Anesthesia Flashcards
What are the 3 types of anesthesia?
- General
- Regional
- Local
What is general anesthesia?
- Administration of anesthesia to the point of unconsciousness
- Used for extensive surgical procedures
What is regional anesthesia?
- Administration of anesthesia to the point where the patient remains conscious
- Used when a physician needs to anesthetize a specific region of the body
What is local anesthesia?
- Administration of anesthesia where the patient remains conscious
- Used when a physician is doing a surgery to a small, well-defined area
Is general anesthesia a reversible or nonreversible state of unconsciousness?
Reversible
Upon awakening from anesthesia does the patient have recollection of what occured?
No
The ideal anesthetic agent must be able to do what 7 things?
- Rapid onset of LOC (loss of consciousness) and sensation)
- Skeletal muscle relaxation
- Inhibition of sensory and autonomic reflexes
- Easy adjustment of anesthetic dosage during procedure
- Minimum of toxic side effects (I.e must be safe)
- Rapid, uneventful recovery after anesthesia is terminated
- Amnesia: no recollection of what occurred during surgery
What is stage 1 of general anesthesia induction?
Analgesia: begins to lose somatic sensation but still conscious and somewhat aware
What is stage 2 of general anesthesia induction?
Excitement (Delirium): Unconscious but may be agitated and restless. Need to move quickly through this
What is stage 3 of general anesthesia induction?
Surgical Anesthesia: Level desirable for surgical procedure. Onset of regular, deep respiration
What is stage 4 of general anesthesia induction?
Medullary Paralysis: Cessation of spontaneous respiration. Respiratory and circulatory support must be provided.
What is the anesthetic goal when it comes to the stages?
Bring patient to stage 3 as rapidly as possible and maintain there during the surgery
What are the pros and cons of IV anesthetics?
- Pro: rapid onset with quick move to stage 3
- Con: lack of control over dosage
What are the pros and cons of inhalation anesthetics?
- Pro: easier method of making dosage adjustments
- Con: longer time for onset of stage 3
Why would we use a combination of IV and inhalation anesthetics?
- IV is used to 1st rapidly induce anesthesia
- Inhalation is used to maintain the anesthesia
- Combination provides optimal anesthesia with minimal
What are examples of IV anesthetics?
- Ketamine
- Thiopental
- Propofol
- Fentanyl
- Remifentanil
- Midazolam
- Opioids
What are examples of inhalation anesthetics?
- Halothane
- Sevoflurane
- Desflurane
- Isoflurane
- Enflurane
What are the 5 different IV anesthetic drug categories?
- Barbiturates (ex: thiopental)
- Dissociative (ex: ketamine)
- Miscellaneous (ex: etomidate, propofol)
- Opioids (ex: fentanyl)
- Benzodiazepines (ex: midazolam)
What are the 2 different inhalation anesthetic drug categories?
- Gas (ex: nitrous oxide)
- Volatile Liquids (ex: halothane)
What is the mechanism of action of anesthesia?
- Target ligand gated ion channels
- GABA receptor gated chloride channels are the most important sites and they cause an inhibitory action
Anesthesia is highly lipid soluble and goes through the lipid bilayer cell membrane. Because of this what may cause someone to wake up slower from anesthesia than someone else?
Widely and uniformly distributed throughout the body and temporarily stored in the adipose tissue. It is slowly washed out during recovery and may take hours to days to depleted fully and can lead to confusion, disorientation, and lethargy as the drug is redistributed, especially if the pt is overweight or older.
What is the goal of regional anesthetics?
Produce loss of sensation and/or motor function in a specific extremity or area of the body
Regional anesthetics provide selective analgesia and muscle relaxation without affecting what?
The patients protective reflexes or altering cognitive abilities
Regional anesthetics and be used along with or in conjunction with what?
General anesthesia
Regional anesthetics alter _____ channel activity.
Na (sodium)
What are the advantages of regional anesthesia?
- May provide postoperative analgesia
- Decreases stress response to anesthesia
- Safer, no endotracheal intubation needed
- Decreased anesthesia side effects
What are the disadvantages of regional anesthesia?
- Not always practical (ex: abdominal surgery)
- Takes more time
- Requires patient cooperation
- Limited duration of action
- Potential nerve damage
What do the typical local anesthetics end in?
“caine”
- Lidocaine
- Benzocaine
- Etidocaine
What are the 6 different types of regional anesthesia?
- Topical
- Local
- Intravenous Regional
- Peripheral Nerve Blockade
- Sympathetic Blockade
- Central Blockade (Neuraxial blocks - Spinal and Epidural)
What is a topical regional anesthetic?
- Applied directly to the skin or mucous membrane
- Short duration: skin: 30-60 minutes
What is a local regional anesthetic?
- Local anesthetic injected directly into the tissue
- Produces a sensory blockade in specific area
- Contains epinephrine which may cause excess vasoconstriction
What is a IV regional anesthetic?
- Local anesthetic via IV to a specific extremity after use of occluding tourniquet
- Rapid onset of sensory blockade, profound muscle relaxation
- Very short acting due to limitations of tourniquet application
What is a peripheral nerve blockade regional anesthetic?
- Injection of local anesthetic around a specific nerve or plexus to provide sensory and/ or motor blockade (ex: total knee)
- Rapid onset
What is a sympathetic blockade regional anesthetic?
- Local anesthetic injected around sympathetic nerves or ganglions
- Provides pain relief for chronic pain syndromes
What are the two different types of central blockade regional anesthetics?
- Spinal anesthesia (subarachnoid or intrathecal block)
- Epidural
What is a spinal anesthesia (subarachnoid or intrathecal block)?
- Anesthetic solution (local +opioid) mixes with CSF and acts directly on the nerve root or spinal cord
- Done below L2 to avoid SCI
What is an epidural?
- Interrupts transmission of pain impulses along the spinal nerve roots
- May cause sensory and motor blockade, but lower doses allow motor function to remain intact
- Can be given as a single injection, repeat, or continuous infusion via catheter
What are complications of regional anesthetics?
- Similar rate as with general anesthesia
- Central nervous system toxicity can lead to seizures
- Cardiac toxicity can lead to cardiac arrest
- Local tissue toxicity can lead to nerve injury, hypoxic injury, or spinal cord injury
