My daughter has bronchiolitis and her oxygen saturation today fell to 92. after receiving several meds via nebulizer and her vein. cause?

Bronchiolitis: Bronchiolitis is caused by viruses. The most common virus causing severe disease is the RSV or respiratory syncyitial virus. Sounds like your daughter was admitted to the hospital and being taken care of. One advice: the pulse ox varies all the time and perhaps her reading of 92 was only transient. Please be patient with her recovery as RSV always takes time to run its course in a lot of cases.

Mismatch: between areas in the lungs where the oxygen can get through constricted airways and those parts of the lung tissue where the most of the blood is circulating creates the drop in percentage of oxygenated hemoglobin (saturation). 92% is worrying, but if it does not drop any further, is not life-threatening in a 15 months old, as long as there is prompt access to care and adequate monitoring