Eucapnic Voluntary Hyperventilation to Detect Exercise-Induced Bronchoconstriction in Cystic Fibrosis.

BACKGROUND: Exercise-induced bronchoconstriction (EIB) has not been well studied in cystic fibrosis (CF), and eucapnic voluntary hyperventilation (EVH) testing has not been used as an objective assessment of EIB in CF to date. METHODS: A prospective cohort pilot study was completed where standard EVH testing was completed by 10 CF patients with forced expiratory volume in 1 s (FEV1) ≥70% of predicted. All patients also completed a cardiopulmonary exercise test (CPET) with pre- and post-CPET spirometry as a comparative method of detecting EIB. RESULTS: No adverse events occurred with EVH testing. A total of 20% (2/10) patients were diagnosed with EIB by means of EVH. Both patients had clinical symptoms consistent with EIB. No patient had a CPET-based exercise challenge consistent with EIB. CONCLUSIONS: EVH testing was safe and effective in the objective assessment for EIB in patients with CF who had well-preserved lung function. It may be a more sensitive method of detecting EIB then exercise challenge.

Vocal cord dysfunction: beyond severe asthma.

BACKGROUND: Vocal cord dysfunction (VCD) is the abnormal adduction of the vocal cords during inspiration causing extrathoracic airway obstruction. VCD has been described as a confounder of severe asthma. The influence of VCD among less severe asthmatics has not been previously defined. METHODS: We retrospectively reviewed the medical records of 59 patients with pulmonologist-diagnosed asthma who were referred for videolaryngostroboscopy (VLS) testing from 2006 to 2007. RESULTS: A total of 44 patients had both asthma and VCD. 15 patients had asthma without concomitant VCD. Females were predominant in both groups. Overall, the majority of patients referred for VLS testing had mild-to-moderate asthma (78%) and 72% of these patients had VCD. Few patients from either group had "classic" VCD symptoms of stridor or hoarseness. Gastroesophageal reflux disease (GERD) and rhinitis were common in both groups. CONCLUSIONS: Vocal cord dysfunction occurs across the spectrum of asthma severity. There was a lack of previously described "classic" VCD symptoms among asthmatics. Symptoms were diverse and not easily distinguished from common symptoms of asthma, highlighting the need for a high index of suspicion for VCD in patients with asthma. Failure to consider and diagnose VCD may result in misleading assumptions about asthma control, and result in unnecessary adjustments of asthma medications. The high prevalence of GERD raises the question of the role of acid reflux in the pathogenesis of VCD in asthmatics.

Airway inflammation in exercise-induced bronchospasm occurring in athletes without asthma.

Exercise-induced bronchospasm (EIB) occurs in athletes with and without asthma. Studies have suggested an inflammatory basis for EIB in asthmatics; however whether inflammation plays a similar role in EIB in athletes without asthma remains unclear. Our objective was to determine whether there is evidence of an inflammatory basis for exercise-induced bronchospasm occurring in non-asthmatic athletes. Ninety-six athletes without asthma from varsity college teams underwent eucapnic voluntary hyperventilation testing. Sputum was induced from subjects with hypertonic saline inhalation post-eucapnic voluntary hyperventilation testing and was analyzed with enzyme-linked immunosorbent assays for IL-5, IL-8, IL-13, cysteinyl-leukotrienes, prostaglandin E2, histamine, leukotriene B4, and thromboxane B2. In addition, inflammatory (neutrophils, lymphocytes, eosinophils, and macrophages) and epithelial cell counts in sputum were recorded. Multivariate regression modeling showed a significant correlation between concentrations of select inflammatory mediators after eucapnic voluntary hyperventilation testing and severity of EIB. Means of the log-transformed concentrations of inflammatory mediators in EIB-positive athletes were significantly higher post-eucapnic voluntary hyperventilation than in EIB-negative athletes. Similar findings were not demonstrated with inflammatory cells. Concentrations of inflammatory mediators are higher in EIB-positive athletes than in EIB-negative athletes without asthma after eucapnic voluntary hyperventilation testing. The severity of EIB in our cohort also is significantly correlated with increased concentrations of select inflammatory mediators suggesting a potential inflammatory basis for EIB in athletes without asthma.