Anaes Vivas · Volatile & inhalational agents
Data viva — the agent-analysis trace (inspired and end-tidal agent)
A data viva on the multi-gas agent trace — the inspired versus the end-tidal (alveolar) concentration, the FA/FI ratio as the measure of uptake and equilibration, and what the widening or narrowing gap tells you about depth and emergence.
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Target exams
ANZCAFRCAABAEDAIC
Prompt
A multi-gas analyser trace showing the inspired and end-tidal concentrations of sevoflurane, oxygen, and nitrous oxide during an inhalational induction, with the inspired sevoflurane at 8 per cent and the end-tidal rising towards it.
Stimulus
A multi-gas analyser showing the inspired and end-tidal concentrations of sevoflurane (and oxygen and nitrous oxide). During an inhalational induction the inspired sevoflurane is 8 per cent; the end-tidal trace rises from zero and approaches, but does not immediately reach, the inspired value. The examiner asks you to interpret the gap.
References2ShowHide
- [3]Sonner JM, Antognini JF, Dutton RC, Flood P, et al. Inhaled anesthetics and immobility: mechanisms, mysteries, and minimum alveolar anesthetic concentration. Anesthesia & Analgesia, 2003.PMID 12933393
- [4]Bersten AD, Soni N (eds) Oh's Intensive Care Manual. 8th edition, Elsevier, 2018.