Lecture 5 - Anaesthetics Flashcards
Define anaesthesia
Lack of feeling, perception and sensation
What the non drug methods of anaesthesia?
Cold
concussion
carotid compression
nerve compression
hypnosis
blood letting
What are the drug methods of anaesthesia?
Canabis
alcohol
cocaine
opium
hyoscine (Mandrake)
What are the methods of administration of anaesthesia?
Inhalation
IV
Intradermal
Explain the stages of anaesthesia
Stage 1 - Analgesia
Stage 2 - Excitement
Stage 3 - Anaesthesia
Stage 4 - Medullary paralysis
Describe stage 1 of anaesthesia
conscious, drowsy
can still produce tears
Describe stage 2 of anaesthesia
Loss of consciousness but delirium
irregular cardio-respiration, apnoea, spasticity, gagging
progressively lose more reflexes
Describe stage 3 of anaesthesia
Regular respiration, loss of reflex and muscle tone
used for painful situations
Describe stage 4 of anaesthesia
Depression of cardio-respiration and death
Name some common inhalation anaesthetics
Desflurane
Halothane
Isoflurane
Enflurane
Sevoflurane
Nitrous oxide
Name some common IV anaesthetics
Propofol
Fospropofol
Barbiturates
Benzodiazepines
Opioids
Ketaine
Etomidate
Name the mechanisms of action of anaesthetics
Affect different types of ion channels
Enhance activity of inhibitory ion channels
Reduce neuronal excitability through effects on K+ channels
Block excitatory ligand-gated ion channels
Name the common local anaesthetics
Topical
infiltration
nerve block
spinal
epidural
- DO NOT LOSE CONSCIOUSNESS
Name the common topical anaesthetics
Benzocaine
Lidocaine
Applied directly to the skin or mucous membrane
Commonly given to numb area before an injection
Used to relieve pain or prevent pain from minor burns, irritation, itching
Name the common infiltration anaesthetics
Procaine, chloroprocaine, lidocaine, bupivacaine
Produce loss of sensation restricted to a located area in the Boyd
Injected directly into the area of terminal nerve endings
Used for minor surgical and dental procedures
Define nerve block and give examples of anaesthesia
Lidocaine, prilocaine, bupivacaine
Injection of local anaesthetic to numb the nerves supplying a particular part of the body such as the hand, arm or leg
Define spinal anaesthetics
Single injection with a thin needle that puts the local anaesthetic close to the nerves
Used to numb the lower part of the body
Rapid onset only lasts a few hours
Lidocaine, tetracainene, and bupivacaine
Define epidural
Injection into the space outside the sac
fine plastic tube threaded through a needle and the tube is left in the epidural space
slow onset, long duration of action
Lidocaine, bupivacaine, articaine
What are the side effects of a epidural?
Heart rhythm problems or seizures, hepatoma in the epidural space, headache
What are the side effects of spinal anaesthesia?
Low BP, headache and back pain
Describe the MOA of local anaesthetics
1) Block the voltage gated Na+ channels
2) no entry of Na+ ions into the cell
3) no depolarisation
4) no generation of action potential
5) no generation and conduction of impulse to CNS
Give examples of approaches in surgical anaesthesia
Pre-op (sedation, anxiolysis, amnesia)
- midazolam and other benzodiazepines
Rapid unconsciousness
- i.v. of rapid short acting agent e.g. thiopental
Maintain unconsciousness
- inhalation agents e.g. nitrous oxide, halothane
Supplement analgesia
- i.v. agents e.g. fentanyl
Paralysis
neuromuscular block e.g. suxamethonium
