high MPV is normal if you have some bleeding disorder. Once you have rule out any bleeding, high MPV means activated platelets: It can be related to hypoxia or inflammation or diabetes;
Do you have classic inflammatory markers?
If you don't have these markers, if you don't have diabetes, then you have to look for chronic or intermittent hypoxia.
Chronic hypoxia can happen with breathing obstruction for example.
Intermittent hypoxia can happen with bradypnea/hypopnea/apnea.
Do you have high bicarbonates in your blood (I mean bicarbonates close to the upper limit?)