Ann Thorac Surg 2006;82:2268-2270
© 2006 The Society of Thoracic Surgeons
Case Reports
Treatment of Bronchomalacia in Cystic Fibrosis by Silicone Stent
Georg N. Herlitz, MDa,
David I. Sternberg, MDa,
Regina Palazzo, MDb,
Selim Arcasoy, MDc,
Joshua R. Sonett, MDa,*
a Department of Surgery, Division of Cardiothoracic Surgery, Columbia University College of Physicians and Surgeons, New York, New York
b Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
c Department of Medicine, Division of Pulmonary, Allergy & Critical Care, Columbia University College of Physicians and Surgeons, New York, New York
Accepted for publication May 2, 2006.
* Address correspondence to Dr Sonett, Department of Surgery, Division of Cardiothoracic Surgery, New York Presbyterian Hospital/Columbia, PH Room 104, 14th Floor, 622 West 168th St, New York, NY 10032. (Email: js2106{at}columbia.edu).
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Abstract
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We report the case of a 15-year-old girl with cystic fibrosis and rapidly declining pulmonary function tests who was found to have collapse of the left main bronchus from bronchomalacia. She underwent successful deployment of an expandable silicone stent in the collapsed bronchus, after which her pulmonary function test results and her clinical picture markedly improved, obviating the need for immediate transplantation. A literature review yielded no prior reports of bronchomalacia in a cystic fibrosis patient being treated with a silicone stent. This case shows that a simple, effective treatment is possible for one cause of obstructive pulmonary function in cystic fibrosis.
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Introduction
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Cystic fibrosis (CF) is the most common lethal genetic disorder in Caucasian populations [1]. This autosomal recessive disorder is caused by a defective chloride transporter and leads to an excessively thick mucus in the lungs, which drains poorly and is difficult to clear [2]. Although other organ systems are involved in this disease, the pulmonary complications are the most serious ones, causing about 80% of all deaths from CF in the United States. In these patients, mucus plugging causes both acute and chronic bacterial infection that damages the airway, leading to bronchiectasis, which is an irreversible dilatation and destruction of the bronchial walls. Progressive respiratory failure generally follows [3].
We report a case involving a successful treatment made with a removable, expandable silicone stent for bronchomalacia, involving the left main stem bronchus of a 15-year-old girl with CF and rapidly declining respiratory status. After stent deployment, both pulmonary function test results and the clinical status markedly improved, obviating the need for immediate transplantation.
The patient was diagnosed with CF by screening examinations when she was 8 weeks old. Her first exacerbation occurred 8 years later and she began treatment with bronchodilators and inhaled tobramycin, which stabilized her until age 15. At 15 years of age she began experiencing shortness of breath and was treated with increasing doses of antibiotics.
Spirometry testing at 14 years of age had shown a forced expiratory volume in 1 second (FEV1) of 1.84 L, which was 79% of the predicted value. Eleven months later, spirometry revealed an obstructive pattern with a FEV1 of 0.84 L, which was 34% of the predicted value. Physical examination demonstrated decreased left-sided breath sounds. Chest roentgenogram demonstrated bilateral changes consistent with CF, but no acute or focal process, and flexible bronchoscopy revealed collapse of the left main stem bronchus (Fig 1).
A removable silicone stent (Ployflex Airway Stent, Boston Scientific, Natick, MA) was placed in the left main stem bronchus through a rigid bronchoscope. Flexible bronchoscopy confirmed excellent proximal and distal positioning.
After stent deployment, the patient’s dyspnea resolved. Repeat pulmonary function testing showed a FEV1 of 1.20 L. Six months after stent deployment the patient continued to do well clinically. There were no further instances of the left mainstem airway collapse or mucus plugging. Repeat pulmonary function testing showed a FEV1 of 1.38 L, and bronchoscopy demonstrated only minimal swelling in the surrounding bronchus (Fig 2). There were no infectious complications due to stent deployment. At 6 months, repeat culture demonstrated no change in the lung flora.
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Comment
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Cystic fibrosis occurs in about 1 in 3,200 live births among Caucasians, and it is estimated that 2% to 4% of the white population are heterozygous carriers of a dysfunctional copy of the cystic fibrosis transmembrane regulator, which is the gene responsible for CF.
Severity of signs and symptoms correlates loosely with laboratory tests and the severity of the genetic lesion. Indeed, in one study, more than 40% of patients with clinical symptoms had no discernible mutations, despite extensive investigation [4].
The most prominent pulmonary sequelae are excessively thick mucous secretions, recurrent bacterial infections, and alteration of the structural architecture of the airway walls. The reduced level of chloride in the airway containing the mucus is believed to reduce sodium concentration in the airway, dehydrating the milieu, and producing excessively viscous mucous secretions. In addition, it is believed that recruited neutrophils function poorly because of the requirement for chloride in the respiratory burst [5]. In consequence, CF patients are prone to repeated bacterial infections in the lungs. As the infections persist, the body recruits greater numbers of neutrophils to fight the infection, accounting for the grossly purulent secretions characteristic of CF histology. With breakdown, neutrophils release elastase and other proteases, and these biochemicals degrade various connective tissues [6]. The repeated exposure of the airways to high levels of elastase causes long-term damage and remodeling, resulting in the characteristic bronchiectasis. Consequently the bronchiectatic loss of airway elasticity produces an obstructive pattern on the pulmonary function testing that is most notably a decreased FEV1 and FEV1: forced vital capacity ratio.
Bronchomalacia, or large airway collapse, is only rarely reported as a sequela of CF. However, the chronic connective tissue damage characteristic of CF would be expected to produce increased rates of bronchomalacia. Furthermore, bronchomalacia will cause changes in pulmonary function testing that are similar to those changes seen in more common, but less treatable, sequelae such as bronchiectasis and mucus plugging. For this reason, bronchomalacia may sometimes be overlooked in the CF patient with obstructive pattern pulmonary function testing. In general, stent use in benign disease should be avoided because of the long-term sequelae of bronchial irritation, tissue in growth, and bacterial overgrowth [7]. For this reason an expandable and easily removable silastic nonmetallic stent was chosen for the primary intervention. In addition, the improved internal to external diameter of this expandable silastic stent, as opposed to the older rigid silicone stents, may have facilitated the surprising lack of mucous plugging or superinfection.
In conclusion, the authors were unable to find any published reports of large airway collapse in CF being treated with a pulmonary stent. We have shown that bronchomalacia in CF patients can be successfully treated with a silicone stent, without secondary complications of superinfection or mucous plugging. The ease and efficacy of this treatment may warrant a higher index of suspicion for airway collapse as a cause of dyspnea and obstructive-pattern pulmonary function tests in CF patients.
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References
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- Kumar V, Abbas A, Fausto N. Robbins and Cotran pathologic basis of disease. London: Elsevier; 2005. pp. 489-490.
- Rowe SM, Miller S, Sorscher EJ. Cystic fibrosis N Engl J Med 2005;352:1992.[Free Full Text]
- Bals R, Weiner DJ, Wilson JM. The innate immune system in cystic fibrosis lung disease J Clin Invest 1999;103:303.[Medline]
- Groman JD, Karczeski B, Sheridan M, Robinson TE, Fallin, MD, Cutting GR. Phenotypic and genetic characterization of patients with features of "nonclassic" forms of cystic fibrosis J Pediatr 2005;146:675.[Medline]
- Tager AM, Wu JY, Vermeulen MW. The effect of chloride concentration on human neutrophil functions: potential relevance to cystic fibrosis Am J Respir Cell Mol Biol 1998;19:643.[Abstract/Free Full Text]
- Kumar V, Abbas A, Fausto N. Robbins and Cotran pathologic basis of disease. London: Elsevier; 2005. pp. 72.
- Sonett JR, Conte JV, Orens J, Krasna M. Endobronchial wire mesh stents in benign disease: a word of caution. 1997Chest 1997 Annual Meeting, New Orleans, LA, Oct 26–30.
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Abstract
Introduction
