Controversies in the management of pulmonary disease due to cystic fibrosis

Use of aerosolized colistin sodium in cystic fibrosis patients awaiting lung transplantation

BACKGROUND

In patients with cystic fibrosis (CF) who are awaiting lung transplant, prolonged exposure to systemic antibiotics has frequently led to airway colonization with resistant isolates of Pseudomonas. This resistance limits the arsenal of effective antimicrobials available for infections after the initiation of immunosuppression and has been considered a theoretical deterrent to lung transplantation.

METHODS

Twenty CF transplant candidates with "pan-resistant" Pseudomonas received maintenance antibiotic therapy with aerosolized colistin sodium (75 mg b.i.d.), and intravenous antibiotics were eliminated. Ten other CF candidates did not use colistin sodium. Sputum cultures and antibiotic sensitivities were followed every 3-6 weeks.

RESULTS

All 20 candidates (100%) who used aerosolized colistin sodium became colonized with sensitive isolates of Pseudomonas in an average of 45.1+/-20.2 days. In contrast, only 3 of 10 CF transplant candidates (30%) who did not use colistin sodium later became colonized with sensitive isolates. The mean time to spontaneous emergence of sensitive organisms was 144.6+/-48.0 days in candidates who did not use colistin sodium and was significantly longer than in the candidates who used colistin sodium (P=0.007). The occurrence of redeveloping sensitive isolates of Pseudomonas was significantly greater in the candidates who used colistin sodium (P<0.05). Of the candidates who used colistin sodium, six have been transplanted at our institution. In five of these six recipients (83.3%) bacterial cultures taken from the explanted lungs continued to demonstrate sensitive organisms.

CONCLUSION

Aerosolized colistin sodium may be a useful therapy to promote emergence of sensitive microbes in CF candidates with pan-resistant isolates of Pseudomonas.

Nasal mucociliary transport and ciliary ultrastructure in cystic fibrosis. A comparative study with healthy volunteers

Cystic fibrosis (CF) is a deadly hereditary disease that produces an abnormally thick, viscous and abundant secretion in the respiratory tract. This secretion in turn leads to the development of recurrent respiratory infections and irreversible lung damage. We have studied nasal mucociliary transport by means of an isotopic technique in 12 patients with CF and in 12 healthy volunteers. Nasal mucociliary transport was repeated at 12-18 months in the patients. In five randomly selected patients ciliary ultrastructure was studied. The velocity of nasal mucociliary transport was significantly slower than in healthy persons (P < 0.001) and no significant differences were observed in both studies (P < 0.05). No significant differences were either observed in the CF group between the homo- and heterozygotes (P < 0.5), or in those six patients infected by Pseudomonas aeruginosa (P < 0.05). Ciliary ultrastructure was normal in one patient. In another patient the sample showed no cilia, while the remaining three exhibited changes similar to those observed in chronic respiratory infections: supernumerary peripheral tubules, ciliary disorientation and ciliary complexes.

A comparison of bronchial drainage treatments in cystic fibrosis

We compared standard chest physical therapy and postural drainage (CPT/PD) with a new airway clearance therapy called high-frequency chest wall oscillation (HFCWO) in a group of stable cystic fibrosis (CF) patients. In this crossover trial, 29 CF patients (15 males, 14 females), aged 7-47 years that met the inclusion criteria were randomly assigned to alternate CPT/PD and HFCWO, on a daily basis, over a 4 day period. Each patient received 2 days of each form of therapy; treatment frequency and the length of treatment were the same for both techniques. Expectorated secretions were collected during each 30 minute therapy session and for 15 minutes following treatment. The wet and dry weights of collected secretions were determined gravimetrically, and the therapy methods were compared. Significantly more sputum was expectorated during HFCWO than during CPT/PD as determined by both the wet (P < 0.001) and the dry (P < 0.01) measurements. This study suggests that HFCWO is at least as effective as manual CPT/PD in clearing secretions from the airways in patients with cystic fibrosis.

Immunofluorescence studies of lung tissue in cystic fibrosis

Previous studies have suggested that immune mechanisms contribute to lung injury in cystic fibrosis (CF); however, there have been no comprehensive studies of immunofluorescent staining patterns in CF lung tissue. We performed immunofluorescence (IF) studies for immunoglobulins, C3, and fibrinogen on autopsy frozen lung tissue from 21 CF patients. Results were compared with lung findings in patients without CF. In CF-derived lung tissue fibrinogen was ubiquitous along the alveolar wall, alveolar space, and interstitium. Free immunoglobulin G (IgG) and IgA coated the alveolar surface segmentally in 14 and 6 cases, respectively. Unequivocal interstitial deposits were infrequent and IgM was present in blood vessels in one patient only. Intra-alveolar and interstitial inflammatory cells demonstrated cytoplasmic IgG, IgA, and IgM, respectively, in 18, 14, and 6 patients. C3 was seen only segmentally along the alveolar wall in two patients and in blood vessels in one. Antinuclear antibody (ANA) staining of interstitial cells for C3 and immunoglobulins was seen in five patients, four of whom had interstitial pneumonitis. Insignificant amounts of alveolar or interstitial fibrinogen and immunoglobulins in inflammatory cells were seen in controls in the absence of lung inflammation. The IF patterns were similar in the inflammatory lesions of CF and control specimens. The IF patterns observed in CF lung tissue are consistent with nonspecific vascular leakage and chronic inflammation with little evidence of immune complex deposition in the interstitium or blood vessels. This study confirms previous reports of ANA activity in CF patients, although the significance of this finding is unknown.

Effect of positive expiratory pressure breathing in patients with cystic fibrosis

The effect of positive expiratory pressure breathing, alone and in combination with coughing, was investigated in eight patients with cystic fibrosis. Functional residual capacity and total lung capacity was measured with a body plethysmograph before, during, and immediately after breathing with expiratory pressure of 5 and 15 cm H2O, and after a coughing period. The positive expiratory pressure breathing was carried out five times for two minutes with a two minute interval between each period. Mucus transport was measured in a peripheral lung region and over the whole lung by a radioactive aerosol tracer technique. Clearance measurements were carried out continuously during positive expiratory pressure breathing and during a control period. Two minutes' breathing with an expiratory pressure of 5 and 15 cm H2O caused an increase in mean (SEM) functional residual capacity from 2.6 (0.1) to 3.6 (0.3) and 4.4 (0.5) 1 and an increase in total lung capacity from 5.1 (0.2) to 5.9 (0.3) and 6.9 (0.4) 1. Lung volumes were higher during breathing with an expiratory pressure of 15 cm H2O than with 5 cm H2O; both returned to baseline values immediately after positive expiratory pressure breathing. Spontaneous mucus clearance and mucus clearance by coughing were not influenced by positive expiratory pressure breathing at either expiratory pressure. Thus in patients with cystic fibrosis positive expiratory pressure breathing increases lung volumes in relation to the expiratory pressure imposed; these changes in lung volume did not, however, lead to an improvement of mucus transport.