Inhaled Fenoterol-Ipratropium Bromide in Mechanically Ventilated Patients with Chronic Obstructive Pulmonary Disease

In 18 patients with chronic obstructive pulmonary disease intubated and mechanically ventilated, we prospectively randomized 200 μ g fenoterol-80 μ g ipratropium bromide (four puffs) from a metered-dose inhaler (MDI) versus 1.25 mg fenoterol-500 μ g ipratropium bromide in 5 ml saline from a nebulizer (NEB). Respiratory mechanics were assessed before and 30 min after the end of each delivery by the rapid end-inspiratory airway occlusion technique. We did vary on single breaths the inflation flow (V˙) from 0.2 to 1.2 L · s− 1, at constant inflation volume. The total respiratory resistance of the respiratory system (Rrs) was partitioned into airway (Rint,rs) and tissue ( Δ Rrs) resistances. We found that Rrs was equivalently reduced, from 16.49 ± 1.37 to 14.85 ± 1.88 cm H2O · L− 1 · s with MDI (p < 0.05) and from 18.04 ± 1.85 to 15.15 ± 1.33 cm H2O · L− 1 · s with NEB (p < 0.01). Whereas the prevailing effect of MDI was to reduce Rint,rs, that of NEB was to decrease Δ Rrs. In addition, the V˙ resistance of t...