[Effects of ipratropium bromide as a nebulized solution on respiratory function in mechanically ventilated patients]

Ipratropium bromide is an atropine-like bronchodilator with a mechanism of action via the anticholinergic pathway, and which may decrease cyclic guanosine monophosphate. Twenty ventilated patients (14-85 years old) with acute airflow obstruction and wheezing or coughing participated in a double-blind trial of nebulized bronchodilator treatment. Maintenance theophylline with or without a steroid preparation was continued and comparison was made between ipratropium bromide and a placebo. The study was randomized and conducted on two separate days commencing at the same time each morning. It was found that both the inspiratory resistance and the respiratory symptom scores decreased after ipratropium inhalation. The arterial O2 and CO2 tension did not change. Cardiovascular side effects appeared to be minimal. Since lung compliance was not affected by aerosol administration of ipratropium, it is possible that this drug acts only on the large airways. No significant alteration in the mean airway pressure was observed. We conclude that ventilated patients with bronchospasms can benefit from nebulized ipratropium alone. Their responses, assessed in terms of inspiratory resistance and symptom relief, may be explained by the bronchodilatation and better airflow resulting from the inhaled ipratropium.