Intravenous and Inhalational Anaesthetic Agents
Induction agents, sedatives, volatile agents, uptake, distribution, organ effects, adverse effects and clinical selection.
How to prepare for the current Primary FRCA MCQ
Build mechanisms first, practise calculations with units, connect equipment to failure modes and finish every SBA by choosing the single best answer to the exact lead-in.
Core concepts
Concept 1
Intravenous agents differ in molecular targets, distribution, metabolism, haemodynamic effect and recovery profile.
Exam cue: Link each agent property to induction, maintenance, organ effect or recovery.
Concept 2
For inhalational agents, inspired concentration, ventilation, solubility, cardiac output and circuit delivery shape alveolar and brain partial pressure.
Exam cue: For volatile uptake, reason from partial-pressure gradients rather than dissolved amount alone.
Risk pitfalls and guardrails
Equating low blood–gas solubility with high anaesthetic potency.
Guardrail: Do not choose an option merely because it states a true fact; choose the one that best answers the exact lead-in under the stated conditions.
Predicting an induction dose without considering age, central volume and cardiovascular reserve.
Guardrail: Convert units before substitution and reject an answer whose direction or order of magnitude is implausible.
Memory anchors
What does MAC describe?
A population measure of inhalational anaesthetic potency based on movement response to a standard stimulus.
What favours faster inhalational induction?
A faster rise in alveolar partial pressure, promoted by lower blood–gas solubility and adequate alveolar ventilation.
Why may an IV induction dose need reduction?
Reduced central volume, impaired cardiovascular reserve, advanced age or increased drug sensitivity can magnify effect.
What belongs in an agent comparison?
Mechanism, onset, offset, cardiorespiratory effects, metabolism, adverse effects and clinical context.
Why is emergence not predicted by one half-life?
Redistribution, tissue stores, exposure duration, ventilation and active metabolites can all affect offset.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which intravenous induction agent most commonly causes pain on injection and a fall in arterial pressure from vasodilation?
Which induction agent produces dissociative anaesthesia and usually preserves sympathetic tone?
Answer all questions to submit.
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Move forward only after this module is stable.
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