Any life-threatening episode of asthma requires early pre-hospital specialized medical management by emergency medical crews. Gravity depends on both clinical criteria and a peak expiratory flow rate (PEFR) more than 30% below either the level predicted by the reference graph or the patient's reference value. Initial treatment combines continuous nebulizations containing a beta2-agonist and ipratropium bromide, with oxygen administration and intravenous corticosteroid bolus. Recommended as second-line treatment in the absence of adequate response are: intravenous magnesium sulphate and continuous-perfusion beta2-agonists (electric syringe), or, in the case of shock, epinephrine. If mechanical ventilation is required, its settings should aim for low tidal volumes, low frequency, and increased expiratory time.