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Communications to the Editor |

Tracheobronchomalacia : A Cause of Flow Oscillations on the Flow-Volume Loop FREE TO VIEW

Eduardo Garcia-Pachon, MD
Author and Funding Information

Hospital Vega Baja Orihuela-Alicante, Spain

Correspondence to: Eduardo Garcia-Pachon, MD, Department of Internal Medicine, Hospital Vega Baja, Orihuela-Alicante, E-03314 Spain



Chest. 2000;118(5):1519. doi:10.1378/chest.118.5.1519
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To the Editor:

The visual inspection of the flow-volume loop can reveal the presence of flow oscillations. Flow oscillations are defined as a reproducible sequence of alternating decelerations and accelerations of flow.1In a large retrospective survey2 of 2,800 flow-volume loops, the incidence of flow oscillations was of 1.4%. These oscillations can be due to a variety of causes, such as obstructive sleep apnea syndrome, structural or functional disorders of the larynx, or neuromuscular diseases,1 but tracheobronchomalacia has not been mentioned.

A 58-year-old man with a diagnosis of COPD with chronic cough and exertional dyspnea was referred to the Respiratory Medicine Division because of a pulmonary nodule. The patient did not have symptoms of sleep disorders or neuromuscular disease. At fiberoptic bronchoscopy, the larynx was normal, but the trachea and main bronchus completely collapsed even during quiet expiration. Thoracic CT revealed a 1.5-cm nodule, and images obtained during expiration demonstrated the collapse of the trachea. Spirometry showed FVC of 3.96 L (118% of reference value) and FEV1 of 2.28 L (84%); the volume-time curve did not have morphologic alterations, but the visual inspection of the flow-volume loop revealed reproducible flow oscillations on the expiratory curve.

The prevalence of tracheobronchomalacia is relatively low: 1% and 4.5% in two large series of bronchoscopies.3 The principal symptom is chronic dyspnea, but attacks like those in asthma are seldom seen, and response to bronchodilator treatment is scanty.3 In patients with tracheobronchomalacia, a typical notch (can be one or more) in the volume-time curve of the spirogram has been reported3; this finding was not found in the patient described here. The notch is considered to reflect a sudden diminution of flow at the beginning of the expiration when the airway collapses. Nevertheless, alterations on the flow-volume loop have not been reported.

The finding of flow oscillations on the flow-volume loop should instigate extensive investigations primarily directed at the upper airway and its surrounding musculature.1 In view of the case described here, tracheobronchomalacia should be considered among the possible causes of flow oscillations.

Vincken, WG, Cosio, MG (1989) Flow oscillations on the flow-volume loop: clinical and physiological implications.Eur Respir J2,543-549. [PubMed]
 
Vincken, W, Cosio, MG Flow oscillations on the flow-volume loop: a nonspecific indicator of upper airway dysfunction.Bull Eur Physiopathol Respir1985;21,559-567. [PubMed]
 
Nuutinen, J Acquired tracheobronchomalacia.Eur J Respir Dis1982;63,380-387. [PubMed]
 

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References

Vincken, WG, Cosio, MG (1989) Flow oscillations on the flow-volume loop: clinical and physiological implications.Eur Respir J2,543-549. [PubMed]
 
Vincken, W, Cosio, MG Flow oscillations on the flow-volume loop: a nonspecific indicator of upper airway dysfunction.Bull Eur Physiopathol Respir1985;21,559-567. [PubMed]
 
Nuutinen, J Acquired tracheobronchomalacia.Eur J Respir Dis1982;63,380-387. [PubMed]
 
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