general and local anaesthetics

general anaesthesia

Completely knocked out, cannot even breathe

local anaesthesia

no parlysis of resp muscles, elimination of pain in specific tissues

overton meyer theory

• potency varies directly with lipid solubility

• fat soluble drugs are stronger than water soluble

• nerve cell membranes and BBB has high lipid content

general anaesthetics indications

• during surgery

• rapid onset

• used in electroconvulsive therapy for severe depression

Gen an AE

• vary according to dosage and drug used

• primarily affect heart, peripheral circulation, liver, kidneys, resp tract

• myocardial depression is commonly seen

malignant hyperthermia

occurs during or after volatile inhaled gen an or neuromuscular blocking drug (NMBD) succinylcholine

sudden elevation in body temp (>40)

tachypnea, tachycardia, muscle rigidity

life threatening emergency

tx with cardioresp supportivce dantrolene sodium (skeletal muscle relaxant)

Gen an interactions

antihypertensives: increased hypotensive effects

beta blockers: increased myocardial depression

nitrous oxide

laughing gas

only inhaled gas currently used as gen an

weakest of all gen ans

used for dental procedures or adjuct anesthesia

propofol

parenteral

used for induction and maintenance of gen an

sedation for mechanical ventilation in CCU

lower doses: sedative hypnotic for moderate sedation

caution in pts that are hemodynamically unstable

procedural sedation

AKA conscious and moderate sedatin

preserves pts ability to maintain own airway and respond to verbal commands

combo of IV benzodiazepine or propofol and opiate analgesic

anxiety and sensitivity to pain are reduced and pt cannot recall procedure

rapid recovery, safer than gen an

intrathecal local an

spinal canal, or subarachnoid space

local an suffix

-caine

paralysis effect

1. autonomic activity lost

2. pain and other sensory func lost

3. motor activity lost

recovery occurs in reverse order

local an uses

surgical, dental, diagnostic procedures

tx of certain types of persistent plan

spinal anaesthesia

local an give by

infiltration

nerve block

some local an used for infiltration or nerve block are combines with vasoconstrictors to:

• prevent systemic absorption

• confine local an to injected area

• reduce local blood loss

nerve block indications

used in variety of diagnostic procedures: larynoscopy, brpnchoscopy, esophagoscopy

injected directly into or around nerve trunks or ganglia

local an infiltration AE

• “spinal headache”

  • 70% of pt experience inadvertent dural puncture during epidural an or undergo intrathecal an

local infiltration an tx

bed rest. analgesics, caffeine, blood patch

neuromusc blocking

also paralyze breathing muscles

used with anaesthetics during surgery

need superficial mechanical ventilation

• pt may be paralyzed but conscious

depolarizing drugs (neruomusc blocking)

rapid onset, short duration (ex. succinycholine)

nondepolarizing drugs (NMBD)

short acting, intermediate acting, and long acting

NMBD paralysis process

1. muscle weakness

2. total flaccid paralysis: fingers and eyes, then limbs and trunk, then intercostal muscles

3. NMBDs DO NOT CAUSE SEDATION OR PAIN RELIEF

recovery occurs in reverse

NMBD indications

• MAINLY for facilitating controlled ventilation during surgeries

• reduce muscle contraction in area that needs surgery

• diagnostic drugs for myasthenia gravis

NMBD depolarizing drugs

succinylcholine

pancuronium bromide