Chris van der Grinten

Respiratory impedance in healthy subjects: baseline values and bronchodilator response

Because of the minimal demand for cooperation by the subject, the forced oscillation technique is increasingly employed in routine lung function testing. However, comprehensive and device-independent values of respiratory impedance at baseline and after bronchodilation have not been established for healthy adults. The aim of this multicentre study was to collect impedance data from 4 to 26 Hz in healthy Caucasian subjects between 18 and 80 years of age. Five different devices were employed to assess baseline values and the bronchodilator response. Altogether, 368 subjects were examined. Despite adjustment for anthropometry, the impedance spectra differed in frequency dependence between the centres, and hence could not be pooled. However, resistance at all frequencies except 20 and 25 Hz, and the low-frequency (≤14 Hz) values of reactance did not exhibit a centre dependence. The regression equations for resistance reflected a greater height dependence in males and a greater weight dependence in both males and females than those published previously. Bronchodilation resulted in a statistically significant decrease (11%) in resistance and a 95th percentile equal to a 32% decrease in resistance at low frequency. We conclude that rigorous calibration procedures should be developed to ensure data compatibility. Furthermore, new reference equations based on different setups are recommended to replace those established with a single device. New prediction equations for respiratory impedance in adults have been developed based on multiple devices http://ow.ly/p9t4e

Risk factors for lung disease progression in children with cystic fibrosis

To identify potential risk factors for lung disease progression in children with cystic fibrosis (CF), we studied the longitudinal data of all children with CF (aged ≥5 years) registered in the Dutch CF Registry (2009–2014). Lung disease progression was expressed as a decline in lung function (forced expiratory volume in 1 s (FEV1) % pred) and pulmonary exacerbation rate. Potential risk factors at baseline included sex, age, best FEV1 % pred, best forced vital capacity % pred, genotype, body mass index z-score, pancreatic insufficiency, medication use (proton pump inhibitors (PPIs), prophylactic antibiotics and inhaled corticosteroids), CF-related diabetes, allergic bronchopulmonary aspergillosis and colonisation with Pseudomonas aeruginosa. The data of 545 children were analysed. PPI use was associated with both annual decline of FEV1 % pred (p=0.017) and future pulmonary exacerbation rate (p=0.006). Moreover, lower FEV1 % pred at baseline (p=0.007), prophylactic inhaled antibiotic use (p=0.006) and pulmonary exacerbations in the baseline year (p=0.002) were related to pulmonary exacerbations in subsequent years. In a cohort of Dutch children with CF followed for 5 years, we were able to identify several risk factors for future exacerbations. In particular, the association between PPI use and lung disease progression definitely requires further investigation. The association between the use of proton pump inhibitors and lung disease progression in children with cystic fibrosis requires further investigation http://ow.ly/hiTc30jACAU

Case Report: Bilateral diaphragmatic dysfunction due to Borrelia Burgdorferi

Summary: In this case report we describe a rare case of bilateral diaphragmatic dysfunction due to Lyme disease. Case report: A 62-years-old male presented to the hospital because of flu-like symptoms. During initial evaluation a bilateral diaphragmatic weakness with orthopnea and nocturnal hypoventilation was observed, without a known aetiology. Bilateral diaphragmatic paralysis was confirmed by fluoroscopy with a positive sniff test. The patient was referred to our centre for chronic non-invasive nocturnal ventilation (cNPPV). Subsequent investigations revealed evidence of anti- Borrelia seroactivity in EIA-IgG and IgG-blot, suggesting a recent infection with Lyme disease, and resulted in a 4-week treatment with oral doxycycline. The symptoms of nocturnal hypoventilation were successfully improved with cNPPV. However, our patient still shows impaired diaphragmatic function but he is no longer fully dependent on nocturnal ventilatory support. Conclusion: Lyme disease should be considered in the differential diagnosis of diaphragmatic dysfunction. It is a tick-borne illness caused by one of the three pathogenic species of the spirochete Borrelia burgdorferi, present in Europe. A delay in recognizing the symptoms can negatively affect the success of treatment. Non-invasive mechanical ventilation (NIV) is considered a treatment option for patients with diaphragmatic paralysis.