Your end-tidal CO2 number might look perfectly fine — and your patient could still be in serious trouble. In this episode, Tracey, Travis, and Maryann go beyond the numbers and break down what your capnograph waveform is actually telling you: what each segment means, what changes signal a problem, and how to respond before things escalate. If you've been glancing at the number and ignoring the wave, this one's for you.
We share real clinical cases — a cat whose bronchial wash suddenly blocked a mainstem bronchus mid-procedure, a Pomeranian with a tumor fragment that migrated into the endotracheal tube during a lobectomy, and a Rottweiler whose neck position created a shark fin during an ophthalmology case — and walk through exactly what the waveform told us and how we acted on it. Plus: a simple bedside manual breath test, why cardiogenic oscillations fool your monitor's respiratory rate counter, and why a sloped inspiratory downstroke mid-dentistry is a warning you should never ignore.
Key Topics Discussed:
Normal Waveform Basics — Travis walks through the "top hat" shape: sharp expiratory upstroke, flat plateau, steep inspiratory downstroke — and why every team member should actively describe the wave, not just note the number.
The Shark Fin — A sloped expiratory upstroke signals impaired exhalation. Culprits include mucus plugs, kinked tubes, challenging patient positioning, PEEP valves, and lower airway disease such as feline asthma.
Lost ET Tube Cuff Seal — A sloped inspiratory downstroke mid-procedure often means the cuff has failed — raising aspiration risk and team inhalant exposure, especially during wet procedures like dentistry.
Rolling Waves Without a Plateau — Travis's simple manual breath test reveals whether a rapid, shallow breather truly needs ventilatory support or is compensating adequately.
Cardiogenic Oscillations — That sawtooth end-plateau pattern is cardiac turbulence, not the patient waking up. Your monitor's automated respiratory rate is unreliable when you're seeing it.
Confirming Tracheal Placement — No capnograph wave after intubation means no CO2 — and in a non-ruminant, that's not a monitor problem. It's a placement problem.
Questions to Think About While You Listen:
When was the last time you actively described your patient's capnograph waveform — not just the number — in the anesthesia record or out loud to a colleague?
If a shark fin appeared mid-procedure while the end-tidal CO2 was still within normal range, what would your immediate next three steps be?
Could you confidently distinguish cardiogenic oscillations from a patient beginning to breathe against a ventilator — and does your team share a common language for that moment?
Team Challenge: Describe the WaveOn your next three cases, describe the capnograph waveform out loud or in the record — even when it looks completely normal. That habit is what lets you catch changes when it counts.
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