Bronchodilators in Patients with Chronic Obstructive Pulmonary Disease on Mechanical Ventilation: Utilization of Metered-dose Inhalers

Abstract

Bronchodilators are used widely in the acute exacerbations of chronic obstructive pulmonary disease (COPD), although their effectiveness is not clearly established. We used three bronchodilators in 20 patients with COPD who were being mechanically ventilated. Two of the bronchodilators, ipratropium bromide and salbutamol, were administered from metered-dose inhalers (MDI) through an adapter to the endotracheal tube, and the third, aminophylline, was administered in the form of intravenous infusion. Before administering each drug, peak airway pressure, end-inspiratory pressure, resistive pressure, and auto positive end-expiratory pressure (auto-PEEP) were measured, and inspiratory resistance (Rins) and compliance were calculated. Heart rate (HR) and blood pressure were also recorded, and arterial pH and blood gas determinations were made. These measurements were repeated 60 min after the administration of aminophylline, 15 and 60 min after administering salbutamol, and 30 and 60 min after administering ipratropium bromide. With these three drugs, airway pressures were reduced, as well as auto-PEEP and Rins, with respect to basal values (p less than 0.05). The changes in compliance were only significant with salbutamol (p less than 0.05). HR was only significantly modified with aminophylline (p less than 0.05). No blood gas change was observed with any of the three drugs. It can be concluded that: (1) the three drugs used in this study were equally effective in producing significant bronchodilation in patients on mechanical ventilation for severe acute exacerbation of COPD; (2) the administration of bronchodilators by MDI in intubated patients through a special adapter was as effective as the intravenous administration of aminophylline.

Bronchodilator delivery with metered-dose inhalers in mechanically-ventilated patients

“…A decrease in values of Rrs,max and Rrs,min occurs following bronchodilator administration in mechanicallyventilated patients [11,12,39,41,50].…”

“…Few investigators have examined the efficacy of bronchodilators in mechanically-ventilated patients [8,11,12,15,[38][39][40][41][42][43][44]. Early studies showed promising results following bronchodilator administration by a MDI [42][43][44], and yet the data were ignored for several years.…”

“…Therefore, a decrease in expiratory resistance should be accompanied by a decrease in PEEPi. However, a decrease in PEEPi has not been uniformly demonstrated after bronchodilator administration in mechanically-ventilated patients, probably because other factors, such as minute volume and expiratory time, influence the level of PEEPi [11,12,39,50]. In addition, LEATHERMAN et al [59] suggested that measurement of PEEPi by airway occlusion may underestimate the degree of dynamic hyperinflation.…”

“…The potential for atrial and ventricular arrhythmias must be borne in mind when high doses of beta-agonists are given in critically ill patients [60,61]. Although most studies have reported no adverse effects following administration of albuterol with a MDI to mechanically-ventilated patients [8,10,11,[38][39][40][41], we observed a dose-dependent increase in heart rate, becoming significant after administration of a cumulative dose of 28 puffs [12]. CFCs, used as propellants in a MDI, have a short half-life (<40 s) in blood after administration of a MDI to healthy volunteers.…”

Inhalation Therapy in Patients Receiving Mechanical Ventilation: An Update

“…The goals of bronchodilator therapy are to reverse bronchoconstriction, decrease the work of breathing, and/or relieve dyspnea. Administration of either aerosolized b-adrenergic (26,29,(74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84)(85)(86)(87)(88)(89)(90)(91)(92)(93) or anticholinergic drugs (77,79,83,86) produces significant bronchodilator responses in ventilated patients. The combination of fenoterol and ipratropium bromide was found more effective than ipratropium alone in ventilated patients with COPD.…”