Patient history: A 35-year-old woman with persistent severe asthma presented to the ED of a hospital. On a previous admission, she required mechanical ventilation and was transferred to the intensive care unit (ICU) to treat an asthmatic exacerbation. For the past week, she has increased her use of a B2 agonist as rescue medication by 6 to 8 times and has nighttime exacerbations every evening. Physical examination : She is in acute respiratory distress with nasal flaring and a quiet chest with very distant wheezing.
An ABG drawn on 30% oxygen shows a pH of 7.35, PACO2 42 mmHg, PAO2 89 mmHg, and bicarbonate (HC03) of 23 mEq/L. Peak expiratory flow rates are below 40% of the patient's predicted range. Her respiratory rate is 30 breaths/minute, heart rate is 110 beats/minute and regular, and blood pressure is 150/78 mmHg with a pulsus paradoxus of 10 mmHg. What is the next most important…
