Improvement of nebulised antibiotic delivery in cystic fibrosis.
AIM
To investigate deposition patterns and to assess the delivery rate of two nebuliser systems in children with cystic fibrosis (CF).


METHODS
Thirty three children with CF on regular treatment with nebulised antibiotics had radioisotope scans performed using technetium-99m labelled aerosol antibiotic generated by a Ventstream nebuliser (median mass diameter (MMD), 3.3 microm; delivery rate, 0. 075 ml/min) under conditions similar to their routine home practice. The inhomogeneity of the images was scored on a 1-10 rating scale (a low score indicating even distribution of the antibiotic), and stomach deposition was measured as a percentage of overall deposition. Twenty patients had a repeat scan using an Optimist nebuliser (MMD, 1.8 microm; delivery rate, 0.02 ml/min).


RESULTS
The mean inhomogeneity scores were 5.4 in the Ventstream group and 3. 5 in the Optimist group. Mean stomach deposition was 17.3% in the 33 patients using the Ventstream nebuliser. There was an inverse relation between height and stomach deposition (r = 0.69). In the 20 patients who had both nebulisers, the mean percentages of stomach deposition for the Ventstream and Optimist nebulisers were 11.8% and 1.6%, respectively. The Ventstream nebuliser delivered antibiotic at an average 2.8 times faster rate than the Optimist nebuliser.


IMPLICATIONS
A smaller particle size results in a more homogenous distribution of the antibiotic in the lungs with decreased stomach deposition. This should not be seen as a recommendation to use the Optimist nebuliser because more antibiotic was delivered to most parts of the lung with the Ventstream because of its increased delivery rate.