S Soommee tteecchhnniiccaall ffaaccttoorrss iinnfflluueenncciinngg tthhee iinndduuccttiioonn o off s sppuuttuumm ffoorr c ceellll a annaallyyssiiss

Some technical factors influencing the induction of sputum for cell analysis. T.A. Popov, M.M.M. Pizzichini, E. Pizzichini, R. Kolendowicz, Z. Punthakee, J. Dolovich, F.E. Hargreave. ERS Journals Ltd 1995. ABSTRACT: Inhalation of hypertonic saline aerosol is a relatively noninvasive method to obtain sputum for examination of inflammatory processes in the airways. We investigated some technical factors which might influence the success of induc- tion and sputum cell counts. In total, twenty six asthmatic and 13 healthy subjects, unable to raise sputum spon- taneously, inhaled nebulized saline for three 7 min intervals. In three randomized, cross-over studies we repeated sputum induction on separate days with two ultra- sonic nebulizers (De Vilbiss Ultraneb 99 and Fisoneb) and one jet nebulizer (Pari LL with Master Compressor) (Study 1, n=15), with different saline concentrations (normal saline 0.9%; hypertonic saline 3% on 2 days; and hypertonic saline 3, 4 and 5%, sequentially) (Study 2, n=14) and with pretreatment with either salbutamol or placebo (Study 3, n=10). The latter two studies were double-blind. Sputum cells were dispersed with dithiothreitol, and the cell suspension was used to perform total cell counts and to prepare cytospins for differential cell counts. We compared suc- cess rate, cell counts, subject discomfort and percentage fall in forced expiratory vol- ume in one second (FEV1) during the procedures. All sputum examinations were performed blind to the clinical procedures. The success rates and the cell counts of the specimens obtained with the two ultra- sonic nebulizers were not different, whilst general discomfort was proportional to the saline output of the nebulizer. Induction of sputum by hypertonic saline was more successful than normal saline, but more disagreeable to the subjects. Induction with saline 3% on two days was only successful in 6 of 14 subjects. Pretreatment with salbutamol inhibited the development of significant airway constriction in asth- matic subjects. Sputum cell counts were not affected by the tonicity of the saline or by salbutamol. We conclude that sputum induction is more likely to be successful when per- formed with an ultrasonic nebulizer and hypertonic saline, and that cell counts are unaffected. Pretreatment with salbutamol can inhibit bronchoconstriction and does not alter the cell count.