Long-Term Effect of Noninvasive Ventilation on Diaphragm in Chronic Respiratory Failure.

PURPOSE: Home non-invasive ventilation (NIV) is recommended in patients with COPD and hypercapnic chronic respiratory failure (HCRF). The mechanism by it can improve alveolar ventilation during spontaneous breathing is not yet completely explained. Our aim is to evaluate the impact of on diaphragm muscle function in a series of patients with HCRF. PATIENTS AND METHODS: Observational, longitudinal, prospective study of a series of patients with very severe chronic obstruction to airflow treated with home high imntensity NIV (HINIV). Patients underwent a baseline and after 12 months assessment including adherence to treatment, quality of life, respiratory function tests and diaphragmatic ultrasound. SPSS v.26 software was used for statistical analysis. RESULTS: We studied 30 patients, 63% male, the mean age was 60.8 (±6.4) years old. Patients had a severe obstructive ventilatory pattern [FEV1 21.8 (±6.1)%] and hypercapnia [pCO2 56.4 (±7.2) mmHg]. After 12 months of HINIV, we observed significant increases in FVC of 9.2% (p = 0.002), FEV1 of 3.5% (p = 0.04), MIP of 9.4% (p = 0.006), and 6-minute-walking test (6MWT) of 31.9 m (p = 0.001), as well as decreases in paCO2 of 12.5 mmHg (p = 0.001), HCO3 of 4.7 mmol/L (p = 0.001) and BODE index from 7 to 6. Diaphragmatic ultrasound demonstrated an increase in the thickening fraction of 14% (p = 0.002). Respiratory symptoms (p = 0.04), physical function (p = 0.03), and sleep (p = 0.04) also improved. CONCLUSION: In patients with HCRF due to very severe chronic obstruction to airflow, long-term HINIV can improve respiratory performance by improving the function of the diaphragmatic musculature. Larger multicenter clinical trials are needed to confirm the results suggested in this study.

The addition of a humidifier device to a circuit and its impact on home ventilator performance: a bench study.

INTRODUCTION AND OBJECTIVES: Humidification and non-invasive ventilation are frequently used together, despite the lack of precise recommendations regarding this practice. We aimed to analyse the impact of active external and built-in humidifiers on the performance of home ventilators, focusing on their pressurization efficacy and their behaviour under different inspiratory efforts. METHODS: We designed a bench study of a lung simulator programmed to emulate mechanical conditions similar to those experienced by real respiratory patients and to simulate three different levels of inspiratory effort: five different commonly used home NIV devices and active humidifiers attached to the latter (internal or "built-in") or to the circuit (external). To test ventilator pressurization under different humidification and effort settings, pressure-time products in the first 300ms and 500ms of the respiratory cycle were calculated in the 45 situations simulated. Inferential statistical analysis was performed. RESULTS: A significant reduction of PTP 300 and PTP 500 was observed with the external humidifier in three of the devices. The same pattern was noted for another device with an internal humidifier, and only one device showed no significant changes. This impact on pressurization was commonly higher under high inspiratory effort. CONCLUSIONS: These results indicate the need to monitor pressure changes in the use of external humidification devices in some home NIV ventilators.