvious shock
Death is imminent at 15%
What are the determinants of catheter thrombogenicity (TG) as applies to the horse?
- Systemic state: coagulation status, bad if endotoxemic or septic
- Stiffness of catheter: stiffer = more TG (HOWEVER flexible catheter with small diameter can cause vessel trauma (and thus thrombosis) if IVF rate is high)
- Length of catheter: longer = more TG
- Material of catheter: Polypropylene (AngioCath) = most TG; – polyethylene – Teflon – polyvinylchloride – silicon – nylon – Polyurethane(Mila)= least TG
What is the maximal rate of a STAT IV set at is hung 8’ above the heart of the horse?
28 L/hr
What is the maximal for rate (L/hr) of a 14G 5.25” IVC? What about a 12G? 10G?
14G (5.25”)= 13.1 L/hr
12G= 26.9 L/hr
10G= 36.5 L/hr
How much fluid you can administer at one time per os via nasogastric tube? What is the transit time from the stomach? What rate can you achieve via this route?
6-8 L (gastric capacity = 15L, but bever administer max due to risk of overfilling leading to shut down of GIT)
Transit time <30 min
Can achieve 12-16 L/hr
If you want the animal to drink of it’s own volition for rehydration, what type(s) of fluid must you provide?
Free water AND electrolyte solution
(never free e-lyte solution alone)
What are the advantages and disadvantages of oral fluid administration?
(+)
Most physiologic
Least expensive and invasive
Fewest complications
Helpful in LI impactions and overhydration techniques (when want to liquify resp secretions or increase flow of fluids through intestines)
(-) Reflux and ileus MAJOR C/O’s
What IVC is typically used for IVF and what veins are preferred? What are the advantages and disadvantages of intravenous fluid administration?
14G 5/5” Angiocath
Jugular and Lateral thoracic veins (Cephalic is first choice for limb
(+)
Easy access
High/unlimmited rate of administration possible
Easy adjustment in fluid plan
(-)
Risk of thrombosis, phlebitis and sepsis
Requires sterility and monitoring (often in hospital setting)
Expensive
SQ fluid administration can be helpful in foals but it rarely used. Why is SQ fluid administration nearly never used in adult horses?
Little to no loose skin
Where are IP fluids administered?
Dorsal aspect of the left flank at the paralumbar fossa
(Cecum is on the right, don’t poke the damn cecum)
What are the advantages and disadvantages to intraperitoneal fluid administration?
(+)
Can potentially give large volumes quickly
Easy access, not much equiptment needed
Good alternative to IV
(-)
PRACTICALLY cannot give large volumes (causes abdominal discomform at as little as 10L)
Must monitor closely, especially for sepsis
How are fluids administered per rectum?
Gravity flow pump with horse standing on incline (to prevent evacuation reflex)
What are the advantages and disadvantages of rectal fluid administration?
(+)
No special equipment or sterility needed
Many formulations ok
Large volume quickly
Good alternative to IV and PO
(-)
Not helpful with ileus
Cannot be used if colicy or has diarrhea
(Also you could get shit all over yourself)
What are the advantages and disadvantages of intra-osseous fluid administration?
(+)
Good if veins complromised
Great for pot-belly pigs
Good in foals if other methods C/O’d
Good if no jugular filling
(-)
Requires special IO needles
Technically more difficult
Limited rate (max 2L/hr, depending on needle size)
What are the advantages and disadvantages of intra-cecal fluid administration?
(+) Large volumes directly into segment of intestines w/greatest absorption
(-) More invasive and requires aspesis
When are hypertonic crystalloid fluids recommended? Give an example of this solution.
Giving 2L of hypertonic solution quickly is equivalent to how many L of isotonic solution? How long does this last?
What can you do to increase the duration?
Hypertonic Saline (typically 7-7.4%, but defined as anything over 0.9% NaCl):
- If more e-lytes than water are lost (hypertonic losses)
- When want a rapid increase in CO
- When want to draw fluid from the 3rd space and intracellular environemnt = DECREASES TOTAL PERIPHERAL RESISTANCE
- To stimulate a CNS response favoring CV stability in the short term (mitigated by 3rd ventricle in brain)
Giving 2L of hypertinic saline in no longer than 10 min = 20L of isotonic fluids
- Adding 6% Dextran 70 (a colloid) to the solution improves the duration of effect
What adverse reactions are associated with hypertonic saline? Are they common?
What are the contraindications?
Hemolysis will occur if the solution is not placed in a large vessel (Infusing into peripheral vessel is C/O’d )
Arrythmias/ VPCs (usually only high high % sln)
ADVERSE REACTIONS ARE RARE
C/O’s:
Uncontrolled hemorrhage
Severe hypernatremia
Severe hypokalemia
Note: Dehydration is not a C/O as long as it is not associated with a significant hypernatremia, dehydration does make the solution less effective.
What types of fluids (specific) could you give to a horse who has lost more water than electrolytes?
Hypotonic solution - 0.45% NaCl
When is the administration of colloids recommended?
When we need to increase oncotic force within the IV space to retain fluid within that space
Indicated for hypoproteinemia
Examples: Hetastarch, Dextran (40 or 70), Plasma, Serum
What lab indicators are good for evaluating how well your fluid therapy is working? What does comparing these values reveal?
PCV and TP
View TP as whole number (remove the decimal), if that number is close to or less than the PCV value this is bad
It indicates that the fluid cannot be administered quickly enough (proteins are being diluted out)
Must balance rate to ensure reasonable hydration without overdiluting proteins.
What is the formula for the amount of volume needed to rehydrate/hydrate a patient?
D + M + O
(Deficit +Maintenance + Ongoing losses )
Where D= % Dehydration x BW (kg)
M= 50-60 ml/kg/day (30ml/lb)
What is the general recommendation for replacing the fluid deficit in a horse? Why?
Replace the deficit within the first hour
(High-Volume Recuscitation)
Why? To normalize the ciruclating volume to prevent further systemic deterioration.
What % of a horse’s body weight is blood? How much fluid, as it relates to blood volume, can generally be administered in one hour?
8%
1 blood volume (80 ml/kg/hr)
Which 2 systems must you consider/evaluate when deciding whether to give a horse a large amount of fluid in short time period? Are these systems often dysfunctional in horses? What is the most important thing to check?
Cardiac
Renal
No, horses rarely get heart or kidney dysfunction
Protein Level= most important in horses
What is the maximum shock dose for a horse?
60-90 ml/kg/hr
The typical set-up for IVF administration in a horse consists of ___ 5L bags suspended from a pulley system with a ‘pivoting wheel’. The____ ___ IV set is typically used.
A large-bore coil set then attaches to an ________ or ______.
The rate of flow is dependent on the distance between the _______ and the _________.
The typical set-up for IVF administration in a horse consists of FOUR 5L bags suspended from a pulley system with a ‘pivoting wheel’. The MILA STAT IV set is typically used.
A large-bore coil set then attaches to an IV CATHETER or EXTENSION SET.
The rate of flow is dependent on the distance between the BOTTOM OF THE BAG and the BASE OF THE HEART.
What 3 gauges of catheter are used in horses? Which one is most commonly used and is it 3.25”, 4.25” or 5.25” long?
14G, 12G, and 10G
14G 5.25”
T/F: A pump is used to regulate the amount of IVF a horse is receiving.
False, a free flow system
How can leakage around the IVC cause neurologic dysfunction? What type of dysfunction?
Damage to the recurrent laryngeal nearves can lead to laryngeal hemiplasia (Roaring)
What drug causes severe sloughing if it extravasates upon administration?
Phenylbutazone (NSAID)
What occurs with acute bilateral jugular thrombosis? What do you do if you notice this occuring?
Facial edema resulting in nasal occlusion
Elevate head and use something to keep nares open
What is the consequence of an endurance horse developing jugular thormbosis?
Will compromise his athletic ability, induce exersize intolerance (Degree depeidng on severity)
Give some examples of isotonic IVFs
LRS
Normasol
Sodium and chloride usually change in (the same/opposite) direction(S) and reflect (hydration state/ water balance).
Sodium and chloride usually change in THE SAME DIRECTION and reflect WATER BALANCE
What does it indicate when chloride is normal but sodium is decreased? What is this condition called?
That chloride is being retained probably due to bicarbonate loss (to maintain electoneutrality)
Hyperchloremic Metablic Acidosis
In the face of metablic acidosis, bcarbonate supplementation is warrented. How do you calculate the deficit? At what level do you not supplement bicarb but rather administer LRS, knowing the horse will probably self-correct?
Normal = 24 (-30) mEq/L
Use conservative distribution, so for an adult-
Deficit = (24 - Measured) x 0.3
(Foal: (24-M)x 0.5)
Administer 1/2 in over 1 hour, then reassess
> or = 17-18 mEq/L expect horse to self-correct
What electolyte deficiency do you expect if a horse goes off feed? What does this mean in terms of fluid administration?
Potassium
Always supplement IVF with K (even it the K+ is normal on BW)
Horses are geared to consuming and eliminating a lot of potassium and calcium, this is evidenced by the fact that the formation of these is normal in horses.
Calcium urinary crystals
What is the maximum K rate in horses?
0.5 mEq/ kg/ hr
(Generally 10-20mEq/L)
What alterations do you expect in a horse with a long standing esophageal obstruction who has been losing saliva for a long time (or a horse who has an esophagostomy tube)?
Hypochloremia
Hyponatremia
Metabolic alkalosis
What anticipated alterations may you see in an endurance horse after a long race?
What is this combination of alterations associated with?
Hypocalcemia
Hypokalemia
Metabolic alkalosis
Associated with SDF (Synchronous Diaphragmatic Flutter) (typically bilateral)
Which alteration seen in endurance horses is most associated with the development of SDF? What nerve does it affect and how?
What clinical signs are associated with SDF?
Hypocalcemia
Phrenic nerve- causes hyperexcitability, it contracts with every atrial contraction
CS: Hiccups, muscle paresis, tremors, excitability, cramping, behavior changes (agression, hypersensitivity, disorientation), hypotension; It will seem like HR=RR
What alterations do you expect with a horse who has colic?
Hypovolemia
Metabolic acidosis
Usually ISOTONIC e-lyte/water changes
If a horse presents with a moderate to severe case of diarrhea is inappetent but drinking water, what alterations do you anticipate?
Dilution of all electolytes
Metabolic acidosis
What diseases/conditions cause large amounts of protein loss? How would this affect your fluid plan?
Colitis
Peritonitis
Pleuritis
Must supplement protein- plasma transfusion ($$$), Hetastarch (for moderate losses)
As it relates to GIT disease, typically horses have ______ fluid losses.
Isotonic
T/F: Both hypo- and hypernatremia cause neurological dysfunction in the horse.
True
How do brain cells prevent fluid shifts from occuring when they are faced with slowly, progressively decreasing sodim in the intravascular/ intersitital space?
Compenstory decrease in neuronal intracellular tonicity by destroying “idiogenic osmoles”
How will you correct a horse who presents with acute hypernatremia? What is your goal?
Administer: Isotonic saline, Hypotonic saline, D5W
Goal: Drop Na as fast as possible
How will you correct a horse who presents with clincal signs (behavioral abnormalities) associated with chronic hypernatremia? Over what time period do you want to normalize the sodium?
Get sodium to the edge of the compensatory level as quickly as possible, then bring Na to a normal level over 1 week
What can you add to improve the Carbinocentric model of AB analysis (Carbinocentric Model)?
Anion Gap (AG) analysis
- Anion Gap = Sodium - (Chloride + Bicarbonate)*
- (Bicarb = TCO2 or CO2)*
For every 10mmHg increase in CO2, what change in pH do you expect?
So if you have a sheep with a pCO2 = 80 mmHg, what is the predicted pH?
A decrease of 0.05
pH= 7.2
Calculation:
KNOW: Normal pCO2= 40mmHg, Normal pH= 7.4
- 80-40=40 (So 4 increments of 10mmHg)*
- 4 x 0.05 = 0.2 (Change in pH)*
- 7.4-0.2= 7.2*
When might it be advised/helpful to overhydrate a patient?
Impactions
Liquifaction of respiratory secretions to facilitate expectoration
(Usually done by increasing M rate, e.g. x2)
