[Which compressor should be used to deliver pentamidine aerosols with the Respirgard II?]

Prophylaxis against pneumonia due to Pneumocystis carinii is most often carried out using pentamidine administered as an aerosol. For reasons both of comfort and cost this technique should be developed at home or at least in an extra-hospital environment. Using the Respirgard II as the nebuliser of reference this requires a compressor. We have assessed four different compressors and compared these to pressurised oxygen used in a hospital environment. During the course of nebulisation with a pentamidine aerosol two physical factors may coincide to limit their efficacy. First the deposition of some of the particles on the walls of the apparatus and secondly the production of a particle size which is incompatible with alveolar deposition. This study showed that according to the source of compressed air: 1) the fraction of the pentamidine solution found in an aerosol at the mouthpiece varies from 29 to 62%; 2) the fraction of the aerosol whose particle size is suitable for alveolar deposition (1 to 3 microns) varies from 35 to 48%. The product of these two fractions enables an assessment of the efficiency of each apparatus: 14 to 24% of the pentamidine solution may be deposited at the alveolar level. In addition to this efficiency the duration of the session (from 25 to 50 minutes) for each machine should be taken into consideration when considering the choice of the compressor to be coupled with the Respirgard II in order to improve the comfort and therefore the compliance to the treatment.