Guidelines for the management of asthma: a summary. British Thoracic Society and others.

Acute severe asthma in adults Recognition and assessment in hospital Features of acute severe asthma * Can't complete sentences in one breath * Respirations 225 breaths/min * Pulse 11O beats/min * Peak expiratory flow (PEF) s 50% of predicted * or best Life threatening features * PEF <33% of predicted or best * Silent chest, cyanosis, or feeble respiratory effort * Bradycardia or hypotension * Exhaustion, confusion, or coma If a patient has any of these features, then measure arterial blood gases.Markers of a very severe, life threatening attack: * Normal (5-6 kPa, 36-45 mm Hg) or high Faco2 * Severe hypoxia: Pao2 <8 kPa (60 mm Hg) irrespective of treatment with oxygen * A low pH (or high H+) No other investigations are needed for immediate management.