Transcript ANESTHESIA Part I

Mong Lam, CRNA
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History
Basic concepts
Types of anesthesia
Anesthesia machine
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Horace Wells and nitrous oxide
William Thomas Green Morton and ether
Ether Dome
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Certified Registered Nurse Anesthetist (CRNA)
Anesthesiologist (MD)
Anesthesia model or practice setting
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Types of anesthesia
Concepts
Administration & Selection
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Definition: “Lack of Sensation”
Describes a process that is used to alleviate
pain and suffering during a surgical
procedure
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Achieved If All Of The Following Are Met:
Hypnosis
Anesthesia
Amnesia
Muscle Relaxation
Optimal Positioning of Patient
Homeostasis of Vital Functions
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Altered state of consciousness related to how
the patient perceives his or her environment
(surgical) and procedure (surgical)
Induce sleep
Can be light to fully unconscious
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Lack of sensation
Allows for “pain-free” surgery
Ranges from topical, local, regional and
general (systemic) agents
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Lack of recall of surgical events
Allows for more cooperative relaxed patient
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Combined with inhalation (gases) agents to
produce muscle relaxation to total paralysis
Allows for endotracheal intubation
Facilitates exposure of tissues and organs as
muscles are in a relaxed state
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Allows for surgical site exposure/access
Allows for monitoring of the surgical patient
Allows/provides physiological homeostasis
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Maintenance of the patient’s physiological
status until surgical intervention is complete
Most dangerous part of surgery is anesthesia
Are inducing a state close to death without
crossing that line
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Determining the Right Anesthetic
Patient’s age, weight, and build
Emotional, psychological and physical needs
Type of operation and duration of operation
Lab and X-ray findings
Pre-existing illnesses or diseases
Medications on
Allergies
History of drug or alcohol abuse
Time since last ingested food, particularly with
emergencies
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Based on the evaluation/assessment done
preoperatively, the patient is assigned a Class
# 1 through #6. This determines what kind
of risk is involved for the patient for the
surgical procedure about to be performed.
Class 1- Patient has no previous/current
physical or mental medical history
Class 2- Mild to moderate disease
present (controlled HTN, asthma,
controlled diabetes, mildly obese,
anemic, tobacco use) with no functional
limitations
Class 3- severe disease present
(controlled angina, has had a myocardial
infarction, HTN that is not controlled,
respiratory disease that is causing difficulties
presently, greatly obese) with functional
limitations
Class 4- severe disease (s) present that are
life-threatening (unstable angina, CHF,
respiratory disease that is
debilitating, liver failure, kidney failure,
myocardial infarction)
Class 5- Moribound patient who is not
expected to survive with or without surgery
Class 6- Is brain dead/life support is
being provided .This is an organ harvest or
procurement.
(E) Emergency Modifier- an E is added
to the Class # in cases of emergency
surgery
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Patient safety
Optimal results
3 types:
1. General
 Focus on altering state of
consciousness, awareness and pain
perception
2. Nerve Conduction Blockade
 Focus on preventing sensory nerve impulse
transmission
3. MAC (monitored anesthesia care)
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Combined to deliver “Balanced Anesthesia”
Inhalation agents
Intravenous agents
Less Common:
Intramuscular agents
Instillation
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Amnesia
Analgesia
Anesthesia
Muscle Relaxation
Together provide “Balanced Anesthesia”
I. Amnesia stage is lightest stage that begins with administration of
agent ends with loss of consciousness
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Good stage for MAC
II. Excitement or Delirium stage from loss of consciousness to loss of
eyelid reflex and regular breathing
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Patient movements are uninhibited
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Might see vomiting, laryngospasm, hypertension, tachycardia
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Rarely seen except in children due to drugs that are available
now to carry patients straight to stage III
III. Surgical anesthesia stage from regular breathing and loss of eyelid
reflex to cessation of breathing
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Patient unresponsive and hearing is last to go
IV. Overdose stage dilated nonreactive pupils, cessation of breathing,
hypotension can quickly lead to circulatory arrest if uncorrected
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Autonomic response is totally blocked to all stimuli
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Preinduction begins with premed administered
and ends when anesthesia induction begins in OR
Induction from consciousness to unconsciousness
Maintenance surgery takes place during this
requires maintenance of physiological function by
anesthetist
Emergence as surgery is completed (start to wake
up), restoration of gag reflex, extubation
Recovery time during when patient returns to full
consciousness begins in OR and carries into stay
in PACU and beginning healing stages
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GA vs MAC
GA vs block
Types of surgery and length
Age and mental status
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Inhalation Agents:
Nitrous Oxide (N²O)
Ethrane (Enflurane)
Forane (Isoflurane)
Halothane (Fluothane)
Sevoflurane (Sevoflurane)
Suprane (Desflurane)
Intravenous Agents:
1. Barbiturates
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Short acting
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Anesthesia
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Not analgesic
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Pentothal (thiopental)
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Brevital (Methohexital)
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Benzodiazepines
Sedative and amnesiac effects
Versed (Midazolam)
Valium (Diazepam)
Ativan (Lorazepam)
3.
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Individual Agent
Propofol (Diprivan)
Sedative/Hypnotic
Anesthetic
Amnesiac
No Analgesia
No Muscle Relaxation
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Narcotics
Maintenance of general anesthesia
Anesthetic
Sublimaze (Fentanyl)
Alfenta (Alfentanil)
Sufenta (Sufentanil)
Morphine (Morphine Sulfate)
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Muscle Relaxants (neuromuscular blocking
agents)
To receive endotracheal intubation, patient must
be paralyzed or have relaxed muscles
a. Depolarizing Agents: Initiate
contractions called fasciculation
example: Succinylcholine (Anectine)
b. Nondepolarizing Agents: Prevent
contractions
examples: Curare, Pavulon, Norcuron
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Includes:
Topical anesthesia
Local anesthesia
Regional anesthesia
Spinal (intrathecal) block
Epidural block
Caudal block
Nerve plexus block
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Used on mucous membranes: upper
aerodigestive tract, urethra, rectum, and
skin
Cryoanesthesia reduces nerve conduction
by localized freezing with a probe
connected to a cryoprecipitate unit that
uses nitrogen
Cryoanesthesia can also be performed with
ice
Lidocaine jelly
Cocaine (topical only!) Most common use:
sinus surgery
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Immediate surgical site anesthesia
Affects small circumscribed area
Can be injected or applied topically
Lidocaine (Xylocaine)
Bupivicaine (Marcaine, Sensorcaine)
Procaine (Novocain)
Tetracaine (Pontocaine)
Mepivacaine (Carbocaine)
Hyaluronidase (Wydase) facilitator/enhancer of above
medications’ effects
Epinephrine (Adrenalin) additive to above for vasoconstrictive
properties
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Combination of nerve conduction blockade
on topical or local level with supplementation
by the anesthesia provider with analgesics,
sedative-hypnotics, or amnestics
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Injected along a major nerve tract
Nerve Plexus Block or Field Block
Bier Block
Spinal
Epidural
Caudal Block
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Anesthetic injected into major nerve plexus
or the base of a structure
Result is anesthesia of tissue innervated by
that plexus
Used in dental and extremities
Examples: axillary, wrist, ankle, cervical
plexus (CAE)
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Anesthetic injected to an extremity into a vein
below the level of a tourniquet
For arm/wrist/hand surgery that will last less than
1 hour
Blood exsanguinated from extremity with an
esmark, tourniquet is inflated, anesthetic given
Tourniquet prevents anesthetic agent from
circulating above it
Tourniquet will be released slowly to allow for
gradual circulation of the agent to prevent
cardiovascular or CNS effects
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Injected into CSF in the subarachnoid space
between L-3 and L-5 vertebrae
For lower body procedures
Onset 3-5 minutes
Duration 1 ½ hours
Tetracaine most common agent used
Lidocaine and Procaine others used
Epinephrine can prolong effect
Never put patient in Trendelenburg position
with spinal anesthesia
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Disadvantages:
Hypotension
Nausea and vomiting
One time dose means cannot adjust
Temporary or permanent paralysis
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Advantages:
Conscious patient
No respiratory irritation
Bowel contraction enhances abdominal
visibility
Muscle relaxant effects allow easy abdominal
wall retraction
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Injected outside of the dura in the epidural
space that contains the fatty tissue
Injected T-4 vertebral area and down
Lower limb & perineal surgeries and
obstetrics
Thoracic surgeries will be placed for postop pain management
Can be single dose or a catheter can be
inserted to allow for redosing
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Type of Epidural being replaced by the
Epidural Block
Only difference is placement in the epidural
space of the sacral canal
Primarily seen with mothers in labor
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Drager and Datex Ohmeda
Purpose
Basic components: breathing circuit,
ventilator, vaporizer, CO2 absorber,
scavenging system
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Malignant hyperthermia
Recall
CNS depression
Long term effects?
Many more
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History
Concepts
Methods
Machine