Fluid therapy Flashcards
Crystalloid
Contains small molecules
isotonic crystalloid purpose
To manage dehydration and hypovolaemia
isotonic crystalloid examples
Hartmanns, 0.9% NaCl
Colloid
contains large molecules that can’t cross semi-perm membranes
5 routes of fluid admin
Per os (mouth)
sub cut
IV
central venous access
IO
Volume overload symptoms (hypervolaemia)
dyspnoea, tachypnoea, crackles
Venous engorgement symptoms
jugular distension, peripheral oedema, cavitary effusions
fluid distribution
60% is water- 55% extravascular- 40% inside cells, 15% outside cells
hypovolaemia vs dehydration
hypovolaemia is fluid lost quickly from the intravascular space, dehydration is fluid lost slowly from extravascular space
consequences of hypovolaemia
blood loss-> reduced preload-> reduced stroke volume-> decreased CO-> vasoconstriction and tachycardia-> BP drop
patient assessment of IV volume
HR
pulse quality
MM colour
CRT (>2secs)
BP
mentation (mental status)
temp
patient assessment of extravascular volume
moistness of MM
skin turgor
weight
globe position
urine output
clinicopathological parameters
PCV, TS
urea, creatinine
USG
shock
an imbalance between oxygen delivery to the tissues and oxygen consumption by the tissues
4 types of shock
hypovolaemia
cardiogenic
obstructive (tension pneumothorax, thromboembolism)
distributive (uncontrolled inflammatory response)
physiological response to hypovolaemic shock
neurohormonal response:
- catecholamine release (increases HR, vasoconstriction)
- activation of renin-angiotension-aldosterone system (increases Na + water retention
- ADH release
- spleen contraction (releases more RBC)
steps for use of isotonic crystalloids
- bolus of fluid 10-20ml/kg for dogs, 5-15ml/kg for cats over 15-20mins
- reassess
- admin 45-50ml/kg max for dogs, 30-35ml/kg max for cats
- if no change, reassess diagnosis and ongoing blood loss
shock dose (total blood vol of patient)
80-90ml/kg in dogs
50-55ml/kg in cats
determining efficacy of fluid therapy treatment
- reassess every 12-30mins
- bp (could be compensatory)
- lactate levels
- ECG (monitor arrythmias)
hypertonic fluid uses
- common in large animals
- lowers initial vol reqiured for vol resus
- reduces cerebral oedema
large animal fluid resus
1L hypertonic fluid followed with 10L isotonic fluid
- stomach tube/IV
indications for colloid fluid therapy
tissue oedema, hypovolaemia, low oncotic pressure
signs of dehydration
tachy MM, slow CRT, sunken eyes, bradycardia
osmotic pressure
the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane
oncotic pressure
a form of osmotic pressure induced by the proteins in a blood vessel’s plasma which causes a pull on fluid back into the capillary
indications for blood testing in patients recieving fluid therapy
for all animals sick enough to warrant hospitalisation and fluid therapy
- every 24-48hrs
- sooner if signs of complications
blood tests that should be considered using in dogs and cats recieving fluid therapy
- PCV and TS
- blood urea nitrogen and creatinine
- urine specific gravity (USG)
- lactate
- glucose
- electrolytes
- acid-base status
3 electrolytes
- sodium
- potassium
- chloride
causes of hyperkalaemia
- urethral obstruction
- uroabdomen
- hypoadrenocorticism
- renal failure
managing hyperkalaemia
- IVFT (dilutes K+ in blood)
- calcium gluconate (stabilises myocardium)
- glucose +/- soluble insulin (potassium -> intracellular spaces)
- treat underlying cause
causes of hypokalaemia
- GI tract losses (vomiting, diarrhoea)
- urinary tract losses, diuretics
managing hypokalaemia
- address underlying cause
- K+ supplementation
- KCl can be added to fluid therapy
metabolic acidosis causes
- loss of base from the body
- failure to excrete acid
- accumulation of acid
metabolic acidosis body compensation
body counteracts this by blowing off CO2 through hyperventilation
- will have low pH and pCO2
metabolic alkalosis causes
- increase in hydrogen bicarbonate loevels
- loss of acid from body
metabolic alkalosis body compensation
hypoventilation which lowers pH
respiratory acidosis causes
a rise in blood CO2
- upper airway obstruction
- pulmonary effusion (fluid on the lungs)
- pulmonary disease
- CNS depression
respiratory acidosis body compensation
- kidneys retain more bicarbonate and excrete H+ ions to increase pH
respiratory alkalosis causes
a fall in blood CO2
- fear, pain, excitement, pyrexia
- hyperventilation
respiratory alkalosis body compensation
- eliminate bicarbonate via kidneys to lower pH
fluid therapy preferrable for acidotic patients
hartmann’s
- contains lactate as a buffer
fluid therapy preferrable for alkalotic patients
0.9% NaCl
- slightly acidic
