This study aimed to analyze the characteristics of patients who fail high-flow nasal cannula(HFNC) therapy for acute hypoxemic respiratory failure(AHRF) and to identify predictors of treatment failure.

This single-center, retrospective, observational study analyzed clinical data from 388 patients with AHRF. Patients were divided into two groups: the HFNC success group (HFNC-S, n = 256) and the HFNC failure group (HFNC-F, n = 132). The primary endpoint was the need for escalation of respiratory support to tracheal intubation in the enrolled patients. The demographic data, laboratory tests, blood gas analysis data, CT severity scores, and disease severity scores were analysed to determine the difference between patients who were successful and those who failed HFNC treatment. Univariate and multivariate logistic regression models were used to assess potential predictors of failure of HFNC for patients with acute hypoxaemic respiratory failure.

The mean age of patients enrolled was 67.97 ± 14.40 years. The HFNC-F group had significantly higher PSI(Pneumonia Severity Index) score, CURB(Confusion, Urea, Respiratory Rate, Blood Pressure, and Age)-65 score, CPIS(Clinical Pulmonary Infection Score) score, CT score and SOFA(Sequential Organ Failure Assessment) scores compared to the HFNC-S group. Within 12 h of the initiation of treatment, the HFNC-F group exhibited significantly lower oxygen saturation index (PaO2/FiO2) and significantly higher respiratory rate. Additionally, the HFNC-F group exhibited significantly higher levels of C-reactive protein (CRP), platelet count (PLT), D-dimer, interleukin-10 (IL-10), total bilirubin (TB) and creatinine (CB), but lower albumin levels. Multivariate analysis identified CT score, SOFA score, interleukin-1β (IL-1β), and albumin as independent predictors of HFNC failure.

HFNC is effective for treating AHRF. CT score, SOFA score, IL-1β, and albumin are independent predictors of HFNC failure.

The effect of combining high fraction of inspired oxygen (FIO2) and high flow through a high-flow nasal cannula (HFNC) on exercise tolerance in chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) remains unclear.

This prospective, single-blind, randomized, crossover study included patients with COPD (n = 25) and IPF (n = 25). The patients performed a 6-min walking test (6 MWT) while attached to a battery-supplied portable HFNC device under the following four conditions: FIO2 set to a minimum percutaneous oxygen saturation (SpO2) of 86-88 % during 6 MWT with a flow rate of 10 L/min (LOLF) or 50 L/min (LOHF); and FIO2 set to a minimum SpO2 of 92-94 % with a flow rate of 10 L/min (HOLF) or 50 L/min (HOHF).

In both groups, the 6-min walking distance (6 MWD) was significantly greater for HOHF than for LOLF (COPD: 323.2 ± 77.6 m vs. 268.6 ± 87.3 m, respectively, p < 0.0001 and IPF: 406 ± 50.7 m vs. 372.3 ± 50.9 m, respectively, p < 0.0001). In the analysis of the interaction effects for the 6 MWD, the combination of high FIO2 and high flow resulted in an additional 15.9-m extension of the 6 MWD (95 % confidence interval: 0.34-31.5; p = 0.050). The interaction between IPF and high-flow was -14.0 m, suggesting a less pronounced extension effect compared with COPD (95 % confidence interval: -29.5-1.6; p = 0.085).

The combination of high FIO2 and high flow through an HFNC may improve exercise tolerance in patients with COPD and IPF.

The use of high flow nasal oxygen (HFNO) in clinical practice is increasing with robust evidence of its respiratory benefits. Swallowing is known to be heavily coordinated with breathing, in addition to sharing a physical pathway in the upper airway. Applying HFNO via these spaces may also have an impact on the swallowing process. Yet, there is a lack of literature regarding the effect of HFNO on swallowing and on dysphagia. This narrative review aims to summarise the existing literature, draw conclusions on important clinical questions where possible and set the scene for future research. A database search was conducted on 24/01/2024 across CINAHL, Medline and Embase. Due to paucity of literature, studies with adult participants within and outside of ICU were included, and references cross-checked. Conference abstracts were also included. The search was repeated on 5/6/2024. Twelve articles were included in direct data comparison, in addition to studies examining the biomedical effect of HFNO that is, the impact of HFNO on the physiology of the oropharynx and swallow function. The authors conclude that whilst studies are limited in numbers and some results controversial, indications are that HFNO may demand adaptations to swallowing and some patients may not have this capability to adapt. HFNO should not be a barrier to a swallow assessment, irrespective of flow rate and the decision to assess should be based on overall patient presentation, as with any other population. Instrumental swallowing assessment is recommended to confirm any detrimental or beneficial impact of HFNO on swallow function. Robust research and guidelines are needed.

High-flow nasal cannula (HFNC) is a noninvasive respiratory support system that delivers air that is heated at 31°C-38°C, humidified 100%, and oxygen-enriched at a constant high flow rate of 15-60 L/min. Because of its numerous physiological benefits, convenience, and minimal side effects, HFNC has been increasingly used over the past decade in patients with acute hypoxemic respiratory failure, yet the clinical benefits of long-term HFNC remain uncertain. Several studies have suggested its potential use as an alternative home oxygen therapy for patients with chronic stable lung diseases, such as chronic obstructive pulmonary disease (COPD), interstitial lung disease, and bronchiectasis. The use of long-term home HFNC in patients with chronic respiratory failure is an emerging area with promising potential. Despite limited clinical research, this review aims to describe the physiology of HFNC use and summarize the current evidence on its long-term application, to provide healthcare providers with insights and perspectives on the potential role of long-term home HFNC.

In recent years, several studies have examined the impact of sleep-disordered breathing (SBD) on the quality of life and prognosis of patients with idiopathic pulmonary fibrosis (IPF). Among these disorders, obstructive sleep apnea (OSA) and nocturnal hypoxemia (NH) are the most prevalent and extensively studied, whereas central sleep apnea (CSA) has only been documented in recent research. The mechanisms underlying the relationship between IPF and SBDs are complex and remain an area of active investigation. Despite growing recognition of SBDs in IPF, no standardized guidelines exist for their management and treatment, particularly in a population characterized by distinct structural pulmonary abnormalities. This review outlines the pathophysiological connections between sleep-breathing disorders (SBDs) and idiopathic pulmonary fibrosis (IPF), as well as current therapeutic options. A comprehensive literature search using PubMed identified relevant studies, confirming the efficacy of CPAP in treating severe OSA and CSA. While high-flow oxygen therapy has not been validated in this patient cohort, it may offer a potential solution for select patients, particularly the elderly and those with low compliance. Conventional oxygen therapy, however, is limited to cases of isolated nocturnal hypoxemia or mild central sleep apnea.

Exertional dyspnea and exercise intolerance remain key patient-related outcomes in chronic obstructive pulmonary disease (COPD). Improvement in treatment strategies is pendant further understand of their underpinnings across the spectrum of disease severity.

Emerging literature has been reviewed based on a conceptual framework that relates ventilatory demand to capacity under the modulating influence of sub-cortical and cortical centers (symptom perception and affective interpretation). Evidence supporting these fundamental tenets is critically appraised, focusing on mechanistic and interventional studies that shed novel light on the sources of heightened and/or mechanically constrained ventilation. Mechanistic studies using proxies of the inspiratory neural drive (e.g., diaphragm electromyography) were particularly informative, as well as interventional trials aimed at decreasing afferent stimulation and/or symptom perception via pharmacological (e.g., low-dose opiates in selected patients, high flow oxygen, oral nitrate) and nonpharmacological (e.g., novel exercise training paradigms, inspiratory muscle training, breathing techniques) interventions.

Therapeutic and rehabilitative strategies to lessen dyspnea's devastating impact on quality of life should minimize demand in the setting of reduced capacity and increased sensation awareness in COPD. The most successful attempts so far have amalgamated pharmacological and nonpharmacological approaches tailored to the main underlying mechanisms on an individual basis.

Background: Chronic Obstructive Pulmonary Disease (COPD) is a disease with high morbidity and mortality globally. Exacerbations of COPD are major contributors to disease progression and a decline in health-related quality of life (HRQoL). High-flow nasal cannula (HFNC) oxygen therapy is an innovative therapy that provides humidified and heated blended air and oxygen through a nasal cannula. There is some preliminary evidence supporting the effectiveness of HFNC in managing COPD exacerbations, but there are limited data on its effectiveness when used at home for patients with stable, severe COPD. The aim of the present study is to test the hypothesis that home HFNC can decrease the COPD exacerbations rate and hospital admissions and improve HRQoL measures in severe COPD patients with frequent COPD exacerbations. Methods: In a prospective proof-of-concept interventional multicenter study, 40 GOLD stage III and IV COPD patients with a high disease burden (≥2 exacerbations treated with antibiotics and/or corticosteroids) and ≥1 hospital admission in the last year were included. Patients were given instructions on the usage of HFNC by a ventilation practitioner during a group session. The flow rate was 25-30 L/min and FiO2 was 21-35%. Outcome measures included the COPD exacerbations rate, hospital admissions, in-hospital days, Medical Research Council dyspnea (MRC) score, Clinical COPD Questionnaire (CCQ) score, Hospital Anxiety Depression Scale (HADS) scores and capillary pCO2. Repeated analysis of variance (ANOVA) was used to analyze the data. Significant effects identified in the ANOVA were further examined using Student's t-tests. Results: After 1 year, 27 patients could be evaluated. The COPD exacerbations rate decreased by 1.40 (mean difference ± SD: 1.40 ± 2.09; p = 0.002), hospital admissions decreased by 0.96 admissions per year (0.96 ± 1.37; p = 0.001), and in-hospital days decreased by 7.22 days (7.22 ± 9.26; p = 0.001). Capillary pCO2 decreased by 0.02 kPa (0.02 ± 0.52; p = 0.85). The CCQ score decreased by 0.06 (0.06 ± 0.96; p = 0.76). The MRC dyspnea score decreased by 0.04 (0.04 ± 0.80; p = 0.81). The HADS anxiety score decreased by 0.63 (0.63 ± 3.12; p = 0.31). And finally, the HADS depression score decreased by 0.32 (0.32 ± 3.48; p = 0.64). There was a significant difference between the normocapnic (capillary pCO2 < 6.0 kPa) group and the hypercapnic group in terms of change in the CCQ score (-0.24 ± 0.55 and 0.49 ± 1.32 decrease, respectively, p = 0.05) and the HADS depression score (-0.76 ± 1.86 and 2.20 ± 4.75 decrease, respectively, p = 0.03) after 1 year of HFNC treatment. Conclusions: One-year-long HFNC therapy significantly decreased the COPD exacerbations rate, hospital admissions, and in-hospital days in severe COPD patients with a high disease burden and frequent COPD exacerbations irrespective of them having hypercapnia and with the HRQoL measures only improving in the hypercapnic group. This may imply that severe COPD patients with a high disease burden and frequent COPD exacerbations, irrespective being hypercapnic, are candidates for treatment with home HFNC oxygen therapy.

Pulmonary arterial hypertension (PAH) is a unique disease process with a highly complex physiology. Patients with PAH are often on specialized medications that exert specific hemodynamic effects. Furthermore, when they become critically ill, the management strategy can be counterintuitive. Commonly accepted, evidence-based management for the general population, such as fluid boluses in the setting of sepsis, can be harmful to this patient cohort. Often, these patients require highly specialized care at tertiary and quaternary centers, which necessitates critical care transport. Therefore, it is important that critical care transport crews understand the distinctive pathophysiology and management of critically ill patients with PAH.

The use of high-flow nasal cannulas (HFNC) in patients admitted to the pediatric intensive care unit (PICU) has gradually increased worldwide; however, details on clinical efficacy remain limited in Taiwan. Therefore, we explored the clinical characteristics and outcomes of pediatric patients using HFNC in the PICU.

Medical records were retrospectively collected from pediatric patients (aged <18 years) who received HFNC support from December 2021 to January 2023 in the PICU of a medical center. Outcome parameters included treatment failure (defined as increased respiratory support to advanced non-invasive ventilators or intubations), duration of support from HFNC, and changes in clinical parameters after initiating HFNC.

A total of 261 episodes of HFNC use were included, with a failure rate of 24.5% and a median support length of 4 days. Multivariable analysis showed that infant age (adjusted odds ratio [aOR]: 2.1, p = 0.02) and accompanying complex chronic disease (aOR: 4.4, p = 0.014) were risk factors for treatment failure and a diagnosis of asthma or bronchiolitis had a lower hazard of treatment failure (aOR: 0.29, p = 0.025) than other diagnoses did. Improvements in clinical parameters, including pulse rate, respiratory rate, SpO2, and CO2 levels, were observed 24 h after the initiation of HFNC.

The application of HFNC in the PICU in Taiwan is effective but should be performed with care in infants with accompanying complex chronic diseases. In addition to low treatment failure, HFNC utilizations stabilized the clinical parameters of children with asthma/bronchiolitis within one day.

High-flow nasal cannula (HFNC) has increased exercise capacity in patients with chronic respiratory diseases. However, it remains unknown whether HFNC impacts respiratory physiological variables during exercise. This study aimed to evaluate the effect of HFNC on respiratory physiological variables during sustained high-intensity exercise in healthy volunteers.

We performed a single-centre, open-label, randomised crossover trial to compare HFNC (60 L·min-1) and Sham-HFNC (2 L·min-1) interventions during a constant work rate exercise (CWRET) through randomised order. The primary outcome was change in oesophageal pressure (ΔP oes), and the secondary outcomes were other variables of inspiratory effort, ventilation distribution, ventilatory variables and clinical assessment. We evaluated volunteers at seven time points (baseline=T0; CWRET=T1-T2-T3 (1, 4 and 6 min); cooldown period=T4-T5-T6 (1, 6 and 10 min)) in both interventions.

14 healthy volunteers (50% women; age: 22 (21-27) years) were enrolled. Mean differences in ΔP oes decreased to favour the HFNC intervention compared to Sham-HFNC at T2 (-2.8 cmH2O; 95% CI -5.3 to -0.3), as well as the simplified oesophageal pressure-time product (sPTP) per minute at T2 (-86.1 cmH2O·s·min-1; 95% CI -146.2 to -26.1) and T3 (-79.9 cmH2O·s·min-1; 95% CI -142.3 to -17.6). The standard deviation of the Regional Ventilation Delay index was also lower with HFNC compared to Sham-HFNC (T1: -1.38; 95% CI -1.93 to -0.83; T2: -0.71; 95% CI -1.27 to -0.16). There was decreased dyspnoea to favour the HFNC, but sPTP per breath, spatial distribution ventilation indexes, ventilatory variables and clinical assessments were nonsignificant between interventions.

HFNC intervention reduces respiratory effort and dyspnoea and improves temporal ventilation distribution in healthy volunteers during CWRET.

General anesthesia is a critical component of surgical procedures, requiring effective ventilation strategies to ensure adequate oxygenation and prevent complications. This narrative review aims to compare various ventilation techniques used during general anesthesia, focusing on their physiological foundations, clinical applications, and outcomes. Traditional methods, such as high tidal volume ventilation, have evolved into more sophisticated approaches, including protective lung ventilation, which are particularly beneficial for high-risk patients with respiratory comorbidities. The review highlights that protective lung ventilation, characterized by lower tidal volumes and optimal positive end-expiratory pressure, is associated with improved oxygenation, reduced incidence of post-operative pulmonary complications, and enhanced overall recovery. Despite the advantages of personalized ventilation approaches, current evidence remains limited by small sample sizes and variability in study designs. This underscores the need for larger, randomized controlled trials to establish definitive guidelines. Future research should also explore emerging technologies to optimize the real-time management of ventilation parameters. The findings emphasize the importance of individualized ventilation strategies in clinical practice to improve patient outcomes and inform policy development. By advancing our understanding of ventilation techniques, this review aims to contribute to safer anesthesia practices and enhance recovery in surgical patients.

High-flow nasal oxygen (HFNO) therapy delivers humidified, heated air with flow rates of up to 60 L/min with oxygen entrained. HFNO has advantages over conventional oxygen therapy, including precise and reliable fraction of inspired oxygen delivery, therefore is recommended as first-line treatment for people with acute hypoxaemic respiratory failure.

This pilot study aimed to determine the feasibility and acceptability of domiciliary nasal high flow (NHF) without entrained oxygen for people with chronic obstructive pulmonary disease (COPD) and severe breathlessness.

Single-arm, mixed-methods, pilot study of an 8-day, air-only NHF intervention in adults with COPD and severe breathlessness not requiring domiciliary oxygen therapy.

Participants were educated and advised to use NHF for ⩾7 h per night for 7 nights with day use as desired. Patient-reported outcome measures were assessed on Days 3, 5 and 8.

feasibility.

breathlessness (dyspnoea), fatigue, quality of life, physical function, sleep, tolerability and safety. Acceptability was also assessed through semi-structured interviews.

Fifteen participants were enrolled (mean age 73.6; 40% women; mean FEV1 41% predicted, mean DLCO 43.0% predicted; mean modified Medical Research Council score 3.7). Thirteen (87%) completed the trial, with 8 (54%) keeping the device at the end of the trial and 3 (20%) continuing use long-term. Adherence varied, with average daily usage higher amongst participants who kept the device compared to those who returned it (6.8 h ± 2.3 h vs 3.4 h ± 3.7 h). No changes in worst breathlessness (mean = 0.7, SD = 1.2, p = 0.109), dyspnoea mastery (mean = 0.3, SD = 0.6, p = 0.176) or fatigue (mean = 0.0, SD = 2.4, p = 1.00) were observed at Day 8 compared to baseline. No significant adverse events were reported. Qualitative interviews demonstrated subjective improvements in breathlessness, dry mouth and sputum production for some participants, whilst others found NHF uncomfortable. Fear of NHF dependence and concerns regarding long-term running costs were reported.

Domiciliary NHF was a feasible intervention, albeit with varied adoption and acceptability. These trial implementation outcomes may have affected preliminary effectiveness outcomes. Further research is required to determine what role domiciliary NHF may have for people with COPD and severe breathlessness.

ACTRN12621000044820.

Introduction: In normal subjects, during tidal breathing, aerosols deposit by settling in small airways. With obstructive lung disease (OLD), collapse of airways during expiration causes turbulence and increased deposition in central airways. High-flow nasal cannula (HFNC) therapy, washing out dead space, may affect deposition mechanisms and drug delivery. This study compared aerosol deposition and airway responsiveness in OLD after traditional and HFNC nebulization therapy. Methods: Twelve subjects with moderate to severe OLD participated in a two-day study. Spirometry was measured pre- and post-aerosol inhalation. On Day 1 (D1) subjects tidally inhaled radiolabeled albuterol (99mTc DTPA) by mouth via AeroTech II, (Biodex. Shirley, NY). Day 2 (D2) inhalation was via HFNC using i-AIRE (InspiRx, Inc. Somerset, NJ). The HFNC system (60 L/m) was infused by syringe pump at 50 mL/h. D2 lung deposition was monitored in real time by gamma camera to match D1. Pre and post heart rate, O2 sat, and nasopharyngeal deposition (NP) were measured. Mechanistic contributions were modeled using multiple linear regression (MLR) of deposition rate (DR µg/m) as a function of breathing frequency, airway geometry (FEV1), and parenchymal integrity (DLCO). Results: Albuterol lung depositions were matched (p = 0.13) with D1 central/peripheral (sC/P) ratios 1.99 ± 0.98. Following HFNC, peripheral deposition increased (31% ± 33%, sC/P = 1.51 ± 0.43, p = 0.01). D2/D1% change FVC increased by 16.1 ± 16.7% (p = 0.003). NP deposition averaged 333% of lung. Heart rate and O2 sat were unaffected (p = 0.31, p = 0.63 respectively). DR analysis was markedly different between D1 (R2 = 0.82) and D2 (R2 = 0.12). Conclusion: In subjects with OLD, HFNC nebulization at 60 L/min was well tolerated and increased peripheral drug delivery. Spirometry significantly improved. Systemic effects were undetected indicating limited nasal absorption. MLR demonstrated that different mechanisms of deposition govern traditional vs HFNC aerosol delivery. Breath-enhanced nebulization via HFNC may provide controllable and effective aerosol therapy in OLD.

Acute respiratory failure is the leading cause of intensive care unit (ICU) admission of cancer patients. Studies of the efficacy of high-flow nasal cannula (HFNC) therapy were rarely conducted in cancer populations. We here compared the clinical effects of HFNC therapy and conventional oxygen therapy (COT) in cancer patients with concurrent acute hypoxemic respiratory failure (AHRF). In this single-center retrospective study, cancer patients with concurrent acute hypoxic respiratory failure either received initial oxygen therapy via HFNC (HFNC group, 68 patients) or received initial oxygen therapy via a nasal cannula, simple mask, or mask with reservoir bag (COT group, 133 patients). Groups were propensity score matched. Differences in respiratory rate (RR), heart rate (HR), and PaO2/FiO2 ratio before and after treatment in the two groups were compared using a mixed-effects model. The 28-day mortality risk was explored using a Cox proportional hazards model. The 24-h and 48-h PaO2/FIO2 ratios were significantly higher in the HFNC than in the COT group (210.5 mmHg vs. 178.5 mmHg; P < 0.01; 217.1 mm Hg vs. 181.6 mm Hg; P < 0.01, respectively). Differences in RR and HR between the groups at each time point were nonsignificant. The 28-day mortality rate was 17.4% vs. 38.1% for the HFNC and COT groups, respectively (P < 0.01). Hazard ratio was significantly higher for COT group (HR 2.6, 95% confidence interval 1.3, 5.3). Compared with COT, HFNC use for initial oxygen therapy can improve PaO2/FIO2 ratio and survival rate in cancer patients with AHRF.

Humidified high-flow nasal oxygen therapy (HFNO) has, in recent years, come to assume a key role in the management of hypoxemic acute respiratory failure (ARF). While non-invasive ventilation (NIV) currently represents the first-line ventilatory strategy in patients exhibiting hypercapnic ARF, the operating principles and physiological effects of HFNO could be interesting and useful in the initial management of hypercapnic ARF and/or after extubation, particularly in acute exacerbations of chronic obstructive pulmonary disease. Under these conditions, HFNO could be used either alone continuously or in combination with NIV during breaks in spontaneous breathing, depending on the severity and etiology of the underlying hypercapnic ARF.

To assess the efficacy and safety of high-flow nasal cannula (HFNC) in elderly patients with acute respiratory failure (ARF) not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) and without criteria for admission to intensive care units (ICU).

Prospective observational study of patients with ARF treated with HFNC who presented clinical and arterial blood gas deterioration after 24 h of medical treatment and oxygenation by conventional systems. The degree of dyspnoea, gas exchange parameters (arterial O2 pressure/inspired O2 fraction ratio (PaO2/FiO2); oxygen saturation measured by oximetry/ inspired fraction of oxygen (Sp02/Fi02), ROX index), degree of patient tolerance and mortality were evaluated. These were measured at discharge from the emergency department (ED), 24 h after treatment with conventional oxygenation and 60, 120 min and 24 h after initiation of HFNC. The results were analyzed for all patients as a whole and for patients with hypercapnia (arterial carbon dioxide tension (PaCO2) < 45 mmHg) separately.

200 patients were included in the study between November 2019 and November 2020, with a mean age of 83 years, predominantly women (61.9%), obese (Body Mass Index (BMI) 31.1), with high comorbidity (Charlson index 4) and mild-moderate degree of dependence (Barthel 60). A number of 128 patients (64%) were hypercapnic. None had respiratory acidosis (pH 7.39). Evaluation at 60 min, 120 min and 24 h showed significant improvement in all patients and in the subgroup of hypercapnic patients with respect to baseline parameters in respiratory rate (RR), dyspnoea, ROX index, PaO2/FiO2, SpO2/FiO2 and patient comfort. No changes in PaCO2 or level of consciousness were observed. HFNC was well tolerated. Ten patients (5%) died due to progression of the disease causing ARF.

HFNC is an effective and safe alternative in elderly patients with ARF not due to COVID-19, refractory to treatment with conventional oxygen therapy and/or intolerant to NIV or CPAP and without criteria for admission to ICU.

How to cite this article: Pachisia AV, Govil D. High Flow, High Hope: HFNO in Acute Hypoxemic Respiratory Failure. Indian J Crit Care Med 2024;28(8):726-728.

 High-flow nasal cannula (HFNC) oxygenation has emerged as a convenient and handy oxygenation mode over the past few years, especially during the COVID-19 pandemic. HFNC is designed to provide humidified oxygen at high flow rates to subjects in a much more patient-compliant method. Noninvasive ventilation (NIV) has been a powerful tool in treating dyspneic patients of different etiologies, yielding positive outcomes over many decades. HFNC has the potential to serve as an alternative to NIV for acutely breathless patients, offering better patient compliance.

 A prospective observational study was conducted with a population size of 100 patients. The patients were randomly assigned to HFNC and NIV groups and further compared based on the clinical criteria, arterial oxygen pressure (PaO2)/fraction of inspired oxygen (FiO2) ratios, and modified Borg score. Simple proportions, mean, standard deviation, and chi-square tests were used. The chi-square test was applied to determine the association between the two attributes.

 Both HFNC and NIV subset populations have shown substantial improvement in their clinical criteria in terms of respiratory rate, heart rate, oxygen saturation, PaO2/FiO2 ratios, and modified Borg score over two and six hours with statistically significant improvement in oxygen saturations among HFNC subset in comparison to NIV subset (at two hours, p = 0.004; at six hours, p = 0.022). Secondary outcomes like the need for intubation (14% in HFNC, 22% in NIV) and mortality (4% in HFNC, 6% in NIV group) were noted, which were statistically insignificant in comparing their efficacy.

 The study concluded that HFNC resulted in better clinical parameters than NIV, but the difference was statistically insignificant except for oxygen saturation. Similarly, HFNC resulted in a decreased need for intubation and less mortality compared to NIV.

The failure of high-flow nasal cannula (HFNC) oxygen therapy can necessitate endotracheal intubation in patients, making timely prediction of the intubation risk following HFNC therapy crucial for reducing mortality due to delays in intubation.

To investigate the accuracy of ChatGPT in predicting the endotracheal intubation risk within 48 h following HFNC therapy and compare it with the predictive accuracy of specialist and non-specialist physicians.

We conducted a prospective multicenter cohort study based on the data of 71 adult patients who received HFNC therapy. For each patient, their baseline data and physiological parameters after 6-h HFNC therapy were recorded to create a 6-alternative-forced-choice questionnaire that asked participants to predict the 48-h endotracheal intubation risk using scale options ranging from 1 to 6, with higher scores indicating a greater risk. GPT-3.5, GPT-4.0, respiratory and critical care specialist physicians and non-specialist physicians completed the same questionnaires (N = 71) respectively. We then determined the optimal diagnostic cutoff point, using the Youden index, for each predictor and 6-h ROX index, and compared their predictive performance using receiver operating characteristic (ROC) analysis.

The optimal diagnostic cutoff points were determined to be ≥ 4 for both GPT-4.0 and specialist physicians. GPT-4.0 demonstrated a precision of 76.1 %, with a specificity of 78.6 % (95%CI = 52.4-92.4 %) and sensitivity of 75.4 % (95%CI = 62.9-84.8 %). In comparison, the precision of specialist physicians was 80.3 %, with a specificity of 71.4 % (95%CI = 45.4-88.3 %) and sensitivity of 82.5 % (95%CI = 70.6-90.2 %). For GPT-3.5 and non-specialist physicians, the optimal diagnostic cutoff points were ≥5, with precisions of 73.2 % and 64.8 %, respectively. The area under the curve (AUC) in ROC analysis for GPT-4.0 was 0.821 (95%CI = 0.698-0.943), which was the highest among the predictors and significantly higher than that of non-specialist physicians [0.662 (95%CI = 0.518-0.805), P = 0.011].

GPT-4.0 achieves an accuracy level comparable to specialist physicians in predicting the 48-h endotracheal intubation risk following HFNC therapy, based on patient baseline data and physiological parameters after 6-h HFNC therapy.

Interstitial lung disease (ILD) is characterized by dyspnoea on exertion and exercise-induced hypoxaemia. High-flow nasal cannula (HFNC) therapy reduces the respiratory workload through higher gas flow and oxygen supplementation, which may affect exercise tolerance. This study aimed to examine the effects of oxygen and gas flow rates through HFNC therapy on exercise tolerance in ILD patients.

We conducted three-treatment crossover study. All ILD patients performed the exercises on room air (ROOM AIR setting: flow, 0 L/min; fraction of inspired oxygen [FiO2], 0.21), HFNC (FLOW setting: flow 40 L/min, FiO2 0.21), and HFNC with oxygen supplementation (FLOW + OXYGEN setting: flow 40 L/min, FiO2 0.6). The primary endpoint was the endurance time, measured using constant-load cycle ergometry exercise testing at a peak work rate of 80%.

Twenty-five participants (10 men, 71.2 ± 6.7 years) were enrolled. The increase in exercise duration between the ROOM AIR and FLOW was 46.3 s (95% CI, -6.1 to 98.7; p = 0.083), and the FLOW and FLOW + OXYGEN was 91.5 s (39.1-143.9; p < 0.001). The percutaneous oxygen saturation (SpO2) at rest was significantly higher with the FLOW + OXYGEN setting than with the ROOM AIR and FLOW settings, and the difference persisted during exercise. At equivalent time points during exercise, the SpO2 with the FLOW setting was significantly higher than that with the ROOM AIR setting.

Oxygen supplementation in HFNC therapy improved exercise tolerance and SpO2. We found that gas flow alone did not improve exercise tolerance, but improved SpO2 during exercise.

Background: High-flow nasal cannula (HFNC) therapy has emerged as a promising treatment modality for interstitial lung disease (ILD)-related respiratory failure. This systematic review aims to evaluate the efficacy and safety of HFNC therapy in patients with ILDs. Methods: A comprehensive literature search was conducted using major electronic databases to identify relevant studies investigating the use of HFNC therapy in ILD patients with respiratory failure. Outcome measures of interest included improvements in oxygenation, dyspnea relief, respiratory rate control, hospital length of stay, and mortality. Results: Twelve studies were analyzed with an overall population of 715 patients included. Idiopathic Pulmonary Fibrosis (IPF) was the most prevalent type of ILD. Evaluated clinical settings were acute (7 studies), chronic (2 studies), and end-stage (3 studies) ILDs. The HFNC as a support for acute respiratory failure seems not inferior to non-invasive ventilation while offering better comfort and patient's perception. Poor data are available about use in chronic/long-term or rehabilitative settings. In end of life/palliative care, an HFNC might improve quality of life. Despite the promising results, further research is warranted to establish optimal HFNC protocols, identify patient subgroups most likely to benefit, and explore long-term outcomes. Conclusions: Overall, the HFNC appears to be a valuable therapeutic option for managing respiratory failure in ILD patients, offering potential improvements in oxygenation and symptom relief.

Transnasal humidified rapid-insufflation ventilator exchange (THRIVE) has been reported to have better efficacy during anesthesia induction compared to conventional mask ventilation, including improved oxygenation and prolonged safe apnea time. This study reports on the effectiveness of the THRIVE system during modified electroconvulsive therapy (mECT) for a patient experiencing severe hypoxia. A 78-year-old female patient with bipolar disorder received maintenance mECT every four weeks. She previously experienced a significant hypoxic event, with oxygen saturation (SpO2) dropping to 50% following electrical stimulation. In response, we employed the THRIVE system, designed to deliver high-flow, 100% oxygen, thereby extending apnea tolerance. The implementation of THRIVE ensured a stable oxygen supply, maintaining oxygen saturation levels above 95% throughout the mECT procedure. THRIVE is useful for treating hypoxia that occurs due to the unavoidable lack of ventilation during mECT.

Compared to conventional oxygen devices, high-flow oxygen treatment (HFOT) through the nasal cannulae has demonstrated clinical benefits. Limited data exist on whether such effects are also present in HFOT through tracheostomy. Hence, we aimed to examine the short-term effects of HFOT through tracheostomy on diaphragmatic function and respiratory parameters in tracheostomized patients on prolonged mechanical ventilation.

A randomized, crossover, physiological study was conducted in our ICU between December 2020 and April 2021, in patients with tracheostomy and prolonged mechanical ventilation. The patients underwent a 30-min spontaneous breathing trial (SBT) and received oxygen either via T-piece or by HFOT through tracheostomy, followed by a washout period of 15-min breathing through the T-piece and receipt of 30-min oxygen with the other modality in a randomized crossover manner. At the start and end of each session, blood gasses, breathing frequency (f), and tidal volume (VT) via a Wright's spirometer were measured, along with diaphragm ultrasonography including diaphragm excursion and diaphragmatic thickening fraction, which expressed the inspiratory muscle effort.

Eleven patients were enrolled in whom 19 sessions were uneventfully completed; eight patients were studied twice on two different days with alternate sessions; and three patients were studied once. Patients were randomly assigned to start the SBT with a T-piece (n=10 sessions) or with HFOT (n=9 sessions). With HFOT, VT and minute ventilation (VE) significantly increased during SBT (from [465±119] mL to [549±134] mL, P <0.001 and from [12.4±4.3] L/min to [13.1±4.2] L/min, P <0.05, respectively), but they did not change significantly during SBT with T-piece (from [495±132] mL to [461±123] mL and from [12.8±4.4] mL to [12.0±4.4] mL, respectively); f/VT decreased during HFOT (from [64±31] breaths/(min∙L) to [49±24] breaths/(min∙L), P <0.001), but it did not change significantly during SBT with T-piece (from [59±28] breaths/(min∙L) to [64±33] breaths/(min∙L)); partial pressure of arterial oxygen increased during HFOT (from [99±39] mmHg to [132±48] mmHg, P <0.001), but it decreased during SBT with T-piece (from [124±50] mmHg to [83±22] mmHg, P <0.01). In addition, with HFOT, diaphragmatic excursion increased (from [12.9±3.3] mm to [15.7±4.4] mm, P <0.001), but it did not change significantly during SBT with T-piece (from [13.4±3.3] mm to [13.6±3.3] mm). The diaphragmatic thickening fraction did not change during SBT either with T-piece or with HFOT.

In patients with prolonged mechanical ventilation, HFOT through tracheostomy compared with T-piece improves ventilation, pattern of breathing, and oxygenation without increasing the inspiratory muscle effort.

Clinicaltrials.gov ldentifer: NCT04758910.

Patients requiring mechanical ventilation (MV) beyond 21 days, usually referred to as prolonged MV, represent a unique group with significant medical needs and a generally poor prognosis. Research suggests that approximately 10% of all MV patients will need prolonged ventilatory care, and that number will continue to rise. Although we have extensive knowledge of MV in the acute care setting, less is known about care in the post-ICU setting. More than 50% of patients who were deemed unweanable in the ICU will be liberated from MV in the post-acute setting. Prolonged MV also presents a challenge in care for medically complex, elderly, socioeconomically disadvantaged and marginalized individuals, usually at the end of their life. Patients and their families often rely on ventilator weaning facilities and skilled nursing homes for the continuation of care, but home ventilation is becoming more common. The focus of this review is to discuss recent advances in the weaning strategies in prolonged MV, present their outcomes and provide insight into the complexity of care.

To evaluate the efficacy of high-flow nasal cannula oxygenation (HFNC) versus non-invasive ventilation (NIV) in pediatric patients post-congenital heart surgery (CHS) through a meta-analysis.

A comprehensive literature search was conducted across the Chinese biomedical literature database, Vip database, CNKI, Wanfang, PubMed, Embase, Cochrane Library, and Web of Science until December 20, 2022. We selected RCTs or cohort studies that met inclusion criteria for a meta-analysis using RevMan 5.4 software.

Our search yielded five publications, comprised of one randomized controlled trial and four cohort studies. Meta-analysis revealed a significant reduction in reintubation rates in children post-CHS treated with HFNC as compared to NIV [RR = 0.36, 95%CI(0.25 ~ 0.53), P < 0.00001]. There was also a notable reduction in the duration of ICU stay [MD = -4.75, 95%CI (-9.38 ~ -0.12), P = 0.04]. No statistically significant differences were observed between HFNC and NIV in terms of duration of mechanical ventilation, 24 h PaO2, and PaCO2 post-treatment (P > 0.05). Furthermore, both groups showed no significant difference in the duration of extracorporeal circulation [MD = -8.27, 95%CI(-17.16 ~ 0.62), P = 0.07].

For pediatric patients post-CHS, HFNC appears to be more effective than NIV in reducing reintubation rates and shortening the CICU stay.

Hypoxia is a frequently reported complication during the intubation procedure in the emergency department (ED) and may cause bad outcomes. Therefore, oxygenation plays an important role in emergency airway management. The efficacy of oxygenation with high-flow nasal cannula (HFNC) in the ED has been studied, though the evidence is limited. The study aim was to compare two methods of preoxygenation in patients undergoing rapid sequence intubation (RSI) in the ED: (1) HFNC and (2) bag-valve mask (BVM) oxygenation.

This is a single-center, prospective, randomized controlled trial (RCT) in adult ED patients requiring RSI. Patients were randomized to receive preoxygenation with either HFNC or BVM. While HFNC therapy was continued during the intubation procedure, BVM oxygenation was interrupted for laryngoscopy. The primary outcome was the lowest peripheral oxygen saturation (SpO2) level during intubation. Secondary outcomes were incidence of desaturation (SpO2<90%) and severe hypoxemia (SpO2<80%) throughout the procedure, intubation time, rate of failed intubation, and 30-day survival rates.

A total of 135 patients were randomized into two groups (HFNC n = 68; BVM n = 67). The median lowest SpO2 value measured during intubation was 96% (88.8%-99.0%) in the HFNC group and 92% (86.0%-97.5%) in the BVM group (P = .161). During the intubation procedure, severe hypoxemia occurred in 13.2% (n = 9) of patients in the HFNC group and 8.9% (n = 6) in the BVM group, while mild hypoxemia was observed in 35.8% (n = 24) of the BVM group and 26.5% (n = 18) of the HFNC group. However, there was no statistically significant difference between the groups in terms of hypoxemia development (P = .429 and P = .241, respectively). No significant difference was reported in the rate of failed intubation between the groups. Thirty-day mortality was observed in 73.1% of the BVM group and 57.4% of the HFNC group, with a borderline statistically significant difference (difference 15.7; 95% CI of the difference: -0.4 to 30.7; P = .054).

The use of HFNC for preoxygenation, when compared to standard care with BVM oxygenation, did not improve the lowest SpO2 levels during intubation. Also, the use of HFNC during intubation did not provide benefits in reducing the incidence of severe hypoxemia. However, the 30-day survival rates were slightly better in the HFNC group compared to the BVM group.

High-flow nasal cannula (HFNC) and conventional oxygen therapy (COT) are important respiratory support strategies for acute hypoxemic respiratory failure (AHRF) in coronavirus disease 2019 (COVID-19) patients. However, the results are conflicting for the risk of intubation with HFNC as compared to COT.

We systematically synthesized the outcomes of HFNC relative to COT in COVID-19 patients with AHRF and evaluated these outcomes in relevant subpopulations.

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

We searched PubMed, EMBASE, Web of Science, Scopus, ClinicalTrials.gov, medRxiv, BioRxiv, and the Cochrane Central Register of Controlled Trials for randomized controlled trials and observational studies that compared the efficacy of HFNC with COT in patients with COVID-19-related AHRF. Primary outcomes were intubation rate and mortality rate. Secondary outcomes were the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2), respiratory rate, hospital length of stay, intensive care unit (ICU) length of stay, and days free from invasive mechanical ventilation.

In total, 20 studies with 5732 patients were included. We found a decreased risk of requiring intubation in HFNC compared to COT [odds ratio (OR) = 0.61, 95% confidence interval (CI): 0.46-0.82, p = 0.0009, I2 = 75%]. Similarly, we found HFNC was associated with lower risk of intubation rate compared to COT in the subgroup of patients with baseline PaO2/FiO2 < 200 mmHg (OR = 0.69, 95% CI: 0.55-0.86, p = 0.0007, I2 = 45%), and who were in ICU settings at enrollment (OR = 0.57, 95% CI: 0.38-0.85, p = 0.005, I2 = 80%). HFNC was associated with an improvement of PaO2/FiO2 and respiratory rate compared to COT. The use of HFNC compared to COT did not reduce the mortality rate, days free from invasive mechanical ventilation, hospital length of stay, or ICU length of stay.

Compared to COT, HFNC may decrease the need for tracheal intubation in patients with COVID-19-related AHRF, particularly among patients with baseline PaO2/FiO2 < 200 mmHg and those in ICU settings.

This systematic review and meta-analysis protocol was prospectively registered with PROSPERO (no. CRD42022339072).

Critically ill patients with COVID-19 develop acute respiratory distress syndrome characterized by relatively well-preserved pulmonary compliance but severe hypoxemia. The challenge in managing such patients lies in optimizing oxygenation, which can be achieved through either high oxygen flow or noninvasive mechanical ventilation. This study was performed to compare the efficiency of two methods of noninvasive oxygen therapy: continuous positive airway pressure (CPAP) and high-flow nasal oxygen therapy (HFNO).

This retrospective cohort study involved 668 patients hospitalized in the intensive care unit (ICU) of the "Sf. Apostol Andrei" Emergency Clinical Hospital, Galati, Romania from 1 April 2020 to 31 March 2021 (CPAP, n = 108; HFNO, n = 108).

Mortality was significantly lower in the CPAP and HFNO groups than in the group of patients who underwent intubation and mechanical ventilation after ICU admission. Mortality in the ICU was not significantly different between the CPAP and HFNO groups.

HFNO and CPAP represent efficient alternative therapies for patients with severe COVID-19 whose respiratory treatment has failed. Studies involving larger groups of patients are necessary to establish a personalized, more complex management modality for critically ill patients with COVID-19.

High-flow nasal cannula (HFNC) has recently emerged as a crucial therapeutic strategy for hypoxemic patients both in acute and chronic settings. Indeed, HFNC therapy is able to deliver higher fractions of inspired oxygen (FiO2) with a heated and humidified gas flow ranging from 20 up to 60 L per minute, in a more comfortable way for the patient in comparison with Conventional Oxygen Therapy (COT). In fact, the flow keeps the epithelium of the airways adequately moisturized, thus positively affecting the mucus clearance. Finally, the flow is able to wash out the carbon dioxide in the dead space of the airways; this is also enhanced by a modest positive end-expiratory pressure (PEEP) effect. Recent evidence has shown applications of HFNC in exercise training and chronic settings with promising results. In this narrative review, we explored how HFNC might contribute to enhancing outcomes of exercise training and pulmonary rehabilitation among patients dealing with chronic obstructive pulmonary disease, interstitial lung diseases, and lung cancer.

High-flow nasal cannula (HFNC) oxygen therapy is gaining traction globally as a treatment for respiratory failure. There are several physiological benefits, and there is a growing body of evidence showing improved quality of life and patient comfort with HFNC, both in acute and home settings. Due to the increased burden of long-term respiratory conditions such as chronic obstructive pulmonary disease (COPD) on healthcare systems worldwide, the role of ward-based and post-discharge interventions in the prevention of hospital readmissions is an area of increasing interest. In this narrative review, we outline the physiological effects of HFNC and assess its applications in both the hospital and home settings for acute and chronic respiratory failure. We also consider the evidence of non-invasive ventilation (NIV) versus HFNC in the hospital setting and the application of HFNC at home in stable hypercapnic respiratory failure to improve the quality of life and prevent readmissions. We also look at applications of HFNC in specific circumstances, such as the perioperative period, emergency department, and acute (mainly critical care) setting including in immunocompromised patients and palliative care.

High-flow nasal cannula (HFNC) oxygen therapy is essentially a constant-flow, noninvasive respiratory support system similar to a noninvasive ventilator operating in constant-flow mode. The clinical outcome of HFNC oxygen therapy is strongly associated with the pressure generated by high-flow gas and the patient's comfort level. This study was performed to explore the relevant factors affecting pressure and comfort of HFNC oxygen therapy in vivo.

Thirty-five healthy volunteers were enrolled in the trial. They underwent placement of nasal cannulas of various inner diameters (3, 4 or 5 mm) and treatment with different HFNC devices [HFT-300 (Weishengkang Medical Technology Co., Ltd., Jiangsu China) or H-80 M (BMC Medical Co., Ltd., Beijing China)],and the nasal airway pressure and comfort were assessed. Multiple linear regression was used to determine predictors of airway pressure.

Multiple linear regression showed that the end-expiratory pressure was associated with the flow rate, sex, height, and cannula size. The end-expiratory pressure increased by 0.6 cmH2O per 1-mm increase in cannula diameter, decreased by 0.3 cmH2O per 10-cm increase in participant height (with a 0.35 cmH2O decrease for men), and increased by 1 cmH2O when the flow rate increased by 10 L/min (R2 = 0.75, P < 0.05 for all variables in model). In addition, the pressure generated by the H-80 M device was higher than that generated by the HFT-300 device (P < 0.05). Discomfort manifested as difficulty in expiration, and its severity increased as the cannula diameter increased; however there was no significant difference in comfort between the two HFNC devices (P > 0.05).

In volunteers undergoing HFNC oxygen therapy, the nasal cannula diameter, flow rate, sex, height, and device model can affect the nasal airway pressure, and the nasal catheter diameter and flow rate can affect comfort. These factors should be given close attention in clinical practice.

ChiCTR2300068313 (date of first registration: 14 February 2023,  https://www.chictr.org.cn ).

High-flow nasal cannula (HFNC) is widely used to treat hypoxemic respiratory failure. The effectiveness of HFNC treatment and the methods for monitoring its efficacy in the general ward remain unclear. This prospective observational study enrolled 42 patients who had acute hypoxemic respiratory failure requiring HFNC oxygen therapy in the general adult respiratory ward. The primary outcome was the all-cause in-hospital mortality. Secondary outcomes included the association between initial blood test results and HFNC outcomes. Regional ventilation distributions were monitored in 24 patients using electrical impedance tomography (EIT) after HFNC initiation. Patients with successful HFNC treatment had better in-hospital survival (94%) compared to those with failed HFNC treatment (0%, p < 0.001). Neutrophil-to-lymphocyte ratios of ≥9 were more common in patients with failed HFNC (70%) compared to those with successful HFNC (52%, p = 0.070), and these patients had shorter hospital survival rates after HFNC treatment (p = 0.046, Tarone-Ware test). Patients with successful HFNC treatment had a more central ventilation distribution compared to those with failed HFNC treatment (p < 0.05). Similarly, patients who survived HFNC treatment had a more central distribution compared to those who did not survive (p < 0.001). We concluded that HFNC in the general respiratory ward may be a potential rescue therapy for patients with respiratory failure. EIT can potentially monitor patients receiving HFNC therapy.

Primary studies have demonstrated the effectiveness of noninvasive respiratory supports, including noninvasive positive pressure ventilation (NIPPV) and high flow nasal cannula (HFNC), for improving oxygenation and ventilation in patients with interstitial lung diseases (ILDs) and acute respiratory failure (ARF). These studies have not been synthesized and are not included in current practice guidelines. This systematic review with meta-analysis synthesizes studies that compared the effectiveness of NIPPV, HFNC and conventional oxygen therapy (COT) for improving oxygenation and ventilation in ILD patients with ARF.

MEDLINE, EMBASE and the Cochrane Library searches were conducted from inception to August 2023. An additional search of relevant primary literature and review articles was also performed. A random effects model was used to estimate the PF ratio (ratio of arterial oxygen partial pressure to fractional inspired oxygen), PaCO2 (partial pressure of carbon dioxide), mortality, intubation rate and hospital length of stay.

Ten studies were included in the systematic review and meta-analysis. Noninvasive respiratory supports demonstrated a significant improvement in PF ratio compared to conventional oxygen therapy (COT); the mean difference was 55.92 (95% CI [18.85-92.99]; p=0.003). Compared to HFNC, there was a significant increase in PF ratio in NIPPV (mean difference 0.45; 95% CI [0.12-0.79]; p=0.008). There were no mortality and intubation rate benefits when comparing NIPPV and HFNC; the mean difference was 1.1; 95% CI [0.83-1.44]; p=0.51 and 1.86; 95% CI [0.42-8.33]; p=0.42, respectively. In addition, there was a significant decrease in hospital length of stay in HFNC compared to NIPPV (mean difference 9.27; 95% Cl [1.45 - 17.1]; p=0.02).

Noninvasive respiratory supports might be an alternative modality in ILDs with ARF. NIPPV demonstrated a potential to improve the PF ratio compared to HFNC. There was no evidence to support the benefit of NIPPV or HFNC in terms of mortality and intubation rate.

Patients with chronic-obstructive-pulmonary-disease (COPD) undergo bronchoscopy for various reasons, and are at relatively higher risk of complications. This study evaluated the efficacy of non-invasive ventilation (NIV) and high-flow-oxygen-therapy (HFOT) compared with conventional-oxygen-therapy (COT) in patients with COPD undergoing bronchoscopy, to prevent hypoxia.

It was a triple-arm, open-label, randomised controlled trial. Ninety patients with COPD were randomly assigned into three intervention arms in 1:1:1 ratio. The incidence of hypoxia, lowest recorded oxygen saturation measured by plethysmography (SpO2), ECG, patient vitals and comfort levels were assessed.

Mean age of the study population was 61.71±7.5 years. Out of 90 cases enrolled, 51, 34 and 5 were moderate, severe and very-severe COPD, respectively, as per GOLD (Global Initiative for Chronic Obstructive Lung Disease) classification. Rest of the baseline characteristics were similar. SpO2 during flexible bronchoscopy (FB) was lowest in COT group (COT: 87.03±5.7% vs HFOT: 95.57±5.0% vs NIV: 97.40±1.6%, p<0.001). Secondary objectives were similar except respiratory-rate (breaths-per-minute) which was highest in COT group (COT: 20.23±3.1 vs HFOT: 18.57±4.1 vs NIV: 16.80±1.9, p<0.001). Whereas post FB partial of oxygen in arterial blood was highest in NIV group (NIV: 84.27±21.6 mm Hg vs HFOT: 69.03±13.6 mm Hg vs COT: 69.30±11.9 mm Hg, p<0.001). Post FB partial pressure of carbon dioxide in arterial blood was similar in the three arms. Operator's ease-of-performing-procedure was least in the NIV group as assessed with Visual Analogue Scale (p<0.01). A higher number of NIV group participants reported nasal pain as compared with the other two arms (p<0.01).

NIV and HFOT are superior to COT in preventing hypoxia during bronchoscopy, but NIV is associated with poor patient-tolerance and inferior operator's ease of doing procedure.

CTRI/2021/03/032190.

Respiratory management is an important aspect of care in neuroanesthesia practice for neurosurgical patients. A wide variety of procedures are performed under sedation in the neurosurgical population, and maintaining oxygenation is of paramount importance during these procedures. The high-flow oxygen devices improve arterial oxygenation by providing higher inspiratory oxygen concentration and maintaining higher dynamic positive airway pressure. These devices have gained importance during the recent years with regard to enhancing patient safety. This narrative review focuses on the role of trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) and high-flow nasal oxygenation (HFNO) techniques in the neuroanesthesia practice and electroconvulsive therapy.

High-flow nasal cannula oxygen therapy (HFNC) is recommended for patients with COVID-19. However, the increasing use of HFNC brings a risk of delayed intubation. The optimal timing of switching from HFNC to invasive mechanical ventilation (IMV) remains unclear. An effective predictor is needed to assist in deciding on the timing of intubation. Respiratory rate and oxygenation (ROX) index, defined as (SpO2/FiO2) / respiratory rate, has already shown good diagnostic accuracy. Modified ROX (mROX) index, defined as (PaO2 /FiO2) / respiratory rate, might be better than the ROX index in predicting HFNC failure.

The aim was to evaluate the predictive value of mROX for HFNC failure in patients with COVID-19.

Severe or critical patients with COVID-19 treated with HFNC were enrolled in two clinical centers. Laboratory indicators, respiratory parameters, and mROX index at 0 h and 2 h after initial HFNC were collected. Based on the need for IMV after HFNC initiation, the patients were divided into an HFNC failure group and an HFNC success group. The predictive value of mROX index for IMV was evaluated by the area under the receiver operating characteristic curve (AUROC) and logistic regression analysis. We performed Kaplan-Meier survival analysis using the log-rank test.

Sixty patients with COVID-19 (mean ± SD age, 62.8 ± 14.1 years; 42 patients were male) receiving HFNC were evaluated, including 18 critical and 42 severe cases. A total of 33 patients had hypertension; 14 had diabetes; 17 had chronic cardiac disease; 11 had chronic lung disease; 13 had chronic kidney disease; and 17 had a history of stroke. The AUROC of mROX index at 2 h was superior to that of other respiratory parameters to predict the need for IMV (0.959; p < 0.001). At the mROX index cutoff point of 4.45, predicting HFNC failure reached the optimal threshold, with specificity of 94% and sensitivity of 92%. Logistic regression analysis showed that 2-h mROX index < 4.45 was a protective factor for IMV (odd radio 0.18; 95% CI 0.05-0.64; p = 0.008). In the HFNC failure group, the median time from HFNC to IMV was 22.5 h. The 28-day mortality of the late intubation patients (≥ 22.5 h) was higher than that of the early intubation patients (< 22.5 h) (53.8% vs. 8.3%; p = 0.023).

mROX at 2 h is a good early warning index of the need for IMV in patients with COVID-19 after HFNC initiation. Early intubation may lead to better survival in patients with 2-h mROX index < 4.45.

High-flow nasal oxygen (HFNO) is increasingly used in patients with acute hypoxemic respiratory failure. It is uncertain whether a broadened Berlin definition of acute respiratory distress syndrome (ARDS), in which ARDS can be diagnosed in patients who are not receiving ventilation, results in similar groups of patients receiving HFNO as in patients receiving ventilation.

We applied a broadened definition of ARDS in a multicenter, observational study in adult critically ill patients with acute hypoxemic respiratory failure due to coronavirus disease 2019 (COVID-19), wherein the requirement for a minimal level of 5 cm H₂O PEEP with ventilation is replaced by a minimal level of airflow rate with HFNO, and compared baseline characteristics and outcomes between patients receiving HFNO and patients receiving ventilation. The primary endpoint was ICU mortality. We also compared outcomes in risk for death groups using the PaO₂/FiO₂ cutoffs as used successfully in the original definition of ARDS. Secondary endpoints were hospital mortality; mortality on days 28 and 90; need for ventilation within 7 days in patients that started with HFNO; the number of days free from HFNO or ventilation; and ICU and hospital length of stay.

Of 728 included patients, 229 patients started with HFNO and 499 patients with ventilation. All patients fulfilled the broadened Berlin definition of ARDS. Patients receiving HFNO had lower disease severity scores and lower PaO₂/FiO₂ than patients receiving ventilation. ICU mortality was lower in receiving HFNO (22.7 vs 35.6%; p = 0.001). Using PaO₂/FiO₂ cutoffs for mild, moderate and severe arterial hypoxemia created groups with an ICU mortality of 16.7%, 22.0%, and 23.5% (p = 0.906) versus 19.1%, 37.9% and 41.4% (p = 0.002), in patients receiving HFNO versus patients receiving ventilation, respectively.

Using a broadened definition of ARDS may facilitate an earlier diagnosis of ARDS in patients receiving HFNO; however, ARDS patients receiving HFNO and ARDS patients receiving ventilation have distinct baseline characteristics and mortality rates.

The study is registered at ClinicalTrials.gov (identifier NCT04719182).

Mask ventilation during anaesthesia induction is generally used to provide adequate oxygenation but improper mask ventilation can result in gastric insufflation. It has been reported that oxygen administered by transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) during anaesthesia induction can maintain oxygenation but its effect on gastric insufflation is unknown.

The primary aim of this study was to evaluate whether THRIVE provided adequate oxygenation without gastric insufflation. The secondary aim was to explore the change in cross-sectional area of the antrum (CSAa) during anaesthesia induction. Other potential risk factors of gastric insufflation were also explored.

A prospective, randomised, double-blind study.

Single centre, Department of Anaesthesiology, 1 st Affiliated Hospital, Wenzhou Medical University, China, from May 2022 to September 2022.

A total of 210 patients (age >18 years, ASA classification I to III) scheduled to undergo general anaesthesia were enrolled.

For induction of general anaesthesia, patients were randomised into two groups: THRIVE and pressure-controlled facemask ventilation (PCFV). The THRIVE group received high-flow nasal oxygen with no additional ventilation. The PCFV group had pressure-controlled positive pressure ventilation from the anaesthesia machine via a tight fitting facemask. Gastric insufflation was detected using real-time ultrasonography. The CSAa was measured from ultrasonography images obtained before anaesthesia induction and at 0, 1, 2 and 3 min after loss of consciousness.

The incidence of gastric insufflation during the period from loss of consciousness until intubation.

The THRIVE group had a lower incidence of gastric insufflation during anaesthesia induction than the PCFV group (13.0 vs. 35.3%, odds ratio (OR) = 0.27, 95% confidence interval (CI), 0.14 to 0.56, P  < 0.001). Increase in the CSA after anaesthesia induction was significantly correlated with gastric insufflation (OR = 5.35, 95% CI, 2.90 to 9.89, P  < 0.001). Multivariate logistic regression analysis showed that advancing age (OR = 1.04, 95% CI, 1.01 to 1.07), obstructive sleep apnoea syndrome (OR = 2.43, 95% CI, 1.24 to 4.76), higher Mallampati score (OR = 2.66, 95% CI, 1.21 to 5.85) and PCFV (OR = 4.78, 95% CI, 2.06 to 11.06) were important independent risk factors for gastric insufflation.

During anaesthesia induction, the THRIVE technique provided adequate oxygenation with a reduced incidence of gastric insufflation. PCFV, advancing age, obstructive sleep apnoea syndrome and the Mallampati score were found to be independent risk factors for gastric insufflation during anaesthesia induction.

Chinese Clinical Trial Registry ChiCTR200059555.

Noninvasive respiratory support has been increasingly applied in the immediate postoperative period to prevent postoperative pulmonary complications (PPCs). However, the optimal approach remains uncertain. We sought to evaluate the comparative effectiveness of various noninvasive respiratory strategies used in the immediate postoperative period after cardiac surgery.

We conducted a frequentist random-effect network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing the prophylactic use of noninvasive ventilation (NIV), continuous positive airway pressure (CPAP), high flow nasal cannula (HFNC), or postoperative usual care (PUC) in the immediate postoperative period after cardiac surgery. Databases were systematically searched through September 28, 2022. Study selection, data extraction, and quality assessment were performed in duplicate. The primary outcome was the incidence of PPCs.

Sixteen RCTs enrolling 3011 patients were included. Compared with PUC, NIV significantly reduced the incidence of PPCs [relative risk (RR) 0.67, 95% confidence interval (CI): 0.49 to 0.93; absolute risk reduction (ARR) 7.6%, 95% CI: 1.6-11.8%; low certainty] and the incidence of atelectasis (RR 0.65, 95% CI: 0.45 to 0.93; ARR 19.3%, 95% CI: 3.9-30.4%; moderate certainty); however, prophylactic NIV was not associated with a decreased reintubation rate (RR 0.82, 95% CI: 0.29 to 2.34; low certainty) or reduced short-term mortality (RR 0.64, 95% CI: 0.16 to 2.52; very low certainty). As compared to PUC, the preventive use of CPAP (RR 0.85, 95% CI: 0.60 to 1.20; very low certainty) or HFNC (RR 0.74, 95% CI: 0.46 to 1.20; low certainty) had no significant beneficial effect on the incidence of PPCs, despite exhibiting a downward trend. Based on the surface under the cumulative ranking curve, the highest-ranked treatment for reducing the incidence of PPCs was NIV (83.0%), followed by HFNC (62.5%), CPAP (44.3%), and PUC (10.2%).

Current evidence suggest that the prophylactic use of NIV in the immediate postoperative period is probably the most effective noninvasive respiratory approach to prevent PPCs in patients undergoing cardiac surgery. Given the overall low certainty of the evidence, further high-quality research is warranted to better understand the relative benefits of each noninvasive ventilatory support.

PROSPERO, https://www.crd.york.ac.uk/prospero/ , registry number: CRD42022303904.

The physiological effects of HFNC devices are closely related to temperature and humidity. HFNC devices from different manufacturers may have varied performances. It is unclear whether there are differences in the humidification performance of different HFNC devices and the degree of differences.

Four integrated HFNC devices (AIRVO 2, Fisher & Paykel Healthcare, Auckland, New Zealand; TNI softFlow 50, TNI Medical AG, Würzburg, Germany; HUMID-BH, RESPIRACARE, Shenyang, China; OH-70C, Micomme, Hunan, China) and a ventilator with an HFNC module (bellavista 1000, Imtmedical, Buchs, Switzerland) were evaluated using their matching circuits. The dew point temperature was set at 31, 34, and 37°C (set-DP). In MR850, it was set to non-invasive mode (34°C/-3°C) and invasive mode (40°C/-3°C), respectively. At each level of set-DP, the flow was set from 20 L/min up to its maximum set limit at a gradient of 5 L/min or 10 L/min. After stabilization, the dew point temperature, temperature, relative humidity, and flow rate of the delivered gas from the cannulas were recorded.

There were significant differences in actual-DP among these devices at any set-DP (p < 0.001). The actual-DP of OH-70C and TNI softFlow 50 was lower than set-DP, and the difference between the actual-DP and the set-DP of these two devices increased with the increase of set-DP. AIRVO 2, bellavista 1000 (MR850), and HUMID-BH can provide the nominal humidity at 37°C. The actual-DP increased with the increase of set-flow under each set-DP in AIRVO 2, TNI softFlow 50 and bellavista 1000 (MR850), but decreased when the set-flow was greater than 60 L/min. The actual-T of the delivered gas was higher than actual-DP in all devices and was higher than set-DP in AIRVO 2 and HUMID-BH.

Set-flow, set-DP, and types of devices will affect the actual temperature and humidity of the delivered gas. AIRVO 2, bellavista 1000 (MR850), and HUMID-BH can provide the nominal humidity at 37°C and may be more suitable for tracheotomy patients. The flow rate over 60 L/min should be set with caution.

During the COVID-19 pandemic, the use of non-invasive respiratory support (NIRS) became crucial in treating patients with acute hypoxemic respiratory failure. Despite the fear of viral aerosolization, non-invasive respiratory support has gained attention as a way to alleviate ICU overcrowding and reduce the risks associated with intubation. The COVID-19 pandemic has led to an unprecedented increased demand for research, resulting in numerous publications on observational studies, clinical trials, reviews, and meta-analyses in the past three years. This comprehensive narrative overview describes the physiological rationale, pre-COVID-19 evidence, and results of observational studies and randomized control trials regarding the use of high-flow nasal oxygen, non-invasive mechanical ventilation, and continuous positive airway pressure in adult patients with COVID-19 and associated acute hypoxemic respiratory failure. The review also highlights the significance of guidelines and recommendations provided by international societies and the need for further well-designed research to determine the optimal use of NIRS in treating this population.

High-flow nasal cannula (HFNC) has been proven effective in improving patients with acute hypoxemic respiratory failure (AHRF), but a discussion of its use for initial flow settings still need to be provided. We aimed to compare the effectiveness and comfort evaluation of HFNC with different initial flow settings in patients with AHRF.

Studies published by October 10, 2022, were searched exhaustively in PubMed, Embase, Web of Science, Cochrane Library (CENTRAL), and the China National Knowledge Infrastructure (CNKI) database. Network meta-analysis (NMA) was performed with STATA 17.0 and R software (version 4.2.1). A Bayesian framework was applied for this NMA. Comparisons of competing models based on the deviance information criterion (DIC) were used to select the best model for NMA. The primary outcome is the intubation at day 28. Secondary outcomes included short-term and long-term mortality, comfort score, length of ICU or hospital stay, and 24-h PaO₂/FiO₂.

This NMA included 23 randomized controlled trials (RCTs) with 5774 patients. With NIV as the control, the HFNC_high group was significantly associated with lower intubation rates (odds ratio [OR] 0.72 95% credible interval [CrI] 0.56 to 0.93; moderate quality evidence) and short-term mortality (OR 0.81 95% CrI 0.69 to 0.96; moderate quality evidence). Using HFNC_Moderate (Mod) group (mean difference [MD] - 1.98 95% CrI -3.98 to 0.01; very low quality evidence) as a comparator, the HFNC_Low group had a slight advantage in comfort scores but no statistically significant difference. Of all possible interventions, the HFNC_High group had the highest probability of being the best in reducing intubation rates (73.04%), short-term (82.74%) and long-term mortality (67.08%). While surface under the cumulative ranking curve value (SUCRA) indicated that the HFNC_Low group had the highest probability of being the best in terms of comfort scores.

The high initial flow settings (50-60 L/min) performed better in decreasing the occurrence of intubation and mortality, albeit with poor comfort scores. Treatment of HFNC for AHRF patients ought to be initiated from moderate flow rates (30-40 L/min), and individualized flow settings can make HFNC more sensible in clinical practice.