In infants and young children with acute wheezing, clinically significant improvements were observed when albuterol was administered via a valved inhaler (VHC) holding chamber with high in vitro drug delivery versus low in vitro drug delivery. The inhaler catch chambers are not interchangeable for these children. The study showed a difference in efficacy according to in vitro drug delivery. The high delivery resulted in a greater improvement in wheezing symptoms. Low delivery did not produce comparable results. The authors emphasize the need to choose a suitable capture chamber.