Fluid Therapy Flashcards
(38 cards)
1
Q
what do fluid dynamics depend on?
A
- osmotic pressure
- oncotic pressure
- hydrostatic pressure: exerted by fluid pressing on capillary/cell walls
- reflection coefficient
2
Q
describe fluid therapy
A
- replacement of losses
-resuscitation
-rehydration
-ongoing excessive losses - providing maintenance fluids
- as a vehicle for drugs and electrolytes
3
Q
what are the 2 categories of fluids?
A
- crystalloids
-isotonic replacement
-maintenance
-hypertonic - colloids:
-biologic
-synthetic
4
Q
describe crystalloids
A
- water-based solutions
- contain small osmotically active molecules which are permeable to membranes
- crystalloids redistribute!
-less than 1/3 left in vascular space after 30-40 min = good for replacing vascular volume! AKA shock
5
Q
how are crystalloids characterized?
A
- tonicity
- buffer content: acidifying versus alkalinizing
-the only acidifying solution is normal saline
-alkalinizing solutions have added buffers to increase pH - electrolyte content
-balanced versus unbalanced
–balanced solutions have added electrolytes to closer mimic plasma composition
-replacement versus maintenance
–replacement solutions have a similar sodium content to that of normal (for replacement!)
–maintenance solutions are much lower in sodium (half strength of replacement) and contain electrolytes to maintain daily homeostasis
6
Q
describe the 3 categories of tonicity
A
- isotonic: general use
- hypertonic: used for resuscitation, pulls fluid into vasculature
- hypotonic: free water replacement
-5% dextrose: maintains some osmolality but is metabolized quickly so left with free water, used to treat hypernatremia SLOWLY
7
Q
what is the most commonly used fluid solution!
A
isotonic, balanced, replacement crystalloid!!!
when in doubt reach for one of these
8
Q
describe hypertonic crystalloids
A
- osmotic pull from interstitium
- hypertonic saline: primarily for resuscitation or for intracranial edema
- hypertonic bicarbonate: ONLY IN CALVES!!!!!!! with severe diarrhea!!!!
9
Q
what are 2 contraindications of hypertonic saline?
A
- dehydration:
-if interstitially dehydrated, nothing to pull fluid from, will just make patient salty - hyper or hyponatremia (sodium derangement)
-hyper: duh
-hypo: don’t want to raise too fast and risk brain injury
-how know? chronic vomiting or diarrhea = check first
-HBC? probs normal before smacked by car so probs safe to use
10
Q
give 5 potential side effects of hypertonic saline
A
- dehydration
- hypernatremia
- bradycardia: if give really fast, rapid increase in afterload/blood volume = reflex bradycardia
- hypotension
- bronchoconstriction: if give too fast
-give these nice and slow, over like 10-15 min as opposed to a rapid bolus
11
Q
describe how to choose a crystalloid
A
- fluid plan
- serum sodium level
- acidemia versus alkalemia
- calcium levels
- concurrent drug therapy
-precipitation = so so bad - liver disease
12
Q
what are 3 potential side effects of crystalloids?
A
- exceeding starling curve: giving more water will no longer result in an increase in stroke volume, leads to fluid overload
- fluid overload:
-edema, effusion
-GI stasis - dilutional coagulopathy: harder time finding each other when so diluted = harder to clot, rare in animals
13
Q
what is the primary difference between a replacement and a maintenance crystalloid solution?
A
sodium concentration!
14
Q
define colloid fluids
A
large molecules that are restricted to the plasma compartment = too large to leave, which is good because the fluid stays where you put it (great for shock)
provide oncotic pressure/support:
-innate: from the molecule itself
-gibbs-donan effect: molecule is negatively charged so attracts Na+ which attracts water
15
Q
describe the available colloids
A
- biologic:
-plasma
-albumin: canine, human - synthetic:
-hydroxyethylstarches
-gelatins
16
Q
describe uses for plasma
A
- primary use is to provide clotting factors
-but hard to find and expensive - hypoalbuminemia: inefficient to treat, too expensive to provide enough albumin most times unless animal super small or not crazy losses
- providing immunoglobulins
-primarily foals who fail passive transfer
-or puppies and kittens
-early calves!!
17
Q
describe potential side effects of plasma
A
- transfusion reactions
- fluid overload: colloids stay where you put them, so is hard to redistribute large volumes to vascular space
18
Q
describe the 5 functions of albumin
A
- contributes 80% of oncotic pressure
- drug carrier
- bilirubin and FFA carrier
- anti-inflammatory
- anti-coagulant
19
Q
describe albumin replacement
A
- need species-specific bc very immunogenic
-only canine available - human albumin also available
20
Q
describe uses for albumin
A
- treat severe hypoproteinemia (primarily in dogs)
- shock poorly responsive to crystalloids
-but takes a whole to reconstitute so not very practical for ER unless last option left
21
Q
describe the possible side effects of albumin
A
- fluid overload: very concentrated product will pool fluid and is hard to redistribute
- tranfusion reactions:
-ESPECIALLY with human product!
-facial edema, anaphylaxis, vomiting, fever, delayed immune-mediated disease, death
22
Q
describe synthetic colloids
A
hydroxyethylstarches (HES)
-polysaccharide similar to glycogen, primarily amylopectin
-the larger the molecule the longer the half life
-degree of substitution: average number of hydroxyethyl groups per glucose unit within the polymer (hetastarch, pentastarch, etc.)
23
Q
describe uses for hydroxyethylstarch
A
- plasma volume expansion
-resuscitation
-vascular leak: septic patients have pulled apart endothelium (changed reflection coefficient; so large molecules are more likely to stay in vascular space than smaller) - oncotic support
-hypoproteinemia
24
Q
describe 6 potential side effects of HES
A
septic patients are far more likely to experience side effects!!
- fluid overload:
-if using a lot of colloids early in resuscitation plan, will drop subsequent crystalloid rate by 1/2 to see how body will handle it at first - anaphylactoid reaction: not IgE mediated but something that resembles histamine release
- pruritis: molecules hang out in tissues for a long time, less intense in vet med
- coagulopathy
-platelets: coats platelets = can’t adhere to each other
-vWF, VIII
-dilutional
-if a patient has low platelets or rodenticide tox or some other coagulopathy defect, DONT USE - acute kidney injury
-dose dependent, very bad in humans, not usually seen in animals but still beware - increased mortality:
-if on cardiac bypass or septic
25
what are the 4 parts of a fluid therapy plan
1. resuscitation
2. rehydration
3. maintenance
4. ongoing losses
26
describe resuscitation
1. must be completed FIRST before considering the rest of the plan
2. fluids for this:
-isotonic replacement crystalloids: REPLACEMENT FLUIDS ONLY
-do NOT use maintenance solutions for shock!!!!!!
-hypertonic saline: 7.2% (8x normal saline sodium concentration) is most common, super salty
-colloids: HES, sometimes plasma or albumin
-RBCs: for severe anemia
27
describe use of isotonic replacement colloids in resuscitation
1. give 1/4 to 1/3 of TOTAL shock dose over 15 minutes or more conservative as needed (murmur, etc.)
-cat/camelid: 50-60ml/kg total, 10-15ml/kg shock bolus
-dog, ruminant, horses: 90 ml/kg total, 20-30ml/kg shock bolus
-birds: 60-120 ml/kg total, 10-15 ml/kg shock bolus
-reptiles: 70 ml/kg total, 10 ml/kg shock bolus
-MEMORIZE above numbers
-total shock dose is approx patient blood volume, give a 1/4-1/3 for shock bolus and then monitor
2. beware of redistribution: if hypovolemic, really want it to stay in vascular space but it will try to get out to interstitium and could reshock, so recheck and continue monitoring as needed
28
describe the use of hypertonic saline for resuscitation
1. use for severe shock, traumatic brain injury, or for small volume resuscitation of very large patients
2. bolus size = 3-5 ml/kg
3. repeat once, if necessary
-recheck sodium if you want to give more
4. DONT USE IF: severe dehydration or severe sodium derangement
29
describe use of HES in resuscitation
1. for hypoproteinemic or decompensatory shock failing fluids alone
2. bolus of approx 5ml/kg
-up to 15ml/lg in cats and camellids
-up to 20 ml/kg in dogs, horses, ruminants, most others
30
describe maintenance needs
1. to maintain homeostasis
-normal losses: so use lower sodium fluids
2. optimally replaced using maintenance crystalloids
-sometimes use replacement crystalloids fro simplicity (one bag versus multiple) but NOT if heart disease (use low sodium), renal insufficiency (use maintenance solution for sure)
3. 50ish ml/kg/day for most
-40-50 for cats and camellids
-50-60 for most others
-NEONATES much higher!! can't concentrate urine yet so need 2-3x adult rate!
31
describe the tonicity of losses and the fluid of choice to replace losses/rehydration
losses are generally high in sodium and electrolytes so use balanced, isotonic, replacement crystalloids for rehydration/replacement!
32
describe assessment of dehydration
1. cannot detect less than 5% dehydration in ANY patient!!
2. so if you detect any signs of dehydration, they are AT LEAST 5% dehydration
3. for dehydration replacement, take weight in kg x % dehydration (ex. 16kg x 0.1 for 10% dehydration) and replace over 12-24 hours
4. if less than 5% dehydrated and treating as outpatient, can utilize SQ fluid option
-top out at 20ml/kg in any one admin, reassess and readmin PRN
for the rest, will have a chart on an exam :)
33
describe HES for non-shock use
1. hypoprotenemia
2. hetastarch: 1ml/kg/hr, 20 ml/kg/day
3. tetrastarch: up to 50ml/kg/day
-much smaller molecule so excreted more rapidly so higher dose
34
describe ongoing losses
1. EXCESSIVE losses
-vomiting/reflux, diarrhea
-urinary losses
-third spacing
2. quantify losses
-measure
-estimate amount loss: 1 gram = 1ml with a pee pad
-weigh animal, more common in large animal (rapid changes in body weight are water changes)
3. generally, losses are high in electrolytes, so use REPLACEMENT crystalloids
35
describe the routes of fluid admin
1. enteral
-voluntary
-tube/gavage
2. per rectum: horses, ruminants
3. subcutaneous
4. intraperitoneal/intracoelomic
5. IV
6. interosseous
36
describe potassium supplementation
1. for all hypokelamic patients
2. for normokalemic patients especially if not eating
3. based on serum K+ level
4. Kmax is 0.5mEq/kg/hr
37
describe dextrose supplementation
1. to prevent or treat hypoglycemia
2. bolus if severely hypoglycemic
-0.25-0.5g 50% dextrose/kg diluted
3. CRI
-usually 2.5 or 5%
-solution is now hypertonic if added to replacement solution
--use a central catheter if >5%
4. not enough to meet caloric needs!
38
describe bicarbonate administration
1. for SEVERE METABOLIC acidosis
-NEVER respiratory acidosis
2. controversial; treat the underlying cause of acidosis first
3. indications:
-pH <7.1
-bicarbonate of <8-12mEq/L
-symptomatic
4. administer SLOWLY IV
5. complications:
-paradoxic CNS acidosis
-hypernatremia
-hypokalemia
-worsening intracellular acidosis
