Changes in blood gas levels after nebuhaler and nebulizer administration of terbutaline in severe chronic airway obstruction.

Abstract

It has been suggested that patients with severe chronic airway obstruction might suffer dangerous hypoxia after administration of a beta-agonist through an air driven nebulizer. Twenty patients with severe chronic airway obstruction (12 male, mean age 71.1 (SEM 1.5) yr) were monitored with a Biox oximeter and Hewlett-Packard capnometer before and after 4 mg terbutaline was delivered through an air driven nebulizer or Nebuhaler. The eight patients with chronic hypoxia (mean PaO2 6.76 kPa, PaCO2 7.47 kPa. FEV1 0.53 l) experienced a 4.7% increase in oxygen saturation (SaO2) and 2.9% fall in transcutaneous carbon dioxide tension (PtcCO2) (p less than 0.05) during all treatments, followed by a return to initial levels. These changes were attributable to increased ventilation whilst breathing through a mouthpiece. A similar trend was seen in the SaO2 of the twelve normoxic patients (mean PaO2 9.32 kPa, PaCO2 5.34 kPa, FEV1 0.8 l), but there was a sustained fall in PtcCO2 of 3.7% (p less than 0.001) after administration of terbutaline. Inhaled terbutaline in the dosage given did not cause hypoxia in patients with severe chronic airflow obstruction, but nebulizer and Nebuhaler use was associated with a rise in SaO2 related to increased ventilation whilst breathing through a mouthpiece.