1. Introduction Flashcards
What does it mean for anesthesia to be partial?
Local anesthesia
What are some quick facts about anesthesia to be aware about?
It is loss of feeling or sensation (including pain), it is partial or complete
We are intentionally inducing them
Used to perform surgery oro there painful surgeries
it is reversible,
can be local, regional or general
What is local anesthesia?
loss of feeling or sensation to a specific area due to local desensitization of a peripheral nerve bed
“freezing” line blocks
What is regional anesthesia
loss of feeling or sensation to a portion of the body (limb, abdomen)
Due to desensitization of spinal nerves and/or peripheral nerve bundles
Spinal block, epidural
What is general anesthesia?
Anesthesia due to depression of the CNS
A coma-like state that affects the entire body
Patient neither perceives nor recalls noxious stimuli
Inc risk of adverse effects
What is tranquilization?
Reduces anxiety and produces sense of tranquility.
Anti-anxiety, calm, chillout
Reduces the ability to respond to a stimulus
there is no change in the ability to perceive pain
WHat is sedation?
More profound than transquilization and prods drawsiness and/or hypnosis
The sedatives reduce anxiety, reduce the ability to respond to a stimulus
sedatives also decrease sensation of pain
Animal is CONSCIOUS
3 lvls - light, moderate, heavy sedation
What is surgical anesthesia?
The state of which there is no perception of pain, significant CNS and patient is unconscious
What is the definition of analgesia?
relief of pain without loss of consciousness
What is an analgesic def?
A drug that relieves pain
What is balanced anesthesia?
AKA multimodal anesthesia/analgesia
1. Using multiple drugs in combination
2. In smaller doses than if only using one drug on its own
3. to obtain appropriate CNS depression to perform a specific procedure
Includes: premeds, induction agent, maintenance anesthetic, analgesics (pre- and intra- operative)
What is the benefits of balances anesthesia?
Limits adverse effects of each individual drug
Maximizes the benefits of each drug
Accounts for motor, sensory (PAIN), reflex and mental aspects of the nervous system
What is an example of a balances anesthesia?
Protocol vs drug
Anti-anxiety/emetic = acepromazine
Sedation, pre-emptive analgesia: hydromorphone
Anticholinergic: atropine
Induction: Alfaxalone
Maintenance anesthetic: isoflurane
Epidural: lidocaine, bupivacaine, morphine
Perio-operative analgesia: meloxicam
What must a anesthetic protocol take into account?
The patient, procedure and facilities available
They will constantly change btw patients, and even for the same patient
What is the RVT’s role in anesthesia?
Planning, patient assessment, pre-medication, surgical fluids, induction, surgical prep, maintenance anesthesia, recover (period btw when anesthetic drug is removed and vitals return to normal, animal is conscious), post-operative analgesia
In regards to the RVT’s role, what might we need to plan before going under anesthesia?
Patient - estimates, required diagnostics, pre-surg medications
organizing with owner (incl fasting req’s)
consent
Equipment and materials - drugs, anesthetic equipment, surgical equipment
In regards to the RVT’s role, what might we need to assess on our patient before going under
weight, TPR, assess for pre-procedure mentation and pain
any pre-anesthetic dx’s (blood, rads)
In regards to the RVT’s role, what might we need for pre-meds before going under?
Calculating dosages, administering medications
assessing degree of sedation after administration
responding to adverse reaction to sedation/pre-med
In regards to the RVT’s role, what might we need for surgical fluids before going under?
setting up surgical fluids
catheter placement
calculating fluid rates based onf fluid plan
In regards to the RVT’s role, what might we need to induce before going under?
calculating and administering injectable anesthetic dose
endotracheal intubation
assessing depth of anesthesia
patient monitoring
In regards to the RVT’s role, what might we need to know for maintenance anesthesia before going under?
Operating anesthetic machines for oxygenation and delivery of inhalant drugs
Ensuring fluids and thermosupport
Patient assessment for depth of anesthesia and patient vitals
Monitoring and responding to drug effects; ability to rapidly respond in the case of overdose/arrest
differentiating from pain from other stress
In regards to the RVT’s role, what might we need to know during the recovery period of anesthesia?
patient monitoring and assessment
extubation, assessing for pain/other physiological stress
requesting appropriate analgesia/sedation if indicated
providing non-pharmacological comfort and care
In regards to the RVT’s role, what might we need for post-operative analgesia for anesthesia
patient monitoring
assessing for pain and comfort
calculating and administering analgesics and ancillary support (ex, PT, IV fluids, antibiotics, nutrition)
What are some fundamental challenges and inherent risks of anesthesia?
Very narrow therapeutic index - consequences of a calculation or administration error
Vital signs and indications of anesthetic depth (must be closely monitored)
Accurate interpretation of visual, tactile, and auditory info from patient, anesthetic equipment and monitoring devices
comprehensive understanding of the significance of physical parameters (HR, RR, reflexes) and machine generated data (BP, O2 sat’n)
Potential for patient harm during administration of anesthetics is relatively high
competence and confidence are earned thru study, practice, persistence, caring attitude, dedication to excellence
What is essential to know about anesthesia?
the pharmacology of common drugs (effects, side effects (expected vs not)
Pharmacy laws (controlled drugs)
dose calculations
Normal patient physiology (not normal is automatically abnormal, and what normal changes are under anesthesia)
how to recognize and respond to adverse effects
What must be done as a pre-anesthetic assessment?
Patient hx - signalment, current/past illness’, meds currently administered, allergies or drug reactions, status of preventive care
PE
Hematology/biochemistry
anesthetic plan
What does an entire anesthetic protocol include?
pre-anesthetic tx, premeds, induction, maintenance, analgesia, blocks, emergency drugs, monitoring/special equipment, recovery/post-procedure analgesia plan
What is a neuron?
a basic functional unit of the nervous system. Composted of a cell body, dendrites and an axon. Initiate nerve impulses, and also conduct them
What is a neurotransmitters
Chemical released by the presynaptic neuron that diffuses across the synaptic clef, binds with the receptor on the post synaptic membrane, and stimulates or inhibits the postsynaptic return
What is a synapse?
Junction btw two neurons or btw a neuron and target cell
What is a receptor in the nervous system?
A specialized protein to which neurotransmitters bind “lock and key”
What is a nerve impulse?
Wave of cell membrane depolarization that travels from the point of stimulus down the length of a nerve cell process
Conducted along a nerve fibre by the “flipping” of a electrical charges across the cell membrane (depolarization), followed quickly by “unflipping” of the electrical charges (repolarization)
How might local anesthetics affect the nervous system
Drugs injected to block the conduction of sensations.
Ex lidocaine which prevents sensory nerves from depolarizing despite stimulation
How do epidural anesthetia affect the nervous system?
anesthetic agents injected into the space outside the spinal cord dura mater to prod lg areas of local anesthesia
They block depolarization waves thru spinal nerves thus removing perception of pain from body they supply
Body more readily maintain autonomic func
What are the 3 types of neurotransmitters?
Excitatory - have an excitatory effect on the postsynaptic membrane when combined with the receptor
Inhibitory - tend to depress or decrease depolarization of other neurons or target issues
Both
Ex. acetylcholine, catecholamines, GABA, glycine
What is the somatic nervous system?
Conscious or voluntary control of skeletal muscles
What is the autonomic nervous system?
Sympathetic nervous system
Parasympathetic nervous system
What is the sympathetic nervous system?
fight or flight
neurotransmitter: catecholamines; primarily norepinephrine, epinephrine and dopamine
Adrenic neurons like alpha 1 (found on blood vessels, and cause vasoconstriction of the skin, GI tract and kidney)
Beta 1: increase in HR and force of contraction
Beta2: bronchodilation
What is the parasympathetic nervous system
rest and restore
neurotransmitter: acetylcholine
cholinergin neurons like nicotinic and muscarinic
Define anesthetic agent?
Any drug to induce a loss of sensation with or w/o unconsciousness
What is an adjunct definition?
A drug that is not a true anesthetic, but is used during anesthesia to prod other desired effects
Ex. sedation, muscle relaxation, analgesia, reversal, neuromuscular blockade, or parasymp blockage
How are anesthetic agents classified?
route - inhalent, injectable, oral
Time period of administration - pre-anes meds, induction/maint. agents
Principal effect - local/general anes, sedatives, tranquilizers, muscle relaxants, neuromuscular blockers, anticholinergic agents, reversal agents
CHEMISTRY OF THE DRUG
Are are the classifications of drugs based on their chemistry?
anticholinergics
sedatives/tranquilizers (phenothiazines, benzodiazepines, alpha2-agonists)
opiods, propofol
Etomidate, alfaxalone, barbiturates
dissociatives, guaifenesin, inhalent anesthetics
What do agonists do?
bind to and stimulate tissue receptors
The same activity as naturally occurring neurotransmitters
Bind to and “turn on”; effect if to inc naturally occurring response
What do antagonists do?
bind to, but do NOT stimulate receptors
reversals - competitively bind to receptors and displace the corresponding agonist, blocking further action
Most commonly act by binding to receptors and blocking neurotransmitters from binding (blocking the “on” switch)
What are partial agonists?
bind to and partially stimulate receptors
What are agonist-antagonists?
bind to more than one receptor type and simultaneously stimulate one or block at least one
How do anesthetic drugs work?
- mimicking inhibitory neurotransmitters that turn down nerve function (turning on the off signals)
OR 2. can bind to and block the action of the naturally occurring neurotransmitters - blocking the on signals
What are nerve depressants?
all the drugs in general anesthesia are nerve depressents, meaning
General anes depress CNS function, especially the brain
Regional anes directed @ peripheral nerve bundles and/or spinal segments
Local anes block peripheral nerves
tranquilizers and sedatives depress CNS func to a lesser degree
What are CNS depressants?
Central acting drugs
tranquilizers, sedatives and general anesthetics
act directly on the brain which creates wide ranging effects that also affect the autonomic NS
Has a low therapeutic index
All have ability to cause death
Tranquilization-sedation-narcosis/hypnosis-loss of consciousness-brainstem shut-down- death
What is the effects of drugs on the autonomic nervous system>
Drugs may influence ANS
may be direct side-effect of drug
part o turning on the parasymp response
Especially sedatives and tranquilizers
effects of turning up the PS response = dec RR, bronchoconstriction
peripheral vasodilated, dec HR and stroke volume
Inc bronchiolar and GI secretions, miosis (constriction)
Question! Patient is administered DRUG A. Drug causes sedation. Side effect is it turns up the parasymp response. List 5 changes in the patient that might occur that would indicate to you that the drug is working. List 2 physiological changes would occur in the event of an overdose
Decreased HR, bronchoconstriction, miosis, increased GI motility, secretions, salivation and blood flow
