Effects of combined treatment with rhDNase and airflow oscillations on spinnability of cystic fibrosis sputum in vitro

Treatment with either rhDNase or high‐frequency oscillation has been shown to be effective in improving the physical and transport properties of airway secretions in cystic fibrosis (CF). The objects of this in vitro study was to examine whether combined treatment with oscillation and rhDNase results in greater change of CF sputum spinnability than either treatment by itself. Aliquots of sputum (0.4 g) from eight CF patients were subjected to the following protocols for 15 minutes and then followed for a total of 30 minutes: (1)incubation with 0.04 ml DNase 50 μg rhDNasenormal saline (10% dilution) at 37°C to achieve 5 μg DNase/g of sputum final concentration; (2)airflow oscillation at 27 Hz similar to the airflow magnitude produced by a commercial high‐frequency chest compression (HFCC) device; (3)negative control with no treatment; (4)positive (dilution) control, incubating with 10% saline by volume; (5)combination of DNase and oscillation, and (6)combination of saline and oscillation. For each protocol, sputum spinnability (in mm, mean ± SD) was measured by means of a filancemeter at baseline, 15, and 30 minutes. Treatment with DNase decreased spinnability significantly more than either saline or oscillation at 15 and 30 minutes (P < 0.02 and P < 0.04, respectively). Incubation with saline or oscillation of CF sputum for 15 and 30 minutes decreased spinnability significantly compared with control. The combination of DNase and oscillation decreased spinnability significantly more than treatment with DNase alone (3.74 ± 0.45 vs. 6.54 ± 0.73 at 15 minutes, P < 0.01). The combination of saline and oscillation over 15 minutes decreased spinnability similarly to the application of DNase alone over the same period of time (7.84 ± 1.91 ± 6.54 ± 0.73, respectively). These in vitro results demonstrate an optimal effect on sputum spinnability when DNase and oscillation are used concomitantly. This suggests that combining biochemical (rhDNase) and physical (HFCC) treatments in CF patients may provide greater benefits than treatment with one modality at a time. Pediatr Pulmonol. 1995; 20:78–82. © 1995 Wiley‐Liss, Inc.