Thermo-humidified nasal high flow (NHF) oxygen therapy is increasingly used in the management of respiratory failure. This therapy has recently gained attention as an alternative non-invasive respiratory support in several clinical scenarios, including acute and chronic settings. NHF enhances the patient's comfort and tolerance when compared with standard oxygen by supplying a heated and humidified mixture of air and oxygen at flows up to 60L/min. It can be delivered through different devices. Although few studies have compared the clinical effects of different NHF systems, the purpose of this paper is to describe the major benefits of NHF and to provide a quick guide on how to implement this therapy in daily practice. We have also included a brief description of the most frequently used NHF systems.

The objective of this article is to review the most recent literature regarding the management of acute hypercapnic respiratory failure (AHRF). In the field of AHRF management, noninvasive ventilation (NIV) has become the standard method of providing primary mechanical ventilator support. Recently, extracorporeal carbon dioxide removal (ECCO2R) devices have been proposed as new therapeutic option. NIV is an effective strategy in specific settings and in selected population with AHRF. To date, evidence on ECCO2R is based only on case reports and case-control trials. Although the preliminary results using ECCO2R to decrease the rate of NIV failure and to wean hypercapnic patients from invasive ventilation are remarkable; further randomized studies are needed to assess the effects of this technique on both short-term and long-term clinical outcomes.

High-flow therapy (HFT) is the administration of gas flows above 15 L/min. It is a non-invasive respiratory support that delivers heated (up to 38 °C), humidified (100% Relative Humidity, RH; 44 mg H₂O/L Absolute Humidity, AH), oxygen-enriched air when necessary, through a nasal cannula or a tracheostomy interface. Over the last few years, the use of HFT in critically ill hypoxemic adults has increased. Although the clinical benefit of home high-flow therapy (HHFT) remains unclear, some research findings would support the use of HHFT in chronic respiratory diseases. The aim of this review is to describe the HFT physiological principles and summarize the published clinical findings. Finally, we will discuss the differences between hospital and home implementation, as well as the various devices available for HHFT application.

Nasal high flow (NHF) therapy is an established form of non invasive respiratory support used in acute and chronic care. Recently, a new high flow nasal cannula with asymmetric prongs was approved for clinical use. The clinical benefits of the new cannula have not yet been defined and no evidence are available on the use of asymmetric NHF support in patient with Chronic Obstructive Pulmonary Disease (COPD). We conducted a single-centre, prospective, physiologic, crossover, randomised study to investigate the effects on partial pressure of carbon dioxide (PaCO²) levels of two different nasal cannula ("asymmetric" vs "standard" nasal interface) in 20 COPD hypercapnic patients. All patients were recovering from an acute exacerbation that required hospitalisation and had persistent hypercapnia, despite having attained a stable pH. After enrolment, two 90-min trials with the asymmetric nasal high flow interface (Optiflow + Duet, Fisher & Paykel Healthcare Ltd., New Zealand) or the standard interface (Optiflow, Fisher & Paykel Healthcare Ltd., New Zealand) were randomly applied and a washout period of 60 min between the two treatments was performed for minimising the carryover effect. Study results suggested that the asymmetrical cannula did not significantly decrease PaCO² compared with the standard cannula. Similar performances were also observed in terms of diaphragm activity, dyspnoea and patient's comfort. Interestingly, asymmetric NHF cannula performed significantly better in reducing the dead space ventilation and increasing the ventilatory efficiency in more advanced COPD patients with more severe hypercapnia higher baseline PaCO² values (PaCO² ≥ 65 mmHg at baseline). .

Weaning from invasive mechanical ventilation (IMV) is a key element in the management of critically ill patients, encompassing the entire process of discontinuing IMV. Despite its importance, considerable uncertainties remain regarding the optimal strategies to achieve successful weaning. Early weaning is crucial, as IMV is associated with complications related to high mortality rates, such as prolonged weaning and intubation-associated pneumonia (IAP). This review aims to highlight the role of non-invasive respiratory supports (NIRSs), including non-invasive ventilation (NIV) and high-flow nasal cannulas (HFNCs), as a therapeutic bridge between IMV dependency and spontaneous breathing. NIV and HFNCs are recommended to prevent post-extubation respiratory failure (PERF) in high-risk and low-risk patients, respectively, and their combination appears effective in high-risk populations. On the other hand, NIV is not advised in established non-hypercapnic PERF, as it may increase mortality by delaying intubation; however, it can facilitate extubation in patients with hypercapnic respiratory failure. NIRSs may also benefit patients at high risk of post-operative pulmonary complications such as acute respiratory failure (ARF), with either NIV or HFNCs being appropriate. In light of this evidence, appropriate NIRSs selection and application may be pivotal in achieving successful weaning and better outcomes in critically ill patients.