There is a second device "Sonosentry" It is a standalone device and does not require a mobile device.
There is also a third device, wHolter (wheeze holter) this is an overnight recorder designed to detect nocturnal asthma. - Just in case you can't get your local gp to sleep with you.
and would you believe a forth device, the pulmotrack. Designed for hospital use and continuous monitoring.
oh and yes, fda approval for last two