Equine Field Anesthesia Flashcards
what patient history is important
- signalment
- medical history
- anesthesia relevent information (prev anesthesia, time of last meal, allergies/intolerances)
- physical exam
what is the pre-anesthetic preparation
- starvation period (not for suckling neonates)
- patient weight
- IV access
- wash out mouth with water
- clip the surgical area
why is IV access essential
top ups and emergency drugs
irritant drugs (thiopentone, guaifenesin)
what is an example premedication recipe
- acepromazine: 10-30 micrograms/kg IM 40-60 mins prior to induction
- NSAIDs +/- antibiotics
- romifidine 40-100 micrograms/kg IV (detomidine, xylazine) + butorphanol 20-50 micrograms IV or morphine 0.1-0.2 mg/kg slow IV
how is induction done
free fall
swing gate
controlled recumbency if possible
keep owners away
what is used for induction
- ketamine/benzodiazepine
standard protocol
reliable and controlled
prior sedation mandatory
what is an example induction recipe
- ketamine 2.2 mg/kg + diazepam 50 micrograms/kg
mix in same syringe
what is the equine triple drop
500 ml GGE + ketamine + alpha 2 agonist
- 500 ml GGE 10% + ketamine 1500 mg + xylazine 750 mg (starting rate 0.66 ml/kg/h)
- 500 ml GGE 10% + ketamine 1000 mg + detomidine 10 mg (starting rate 1 ml/kg/h)
what are the advantages of the triple drip (3)
- easy
- cardiovascular function increases
- respiratory funciton increases (increased PaO2 and decreased PaCO2), preservation of hypoxic pulmonary vasoconstriction
what are the triple drip disadvantages (4)
- horses appear to be light: swalloing, blinking, twitching (ketamine effect is not indicative of inadequate anesthesia)
- respiratory pattern changes with TD overdose (can be confused with inadequate anesthesia)
- for 90 min max
- drug accumulation: poor recoveries possible
what would a goo anesthetic protocol be for a 18 month TBX colt for a standard castration (not standing)
short procedures
standard premedication
induction: ketamine/diazepam ~ 20 min recumbency (not 20 min surgical anestheisa)
usually adequate for experienced vet
what would a good anesthetic protocol be for a 12 year old TB with penetrating sinus injury that requires exam and flushing under GA
should take 30-40 min
longer acting alpha 2 agonists (not xylazine)
standard induction
q(7-)10 min: 1/3 induction dose of ketamine –> regardless of how horse looks
max of 3 top ups
OR
triple drip
what would a good anesthetic protocol be for an 8 y TBX that requires GA to remove a splint bone fracture
60-90 min procedure
triple drip technique
standard sedation and induction
tendency to use same alpha 2 agonist for premed and triple drip
infusion rate initially at set rate and then adjusted to effect
what is important in procedures longer than >60 mins
ideally ability to ventilate
otherwise atelectasis formation –> dead space and V/Q mismatch increases and potential for hypercapnia and hypoxemia
what are the advantages to intubation
- airway maintenance and protection
- IPPV possible if large animal ventilator available
- easy to perform
