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Treatment with recombinant human deoxyribonuclease I (rhDNase) is currently used as therapy for cystic fibrosis (CF) lung disease. Hypertonic saline (HS) acts as an expectorant promoting mucus secretion and augmenting the volume of sputum. We evaluated the individual and combined effects of HS and rhDNase in vitro on the viscoelasticity of CF sputum. Sputum samples were collected from nine CF patients to use for in vitro testing. Aliquots of CF sputum (0.20 to 0.40 g) were subjected to the following protocols: (1) negative control sample without any treatment; (2) positive control sample, adding 10% volume of normal saline (0.9% NaCl); (3) application of hypertonic saline (HS-3% NaCl); (4) combining approximately 100 nM concentration of rhDNase with protocols 2 and 3. The samples in protocols 2 through 4 were incubated for 30 min at 37 degrees C. For each protocol, CF sputum was analyzed at baseline and at 30 min for spinnability by filancemeter and viscoelasticity by magnetic microrheometry. Spinnability decreased for the sputum samples that were treated with rhDNase, in combination with either HS or normal saline. Treatment with HS alone and combined treatment with rhDNase and HS decreased log G* (the principal viscoelasticity index) to the same degree. Saline alone and rhDNase in normal saline both increased the predicted cough clearability of the sputum; however, the combined treatment with rhDNase and hypertonic saline had the best overall effect on cough clearability. The change in predicted mucociliary clearability, although greatest after HS, was not significant. These in vitro results suggest that combined treatment with rhDNase and HS should be evaluated further as a potential mucotropic approach to augment the clearance of purulent sputum in CF lung disease.

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 micrograms rhDNase/normal saline (10% dilution) at 37 degrees C to achieve 5 micrograms 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).(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

Mucolytic treatment with rhDNase is part of the current therapy for cystic fibrosis (CF) lung disease. The Flutter® valve, a device for enhancing airway mucus clearance, has recently been approved for use in CF patients. Exhalation through the Flutter® valve leads to oscillations of expiratory airflow, improving mucus viscoelasticity and stimulating clearance. The goal of our in vitro study was to evaluate the individual and combined effects of Flutter® valve oscillations and rhDNase treatment on the viscoelastic (rheological) properties of CF sputum. Sputum specimens were collected from 19 CF patients and subjected to the following protocols: (1) baseline sample with no treatment applied; (2) application of oscillations generated by airflow through the Flutter® valve; (3) incubation at 37°C for 30 min with 10% vol/wt rhDNase (Pulmozyme®) to achieve a final concentration of 2.5 μg/mL (∼100 nM); (4) combination of Flutter® valve oscillations and 10% vol/wt normal saline (0.9% NaCl); (5) combination of Flutter® valve oscillations and 10% vol/wt rhDNase at 2.5 μg/mL final concentration. For each protocol, the mucus rigidity index (log G* at 1 rad/s) was measured at baseline and at 30 min. Values are presented as mean ±SEM. The cough clearability index (CCI) was computed from measurements of mucus viscoelasticity, based on relationships established in model studies. Flutter® valve treatment alone did not result in a significant reduction in the rigidity of CF sputum (2.24 ± 0.13 vs. 2.11 ± 0.13, P = 0.19), nor did rhDNase (2.5 μg/mL) alone, although we have previously shown (Pediatr. Pulmonol. 1995; 20:78) that both of these treatments reduce sputum spinnability, which is more sensitive to molecular weight reduction. In comparison to individual treatments, combined treatment with Flutter® valve oscillations and rhDNase significantly reduced the mucus rigidity to 1.85 ± 0.19 from 2.24 ± 0.13 (P < 0.001), consequently increasing the predicted clearability of the sputum (from 1.09 ± 0.26 to 1.83 ± 0.48, P = 0.012). These in vitro results suggest that a combination of biochemical treatment (e.g., DNase) and mechanical oscillation may have a better therapeutic potential for mucus clearance in CF lung disease. Pediatr Pulmonol. 1998; 26:250–255. © 1998 Wiley‐Liss, Inc.