General anesthetics, local anesthetics, and muscle relaxants Flashcards
Why would general anesthetics be used rather than local?
used for more extensive surgeries/procedures bc the pt is unconscious
What are the 7 things an anesthetic agent must be able to do?
Rapid onset of anesthesia (loss of consciousness and sensation)
Skeletal muscle relaxation (this goal is met by using a skeletal mm blocker with a general anesthetic)
Inhibition of sensory and autonomic reflexes
Easy adjustment of the anesthetic dosage during the procedure
A minimum of toxic side effects
Rapid, uneventful recovery after the drug is stopped
Amnesia (no recollection of what happened during surgery)
If a patient is losing sensation, but is still aware of what is happening, what stage of general anesthesia are they?
1
If a patient is unconscious, but they are restless and agitated, what stage of general anesthesia are they?
2
What is the most desirable stage of general anesthesia for surgery?
3 (want to get pt here as quick as possible & stay)
What is another name for stage 4 of general anesthesia and what are the side effects?
Medullary paralysis – deep – cessation of spontaneous respiration because respiratory control centers are inhibited. BP regulation is affected, cardiovascular collapse can occur. If this stage is reached respiratory and circulatory support must be provided or patient can die
In what ways can a general anesthesia be administrated?
intravenous, inhaled, IV
What is a pro & con of having inhaled general anesthetic?
doses can easily be adjusted based on how patient is responding, but causes increased length of time required for onset
what drug specifically is good for short procedures with rapid recovery so able to mobilize quickly?
Proposal (diprivan)
_____ drug typically given first to get the patient to stage 3 of general anesthetic and _____ is used to keep a pt there during a procedure
IV & inhaled
What is the ONLY inhaled general anesthetic
nitrous oxide
The pharmokinetics of general anesthetics results in the possibility of the drugs being stored where and what is the effect of that?
Anesthetics may become stored in adipose tissue and then will be re-released or washed out as the patient recovers from surgery – this can cause confusion, disorientation, lethargy
How do general anesthetic work?
Decrease activity of neurons in the reticular activating system in the brain which causes sedation, hypnosis, and amnesia
Inhibit neuronal function in the spinal cord which causes immobility and inhibits responses to pain (such as surgery incisions)
Bind to specific receptors located on the outer surface of the CNS neurons enhancing CNS inhibition
what are the 2 types of adjuvants (related to general anesthetics)
preoperative meds & neuromuscular blockers
Why might a patient be given preoperative medications (general anesthetics) and what are some examples?
Helps to relax the patient and reduce anxiety before getting to the OR
Examples: Barbiturates, benzodiazepines, opioids
Why might a patient be given neuromuscular blockers in addition to general anesthetics?
In order to ensure skeletal mm paralysis neuromuscular blockers and requires smaller dose of general anesthetics
How do NM blockers work?
Work by blocking the postsynaptic acetylcholine receptor located at the skeletal neuromuscular junction
Your patient had a neuromuscular blocker during surgery. What is something that a PT should be aware of?
residual effects of neuromuscular blockers can persist after surgery, including residual paralysis, skeletal muscle contractions remain depressed for several hours
What is a side effect of general anesthetics that a PT should be worried about and how should it be addressed?
Bronchial secretions may accumulate in the lungs in patients recovering from general anesthesia due to suppressed recovering from general anesthesia due to suppressed mucociliary clearance which can lead to infections
PTs should address this through early mobilization and breathing exercises or postural drainage
What population is at greatest risk for detrimental effects on memory, attention and cognition following surgery?
Most prevalent in older adults who had some cognitive decline before surgery
The degree of this is related to the type of anesthesia used, how long it was administered and how deeply the patient was sedated
Why would local anesthetics be used vs general?
used when the surgery area is a small, defined area, used when the patient needs to remain conscious during surgery
What is the primary disadvantage of local anesthetics?
length of time required to establish an anesthetic effect and the risk that it could be incomplete
What is the goal of local anesthetics?
to block afferent nerve transmission along the peripheral nerve so that a procedure is painless
T/F: An epidural is an example of a local anesthetic?
True: Can be introduced at the spinal cord and the transmission of impulses at a specific level of the cord may be blocked
What are the dangers of a local anesthetic reaching the circulatory system?
confusion, agitation, excitation, seizures, decreased cardiac excitation, heart rate, and force of contractions
When might a topical local anesthetic be used?
Used to reduce pain prior to minor surgical procedure (wound cleaning, circumcision, cataract surgery)
When might a transdermal local anesthetic be used?
Can treat localized musculoskeletal pain – OA, LBP, fractures, and neuropathic pain
When might a peripheral nerve block local anesthetic be used?
Common in dental procedures and in surgeries for the foot and hand, but can be used near near larger nerves (sciatic) or around a plexus (brachial plexus) anesthetize a larger area of UE or LE (Common after joint replacements, ligament reconstruction, and other orthopedic surgeries)
When might a central neuronal blockade (local anesthetic) be used?
used whenever analgesia is needed for a large region: common during obstetrics and chronic pain relief
When might a sympathetic blockade (local anesthetic) be used?
Useful with diseases such as complex regional pain syndrome as it reduces excessive sympathetic outflow to an affected extremity
How do local anesthetics work?
inhibit the opening of sodium channels located on nerve membranes which blocks action potential progression along a nerve axon
What are important side effects that you should be aware of during PT with anesthetics?
- don’t put modalities on transdermal patch
- if pt has continuous nerve block be aware that if you are exercising a joint the patient will not feel pain if you over stress the joint tissues
- patient receiving local anesthetic injections for treatment of chronic pain schedule the rehab immediately after each injection
-central nerve blockade sensation may be diminished below so check sensation & strength before ambulating & be careful with STIM
Why might a patient be taking skeletal muscle relaxants and what is their goal?
treat conditions where there is hyper-excitable skeletal muscles: spasticity and muscle spasms
to normalize muscle excitability without a decrease in muscle function
T/F diazepam & centrally acting anti-spasm drugs are both antispasm drugs
True
Which anti-spasm drug is most applicable for short term management due to its tolerance and dependence, withdrawal after prolonged used which can cause seizures, anxiety, and agitation
diazepam and centrally acting anti-spasm drugs
How does diazepam reduce spasticity
Increases the inhibitory effects of GABA on alpha motor neuron activity in the spinal cord
Centrally acting anti-spasm drugs reduce spasticity by what possibilities?
By inhibiting the neurons in the polysynaptic pathways these drugs could decrease alpha motor neuron excitability and cause relaxation of skeletal mm or sedation of the CNS
What is most effective: Baclofen or intrathecal baclofen & why?
Baclofen intrathecal because its injected directly into the subarachnoid space at a specific SC level & can have smaller doses due to injection site
Which drug has less side effects and why? Baclofen or intrathecal baclofen?
intrathecal baclofen because the drug stays in the area injected and there is less chance it gets into systemic circulation
T/F: There is a small window between baclofen that reduces spasticity and when it begins to inhibit voluntary motor function
True
What is the only mm relaxant that effects skeletal muscle cell directly thus is used to treat severe spasticity but not spasms
Dantrolene Sodium
What drug is this based on the facts below:
OG developed as an anti-seizure drug
Trade name is Neurontin
Decreases spasticity associated with SCI and MS
Also used to treat neuropathic pain
Side effects: sedation, fatigue, dizziness, and ataxia
Gabapentin
Why might a doctor prescribe tizandine for muscle spasm rather than baclofen or those alike?
has milder side effects and less mm weakness so would be better to maintain adequate strength for functional movements
T/F Tizandine is used following both acute brain injury and cerebral lesions
False: It might slow the recovery of an acute brain injury
What form of botulinum toxin is most commonly used & what is it common name?
Type A: Botox
How does botulinum toxin work?
Decreases mm excitation by disrupting synaptic transmission at the neuromuscular junction creating control over localized hyper-excitability
How often would a patient need to get botox injections?
Within 3 months as sx return
Why can only 1-2 mm be injected with botox?
it can become toxic
What conditions can botox be used for?
reduce spasticity in specific mm due to CP, TBI, CVA, and SCI
Injecting it into the bladder detrusor mm can help those with stress urinary incontinence
Also used to treat those with chronic pain syndrome, migraines, neuropathic pain
What are the goals of therapy when it comes to a patient on muscle relaxant drugs?
PT should perform aggressive therapy when drugs have created decrease in spasticity so that optimal motor function can be achieved so drugs can be discontinued as quickly as possible.
