A self-contained, portable H2/CO2 (air) ratio apparatus has an exhaled breath system, an air analyzing chamber, a hydrogen concentration analyzer, a carbon dioxide (air) concentration analyzer, an air outlet, a computational analyzer and a display unit. The display unit can be a part of the self-contained, portable H2/CO2 (air) ratio apparatus, remotely a part of the self-contained, portable H2/CO2 (air) ratio apparatus, or combinations thereof. The apparatus can assist in the diagnosis of a neonatal patient developing necrotizing enterocolitis and/or lactose intolerance.
