Lec 3: Neuro III (anesthesia)

anesthesia def

sedation of a pt for the purposes of a medical procedure/intervention

what are the diff types of anesthesia

• local

• general

• monitored anesthesia care (MAC)

localized anesthesia general def (use)

localized effect=loss of sensation in a focused body area or region (regional anesthesia) = nerve block

• local anesthetics used

• used for minor procedures ex sutures to a laceration

• used for some major procedures ex oral surgery, labor & delivery

general anesthesia def (use)

systemic effect=loss of consciousness

• combines many drugs for optimal effect

• used for major procedures ex abdominal surgery

Monitored anesthesia care (MAC) general def

systemic effect

• sedation at lower levels to maintain VS without intubation (ET tube)

• 3 types (level of sedation dependent): ex conscious sedation

  • =sleepy, able to awaken, able to respond when prompted, maintains VS without assistance

what is the drug class and MOA for local anesthesia

sodium channel blockers

• no Na influx into neurons=> no action potential => no cellular depolarization = no communication of sensory info to cerebral cortex

what areas are affected with local anesthesia

NS pathways affected: efferent & afferent

• sensory & motor

• drug specificity

what drugs are part of the sodium channel blockers for local anesthesia

• lidocaine

• prilocaine

• bupivacaine

• ropivacaine

what is the onset and duration of the sodium channel blockers for local anesthesia

onset=<2 min

• duration=drug dependent, dose dependent

• ex lidocaine & prilocaine = 1-2 hrs

• bupivacaine = 2-4 hrs

• ok for longer duration, allows for PO analgesia

what is cocaine’s drug class

sodium channel blocker (for local anesthesia)

• not commonly used

• high addiction risk

cocaine PKPD (distribution areas)

• local action ex intranasal route = nasal mucosa numbness

• CNS distribution=dopamine & reward system agonist

what routes do we use for local anesthesia

application near the procedure site

• topical=on the surface ex cream, spray

• infiltration=SC injection into the tissue near nerve ending

• nerve block=injection near a large nerve

what synergy drugs do we use for local anesthesia

• epinephrine (adrenalin)= localized vasoconstriction =bleeding control, increased DOA of anesthetic

• sodium bicarbonate=alkalization of the tissue in case of bacterial infection (bacterial acid)

• opioids, NSAIDS, tylenol=adjunct analgesia PRN, once anesthesia wears off

epidural local anesthesia route (what does it do/effects)

into epidural space

• location ensured by no CSF return in needle

• anesthetic bathes the spinal nerve

  • disruption of impulse transmission to/from CNS

  • assess sensory & motor ability (ex prior to mobilizing pt)

what locations can we do an epidural for local anesthetic (injection site or catheter placement at a specific location:)

• cervical

• thoracic

• lumbar

what is the onset of a local anesthesia epidural (route)

20-30 mins

• continuous infusion via an indwelling catheter

• drug dosage = higher for epidural route than for spinal route

Epidural catheter checks, where do we place it

• placement as per blue marks

• tip :10 cm

• :.15 cm

Local anesthesia: spinal “intrathecal” route (where is it done)

directly into CSF (intrathecal space/subarachnoid space)

• 1x dose injected

• always below L2 (avoids spinal cord damage)

  • needle position verification => CSF present in needle

  • quick onset

what alters the effect location for a spinal “intrathecal” route

• tonicity of solution effects location of action

• pt positioning effects location of action

what are the most common procedures done with the spinal “intrathecal” route

• abdominal

• pelvic

risk of resp depression if diaphragm affected

Side effects of anesthesia & nursing assessment

• monitor VS (RR!) esp. with spinal anesthesia=hypotension, resp depression

• test sensation & motor function, during & post

• site hematoma

• site infection

• catheter migration (epidural catheter)

• backache

• urinary retention (location of effect dependent)

• spinal cord injury

• wrongful CSF infiltration! (if epidural migrates into spinal, the dose is higher!)

general anesthesia def (SIMPLE DEF)

drug induced loss of consciousness, pts are not rousable even by painful stimulation

what are the tx goals of general anesthesia

• analgesia

• unconsciousness (& amnesia)

• loss of reflexes (procedure dependent)

what general anesthesia drugs do we use for analgesia

opioids, IV ex fentanyl, morphine

induction/maintenance def

• what general anesthesia drugs do we use for maintenance of unconsciousness (process of unconsciousness)

• induction=beginning of the loss of consciousness

• maintenance=of above for purpose of deep sedation aka surgical anesthesia

  • inhaled &/or IV general anesthetics

  • other ex benzodiazepines, ketamine

what general anesthesia drugs do we use for loss of reflexes

neuromuscular blocking agents, IV aka anticholinergics, paralytics

Inhaled general anesthetics drugs and MOA

nitrous oxide, halothane, isoflurane

• decrease action potentials, increase GABA, other CNS effects

list Intravenous anesthetics drug and MOA

barbiturate-like drug=propofol (diprivan)

• increases GABA, other unknown CNS effects

• rapid onset of action

• short t1/2, continuous infusion for effect

• dose dependent: intubation necessary, VS support (ex hypotension)

what drug class do we use as neuromuscular blocking agents and their MOA

anticholinergics

• block Ach binding at nicotinic receptors (SNS, PNS, Somatic)

• =no BBB penetration

• =muscle paralysis, including diaphragm (paralytics, ventilation required)

• ideal for complex procedures

• rapid onset, continuous IV infusion

list the neuromuscular blocking drugs (anticholinergics)

• vecuronium

• rocuronium

• pancuronium

• succinylcholine (short t1/2)

MAC def

combo of sedative & analgesic meds used to induce a depression of consciousness, while able to maintain an airway & be awakened

• conscious sedation

what drugs do we use for MAC

• ketamine (note: higher doses than for depression tx)

• benzodiazepine ex midazolam (Versed)

• adjunct meds= opioids

CNS drugs – cautions, things to keep in mind

• do not consume with other CNS drugs ex ETOH

  • drug-drug interactions

  • additive effects

  • risk of toxicity

• assess for effect, titrate dose PRN

• evaluate if CNS effects/side effects seriously interfere with ADLs

• risk of addiction

• risk of overdose

physical dependence on a drug def and effects

• body adapts to the presence of a drug

• creates tolerance (requiring higher doses to yield the same effect)

• creates withdrawal symptoms if abruptly stopped (2-4 weeks duration)

• withdrawal weaning protocols carefully observed

what SNS effects/withdrawal symptoms occur when physical dependence is in play

• VS changes

• blurred vision

• loss of appetite

what other effects/withdrawal symptoms occur when physical dependence is in play

• fever

• psychosis, agitation, anxiety, panic

• seizures

• disorientation, impaired memory & focus

what must occur do be diagnosed with drug Abuse & Psychological Dependence according to the DSM-5

3 or more, occurring at any time in the same 12 month period:

• spending a great deal of time acquiring, using and recovering from use of the substance

• disruption of important activities because of substance use

• using more than intended

• compulsive use despite harm

• unsuccessful efforts to cut down

• tolerance=requiring more drug over time

• withdrawal symptoms if without drug (note: physical dependence is present)