Presence of pulsus paradoxus, PCO2, sternocleidomastoid retraction, and flow rates have been used at the bedside to assess the severity of acute asthma. In our study of 49 adult patients, pulse rate, respiratory rate and pulsus paradoxus were shown to be significantly higher in patients assuming the upright position on admission to the emergency center; arterial pH, PO2, and peak expiratory flow rate were significantly lower in the upright patients. All upright patients had sternocleidomastoid retraction. Peak expiratory flow rate was 73.3 +/- 5 liters per minute in diaphoretic patients, 134 +/- 21 liters per minute in non-diaphoretic, upright patients, and 225 +/- 7.5 liters per minute in recumbent patients (p less than 0.02). No recumbent patient had a peak expiratory flow rate of less than 150 liters per minute or a PCO2 of greater than 44 mm Hg. The index of Fischl, signifying a need for admission to the hospital if greater than 4, was 4 or higher in 70 percent of upright patients and in 88 percent of diaphoretic patients. Only 7 percent of recumbent patients had Fischi indexes of greater than 4.