8.general anesthetics and local anaesthetics
Post on 11-Aug-2015
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General anaesthetics (GAs) are
drugs which produce reversible loss of all sensations and consciousness.
Features of GA are :1.Reversible loss of consciousness2.Reversible loss of sensations3.Analgesia & amnesia4.Muscle relaxation & abolition of
reflexes
Classification
1. Inhalational GA – a) Volatile liquids : Ether Halothane Enflurane Isoflurane Desflurane
b) Gas : Nitrous oxide
2. Parenteral GA – a) Inducing drugs – Thiopentone
sodium Propofol Etomidate
b) Slow-acting drugs – BZDs : Diazepam, lorazepam Ketamine : Dissociative
anesthesia Opioids : Fentanyl, alfentanil
Therapeutic uses :
For operations on head, neck & face For induction and maintenance of anaesthesia – cardiac catheterization, bronchoscopy Short procedures – dressing of burns As an adjuvant to anaesthetics for
effective analgesia Postoperative pain
Complications of GA –
A. During anaesthesia : respiratory depression salivation, respiratory secretions cardiac arrhythmias, asystole fall in BP aspiration of gastric contents laryngospasm & asphyxia delirium, convulsions
B. After anaesthesia : nausea & vomiting persisting sedation pneumonia organ toxicities – liver & kidney damage nerve palsies cognitive defects
Local anaestheticsLocal anaesthetics
LAs are drugs which when applied
topically or injected locally, block
nerve conduction & cause reversible
loss of all sensations in the part
supplied by the nerve.
Cocaine
Lignocaine
Benzocaine
Tetracaine
Procaine
Prilocaine
Bupivacaine
Ropivacaine
Mechanism of action -
Local anaesthetics
Block voltage-gated Na+ channels
No entry of Na+ ions into the cell – no depolarization
No generation of action potential
No generation and conduction of impulse to CNS
Local anaesthesia
Therapeutic uses : Anaesthetize mucous membrane of the eyes, nose, mouth, cornea, urinary & upper respiratory tracts
Abscess drainage
Surgery – lower & upper limbs, lower abdomen,
perineum, caesarean section
Excision of small swellings, suturing of cut wounds, dental procedures
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