general and local anaesthetic agents
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General and Local
Anaesthetics
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Agents that depress the central nervoussystem (CNS)
Depression of consciousness
Loss of responsiveness to sensory stimulation(including pain)
Muscle relaxation
Anesthesia: the state of depressed CNSactivity
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A state of depressed CNS activity
Two types
General anesthesia Local anesthesia
Balanced anaesthesia
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Agents that induce a state in which theCNS is altered to produce varying degreesof:
Pain relief
Depression of consciousness
Skeletal muscle relaxation
Reflex reduction
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Inhaled anesthetics:
Volatile liquids or gases that are vaporized inoxygen and inhaled.
Injectable anesthetics:
Administered intravenously.
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Inhaled gas: Nitrous oxide (laughing gas)
Inhaled volatile liquids: enflurane
halothane
isoflurane
methoxyflurane sevoflurane
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Used:
To induce or maintain general anesthesia
To induce amnesia
As an adjunct to inhalation-type anesthetics
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etomidate
ketamine
methohexital*
propofol* thiamylal
thiopental
* May also be used as adjunctive agents at lower dosages
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Sedative-hypnotics
Barbiturates (secobarbital, thiopental)
Benzodiazepines (diazepam, midazolam)
Opioids (narcotics)
morphine, fentanyl, sufentanil
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Neuromuscular blocking agents (NMBAs):
Depolarizing agents (succinylcholine)
Nondepolarizing agents (pancuronium, d-Tubocurarine, vecuronium)
Anticholinergics:
atropine, glycopyrrolate, scopolamine
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Varies according to agent.
Overall effect:
Orderly and systematic reduction of sensoryand motor CNS functions.
Progressive depression of cerebral and spinalcord functions.
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General anesthetics used during surgicalprocedures to produce:
Unconsciousness
Skeletal muscular relaxation
Visceral smooth muscle relaxation
Rapid onset, quickly metabolized.
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Vary according to dosage and agent used.
Sites primarily affected:
Heart, peripheral circulation, liver, kidneys,respiratory tract.
Myocardial depression is commonly seen.
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Malignant hyperthermia:
Occurs during or after general anesthesia
Sudden elevation in body temperature (>104F)
Life-threatening emergency
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Also called regional anesthetics.
Used to render a specific portion of the
body insensitive to pain.
Interfere with nerve impulse transmissionto specific areas of the body.
Do not cause loss of consciousness.
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Topical:
Applied directly to skin or mucousmembranes.
Creams, solutions, ointments, gels,ophthalmic drops, lozenges, suppositories.
Parenteral:
Injected into the CNS by various spinalinjection techniques.
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Epidural
Infiltration
Nerve block Spinal
Topical
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lidocaine \lignocaine
mepivacaine
procaine tetracaine
bupivacaine
ropivacaine
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First, autonomic activity is lost.
Then pain and other sensory functions arelost.
Motor activity is the last to be lost.
As local agents wear off, they do so in
reverse order (motor, sensory, thenautonomic activity are restored).
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Local anesthetics are used for:
Surgical, dental, and diagnostic procedures
Treatment of certain types of pain
Infiltration anesthesia.
Nerve block anesthesia.
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Infiltration anesthesia:
Minor surgical and dental procedures.
Injection of the anesthetic solution
intradermally, subcutaneously, orsubmucosally across the path of nervessupplying the target area.
May be given in a circular pattern around theoperative area.
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Nerve block anesthesia:
Used for surgical, dental, and diagnosticprocedures.
Also used for therapeutic management ofpain.
The anesthetic agent is injected directly into
or around the nerve trunks or nerve gangliathat supply the area to be numbed.
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Usually limited.
Adverse effects result if:
Inadvertent intravascular injection occurs.
Excessive dose or rate of injection is given.
Slow metabolic breakdown.
Injection into a highly vascular tissue.
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Also known as NMBAs.
Prevent nerve transmission in certainmuscles, resulting in paralysis of themuscle.
Used with anesthetics during surgery.
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When used during surgery, artificialmechanical ventilation is required.
These drugs paralyze respiratory and skeletal
muscles
Patient cannot breathe on his/her own
Do not cause sedation or relief of pain
Patient may be paralyzed yet conscious
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Depolarizing agents
Nondepolarizing agents
Short acting
Intermediate acting
Long acting
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succinylcholine is the only one
Works similarly to neurotransmitteracetylcholine (ACh), causing
depolarization Metabolism is slower than ACh, so as long
as succinylcholine is present,
repolarization cannot occur Result: flaccid muscle paralysis
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Short acting mivacurium
Intermediate acting
atracurium rocuronium
Long acting
pancuronium d-Tubocurarine
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Prevent ACh from acting at theneuromuscular junctions
Nerve cell membrane is not depolarized,muscle fibers are not stimulated
Skeletal muscle contraction does notoccur
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First sensation felt is weakness.
Followed by total flaccid paralysis.
Small, rapidly moving muscles are affected first
(fingers, eyes), then limbs, neck, trunk Finally, intercostal muscles and the diaphragm
are affected, resulting in cessation ofrespirations.
Recovery of muscles usually occurs in reverseorder.
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Main use: maintaining controlledventilation during surgical procedures.
Endotracheal intubation (short acting).
To reduce muscle contraction in an areathat needs surgery.
Diagnostic agents for myasthenia gravis.
Other uses.
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Few when used appropriately.
May cause: Hypotension (blockade of autonomic ganglia)
Tachycardia (blockade of muscarinicreceptors)
Hypotension (release of histamine)
Effects vary according to site.
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Overdose causes prolonged paralysisrequiring prolonged mechanicalventilation.
Cardiovascular collapse may occur.
Several conditions may increase thesensitivity of a patient to NMBAs.
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Combination of an IV benzodiazepine andan opiate analgesic used.
Anxiety and sensitivity to pain are
reduced, and patient cannot recall theprocedure.
Preserves the patients ability to maintain
own airway and to respond to verbalcommands.
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Used for diagnostic procedures and minorsurgical procedures that do not requiredeep anesthesia.
Topical anesthetic may be applied also.
Rapid recovery time and greater safetyprofile than general anesthesia.
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Always assess past history of surgeriesand response to anesthesia.
Assess past history, allergies,medications.
Assess use of alcohol, illicit drugs, opioids.
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Assessment is vital during pre-, intra-, andpostoperative phases
Vital signs
Baseline labwork, ECG
Pulse oximeter (PO2)
ABCs (airway, breathing, circulation)
Monitor all body systems
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Nursing considerations during theperioperative phase include the:
Preoperative phase
Intraoperative phase
Postoperative phase
Each phase has its own complex and very
specific nursing actions
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Close and frequent observation of thepatient and all body systems.
During a procedure, monitor vital signs,ABCs.
Watch for sudden elevations in bodytemperature, which may indicate
malignant hyperthermia.
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During recovery, monitor forcardiovascular depression, respiratorydepression, and complications of
anesthesia.
Implement safety measures duringrecovery, especially if motor/sensory loss
occurs due to local anesthesia.
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Reorient patient to his/her surroundings.
Provide preoperative teaching about thesurgical procedure and anesthesia.
Teach the patient about postoperativeturning, coughing, deep breathing.
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If an NMBA is to be used for a procedurewhen the patient is to be awake, teach thepatient that he/she may be paralyzed but
still able to hear and feel.