[Inducible laryngeal obstruction vs. bronchial asthma]

Abstract

Inducible Laryngeal Obstruction vs. Bronchial -Asthma Background: Inducible laryngeal obstructions (ILO) represent paroxysmal and sometimes severe dyspnea caused by different factors. Symptomatically ILO resembles bronchial asthma and is therefore often misdiagnosed. In the following 3 cases regarding a special type of ILO, the exercise induced laryngeal obstruction (EILO) will be presented. It will also be demonstrated, how EILO can be diagnosed and differentiated from bronchial asthma.

Method: Laryngeal symptoms were provoked by spiroergometry (treadmill or bicycle) and inspected by laryngoscopy.

Results: Symptoms could be provoked in all of the 3 patients by either treadmill or bicycle spiroergometry. When a stridor occurred, usually 1.5-2 min after the anaerobe threshold had been exceeded, spiroergometry showed a decline or plateau of carbon dioxide emission and oxygen intake. Laryngoscopy revealed adduction of the vocal cords during inspiration occa-sionally with a collapse of supraglottic structures towards the endolarynx.

Discussion: This article is the first to report that EILO can be distinctly depicted by spiroergometry. The decline or plateau in oxygen and carbon dioxide curves in coordination with the onset of stridor, approximately 1.5-2 min after the anaerobe threshold had been exceeded, was found to be reproducible in all cases. Furthermore, endoscopy immediately following peak exhaustion represents a practical tool for the identification of EILO.·