Respiratory muscle activity and patient–ventilator asynchrony during different settings of noninvasive ventilation in stable hypercapnic COPD: does high inspiratory pressure lead to respiratory muscle unloading?

Marieke L Duiverman,1 Anouk S Huberts,2 Leo A van Eykern,3 Gerrie Bladder,1 Peter J Wijkstra1 1Department of Pulmonary Diseases and Home Mechanical Ventilation, University Medical Centre Groningen, 2Faculty of Medical Sciences, University of Groningen, 3Inbiolab B.V., Groningen, the Netherlands Introduction: High-intensity noninvasive ventilation (NIV) has been shown to improve outcomes in stable chronic obstructive pulmonary disease patients. However, there is insufficient knowledge about whether with this more controlled ventilatory mode optimal respiratory muscle unloading is provided without an increase in patient–ventilator asynchrony (PVA). Patients and methods: Ten chronic obstructive pulmonary disease patients on home mechanical ventilation were included. Four different ventilatory settings were investigated in each patient in random order, each for 15 min, varying the inspiratory positive airway pressure and backup breathing frequency. With surface electromyography (EMG), activities of the intercostal muscles, diaphragm, and scalene muscles were determined. Furthermore, pressure tracings were derived simultaneously in order to assess PVA. Results: Compared to spontaneous breathing, the most pronounced decrease in EMG activity was achieved with the high-pressure settings. Adding a high breathing frequency did reduce EMG activity per breath, while the decrease in EMG activity over 1 min was comparable with the high-pressure, low-frequency setting. With high backup breathing frequencies less breaths were pressure supported (25% vs 97%). PVAs occurred more frequently with the low-frequency settings (P=0.017). Conclusion: High-intensity NIV might provide optimal unloading of respiratory muscles, without undue increases in PVA. Keywords: electromyography, high-intensity NIV, chronic obstructive pulmonary disease, ineffective effort

Reproducibility and responsiveness of a noninvasive EMG technique of the respiratory muscles in COPD patients and in healthy subjects

In the present study, we assessed the reproducibility and responsiveness of transcutaneous electromyography (EMG) of the respiratory muscles in patients with chronic obstructive pulmonary disease ( COPD) and healthy subjects during breathing against an inspiratory load. In seven healthy subjects and seven COPD patients, EMG signals of the frontal and dorsal diaphragm, intercostal muscles, abdominal muscles, and scalene muscles were derived on 2 different days, both during breathing at rest and during breathing through an inspiratory threshold device of 7, 14, and 21 cmH(2)O. For analysis, we used the logarithm of the ratio of the inspiratory activity during the subsequent loads and the activity at baseline [ log EMG activity ratio (EMGAR)]. Reproducibility of the EMG was assessed by comparing the log EMGAR values measured at test days 1 and 2 in both groups. Responsiveness ( sensitivity to change) of the EMG was assessed by comparing the log EMGAR values of the COPD patients to those of the healthy subjects at each load. During days 1 and 2, log EMGAR values of the diaphragm and the intercostal muscles correlated significantly. For the scalene muscles, significant correlations were found for the COPD patients. Although inspiratory muscle activity increased significantly during the subsequent loads in all participants, the COPD patients displayed a significantly greater increase in intercostal and left scalene muscle activity compared with the healthy subjects. In conclusion, the present study showed that the EMG technique is a reproducible and sensitive technique to assess breathing patterns in COPD patients and healthy subjects

Home noninvasive ventilatory support for patients with chronic obstructive pulmonary disease: patient selection and perspectives

Jan Hendrik Storre,1,2 Jens Callegari,3 Friederike Sophie Magnet,3 Sarah Bettina Schwarz,3 Marieke Leontine Duiverman,4,5 Peter Jan Wijkstra,4,5 Wolfram Windisch3 1Department of Intensive Care, Sleep Medicine and Mechanical Ventilation, Asklepios Fachkliniken Munich-Gauting, Gauting, Germany; 2Department of Pneumology, University Medical Hospital, Freiburg, Germany; 3Department of Pneumology, Cologne Merheim Hospital, Kliniken der Stadt Köln gGmbH Witten/Herdecke University, Faculty of Health/School of Medicine, Cologne, Germany; 4Department of Pulmonary Diseases, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; 5Groningen Research Institute of Asthma and COPD (GRIAC), University of Groningen, Groningen, the Netherlands Abstract: Long-term or home mechanical noninvasive ventilation (Home-NIV) has become a well-established form of therapy over the last few decades for chronic hypercapnic COPD patients in European countries. However, meta-analyses and clinical guidelines do not recommend Home-NIV for COPD patients on a routine basis. In particular, there is ongoing debate about Home-NIV in chronic hypercapnic COPD regarding the overall effects, the most favorable treatment strategy, the selection of eligible patients, and the time point at which it is prescribed. The current review focuses on specific aspects of patient selection and discusses the various scientific as well as clinical-guided perspectives on Home-NIV in patients suffering from chronic hypercapnic COPD. In addition, special attention will be given to the topic of ventilator settings and interfaces. Keywords: exacerbation, pulmonary emphysema, hypercapnia, mechanical ventilation, respiratory insufficienc

Improvement in hypercapnia does not predict survival in COPD patients on chronic noninvasive ventilation

Tim Raveling,1 Gerrie Bladder,2 Judith M Vonk,3,4 Jellie A Nieuwenhuis,2,3 Fransien M Verdonk-Struik,5 Peter J Wijkstra,2,3 Marieke L Duiverman2,3 1Faculty of Medical Sciences, University of Groningen, Groningen, the Netherlands; 2Department of Pulmonary Diseases and Home Mechanical Ventilation, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; 3Groningen Research Institute of Asthma and COPD (GRIAC), University of Groningen, Groningen, the Netherlands; 4Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; 5Primary Care Group Gelders Rivierenland, Ochten, the Netherlands Purpose: It has recently been shown that chronic noninvasive ventilation (NIV) improves a number of outcomes including survival, in patients with stable hypercapnic COPD. However, the mechanisms responsible for these improved outcomes are still unknown. The aim of the present study was to identify parameters associated with: 1) an improved arterial partial pressure of carbon dioxide (PaCO2) and 2) survival, in a cohort of hypercapnic COPD patients treated with chronic NIV. Patients and methods: Data from 240 COPD patients treated with chronic NIV were analyzed. Predictors for the change in PaCO2 and survival were investigated using multivariate linear and Cox regression models, respectively. Results: A higher level of bicarbonate before NIV initiation, the use of higher inspiratory ventilator pressures, the presence of anxiety symptoms, and NIV initiated following an exacerbation compared to NIV initiated in stable disease were associated with a larger reduction in PaCO2. A higher body mass index, a higher FEV1, a lower bicarbonate before NIV initiation, and younger age and NIV initiation in stable condition were independently associated with better survival. The change in PaCO2 was not associated with survival, neither in a subgroup of patients with a PaCO2 >7.0 kPa before the initiation of NIV. Conclusion: Patients with anxiety symptoms and a high bicarbonate level at NIV initiation are potentially good responders in terms of an improvement in hypercapnia. Also, higher inspiratory ventilator pressures are associated with a larger reduction in PaCO2. However, the improvement in hypercapnia does not seem to be associated with an improved survival and emphasizes the need to look beyond PaCO2 when considering NIV initiation. Keywords: carbon dioxide, home mechanical ventilation, exacerbation, bicarbonate, chronic obstructive pulmonary disease, respiratory insufficienc

No effects of probiotics on atopic dermatitis in infancy:a randomized placebo-controlled trial

Studies have been performed suggesting that administration of probiotics may have therapeutic and/or preventive benefits in the development of sensitization and atopic disease, particularly in infants with atopic dermatitis (AD). The purpose of this study was to evaluate the clinical and immunological effects of supplementation of a hydrolysed formula with two probiotic strains of bacteria on symptoms of AD in infancy. We conducted a randomized, double-blind, placebo-controlled study. After 4-6 weeks of baseline and double-blind, placebo-controlled challenges for diagnosis of cow's milk allergy (CMA), infants less than 5 months old with AD received a hydrolysed whey-based formula as placebo (n=17), or supplemented with either Lactobacillus rhamnosus (n=17) or Lactobacillus GG (n=16) for 3 months. Before, during and after intervention, the clinical severity of AD was evaluated using SCORing index Atopic Dermatitis (SCORAD). Allergic sensitization was evaluated by measurement of total IgE and a panel of food-specific IgEs as well as skin prick testing for cow's milk. Inflammatory parameters were blood eosinophils, eosinophil protein X in urine, fecal alpha-1-antitrypsin and production of IL-4, IL-5 and IFN-gamma by peripheral blood mononuclear cells after polyclonal stimulation. No statistically significant effects of probiotic supplementation on SCORAD, sensitization, inflammatory parameters or cytokine production between groups were found. Only four infants were diagnosed with CMA. We found no clinical or immunological effect of the probiotic bacteria used in infants with AD. Our results indicate that oral supplementation with these probiotic bacterial strains will not have a significant impact on the symptoms of infantile AD