The delivery of bronchodilators with metered-dose inhalers (MDI) in mechanically ventilated patients has received considerable interest in recent years [1][2][3][4][5]. It has been shown that MDI adapted to the inspiratory line of the ventilator using a spacer device are as effective as nebulizers, despite a significantly lower dose of bronchodilator given by the MDI [1][2][3][4][5]. A spacer device is thought to be fundamental in order to demonstrate the efficacy of the bronchodilatory therapy given by MDI [1][2][3][4][5]. Studies that delivered bronchodilators with MDI directly to the endotracheal tube failed to demonstrate any beneficial effect, even after the administration of high doses of bronchodilators [6]. The use of MDI has several advantages over the nebulizer, such as reduced cost, ease of administration, less personnel time, reliability of dosing and a lower risk of contamination [7][8][9][10].The technique of administration of bronchodilators in mechanically ventilated patients using an MDI and a spacer is an important factor that determines the efficacy of this therapy. Proper timing of the drug delivery, adequate tidal volumes, relatively low inspiratory flows and application of end-inspiratory pause (EIP) (breath-hold) are some of the variables that have been suggested to enhance drug delivery to target sites [4,5]. In particular, EIP of 3-5 s duration has been thought to be an important factor in the success of MDI therapy [1,11]. However, although breath-holding is a prerequisite for optimal drug delivery in spontaneously breathing nonintubated patients, the effect of EIP on the efficacy of MDI therapy in mechanically ventilated patients is not known. The purpose of the present study was, therefore, to examine the effect of EIP on the bronchodilation induced by β 2 -agonists administered with an MDI and a spacer, in a homogeneous group of mechanically ventilated patients with chronic obstructive pulmonary disease (COPD).
MethodsTwelve patients (9 males and 3 females) with COPD, requiring mechanical ventilation to manage acute respiratory Twelve patients with COPD, mechanically ventilated on volume-controlled mode, were prospectively randomized to receive six puffs of salbutamol (100 µg·puff -1 ) either with or without EIP of 5 s duration. Salbutamol was administered with an MDI adapted to the inspiratory limb of the ventilator circuit using an aerosol cloudenhancer spacer. After a 6 h wash-out, patients were crossed over to receive salbutamol by the alternative mode of administration. Static and dynamic airway pressures, minimum (Rmin) and maximum (Rmax) airflow resistance, the difference between Rmax and Rmin (∆R), static end-inspiratory respiratory system compliance (Cst,rs) and cardiac frequency (fC) were measured before and at 15, 30 and 60 min after salbutamol administration.Salbutamol caused a significant decrease in dynamic and static airway pressures, Rmin and Rmax. These changes were not influenced by application of EIP and were evident at 15, 30 and 60 min after salbutamol. With and ...