It is known in physiology that respiration rate is more or less determined by concentration of CO2 in the blood. Probably doesn't need to be independently tested.

You’d still want to test. And if it was increased, the next thing to test would be whether a 10% increase in baseline respiratory rate was benign. It’s not obvious that it would be, since breath is so tightly regulated.

OP spoke with rather more certainty than warranted.