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.