Poster Session Abstracts

Introduction: Two new versions of the beta-sweat secretion test focus- ing on the defective CFTR-dependent beta-adrenergic pathway have been recently developed with claimed advantage of having sufficient sensitivity to quantify half CFTR function in heterozygous and in atypical CF and to measure efficacy of novel therapies. Discussion: Measurement of VDP using pediatric population and VI quantification using this technique correlates closely with LCI. 129Xe-MRI and LCI could detect differences between healthy and CF participants, while conventional spirometry could not. Thus, VDP could be a marker of early lung disease in CF and could provide a sensitive, radiation-free modality to monitor the progression and response to treatment in these patients. References: 1. Kirby M, et al. Radiology. 2012;265:600-10. Figure – A box plot diagram showing the distribution of FEV1 (dots), LCI (checks) and VDP (diagonal lines) in healthy and CF participants. Hori- zontal lines represent the median measured value; boxes represent inter- quartile range and error bars represent minimum and maximum values. Asterisks denote statistically significant differences (p<0.05); NS denotes no statistically significant difference. Xe-MRI is feasible in a 286 Poster Session Abstracts 2 Methods: Rates of water evaporation (kg water/hr/m ) and of volume of sweat droplets (nL/min) were measured in an apparently healthy female, 61 years, following originally reported protocols of evaporimetry and bub- ble test. Results: Cholinergic phases were normal (maximal evaporimetric response 5 min after intradermal injection of carbachol: 95.1 kg water/hr/m2 and volume rate of droplets obtained 10 min after methacholine injection: 1.8 nL/min). However beta-adrenergic (isoprenaline plus aminophylline) responses, evaluated in the presence of atropine to inhibit the prior cholin- ergic stimulation, were abolished (β-adrenergic to cholinergic ratio: 0 and 0.7% for evaporimetry and bubble test respectively), eliciting a diagnosis of CF. The results were confirmed by repeating each test at least twice. History of current medications possibly interfering with the pharmacolog- ical agents used during the tests revealed long-term (>12 years) treatment of a well-controlled primary angle closure glaucoma consisting of a daily topical use of beta-blocker carteol 2% (1 drop/left eye). There are no appar- ent symptoms of beta-blocker intoxication (heart rate: 66 beats per min, regular sinus rhythm, no asthma symptoms). Sweat chloride concentration determined after pilocarpine iontophoresis using a coulometric method was 24 mmol/L Cl-. Conclusions: The two new versions of the beta-sweat secretion test are very sensitive to quantify the beta-adrenergic contribution of the sweat secretion. Beta-blocker treatment, even at topical use, leads to false-positive results. Much attention should be paid to the use of current medications that may interfere with the pharmacological steps of the tests. Supported by the Belgian CF Foundation.