pulse oximeters and ionisers

Hi

I'm new to forum and am just back from another night in hospital with my 4 yr old who despite needing venotlin/ steroids/hospitalisation every time he gets a cough (this was a mild tickly cough)has not been diagnosed as asthmatic. Most times I self medicate him which works well but occasionally he starts to deteriorate rapidly early evening so I take him in as I know I'm going to have problems with him in the night. It is the same story every time we go - by the time he gets to hospital the cold air has perked him up and the wheezing reduces and they want to send him home until I persist they take his sats because his stomach 'labours'- (which none of them seem to check until I point it out) - they then take his sats - begrudgingly! and realise that they are usually in the mid 80's by this point- which is when they take him up to the ward, start multidosing and send him for yet another chest xray because the minimal wheeze doesnt account for the ox sats.He usually needs 2 close multidoses and steroid before he starts to improve - and then improves rapidly. Does anyone else have a similar story? - I feel, maybe unfairly, that I do the diagnosing and suggest the treatments to the hospital- maybe its just because I know my child better than anyone and that if I was less assertive I could have ended up with serious problems between 2 and 4a.m a few times. I was thinking of buying my own pulse oximeter so I can check his sats myself before going to hospital and also to keep a diary of events- is this a good idea -can anyone recommend an oximeter, I was also thinking of getting an ioniser for his bedroom- again and recommendations would be greatly appreciated.thanks

Cate