lecture exam 2 study questions

what are the two most commonly used inhalation anesthetic agents in the US?

isoflurane and sevoflurane

which inhalation anesthetic is supplied as a compressed gas?

nitrous oxide

what is an inhalation anesthetic used since the 19th century and still occasionally used in research that is highly flammable?

diethyl ether

what are the general characteristics of halogenated anesthetics? Why are they "halogenated"?

- they are liquid at room temperature, stored inside the vaporizer of the anesthetic machine and evaporate into oxygen entering vaporizer, then delivered to patient through breathing circuit/ET tube

- they are halogenated because they have halogens in their chemical formula

are isoflurane and sevoflurane low vapor pressure or high vapor pressure inhalant anesthetics?

they are high vapor pressure inhalant anesthetics

what type of vaporizer is used for high vapor pressure anesthetics?

a precision vaporizer

what does MAC stand for?

minimum alveolar concentration

what is the definition of MAC?

the lowest concentration of anesthetic in alveolar gas at which 50% of patients show no response to a painful stimulus

what is the MAC for isoflurane?

1.3%

what is the MAC for sevoflurane?

2.4%

to maintain a patient at a light anesthetic depth, the vaporizer would usually be set at

1x MAC

to maintain a patient at a moderate anesthetic depth, the vaporizer would usually be set at

1.5x MAC

to maintain a patient at a deep anesthetic depth, the vaporizer would usually be set at

2x MAC

what is the relationship between MAC and potency?

the lower the MAC, the more potent the anesthetic

what are the light, moderate and deep vaporizer settings for isoflurane and sevoflurane?

light iso- 1.3

moderate iso- 1.95

deep iso- 2.6

light sevo- 2.4

moderate sevo- 3.6

deep sevo- 4.8

what is the relationship between partition coefficient (solubility of the anesthetic agent in blood) and rate of induction?

- the higher the partition coefficient, the longer the rate of induction

- lower partition coefficients are faster acting, and also are eliminated from the patient faster

compare the parturition coefficient of isoflurane and sevoflurane

sevoflurane has a partition coefficient of 0.65 and acts faster than isoflurane with a partition coefficient of 1.4; this is despite the fact that isoflurane is a more potent anesthetic

isoflurane is labelled for use in which species? what about sevoflurane? what species are these agents used in?

isoflurane- dogs and horses

sevoflurane- dogs only

they are used in domestic, exotic, and zoo animals

how are isoflurane and sevoflurane metabolized and eliminated from the body?

they undergo minimal liver metabolism and renal excretion because they are eliminated from the body through the lungs

what are the analgesic properties of isoflurane and sevoflurane?

none

what is the effect of iso/sevo on temperature? resp rate? tidal volume? heart rate? blood pressure?

hypothermia, lower resp rate, tidal volume, hr, and blood pressure

isoflurane and sevoflurane have similar clinical applications. identify some clinical situations in which one agent is preferred over the other.

for mask and chamber induction, sevoflurane is preferred because it is less irritating and smells better than isoflurane

what is the benefit of using nitrous oxide along with another inhalant anesthetic?

- when used with other agents, it speeds induction and recovery and provides additional analgesia

- it also reduces the MAC and therefore vaporizer setting of other anesthetic agents by 20-30%, which reduces the risk of adverse effects on the cardiovascular, pulmonary, and other systems

barbiturates were once widely used as anesthetics, but now are largely replaced by other drugs. identify two barbiturate drugs still used on a regular basis in veterinary medicine (not necessarily as anesthetic agents)

phenobarbital, pentobarbital

identify two ultra short acting anesthetic agents used in veterinary medicine that are not barbiturates

propofol and etomidate

identify two dissociative anesthetic agents used in veterinary medicine.

ketamine and tiletamine

what are tissues in the Vessel Rich Group (VRG)? what is the significance of these tissues for anesthetics administered IV?

- brain, heart, liver, kidneys

- they have a large blood supply, so large amounts of drugs are available in these tissues soon after injection

what is the difference between redistribution, metabolism and excretion?

- redistribution is when levels of a drug in the bloodstream drop below level in the brain, then the drug leaves the brain and goes to the body tissues, muscles, and fat. also plays a role in the recovery from anesthetics

- metabolism is blood circulates through the liver; the drug is metabolized to inactive substances

- excretion is when blood circulates through the kidneys, the drug or its metabolites are excreted over a period of hours to days the drug is eliminated from the body

like thiopental, propofol and alfaxalone are both ultra short acting anesthetics administered IV. Compare these two drugs. How long does it take for the drug to be redistributed? How does redistribution affect anesthetic depth? How long does it take for the drug to be metabolized? Thiopental has a much longer half life than propofol or alfaxalone -knowing this, can you explain why we can safely use propofol or alfaxalone to maintain anesthesia, but not thiopental?

Propofol and alfaxolone have a mild to marked CNS activity, a decrease in body temp. Propofol has a decrease in HR while alfaxalone either has an increase or little to no effect in HR

Propofol- within 30-60 secs; alfaxolone- every 15 secs of bolus

It affects anesthetic depth where the drug is distributed to various tissues based on blood flow. Absorption and distribution is more rapid in vessel rich tissues

is propofol a controlled substance? can it be administered IM? does it have analgesic properties?

no, no, and no

is alfaxalone a controlled substance? can it be administered IM? does it have analgesic properties?

- schedule IV - IM use off label at lower does to produce deep sedation - no

propoflo (propofol) may be used in cats, but cats may have a toxic reaction to propoflo 28. why?

because it contains benzyl alcohol as a preservative, which can cause benzyl alcohol toxicity in cats

what are the likely complications of administering propofol rapidly, rather than over 30 sec to a minute?

pt will become apneic and hypotensive

a very cautious new technician administers propofol very, very slowly and the patient starts thrashing and crying out. what do you think is happening?

the patient is more than likely in stage 2 anesthetic depth where involuntary movements can occur

what potential complication should you prepare for anytime you are administering alfaxalone?

respiratory depression

compare etomidate and propofol. what are the similarities?

both are not controlled, ultra short acting non barbiturate injectables with a wide margin of safety and rapidly metabolized. etomidate has little effect on resp and CV systems, but propofol does cause resp depression and hypotension

what are some benefits of etomidate compared to propofol?

- the benefit it is very useful with high risk patients

- etomidate decreases brain oxygen consumption, maintains brain perfusion better than most injectable anesthetics, and has anticonvulsant properties, making it better for pt with brain trauma or undergoing brain ot spinal surgery

ketamine does not induce ___________________, but produces a ____________________ state

unconsciousness, cataleptoid

how does ketamine affect reflexes used to monitor anesthesia-eye position, pupils, muscle tone?

- eye position usually remains fully open with a central and dilated pupil

- in some animals muscle tone is retained, where in others it is increased almost to the point of rigidity

how does ketamine elimination differ in the cat compared to other species?

it is excreted directly through the kidneys

is ketamine a controlled substance? what are routes of administration for ketamine? how does route of administration affect onset and duration of anesthesia? does it have analgesic properties?

- yes, schedule III

- IV, IM (cats), orally (cats)

- IV has faster induction, recovery, and is a lower dose than IM

- yes

what is the effect of ketamine on cardiac and respiratory function? compare to propofol.

it has minimal cardiac and resp depression

telazol contains ________ , which is a ________ anesthetic and ________ which is a ________ like diazepam.

tiletamine, dissociative, zolazepam, benzodiazepine

is telazol a controlled substance? how can telazol be administered? how does rate of administration affect onset and duration of anesthesia? does it have analgesic properties?

- yes, it is schedule III

- it is administered IV (onset less than 60 secs), SQ, or IM (onset between 3-6 mins)

- yes

do we use analgesics to treat physiologic pain? explain your answer.

yes

what is multimodal analgesia?

using a combination of drugs to provide adequate analgesia while minimizing side effects

compare acute vs chronic pain- give a clinical example of each

- acute pain is pain that has an immediate onset after a tissue injury and resolves when healing is complete. examples are pain from surgery, trauma, or medical conditions.

- chronic pain is pain that lasts weeks, months, years and persists after the tissues have healed or when they will not heal.

examples are osteoarthritis and cancer

compare somatic vs visceral pain- give a clinical example of each

- somatic pain is from the musculoskeletal system.

examples are bone fracture and skin incision.

- visceral pain is coming from the organs.

examples are pleuritis, pancreatitis, or colic

what is the difference between superficial and deep pain? are these terms used to describe visceral pain or somatic pain?

superficial pain is skin pain, deep pain is joint, muscle, bone pain. they are used to describe somatic pain.

identify the different mechanisms or fundamental types of pain.

- incident (trauma, surgery)

- breakthrough (chronic pain, cancer)

- neurogenic (nerve injury)

- idiopathic

What are nociceptors? Anatomy review: What is the difference between a nerve and a neuron? Are nociceptors part of the CNS or PNS? Are they sensory neurons or motor neurons?

- most abundant sensory receptors; some are mechanical receptors, others chemical or thermal receptors

- they are part of the CNS

- they are sensory neurons

describe the difference between primary and secondary hyperalgesia. what is a common name for secondary hyperalgesia?

- mediators released from damaged cells and from inflammatory cells increase sensitivity of nociceptors in the area of the injury

- interneurons in spinal cord involved in modulation become hyperexcitable if repeatedly stimulated; "normal" stimulus anywhere in area supplied by same spinal nerve may elicit pain; called "wind up" pain

the Colorado State University Canine and Feline Acute Pain Scales are numeric rating scales. why does this system provide more consistent results that the simple numeric rating scale?

because the scales have descriptors for each category.

the Glasgow Composite Measure Pain Scale is a categorical numeric rating scale. what makes this type of assessment superior to other types of pain assessment? what is the major disadvantage to using a system like the Glasgow Pain Scale?

- assess various physiologic and behavioral indicators of pain, assign a numeric value to each

- add values for all parameters to arrive at total pain score

- it is more time consuming to perform

what are the 2 categories of drugs most often used as analgesics in veterinary patients?

opioids and NSAIDs

what is the origin of opioid drugs? what receptors do these drugs act upon in the body?

they are natural or synthetic derivatives of opium, from poppies; mu, kappa, or delta CNS receptors

what are the most likely adverse effects of opioids on the respiratory system? the GI system? what other adverse effects do we see, especially in cats and horses?

- respiratory depression

- GI- may initially cause vomiting in small animals, followed by ileus, constipation, in horses may lead to colic

- cats can develop hyperthermia and horses sweat and they both get mydriasis

what are some advantages of NSAIDs compared to opioids?

they do not affect the CNS, do not depress respiration or cardiovascular function, and they are not controlled

what are the most common adverse effects of NSAIDs? what measures should be taken to prevent these adverse effects in patients undergoing anesthesia & surgery?

- renal toxicity and GI ulceration

- can avoid renal toxicity by maintaining circulating fluid volume and maintaining BP

- can avoid GI ulceration by giving gastric mucosal protectants and educating clients on what not to give their pet

what is cold laser therapy? what are benefits of cold laser therapy? what is safety precaution for using cold laser therapy?

- it is application of laser light by contact or noncontact in a perpendicular orientation to the skin

- benefits are treatment of chronic pain, relief of surgical or trauma wound pain, and promotion of healing and reduction of inflammation

- there are few studies done

what is physical therapy? what is goal of physical therapy?

- it is use of a variety of techniques like underwater treadmill or massages

- the goal is reduction of disability and restoration of normal function

what's the difference between an anesthetic agent and an anesthetic adjunct?

anesthetic agent causes a loss of sensation with or without a loss of consciousness, an adjunct is used in conjunction with an agent

where are Alpha 2 receptors located in the body? what do Alpha 2 agonists do?

- they are located on the cells in the sympathetic nervous system

- they bind to these receptors and inhibit the release of norepinephrine which provides a negative feedback; they can be used for sedation, analgesia, and muscle relaxation and can be used alone or in combination with other anesthetics

what are the routes of administration? how does route of administration affect onset, duration of sedation? (a2 agonists)

- IM and IV

- IM onset is in 15-30 mins and duration is 1-2 hours

- IV onset is 5-15 mins and duration is up to 1 hour.

are alpha-2 agonists controlled drugs?

no

why are these drugs reversible? what are the reversal agents for these drugs? what is the route of administration for the reversal agents? (compare small animals vs large animals) (a2)

- because of the adverse cardiovascular effects and long duration of sedation they cause

- yohimbine, tolazoline, atipamezole

- in small animals give reversal agent IM, even if you gave sedative IV (reversal agent given IV in large animals)

what is the effect of these drugs on the cardiovascular system? (a2)

they depress it; bradycardia, hypotension

what is a common adverse effect of alpha 2 agonists, especially in cats?

vomiting

do these drugs have analgesic properties? (a2)

yes

acepromazine is a phenothiazine _____________ .

tranquilizer

what are the routes of administration? what is the typical time of onset and duration of action of acepromazine?

- SQ, IV, IM, po

- IV onset is 15 min, IM onset is 30 min, duration of action is 3-6 hrs

is acepromazine a controlled drug?

no

what is the effect of acepromazine on cardiovascular system?

vasodilation and hypotension; may reduce cardiac output; these effects can be profound at higher doses

some patients are more sensitive to the effects of acepromazine and more likely to have prolonged recovery from acepromazine. which patients are most likely to be sensitive to acepromazine?

herding breeds, boxers, giant breeds, and any pt with a history of seizures

what is a potential complication of acepromazine administration in a breeding stallion?

penile prolapse and paraphimosis

what color is acepromazine when you draw it up in a syringe?

yellow

name 3 benzodiazepines?

diazepam, midazolam, zolazepam

how are they administered? what is the typical onset and duration of action? (benzos)

- IV or IM

- IV onset is rapid, IM onset 15 mins

- duration of 1-4 hrs or more

are these drugs controlled? (benzos)

yes (schedule IV, zolazepam schedule III)

which of these may be used as anticonvulsants?

diazepam and midazolam

what is the effect of these agents on the cardiovascular system? respiratory system? muscle tone? (benzos)

bradycardia, apnea, hypotension if given IV too rapidly; minimal resp depression; good muscle relaxation

do these agents have analgesic properties? (benzos)

no

diazepam is often used in combination with ketamine. what other drugs can it be mixed with?

nothing else

what drugs is zolazepam always mixed with?

tiletamine (in telazol)

identify 2 anticholinergic drugs. anticholinergics are also called para__________ because they ....

- glycopyrrolate, atropine

- parasympatholytics because they are antagonists of acetylcholine

are these controlled substances? what is the route of administration? (anticholinergics)

- no

- IV, IM, SQ

anticholinergics are often used as premeds for canine anesthetic protocols. what are their effects?

prevent bradycardia from vagal stimulation; reduce secretions- resp tract, tears

why are they not used routinely in equine and bovine anesthesia protocols? what is their potential adverse effect?

- because they inhibit intestinal peristalsis

- may cause colic in horses, bloat in ruminants