I can't move my legs
What do NMB agents do?
They are peripherally acting muscle relaxants that reversibly block the neuromuscular junctions.
Succinylcholine facts and effects
Facts: only depolarizing agent in use, first causes muscle fasciculations and then flaccid paralysis, has a rapid onset with short duration, there is no reversal
Effects: causes muscle soreness, brady OR tachycardia, arteral hypotension, arrhythmias, and hyperkalemia
What TOF must be present for reversals to be administered?
3
Where / how are amides and ester boned anesthetics metabolized?
Amide: liver (all of its drugs have 2 i's in them)
Ester: plasma cholinesterases (all of its drugs have 1 i in them)
What can you give to "absorb" excess LA?
IV lipid emulsion
What do NMB NOT do?
They cause no sedation or unconciousness, do not cross the blood brain barrier or placenta, and have no analgesic effects.
Non-depolarizing NMB facts
Facts: short (<20min), intermediate (20-50min), long (>50min) acting options, potency is inversely related to their onset (more potent = slower onset), reversal = anticholinesterase (neostigmine or edrophonium)
What should you pair with your reversals? What are you trying to avoid?
Glycopyrollate with neostigmine or atropine with edrophonium
Avoiding: side effects of stimulation of postganglionic parasympathetic muscarinic receptors (bradycardia, bronchoconstriction, etc.)
How is pKa related to onset of action?
The higher the pKa, the slower the onset
How long do you fast and withold water from ruminants?
Fasting: 48 hours (24 hours for small ruminants)
Water: 24 hours
What are the 3 main indications for NMB?
Thoracic sx: to prevent fighting the vent
Ortho sx: facilitate reduction of dislocated joints and fractures
Ocular sx: keep eye central
Atracurium and cisatracurium facts and effects
Facts: intermediate acting non-depol, IV bolus or infusion, broken down by hofmann degredation, used in hepatopathy and nephropathy patients
Atra effects: arterial hypotension from histamine release (cisatra has a lower propensity to do this)
How do local anesthetics work? Uses?
Reversibly block generation and propagation of electrical impulses in nerves
Uses:desensitize area of body form topical, infiltration, nerve block, epidural, or for antiarrhythmic, prokinetic, MAC reduction, and analgesia
What is ion trapping? Why is it important?
Fetal pH is lower than maternal so ionized forms of drugs get trapped in the placenta, since local anesthetics are weak bases they get trapped in acids, use with caution in pregnant animals
When should anticholingergics be administered to ruminants?
ONLY for treatment of bradycardia, giving to "dry up" secretions just makes them thicker and can lead to bloat
What are the 3 MOA of NMBs?
Competitive binding (classic), desensitization (channel does not respond to Ach), and channel blockade (prevents flow of ions in open channel).
Order of muscular paralysis
What channel do local anesthetics effect?
Block voltage gated Na+ channels
What can be added to prolong a LA? Shorten the onset?
Prolong:epinephrine or alpha2 agonists
Shorter onset: hyaluronidase or sodium bicarbonate
What is special about alpha 2 agonists in large ruminants?
The are VERY sensitive and only require 1/10 equine dose, can also cause abortion due to it's oxytoxcin like effects
What are the 2 main types of NMBs?
Both competitive. Depolarizing (persistent depolarization WITHOUT repolarization) & non-depolarizing (will not depolarize)
How much neuromuscular transmission has to fail before you can detect a change? Complete failure?
70%, 90%
What order do local anesthetics work in?
Vasodilation, sensory inhibition, motor inhibition
What order does LA toxicity go in?
CNS, respiratory, then cardiovascular
Can you give alpha 2 agonists to small ruminants?
No, causes pulmonary edema