IVFT Flashcards
Perfusion parameters of vasoconstrictive shock
- Obtunded
- MM colour: pale-white
- CRT >2
- HR: tachy in dogs, either in cats
- Weak-thready pulses
- Cold extremities
Perfusion parameters of vasodilatory shock
- Obtunded
- hyperaemic mm
- <1s CRT
- HR: tachy in dogs, either in cats
- Bounding pulses
- Warm extremities
How is total body water divided between the body compartments?
1/3 ECF and 2/3 ICF
w/in ECF 1/4 IV and 3/4 Interstitial
how are osmolality and osmolarity different?
Osmolality = mOsm/kg of solution Osmolarity = mOsm/L of solution
Define hyperosmolar
osmolality greater than plasma
Define hyposmolar
osmolality less than plasma
what is an ineffective osmole?
crosses the cell membrane freely and thus does not draw water out of the ICF
How do hypotonic fluids effect water moves?
water moves out of the ECF and into the ICF
how do hypertonic fluids effect water moves?
water moves out of the ICF and into the ECF
what are the 3 arms of starling’s forces?
- Hydrostatic pressure
- Oncotic pressure
- Endothelial permeability
define hydrostatic pressure
pressure generated w/in the capillary by the fluid w/in and directly proportional to volume
define oncotic pressure
a pressure gradient generated by the presence of numerous colloid molecules that do not readily cross the capillary endothelium
abnormal fluid losses are usually…
isosmolar (w/ the same salt conc. as the plasma) thus it is only lost from the ECF compartment
water will only move from the ICF when ??? changes
osmolality
free water loss can occur if..
kidneys are not functioning (and anti-diuretic hormone not doing its job) + decreased water intake
3 types of shock
- circulatory
- hypoxic
- metabolic
types of circulatory shock
- hypovolaemic (+haemorrhagic)
- obstructive
- cardiogenic
- distributive/vasodilatory
causes of hypovolaemic shock
loss of salty water/plasma from the IV space eg. severe dehydration, rapid loss of plasma into the GIT, body cavity, interstitial space
causes of obstructive shock
when flow of blood bak into the right atrium, or from the right atrium to the left is prevented by physical obstruction
eg. pericardial effusion leading to right atrial tamponade, gastric dilation and volvulus (gas distended stomach compresses the CdVC and potentially the portal vein), severe PTE, severe heartworm infestation obstructing flow out of the right heart
causes of cardiogenic shock
disease of the myocardium itself
eg. DCM, endotoxin and cytokine release during sepsis, severe brady/tachyarrythmias
cause of vasodilatory/distributive shock
cytokines and other vasoactive mediators released w/ systemic inflam/anaphylaxis can cause endothelial dysfunction and dilation of the systemic arteries and arterioles, decreasing SVR
perfusion parameters of moderate vasoconstrictive shock
- mod-severe obtundation
- MM pale
- 2-3s CRT
- HR: increased/ poss. dec in cats
- Weak/poor pulses
- cool extremities
++ decreased BP
perfusion parameters of moderate vasodilatory shock
- Mod - severely obtunded
- MM hyperaemic
- <1sec CRT
- HR: inc/ poss dec. in cats
- Bounding to normal
- warm extremities
++ systolic and diastolic BP decreased
Describe the pulse quality and blood pressure in severe shock (vasoconstrictive or dilatory)?
non-palpable pulses, unable to read BP
list 3 isotonic crystalloids
- 0.9% NaCl
- Compounded sodium lactate (Hartmanns)
- Plasmalyte-148
shock volume for IVFT in dogs
20ml/kg
shock volume for IVFT in cats
15ml/kg
adverse effects of crystalloid fluids
- large volumes required and pattern of distribution may result in haemodilution effects + interstitial oedema
- rapid IV crystalloid fluid therapy may cause damage to the inner lining of blood vessels and perpetuate inflm and endothelial ‘leakiness’–> further tissue oedema
- potentially harmful - lung dysfunction dt 75% of dose ending up in the interstitium
list 3 colloid solutions
- albumin
- voluven/volulyte
- gelofusine
indications to use colloid solutions
patients with low COP (esp. those w/ acute protein losses)
synthetic colloid fluid dose
5ml/kg
max dose over 1 day is 20ml/kg for dogs
adverse effects of colloids
- possible inc. risk of AKI, platelet and coag. dysfunction
- anaphylaxis + hypersensitivities
- artificial inc. USG, Total plasma protein
max dose of hypertonic saline
6ml/kg over 5 min
uses of hypertonic saline
large animals in shock whilst allowing time for large volumes of crystalloids to be infused
indicators to use a vasopressor
- Patient received 50% BV IVFT and signs of vasodilatory shock
- Patient received full BV IVFT and still hypotensive
- Evidence of fluid overload (jug. distension, serous nasal discharge, chemosis) + hypotensive
- Septic shock suspected
weak-moderate vasopressor
dopamine
strong vasopressors eg.
- norepinephrine
- phenylephrine
- epinephrine (adrenaline)
- vasopressin
CS of 10-12% dehydrated
marked prolongation of skin tent, dry mm, dry conjunctiva and sunken eyes. Animal may also start to show signs of hypovol.
CS of 5% dehydrated
minimal amount of dehydration detected on PE; tacky mm, reduced tear film
CS of 6-9% dehydrated
delayed skin tent, tacky-dry mm, reduced tear film
which increases first with severe dehydration - urea or creatinine?
urea
DDx for inc. PCV
splenic contraction during stress, dehydration
Stepwise Qs to ask when formulating a fluid plan?
- Shock - type and severity
- Dehydration - %
- Lyte imbalances
- Metabolic acid-base
- Other: anaemia, hypoproteinaemia, XS losses
- Predisposition to overload - anuric/oliguric w/ AKI, cardiac disease
- Route and timeframe
Steps to estimate the deficit volume
BW X % dehydrated = L
Rate: 6-12hr w/ acute dehydration (dog) and otherwise healthy, 12-24hr if CDV/renal disease
Cats 8-24hrs
Maintenance rate of small dog
4ml/kg/hr
Maintenance rate of large dog/cat
2ml/kg/hr
estimate ongoing abnormal losses w/ severe vomiting (1x/hr)
1-2x maintenance
estimate ongoing abnormal losses w/ moderate vom (q6h)
0.5xmaintenance
vom once very 12hrs ongoing losses rate?
0.25 maintenance
examples of isotonic fluid loss
V+/D+
PU
Fluid accumulation in third space - GIT space, peritoneal, pleural
example of hypotonic loss
- secretory D+ eg. neonatal D+ in calves
- third spacing of water into the GIT after ingesting hyperosmolar material ie salt/paintballs
example of hypertonic losses
patients w/ hypoA and aldosterone deficit –> lack of ability to retain sodium and conserve water –> obliate PU and more rapid dehydration if that patient is also anorexic, + V/D+ (dt reduced circulating cortisol)
indications to use 0.9%NaCl
- hypercalcaemia
- metabolic alkalosis (dilutes XS bicarb w/ chloride)
indications to use LRS
- correcting metabolic acidosis
indications to use plasmalyte-148
- hypomagnesaemia
- severe liver dysfunction unable to metabolise lactate - as uses gluconate and acetate as bicarb precursor
how does 0.45% NaCl + 2.5% dextrose behave?
Half strength sodium’ (half normal ECF sodium conc.) about half the V of fluid being given will act like replacement fluid for ECF and half will behave as free water once the glucose molecules are metabolised.
