ANESTHESIA PART I

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ANESTHESIA PART I
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Anesthesia

• Types of
• Concepts
• Administration Selection

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Anesthesia

• Definition Lack of Sensation
• Describes a process that is used to alleviate
  pain and suffering during a surgical procedure

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Optimal Anesthesia

• 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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Hypnosis

• 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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Anesthesia

• Lack of sensation
• Allows for pain-free surgery
• Ranges from topical, local, regional and general
  (systemic) agents

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Amnesia

• Lack of recall of surgical events
• Allows for more cooperative relaxed patient

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Muscle Relaxation

• 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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Patient Positioning

• Allows for surgical site exposure/access
• Allows for monitoring of the surgical patient
• Allows/provides physiological homeostasis

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Homeostasis of Vital Functions

• Maintenance of the patients 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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Methods of Administration

• Determining the Right Anesthetic
• Patients 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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American Society of Anesthesiologists (ASA)

• 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

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• Class 2- Mild to moderate disease
• present (controlled HTN, asthma,
  
• controlled diabetes, mildly obese,
• anemic, tobacco use) that does not interfere
  with ADLs
• Age less than 1 year or greater
• than 70 years old

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• 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) that interfere with ADLs

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• Class 4- severe disease (s) present that are
  life-threatening (unstable angina, CHF,
  respiratory disease that is
• debilitating, liver failure, kidney failure,
• myocardial infarction in progress or in
• the last 24 hours)

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• Class 5- Has little chance of survival, but
  is operated on as a last ditch effort or at the
  request of family members

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• Class 6- Is brain dead/life support is
• being provided
• This is an organ harvest or
• procurement

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• (E) Emergency Modifier- an E is added
• to the Class in cases of emergency
• surgery

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Goal of Anesthesia

• Patient safety
• Optimal results

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Anesthetic Agents

• 2 types
• 1. General
• Focus on altering state of
• consciousness, awareness and pain
• perception
• 2. Nerve Conduction Blockade
• Focus on preventing sensory nerve impulse
• transmission

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General Anesthesia

• Combined to deliver Balanced Anesthesia
• Inhalation agents
• Intravenous agents
• Less Common
• Intramuscular agents
• Instillation

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Components of General Anesthesia

• Amnesia
• Analgesia
• Anesthesia
• Muscle Relaxation
• Together provide Balanced Anesthesia

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Stages of General Anesthesia

• I. Amnesia stage is lightest stage that
  begins with administration of agent ends with
  loss of consciousness
• Good stage for MAC
• II. Excitement or Delirium stage from loss of
  consciousness to loss of eyelid reflex and
  regular breathing
• Patient movements are uninhibited
• Might see vomiting, laryngospasm, hypertension,
  tachycardia
• 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
• 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
• Autonomic response is totally blocked to all
  stimuli

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Phases of Anesthesia

1. Preinduction begins with premed administered and
   ends when anesthesia induction begins in OR
2. Induction from consciousness to unconsciousness
3. Maintenance surgery takes place during this
   requires maintenance of physiological function by
   anesthetist
4. Emergence as surgery is completed (start to wake
   up), restoration of gag reflex, extubation
5. 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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Advantages verses Disadvantages
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General Anesthesia

• Inhalation Agents
• Nitrous Oxide (N²O)
• Ethrane (Enflurane)
• Forane (Isoflurane)
• Halothane (Fluothane)
• Sevoflurane (Sevoflurane)
• Suprane (Desflurane)

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General Anesthesia

• Intravenous Agents
• 1. Barbiturates
• Short acting
• Anesthesia
• Not analgesic
• Pentothal (thiopental)
• Brevital (Methohexital)

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General Anesthesia

• Benzodiazepines
• Sedative and amnesiac effects
• Versed (Midazolam)
• Valium (Diazepam)
• Ativan (Lorazepam)

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General Anesthesia

• Individual Agent
• Propofol (Diprivan)
• Sedative/Hypnotic
• Anesthetic
• Amnesiac
• No Analgesia
• No Muscle Relaxation

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General Anesthesia

• Narcotics
• Maintenance of general anesthesia
• Anesthetic
• Sublimaze (Fentanyl)
• Alfenta (Alfentanil)
• Sufenta (Sufentanil)
• Morphine (Morphine Sulfate)

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General Anesthesia

• 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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Nerve Conduction Blockade

• Includes
• Topical anesthesia
• Local anesthesia
• Regional anesthesia
• Spinal (intrathecal) block
• Epidural block
• Caudal block
• Nerve plexus block

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Topical Anesthesia

• 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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Local Anesthetics

• 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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Local Anesthesia with MAC

• 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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Regional Anesthetics

• Injected along a major nerve tract
• Nerve Plexus Block or Field Block
• Bier Block
• Spinal
• Epidural
• Caudal Block

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Nerve Plexus Block

• 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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Bier Block

• 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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Spinal Block

• 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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Spinal Block

• Disadvantages
• Hypotension
• Nausea and vomiting
• One time dose means cannot adjust
• Temporary or permanent paralysis

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Spinal Block

• Advantages
• Conscious patient
• No respiratory irritation
• Bowel contraction enhances abdominal visibility
• Muscle relaxant effects allow easy abdominal wall
  retraction

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Epidural Block

• 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 post-op
  pain management
• Can be single dose or a catheter can be inserted
  to allow for redosing

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Caudal Block

• 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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Summary

• Anesthesia Types
• Anesthesia Administration Selection