Part 4 - Anesthesia Flashcards
Types of Anesthesia
General Anesthetics
Local Anesthetics
General Anesthesia Goal
Absence of all perceived sensations
General Anesthesia Purpose
Allow detailed surgical procedures, etc with minimal harm to patient
General Anesthesia Requirements
Loss of consciousness; perceived sensations Amnesia Inhibition of reflexes Skeletal Muscle Relaxation Safe, transient, predictable
Stages of General Anesthesia
- Analgesia
- Excitement/delirium
- Surgical Anesthesia
- Medullary paralysis
Types of general anesthetics
Inhalation agents
IV agents
Inhalation agents
Halogenated liquids
Nitrous Oxide
Other gases
IV agents
Barbiturates
Benzodiazepines
Opioids
Choice of anesthetic
Often use 2 or more agents to provide balanced anesthesia
Traditionally injected followed by inhaled
General Anesthetic MOA
Increase inhibition or decrease excitation throughout the CNS by:
- Direct effect on lipid bilayer
- Direct effect on neuronal receptors
- Combination of lipid and receptor effect
Anesthetic Adjuvants
Given with or before anesthesia
- Relax and sedate patient prior to sx
- Reduce post-op nausea and vomiting
- Reduce other problems related to anesthesia
Neuromuscular Junction Blockers
Used to paralyze skeletal muscle to facilitate positioning on table, prevent spasms, allow easier mechanical ventilation
- Depolarizing blocker: doesn’t let ACh receptor recover
- Nondepolarizing blocker: Don’t let ACh bind
NMJ Blockers effects
Short duration of action
Some patients may lack metabolizing enzymes; pt remains paralyzed at end of sx
Effects can be reverse by cholinesterase inhibitors or inactivating drugs
These drugs don’t cause anesthesia, so anesthesia could wear off
Dissociative Anesthesia
Patient may remain conscious but indifferent to surrounding
Achieved by use of ketamine or combination of antipsychotic with opioid
Useful in diagnostic/radiologic procedures, dressing changes, emergency surgeries
General Anesthetic Rehabilitation concerns
Use in burn debridement, dressing changes Dealing with residual effects -Respiratory hygiene -Short-term confusion, lethargy -Possible long term effects on cognition
Local Anesthesia Goal
Interrupt nerve conduction at site of application
Local Anesthesia Purpose
Prevent or relieve pain without LOC or systemic effects
Typical local anesthetics
“-caine”; lidocaine, procaine, bupivacaine
Local Anesthetics MOA
Bind to sodium channels in nerve membrane
Inactivate Na channel; prevent action potential conduction
Clinical Use and Administration
Topical Transdermal Infiltration Nerve Block Spinal Block Sympathetic Block Intravenous regional anesthesia
Topical Administration
Applied to surface of skin
Pain, relief, minor burns, abrasions
Also used prior to injections, IV insertion
Use in spasticity?
Transdermal Administration
Movement through skin by electricity or ultrasound
Also use patches
Infiltration
Injecting drug subcutaneously
Allowed to penetrate selected area
Commonly used before suturing wound
Peripheral Nerve Block
Injected close to nerve or nerve plexus
Commonly used for dental procedures, other minor surgeries
Spinal/Epidural Block
Epidural: Administration outside of dura
Spinal: Administration into subarachnoid space
Sympathetic Block
Drug injected around sympathetic chain ganglia
Intravenous Regional Anesthesia (Bier Block)
Local anesthesia injected into venous system
Tourniquet placed proximally
Used for some surgical procedures or to treat CRPS/RSDS
Continuous Nerve Block
Small catheter implanted near peripheral nerve to a specific region
Local Anesthetic dripped slowly onto nerve
Excellent post op pain control
Differential Nerve Block
Smallest, unmyelinated fibers affected first
Largest myelinated fibers affected last
Differential Nerve Block order of functional loss
- Pain
- Temperature
- Touch
- Proprioceptive
- Motor
Local anesthetics implications for rehab
Transdermal application especially
Be aware for possible absorption into systemic circulation
Local Anesthetic Systemic Toxicity CNS effects
Tinnitus
Agitation, restlessness, seizures
Decreased sensation in tongue and mouth
Later stages lead to CNS depression
LAST Cardiotoxicity
Changes in heart rate (Bradycardia)
Other ECG abnormalities
Clinical signs of cardiac depression
Cardiac arrest
