It has been hypothesized that vocal cord dysfunction (VCD) occurs silently in patients who are hospitalized and have symptoms of acute asthma exacerbation. VCD can be detected noninvasively with the use of the recently developed technique of dynamic computed tomography (CT) of the larynx, according to analysis results published in the American Journal of Respiratory and Critical Care Medicine.

Investigators sought to evaluate the prevalence of VCD in patients with an acute asthma exacerbation who were recruited from the emergency department (ED) of a tertiary care hospital in Melbourne, Australia, and required hospitalization. A total of 34 consecutive patients were enrolled in the study. The mean patient age was 42.15±17.41; 28 participants were women and 6 participants were men.

Asthma severity was deemed to be moderate or severe in >80% of the patients. Following initial disease stabilization, dynamic CT of the larynx was performed as quickly as possible. No beta-agonist treatment was administered in the hour before the CT. All of the participants had a history of asthma. In 30 of the 34 patients, evaluable spirometry had been performed either before or after the exacerbation. Bronchodilator responses of >12% were reported in 57% of these patients.

Of the 34 participants, chronic asthma was considered severe in 21 of these individuals. In the year prior to the study, patients had a mean of 1.3 asthma exacerbations.


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Vocal cord diameter measurements were made, normalized to tracheal measurements, and then integrated into a diagnostic algorithm. Following the generation of patient curves and a comparison of these with standard curves, a VCD diagnosis was rendered if the patient curve was below a lower limit of normal curve during inspiration (or, alternatively, during both inspiration and expiration, but not during expiration only). Patients with and without VCD were compared via regression and nonparametric analyses.

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VCD was present in 17.7% of the patients during an acute asthma exacerbation. Of the 6 patients with VCD, 4 had evidence of coexisting asthma on spirometry (with bronchodilator responses of 12%, 16%, 18%, and 23%, respectively).

The investigators concluded that VCD may be a key feature of acute exacerbations that are considered to be caused by asthma. The use of dynamic CT of the larynx is a novel methodology for the diagnosis of VCD, which is especially applicable to individuals experiencing acute exacerbations. The technique is noninvasive and is associated with superior patient acceptance and comfort. Use of this imaging approach warrants further confirmation in additional settings.

Reference

Daley CP, Ruane LE, Leong P, et al. Vocal cord dysfunction in patients hospitalised with symptoms of acute asthma exacerbation [published online May 31, 2019]. Am J Respir Crit Care Med. doi:10.1164/rccm.201902-0396LE