Lecture 10 - Inhalation and Intravenous Anaesthetics - Part I

Question 1

Timeline of anaesthetics?

Answer 1

beginning of anaesthetic: Pi > PA > Pa > Pbrain; end of anaesthetic vice versa

Question 2

Meyer-Overton hypothesis?

Answer 2

explanation non-specific effect vased on disruption of ion channel function based on lipid solutbility

Question 3

Flaw of Meyer-overton Hypothesis?

Answer 3

not all lipophilic agents produce anaesthesia; likely work through GABA modulation in brain and glycine modulation in spinal cord

Question 4

MAC?

Answer 4

minimal alveolar concentration producing immobility on standard surgical stimulus in 50% of patients - expressed as % of alveolar gas and is inversibly proportional to potency

Question 5

Factors increasing MAC?

Answer 5

youth, hyperthermia, hyperthyroid, upper drugs, heacy alcohol

Question 6

Factors decreasing MAC?

Answer 6

old age, hypothermia, hypothyroid, downer drugs, pregnancy, hypoxia

Question 7

End tidal agent?

Answer 7

fraction of drug that has reached alveolar but does not proceed to the blood

Question 8

CNS Pharmacodynamics of inhaled agents?

Answer 8

hypnosis, immobility, amnesia, dose related increase in CBF and ICP

Question 9

CVS pharmacodynamics of inhaled agents?

Answer 9

peripheral vasodilation leading to lowered BP, unchanged HR, little effect on stroke volume

Question 10

Respiratory pharmacodynamics

Answer 10

respiratory depressant, impair response to hypoxia, impair response to high CO2, bronchodilation

Question 11

Nitrous oxide as an analgesic?

Answer 11

odourless non-flammable gas, low potency, rapid onse, analgesic, many adverse effects

Question 12

Halothane?

Answer 12

sweet and non-pungent, intermediate blood gas solubility, slow onset

Question 13

Isoflurane?

Answer 13

pungent, potent, intermediate solubitilty and onset, CV stability

Question 14

Desflurane?

Answer 14

pungent intermediate potency, rapid onset and offset (ideal for fast wake up), is unique in changing HR and airway irratant