W De Backer

University of Antwerp, Antwerpen, Flanders, Belgium

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Publications (212)718.21 Total impact

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    ABSTRACT: In two subjects with a unilateral diaphragmatic paralysis and complaints of dyspnea, a completely different treatment approach was chosen despite similar anatomical and physiological abnormalities. These decisions were supported by the results generated by Functional Respiratory Imaging (FRI). FRI was able to generate functional information with respect to lobar ventilation and local drug deposition. In one subject, it was found that some lobes were poorly ventilated and drug deposition simulation showed that some regions were undertreated. This subject underwent a diaphragm plication to restore the ventilation. In the other subject, it was found that all lobes were still ventilated. A conservative approach with regular follow-up was chosen to wait for spontaneous recovery of the diaphragmatic function. Both subjects improved subjectively and objectively. These cases demonstrate how novel medical imaging techniques such as FRI can be used to personalize respiratory treatment in subjects with unilateral diaphragmatic paralysis.
    Respiratory care. 12/2013;
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    J Verbraecken, W De Backer, P Levy
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    ABSTRACT: EDITORIAL The first ERS School Course on Sleep Medicine was held in Antwerp (Belgium) on November 10–12, 2005, as an initiative from the ERS School and the Sleep and Control of Breathing Group (4.2) of the Clinical Physiology and Integrative Biology Assembly. This course was a 3-day programme designed for anyone who wanted to develop a better understanding of several important areas in sleep medicine. Each topic was addressed by a recognised expert in that specific field. Presentations included a 30-minute formal pre-sentation of the material and a question-and-answer session to ensure faculty–participant interaction. The discussions were always lively and the subjects covered an entire range of sleep and sleep-disordered breathing.
    Breathe 11/2013; 2006(2(3)):213-214.
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    ABSTRACT: We read with great interest the article by Dr. Phillips and col-leagues that reported on the 1-month results of a randomized crossover trial comparing the health effects of two treatment mo-dalities for the management of patients with moderate-to-severe obstructive sleep apnea (OSA): continuous positive airway pres-sure (CPAP) treatment versus therapy with an oral appliance that reduces upper airway collapse by advancing the mandible (OA m) (1). The results showed that health outcomes were sim-ilar after treatment with OA m as compared with CPAP. These important findings are indeed likely to be explained by the greater efficacy of CPAP, in terms of a lower residual apnea– hypopnea index as compared with OA m , being offset by inferior CPAP compliance relative to OA m compliance, possibly resulting in equal overall effectiveness. In their conclusion, the authors advocate the need for long-term comparative effectiveness stud-ies between CPAP and OA m that include objectively measured compliance to better define treatment strategies for patients with OSA. In Dr. White's accompanying editorial (2), he attributes the lack of objective compliance data for the OA m therapy in the trial by Dr. Phillips and colleagues to the difficulty in obtaining objective usage data for the OA m . In addition, Dr. White con-tends that a method to quantify OA m effectiveness is needed on the basis of the well-documented experience that not all patients responded similarly to OA m therapy, resulting in a residual apnea– hypopnea index greater than 20 or 30 per hour of sleep in a subset of the participants (1, 2). This method should allow physicians to determine the efficacy of OA m before fabrication of the device for each individual patient. We would like to emphasize the following: first, as the authors rightly point out (1, 2), objective assessment of compliance with both CPAP and OA m is mandatory to assess the true night-to-night residual disease. Recently, we were able to report on the safety and feasibility of accurate, objective measurement of OA m compliance in a 3-month prospective clinical trial using an em-bedded microsensor thermometer in the OA m of 51 consecutive patients with OSA (3). Our one-year results confirm the safety and feasibility of this method to obtain long-term data regarding objective compliance during oral appliance therapy for OSA (4). Indeed, measurement of objective OA m compliance allows for calculation of the mean disease alleviation, which is the product of objective compliance and therapeutic efficacy, as a measure of the overall therapeutic effectiveness (3). Second, we underline the need for prospective identification of favorable candidates for OA m therapy in the treatment of OSA. As mentioned by Dr. White (2), one should avoid fabri-cating and testing the OA m in each patient before confirming that OA m therapy is appropriate for a particular patient. Some of the many possible techniques for mimicking OA m wear are to perform a mandibular titration sleep study with a remotely con-trolled mandibular positioner (5) or to use a simulation bite approach during drug-induced sleep endoscopy (6). Both the remotely controlled mandibular positioner and the simulation bite approach have the clear advantage of providing a repro-ducible mandibular advancement maneuver and adequately accounting for the given vertical opening of a particular OA m . Both devices can be applied during awake endoscopy or imaging studies as well as during drug-induced sleep endos-copy or overnight sleep studies (5–7). In conclusion, we would like to join Dr. Phillips and colleagues in recommending long-term research on the comparative effec-tiveness of different treatment modalities for the management of OSA. We particularly emphasize the necessity to obtain objec-tive measurement of OA m use for all future clinical trials evaluat-ing OA m therapy. Improving the ability to predict OA m outcome prospectively in the individual patient should be another im-portant goal of the research agenda.
    American Journal of Respiratory and Critical Care Medicine 11/2013; 188(9):1162. · 11.04 Impact Factor
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    Sleep-Wake Research in the Netherlands 2004. 10/2013; 15:103-106.
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    Neuron 10/2013; 7(9):275-277. · 15.77 Impact Factor
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    Sleep-Wake Research in the Netherlands 2004. 10/2013; 15:107-110.
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    Sleep-Wake Research in the Netherlands 2004. 10/2013; 15:111-114.
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    10/2013: pages 103-105; , ISBN: 90-73675-12-X
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    10/2013: pages 99-102; , ISBN: 90-73675-12-X
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    Bloevaten Hart Longen. 10/2013; 7(9):305-306.
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    Vaisseaux Coeur Poumons. 10/2013; 7(9):305-306.
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    Vaisseaux Coeur Poumons. 10/2013; 7(6):183-184.
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    Bloedvaten Hart Longen. 10/2013; 7(6):183-184.
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    ABSTRACT: INTRODUCTION Nasal CPAP (continuous positive airway pressure) is the preferred treatment for obstructive sleep apnea and mechanical splinting of the upper airway has traditionally been indicated the mechanism of action. Since CPAP can influence lung inflation during the daytime, this could also lead to an improvement of daytime gas exchange. We also wondered whether CPAP therapy could influence the apnea severity of the underlying obstructive sleep apnea syndrome. To explore this hypothesis, we evaluated arterial blood gases in sleep apnea patients after at least one month of CPAP therapy. We also looked at residual effects of CPAP on nocturnal breathing pattern during one night CPAP withdrawal after one year CPAP therapy in a large series of (predominantly obstructive) sleep apnea patients. PATIENTS AND METHODS Gas exchange study 132 patients treated with CPAP were evaluated with arterial blood gas analysis after at least one month of treatment. The characteristics of the patients are shown in Table 1. Measurements were performed in the afternoon before treat-ment, while follow up measurements took place in the morning. Arterial blood gases were processed immediately in an analyzer. The alveolar oxygen tension was calculated according to the ideal alveolar gas equation 1 , which was necessary to derive the alveolo-arterial oxygen difference.
    10/2013: pages 135-137; , ISBN: ISBN 90-76906-22-X
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    ABSTRACT: Fluticasone furoate/vilanterol trifenatate (FF/VI) is a once-daily (OD) inhaled corticosteroid/long-acting β2-agonist combination in development for chronic obstructive pulmonary disease (COPD) treatment. We compared the efficacy and safety of FF/VI versus fluticasone propionate/salmeterol (FP/SAL) twice-daily (BD) over 12 weeks.Moderate to very severe COPD patients received FF/VI 100/25 μg OD in the morning (N=266) or FP/SAL 500/50 μg BD (N=262). Primary endpoint: change from baseline in 0-24 h weighted mean forced expiratory volume in 1 s (wmFEV1) at 12 weeks. Additional endpoints included: time to 100 mL improvement from baseline on day 1; change from baseline in St George's Respiratory Questionnaire (SGRQ). Safety was also assessed.wmFEV1 (mean, 130 mL) was greater and time to 100 mL improvement shorter (median, 16 min) with FF/VI than FP/SAL (mean [wm], 108 mL; median, 28 min). Health status (SGRQ total score) improved in both groups (FF/VI, -4.3 units; FP/SAL, -3.0 units). Differences between treatments were not statistically significant. Six patients in the FF/VI (2%) and 3 in the FP/SAL (1%) arm experienced serious adverse events, none of which were considered to be drug-related.Improvements in lung function and health status were not significantly different between FF/VI 100/25 μg OD and FP/SAL 500/50 μg BD; there was no apparent differentiation between the safety profiles of either therapy.
    European Respiratory Journal 10/2013; · 6.36 Impact Factor
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    ABSTRACT: Sleep-disordered breathing (SDB) is common among overweight and obese children. It is a risk factor for several health complications, including cardiovascular disease. Inflammatory processes leading to endothelial dysfunction are a possible mechanism linking SDB and cardiovascular disease. Elevated C-reactive protein (CRP) is a risk factor for cardiovascular disease and is independently correlated with obstructive sleep apnea syndrome (OSAS) in adults. Our goal is to evaluate the relationship between CRP and OSAS in overweight and obese children and adolescents. One hundred and twenty children were prospectively studied (85 without OSAS, 20 mild OSAS, 15 moderate-to-severe OSAS). All subjects underwent polysomnography, and a blood sample was taken to determine CRP levels. No significant differences were found in CRP between subjects with or without OSAS, and no correlations were found between CRP and OSAS severity, despite the relationship between CRP and BMI (r = 0.21, p = 0.015) and between CRP and fat mass (r = 0.31, p < 0.001). These results suggest that CRP levels are correlated with the level of obesity but are not influenced by SDB in obese children and adolescents; hence, this in contrast to that in adult population.
    Sleep And Breathing 09/2013; · 2.26 Impact Factor
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    ABSTRACT: ABSTRACT BACKGROUND Assessment of the overall therapeutic effectiveness of oral appliance therapy can only be realized through objectively measured compliance. The objective is to assess objectively measured compliance during oral appliance therapy at 1-year follow-up, and to compare these objective compliance data with self-reported use. METHODS 51 eligible patients were enrolled in this 1-year prospective clinical study (61% male; age: 49 ± 10 years; AHI: 18.0 ± 11.9/hour sleep; BMI: 26.6 ± 4.1 kg/m2). Objective compliance during oral appliance therapy at 1-year follow-up was assessed using a microsensor thermometer (TheraMon®, Handelsagentur Gschladt, Austria). Subjective compliance was assessed using self-report. Patients with a mean objectively measured use of ≥ 4 hours/night on 70% of nights monitored were considered regular users. The mean disease alleviation was calculated as a measure of overall therapeutic effectiveness. RESULTS High agreement between objective and subjective compliance data at 1-year follow-up was reported (ICC = 0.8; 95% CI 0.5; 0.9), showing a mean subjective overestimation of 30 minutes (p = 0.02; 95% CI -3.1; 1.9). The discontinuation rate at 1-year follow-up was 9.8%. The objective mean use rate was 6.4 ± 1.7 hours per night at 1-year follow-up in continuing users, with a regular use rate of 83%. The mean disease alleviation was 54.8%. CONCLUSIONS The present study is the first report on the 1-year results of objectively measured compliance during oral appliance therapy. In addition, a high agreement between objective and subjective compliance data was reported, with a mean subjective overestimation of 30 minutes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT01284881.
    Chest 08/2013; · 5.85 Impact Factor
  • W De Backer
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    ABSTRACT: Obstructive sleep apnea/hypopnea syndrome (OSAHS) is characterized by recurrent episodes of partial or complete upper airway collapse during sleep that is highlighted by a reduction in, or complete cessation of, airflow despite documented on going inspiratory efforts. Due to the lack of adequate alveolar ventilation that results from the upper airway narrowing, oxygen saturation may drop and partial pressure of CO2 may occasionally increase. The events are mostly terminated by arousals. Clinical consequences are excessive daytime sleepiness related to the sleep disruption. Minimal diagnostic criteria have been defined for OSAHS. Patients should have excessive daytime sleepiness that can not be better explained by other factors, or experience two or more of the following symptoms, again that are not better explained by other factors: choking or gasping during sleep; recurrent awakenings from sleep; un-refreshing sleep; daytime fatigue; and impaired concentration. All patients should have more than five obstructed breathing events per hour during sleep. An obstructive apnea or hypopnoea can be defined as an event that lasts for ≥10 s and is characterized by an absence or a decrease from baseline in the amplitude of a valid measure of breathing during sleep that either reaches >50% with an oxygen desaturation of 3% or an arousal (alternatively a 30% reduction with 4% desaturation). The American Academy of Sleep Medicine (AASM) recommends these definitions. The Task Force of the AASM also states that there are common pathogenic mechanisms for obstructive apnea syndrome, central apnea syndrome, sleep hypoventilation syndrome and Cheyne-Stokes breathing. It was more preferable to discuss each of these separately; although, they could be placed under the common denominator of "sleep-disordered breathing syndrome". The definition of OSAHS using two components, daytime symptoms and breathing pattern disturbances during sleep, may suggest that there is a tight correlation between the two. However, unfortunately this is not the case. The breathing pattern abnormalities, mostly described by an Apnea/Hypopnoea Index (AHI), only weakly correlate with quantified measures of sleepiness, such as the Epworth Sleepiness Scale (ESS). This probably means that interindividual sensitivity, with some individuals coping better with sleep fragmentation than others, does compromise the relationship between the AHI and daytime sleepiness scores. In addition, epidemiological studies show a broad range of sleepiness in the general population. Obviously, epidemiological studies investigating the prevalence of OSAHS are all biased by the lack of a uniform definition. The prevalence of an AHI of >5 events·h-1 in a general population (without taking into account symptoms of sleepiness) has previously been estimated to be 24% in a male population. When symptoms of sleepiness were also taken into account, the prevalence decreased to 4% in males and 2% in females.
    Panminerva medica 06/2013; 55(2):191-5. · 0.98 Impact Factor
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    ABSTRACT: Background: Inhaled formulations using extrafine particles of long-acting β2-agonists and corticosteroids were developed to optimize asthma treatment. Findings that these combinations reach and treat smaller airways more effectively are predominantly based on general non-specific outcomes with little information on regional characteristics. Objectives: This study aims to assess long-term effects of extrafine beclomethasone/formoterol on small airways of asthmatic patients using novel functional imaging methods. Methods: Twenty-four stable asthma patients were subdivided into three groups (steroid naive, n = 7; partially controlled, n = 6; well controlled, n = 11). Current treatment was switched to a fixed combination of extrafine beclomethasone/formoterol (Foster®; Chiesi Pharmaceuticals, Parma, Italy). Patients underwent lung function evaluation and thorax high-resolution computerized tomography (HRCT) scan. Local airway resistance was obtained from computational fluid dynamics (CFD). Results: After 6 months, the entire population showed improvement in pre-bronchodilation imaging parameters, including small airway volume (p = 0.0007), resistance (p = 0.011), and asthma control score (p = 0.016). Changes in small airway volume correlated with changes in asthma control score (p = 0.004). Forced expiratory volume in 1 s (p = 0.044) and exhaled nitric oxide (p = 0.040) also improved. Functional imaging provided more detail and clinical relevance compared to lung function tests, especially in the well-controlled group where only functional imaging parameters showed significant improvement, while the correlation with asthma control score remained. Conclusions: Extrafine beclomethasone/formoterol results in a significant reduction of small airway obstruction, detectable by functional imaging (HRCT/CFD). Changes in imaging parameters correlated significantly with clinically relevant improvements. This indicates that functional imaging is a useful tool for sensitive assessment of changes in the respiratory system after asthma treatment.
    Respiration 04/2013; · 2.62 Impact Factor
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    ABSTRACT: Abstract Background: As the upper airway is the most important limiting factor for the deposition of inhalation medication in the lower airways, it is interesting to assess how its morphology varies between different postures. The goal of this study is to compare the upper airway morphology and functionality of healthy volunteers in the upright and supine positions during tidal nasal breathing and to search for baseline indicators for these changes. This is done by performing three-dimensional measurements on computed tomography (CT) and cone beam computed tomography (CBCT) scans. Methods: This prospective study was approved by all relevant institutional review boards. All patients gave their signed informed consent. In this study, 20 healthy volunteers (mean age, 62 years; age range, 37-78 years; mean body mass index, 29.26; body mass index range, 21.63-42.17; 16 men, 4 women) underwent a supine low-dose CT scan and an upright CBCT scan of the upper airway. The (local) average (Savg) and minimal (Smin) cross-sectional area, the position of the latter, the concavity, and the airway resistance were examined to determine if they changed from the upright to the supine position. If changes were found, baseline parameters were sought that were indicators for these differences. Results: There were five dropouts due to movement artifacts in the CBCT scans. Savg and Smin were 9.76% and 26.90% larger, respectively, in the CBCT scan than in the CT scan, whereas the resistance decreased by 26.15% in the upright position. The Savg of the region between the hard palate and the bottom of the uvula increased the most (49.85%). In people with a high body mass index, this value changed the least. The airway resistance in men decreased more than in women. Conclusions: This study demonstrated that there are differences in upper airway morphology and functionality between the supine and upright positions and that there are baseline indicators for these differences.
    Journal of Aerosol Medicine and Pulmonary Drug Delivery 03/2013; · 2.89 Impact Factor

Publication Stats

2k Citations
718.21 Total Impact Points


  • 1983–2013
    • University of Antwerp
      • • Departement Fysica
      • • Faculty of Medicine
      Antwerpen, Flanders, Belgium
  • 2011
    • University of Gothenburg
      Goeteborg, Västra Götaland, Sweden
    • Artesis Plantijn Hogeschool Antwerpen
      Bruxelles, Brussels Capital Region, Belgium
  • 2010
    • University of California, San Francisco
      • Department of Otolaryngology - Head and Neck Surgery
      San Francisco, California, United States
  • 2005
    • Universitair Ziekenhuis Leuven
      Louvain, Flanders, Belgium
  • 2000–2002
    • Maastricht University
      • Pulmonologie
      Maastricht, Provincie Limburg, Netherlands
  • 1995–1996
    • Akademiska Sjukhuset
      Uppsala, Uppsala, Sweden
  • 1992
    • Universitair Ziekenhuis Ghent
      Gand, Flanders, Belgium