Basic concepts for tidal volume and leakage estimation in non-invasive ventilation

Non-invasive ventilation (NIV) aims to maintain sufficient alveolar ventilation, improve pulmonary gas exchange, assist respiratory muscles, and decrease work of breathing. Monitoring variables such as leaks, tidal volume, and minute ventilation during therapy is crucial to assess the effectiveness of NIV. However, most of the time, leaks and tidal volume are not measured but estimated by NIV devices. Moreover, there are limited data for the accuracy and reliability of these estimations. Herein, we address some technical considerations for tidal volume and leakage estimation during NIV and its impact in clinical practice

Effect of a rehabilitation-based chronic disease management program targeting severe COPD exacerbations on readmission patterns

Pulmonary rehabilitation (PR) is recommended after a severe COPD exacerbation, but its short- and long-term effects on health care utilization have not been fully established. The aims of this study were to evaluate patient compliance with a chronic disease management (CDM) program incorporating home-based exercise training as the main component after a severe COPD exacerbation and to determine its effects on health care utilization in the following year. COPD patients with a severe exacerbation were included in a case-cohort study at admission. An intervention group participated in a nurse-supervised CDM program during the 2 months after discharge, comprising of home-based PR with exercise components directly supervised by a physiotherapist, while the remaining patients followed usual care. Nineteen of the twenty-one participants (90.5%) were compliant with the CDM program and were compared with 29 usual-care patients. Compliance with the program was associated with statistically significant reductions in admissions due to respiratory disease in the following year (median [interquartile range]: 0 [0-1] vs 1 [0-2.5]; P =0.022) and in days of admission (0 [0-7] vs 7 [0-12]; P =0.034), and multiple linear regression analysis confirmed the protective effect of the CDM program (β coefficient −0.785, P =0.014, and R 2 =0.219). A CDM program incorporating exercise training for COPD patients without limiting comorbidities after a severe exacerbation achieves high compliance and reduces admissions in the year following after the intervention

Asincronías paciente-ventilador en ventilación mecánica no invasiva. Del laboratorio a la práctica clínica

La prevalença i tipologia de les asincronies pacient-ventilador es coneix en trets molt generals a la pràctica clínica de la ventilació domiciliària no invasiva (VMNID), però no s'ha descrit detalladament a la literatura. Aquesta manca d'informació fa referència també a diferents fenòmens intrínsecs i extrínsecs que poden intervenir durant el tractament. L'objectiu del projecte és determinar la presència i el tipus d'asincronies en diferents condicions de mecànica pulmonar i demanda ventilatòria i en diferents models de ventiladors en un entorn de banc de proves i, posteriorment, verificació dels resultats en l'entorn clínic. Es van dissenyar tres estudis de banc de proves que simulaven diferents tipus de pacient en diferents condicions de fuga no intencional, introducció de gasos al circuit i variacions en la demanda inspiratòria. Es va utilitzar un simulador actiu connectat a un polígraf de senyals i a un pneumotacògraf extern. Es van analitzar els registres utilitzant un programari integrat en el polígraf. De la mateixa manera, es va comprovar l'aparició d'asincronies en condicions similars en pacients reals per avaluar la coincidència dels resultats. Els resultats obtinguts van mostrar diferències significatives en el comportament de la ventiladors per a VMNIDs en funció del disseny del trigger i la pressurització, tant a nivell de banc de proves com en entorns clínics. Aquestes diferències van influir en la presència i tipus d'asincronies en pacients sota VMNID. Concretament, després de introducció d'un gas extern al circuit, els ventiladors provats van mostrar diferents respostes i diferents graus de correcció. Aquests comportaments van ser diferents en funció de la quantitat de gas, el nivell d'activació i el tipus de font externa de gas utilitzat. També hi va haver diferències en l'entorn de laboratori en la resposta de diferents models de ventiladors davant d'un model de fuita no intencional. Finalment també van demostrar diferències significatives a nivell de capacitat de pressurització en una sèrie de ventiladors en un entorn de banc de proves davant esforços progressivament creixents. Un cop classificats els ventiladors en funció dels resultats del banc de proves, els models amb un millor comportament al banc de proves va provocar una major descàrrega muscular a igualtat de pressió suport en una cohort de pacients amb MPOC. La conclusió del projecte és que la combinació dels factors estudiats aïllats o combinats, tant intrínsecs com extrínsecs al pacient amb VMNID, van influir en l'aparició d'asincronies pacient-ventilador. El coneixement de la fisiopatologia pulmonar a nivell del pacient i el funcionament tècnic dels dispositius utilitzats en la pràctica clínica és essencial per a l'eficàcia del VMNID.La prevalencia y tipología de las asincronías paciente-ventilador es conocida en rasgos muy generales en la práctica clínica de la ventilación no invasiva domiciliaria (VMNID), pero no ha sido detalladamente descrita o estudiada en la literatura. Esta carencia de información se encuentra frente a diferentes fenómenos intrínsecos y extrínsecos al paciente que pueden intervenir en su aparición durante el tratamiento. El objetivo del proyecto fue determinar la presencia y el tipo de asincronías bajo diferentes condiciones de mecánica pulmonar y demanda ventilatoria y frente a diferentes modelos de ventiladores comerciales en un entorno de banco de pruebas y verificar los resultados en el entorno clínico real. Se diseñaron tres estudios en banco de pruebas que simularon diferentes tipos de paciente bajo diferentes condiciones de fuga no intencional, introducción de gas terapéutico o variaciones en la demanda inspiratoria. Para ello se utilizó un simulador respiratorio conectado a un polígrafo de señales y un neumotacógrafo externo. Se analizaron los registros mediante un software incorporado al polígrafo. De igual manera, se comprobó la aparición de asincronías bajo las mismas condiciones en paciente real para comprobar la coincidencia o no de los resultados. Los resultados obtenidos mostraron diferencias significativas en el comportamiento de los ventiladores para VMNID en función del diseño del trigger y de la presurización, tanto a nivel de banco de pruebas como en entorno clínico. Estas diferencias influyeron en la presencia y el tipo de asincronías en pacientes bajo VMNID. De forma específica, tras introducción de un gas externo en el circuito, los ventiladores probados mostraron diferentes respuestas y distintos grados de corrección. Estos comportamientos fueron diferentes según la cantidad de gas, el nivel de activación y el tipo de fuente de gas externa empleada. También existieron diferencias en entorno de laboratorio en la respuesta de diferentes modelos de ventilador ante un modelo de fuga no intencional. Finalmente, se demostraron también diferencias significativas a nivel de capacidad de presurización en una serie de ventiladores en entorno de banco de pruebas ante esfuerzos crecientes. Una vez categorizados en función de los resultados en banco de pruebas, los ventiladores con mejor comportamiento en banco causaron mayor descarga muscular a igualdad de presión soporte en una cohorte de pacientes con EPOC. La conclusión del proyecto es que la combinación de los factores estudiados de manera aislada o combinada, tanto intrínsecos, como extrínsecos al paciente con VMNID, influyeron en la aparición de asincronías paciente-ventilador. El conocimiento de la fisiopatología pulmonar del paciente y del funcionamiento técnico de los dispositivos utilizados en la práctica clínica es esencial para la efectividad de la VMNID.The prevalence and types of patient-ventilator asynchronies is roughly known in the clinical practice of non-invasive home ventilation, but it has not been described or studied in-depth in the literature. This lack of information is faced with different phenomena intrinsic and extrinsic to the patient that may intervene in its appearance during treatment. The objective of the project was to determine the presence and type of asynchronies under different conditions of lung mechanics and ventilatory demand and against different models of commercial ventilators in a test bench environment. After that, the results were compared with the real clinical environment. Three test bench studies that simulated different types of patients under different conditions of unintentional leakage, introduction of therapeutic gas, or variations in inspiratory demand were designed. For this purpose, a respiratory simulator connected to a signal polygraph and an external pneumotachograph were used. The records were analysed using software incorporated to the polygraph. In the same way, the appearance of asynchronies was verified under the same conditions in clinical environment (real patients) to verify the coincidence or not of the results. The results obtained showed significant differences in the behaviour of the ventilators for depending on the design of the trigger and the pressurization, both at the bench model and in the clinical environment. Specifically, after introducing an external gas into the circuit, the tested ventilators showed different responses and different degrees of correction. These behaviours were different depending on the amount of gas, the level of activation and the type of external gas source used. There were also differences in the laboratory environment in the response of different ventilator models to an unintentional leak model. Finally, significant differences related to the pressurization capacity in a group of ventilators in a bench environment in the face of increasing efforts were also demonstrated. Once categorized based on test bench results, ventilators with better performance in the bench model presented greater muscle unloading at equal pressure support in a cohort of COPD patients. The conclusion of the project is that the combination of factors studied in isolation or in combination, both intrinsic and extrinsic to the patient with non-invasive ventilation, influenced the appearance of patient-ventilator asynchronies. Knowledge of the patient's pulmonary pathophysiology and the technical performance of the devices used in clinical practice is essential for the effectiveness of the therapy

Effect of a rehabilitation-based chronic disease management program targeting severe COPD exacerbations on readmission patterns

Pulmonary rehabilitation (PR) is recommended after a severe COPD exacerbation, but its short- and long-term effects on health care utilization have not been fully established. The aims of this study were to evaluate patient compliance with a chronic disease management (CDM) program incorporating home-based exercise training as the main component after a severe COPD exacerbation and to determine its effects on health care utilization in the following year. COPD patients with a severe exacerbation were included in a case-cohort study at admission. An intervention group participated in a nurse-supervised CDM program during the 2 months after discharge, comprising of home-based PR with exercise components directly supervised by a physiotherapist, while the remaining patients followed usual care. Nineteen of the twenty-one participants (90.5%) were compliant with the CDM program and were compared with 29 usual-care patients. Compliance with the program was associated with statistically significant reductions in admissions due to respiratory disease in the following year (median [interquartile range]: 0 [0-1] vs 1 [0-2.5]; P =0.022) and in days of admission (0 [0-7] vs 7 [0-12]; P =0.034), and multiple linear regression analysis confirmed the protective effect of the CDM program (β coefficient −0.785, P =0.014, and R 2 =0.219). A CDM program incorporating exercise training for COPD patients without limiting comorbidities after a severe exacerbation achieves high compliance and reduces admissions in the year following after the intervention

Does the Efficacy of High Intensity Ventilation in Stable COPD Depend on the Ventilator Model? A Bench-to-Bedside Study

The European Task Force for chronic non-invasive ventilation in stable COPD recommends the use of high pressure-support (PS) level to maximize the decrease in PaCO2. It is possible that the ventilator model can influence the need for higher or lower pressure levels. To determine the differences between ventilators in a bench model with an increased inspiratory demand; and to compare the degree of muscular unloading measured by parasternal electromyogram (EMGpara) provided by the different ventilators in real patients with stable COPD. Bench: four levels of increasing progressive effort were programmed. The response of nine ventilators to four levels of PS and EPAP of 5 cm H2O was studied. The pressure-time product was determined at 300 and 500 msec (PTP 300/500). The ventilators were divided into two groups, based on the result of the bench test. Severe COPD patients with non-invasive ventilation (NIV) were studied, randomly comparing the performance of one ventilator from each group. Muscle unloading was measured by the decrease in EMGpara from its baseline value. There were significant differences in PTP 300 and PTP 500 in the bench study. Based on these results, home ventilators were classified into two groups; group 1 included four models with higher PTP 300. Ten COPD patients were recruited for the clinical study. Group 1 ventilators showed greater muscle unloading at the same PS than group 2. The scale of pressure support in NIV for high intensity ventilation may be influenced by the ventilator model. NCT0337317

Integrated 3D printing solution to mitigate shortages of airway consumables and personal protective equipment during the COVID-19 pandemic

Background: To cope with shortages of equipment during the COVID-19 pandemic, we established a nonprofit end-to-end system to identify, validate, regulate, manufacture, and distribute 3D-printed medical equipment. Here we describe the local and global impact of this system. Methods: Together with critical care experts, we identified potentially lacking medical equipment and proposed solutions based on 3D printing. Validation was based on the ISO 13485 quality standard for the manufacturing of customized medical devices. We posted the design files for each device on our website together with their technical and printing specifications and created a supply chain so that hospitals from our region could request them. We analyzed the number/type of items, petitioners, manufacturers, and catalogue views. Results: Among 33 devices analyzed, 26 (78·8%) were validated. Of these, 23 (88·5%) were airway consumables and 3 (11·5%) were personal protective equipment. Orders came from 19 (76%) hospitals and 6 (24%) other healthcare institutions. Peak production was reached 10 days after the catalogue was published. A total of 22,135 items were manufactured by 59 companies in 18 sectors; 19,212 items were distributed to requesting sites during the busiest days of the pandemic. Our online catalogue was also viewed by 27,861 individuals from 113 countries. Conclusions: 3D printing helped mitigate shortages of medical devices due to problems in the global supply chain

Relationship between the respiratory microbiome and the severity of airflow limitation, history of exacerbations and circulating eosinophils in COPD patients

Background: The respiratory microbiome is altered in COPD patients but its relationship with core components of the disease, such as the severity of airflow limitation, the frequency of exacerbations or the circulating levels of eosinophils, is unclear. Methods: Cross-sectional study comprising 72 clinically stable COPD patients (mean age 68 [SD 7.9] years; FEV1 48.7 [SD 20.1]% of reference) who provided spontaneous sputum samples for 16S rRNA gene amplification and sequencing. The microbiome composition was analysed with QIIME. Results: We observed that: (1) more severe airflow limitation was associated with reduced relative abundance (RA) of Treponema and an increase in Pseudomonas; (2) patients with ≥2 exacerbations the previous year showed a significantly different bacterial community with respect to non-exacerbators (p = 0.014), with changes in 13 genera, including an increase of Pseudomonas, and finally, (3) peripheral eosinophils levels ≥2% were associated with more diverse microbiome [Chao1 224.51 (74.88) vs 277.39 (78.92) p = 0.006; Shannon 3.94 (1.05) vs 4.54 (1.06) p = 0.020], and a significant increase in the RAs of 20 genera. Conclusion: The respiratory microbiome in clinically stable COPD patients varies significantly according to the severity of airflow limitation, previous history of exacerbations and circulating eosinophils levels.This study was funded by FIS PI15/00167 and PI15/02042 from Instituto de Salud Carlos III (ISCIII), SAF 2014–54371 (FEDER) from Ministerio de Economía y Competitividad, Sociedad Española de Neumología y Cirugía Torácica (SEPAR), Laboratorios Menarini S. A, Fundació Pla Armengol and Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES). CIBERES is an initiative of the ISCIII

Relationship between the respiratory microbiome and the severity of airflow limitation, history of exacerbations and circulating eosinophils in COPD patients

Background: The respiratory microbiome is altered in COPD patients but its relationship with core components of the disease, such as the severity of airflow limitation, the frequency of exacerbations or the circulating levels of eosinophils, is unclear. Methods: Cross-sectional study comprising 72 clinically stable COPD patients (mean age 68 [SD 7.9] years; FEV1 48.7 [SD 20.1]% of reference) who provided spontaneous sputum samples for 16S rRNA gene amplification and sequencing. The microbiome composition was analysed with QIIME. Results: We observed that: (1) more severe airflow limitation was associated with reduced relative abundance (RA) of Treponema and an increase in Pseudomonas; (2) patients with ≥2 exacerbations the previous year showed a significantly different bacterial community with respect to non-exacerbators (p = 0.014), with changes in 13 genera, including an increase of Pseudomonas, and finally, (3) peripheral eosinophils levels ≥2% were associated with more diverse microbiome [Chao1 224.51 (74.88) vs 277.39 (78.92) p = 0.006; Shannon 3.94 (1.05) vs 4.54 (1.06) p = 0.020], and a significant increase in the RAs of 20 genera. Conclusion: The respiratory microbiome in clinically stable COPD patients varies significantly according to the severity of airflow limitation, previous history of exacerbations and circulating eosinophils levels.This study was funded by FIS PI15/00167 and PI15/02042 from Instituto de Salud Carlos III (ISCIII), SAF 2014–54371 (FEDER) from Ministerio de Economía y Competitividad, Sociedad Española de Neumología y Cirugía Torácica (SEPAR), Laboratorios Menarini S. A, Fundació Pla Armengol and Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES). CIBERES is an initiative of the ISCIII