Anaesthetics

Question 1

List some examples of inhalational and IV anaesthetics

Answer 1

Inhalation - N20, Xe

IV - propofol, barbiturates, ketamine

Question 2

Recognise proposed pharmacological MOAs e.g. agents acting at LGICs

Answer 2

Potentiate GABAa and glycine activity - inhibitory transmitter, LGIC (Cl- conductance), hyper polarises, lowers excitability –> depresses CNS activity
Inhibit NMDA and nicotinic ACh receptors - excitatory transmitter (glutamate), inhibit excitation, lowers Ca2+ current e.g. Xe, N20, ketamine

Question 3

Describe the term ‘minimum alveolar concentration’ (MAC) and what it is determined and affected by

Answer 3

MAC = alveolar pressure at 1atm at which 50% of subjects fail to move to surgical stimulus
Determined by - fat solubility
Affected by - age, core temperature, pregnancy, alcoholism, central stimulants, other sedatives, opioids

Question 4

Describe the main stages of anaesthetic depth

Answer 4

Stage 1 - analgesia, unconscious
Stage 2 - unconscious, erratic breathing
Stage 3 - surgical anaesthesia (increasing depth)
Stage 4 - respiratory paralysis, death

Question 5

Describe the main stages of anaesthetic procedure

Answer 5

Pre-medication - hypnotic/anxiolytic e.g. benzodiazepine
Induction - IV/inhalation
Intraoperative analgesia - opioids
Muscle paralysis - intubate/ventilate
Maintenance
Reversal of muscle paralysis
Recovery - post operative analgesia, anti N/V

Question 6

List some common ADRs with anaesthesia

Answer 6

Local - vomiting, hypotension, chest infection, post operative cognitive dysfunction
General - cardiovascular toxicity (Na+ channel blockers)