Fluid therapy Flashcards
CS of dehydration
- skin tent
- sunken eyes
- tacky mm
Time frame for restoring fluid deficit
- 12-24h
Fluid maintenance
= 2ml/kg/hr
Insensible fluid losses calculation
= 0.5-1ml/kg/hr
CS of hypovolaemia
- slow CRT
- pale mm
- cold -> extremities & low rectal temp
- tachycardia
- weak peripheral pulses
CS of distributive shock (septic shock)
- fast CRT
- red mm
- high rectal temp
- tachycardia
- weak/bounding peripheral pulses
Why do you get bounding peripheral pulses with septic shock?
- diastolic pressure has stopped
- therefore systolic has to pump harder to bring the mean up
- but drops back down massively again for diastolic
- so you feel the big pressure difference
Normal lactate
- <2.0mmol/L
Normal MAP
- > 60mmgHg
How to differentiate hypovolaemia vs sepsis
- CS similar
- can be both e.g. with acute haemorrhagic d+ and septic bacterial translocation
- tx trial i.e. tx for hypovolaemia, if doesn’t get better tx for sepsis
Treatment test for hypovolaemia vs sepsis
- monitor BP (q5mins)
- monitor lactate (q2-3h)
- can also monitor PCV & TP
- bolus therapy over 10-15mins (cat 5-10ml/kg, dog 10-15ml/kg)
- if BP still low after initial bolus give another
- if BP still low give another
- if BP still low, hypovolaemia is not the problem -> probably distributive shock
Why is BP poor for pts with distributive shock?
- vasodilation
How to tx low BP for pts with distributive shock? (& how these drugs help)
- vasopressors e.g. norepinephrine/noradrenaline (cause vasoconstriction)
- dobutamine (positive ionotrope, helps with cardiac contraction)
- dopamine (vasoconstrictive and cardiac, but rarely used as can promote tachyarrhythmias which can be life threatening for septic pts)
all given CRI
- start at lowest end of dose range and titrate up if necessary
- if get to the top of the dose and still no effect -> other problem with the vessels caused by sepsis -> vessels get leaky
- to help maintain the vessels fluid and stop them leaking give oncotic support
What are colloids?
- synthetic molecules that mimic albumin inside the blood vessels
Use of colloids
- if put into leaky vessels i.e. with septic pt it will leak out into the interstitium nd cause renal oedema, reducing renal function
– increased rate of AKI when colloids are used - surviving sepsis guidelines don’t support the use of colloids
How to provide oncotic support
plasma transfusion
- dog specific approach as don’t have cat plasma widely available
How to measure ongoing losses
- weight bedding
- Foley catheter
- urinary catheter
- weigh pt
Why is Hartmann’s the isotonic fluid of choice?
- alkalinising & most of our pts will be acidotic, whereas saline is acidifying
What is the target weight % deficit for CHF cases?
- 5%
What can vasopressors damage at high doses?
- peripheral tissues e.g. distal limbs
Clinpath signs associated with <5% fluid deficit
- no clinically detectable signs
Clinpath signs associated with 5-7% fluid deficit
- mild depression
- slightly prolonged CRT
- slightly increased HR
- increased blood lactate
- increased creatinine concentration / concentrated urine
Clinpath signs associated with 10% fluid deficit
- depressed
- may have cold extremities
- dry mm with CRT >3s
- HR >50% above normal ref range
- increased blood lactate
- increased creatinine concentration
- small volume of very concentrated urine
Clinpath signs associated with 12-15% fluid deficit
- depressed
- cold extremities
- dry mm with CRT >4s
- HR >100% above normal ref range
- increased blood lactate
- increased creatinine concentration
- unlikely to produce any urine
