Anaesthetics Flashcards
Describe the different classifications of anaesthetic. (5)
General (inhalation or intravenous) or local (regional).
Describe the concept of conscious sedation. (4)
Small amounts of anaesthetic or benzodiazepines used to produce a “sleepy” state - maintain verbal contact but feel comfortable. Used frequently in dentistry.
Describe the process of administering anaesthetics in practice. (8)
1 - premedication - hypnotic like benzodiazepine.
2 - induction - usually IV but can be inhalational.
3 - interoperative analgesia - usually an opioid.
4 - muscle paralysis - facilitates intubation / ventilation / stillness.
5 - maintenence - IV pump or inhalational
6 - surgery
7 - reversal of muscle paralysis and post operative analgesia
8 - provision for PONV.
Describe examples of volatile general anaesthetics. (3)
N20 - anaesthetic and analgesic
Xenon - neuroprotective so good in children.
Most contain Cl or F.
Name 4 examples of intravenous anaesthetics. (4)
Propafol
Barbiturates
Etomidate
Ketamine
Describe stage 1 of Guedel’s Signs. (5)
Analgesia - conscious, muscle tone normal, eye movements slight, breaking deep and regular.
Describe stage 2 of Guedel’s Signs. (7)
Excitement - unconsciousness, muscle tone increased, eye movements increased, breathing erratic, delirium occurs.
Caused by the anaesthetic reaching the brain.
Describe stage 3 of Geudel’s signs. (5)
Surgical anaesthesia - muscle tone relaxes, no eye movements, breathing slowing. When the surgery occurs.
Describe stage 4 of Geudel’s signs. (5)
Respiratory paralysis - flaccid, no eye movements, respiratory effort stops, death if not ventilated.
Describe the concept of MAC. (8)
Minimum alveolar concentration.
The [alveolar] at which 50% of patients fail to move to surgical incision when unpremeditated, and on 1atm of drug given inhalationally with O2 and air.
It is a measure of volatile anaesthetic potency.
At equilibrium, [alveolar] = [spinal cord].
Name 7 things that affect MAC and say in which direction they will change it. (14)
Age (higher in infants, lower in the elderly)
Hyperthermia (increased), hypothermia (decreased)
Pregnancy (increased)
Alcoholism (increased)
Central stimulants (increased)
Other anaesthetics or stimulates (decreased)
Opioids (decreased).
Describe the concept of a blood gas partition. (3)
How much the drug likes being in the blood.
Low value means fast induction and recovery because the drug gets quickly to the brain.
Describe the concept of oil gas partition. (3)
How lipid soluable a drug is.
Determines potency and the amount of drug needed eg in fat people.
Less lipid soluable = more potent.
Describe why nitrous oxides is often given with anaesthetics. (2)
It lowers the MAC of other anaesthetics so less of the other drugs needs to be given.
Describe the stepwise pathway of GABA receptor inhibitors. (3)
Anxiolytics > sedation > anaesthetics.
Describe which anaesthetics act on GABA receptors and which act on glutamate receptors. (3)
Xe, N2O and Ketamine act of glutamate.
All others act on GABA.
Describe the four targets in the brain for anaesthetics and Explain why they are targeted. (8)
Reticular formation - to lower consciousness
Hippocampus - memory depression
Brainstem - respiratory and some CVS centres depressed.
Spinal cord - dorsal horn depressed for analgesia.
Describe the common characteristics of local anaesthetics. (4)
Lipid soluable - more = greater potency
pKa relative to time of onset - more alkali (lower pKa) = faster onset
Chemical links - Ester = faster metabolism, aside = slower.
Protein binding - more bound = linger duration.
Describe the procedures commonly done under local anaesthetic. (5)
Dentistry Obstetrics Patient-awake regional surgery Post-op pain management Chronic Pain management.
Give three examples of local anaesthetics. (3)
Lidocaine, procaine, bupivacaine.
Describe the structure of local anaesthetics. (3)
Aromatic ring linked (Ester or amid link) to an amino group.
Describe the effect that adrenaline has on local anaesthetics. (3)
Increases duration of action and decreases spread because it vasoconstricts.
Describe the common side effects of anaesthetics. (5)
PONV CVS - hypotension PODC (delirium and confusion) Chest infection Anaphylaxis
Describe the Mallampati Scoring system. (5)
How much soft palate you can see when trying to intubation. I - complete soft palate visible II - Complete uvula III - only base of uvula IV - no soft palate
Describe the Cormack-Lehane Classification. (7)
How much you can see on direct laryngoscopy following head tilt chin lift, and external laryngeal manipulation. I - full view of cords II - epiglottis only III - top of epiglottis IV - nothing.
