Therapy of shock Flashcards
Why can fluid therapy be dangerous?
- starling’s equation determines fluid movement in healthy animals but this can be altered if an animal is ill
Which patients are at risk of fluid overload?
- cardiac dz
- pulmonary dz
- oliguric/anuric renal failure
- geriatric cats (undetected dz)
- hypoalbuminaemia
- sepsis/ SIRS
What happens when we give too much fluid?
- pulmonary oedema
- interstitial oedema (SC oedema, oedema of organs –> decreased function)
- 3rd space loss
CS -fluid overload
- pulmonary crackles (generalised)
- RR and RE
- peripheral oedema
- chemosis of eyes
- bilateral serous nasal discharge
- jugular distension/pulsation
- increase in body weight
- large L atrium on US
Where are you wanting fluids to disperse in a. shock and b. dehydration?
a. intravascular space
b. interstitial space
When should you tx for shock?
tx until 6 perfusion parameters are normal
How much is too much to give?
no more than one blood volume:
dog 80ml/kg
cat 50ml/kg
Components - fluid prescription
- fluid type
- dose rate (dose - shock, rate - dehydration)
- additives
- how to deliver
- when to stop
Name 3 types of crystalloid
- ISOTONIC (hartmann’s, CSL, LRS, 0.9% NaCl)
- HYPERTONIC (7.5% NaCl)
- HYPOTONIC (0.45% NaCl, 5% dextrose)
Name 2 types of colloid
- SYNTHETIC (Volulyte)
- NATURAL (blood products, albumin)
Which fluids aren’t used to tx shock?
hypotonic
What are balanced crystalloids
contain Na, K and lactate
Why is there lactate in isotonic crystalloids?
metabolised to bicarbonate –> neutralises blood so treats metabolic acidosis (which occurs in shock)
Why do Isotonic crystalloids contain K+?
doesn’t usually cause hyperkalaemia (so can be used even if K+ in blood is slightly high), because diuresis causes increased renal excretion
Why do isotonic crystalloids contain Ca?
calcium chelates with sodium citrate preservative in blood products so DON’T give in same IV line unless you flush line through first with saline`
Indication - isotonic crystalloid
- hypovolaemic shock (all causes
- obstructive shock
- vasodilatory shock
- dehydration/ maintenance
- diuresis (azotaemia, toxicity)
- tx metabolic acidosis (hartmann’s, CSL, LRS)
- tx metabolic alkalosis (0.9% NaCl)
What crystalloid dose for dogs and cats?
- DOG: 10-20ml/kg IV
- CAT: 5-10ml/kg IV
- deliver over 15 minutes
- repeat up to 4 times (monitor 6 perfusion parameters/ fluid overload).
How many times should you repeat an isotonic crystalloid therapy?
If no improvement after 2 doses –> STOP!
Indications - hypertonic saline
- traumatic brain injury
- cerebral oedema
- large breed dog
- CPR
Contraindications - hypertonic saline
- if patient is originally hyper or hyponatraemic
- dehydration
Dose - hypertonic saline - 7.5% NaCl
- 2-4ml/kg over 10 mins
- bolus or CRI
- only once
- follow with isotonic crystalloids
Indications - artificial colloids
- severe hyperproteinaemia
- large dog
Adverse effects - artificial colloids
- kidney injury
- coagulopathy
- increased risk of fluid overload
Contraindications - artificial colloids
- coagulopathy
- renal failure
- sepsis (as animals are more prone to kidney injury)
Dose - artificial colloids
- DOG 5-10ml/kg over 15 minutes
- CAT 2.5-5ml/kg over 15 minutes
- repeat up to 4 times
How do we deliver IVFT?
- medium-large dogs: pressure bag
- small-medium dog: fluid pump
- cats: careful of fluid overload, 50ml syringe by hand, syringe driver, fluid pump with paediatric burette
Components of continuous fluid therapy
- maintenance
- dehydration
- ongoing losses
Maintenance - define
- normal daily fluid requirement
- isotonic crystalloids: Hartmann’s, LRS, CSL, 0.9% NaCl
- rate 2ml/kg/hr
CS - dehydration
not detectable
CS - dehydration 5-8%
slight increase in skin tent
possible tacky MM
CS - dehydration 8-10%
- definite increase skin tent
- tacky MM
- dry tear film
CS - dehydration 10-12%
- greater skin tenting
- tacky MM
- sunken eyes
- shock
What is the equation for dehydration replacement?
Total replacement amount (ml) = % dehydration/100 * BW * 1000
- administer over 8-24 hours
What are ongoing losses?
- V/ D
- 3rd space loss (cavity effusions)
- wounds
- PU
What rate for fluids is given for ongoing losses?
- measure/weigh: vomit, diarrhoea, urine
- estimate 0.5-1.5* maintenance (low - for mild losses, higher end - more severe cases)
Indications - hypotonic crystalloids
hypernatraemia only (NOT for maintenance of shock)
Why add potassium chloride?
- hypokalaemia (V, D, PU)
- don’t exceed >0.5mmol/l/kg/hr as high K can be toxic
When add potassium phosphate to fluids?
hypophosphataemia (e.g. DKA)
Why add dextrose to fluids?
hypoglycaemia
Other than IV, how can fluids be given?
- oral
- SC
- intraosseous
What happens to fluid given to the intravascular space?
3/4 redistributes in the interstitial space (sometimes this is not what you want)
