[High-flow nasal oxygen therapy and hypercapnic acute respiratory failure]. / Oxygénothérapie nasale à haut débit et insuffisance respiratoire aiguë hypercapnique.

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.

Case series of dogs with blastomycosis managed with high-flow nasal oxygen therapy (2019-2023): 19 cases.

Objective: To describe the clinical presentation, progression, treatment, and outcome of dogs with blastomycosis treated with high-flow nasal oxygen therapy (HFNOT). Design: Retrospective case review. Setting: University veterinary teaching hospital. Animals: Nineteen client-owned dogs with strongly suspected or confirmed blastomycosis treated with HFNOT. Measurements and main results: The medical records of dogs with strongly suspected or confirmed blastomycosis between October 2019 and May 2023 that received HFNOT were evaluated. Nineteen dogs were included. Nine dogs were started directly on high-flow nasal oxygen therapy. The remaining 10 dogs first received traditional oxygen therapy and were then transitioned to HFNOT 3-142 h later. Of the 19 dogs, 1 survived to discharge from hospital, 12 were euthanized due to progression of disease, and 6 died during the hospitalization period. Conclusions and clinical importance: The prognosis for survival of dogs with severe blastomycosis requiring therapy beyond traditional oxygen methods was poor to grave in this population. This is the first known documented report of HFNOT use in dogs with confirmed or suspected blastomycosis.

Trophic Nutrition in ICU Patients Undergoing High-Flow Oxygen Therapy and/or Noninvasive Mechanical Ventilation: The Nutri-Trophic Study.

Enteral nutrition (EN) therapy in ICU patients requiring oxygen therapy with high-flow nasal cannula (HFNC) and/or noninvasive mechanical ventilation (NIMV) is controversial. A prospective, cohort, observational, and multicenter study was conducted in 10 ICUs in Spain to analyze the 90-day mortality, tolerance, side effects, and infectious complications of trophic EN in patients requiring HFNC therapy and/or NIVM. A total of 149 patients were enrolled. The mean age, severity scores, tracheobronchitis, bacteremia, and antimicrobial therapy were significantly higher in deceased than in living patients (p < 0.05), and the mortality rate was 14.8%. A total of 110 patients received oral trophic feedings, 36 patients received nasogastric tube feedings (NGFs), and 3 received mixed feedings. Trophic EN was discontinued in only ten (14.9%) patients because of feeding-related complications. The variables selected for the multivariate logistic regression on feeding discontinuation were SOFA upon admission (OR per unit = 1.461) and urea (OR per mg/dL = 1.029). There were no significant differences in the development of new infections according to the route of EN administration. Early trophic feeding administered to patients with acute respiratory failure requiring noninvasive ventilation is safe and feasible, and is associated with few dietary and infectious complications in a mortality, setting comparable to similar studies.

Analysis of therapeutic effects on type II respiratory failure and impact on blood gas changes: high-flow nasal oxygen therapy vs. non-invasive positive pressure ventilation.

OBJECTIVE: To evaluate the efficacy of high-flow nasal oxygen therapy (HFNO) vs. non-invasive positive pressure ventilation (NIPPV) in type II respiratory failure, and analyze their impact on blood gas parameters. METHODS: A retrospective analysis of 110 cases of type II respiratory failure treated from April 2021 to March 2023 categorized patients into control (NIPPV, n=50) and observation (HFNO, n=60) groups. Both groups received comprehensive nursing interventions. Treatment outcomes, respiratory and hemodynamic parameters, blood gas parameters, and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were compared before and 48 hours after treatment. Additionally, the complication rates and independent risk factors affecting prognosis were analyzed. RESULTS: The observation group exhibited superior treatment efficacy compared to the control group (P=0.001). Both groups showed significant improvements in APACHE II scores and respiratory, hemodynamic, and blood gas parameters after treatment (P<0.001), with the observation group experiencing more pronounced improvements (P<0.001). The observation group also had a lower incidence of complications than the control group (P=0.013). Logistic regression identified PaCO2 and treatment protocol as independent risk factors affecting adverse outcomes (P<0.05). CONCLUSION: HFNO demonstrates superior therapeutic efficacy in type II respiratory failure, significantly improving blood gas parameters with a high level of safety, supporting its clinical applicability.

Efficiency of continuous positive airway pressure and high-flow nasal oxygen therapy in critically ill patients with COVID-19.

OBJECTIVE: 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). METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

ROX index performance to predict high-flow nasal oxygen outcome in Covid-19 related hypoxemic acute respiratory failure.

BACKGROUND: Given the pathophysiology of hypoxemia in patients with Covid-19 acute respiratory failure (ARF), it seemed necessary to evaluate whether ROX index (ratio SpO2/FiO2 to respiratory rate) could accurately predict intubation or death in these patients initially treated by high-flow nasal oxygenation (HFNO). We aimed, therefore, to assess the accuracy of ROX index to discriminate between HFNO failure (sensitivity) and HFNO success (specificity). METHODS: We designed a multicentre retrospective cohort study including consecutive patients with Covid-19 ARF. In addition to its accuracy, we assessed the usefulness of ROX index to predict HFNO failure (intubation or death) via logistic regression. RESULTS: Among 218 ARF patients screened, 99 were first treated with HFNO, including 49 HFNO failures (46 intubations, 3 deaths before intubation). At HFNO initiation (H0), ROX index sensitivity was 63% (95%CI 48-77%) and specificity 76% (95%CI 62-87%) using Youden's index. With 4.88 as ROX index cut-off at H12, sensitivity was 29% (95%CI 14-48%) and specificity 90% (95%CI 78-97%). Youden's index yielded 8.73 as ROX index cut-off at H12, with 87% sensitivity (95%CI 70-96%) and 45% specificity (95%CI 31-60%). ROX index at H0 was associated with HFNO failure (p = 0.0005) in univariate analysis. Multivariate analysis showed that SAPS II (p = 0.0003) and radiographic extension of pulmonary injuries (p = 0.0263), rather than ROX index, were predictive of HFNO failure. CONCLUSIONS: ROX index cut-off values seem population-specific and the ROX index appears to have a technically acceptable but clinically low capability to discriminate between HFNO failures and successes in Covid-19 ARF patients. In addition, SAPS II and pulmonary injuries at ICU admission appear more useful than ROX index to predict the risk of intubation.

Comparing high-flow nasal oxygen therapy and normobaric oxygen therapy on the treatment of carbon monoxide poisoning.

AIM: We aimed to investigate whether there is a difference in the rate of decrease in carboxyhemoglobin (COHB) values between high-flow nasal oxygen (HFNO) and normobaric oxygen (NBO) therapy. MATERIAL AND METHOD: This retrospective observational study included patients with carbon monoxide poisoning who were treated with HFNO or NBO (control group). All patients were started on NBO therapy with a non-rebreather face mask at a rate of 15 L/min. In the NBO group, NBO treatment was continued until the COHB value fell below 10%. In the HFNO group, as soon as the preparation of the HFNO device was completed, NBO treatment was terminated and HFNO treatment was started and continued until the COHB value fell below 10%. The primary outcome of the study was the difference between HFNO and NBO in terms of COHB half-life rates. RESULTS: A total of 81 patients were included in the study, 44 in the HFNO group and 37 in the NBO group. The median of COHB t1/2 values between HFNO and the NBO treatment groups were 47.3 (IQR: 25-75%: 31.5-65.4) and 46 (IQR: 25-75%: 32.3-56.2), respectively, but this difference was not statistically significant (p = 0.81). CONCLUSION: The results of this study suggest that HFNO treatment does not have a significant advantage over NBO treatment in the carbon monoxide elimination rate within the first 60 min of treatment.

Long-term survival comparison between the first and second waves among 265 critical COVID-19 patients admitted to the ICU: A retrospective cohort study.

BACKGROUD: Management of severe COVID-19 patients admitted to ICU considerably evolved during the first months of the pandemic. It is unclear, however, whether these changes improved long-term survival of these critically ill patients. METHODS: We conducted a retrospective cohort study in adults with COVID-19 pneumonia admitted to a French ICU between February 2020 and January 2021, a timeframe that covered the first two waves of the pandemic. Primary outcome was to compare long-term survival between the first and second waves. Survival predictor were identified using a Cox proportional-hazards model. RESULTS: We included 265 patients in the cohort: 140 (52.8 %) and 125 (47.2 %) belonging to the first and second waves, respectively. Baseline characteristics of the patients were similar between the two waves. During W2, use of early corticotherapy increased (86.4% vs. 17.8 %; p <0.001), as well as high-flow oxygen therapy use (68.5% vs. 37.4 %; p<0.001). Need for invasive mechanical ventilation decreased (49.6% vs. 72.9 %; p <0.001) and ICU length of stay was shorter (11 [6-22] vs 19 [8-32]days; p = 0.008). ICU mortality was 32.8 % without significant difference between waves. Survival analysis revealed that 3 variables were independently associated with a worse long-term prognosis: a higher SAPS II score (1.05 [1.04-1.06]; p<0.001), a higher age (1.05 [1.01-1.08]; p = 0.005) and admission during W2 (2.22 [1.15-4.28]; p = 0.017). DISCUSSION: Despite substantial changes on management of severe COVID-19 patients, we observed a decreased long-term survival among patients admitted during the second wave. We also noted a shorter ICU length of stay.

The use of non-invasive respiratory assistance to facilitate bronchofiberoscopy performance in patients with hypoxemic (type one) respiratory failure - Study protocol.

PURPOSE: Bronchofiberoscopy (FOB) is a procedure routinely performed for: lung cancer, obstruction, interstitial diseases, foreign bodies' removal, airway clearance, and hemoptysis. It causes acute airway narrowing leading to respiratory and cardiovascular stress. Due to increasing number of ill patients with respiratory failure (RF), conventional oxygen therapy (COT) is frequently insufficient to assure accurate oxygenation and prevent RF in patients requiring FOB. In this clinical scenario, patients may be intubated and supported with invasive mechanical ventilation (IMV) with the specific aim of allowing a safe FOB. However, this invasive strategy is associated with an increased risk of IMV-associated complications. MATERIALS AND METHODS: Our study is a planned prospective multicenter three-arm randomized controlled trial (RCT). The target number of 300 patients was calculated based on the intubation risk in RF patients, which is 0.2-2%. The patients will be assigned to each arm based on Horowitz index. In each arm, the patients will be randomly assigned to one out of two dedicated respiratory support methods in each group i.e. COT/high flow nasal cannula (HFNC), HFNC/non-invasive ventilation (NIV) and NIV/IMV. In the manuscript the current state of art in the area of respiratory support is discussed. We have underlined knowledge gaps in medical evidence which we are planning to reveal with our results. RESULTS: The results of our study are clinically crucial, because they address current gaps concerning COT/HFNC/NIV/IMV. CONCLUSION: The expected findings of this study would allow for careful selection of respiratory support method to safely perform FOB in patients with hypoxemic RF.

Prone versus lateral position in acute hypoxemic respiratory failure patients with HFNO therapy: study protocol for a multicentre randomised controlled open-label trial.

BACKGROUND: High-flow nasal oxygen (HFNO) therapy is a leading treatment technique for acute hypoxemic respiratory failure (AHRF), but its treatment failure rate remains high. The awake prone position (APP) has been proven to increase oxygenation and reduce the endotracheal intubation rate in patients with COVID-19-induced AHRF. However, the APP is poorly tolerated in patients, and its performance in improving prognoses is controversial. The lateral position has a similar mechanism and effect to the prone position, but it is more tolerable than the prone position. Therefore, it is worth exploring whether the lateral position is better for awake patients with AHRF. METHODS: This is a protocol for a three-arm parallel-group multicentre randomised controlled open-label exploratory trial. A total of 583 patients from two hospitals in Chongqing, China, will be randomised to take the semi-recumbent position, lateral position, or prone position at a ratio of 1:1:1. Patients are all diagnosed with AHRF secondary to non-COVID-19 pneumonia or lung infection and receiving HFNO therapy. The primary outcome is ventilator-free days in 28 days. The secondary outcomes are the 28-day intubation rate, 28-day all-cause mortality, total position change time, the incidence of adverse events, number of hours using HFNO therapy, length of hospital and intensive care unit (ICU) stay, and others. We will conduct subgroup analyses on the arterial partial pressure of oxygen to the fraction of inspiration oxygen (PaO2/FiO2) ratio (> 200 mmHg or ≤ 200 mmHg), time from admission to intervention implementation (< 24 h or ≥ 24 h), position changing time, and different diagnoses. DISCUSSION: This trial will explore the prognostic effects of the APP with that of the lateral position in awake patients with non-COVID-19AHRF and compare the differences between them. To provide evidence for clinical decision-making and further research on position management. TRIAL REGISTRATION: This trial was registered in the Chinese Clinical Trial Registry. The registration number is ChiCTR2200055822 . Registered on January 20, 2022.

High-Flow Nasal Oxygen for Severe COVID-19 Pneumonia in Greek Patients: A Prospective Observational Study.

INTRODUCTION: High-flow nasal oxygen (HFNO) and prone positioning may improve outcomes of coronavirus disease 2019 (COVID-19) patients treated in the intensive care unit (ICU). The aim of this study was to describe outcomes following the timely application of HFNO and prone positioning in COVID-19 patients treated in a ward setting. METHODS: The study included 89 prospectively recruited subjects at the COVID-19 ward unit of the University Hospital of Heraklion, Greece, between March and December 2020. RESULTS: Seventy-four (83%) of the 89 subjects in the study had severe COVID-19. Of those, 33 (45%) required HFNO treatment and prone positioning and 15 (45%) were transferred to the ICU, with 4 of them being intubated. Severe COVID-19 and HFNO needs were associated with an increased pneumonia severity index (PSI) score on admission and a worse PaO2/FiO2 ratio. In multivariate analysis, PSI was the only independent predictor of subsequent HFNO needs (OR=1.022). Overall intubation and mortality rates were 5.6% and 3.4%, respectively. CONCLUSION: This study shows that for patients with severe COVID-19 hospitalized in medical wards, standard COVID-19 treatment, along with the timely utilization of HFNO and prone positioning, resulted in excellent outcomes with fewer ICU admission rates.

The use of High-Flow Nasal Oxygen Therapy in 4 dogs undergoing bronchoscopy.

Introduction: High-Flow Nasal Oxygen Therapy is a method to deliver warmed, humidified air-oxygen blended at high flow rates to patients through a nasal cannula using a specialized, commercially available machine. This is a well-tolerated, safe and effective method for oxygen delivery to healthy and hypoxemic dogs. Patients undergoing bronchoscopic procedures frequently develop hypoxemia. Human trials have shown a reduction in incidents of hypoxemic events and higher pulse oximeter oxygen saturation during bronchoscopies in patients on High-Flow Nasal Oxygen. Materials and methods: This is a single-centre, prospective case series. All dogs weighing between 5 and 15 kg and undergoing bronchoscopy during the study period (03/07/2022-01/10/2022) were eligible. Results: Twelve patients were eligible for inclusion of which four were enrolled. No clinically significant complications related to the use of High-Flow Nasal Oxygen Therapy were recorded. Two of the patients were re-intubated post bronchoscopy due to clinician preference for recovery. One of the patients had a self-limiting period of severe hypoxemia with a pulse oximeter oxygen saturation of 84% for < 1 min during bronchoalveolar lavage, and whilst undergoing High-Flow Nasal Oxygen administration. Another patient had a self-limiting episode of mild hypoxemia (SpO2 of 94% lasting < 1 min) 5 min after completion of bronchoalveolar lavage. Conclusion: No clinically relevant complications relating to High-Flow Nasal Oxygen Therapy were recorded in this case series, although further studies are required to confirm this conclusion. This initial data suggests that the use of High-Flow Nasal Oxygen therapy during bronchoscopy is feasible and potentially safe, although it may not prevent hypoxemia in these patients. The use of High-Flow Nasal Oxygen Therapy during bronchoscopy in small patients carries multiple potential benefits and further studies to compare its efficacy against other traditional oxygen delivery systems are warranted in this patient population.

Early non-invasive ventilation and high-flow nasal oxygen therapy for preventing endotracheal intubation in hypoxemic blunt chest trauma patients: the OptiTHO randomized trial.

BACKGROUND: The benefit-risk ratio of prophylactic non-invasive ventilation (NIV) and high-flow nasal oxygen therapy (HFNC-O2) during the early stage of blunt chest trauma remains controversial because of limited data. The main objective of this study was to compare the rate of endotracheal intubation between two NIV strategies in high-risk blunt chest trauma patients. METHODS: The OptiTHO trial was a randomized, open-label, multicenter trial over a two-year period. Every adult patients admitted in intensive care unit within 48 h after a high-risk blunt chest trauma (Thoracic Trauma Severity Score ≥ 8), an estimated PaO2/FiO2 ratio < 300 and no evidence of acute respiratory failure were eligible for study enrollment (Clinical Trial Registration: NCT03943914). The primary objective was to compare the rate of endotracheal intubation for delayed respiratory failure between two NIV strategies: i) a prompt association of HFNC-O2 and "early" NIV in every patient for at least 48 h with vs. ii) the standard of care associating COT and "late" NIV, indicated in patients with respiratory deterioration and/or PaO2/FiO2 ratio ≤ 200 mmHg. Secondary outcomes were the occurrence of chest trauma-related complications (pulmonary infection, delayed hemothorax or moderate-to-severe ARDS). RESULTS: Study enrollment was stopped for futility after a 2-year study period and randomization of 141 patients. Overall, 11 patients (7.8%) required endotracheal intubation for delayed respiratory failure. The rate of endotracheal intubation was not significantly lower in patients treated with the experimental strategy (7% [5/71]) when compared to the control group (8.6% [6/70]), with an adjusted OR = 0.72 (95%IC: 0.20-2.43), p = 0.60. The occurrence of pulmonary infection, delayed hemothorax or delayed ARDS was not significantly lower in patients treated by the experimental strategy (adjusted OR = 1.99 [95%IC: 0.73-5.89], p = 0.18, 0.85 [95%IC: 0.33-2.20], p = 0.74 and 2.14 [95%IC: 0.36-20.77], p = 0.41, respectively). CONCLUSION: A prompt association of HFNC-O2 with preventive NIV did not reduce the rate of endotracheal intubation or secondary respiratory complications when compared to COT and late NIV in high-risk blunt chest trauma patients with non-severe hypoxemia and no sign of acute respiratory failure. CLINICAL TRIAL REGISTRATION: NCT03943914, Registered 7 May 2019.

Clinical review of high-flow nasal oxygen therapy in human and veterinary patients.

Oxygen therapy is the first-line treatment for hypoxemic acute respiratory failure. In veterinary medicine this has traditionally been provided via mask, low-flow nasal oxygen cannulas, oxygen cages and invasive positive pressure ventilation. Traditional non-invasive modalities are limited by the maximum flow rate and fraction of inspired oxygen (FiO2) that can be delivered, variability in oxygen delivery and patient compliance. The invasive techniques are able to provide higher FiO2 in a more predictable manner but are limited by sedation/anesthesia requirements, potential complications and cost. High-flow nasal oxygen therapy (HFNOT) represents an alternative to conventional oxygen therapy. This modality delivers heated and humidified medical gas at adjustable flow rates, up to 60 L/min, and FiO2, up to 100%, via nasal cannulas. It has been proposed that HFNOT improves pulmonary mechanics and reduces respiratory fatigue via reduction of anatomical dead space, provision of low-level positive end-expiratory pressure (PEEP), provision of constant FiO2 at rates corresponding to patient requirements and through improved patient tolerance. Investigations into the use of HFNOT in veterinary patients have increased in frequency since its clinical use was first reported in dogs with acute respiratory failure in 2016. Current indications in dogs include acute respiratory failure associated with pulmonary parenchymal disease, upper airway obstruction and carbon monoxide intoxication. The use of HFNOT has also been advocated in certain conditions in cats and foals. HFNOT is also being used with increasing frequency in the treatment of a widening range of conditions in humans. Although there remains conflict regarding its use and efficacy in some patient groups, overall these reports indicate that HFNOT decreases breathing frequency and work of breathing and reduces the need for escalation of respiratory support. In addition, they provide insight into potential future veterinary applications. Complications of HFNOT have been rarely reported in humans and animals. These are usually self-limiting and typically result in lower morbidity and mortality than those associated with invasive ventilation techniques.

Early Awake Prone Position Combined with High-Flow Nasal Oxygen Therapy in Severe COVID-19: A Case Series.

Background: Awake prone positioning has been used for non-intubated patients with COVID-19-related acute hypoxaemic respiratory failure, but the results are contradictory. We aimed to highlight the role of awake prone positioning combined with high-flow nasal oxygen therapy in severe COVID-19 patients infected with the Delta variant of SARS-CoV-2. Methods: From June 12 to December 7, 2021, we successfully performed prone position(PP) combined with high-flow nasal oxygen(HFNO) therapy on two patients infected with the delta variant of SARS-CoV-2. HFNO was prescribed to reach SpO2 ≥ 92%. PP was proposed to patients with PaO2/FiO2(P/F) < 150 mmHg. Arterial blood gas (ABG) and hemodynamic were monitored before and after PP sessions. The target time of PP was more than 12 h per day and could be appropriately shortened according to the patient's tolerance. Relevant clinical data, HFNO parameters, PICCO parameters, P/F ratio and PP duration were obtained from medical records. Results: A total of 23 PP sessions and 6 PP sessions combined with HFNO were performed in case 1 and case 2, respectively. Compared with values before PP, GEDI, ELWI and Qs/Qt decreased significantly (GEDI: 869.50 ± 60.50 ml/m2 vs. 756.86 ± 88.25 ml/m2; ELWI: 13.64 ± 2.82 ml/kg vs. 12.43 ± 2.50 ml/kg; Qs/Qt: 15.32 ± 6.52% vs. 12.24 ± 5.39%; all p < 0.05), Meanwhile, the oxygenation improved significantly (P/F: 184.50 ± 51.92 mmHg vs. 234.21 ± 88.84 mmHg, p < 0.05), The chest CT revealed the lung infiltrates improved significantly after PP. Both cases were discharged to a dedicated COVID-19 ward without requiring intubation. Conclusions: Combining PP with HFNO could be a useful treatment strategy for avoiding intubation in severe COVID-19 patients infected with the Delta variant of SARS-CoV-2 to improve pulmonary vascular involvement, improve oxygenation and avoid intubation, but further studies are needed to validate our approach.

Aerosol delivery in models of pediatric high flow nasal oxygen and mechanical ventilation.

BACKGROUND: Aerosol drug delivery during high flow nasal oxygen (HFNO) and invasive mechanical ventilation (IMV) are key respiratory care strategies available for the treatment of pediatric patients. We aimed to quantify the impact of different HFNO and IMV set-ups on tracheal drug delivery via a vibrating mesh nebuliser (VMN). METHODS: Percent tracheal dose via VMN was quantified during HFNO therapy and IMV in a benchtop model of a 9-month-old infant. Under HFNO, 3 cannula sizes were used at 3 flow rate settings with the VMN placed at the dry side of the humidifier. Under IMV, tracheal dose when VMN was placed at the dry side of the humidifier, 15 cm from the wye and between the wye and endotracheal tube (ETT) was assessed. Salbutamol at 2.5 mg/2.5 ml (1 mg/ml) was used for each test (N = 5). The impact of VMN refill on circuit pressure under HFNO and IMV was also assessed. RESULTS: Tracheal dose was highest during HFNO with the largest cannula size (OPT318) set to the lowest flow rate setting of 2 L/min (liter per minute) (5.80 ± 0.17%). Increasing flow rate reduced tracheal drug delivery for all cannulas. For IMV, VMN on the dry side of the humidifier and between the wye and ETT gave optimal drug delivery (4.49 ± 0.14% vs. 4.43 ± 0.26% respectively). VMN refill did not impact circuit pressure for either HFNO therapy or IMV. CONCLUSIONS: Gas flow rate and cannula size during HFNO and VMN position during IMV has a significant effect on tracheal drug delivery in a pediatric setting.

Computational design and experimental analysis of a novel visor for COVID-19 patients receiving high-flow nasal oxygen therapy.

The Covid-19 global pandemic has reshaped the requirements of healthcare sectors worldwide. Following the exposure risks associated with Covid-19, this paper aims to design, optimise, and validate a wearable medical device that reduces the risk of transmission of contagious droplets from infected patients in a hospital setting. This study specifically focuses on those receiving high-flow nasal oxygen therapy. The design process consisted of optimising the geometry of the visor to ensure that the maximum possible percentage of harmful droplets exhaled by the patient can be successfully captured by a vacuum tube attached to the visor. This has been completed by deriving a number of concept designs and assessing their effectiveness, based on numerical analysis, computational fluid dynamics (CFD) simulations and experimental testing. The CFD results are validated using various experimental methods such as Schlieren imaging, particle measurement testing and laser sheet visualisation. Droplet capturing efficiency of the visor was measured through CFD and validated through experimental particle measurement testing. The results presented a 5% deviation between CFD and experimental results. Also, the modifications based on the validated CFD results improved the visor effectiveness by 47% and 38% for breathing and coughing events, respectively.

The short-term efficacy of high flow nasal oxygen therapy on cardiovascular surgical patients: a randomized crossover trial.

BACKGROUND: Oxygen therapy after extubation in the intensive care unit (ICU) is essential in order to maintain adequate oxygenation, especially in patients who have undertaken cardiovascular surgery. A Venturi mask (VM) has been routinely used as an oxygen therapy in the ICU. Recently, however, the high flow nasal cannula (HFNC) has become available, and this device can deliver up to 60 L/min of humidified oxygen. The aim of this study is to evaluate the short-term efficacy between HFNC and VM in cardiovascular surgical patients. METHODS: Forty patients who underwent cardiovascular surgery were randomized to either protocol A (HFNC followed by VM) or protocol B (VM followed by HFNC). After 60-minutes of use with either device, arterial blood gas analysis was performed, and the PaO2/FiO2 ratio (PFR) was calculated. Simultaneously, physiological data (respiratory rate, heart rate, mean arterial pressure, continuous cardiac index, and mixed venous oxygen saturation) were recorded. During this procedure, FiO2 and gas flow were maintained at a fixed rate. These variables were compared by using the paired t-test, and a p value < 0.05 was considered significant. All data were expressed as mean (standard deviation). RESULTS: Thirty-five patients (17 from protocol A and 18 from protocol B) were enrolled, and 5 patients were excluded from analysis in accordance with the exit criteria. PaO2 was significantly higher in the HFNC group than in the VM group [101.7 (25.9) vs. 91.8 (23.0), mean difference 9.87 (18.5), 95% confidence interval 3.5 to 16.2, p = 0.003]. Moreover, PFR was significantly higher in the HFNC group than in the VM group [265.9 (81.4) vs. 238.7 (68.5), p = 0.002]. Moreover, PaCO2 was significantly lower in the HFNC group than in the VM group [33.8 (3.5) vs. 34.7 (2.9), p = 0.033]. The respiratory rate was significantly lower in the HFNC group than in the VM group [18 (4) vs. 21 (4), p = 0.006], and no significant differences were seen in any of the other parameters. CONCLUSIONS: Compared to VM, HFNC ameliorated oxygenation function and decreased patients' effort in breathing. The hemodynamic state did not differ between HFNC and VM. Therefore, HFNC can be used safely in cardiovascular surgical patients. TRIAL REGISTRATION: This trial was registered with the UMIN Clinical Trials Registry (ID UMIN000016572).

[Efficacy Analysis of High-flow Nasal Oxygen Therapy in Patients 
Accepting Single-port Video-assisted Thoracoscopic Lobectomy].

BACKGROUND: Patients who underwent lobectomy resection are prone to hypoxemia, and the vast majority present with type I respiratory failure. Thus, improvement of hypoxemia is one of the most important factors to facilitate postoperative recovery of patients. In this study, the superiority-inferiority of different oxygen inhalation methods were compared with high-flow nasal oxygen therapy (HFNO), noninvasive mechanical ventilation (NIMV) and nasal oxygen breath (NOB) in patients with hypoxemia after single-port video-assisted thoracoscopic (VATS) lobectomy, and the clinical efficacy of HFNO in these patients was further investigated. METHODS: A total of 180 patients from the Second Affiliated Hospital of Soochow University in China with hypoxemia who accepting single-port VATS lobectomy from June 2021 to March 2022 were randomly divided into three groups (n=60), which were treated with HFNO, NIMV and NOB, respectively. The results of arterial blood gas analysis, patient's comfort score and incidence of complications were observed before, 1 h, 6 h-12 h and after use. Statistical analyses were conducted using statistical program for social sciences 25.0 (SPSS 25.0), and P<0.05 was considered as statistical significance. RESULTS: For patients with hypoxemia after accepting single-port VATS lobectomy, HFNO was no less effective than NIMV (P=0.333), and both of whom could fast increase patients' partial pressure of oxygen/fraction of inspiration O2 (PaO2/FiO2) compared to NOB (P<0.001). Besides, HFNO shows a great advantage in comfort degree and stay length (P<0.001, P=0.004), and incidence of complications were slightly lower than other groups (P=0.232). But it is worthy to note that HFNO is still slightly less effective than NIMV in patients with postoperative hypoxemia accompanied by elevated partial pressure of carbon dioxide (PaCO2). CONCLUSIONS: For patients with hypoxemia who accepting single-port VATS lobectomy, HFNO can be used as the first choice. However, for patients with postoperative hypoxemia accompanied by elevated PaCO2, NIMV is still recommended to improve oxygenation.