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

PURPOSE: 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. RESEARCH QUESTION: 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. PATIENTS AND METHODS: 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). CLINICAL STUDY: 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. RESULTS: 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. CONCLUSION: The scale of pressure support in NIV for high intensity ventilation may be influenced by the ventilator model. CLINICAL TRIALSGOV: NCT03373175.

A bench-to-bedside study about trigger asynchronies induced by the introduction of external gas into the non-invasive mechanical ventilation circuit.

Treatments that require the introduction of external gas into the non-invasive ventilation (NIV) circuit, such as aerosol and oxygen therapy, may influence the performance of the ventilator trigger system. The aim of the study was to determine the presence and type of asynchronies induced by external gas in the NIV circuit in a bench model and in a group of patients undergoing chronic NIV. Bench study: Four ventilators (one with two different trigger design types) and three gas sources (continuous flow at 4 and 9 l/min and pulsatile flow at 9 l/min) were selected in an active simulator model. The sensitivity of the trigger, the gas introduction position, the ventilatory pattern and the level of effort were also modified. The same ventilators and gas conditions were used in patients undergoing chronic NIV. Bench: the introduction of external gas caused asynchronies in 35.9% of cases (autotriggering 73%, ineffective effort 27%). Significant differences (p < 0.01) were detected according to the ventilator model and the gas source. In seven patients, the introduction of external gas induced asynchrony in 20.4% of situations (77% autotriggering). As in the bench study, there were differences in the occurrence of asynchronies depending on the ventilator model and gas source used. The introduction of external gas produces alterations in the ventilator trigger. These alterations are variable, and depend on the ventilator design and gas source. This phenomenon makes it advisable to monitor the patient at the start of treatment.

Assessment of methylation status of locoregional lymph nodes in lung cancer using EBUS-NA.

Hypermethylation of the promoter region of tumor suppressor genes is associated with carcinogenesis in lung cancer (LC). Endobronchial ultrasound with needle aspiration (EBUS-NA) is a semi-invasive method for obtaining cell blocks from lymph nodes, which can be used for epigenetic analyses. To establish the relationship between methylation status of p16, DAPK, RASSF1a, APC and CDH13 genes in lymph nodes sampled by EBUS-NA, tumor staging and prognosis. Methylation status of DAPK, p16, RASSF1a, APC and CDH13 genes was assessed in EBUS-NA cell blocks from LC patients and related to stage and survival. Eighty-five consecutive patients [mean age 67 (SD 8)] were included. Methylation of ≥1 gene was found in 43 malignant nodes (67 %). A higher prevalence of RASSF1a methylation was observed in small cell lung cancer patients [9/10 (90 %) vs. 15/53 (28 %); p < 0.001 χ(2) test]. Methylation of APC and/or p16 was related to advanced staging in non-small cell lung cancer (NSCLC) [15/29 (52 %) vs. 6/24 (25 %), p = 0.048, χ(2) test]. Patients with NSCLC showing methylation of APC and/or p16 had also lower 6-month survival (p = 0.019, log rank test), which persisted after adjustment for age and subtyping (HR = 6, 95 % CI [1.8-19.5], p = 0.003, Cox regression). Epigenetic analyses are feasible in EBUS-NA cell blocks and may identify methylation patterns associated with worse prognosis. Methylation of p16 and APC genes in NSCLC patients was associated with advanced staging and lower 6-month survival.

Influence of dynamic leaks in volume-targeted pressure support noninvasive ventilation: a bench study.

INTRODUCTION: The effect of leaks on volume-targeted pressure support noninvasive ventilation mode has only been tested with continuous simulated leaks. The objective of the study was to assess the influence of random leaks occurring either during inspiration or expiration. METHODS: Analysis of the volume-targeted pressure support mode in 6 commercial ventilators with single-limb circuits and intentional leak in a bench study (restrictive model). Unintentional leaks were introduced through a mechanical system during inspiration (threshold valve with 2 levels of leaks) or during expiration (active valve). Results of delivered tidal volume (VT) and pressure support were externally recorded. A pre-set VT of 550 mL was programmed, with a wide range of pressure support values. RESULTS: All the ventilators showed a deviation of delivered versus programmed VT below 10% in the period without unintentional leaks. In the model with unintentional inspiratory leaks, a progressive drop in delivered VT and pressure support was observed for all ventilators. The reduction in the delivered VT for the highest inspiratory leak ranged between 21 and 40%, corresponding to a decrease in pressure support between 3.09 and 10.15 cm H2O after 5 min. Conversely, in the expiratory model, increases in delivered VT and pressure support were observed, ranging between 16 and 33% and between 2.7 and 6.5 cm H2O, respectively. CONCLUSIONS: The introduction of random leaks influences the performance of commercial ventilators with single-limb circuits and intentional leak. The decrease in delivered VT with inspiratory leaks reaches a magnitude that may have clinically important impacts.