Anaes Vivas · Measurement & monitoring physics
Data viva — the capnogram waveform
A Primary data viva — infrared measurement of exhaled CO2 with numeric and waveform display; flat oesophageal trace; relentlessly rising EtCO2 in malignant hyperthermia; EtCO2 10 mmHg or less after 20 minutes of CPR predicts death.
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Target exams
ANZCAFRCAABAEDAIC
Prompt
Three capnogram strips are shown: (1) a flat trace at zero over several breaths during attempted intubation; (2) a relentlessly rising end-tidal CO2 unresponsive to increased ventilation; (3) a low end-tidal value during cardiac arrest. Interpret each trace and state the physical principle behind the monitor.
Stimulus
Three capnogram strips are shown: (1) a flat trace at zero over several breaths during attempted intubation; (2) a relentlessly rising end-tidal CO2 unresponsive to increased ventilation; (3) a low end-tidal value during cardiac arrest. Interpret each trace and state the physical principle behind the monitor.[2]
References6ShowHide
- [1]Jaffe MB Infrared measurement of carbon dioxide in the human breath: "breathe-through" devices from Tyndall to the present day. Anesth Analg, 2008.PMID 18713902
- [2]Long B, Koyfman A, et al. Capnography in the Emergency Department: A Review of Uses, Waveforms, and Limitations. J Emerg Med, 2017.PMID 28993038
- [3]Groeneveld NTA, et al. Recognition of esophageal intubation in Dutch prehospital emergency medical services using capnography analysis: a retrospective cohort study. Resuscitation, 2026.PMID 41548748
- [4]Singh A, Kataria S, John G, et al. Diastolic blood pressure and end-tidal carbon dioxide during adult ICU cardiopulmonary resuscitation: association with return of spontaneous circulation. Resuscitation, 2026.PMID 42331277
- [5]Levine RL, Wayne MA, et al. End-tidal carbon dioxide and outcome of out-of-hospital cardiac arrest. N Engl J Med, 1997.PMID 9233867
- [6]Ali SZ, Taguchi A, et al. Malignant hyperthermia. Best Pract Res Clin Anaesthesiol, 2003.PMID 14661655