A capnogram clinicians can actually read
patientmonitorsimulator's capnography waveform keeps the alpha and beta angles that matter at the bedside, instead of a plain triangle that happens to be the right height.
Measured in kPa, the way a Nordic monitor actually reads
EtCO2 shows in kPa rather than mmHg, matching Swedish clinical practice, which the rest of patientmonitorsimulator follows too. Blood pressure on the same screen stays in mmHg, which looks inconsistent at first glance until you remember that's exactly what a real monitor in a Nordic ward shows too.
The two angles that carry the diagnosis
A capnogram has four phases, but it's really two angles that a clinician reads. The alpha angle sits between the rising edge and the plateau: it opens up as airway obstruction worsens, and in a severe bronchospasm it can erase the plateau entirely into what's often called a shark-fin shape. The beta angle sits between the plateau and the downstroke, and it opens with rebreathing. patientmonitorsimulator models both, driven by the rhythm and settings you choose on the controller, not by a fixed shape that only changes height.
A plateau that slopes, on purpose
The plateau itself rises gently across a breath rather than sitting dead flat, because alveoli empty at slightly different rates in a real lung. A perfectly horizontal plateau isn't a cleaner signal, it's a less realistic one.
Rounded corners, for a reason
Building the waveform's transitions as sharp mathematical corners was an early mistake we corrected after a doctor pointed out that no real capnograph produces one. Gas takes time to travel through the sampling line and spreads out on the way, and the sensor itself has a response time. patientmonitorsimulator runs the ideal waveform through a response-time filter that rounds each transition by an amount proportional to how sharp it is, which is exactly what preserves the alpha and beta angles instead of flattening them the way a generic smoothing pass would.
Apnea reads as no reading, not zero
In any cardiac-arrest rhythm the trace goes completely flat at zero: a capnograph measures real exhaled gas, so there's nothing left to add texture to. The number itself shows as "no reading" rather than 0, because end-tidal specifically means the value at the end of an exhaled breath, and an apneic patient has none.
Locked in phase with the breath, always
One breathing engine drives both this waveform and the respiration trace, so the two can never show a patient inhaling on one screen and exhaling on the other.