Generally support - I like the change in formatting. My only query (and this is with the original question) - 3 hrs of continuous nebs is a little bit of a high threshold for ICU. A lot of people will be dead by then!
Example symptoms warranting ICU per Tintinalli Emergency Medicine Manual pp 462-463 are PEFR <25%, and for severe exacerbation unresponsive to intitial treatment, FEEV1/PEFR <40%, PCO2 ≥ 42mm Hg, or severe symptoms/drowsy/confused.