EFFECT OF THEOPHYLLINE ON MUCOCILIARY TRA NSPORT IN VENTILATED INTENSIVE-CARE PATIENTS

Mucociliary clearance represents an important protective mechanism of the upper and lower respiratory tracts whereby inhaled particles and m icro-organisms are removed from the tracheobronchial system. In inbuba ted intensive care unit (ICU) patients, impaired ciliary function and mucus transport are associated with pulmonary complications [9]. Some authors have shown that theophylline increases mucus transport in heal thy subjects and patients with chronic bronchitis [8, 16, 31, 36]. How ever, other investigators have found unconvincing or conflicting resul ts [4, 20, 25]. Therefore, we studied the influence of theophylline on bronchial mucus transport velocity (BTV) in ventilated ICU patients. Methods. The study was approved by the ethics committee of our hospita l. In a placebo-controlled double-blind study, the effect of therapeut ic serum concentrations (10-20 mug/ml) of theophylline on BTV in venti lated patients in a surgical ICU was investigated. Group 1 (n = 10) se rved as controls and received placebo. The patients of group 2 (n = 10 ) were given intravenous infusions of 5 mg/kg body weight theophylline over 20 min, followed by 1 mg/kg per hour. Before administration of t heophylline and 1 h after starting the infusion BTV, serum theophyllin e concentrations, and arterial blood gases were measured. Heart rate a nd blood pressure were registered every 5 min. In an additional study, the effect of theophylline on BTV at subtherapeutic serum concentrati ons (5 mug/ml) was investigated. BTV was measured with a small volume (0.05-0.08 ml) of albumin microspheres labeled with technetium-99m, wh ich was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope. The movement of the microspheres towards th e trachea was visualised and recorded using a scintillation camera [10 ]. Results. The theophylline treatment induced a significant improveme nt in BTV from 3.8 to 7.6 mm/min in the left main bronchus and from 0. 5 to 5.4 mm/min in the right, while placebo was inactive. The increase in BTV, however, was associated with an increase in heart rate; in 3 patients the theophylline infusion had to be stopped because of severe tachycardia. Blood gases and blood pressures did not change. Theophyl line at subtherapeutic concentrations had no effect on either BTV or h eart rate. Conclusions. Theophylline at therapeutic concentrations imp roves bronchial mucus transport in intubated ICU patients. The increas e in BTV may be associated with severe tachycardia, and therefore rout ine application cannot be recommended.