What to do for the best
Okay, so let’s look at the decision to give the nebuliser.
We have heard that there is wheeze on one side of the chest, but no other features to suggest bronchospasm (as seen in asthma). Wheeze can occur when any airways are narrowed by swelling (oedema) or secretions (in infection or in some chronic lung disease like that seen in cystic fibrosis). Asthma is associated with poor expiratory flow and severe asthma (of the sort to cause a marked reduction in oxygen saturations) will normally be accompanied by marked recession and prolonged expiration as the child tries to force the air past the obstruction on expiration. You can get silence on just one side of the chest in acute severe asthma if there is a mucous plug blocking air to one lung, but this is an unusual sign.
Marley is grunting and has no prolonged expiration so no real indications to give the nebuliser. You might argue that there is little harm in nebulising at this stage but I would challenge that. Marley is already tachycardic and a salbutamol neb will only push his heart rate up further making it difficult to decide whether further increase is due to the nebuliser of worsening tachycardia indicating sepsis. In addition, repeated salbutamol can be associated with the development of lactic acidosis and an acidotic patient will breathe heavily to try to combat the acidosis. This could further compound the problems of assessment.