Anesthesia Flashcards
ASA 1 and example
Healthy
Elective SX- spay/neuter
ASA II
Mild systemic disease
Mass removal, uncomplicated ortho procedure, well controlled diabetic
ASA III and example
Severe systemic disease
Cardiac dysfunction, poorly controlled DM, mild anemia, early renal disease
ASA IV and example
Severe disease this is constant life threat
Hemoabdomen, sepsis, FB, shock, hypovolemia
ASA V and example
Moribund patient who is not expected to survive without operations
MAssive trauma, multiorgan dysfunciton
What is the grimace scale
Discriminates painful vs nonpainful
five action units - eyes, ears, muzzle whiskers, head position in cats
What is the UNESP Botucatu MCPS
First pain scale to be validated for post-op pain in cats
Looks at 10 different variables
Recuse analgesia required if total >7/30
What is Glasgow
Pain scale for cats
Can be applied to any pain
Rescue analgesia >5/20
What is transduction
conversion of noxious stimulus into electrical energy by peripheral nociceptor
Mechanical pain to electrical
Transmission
impulse propagation from the site of the oral injury through the CN V
Modulation
When neurons from the pain fibers synapse with nociceptive neurons in the medulla
What is wind up pain
Peripheral sensitization remains untreated and the exacerbation of intensity of the nociception
Glutamate binds to NMDA = increase pain (this is why ketamine helps with wind up)
What analgesics affect transduction, transmission and modulation
- Transduction - local anesthetic, opiod, NSAID, Steroids
- Transmission - local anesthetics, Alpha2 Agonist
- Modulation - local anesthetic, alpha 2 agonist, opiods, NMDA antagonist, anticonvulsants, NSAID
How does hyperalgesia, analgesia, allodynia effect pain and the stimulus curve
- hyperalgesia - increase responsiveness, shift curve to the left
- Analgesia- decreases response, shiftst curve to the right and flattens it
- Allodynia - innocuous stimuli begin to elicit pain, shifts curve to the farthest left
What is the purpose of the anesthesia machine and circuit
safe delivery of inhalants and O2 with removal of CO2 and excess gases
What is normal tidal volume
10-15ml/kg
What is solubility (anesthetic gas)
Usually expressed as coefficient known as ostwalds coefficient
The greater blood gas partition coefficient = great solubility in the blood
increased solubility = longer induction recovery times
What is the most to least soluble anesthetic gases
Halothane>ISO>SEVO>Nitrous oxide>Desflurane
Inhalant effects on the body
CNS - depression via inhibitory GABA, NMDA, AMPA
Resp - depression
CV - Decrease CO, hypotension, vasodilation
Kidney - decrease renal BF
Liver - mild
Malignant hyperthermia
Minimum alveolar concentration
of inhalant: produces no response in 50% of animals exposed to noxious stimulus
1MAC = light anesthesia
1.5MAC = surgical
2MAC = deep
0.5MAC = awake
MAC of Sevo vs Iso
Sevo = 2.3
Iso = 1.3
What are the 4 stages of anesthesia
1 = induction to loss of consciousness
2 = excitement, spontaneous muscle movement
3 = end of spont muscle mvt and regular breathing
3a= light, regular breathing, pupil size normal, ventromedial, some response
3b= medium, shallow breathing, moderate pupil size, ventromedial, minimal palpebral, no response
3c= deep, jerky breathing, dilated and central pulse, decreased corneal reflex
4 = extreme CNS depression and respiratory arrest
How much of the body is water
55-60%
Blood volume is about how much? how to calculate transfusion
90ml/kg
ml of donor blood = recipient blood volume x desired PCV - active pcv/pcv of donor
P wave seen on ECG
atrial depolarization
PR interval represents
atrial depolarization adn conduction of AV node
QRS complex represents
ventricular depolarization
TT represents on ECG
repolarization
AV block type 1: if r is far from P
second degree av block type 1: wenkenback: PR gets longer, longer, drops
Second degree av block type 2: mobitz: P waves dont produce QRS response. Intermittent QRS dropped
3rd degree av block: P and Q dont agree
Sinus arrhythmia
Ventricular enlargement alters QRS
VPC
Ventricular enlargement alters QRS
ventricular Tachy
Hypoventilation causes
increased CO2
Respiratory acidosis
hypo-ventilating to increase bicarb
Hyperventilation causes
Decreased CO2
Respiratory alkalosis
trying to decrease bicarb
What are the 4 phases of capnography
1 = dead space
2 = expiratory
3 = alveolar plateau
4 = Inspiratory
What is normal end tidal CO2
35-45mmHg
>45 = hypoventilation
Normal
Hypoventilation
Obstruction
Check equipment
endotracheal cuff
hyperventilation
What happens with hyperkalemia
bradycardia
peaked t waves
prolonged PR
Loss p waves
Wide QRS
What happens with lidocaine toxicity
5- muscle twitching
10 - seizures
15- unconsciousness
20+ = seizure, coma, resp arrest, cv depression
Is MAC lower or higher for neonates
Lower
What are the 4 types of anaphylactic reactions
1 - immediate
2 - cytotoxic
3 - immune complex
4 - delayed
Atropine and glyco are what types of drugs
Anticholinergics
Atropine - crosses BBB, can see av block, fast
Glyco - doesnt cross BBB, slower, decrease saliva
Both act on smooth muscle relaxation
What do adrenergic receptors do
improve cardiac output by increasing HR and SV
Increase BP by vasoconstriction
What do the adrenergic receptors work on (A1, A2, B1, B2, B3)
Alpha = contraction
Beta = relaxation
A1= contract smooth muscle
A2= nerve terminals
B1= heart and kidney
B2= smooth muscle relax
B3= adipose tissue
What are the MOA for Norepi vs Epi
Epi = high affinity for beta receptors, increase CO
Norepi = high affinity for alpha receptors, primarily used for hypotension due to decreased vascular resistance
Dopamine vs dobutamine
Dopamine = alpha and beta receptors, 5-20mcg/kg/min
Dobutamine = beta receptors agonist, used for low CO, 10mcg/kg/min
what is CO
CO = SV + HR
What is naloxone, atipamezole, flumazenil reverse
naloxone = opiod
atipamizole = alpha 2 agonist
Flumazenil = Benzodiazepine
Maximum dose of Lidocaine/bupivicaine
Bup = 2mg/kg
Lidocaine = 3-5mg/kg
Projection vs perception
Projection = dorsal horn to cortex
Perception = realizing painful stimuli
Evaporation, conduction, convection, radiation loss
Evaporation = dissipatiton of heat via moistture to gas
Conduction = transfer between 2 objections
Convection = transfer within fluids
Radiation = through electromagnetic waves
Half life
Time for plasma concentration to decrease by 50%
MOA of Nerve Block
Blocks NA channels
70% or 3 nodes of ranvier
lipophilic, hyrdophilic joined by ester or amide linkage
acidic environment causes longer onset due to ionization
Adverse effect of bupivicaine and other NB
cardiotoxic (more so bup)
CNS issues
Methemoglobinemia –tx methylene blue
Toxic dose of lidocaine vs bupivicaine
Lido = 10mg/kg
Bupivicaine = 2mg/kg
IO blocks what
Desensitizes teeth, maxilla, incisive bone, upper lip, oral mucosa
**extent depends on how caudal the needle is
MX NB blacks what
Desensitizes maxilla, incisive bone, palate, maxillary teeth, gingiva, oral mucosa, nasal mucosa (partially), skin
Inferior alveolar blocks what
Desensitizes mandibular body, mandibular teeth, surrounding oral mucosa, lower lip
Mental foramen (middle) blocks what
Desensitizes rostral lower lip & oral mucosa if the foramen is not entered
Desensitizes incisor, canine, & most rostral premolar teeth if foramen is entered; desensitization is partial even then
Major Palatine block what
Desensitizes soft tissues & bone of hard palate rostral to the block on the ipsilateral side
What is the order from shortest to longest acting local anesthetics (lido, bup, mepiv, ropiv)
Lido = 2 hour
Mepiv = 2-4 hr
Bupiv = 4-6 hours
Ropiv = 6+ hour
What are examples of alpha 2 adrenoreceptor agonist and their reversal
Dexmedetomine and medetomidine
Reversal = atipamezole
What is an example of alpha 2 agonist and reversal
Xylazine
Reversal - atipamezole
Sedation, analgesia, muscle relaxant, decrease MAC
Example of Benzodiazepine and reversal
Diazepam and midazolam
Reversal - flumazenile
Anxiolytic/anticonvulsant - depresses thr limbic system through GABA
Example of Phenothiazine
Acepromazine
Dopamine receptor agonist and is metabolized through the liver
Neuroactive steroid
Alfaxalone
Inhibits GABA
Anticholinergic agents
Atropine and Glyco
Hypnotic alkyl phenol
Propofol
interaction with GABA potentiating the gaba induced chloride
Ketamine
Interacts with multiple binding sites including NMDA & non-NMDA glutamate receptors, nicotinic & muscarinic cholinergic, monoaminergic & opioid receptors
Inhibits voltage-dependent sodium & calcium channels
Cerenia
Antiemetic and prokinetic
Maropitant is an NK-1 receptor antagonist that blocks the action of substance P in the central nervous system as well as at peripheral NK-1 receptors in the GI tract
Metoclopramide
Antiemetic
MOA not well understood
what are the three classes of opiod receptors and MOA
Activity at opioid receptors located in the CNS & peripheral sites (ganglia & peripheral nerve endings)
3 classes of opioid receptors:
Mu (MOP)
Delta (DOP)
Kappa (KOP)
What are the four classification of opiod and examples of each
- Agonists
High affinity for mu
Morphine, pethidine, hydromorphone, methadone, fentanyl, sufentanil, alfentanil, remifentanil, codeine
Tramadol is a weak mu agonist - Partial Agonists
Do not have full intrinsic activity at the mu receptor
Buprenorphine - Mixed Agonist-Antagonists
Act as agonists at some receptors and antagonists at others
Affinity & intrinsic activity at the receptor site may vary
Butorphanol - Antagonists
Reverse the effects of mu and kappa agonists because of their high affinity & low intrinsic activity
Naloxone
What is the pathway of desensitization of nerve blocks
B are desensitized first, then C, then A-delta, then A-beta. A-alpha are the largest nerves, so motor is blocked last/not at all. Re-sensitization happens in reverse order
