Anesthesia Final

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Terms in this set (...)

Barbituate
Thiopenta-Na (Family Of Drug)
Barbituate
Methohexital (Family of Drug)
Cyclohexamine
Ketamine (Family of Drug)
Cyclohexamine
Tiletamine (Family of Drug)
Simple to give
Very Little Equipement Needed
No explosion or pollution hazard
Non-Irritant to airway
Injectable Anesthetics (Advantages)
Possible Tissue Irritation (if given outside vein)
No recall of drug
Depth not easily altered as a sole anesthetic
Airway may not be provided
Drug may be cumulative in body tissues
Recovery
Induction can cause apnea
Elimination
Injectable Anesthetics (Disadvantages)
Mostly IV
IM
IP
Injectable Anesthetic (Routes)
Immediate Effect
Easier to titrate to effect
Good for irritant to tissues drugs (Barbiturates)
IV Admin (Reason for Use)
Requires more restraint, asepsis and skill
IV Admin (Disadvantage)
For difficult patients and/or species
IM Admin (Reason for Use)
Cannot titrate to effect
IM Admin (Disadvantage)
Only on patients that a vein isn't possible to get
i.e. Rodents and Neonates
IP Admin (Reason for Use)
Induction (*allow intubation)
Increase Analgesia
Maintain Anesthesia
Quickly Re-establish Anesthetic Plane
Injectable Anesthetics (Reason for Use)
Perfusion rate to brain and tissues
Distribution
Metabolism
Elimination
IV Admin (Factors which Affect)
Faster
Higher Lipid Soluibilty= _________ it gets to tissues
Schedule III
Barbituates (Class)
Induction
General Anesthesia
Sedative
*Anti-Convulsant
*Euthanasia
Barbituates (Reason for Use)
Thiopental and Methohexital
Short Acting Barbituates (Drugs)
Most Lipid soluble
Short Acting Barbituates (Solubility)
Pentobarbital
Intermediate Acting Barbituates (Drug)
Phenobarbital
Long Acting Barbituates (Drug)
Least Lipid Soluble
Long Acting Barbituates (Solubility)
More Lipid Soluble = Rapid absorption of drug
Barbituates (Onset of Action)
Once blood levels drop agent leaves brain and re-enters blood to muscles, fat and tissues- metabolized part by part by liver
Redistribution effect
CNS Depression
Anti-Convulsant
Excitement during induction and recovery
Barbituates (CNS Effects)
Most profound respiratory depression (depresses response to rising CO2)
Apnea
More Drug= More depression
Barbituates (Respiratory Effects)
Support ventilation
(healthy patient will survive)
If moderately overdose on Barbiturates and apnea accurs, what do you do?
Depresses the Myocardium resulting in decress Cardiac Output= Hypotension
Increased heart sensitivity to the action of Epinephrine (VPC's)
Barbituates (Cardiopulmonary Effects)
Hypoproteinemic (Can't bind)
Acidotic (Can't bind)
Lean Animals (sight hounds)
Liver Disease (cant biotransform)
Renal Failure (cant excrete)
Felines (lack metobolic enzymes)
Barbituates (Class of Patients Sensitive to this type of Drug)
<3 g/dl
To Hypoproteinemic for barbituates
Stop Injection
Keep Negative Pressure on Syringe while withdrawing
Inject 2x volume of Isotonic Saline (0.9% NaCl) into area
+/- Lidocaine for pain
Notify Vet
Watch for signs of irritation/sloughing
(more fluid if nessecary)
Barbituates (Steps to Take incase Admin outside vein)
Local swelling
Pain
Necrosis
Tisssue sloughing
Scaring
Barbituates (Signs that occur after perivascular injection)
Stage II Excitement
Hypothermia
Barbituates (Side Effects)
give 1/3 rapidly then titrate to effect (apnea at first)
How to avoid stage II excitement phase while giving barbituates?
Thiopental (Pentothal)
Methohexital (Brevital)
Most common barbiturates used in vet med for induction of anesthesia?
Pentothal
Thiopental (Brand Name)
Comes in a powder form
Reconstitutes 1-5% solution
Has an unstable shelf life
Pentothal (Specifics)
Splenic Engorgement (not good for abdominal sx)
Contraindicated for hypoproteinemia
Pentothal (Side Effects)
False: Body becomes saturated with drug, revovery prolonged
True or False: Thiopental (Pentothal) is good for TIVA?
Used following Tranquilizer/Alpha 2 agonist
Thiopental (Pentothal) (Use in Horse)
Not Satisfactory- Too much fat
Thiopental /Pentotal (Use in Cattle)
Similar to Dogs and Cats
Thiopental /Pentotal (Use in Pigs)
Ketamine
Tiletamine
Cyclohexamines (Drugs)
Disrupt Nervous System Pathways
Cyclohexamine (Mode of Action)
Sensitive to Sound and Light
Difficult to assess anesthetic depth
Cannot reverse
Tissue irritation
Poor Visceral Analgesia
Ptyalism (Drooling)
Cyclohexamines (Disadvantage)
Significant analgesia to skin and limbs
Helps in speeding recovery
Cyclohexamines (Advantages)
Epileptogenic, Emergence Delirium, Not for repeated administration (TIVA or re-establishing anesthetic depth)
Cyclohexamine contraindications
Apneustic repression which leads to hypercapnia which leads to resp. acidosis
Respiratory effects of Cyclohexamine
Ketaset
Cyclohexamine
Ketamine
Birds, horses and exotics
Ketamine used for induction in
IV
can be given IM or "orally" in fractcious animals
Routes of Ketamine induction
2-6 hours for healthy pt. (approx. 5-10 min of anesthesia)
Duration of Ketamine
Increased salivation
Pain with IM injections
Vocaliazation/Delirium/Seizing during recovery
Not for head trauma pts
Disadvantages of Ketamine (4)
True- Schedule III
True or False Ketamine is a scheduled drug?
eliminate unwanted side effects
produce good skeletal muscle relaxation
Ketamine often used in combo to
Ket/Val (Diazepam/Valium and Ketamin)
Most common Ketamine combo
GKX
Guaifenesin
Xylazine
Large Animal, sometimes cats
Triple Drip
Usually used for induction on?
Tiletamine ( Cyclohexamine) and Zolazepam (Benzodiazepine)
Telazol includes what two drugs?
Schedule III
Is Tiletamine (Telazol) a scheduled drug?
Onset faster
Longer duration of anesthesia
Good Muscle relaxation
good induction agent for cats/dogs
decreased apneustic respiration
good for variety of species (wildlife)
Advantages of Tiletamine (Telazol) (6)
Rough Recovery which is proloned in cats
Disadvantage of Tiletamine (Telazol)
Propoflo, Rapinovet
Cyclohexamine
Propofol Brand name/class
Soybean oil and egg whites which makes it cross the BBB fast because of its lipid solubilty
Propofol is made up of
Will support bacterial growth
Must discard after 6 hours (24 hours ok)
Caution with Propofol why?
Benzyl alcohol added- Lasts 28 days- heinz bodies in cats
Propoflo-28
Short duration (5-10 min)
Does not accumulate (CRI, TIVA, re-establish plane)
No reaction if given perivasculary
Rapid Onset
Good for sight hounds
No need for anticholinergic
Fast, smooth recovery
Safe with hepatic/renal disease
Advantages of Propoflo (8)
Dose-dependant apnea and hypotension
caution if pre-load issue (blood loss/dehydration)
poor analgesia
expensive
poor storage
may exacerbate systemic infections
Disadvantages of Propoflo
High bacteria pt
Spleen sx (past/present) because some drug may be metabolized by spleen
Propofol may be bad for
CNS depression (Unconsciousness)
May produce Resp. Depression/apnea (give slow to px)
Transient decrease in arterial blood pressur and myocardial contractivity
effects of propoflo (3)
IV
Route of Propoflo
Alfaxan
Cyclohexamine
Alfaxalone Brand name/class
Schedule IV
Schedule Alfaxalone?
similar to propoflo but less cardiovascular effects (good for CHF)
Can give IM
Advantages of Alfaxalone
Cost
Rough IM recovery
Controlled Substance
Disadvantages of Alfaxalone
Titrate to effect- Give slowly 0.5-1 ml per 5-10 secs, wait 5-10 sec, repeat
How to administer Propoflo
Amidate
Cyclohexamine
Brand name/Class of Etomidate
Extreme Cardiac Cases
When would we use Etomidate as an induction agent?
May cause pain/irritation with IV infusion
May depress adrenal function for up to 3 hours
May cause retching, apnea, excitement
May cause hemolysis (administer with fluids)
Expensive
Disadvantages of Etomidate? (5)
Rapid onset (15 sec)
Rapid recovery (5 min)
Does not depress cardiopulmonary function (HR, BP)
Rapid hepatic metabolsim
no accumulation
Advantages of Etomidate? (5)
Oxy and Ace
Oxy and Dexdmedetomine
Common Neuroleptanalgesia induction combos (not common but good back up plan)
Induce profound sedation
Usually for high risk puts
May be safe alternative
Advantages of using neuroptanalgesia for induction (3)
Not suitable for routine induction in healthy pts. (wont achieve true anesthesia)
Disadvantage of using neuroptanalgesia for induction (1)
Gecolate aka "GGG"
Muscle Relaxant
Guaifenesin Brand Name/Class
Guaifenesin (Gecolate/GGE) IV
What drug is used for an adjunct to induction in equines?
Good muscle relaxant that does not affect the diaphragm or resp. center
Advantages of Guaifenesin (Gecolate/GGE)
may cause transient hypotension
only use 5% (>10% irritant to body tissues and can cause hemolysis)
must administer under high pressure (large amounts)
Disadvantages of Guaifenesin (Gecolate/GGE) (3)
5% dextrose, 5% Guaifenesin (Gecolate/GGE)
5 & 5
Technique of administering anesthetic agents via the lungs
Inhalation Anesthesia
Liquid anesthetic vaporized into O2
Delivered to pt. by mask or ET tube
Conducted to air passages and into alveoli
Anesthetic diffuses across resp. membrane into blood stream
Inhalation Anesthesia intake into the body (4 steps)
concentration gradient b/w alveoli and blood
tissue perfusion
Inhalation Anesthesia- Rate of diffusion is controlled by
% anesthetic delivered
ventilation of pt
Depth of anesthesia maintained through
to create steep gradient for removal of anesthetic gas
why is it important to leave pt on 100% O2 for 5 min
the amount of liquid anesthetic that will evaporate at 20 degrees C and determines the type of vaporizer required
Vapor pressure
False- High vapor pressure evaporate readily and reach lethal concentration of 30% in O2
T/F agents with a high vapor pressure will not evaporate and is safe to leave out
To limit Vaporization to 5% (less fatal of a dose)
Why do high vapor pressure anesthetic require precision vaporizer?
High vapor pressue
High/Low vapor pressure requires precision vaporizer?
Halothane: 244 mmHg
Isoflurane: 241 mmHg
Sevoflurane: 160 mmHg
Methoxuflurane: 22.5 mmHg
Specific Vapor Pressures:
Halothane:
Isoflurane:
Sevoflurane:
Methoxuflurane:
Low vapor pressure
Low/High vapor pressure can safely be used in a nonprecision vaporizer?
Anesthetics tend to remain as a gas in the alveoli (rapid induction, depth change, recovery)
Low solubility coefficient
Halothane- 2.4%
Isoflurane- 1.2%
Sevoflurane- O.6%
(works faster)
Low soluble anesthetic gases (Spec #'s)
Anesthetics dissolve readily in blood and tissue (changes back to liquid). Slow induction, depth change, revovery
High solubility coefficient
Low solubility- Anesthetics tend to remain as a gas in the alveoli (rapid induction, depth change, recovery)
Which solubility coefficient better with anesthetic gases?
Methoxuflurane- 12%
High solubility anesthetic gas
The lowest concentration which produces no response to pain in 50% of pts exposed to painful stimuli (potency of drug- effective dose for analgesia)
Minimum alveolar concentration (MAC)
Less potent/Less pain relief
higher MAC=
More potent/more pain relief
lower MAC=
Sevo- 2.4% MAC
Iso- 1.2-1.3% MAC
Halothane- 0.87% MAC
Methoxyflurane- 0.23% MAC
Highest to lowest MAC therefore Least to most potent/pain relief
Fluothane
Inhalant anesthetic
Red tank
Halothane
Halothane (Fluothane)
What inhalant anesthetic is better for equines because it always for cognitive and motor function to return at the same time?
red
Halothane (Fluothane) tank color
Sensitizes heart to catecholamines (VPC's- Bradycardia)
Associated with malignant hyperthermia
resp. depressant- decreases tidal volume (dose dependent)
Disadvantages to Halothane (Fluothane) (3)
Not for pt. with liver problems
or cardiac conditions
Contraindications of Halothane (Fluothane)
Aerrane, Isoflo, Forane
Inhalant anesthetic
Purple tank
Isoflurane
Ultane, Sevoflo
Inhalant anesthetic
Yellow tank
Sevoflurane
Iso- 1.4%
Sevo- 0.6% (twice as fast onset/recovery)
Solubility coefficient Iso and Sevo
Sevo- 2.4%
Least potent/Highest MAC
2.5% for 15 min
1.5% maintanance
Induction/Maintanance dose for Iso and Halothane
4.5% induction
3.5% maintance
induction/Maintanance dose for Sevo
Cardiac pt
Hepatic pt
Renal pt
Neonates
(most of drug is eliminated by lungs)
Sevo/Iso inhalation drug of choice for (4)
Rapid induction/recovery/change in depth
Low rubber solubility
few adverse reactions
advantages of sevo/iso (3)
High MAC/ Low potency
Vasodilation
disadvantages of sevo/iso
cognitive and motor skills return at the same time
advantage of sevo over iso
50-80%
Halothane elimination via respirations
20-50%
Halothane metabolization via liver/kidney
99%
Isoflurane elimination via respirations
1%
Isoflurane metabolization via liver/kidney
3%
Sevo metabolization via liver/kidney
97%
Sevo elimination via respirations
Hypotension (vasodilators)
All inhalant gases cause
taking an animal from the normal conscious state and rendering unconscious (most vulnerable time of anesthesia)
Induction Period
Induction Period
Most vulnerable time of anesthesia
Injectable and inhalant
2 types of induction agents
extremely slow, titrate to effect
How to give injectable induction
unconsciousness, relaxed jaw tone
two things you look for induction period?
False- Never use inhalation agents on brachycephalic due to redunant sort palate
True/False The best way to induce a Brachycephalic is through inhalation anasthetics?
set high oxygen flow rate (2-5 L 02/min)
Set high vaporizing setting (ISO- 4-5%, Sevo 6-8%)
Ad) Faster induction than nice way
Dis) Vasodilation (hypotension), patient cooperation, waste gas
Blast em technique
Advantages?
Disadvantages?
Set high O2 flow rate (2-5 L O2/min)
100% O2 1min
increase vap 0.5% every min
Ad: Less pt anxiety= less catecholamine production
Dis: Longer induction process, Knowing when to intubate
Nice way tech
Advantages, Disadvantages?
Murphy eye tube*
Cole
2 types of ET tubes
Provide patent airway
Prevent aspiration
Provide efficient delivery
Decrease physiologic dead space
Allow for controlled vent. of pt
Reasons for intubating? (5)
Inflammation/Irritation of mucosa of trachea
Development of mucous plug and obstruction of tube
stimulation of vagas nerve
Risk of bronchii insertion
Can contribute to hypothermia
Disadvantages of ET tube use (5)
*Poor pt positioning
Laryngospasms
Inadequate plane of anesthesia
3 cause for difficult intubation
Period of time following anesthetic induction in which a stable level of anasthesia is achieved.
Maintenance period of anesthesia
Slight increase in heart rate and RR due to surgical stimulation
describe "stable" anesthesia
Stage 1- Voluntary excitement phase
-conscious
- +/- decrease pain sensitivity
-HR/RR normal
-+/- disoriented
Describes?
-conscious
- +/- decrease pain sensitivity
-HR/RR normal
-+/- disoriented
Stage 1- Voluntary excitement phase
Stage II- Involuntary excitement phase
Induction phase is what stage/plane of anesthesia?
Stage III Plane I
Light Anesthetic plane
In what Stage/Plane to we intubate?
Stage III/Plane II
What stage/plane is best for sx?
Stage III/ Plane II
-Slight decrease of HR/RR until surgical stimulation then increases
-most protective reflexes are absent
Describes what stage/plane?
-Slight decrease of HR/RR until surgical stimulation then increases
-most protective reflexes are absent
Stage III/ Plane II
Stage III/Plane III
Deep anesthetic plane
-HR/RR depressed
- no response to sx stimulation
- all reflexes absent (jaw tone slack)
- requires extreme monitoring
Describes what stage/plane?
-HR/RR depressed
- no response to sx stimulation
- all reflexes absent (jaw tone slack)
- requires extreme monitoring
Stage III/Plane III
Deep anesthetic plane
Stage III/Plane IV
Overdose of Anesthetic
-+/- HR decreased or increased
- RR very depressed
-Hypotension
-no reflexes
Describes what stage/plane?
-+/- HR decreased or increased
- RR very depressed
-Hypotension
-no reflexes
Stage III/Plane IV
Overdose of Anesthetic
Stage IV
Coma/Death
Describes what stage/plane?
Coma/Death
Stage IV
Palpebral/"Blink"
*Jaw tone
Pedal Reflex/Toe Pinch
Eye Rotation
Ear Flick Response
Swallowing/Gag reflex
Nystagmus
Reflexes to check if deep enough?
Cats and horses
Ear Flick Response can be used on
medial and ventral (cross eyed)
if central= too light or deep
During surgical plane of anesthesia eye rotate
Individual variation
Ventilating pt. too frequently
improper vaporizer function
tech errors
4 Reasons pt may be getting to deep?
individual variation
inappropriate O2 flow rate (low)
Is there any gas in vaporizer?
Leak in system?
ET tube improperly placed
Over usage of O2 flush valve
7 Reasons pt may be getting to light
Blood pressure
Most overlooked parameter in monitoring anesthesia?
Force of luminal pressure against wall of vessel
Blood pressure definition
100-160 mmHg
Systolic BP normal
60-100 mmHg
Normal Diastolic BP
80-120 mmHg
Normal Mean BP
20 less than minimum of each
S- < 80mmHg
D- < 40 mmHg
M- < 60 mmHg
Hypotensive values for Systolic, Diastolic, Mean BP
C.O
Vascular resistance
Blood volume
3 things that contribute to BP
*OD of anesthetic gases (99% of time)
Hypovolemia
Decrease C.O (Bradycardia, Dysrhythmia, Pt. positioning)
...
-+/- decrease of anesthetic gases
- IV bolus of fluids (add 20ml/kg/hr)
- Positive inotropic drugs (Ephedrine sulfate, CRI of Dopamine)
3 ways to manage hypotension
Cuff (40% circumference of leg, attached to sphygmomanometer, proximal to crystal)
Crystal (placed concave on artery, taped in place)
Placement of Doppler
add 15 mmHg for mean
artificial low systolic
Doppler on cats you need to
-Amount of Hemoglobin saturated with Oxygen (SpO2)
-Pulse Rate
Pulse Oximeter used to read
Non-pigmented skin
-Tongue
-Pinna
-Toe webbing
-Vulva/Prepuce
-Rectal Probe
(light through artery first, keep moist)
Where do you place a pulse oximeter?
-V/Q mismatch (decrease in transmission of gases across alveolar sacs/longer distance (fluids) b/w alveoli and capillaries)
-Disconnect from breathing system
-Blocked airway
-Inadequate O2 flow rate
* Erroneous readings
-Probe placement issues
- Hypovolemia
6 reasons for SpO2 desaturation
D- 60-160 bpm
C- 110-220 bpm
H- 30-40 bpm
Pulse rate normals
Dog, Cat, Horse
Awake= >90%
Anesthetized= >95%
SpO2 Normals
decreased TV of about 25%
tidal volume while on general anesthesia?
Prevent Hypercapnia
Prevent Atelectasis
Two main reasons why we Ventilate?
*Capnograph
*Reservoir Bag
-Other devices (Esophageal stethoscope, Flutter valve)
-Rate/Character
4 ways to monitor RR
RR
ETCO2- End Tidal Co2
InCO2- Inspiratory CO2
3 values from capnograph
35-45 mmHg
Normal ETCO2 rate under anesthesia
Cat/Dog- 8-20 rpm
Horse- 8-12 rpm
Normal RR under anesthesia (Cat, Dog, Horse)
0-5 mmHg
Normal InCO2 under anesthesia
Resp. acidosis
ETCO2 > 45mmHg
Resp. Alkalosis
ETCO2 < 35mmHg
1) close pop-off valve
2) Squeeze 20cm of H20
3) Open pop-off valve
3 steps to ventilating
-Px Atelectasis
-Px Hypercapnia
-counteract hypoventilation
-Increase Tidal Volume
-Px hypoxia
-Some sx require (thoracic, long, GDV, Colic)
6 reasons why we ventilate
-Ventilate at rate of 12-16 rpm
- After appox. 3-5 min. watch pt (notice when breathing stops)
- Decrease ventilation to 8-12 rpm rest of sx
-Recovery= decrease ventilations at rate of 1 res. every 2-3 min.
Process of completely taking over respirations with reservoir bag
-Inspiratory pressure
-Inspiratory time (I:E)
-Tidal Volume
-Resp. Rate
Mechanical Ventilators can control 4 things
Bird Mark 7
Pressure Cycle Ventilator common name
Pressure cycle Ventilator (Bird Mark 7)
Air may leak- never reaches pressure- over inflate chest
Least safe ventilator and why?
Volume Cycle Ventilator/Ohio Metomatic
Most safe Mech. Vent.
Inspiratory pressure
Pressure cycle/Bird Mark 7 ventilator must set...
Tidal Volume
Volume Cycle Ventilator/Ohio Metomatic must set...
Ohio Metomatic
Volume Cycle Ventilator common name
Drager
Time Cycle Ventilator common name
Inspiratory time
Better to control CO2 levels
Time Cycle Ventilator/Drager must set?
advantage?
hypotension
over ventilating may lead to
Heart Rate
Heart Rhythm
2 values ECG gives
Cautery, Movement, Electric Dental Equipment, Drying out of electrodes, 60 cycle interference
5 most common types of artifacts on an ECG
-Electrolyte imbalance (hypokalemia, hypomagnesemia)
-GDV
-Catecholemines (Epinephrine)
-Drugs (Barbiturates)
4 Generalized causes of VPCs
-Find underlying cause
- increase ventilations (more O2 to heart)
- Notify Dr.
-Lidocaine/Procainamide to slow down HR
Tx for if needed
V-Tach
VPC
V-Tach
Lidocaine (CRI)
Procainamide (Pronestyl)
Tx
V-Fib
Defibillation
CPR
Tx
Sinus Tachycardia
Increase O2 flow rate, Increase anesthetic
>160 bpm
Tx
Sinus Bradycardia
+/- decrease anesthesia
Anticholinergics (Atropine)
<40 bpm
True
True/False 1 and 2 degree AV blocks can be normal in equines
1 degree AV block
2 degree AV block
Tx: Atropine
Tx:
3rd degree AV block
Tx: Pacemaker
Tx:
25%
T-waves should be no more than ____% the height of R-wave
Myocardia Hypoxia
Tx: Ventilate
Broadened and Heightened T-wave indicates
Tx:
Electrolyte Imbalance
(beware VPC's are coming)
Common in Blocked Toms
Tx: Dextrose
Spiked T-waves indicate
Common in?
Tx?
lead to?
A genetic disorder will have increased muscle activity leading to hyperthermia (under anesthesia)
Malignant Hyperthermia
-Decreased muscle activity
- Decreased metabolic rate
- introduction of cold gases
- Sx. prep (shave, alcohol)
- Opening of body cavities
Hypothermia causes (in anesthesia) (5)
-Keep something b/w pt and table (blankets, circulating water blanket)
-Warm IV Fluids
-Warmies
-Bear hugger
4 ways to px hypothermia
no physiologic consequences
> or equal to 96 F
90-94 F
at what temp do we have body system depression
82-86 F
at what temp do we have complete body system depression aka coma?
Class I
What would the anesthetic risk be for a normal healthy patient undergoing an elective procedure? (excellent anesthetic risk)
Class II
What would the anesthetic risk be for a patient with a slight to mild systemic disease with no functional limitations, a well-controlled disease of one body system? Possibly mild to moderate obesity. (good anesthetic risk)
Class III
What would the anesthetic risk be for a patient with a moderate systemic disease that limits activity but not incapacitating, mild clinical signs. (fair anesthetic risk)
Class IV
What would the anesthetic risk be for a patient with a severe systemic disease that is a constant threat to life, has at least one severe disease that is poorly controlled. (poor anesthetic risk)
Class V
What would the anesthetic risk be for a patient that is moribund and not expected to survive 24 hours with or without surgery, this would be a last ditch effort. (guarded anesthetic risk)
The absence of pain perception
Define Analgesia
Pain assessment
What is the 4th vital sign?
Hyper excitability of central neurons due to the constant bombardment of pain signals, this creates an increased sensitization to pain
Define wind-up
1. Wind-up
2. Amount of GA
What two things do Pre-emptive analgesics decrease?
Pain cause by a stimulus that normally does not result in pain
Define Allodynia
Increased response to a painful stimulus
Define Hyperalgesia
1. Allodynia
2. Hyperalgesia
What two things does Wind-up lead to?
1. Opioids
2. NSAIDs
3. Local anesthetics
Name three common analgesics
The pain receptors in the brain and spinal cord
What do opioids act on?
Anxiety and vocalization
What might a dysphoric patient experience?
Yes, some
Will opioids produce sedation?
1. Morphine
2. Hydromorphone
3. Fentanyl
Give three examples of Opioids
Oral transmucosal
What does OTM stand for?
Cats
What species is the administration of a drug via OTM most effective in?
1. PO
2. IM/SQ
3. Transdermal
4. Intraarticular
Give 4 routes of administration of an opioid
1. Analgesia
2. Anti-inflammatory
3. Antipyretic
What are the three properties of NSAIDs?
1. Somatic (musculoskeletal)
2. Visceral (organs and soft tissue)
Where do NSAIDs provide analgesia?
Prostaglandins, by inhibiting enzymes COX 1 and 2
What do NSAIDs cause inhibition of?
The production of good prostaglandins. They maintain renal blood flow, produce gastric mucus and maintain platelet function.
What are COX 1 enzymes important for?
The production if prostaglandins that cause pain and inflammation.
What are COX 2 enzymes important for?
1. Carprofen
2. Meloxicam
3. Deracoxib
Give three examples of NSAIDs
1. PO
2. Injectable
What are the two routes of administration of NSAIDs?
24 hours
How long does the analgesic properties of one injection of Carprofen last?
1. Gastric ulcers
2. Renal toxicity
3. Impaired platelet function
4. Hepatic damage
What are 4 possible NSAID side effects?
-caine
What is the suffix associated with local anesthetics?
By blocking the sensory nerve impulses and transmission of pain impulses, temporary loss of sensation
How do local anesthetics work?
Balanced anesthesia
What is it called when a local anesthetic is used with GA?
1. Lidocaine for cat intubation
2. "Splash Block"
Name two topical uses of a local anesthetic
Lidocaine
What local anesthetic are cats sensitive to?
1. Incisional block
2. Onychectomy (ring block)
Name two infiltrative uses of a local anesthetic
Targets a specific nerve
What does a direct nerve block do pertaining to a local anesthetic?
1. Topical
2. Intraarticular
3. Epidural
Give three routes of administration of a local anesthetic
Morphine, Lidocaine, Ketamine
What does MLK stand for?
Lidocaine
What is the most common local anesthetic to add as a CRI?
1. Lidocaine
2. Bupivacaine
3. Mepivacaine
Give three examples of a local anesthetic
Epinephrine
What is common to add to a local anesthetic to increase the duration of the anesthetic?
It causes vasoconstriction so the local anesthetic isn't absorbed into the bloodstream, this can increase the duration by 50%
Why does the addition of epinephrine increase the duration of a local anesthetic?
IV, it is cardiotoxic
Which route should bupivacaine never go and why?
Sedatives
What are Alpha-2 Agonists?
Pain receptors in the brain and spinal cord
What do Alpha-2 Agonists act on?
Okay in the young and healthy, avoid in the old and sick
What is the general rule of thumb when using Alpha-2 Agonists?
Sedation
What lasts longer with Alpha-2 Agonists, sedation or analgesia?
1. Xylazine
2. Medetomidine
3. Dexmedetomidine
Give three examples of Alpha-2 Agonists
Alpha-2 Antagonists
What are Alpha-2 Agonists reversed with?
NMDA receptor
What receptor does Ketamine work on?
1. Acupuncture
2. Massage
3. Chiropractic
Give three examples of non-pharmacological methods of pain control
Anxiety and fear
What two things can amplify pain?
opioid + sedative/tranquilizer
What is a neuroleptanalgesic?
Robinul-V
Brand name for Glycopyrrolate
Calm, decrease stress and anxiety, muscle relaxation, decrease motor activity, aid in restraint prevent bradycardia and dry secretions
Why do we use PA drugs?
15-30 minutes
How long before induction are PA's given?
1. Anticholinergics
2. Tranquilizers
3. Alpha-2 agonists
4. Opioids
5. Neuroleptanalgesics
What are the 5 PA drug classifications?
1. Atropine
2. Glycopyrrolate
What are the two anticholinergics we commonly use?
Destruction/breakdown of parasympathetic system
Define parasympatholytic
1. Sympathetic (adrenergic)
2. Parasympathetic (cholinergic)
What are the two branches of the autonomic nervous system?
Bradycardia
What does vagal stimulation cause?
Acetylcholine
What do anticholinergics block the function of?
Salivary, decrease salivary and respiratory secretions, can cause a mucus plug in cats, however
"S" in Slured heart
Lacrimal, decreases lacrimal secretions
"L" in Slured heart
Urinary, contractions of the ureters and bladder are reduced
"U" in Slured heart
Respiratory, causes bronchodilation and decreases respiratory secretions
"R" in Slured heart
Eyes, causes mydriasis and decreased PLR
"E" in Slured heart
Digestive, decreases GI motility, contraindicated for horses (colic)
"D" in Slured heart
Heart, blocks the stimulation of the vagus nerve, prevents bradycardia. The main reason to use an anticholinergic is to prevent bradycardia
"<3" in Slured heart
Lidocaine
What drug can you give to a horse via CRI to increase gut motility to prevent colic?
60-90 minutes
What is the duration of Atropine?
A dose dependent/transient 2 degree AV block
What can atropine cause concerning the heart?
4 hours
What is the duration of Glycopyrrolate?
Glycopyrrolate
Which anticholinergic is typically used for longer procedures?
1. Pre-existing tachycardia
2. Ileus
3. CHF/ Hyperthyroidism
4. Mucus plugs in cats
What are the 4 contraindications of anticholinergics?
1. Phenothiazines
2. Benzodiazepines
What are the two groups of tranquilizers?
To decrease induction drug administration, allow for a smoother induction phase and to decrease the amount of post op drugs
Why do we give PA drugs?
Acepromazine and acetylpromazine
List two Phenothiazines commonly used
Diazepam, Midazolam and Zolazepam
List three Benzodiazepines
4-8 hours, up to 24
How long does Promace typically last?
1. Antiemetic
2. Antiarrhythmic
3. Antihistamine
What are three properties of acepromazine?
No, it is an antihistamine so it will block any allergic response
Can Ace be used in animals undergoing allergy testing? Why?
hypotension and hypothermia
What can the vasodilating effects of phenothiazines result in?
Acepromazine
Which drug causes prolapse of the third eyelid and a penile prolapse in horses?
It will effect the function of platelets and a drop in PCV due to an increase in splenic uptake of RBCs
What are two effects of phenothiazines relating to the blood?
Boxers, labs and herding breeds
What are a few dog breeds that seem to be hit hard with Ace?
3mg
What is the maximum dose of acepromazine?
No
Is acepromazine reversible?
Doxapram
What drug is a respiratory stimulant and also a CNS stimulant?
Flumazenil
What is the reversal agent for the Benzodiazepine group?
Ketamine
What is the only drug that mixes well with Diazepam?
Yes
Are benzodiazepines controlled substances?
Anti anxiety, calming and anticonvulsant
What are the effects of benzos?
The old and debilitated
What age of animals do benzos work best on by itself?
Excitement instead of calming
What is a possibility when using benzos by themselves in the young and healthy patients?
Because ketamine causes catalepsy, benzos are good muscle relaxers
Why is it common to use a benzo in conjunction with ketamine?
High
Do benzos have a high or low margin of safety?
Slow, fast administration can cause venous thrombosis, phlebitis and bradycardia
Should Diazepam be given slow or fast? Why?
A couple of hours
How long do benzos last?
Zolazepam
What benzo can be used as a sole anesthetic agent for short and minimally painful procedures?
Xylazine, Medetomidine and Dexmedetomidine
List three alpha-2 agonists
Atipamezole (Antisedan)
What is the reversal for Alpha-2 agonists?
No
Are Alpha-2 agonists controlled substances?
1. Sedation
2. Analgesia
3. muscle relaxation
What are the effects of Alpha-2 agonists?
A couple of hours
How long do alpha-2 sedatives usually last?
Sedation
What lasts longer in alpha-2 agonists, sedation of analgesia?
Emetics
Are alpha-2 agonists emetics or antiemetics?
If they are highly agitated, they can override the drug and show signs of excitement/aggression
Why should the animal be fairly calm before receiving an alpha-2 agonist?
Peripheral vasoconstriction and decrease tissue perfusion
What are two general side effects of alpha-2 agonists?
ADH
What do alpha-2 agonists interfere with the release of concerning the urinary system?
Yohimbine
What is the reversal for Xylanzine?
Okay in the young and healthy, avoid in the old and sick
What is a general rule of thumb concerning alpha-2 agonists?
In mcg/sq meter of body surface
How is Medetomindine dosed?
Before the alpha-2 agonist
When should an anticholinergic be given if being combined with an alpha-2 agonist?
IM
What is the only route of administration that Antisedan can be given?
Opioids
What are the most effective agents for the treatment of pain?
Yes
Are opioids controlled substances?
Opioids
What is the safest drug group in the old and sick?
Mu, Kappa, and Sigma
What are the three receptors that opioids act on?
Morphine, hydromorphone, and fentanyl
List three full mu agonists
Mixed agonist/antagonist
What kind of opioid is Butorphanol?
Partial mu agonist
What kind of opioid is Buprenorphine?
Naloxone
What is the reversal for opioids?
Opioids
What group of drugs can narcosis be seen in?
Respiratory depression
What is the most common side effect of opioids?
Emetics
Are opioids emetics or antiemetics?
Duramorph
What is the preservative free brand name for morphine?
4-12 up to 24
How long do opioids last?
5 times
How much more potent is hydromorphone than morphine?
Less
Is hydromorphone more or less likely to cause vomiting?
10 times
How much more potent is oxymorphone than morphine?
100-150 times
How much more potent is fentanyl than morphine?
As a CRI or transdermal patch
Since fentanyl has a short duration, how is it most commonly used?
3-5 days
How long do the analgesic properties of the fentanyl patch last?
Recuvyra
Name the fentanyl transdermal solution applied to the skin
No, only mild to moderate
Is Butorphanol effective to use for severe pain?
Butorphanol
What other opioid can partially reverse full mu agonists?
6-8-12 hours
How long does Buprenorphine last?
Simbadol
What is the SQ version of Buprenorphine only approved in cats that lasts 24 hours?
Titrate to effect
What can you do to Naloxone to reverse the respiratory depression or dysphoria without reversing the analgesic properties?
Re-Breathing: 30mls/kg/min
Non Re-Breathing: 200mls/kg/min
Oxygen Flow Rate
psi x 0.3= L
Liters of Oxygen in tank
L of O2 in tank
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O2 Flow Rate
Time Remaining in Tank
10-15 mls/kg
Tidal Volume
60mls/kg = L (round up)
Reservoir Bag Size