My son is 4 and weighs 34lbs he has an upper n lower respiratory infection he also has asthma oxygen level is 91 is that normal?

SeekEvaluationToday!: The oxygen saturation of 91% is lower than we like to see generally speaking. Given his history of asthma in addition to his current respiratory infection he really needs to be evaluated either in the pediatrician's office today (or the ED if unable to get appointment). It may be that you just need to increase the frequency of his asthma meds, but only after a thorough evaluation.

More information pls: Your son's asthma is not under good control and his asthma plan, pulmonary function testing, and possibly imaging studies will provide more information. He should avoid smoke. I would advise discussing the aerochamber with a mask, with your physician. If there is inflammation in the lung, a steroid preparation can be used .He should be screened for CF, reflux and other causes or triggers.

See doc ASAP: His asthma is out of control ,need to rush him to doctor or nearest ER. Oxygen level is unacceptably low for asthma.