Might have to do with artifacts in the waveform r/t pt movement (shaking the transducer cable?) Not sure. Just hazarding a guess.
(Which brings up an old trick: When you are confronted with a patient who has a lot of lines, pick a transducer and shake it. nhe waveform that goes crazy is the line in question. Given how badly the OR can entangle people [disentangled a central line from a foley from a peripheral IV the other day but that's another story entirely

] it actually comes in handy!)