anesthetic drug protocols Flashcards
drug class ketamine
NMDA-receptor antagonist
ketamine mode of action
Dissociative general anaesthetic (amnesia and anaesthesia)
ketamine indication
-analgesia
-anestesia for short procedures
ketamine side effects
-Seizures
-Tissue irritation
-May demonstrate bizarre behaviour on recovery (volcalisation of cats)
-Increased salivation and respiratory tract secretions
ketamine contraindication/precaution/ warming
-Increased intracranial pressure
-History of seizures
-Pre-existing heart disease
ketamine reversable? controlled?
not reversable. controlled drug
alfaxalone drug class
Intravenous steroid anaesthetic
alfaxalone mode of action
Neuroactive steroid with properties of a general anaesthetic
alfaxalone indication
-Intravenous induction agent in dogs and cats; can be given im for heavy sedation
-Can be used to maintain anaesthesia
alfaxalone side effects
Transient respiratory depression and apnea
Cardiac arrhythmias
alfaxalone contraindication/ precaution/ warning
Not to be used with other injectable GA agents
Must only be given when endotracheal intubation, oxygen support and ventilation can be administered
No analgesic properties: provide sufficient pain relief
alfaxalone controlled? reversable?
controlled, not reversable
propofol drug class
Intravenous general anaesthetic
propofol mode of action
Short-acting injectable hypnotic GA agent
propofol indications
-Intravenous induction agent in dogs and cats
-Can be used to maintain anaesthesia
propofol side effects
Bradycardia, hypotension
Transient respiratory depression **
possible seizure- like activity
propofol containdication/ side effects/ warming
Hypersensitivity
Must only be used when patient can be supported
Dose decrease needed when patients have been pre-medicated
propofol reversable? controlled?
not reversable, controlled
comparing propofol and alfaxalone, when is propofol used over alfaxalone?
vet preference (propofol has been used longer)
-cheaper
Not controlled everywhere, alfaxalone always controlled)
what are the two inhalant general anesthesia
isoflurane, sevoflurane (usually used for maintanace)
inidcation of iso and sevo
Induction and maintenance of general anaesthesia
what is Minimum Alveoli concentration (MAC)
Standard index of anaesthetic potency for inhalation anaesthetics
Corresponds to the effective dose 50 (ED50) (amt of drug needed to cause 50% of population to go to sleep)
Lower MAC= lower % of gas needed (more potent)
iso has lower MAC-> lower precentage of gas is required to acheive and maintain surgical anesthesia
MAC: amount of inhalation GA needed in alveoli (lungs) to cause sleepyess
tell me about blood: gas partition coefficient
Blood/gas solubility coefficient
Predicts the speed of anaesthetic induction, recovery and change of anaesthetic depth
Low blood: gas PC ( means less gas goes in blood means s gas can faster get out of the blood and go to the brain ) = increased speed
extra info:
Low Partition Coefficient = Less soluble in blood = The gas doesn’t dissolve much in the blood.
Blood saturates (does hold on to the gas for long) quickly, so the gas moves into the brain faster.
difference and similarity bwtween iso and sevo
both: induction and maintainance of GA
minimum alveolar concentration (MAC) (%) (potency of drug)
MAC: iso D: 1.5, C: 1.2 (less drug need to g to sleep) sevo D: 2.1-2.4, C 2.6
rate of anesthethic induction and recovery ( Blood; gas partition coefficient): iso: slower (1.4) , sevo: faster (0.6)
odor and respiraotry irritation: iso: strong odor, more irritating sevo: less ordor, less irritating (harder to detect for leaks-> more dangerous)
mode of action:
-CNS depression (relaxes, keeps patient asleep)
-Depression of body temperature regulation centre (rem patient feel cold-> we use blanket)
-Respiratory depression (effect of CNS depression)
-Hypotension (low BP)
-Muscular relaxation (needed for surgery)
caution/warning:
-rapid changes in depth of anaesthesia can occur (15-30s)
-Must only be used when patient can be supported (monitoring by vet tech)
cost: iso cheeper than sevo (newer, to update to sevo is more exp-> need to buy new parts)
difference and similarity bwtween iso and sevo (indication)
both: induction and maintainance of GA
difference and similarity bwtween iso and sevo (MAC)
minimum alveolar concentration (MAC) (%) (potency of drug)
iso Dog: 1.5, cat: 1.2 (less drug need to g to sleep)
sevo Dog: 2.1-2.4, Cat 2.6 (less potent)
why even following MAC, patient may wake up
cos MAC corresponds to the effective dose (ED50)-> estimate, this percentage may not be effective to them
difference and similarity bwtween iso and sevo (rate of anesthetic induction and recovery)
iso: slower (blood/gas partial coeffcient: 1.4)
sevo: faster 0.6
difference and similarity bwtween iso and sevo (odour and respiratory irritation)
iso: strong odour, more irritating
sevo: minimal odour, less irritating
difference and similarity bwtween iso and sevo (mode of action)
both
-CNS depression (relaxes, keeps patient asleep)
-Depression of body temperature regulation centre (rem patient feel cold-> we use blanket)
-Respiratory depression (effect of CNS depression)
-Hypotension (low BP)
-Muscular relaxation (needed for surgery)
difference and similarity bwtween iso and sevo (caution/warning)
both
rapid changes in depth of anesthesia can occur
must only be used when patient can be supported
what is GA (fyi)
general anesthesia is a drug-induced unconsciousness that is characterised by controlled but reversable depression of the CNS (if u stop giving GA, patient will wake up) and perception
includes
-anesthesia
-analgesia
-depressed reflex resonses (immobalised)
if they under the right stage of GA tehy are not aroused by noxious stimulus (things that cause themto experience pain/ discomfort)
what are the four stages of GA
I, voluntary excitement
II. involuntary excitement
III. surgical anesthetic
plane 1-light
plane 2- medium (surgical)
plane 3- deep
plan 4-rocking boat
IV: over dose
tell me about stage I: voluntary excitement
-immediately after administration of inhalation/induction agent
state: conscious nut disorientated (confused)
-reduced sensitivity to pain
vitals:
-respiration and heart rate normal (all vitals still normal)
reflexes: all still present
(palperbral-touching corner of eye, blinking, jaw tone: resistance to opening of mouth)
SEMI AWAKE
tell me about state II: involuntary excitement
-exhibit excitement (rapid movement of legs, vocalisation of struggle)
vitals: irregular breathing, may appear to hold breath
stage 2 end: muscle relaxation, slower respiration, decreased reflex activity (going to sleep) (palperbal: blink slowly/absent. jaw tone: can open mouth easily)
-transient (transition to sleep) can be minimised by administering induction drug slowly.
TRANSIENT STAGE- happens too quickly that we can miss it
Stage III, plane 1-light
-involuntary movements (twitching)
(uncoscious, but will move/react to painful stimulus (cannot start surgery yet)
vitals: respiration rate becomes regular
reflexes:
-gagging and swallowing relfexes are depressed (can intubate, wont choke on it)
-palpebrebral: present but slow
-pupillary light reflex: diminished (not much response)
eyes: start to rotate ventrally (look down)
-pupils may become partially constricted
INTUBATE
stage III, plan 2: medium
-surgical stimulation (when performing surgery), evoke mild response but remain unconscious and immobile (Ideal stage for surgery)
-more relaxed muscle tone (perfect for surgery-> easier to cut)
vitals: respiration is regular but shallow
heart rate, blood presuure mildly decreased
relfexes: most are diminished
-pupilary light response is sluggish (pupil doesnt rly constrict)
eyes: central-ventral medial (looking down/crossed eyed)
pupils are slightly dilated
IDEAL FOR MOST SURGERY
stage III, plane 3-deep
-deeply anesthetized
vitals: depression of circulation (pulse rate) & respiration is often present
-ventilation assitance (manual breaths)
-heart rate is reduced, even in the presence of surgical stimulus (eg cutting, noxious stimulus)
relex: pupillary light: poor/absent
reflex activity is absent
jaw tone is slacked
eyes: central (staring straight at u)
-pupils are moderately dilated
stage III. plane 4
-spasmodic, jerking inspirations (breathe they will move/jerk)
-muscle tone flaccid (soft)
vitals: obvious depression of cardiovascular system, dramatic drop in heart rate and blood pressure, pale mucos membrane (CNS depression)
reflexes: pupillary light reflex: absent
eyes: dry eyes
fully dilated pupils
stage IV: overdose
-cessation of respiration
-circulatory collapse and death (heart goes haywire-beat too fast/slow)
-immediate resuscitation is necessary
when is induction of anesthesia done
20-30 min after pre med-> pre med is fully effectivly (all used up-> reduce amt of induction agent, shows us how asleep patient is ) (adter premed)
techniques (how) is anesthesia induced
-IV injection
-IM injection
-by mask
considerations of iv injection (how/when/where to use)
-intravenous acess (IV catheter)
-level of sedation/tranquiliser (too low-unsafe)
-patient temprement biting- cannot do IV)
-length and type of procedure (pocedure need fast acting)
important tips for IM injcetion
-palpate muscle to ensure you locate your landmarks
-after inseting needle, draw back plunger to ensure it hasnt accidentally gone into vein
im injcetion can hurt:
be gentle, rubbing the injection site can help
IM injection sites
quadriceps muscles (back leg muscle)
lumbodorsal muscle (muscle beside spine)
procedure of iduing with inhalation gas using anesthetic mask
Procedure:
Pre-medicate patient, and wait 20- 30 mins (for full effect of pre med)
Connect the mask to the anaesthetic circuit
Turn on oxygen only and place mask over patient’s muzzle
2-3 minutes (to pre-oxygenate patient-> to increase o2 reserve for when anesthesia affects breathing, theres is sufficent /extra 02)
3-4L/min ( approx 30 times tidal volume)
Turn on the vapouriser to deliver anaesthetic gas
Increase the concentration of anaesthetic in 0.5% increments until 3-4% reached
consideration of inducing via inhalation agents
Patient is likely to go through an excitatory phase. (gas takes longer to put patient to sleep)
Ensure the patient is well restrained (become resless while waiting to fall asleep)
Monitor the patient closely for any signs of respiratory distress
Eg. Purple MM, altered respiratory patterns (not getting enough 02)
Once sufficiently anaesthetised, the patient should be intubated (more maintainance)
when is anesthetic chambers used
Only appropriate for very small patients
Reserved for the most uncooperative patients
Possible contamination of environment with anaesthetic gas
Difficult to monitor HR, RR and other vitals z9hence only used as a last resort)
procedure of indcution using anesthetic chamber
Conscious patient placed inside chamber
Oxygen is delivered through an inlet
Anaesthetic gas delivered at 4-5% with 3-5L/min of oxygen
Transferred to table and intubated once unconscious
