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429 Cards in this Set

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What are the 2 recognized non-animal risks in vet hosp?
Radiation
Trace Anesthetic Gases
What are 6 less recognized non-animal risks in vet hosp?
Hazardous chemical spills
Fire
Tornado
Earthquake
Flood
Robbery
Businesses with ____ employees musthave emergency plans documented in writing to deal with events. What do businesses with less than ___ need to have?
11+
Need to have a plan but don't need to be documented
*EACH EMPLOYEE MUST UNDERSTAND THE PLAN AND KNOW HIS ROLE*
The potential risk assoc with anesthetic gases has been recognized since ____ by what society?
1974
The American Society of Anesthesiologists
Name 7 health problems associated with repeated exposure to anesthetic gases.
Spontaneous abortion rate
Congenital abnormalities found in offspring of women
Congenital abnormailities found in offspring of men
Cancer rate in women
Hepatic disease in women
Renal disease in women
Cognitive skills are decreased
Unscavenged levels in vet operating rooms averaged _____ compared to ____ when scavenged.
4.7ppm
1.4ppm
How long are anesthetic metabolites (halothane) found in patients?
20 days
How long is N2O exhaled for?
56 hours
How long are traces of gases (halothane) found in the urine of anesthesiologists?
64 hours
Has there ever been a study done that conclusively links trace levels of inhalent anesthetics to any disease?
NO but because of links, OSHA created standards and recommendation for dealing with anesthetic gases.
What is the purpose of scavnaging equipment?
Collect the excess anesthetic gases and remove them from the operating room environment.
How are gases removed via a scavenging system?
Exhausting them to the outdoors via passive system
Exhausting them outdoors via active system (suction)
Absorption with activated charcoal
Do you need to scavenge isoflurane out of the operating room even though it is minimally metabolized?
YES
What is the largest source of anesthetic gases leaking into room?
Pop-off valve
What are 4 routine maintenance procedures you need to do for your anesthetia equipment?
Routine cleaning
Daily checks for leaks
Frequent calibration (4 months?)
Records of all maint checks
After disconnection from anesthetic machine, where should the animal be placed?
Well ventilated area for recovery
What are 4 ways to minimize gas use?
Use low fresh flow rates (10ml/kg/min)
Use nonbreathing systems only on animals <2-3 kgs
Reduce the use of masks and induction chambers (dumps anesthetic gas into room when take off lid)
Eliminate use of N20 (needs higher gas flow rates)
What should your anes. levels be for potent nesthetics?
<2ppm
What should your anes levels be for N20?
<25 ppm
What are 4 common sources of leaks of anes gases?
Uncuffed ET tubes
Holes in rebreathing bags
The pressure relief valve (pop-off valve)
Spilled liquids
What are 3 things that are your responsibility as a vet to ensure safety of employees regarding risks in vet clinic?
ID potential hazards
Develop an action plan to deal with the hazard
Communicate the plan to all empoyees
Give an example of secondary labeling.
Buy alcohol by the gallon and pour it into smaller bottles for use - these smaller bottles must be labeled.
When do you need to label common chemicals (ie bleach)?
When it is used in a manner that is outside its normal use (for disinfection)
When do you need to label bleach - for laundry or for disinfection?
DISINFECTION
Health care professionals who abuse substances generally use more than ___ substances.
4
What is usually required to recover from overdose of xylazine?
Ventilation
What should you give to someone that ODed on detomidine and butorphanol?
IV fluids and naloxone
What is the maximum concentration of isoflurane at room temp?
33%
1ml of isoflurane liquid becomes ____ml of isoflurane vapor?
200ml
What is the open drop method of anes delivery?
Patient is enclosed in a chamber to which anesthetic is added; great with agents of low vapor pressure (ie methoxyflurane)
What type of drug is great in an open drop method of anes delivery?
Agents of low vapor pressure (ie methoxyflurane)
What is the modified open drop method of anes delivery?
Anesthetic machine is used to deliver a specific controlled flow and concentration of anesthetic and oxygen.
What device regulates the agent concentration in the modified open drop method?
Vaporizor
In what type of anes delivery method is agent concentration not monitored?
Open drop method
What is the modified open system of anes delivery?
Oxygen and anes vapor is delivered to patient via "primitive" circuit; difficult to control oxygen and anes concentration; dilution with room air; when animal inhales they may inhale some expired gas along with fresh air
Is it easy to give an animal a breath of fresh air in an open system?
NO - difficult because when animal inhales they may inhale some expired gas (along with fresh gas)
What is a semi-open system?
A resevoir is added to minimize dlution with air; patient gets 100% fresh gas with every inhalation
What is another name of modern semi-open system?
Non-rebreathing
What are the 2 functions of the anesthetic machine function?
Deliver oxygen and volatile anesthetic to resp system
Remove CO2 from resp system
What 2 components make up the high pressure system?
O2 and N2O cylinders
Pressure regulators
What color is the O2 cylinder in the US?
Green
What color is the O2 cylinder in any other country besides US?
White
What color is the N20 cylinder?
Blue
WHat is the pressure of a full O2 cylinder?
2200 PSI
What is the pressure of an N20 cylinder?
750 PSI
Does the pressure inside the O2 cylinder drop as you use the gas and why?
Yes - O2 stored in cylinder as gas
Does the pressure inside the N20 cylinder drop as you use the gas and why?
No - N2O stored as liquid; only drops when all liquid is gone
What do pressure regulators do?
Adjust the variable tank pressure to a constant pressure (50-60psi)
What are the 5 components of a low pressure system?
Flowmeters
O2 flush valve
Vaporizer
Oxygen failsafe
Common gas inlet and outlet
What isthe anesthetic vaporizer?
Can be adjusted to deliver a specific gas concentration (%)
What 3 things determine how the anesthetic vaporizor functions?
Anesthetic agent (agent specific)
Temp compensated
Flow compensated
If temp increases in the vaporizor, then the vaporization will (inc/dec)
Increase
What is the anesthetic breathing circuit?
Connects the fresh gas outlet to the patient to the anesthetic machine
What are the 2 commonly used breathing circuits in vet med?
Circle rebreathing (most commonly used)
Non-rebreathing
How does the circle rebreathing system work?
Exhaled gas is cleansed of CO2 and the remaining gas is rebreathed.
What does the amount rebreathed depend on in the circle rebreathing system?
Fresh gas flow rate
What is the minimum flow equal to in the circle rebreathing system?
Minute oxygen consumption (VO2) - 3-5 ml/kg/min
What happens if you set the flow rate higher in the circle rebreathing system?
The extra O2 goes out the pop-off valve
What is is the % inhaled O2 and the % exhaled O2 in the circle rebreathing system?
21% O2 inhaled
16% 02 exhaled
What do flowmeters do?
Regulate the flow rate (liters/min) of the O2 and N2O that enters the vaporizer and is delivered to the breathing circuit.
Is the flow meter for the O2 and N2O separate or the same?
Separate
What do one way (unidirectional) valves do?
Maintain a one way flow of gas withn the circuit; minimizes dead space (therefore the dog does not breath in its previously exhaled gas)
What do the pressure relief (pop-off) valves do?
Remove excess gas from the system (any gas flow rate >VO2)
At what level of VO2 will the pop-off valves remove the gas?
>VO2
Where does the waste gas go after leaving the pop-off valve?
Scavenging system
What should you do to the pop-off valve when squeezing rebreathing bag for assisted ventilation?
Close the pop-off valve
What is the passive system waste scavenging system?
Waste flows passively from the pop off valve through charcoal canister or out of the room
What is hte vacuum interface waste scavenging system?
Waste gas is actively removed via vacuum
What is the purpose of the reservoir (rebreating) bag?
Allows inhaled and exhaled gas to move into and out of the system; aids in monitoring RR and aids in delivering an assisted breath
What are 2 things the reservoir (rebreathing) bag helps with?
Monitor RR
Deliver an assisted breath
What should the size of the rebreathing bag be?
3-5X Vt
How does the CO2 absorber canister produce carbonate?
Reacts with water and CO2 to produce carbonate
Is the CO2 canister exothermic or endothermic?
Exothermic (feels hot)
What color is the CO2 canister limestone before and after it is used up?
White before
Purple after
What does the pressure gague tell you?
How hard to squeeze the bag to deliver a breath (15-20 cm H2O)
What does the Y-piece do?
Connects 2 breathing hoses to ET tube/mask
What type of patients use a non-rebreathing circuit?
Small patients (<5kg)
How does a non-rebreathing circuit work?
Gas flows from vaporizer and common gas outlet to the ET tube
FGF pushes the exhaled CO2 away from patient end of the circuit
Does the patient inspire CO2 in the non-rebreathing circuit and why?
NO
FGF pushes exhaled CO2 away from patient end of circuit
What is FGF?
Fresh Gas Flow
How high is the FGF in the non-rebreathing system?
High (>150 ml/kg/min)
What are the 2 advantages of a high FGF in a non-rebreathing circuit?
Dead space is minimized
Resistance to breathing is minimized
What are 2 disadvantages of a high FGF in a non-rebreathing system?
Expensive
Patient continually breaths cold, dry gas
What does Doppler measure (2)?
HR
BP
What does the capnometry measure (2)?
RR
EtCO2 (end tidal)
What does pulse ox measure (2)?
HP
SpO2
What does mechanical ventilation do to preload, minute volume, BP, and afterload?
Decreases preload
Increases minute volume
Decreases BP
Increases afterload
Does mechanial ventilation increase PaCO2?
NO
What is the single most important aspect of anesthesia?
Monitoring
What 4 things are most important to monitor during anesthetia?
Depth of anesthesia
CV status
Resp status
Oxygenation
What are the 6 ACVA Monitoring Guidelines?
Ensure bl flow to tissues in adequate
Ensre adequate oxygen concentration in the patient's arterial blood
Ensure the patient's ventilation is adequately maintained
Record monitored variables at regular (q 10 min) intervals
Maintain a legal record of significant events
Ensure a responsible individuall is aware the patient's status at all time during anesthesia and recovery
Is depth of anesthesia rountinely recorded?
NO
What 3 things is anesthetic depth based upon?
Somatic muscle tone
Respiratory patterns
Ocular signs
What is stage I?
Analgesia
What is stage II?
Delirium
What is stage III?
Surgical (Planes 1-4)
What is stage IV?
Resp Paralysis
What CNS changes (5) do you see with anesthetic depth?
Movement in response to surgery
Eye reflexes (palpebral reflexes)
Position of eye in orbit
Pedal reflexes
Anal tone
(EEG (research))
What muscle do you look for relaxation when monitoring anesthetic depth?
Jaw tone
What is the MAC for surgery?
1.5
Is eyeball position (in monitoring anes depth) more useful in large or small animal?
Large animal
Where will the eye be rotated if in a light anes plane?
Ventromedial or dorsolateral
Where will the eye be rotated if in moderate anes plane?
Slightly ventral but centrally positioned
Where will the eye be rotated if in deep anes plane?
Central with dolated pupil
How loose should the jaw be if the patient is just right (out of 10)?
5-7/10
What if the patient has a fast HR and high BP under anesthesia?
Too light
What is the patient has a fast HR and low BP under anes?
Moderate anes
What if the patient has a slow HR and low BP under anes?
Deep anes
What is the animal is breathing fast and deep?
Too light
What if the animal is breathing fast and shallow?
Too deep
What if the animal stopped breathing?
Too deep
What if animal is breathing slowing and deep?
Just right
What are the best 2 ways to monitor CV during anes?
HR
BP
Name 4 ways to masure HR during anes
Palpatin of pulse
Auscultate heart sounds - esophageal stethoscope
ECG (measures electrical deflections from baseline)
Pulse Ox (counts pulses)
How do you measure BP during anes?
Indirect - Doppler, Oscillometric
Direct - Pressure transducer coupled with an arterial catheter
What is Doppler BP used for in exotics?
Monitor HR
Does Doppler report systolic or diastolic values?
Systolic
What is the best way to track BP trends?
Doppler (or oscillometric)
Name 3 limitations of Oscillometric BP monitors.
Smaller patients
Motion
Lower pressures
What 4 values does the oscillometric BP monitors display?
HR
Systolic BP
Diastolic BP
Mean BP
What precent of the limb/tail circumference should the BP cuff be?
40-50%
What value is hypotension?
Mean BP <60 mmHg
What 6 situations could cause hypotension?
Excessive anesthetic depth
Hypovolemia
Circulatory shock
Sepsis
Drugs - Ace, Propofol, Morphine, Inhalants
Histamine release
What 4 drugs cause hypotension?
Ace
Propofol
Morphine
Inhalents
What 5 situations could cause hypertension?
Inadequate anesthetic depth
Pain
Hypercarbia
Fever
Drugs - catecholamines, ketamine, A2 agonists
What 3 drugs reliably produce hypertension?
Catecholamines
Ketamine
A2 agonists
Which lead in an ECG is typically monitored during anes?
Lead II
What does an ECG tell you (2)?
HR
Rhythm
What 9 situations reliably produce tachycardia?
Inadequate anes depth
Hypotension
Drugs - Ketamine, Thiopental, Anticholinergics, Sympathomimetics
Hyperthermia
Hypercarbia
Hypoxemia
Anemia
Hyperthyroidism
Anaplylaxis
What 4 drugs reliably produce tachycardia?
Ketamine
Thiopental
Anticholingerics
Sympathomimetics
What 9 situations reliably produce bradycardia?
Excessive inhalation anesthetic depth
Drugs - Opioids, A2 agonists, cholinesterase inhibitors
Pre-existing cardiac disease
Vagal reflexes - oculocardiac, laryngeal/pharyngeal stimulation, visceral manipulation
Hyperkalemia
Hypertension
Hypothermia
Terminal hypoxemia
Cushing's reflex - high intracranial pressure
What 3 drugs reliable produce bradycardia?
Opioids
A2 agonists
Cholinesterase inhibitors
What 3 things stimulate vagal reflexes?
Oculocardiac
Laryngeal/Pharyngeal
Visceral manipulation
What is the Cughing's Reflex?
High intracranial pressure
What are 5 ways to monitor respirations?
RR
Resp depth
Respirometer
Capnometry
Pulse Ox
What are 3 ways to monitor RR/Depth?
Observe chest wall excursions
Observe rebreathing bag
Airway thermistor probe
4 ways to measure ventilation (RR and volume)
Chest wall movement
Breath sounds through esophageal stethoscope
Breathing bag movement
Airway thermister probe
What are the 2 aspects of ventilation?
RR
Resp volume
What are the 2 aspects of resp monitoring?
RR
Resp depth
What are the 2 ways to measure ventilation?
RR and volume
Minute volume
What are 3 ways to measure ventilation (minute ventilation - rate and volume)
Capnometry/Capnography
Blood Gas analysis
Respirometer
What is capnometry?
Continuous non-invasive measurement of CO2 concentration in inspired and expired air
What technology does capnometry use?
Infra-red abs tech
What does the end expired CO2 of capnometry correlate to?
Arterial CO2
What 3 situations reliably produce hypercarbia?
Hypoventilation
Dead space rebreathing
Hyperthermia
What is the most common reason for hypercarbia?
Anesthetic depression
What 8 situations can produce hypoventilation?
Anesthetic depression (MOST COMMON)
Airway obstruction
Intracranial disease
Neuromuscular disorders
Thoracic/abd restrictive disease
Pleural space fluid/air
Severe pulmonary disease
Iatrogenic (improper ventilation settings)
What is oxygenation?
Delivery of O2 to tissues
What is Oxygenation dependent on (2)?
CO
O2 content of blood
What is cardiac output dependent on (2)?
HR
BP
How can you measure oxygenation (3)
BP and HR
Hb (PCV)
SpO2 (pulse ox)
What does 1/3 PCV equal?
Hb
How can you calculate Hb?
1/3 PCV
What should PCV never fall below?
20%
What is pulse ox and how does it work?
Continuous real time estimates of arterial Hb saturation with O2; can detect hypoxemia early
Measures transmission of light at 2 wavelengths through a pulsatile vascular bed
Where can you put the pulse ox to monitor Hb (4)?
Tongue
Vulva
Penis
Ears
What is the lowest you can let Hb go to?
7 (1/3 PCV)
Name 5 factors that limit oxygen saturation
Low inspired O2 concentration
Hypoventilation
Pulm or pleural space disease - primary lung disease, pulm edema, atelectasis
Circulatory failure
Abn Hb
Name 2 conditions that result in abnormal Hb
Carboxyhemoglobin
Methemoglobin
Name 8 things that could interfere with pulse ox measurements
VC - hypothermia or drug induced
Motion
Shivering
Ambient light
Pigmentation
Poor sensor positioning
Carboxyhemoglobin
Methehoglobin
Does pulse ox detect anemia?
no
What is normal pH?
7.35-7.45
What is normal pO2?
5x FiO2
What is normal pCO2?
35-40 mmHg
If room air is 20% O2, then what is the patient's pO2?
100%
If patient is breathing 100% O2, then what is his pO2?
500%
What is normal HCO3?
23-26
What is normal base excess?
-5 to 3
What are the 9 criteria for euthanasia?
Without pain, distress, anxiety, or apprehension
Short time to loss of consciousness
Reliable and irreversible
Safe for personnel
Compatable with requirement and purpose (food animal - no barbiturates)
Performed with available drugs or equipment
Compatable with species, age, and health
Equipment is easily maintained
Safe for predators and scavengers
Can you use barbiturates for food animal euthanasia?
NO
What is the national average adoption rate?
24%
What is the biggest cause of employee turnover in the shelter?
Dealing with euthanasia
Name the 3 modes of action of euthanatizing agents
Hypoxia
Direct depression ofneurons necessary for life function
Physical disruption of brain activity and destruction of neurons necessary for life
Is hypoxia acceptable in awake patients?
NO
What is hypoxia?
Induction of paralysis (lack of respiration) resulting in hypoxia
Name the 2 ways you can induce death via hypoxia
CO
CO2
(N2O and argon are conditionally acceptable methods)
How does CO cause death?
Combines with Hb preventing its combination with O2
Does CO cause death immediately?
No, but it is insidious
What are 3 limitations (to personnel) to using CO to euthanize an animal?
Very hazardous to personnel
Cumulative
Dificult to detect
Which species is CO suitable for?
Most small species
What are the latest recommendations for source of CO?
Bottled gas
What does euthanasia via CO require?
Properly designed chambers (cannot leak!!)
What percent CO is used to cause euthanasia?
6%
How quickly does collapse occur when using CO to cause euthanasia?
.5-2 min
How quickly does death occur when using CO to cause euthanasia?
5-7 min
How does CO2 cause death?
Depresses vital centers (cerebral cortex, subcortical structures, and myocardium)
What areas of the body (3) are affected by CO2 during euthanasia?
Cerebral cortex
Subcortical structures
Myocardium
Name 2 benefits of using CO2 to cause euthanasia.
Moderately rapid
Minimal hazard to personnel
Where is the animal placed when performing euthanasia with CO2?
Closed chamber
Is the time to death longer or shorter for immature and neonates using CO2?
Longer
What species is CO2 used for to cause euthanasia?
Lab an
Cats
Sm dogs
Rabbits
Amphibians
Fish
Reptiles
Swine
How does nitrogen and argon produce death?
Displaces O2 (inspired O2 less than 2% must be produced rapidly)
Should animals be anesthetized/sedated before euthanasia with Nitrogen/argon?
YES
What should you warn O about when inducing death via hypoxia?
Some reflex (not censcious) motor actvity may be maintained
What are 6 ways to produce death via direct depression of neurons necessary for life?
Inhalant anesthetic drugs
Barbiturates
Chloral hydrate
T-61
MS 222 (amphibians and fish)
Any inhalant anesthetic can be used for euthanasia except _____
N2O (not reliable)
What inhalant anesthetic is most effective at causing death and for what 2 reasons?
Halothane
Reasonably rapid induction
Non-offensive odor
What is a problem with using isoflurane as a euthanasia device?
Pugnant odor (animals hold their breath - may require more drug)
Should you put animals euthanized with ether in the fridge?
NO - clicks on and explodes
For what size animals are inhalant anesthetics useful?
Small animals - venipuncture is difficult
What is the number 1 anesthetic used to euth an?
Pentobarb injection
What if you give pentobarb (to euth) to the wrong animal (3)?
Alkalinize the dog
Give fluids
Diurese
What are 4 advantages to using barbiturates for euth?
Rapid onset of action
Smooth induction
Minimal discomfort
Less expensive than other agents
Name 5 disadvantages to using barbiturates for euth.
Req IV injection
Restrain each animal
Drugs must be strictly accounted for
Terminal gasps
Drugs persist in env - wildlife issue and food issue
What type of injection (for euth) can you use if IV injection is distressful or dangerous?
Intraperitoneal
When can you use intracardiac injections for euth?
ONLY if the an is sedated, unconscious, or anesthetized
What does chloral hydrate do and how does it cause death?
Cerebral depression
Hypoxemia
Chloral hydrate is an acceptable type of euth in ____ animals only if the animal is ______ and the drug is admin ______
Large animals
Heavily sedated and administered IV
Can chloral hydrate be used in SA to produce death?
NO - side effects (movement with induction)
Where can you get T-61?
Canada
What 3 types of drugs make up T-61?
Gen anesthetic
Curariform
Local anesthetic
What is the only way T-61 can be admin?
IV
What are 2 perks of using T-61 for euth?
No terminal gasps
No movement
Is KCl acceptalbe as the sole euth agent?
NO - must be under gen anes
What 2 ways can KCl be admin?
IV
Intracardiac
(only after under gen anes)
What are the 3 injections given to people for capital punishment?
Sodium thiopental - induce sleep
NM blocker - paralysis
KCL - stop heart
What is the biggest problem with capital punishment?
Finding a vein
Name 2 acceptable physical methods of euth
Penetrating captive bolt
Microwave induction
What is the advantage to using penetrating captive bolt?
No free projectiles
What is the disadvantage to using penetrating captive bolt?
Aesthetically displeasing
Name 5 species penetrating captive bolt can be used in.
Ruminants
Horses
Swine
Rabbits
Dogs
(anything used for food)
Name points you can hit on an animal using penetrating captive bolt.
Forehead
Medulla (behind the head)
What 2 species can you use microwave irradtiation on for euth?
Mice
Rats
What is the advantage to using microwave irradiation for euth?
Loss of consciousness in less than 100 ms and death in less than 1 second
What are 2 disadvantages to suing microwave irradiation for euth?
V expensive
Only for v sm an
Are the following conditionally or always acceptable forms of euth:

Euthanasia by blow to head
Cerv dislocation
Decapatation
Electrocution
Gunshot
Thoracic compression
Conditionally acceptable
Name 3 adjunctives to euth
Stunning
Pithing
Exsanguination
Name 3 things you can use in conjunction with stunning/pithing
Pharm agents
Exsanguination
Decapitation
Is death ensured with stunning/pithing?
No
How quickly is consciousness lost with stunning/pithing?
Rapidly
Can exsanguination be used as a sole means of euth?
NO
What should you tell an o that wants to witness the euth (6)?
There is a potential for:
Vocalization
Mucle twitches
Failure of eyelids to close
Urination
Defecation
Agonal resp
Why should you not place an ECG on a euth patient?
Heart may continue to ave electrical activity for up to 10 min
How should you confirm death in euth patient?
Listen to heart and watch for resp then listen to heart again 5 min later
If you sedated the animal prior to euth, will you need more or less euth drug?
Use more or else may take animal longer to die (not necessarily longer to fall asleep)
What is pain?
An aversive sensation and feeling associated wtih actual/potential tissue damage; a protective mechanism for the body
Name the 5 pain pathways
Transduction
Transmission
Modulation
Projection
Perception
What are the 2 types of pain?
Pathologic
Physiologic
What are the 2 types of pathologic pain?
Peripheral
Central
What is physiologic pain?
Activation of high threshold peripheral pain receptors (nociceptors) by painful noxious (thermal, mechanical, chemical) stimuli; minimal tissue damage; a protective warning
What is pathologic pain (2)?
Pain generated by activation of nociceptors
Pain generated by impulse that would not normally produce pain (non-nociceptor mediated)
What 3 types of injury can cause pathologic pain?
Inflammation
Neuro pain
Cancer pain (?)
What is a nociceptor?
High threshold peripheral pain receptors
How do you cause non-nociceptor mediated pain (2)?
Increase excitability
Decrease Inhibitory substances
What is stress?
Biological responses in an attempt to cope with disruption/threat to homeostasis
What are the 2 locations of pain?
Somatic (skin, bones/tendons)
Visceral (organs)
What are the 2 types of somatic pain?
Supf
Deep
What are the 3 mechanisms of pain?
Inflamm
Mechanical
Idiopath
What are the 3 types of sensitivity to pain?
Primary hyperalgesia
Secondary yperalgesia
Central algesia
What are 4 ways to evaluate pain?
Behavior - Attitude, activity, appetite
Physiology - HR RR, BP
Blood cortisol - cortisol and catecholamines
Response to mainpulation - palpation, phys stimulation
What are the 4 components of pain scoring system?
Behavior - attitude, activity, appetite
Severity of pain
Duration of pain
Mechanism of pain
Name the 4 therapeutic approaches to pain.
Preemptive
Multimodal
Mechamism based - target drug for specific pain
Integrated
What is the best type of drug for treating acute pain?
Opioids
What 3 things do opioids produce?
Analgesia
Euphoria
Sedation
Which opioid receptor is most often used for analgesia
Mu
Why do you worry when using an opioid in a horse?
dECREASED GI function
Are the following opioid agonists or agonists/antagonists:
Morphine
Methadone
Meperidine
Fentanyl
Hydromorphone
Oxymorphone
Agonists
Are the following opioid agonists or agonists/antagonists:
Pentazocine
Butorphanol
Buprenorphine
Nalbuphine
Nalorphine
Agonists-antagonists
What is a common opioid antagonist?
Naloxone
What 3 things do A2 agonists provide to patient?
Sedation
Musc relaxation
Analgesia
What anesthetic drug is most often used in horses for colic pain?
A2 agonists
Name 4 commonly used A2- agonists
Xylazine
Detomidine
Romifidine
Medetomidine
Name 3 A2 antagonists
Yohimbine
Tolazoline
Atipamazole
Which has a higher A2:A1 ratio:
Xylazine
Medetomidine
Medetomidine (1620:1)
How do local anesthetics work?
Block Na channels and decrease nerve transmission (sensory and motor)
Name 4 local anesthetics
LIDOCAINE
Mepivacaine
Bupivacaine
Ropivacaine
Name 3 contraindications for epidurals
Coagulopathy
Skin conditions
Hypotension
Name 4 situations that you should use pain busters
Spinal trauma
Amputation
TECA
Neuroma
Is the lidocaine patch absorbed systemically?
NO
What 3 drug combo do you use for severe pain?
Morphine
Lidocaine
Ketamine
(put all 3 in same syringe)
What 4 pathways does inflammation activate?
Phoppholipase A2
Cyclo-oxygenase (COX)
Lipoxygenase (LOX)
Nuclear factor kappa beta (NFkB)
Phospholipids + phospholipase =
Arachadonic acid
Arachadonic acid + COX =
Prostaglandins
Arachadonic acid + LOX =
Leukotrienes
Do COX 2 selective inhibitors exert analgesic effects on (peripheral or central) COX2
BOTH
What 3 things do NSAID provide?
Antiinflamm
Antipyretic
Analgesic
What 2 things does COX2 inhibition provide to patient?
Decreased inflamm peripherally
Decreased sensitization in dorsal horn of spinal cord
Which isoform in inducible (COX1 OR COX2)
COX2
What 2 things does COX1 produce and what are their effects?
Prostaglandins (PGE2) - VD effect on kidneys
Prostacyclin - antithrombogenic when released by endothelium and cryoprotective when released by gastric mucosa
What induces COX2?
Inflammation
What do corticosteroids do to COX2
Blocks COX2
Why is it not always beneficial to block COX2 (2 reasons)
Constitutive in certain tissues
Physiologic functions - wound healing
How do NSAIDS work?
Block COX
Are opioids useful for chronic pain?
NO (<2 days)
Name 5 common side effects of NSAIDS
Gastric distress
Renal damage
Antithrombic effect
Hypersensitivity reactions
Hepatopathy (Carprofen in labs esp)
Are NSAIDS useful for chronic pain?
YES (esp arthritis)
What does a ratio of <1 and >1 mean in regards to NSAIDS?
<1 = COX1
>1 = COX2
Do all NSAIDS exhibit COX1 AND COX2?
Yes (to some extent)
Are aspirin and ketoprofen <1 OR >1?
<1 (COX1)
Are carprofen, deracoxib, and meloxicam <1 or >1
>1 (COX2)
Which NSAID is most COX1?
Ketoprofen
Which NSAID is most COX2?
Deracoxib
What could COX2 NSAIDS cause that COX1 does not?
Glaucoma
What additional benefit does COX2 have that COX1 does not?
Anti-angiogenic (in addition to the usual antiinflamm, antipyretic, and analgesic properties of all NSAIDS)
Name 6 analgesic adjuncts that can be used with NSAIDS and an example of each
Dissociative ketmine
Anticonvulsant - gabapentin
Tricyclic antidepressant - amitryptyline
Central analgesics - tramadol
Phenothiazines - ace
Alternative therapy - acupuncture, massage, etc.
Is deracoxib more or less likely to cause gastric ulcers than aspirin?
Less
Are the following acceptable ways to use locals?
Inject into SQ to desensitize nociceptors
Inject into areas near nerves
Inject into epidural and subarachnoid space
Inject intra-articularly
Spray on MM
Apply to intact skin
yes
What is a disadvantage to applying a local to intact skin?
Limited absorption
How do locals work?
Stabilize membranes (decreases nerve impulses) by binding to NA channels which prevents the depolarization process
Locals are weak acids or weak bases?
Weak bases
Do locals dissociate into ionized or unionized forms in water?
BOTH
Is the ionized or unionized for of a local more water soluble?
Ionized
How are locals purchased (acidic or basic/solution or solid)?
Acidic solution
Since locals are purchased in an acidic solution, are they more ionized or unionized?
Ionized
Once the local is injected into the body, does it form more ionized or unionized particles?
Unionized (was originally in a highly acidic solution making it highly ionized)
Is the unionized local anesthetic form more or less lipid soluble?
More lipid soluble - important for diffusion through cell membranes to reach Na channels
What must the unionized local anesthetic do in the cell before impacting the Na channel?
Go back to the ionized form
How are local anesthetics metabolized?
Liver
What does the ratio of ionized to unionized local anes form depend on (2)?
pKa of drug
pH of env
What 2 things does a drug's pKa determine?
Degree of ionization
Onset of action
As the pKa of a drug is increased, there is (more or less) freely diffusable drug available (at tissue pH 7.4)
Less (therefore the onset of action is delayed)
pKa of Bupivacaine = 8.1
pKa of Lidocaine = 7.6
Which has a slower onset of action?
Bupivacaine
Are locals (more or less) effective in an acidic env and why?
Less because less uncharged drug is present
Does tissue with infection adn swelling have a higher or lower pH?
Lower
Is the ionized or unionized for of the drug responsible for its action?
Ionized
What are 2 addtional factors that affect activity of local (besides pKa and pH)
Protein binding
Lipid solubility
As the protein binding of a drug is increased, the duration of the anesthetic effect is (prolonged or shortened)?
Prolonged
If lidocaine is more protein bound than procaine (80% vs 60%) then which has a longer duration of action?
Lidocaine
As the lipid colubility of a drug is increased, the potency and toxicity are (increased/decreased)?
Increased
If bupivicaine is more lipid soluble than lidocaine (27 vs 3) then which is more potent and potentially toxic?
Bupivicaine
What are the 3 types of nerve fibers?
Motor
Autonomic
Sensory
Nerve fibers are classified as large and small depending on (2)?
Diameter
Degree of myelin coating
The more myelin, the (faster or slower) an impulse travels?
Faster
The more myelin, the (easier or harder) it is to block?
Harder (large nerve fibers have more myelin making them more difficult to block)
How many nodes of ranvier do you need to block if there is myelin?
3 (if no myelin then need to block shorter seg)
Which 2 types of nerve fibers control pain?
A-delta
C
Are A-delta and C fibers bigger or smaller?
Smaller
Are A0delta and C fibers more easily blocked?
YES
Which is blocked first:
Pain and temp
Touch and motor
Pain and temp
Can a broken legged dog with a local anes block be pain free and still move its limb?
YES
What are fibers called that are on the outer side of the nerve?
Mantel fibers
What are fibers called that are on the inner side of the nerve?
Core bundle
The mantel fibers supply the (distal or proximal) parts of the body?
Proximal
If blocking the arm with a local,which is anes first (shoulder or fingers)?
Shoulder
What regains sensation first (shoulder or finger)?
Shoulder
When do you know the patient is fully recovered from local anes?
When they can move fingers/toes
Does co-admin of EPI and a local shorten or prolong the duration of the local?
Prolong (EPI is a VC)
Does hyaluronidase speed up or slow down the onset of action of a local anes
Speeds up (and broadens the effets)
Does hyaluronidase enhance or restrict the systemic absorption of a local?
Enhances absorption (potentially increases the toxicity)
Which site of injection provides the shortest onset to time of activity?
Intrathecal
Which site of injection provides the longest onset to activity?
Peripheral nerve block
During pregnancy, will the ester linked local anes be prolonged or shortened and why?
Prolonged (plasma cholinesterase activity is reduced)
What are 4 clinical signs of toxicity and their order of appearance?
Seizure
Apnea
Hypotension
Death
What 3 factors determine the concentration of local anes in systemic circulation (and therefore toxicity)?
Dose
Abs rate
Metabolism
What was the first local anes used (1885) and why is it still used today?
Cocaine
VC properties
What was the first nontoxic local anes used (1905)
Procaine
What is the order of appearance for the following drugs in history?
Bupivacaine
Lidocaine
Mepivacaine
Ropivicaine
Lidocaine 1940
Mepivacaine (Carbocaine) 1960's
Bupivacaine (Marcaine) 1965
Ropivacaine (Naropin) 1996
What are the 3 chemical components of local anes?
Aromatic ring
Intermediate chain (ester or amid linkage)
Secondary or tertiary amine
Name 2 ester linked local anes
Cocaine
Procaine
Name 2 amide linked local anes
Lidocaine
Ropivacaine
Why are ester linked local anes great?
Rarely see allergic rxns
Why are ester linked local anes not great?
Short anes duration (<1hour) - rapidly metabolized in the blood
Procaine has a (high/low) potency and a (long/short) duration
Low potency
Short duration
How can you prolong procains duration of effect?
Give with penicillin (forms salt and delays absorption and prolongs duration of effect); procaine is in excess of the penicillin so there is an immediate local anesthetic effect
What local is dropped in the eye to desensitize the cornea for minor procedures and tonometry?
Proparacaine
Why are amide local anes great?
Have an intermediate/long anes duration (2-8 hours) due to liver metabolism
What is a disadvantage of using amide-linked drugs?
Allergic reaction
Name 2 local anes that have an intermediate potency (2 hours)
Lidocaine
Mepivacaine
Name 2 drug that have a higher potency (4-8 hours)
Bupivacaine
Ropivacaine
What local anes is also an antiarrhythmic?
Lidocaine
What 2 local anes are the most widely used in vet med?
Lidocaine
Mepivacaine
What is lidocaine spray used for (2)?
To desensitize the larynx when performing ET intubation (gorillas and cats)
Desensitize the urethra
What is ELMA cream?
Eutestic Mixture of Lidocaine and Prilocaine
Is EMLA cream absorbed through intact skin?
Yes (lipid soluble)
Does EMLA cream have a prolonged time to effect?
Yes - 60 min
What is a eutectic mixture and give an example?
The individual components are soluble in each other and the resulting compound has a lower melting point than the components
A 50:50 mixture of lidocaine powder and prilocaine powder for an oil that penetrates intact skin better than either drug alone
What is Cetacaine and why could it cause in cats?
A local benzocaine spray used for ET tubing humans
Causes methemoglobin in cats (so use lidocaine instead)
Does xylazine have local anes properties?
Yes (3-4 hour duration)
What is sometimes used as an epidural in cattle and horses?
Xylazine
If a local anes is given intra-op, what does it prevent?
Wind up
What can locals be used in combo with (2) to produce a cooperative patient?
Sedation
Tranquilization
Why are locals used when an animal is under gen anes?
inimizes the req concentration of the inhalent
Why are locals used before surgery?
Provides post-op pain mgt
Why are locals better than opioids post-op?
Muscle relaxation
What is the easiest, most reliable, and safest local anes technique?
Direct injection of local drug into tissue
What should you do to the lidocaine if desensitizing large areas?
Dilute lidocaine with sterile saline solution
What is the magic number to keep the lidocaine dosage under?
10mg/kg
What is a side effect of lidocaine?
Seizures
What local is used most often?
Lidocaine 2%
What are 2 ways to use a local?
Mult intraderm/SQ injections of 0.5ml of lidocaine
Slow injection local anesthetic while advancing the needle along the line of proposed incision ("linear infiltration"/"line block")
Why can't you inject locals IV (2)?
Toxicity
Not effective
What do you do to absorption, local anes effect, and duration (up to 50%) if combining EPI with a local?
Reduce absorption
Increase local anesthetic effect
Increase local anesthetic duration
What body locations should EPI not be injected into and why (3)?
Tissues supplied by end arteries (ears, tail)
VC
Local ischemia
Necrosis
Excessive doses or inadvertent IV admin of locals may cause (4)?
Seizures
Apnea
CV collapse (hypotension)
Death
What is a painbuster?
Catheter placed in a wound and tunneled out the side to deliver local anes for many hours without mult injections
What percent lidocaine do you normally use?
1-2%
What percent ropivicaine do you normally use?
0.2%
In dogs, what size needle and how much lidocaine is normally used?
22 gague
1-2ml
Why (2) is ropivicaine better than lidocaine?
Lasts 2x as long
Rapid onset of action
What anatomic structures (4) does a maxillary nerve block block?
Maxilla
Upper teeth
Nose
Upper lip
Where (2) can you insert our needle for a maxillary nerve block?
Floor of orbit
Infraorbital foramen
What anatomic structures (4) does the mandibular alveolar nerve block block?
Canine
Incisors
Skin and mucosa of chin
Skin and mucosa of lower lip
Where can you block the mandibular alveolar nerve in a horse?
Mental foramen
What 2 nerves do you block for dehorning?
Cornual branch of the zygomaticotemporal nerve
Infratrochlear nerve
What 3 nerves do you block for a declaw and what local anes drug can you use?
Radial (0.3ml)
Medial (0.3ml)
Ulnar (0.3ml)
(block nerves just above the carpus!!)
0.2% Ropivacaine
What 2 drugs can you use in a declaw chronically, and why can't you used NSAIDS?
Buprenorphine
Tramadol
NSAID cause problems in cats
What type of nerve block is used for standing surgery in cattle and where can you inject and what does it block?
Paravertebral nerve blocks
Lateral processes of T13, L1, L2
Blocks the flank
Why can't you inject a local after L3 in cattle?
Causes weakness in hind limbs
What is IVRA and why is it used?
Intravenous Regional Anesthesia
For anesthesia of an extremity distal to a tourniquet
What are 2 reasons a tourniquet is useful in surgery?
Helps with hemostasis
Keep local anes in the area
Name 2 procedures that a blood free surgery site is ideal for (and therefore you should use IVRA)
Removing FB from paws
Taking biopsies
Where is the tourniquet placed for IVRA in the foreleg and hindleg of a horse.
Proximal to elbow for surgery of front leg
Proximal to hock for surgery of hind leg
Where is the 2% lidocaine injected when doing a IVRA?
IV!!!!!!! (make sure the tourniquet doesn't slip!!!!)
One IV local anes injection = ____ specific nerve injections
6
How quickly will regional anes of the limb be with IVRA and how long will it last?
Within 10 min
As long as tourniquet is on
What is the max amount of time the touniquet should remain on with IVRA?
2 hours
What happens in tourniquet is left on for 4 hours? 8 hours?
4 - reversible shock
8 - death (sepsis and endotoxemia)
What is a usual problem with the animal that had IVRA?
Parasthesia in limb (usually reversible)
What 4 reasons are intercostal nerve blocks uesful for?
Chest laceration
Rib fractures
Placement of chest tube
Postop analgesia after thoracotomy
How many intercostal spaces should you block before/after in interecostal nerve block and why?
2-3 before
2-3 after
Considerable overlap of nerve supply
Where should the needle be inserted for an intercostal nerve block?
Caudal to rib near the intervertebral foramen
Why use an epidural?
Produce anesthesia caudal to the umbilicus
What 4 sx procedures should you use an epidural for?
C-section (little anes gets to the fetus)
Sx of rear quarter
Repair pelvic fracure
Perineal sx
Where do you give an epidural?
Midline of LS (L7-S1) space (just caudal to wings of ilium)
Is the epidural places cranial or caudal to the wings of the ilium?
Just caudal
You should feel a distinct pop when the epidural needle is advanced through the ______
Interarcuate ligament (lig. flavum)
Should there be spinal fluid or blood apriated during epidural?
NO
Should there be resistance when injecting epidural?
NO
Which animal has the longest spinal cord?
Pig
How long does a lidocaine epidural last?
1.5 hours
How long does a bupivacaine or ropivacaine epidural last?
3-5 hours
Name 4 advantages of epidural
Good musc relaxation
Postop analgesia
Min effects on the body (maybe some hypotension)
Low cost
Name 4 potentail complications of an epidural
Inadequate anesthesia - animal is awake during sx
Sx time is limited
Hypotension
Resp depression/apnea
Why should you never block the caudal cervical vertebrae?
Phrenic n. is here which innervates the diaphragm
If you give an excessiv amount of anes for an epidural, what 2 things may happen
Hypotension
Resp depression/apnea
What is the one requirement if using an opioid for an epidural
Must use preservative free morphine(ASTRAMOPH)
What is the onset of analgesia when using an oioid for an eidural?
1-2 hours
Qhat is the duration of analgesia when using an opioid for an epidural?
8-12 hours
Name 5 advantages of using an opioid epidural
Profound somatic/visceral pain relief
No motor blockade (great for total hip sx)
No sensory blockade
Ne depression of sympathetic nervous system
Reversal of systemic side effects with naloxone