Anesthesia
In the “old days” the following were used for
anesthesia.
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Alcohol
Drugs
Ice for numbing
Blow to the head
Strangulation
Anesthesia
Now, anesthesia is designed to focus on
specific systems, such as
• Nervous system
• Skeletal system
• Respiratory system
• GI system
• Endocrine system
• Hepatic system
• Cardiovascular system
Anesthesia
Goals of Balanced Anesthesia
– Amnesia (Loss of memory)
– Adequate Muscle Relaxation
– Adequate Ventilation
– Pain Control
Types of Anesthesia
• Preansthetics agents
• General (inhaled: desflurane,
halothane, isoflurane, Nitrous oxide,
sevoflurane, enflurane; IV:
barbiturate, benzodiazepines,
ketamine, opoids, propofol,
etomidate)
• Local ( Bupivacaine, Lidocaine,
Procaine, Tetracaine)
General Anesthesia
Preanesthetic Medications (antiemetics,
muscle relaxants, Anticholinergics,
antihistamines, Benzodazepines, Opioids)
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Control sedation
Reduce postoperative pain
Provide amnesia
Decrease anxiety
Discussion
What are some of the indicators used
to access general anesthesia?
Answer: Blood pressure,
hypervolemia, oxygen level,
pulse, respiratory rate, tissue
perfusion, urinary output
General Anesthesia
Malignant Hyperthermia
– Side effect of anesthesia
• Fever of 110°F or more
• Life threatening
– Treatment: dantrolene (Dantrium)
Drug List
Inhalant Anesthetics
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desflurane (Suprane)
enflurane (Ethrane)
halothane
isoflurane (Forane)
nitrous oxide
Inhalant Anesthesia Side Effects
• Causes reduction in blood pressure
• May cause nausea and vomiting
nitrous oxide
• Causes analgesia only; no amnesia or
relaxation
• May be given alone or may be given
with more powerful anesthetics to
hasten the uptake of the other agent (s)
• Commonly used for dental procedures
• Rapidly eliminated
desflurane (Suprane)
• Has rapid onset and recovery
• Often used in ambulatory surgery
Intravenous General Anesthesia
• Often dispensed by IV drip
• Very lipid soluble
Drug List
Injectable Anesthetics
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etomidate (Amidate)
fentanyl (Duragesic, Sublimaze)
fentanyl-droperidol
ketamine (Ketalar)
morphine
propofol (Diprivan)
sufentanil (Sufenta)
Drug List
Injectable Anesthetics
Barbituates
– methohexital (Brevital)
– thiopental (Pentothal)
Benzodiazepines
– diazepam (Valium)
– lorazepam (Ativan)
– midazolam (Versed)
propofol (Diprivan)
• Used for maintenance of anesthesia,
sedation, or treatment of agitation
• Has antiemetic properties
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Drowsiness
Respiratory depression
Motor restlessness
Increased blood pressure
fentanyl
• Dosage Forms
– IV
– patch
– lozenge for children
• Used extensively for open-heart
surgery due to lack of cardiac
depression
Benzodiazepines
• Used for induction, short procedures, and
dental procedures
• Useful in controlling and preventing
seizures induced by local anesthetics
• midozolam (Versed)
– fastest onset of action
– greatest potency
– most rapid elimination
Antagonist Agents
Antagonist agents reverse
benzodiazepine and narcotic
overdose.
Drug List
Antagonist Agents
• flumazenil (Romazicon)
• nalmefene (Revex)
• naloxone (Narcan)
Neuromuscular Blocking Agents
• Causes immediate skeletal muscle
relaxation.
– Short Duration
– Intermediate Duration
– Extended Duration
• Used to facilitate endotracheal intubation.
– Allows for easier insertion of endotracheal
tube.
– Keeps airway open.
Drug List
Neuromuscular Blocking
Agents
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atracurium (Tracrium)
cisatracurium (Nimbex)
mivacurium (Mivacron)
pancuronium
rocuronium (Zemuron)
succinylcholine (Quelicin)
vecuronium (Norcuron)
succinylcholine (Quelicin)
• Often called “sux.”
• Only depolarizing agent. All others work as
competitive antagonists to ACh receptors.
• Persistent depolarization at motor endplate.
• Causes sustained, brief period of flaccid
skeletal muscle paralysis.
Reversal of Neuromuscular Blocking
Agents
• Increases the action of acetylcholine by
inhibiting acetylcholinesterase
• Used for reversal of nonpolarizing agents
Drug List
Anticholinesterase Agents
• edrophonium (Enlon)
• neostigmine (Prostigmin)
• pyridostigmine (Mestinon)
Local Anesthesia
Relieves pain without altering
alertness or mental function.
Local Anesthesia
Variety of Dosage Forms
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Topical
Superficial injection (infiltration)
Nerve block
IV
Spinal
Under what conditions would a local
anesthetic be used over a general
anesthetic?
Answer: It is chosen when a
well-defined area of the body is
targeted.
Discussion
Local anesthetics are classified by
their chemistry into two classes.
Ester
Amides
Local Anesthesia
Esters
– Short acting
– Metabolized in the plasma and tissue fluids
– Excreted in urine
Local Anesthesia
Amides
– Longer acting
– Metabolized by liver enzymes
– Excreted in urine
Drug List
Local Anesthesia
Esters
• benzocaine (Americaine)
• chloroprocaine (Nesacaine)
• dyclonine (Cēpacol Maximum Strength)
• procaine (Novocain)
• tetracaine (Cēpacol Viractin, Pontocaine)
Drug List
Local Anesthesia
Amides
• bupivacaine (Marcaine)
• levobupivacaine (Chirocaine)
• lidocaine (L-M-X, Solarcaine, Xylocaine)
• lidocaine-epinephrine (Xylocaine w/ Epinephrine)
• lidocaine-prilocaine (EMLA)
• mepivacaine (Carbocaine)
What functions are lost with local
anesthetics?
Answer
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Pain perception
Temperature
Touch sensation
Skeletal muscle tone