Conventional Oxygen Research Articles

High Flow Oxygen Therapy – Risks and Rewards

Introduction High Flow Oxygen Therapy via Nasal Cannula (HFNC) has documented advantages over conventional oxygen therapy (COT). It’s been noted to improve the survival rate among patients with acute hypoxemic respiratory failure, and potentially reduce the incidence of more invasive care. Adjustable oxygen concentration and higher flows that match the inspiratory demand of the patient with respiratory distress result in less entrainment of room air, which dilutes the fraction of inspired oxygen (FiO2) and therefore reduces effectiveness of intended use. Higher flows have been demanded by the clinical community and are associated with a reduction of both PaCO2 and metabolic work. Newer High Flow devices offer higher flow rates up to 80 liters per minute. We examined whether the use of 60 and 80 liters per minute set flows would create an increased risk of gastric insufflation and possibly aspiration. Methods Bench study to compare the pressures generated using different flow rates in two commercially available HFNC devices in three different conditions: Open and closed system (mouth) breathing, breathing against active exhalation, and complete downstream occlusion. Results Our bench study found that high flow rate therapy did not elevate airway pressures to a level that would result in gastric distention and potential aspiration. In the open mouth test, the pressure ranged from minimum 0.2 to maximum of 1.3 cmH2O, and from minimum of 0.52 to 5.27 cmH2O in the closed mouth test. In the active breathing test, the pressures ranged from minimum 1.5 to 6 cmH2O. In the complete occlusion test, the pressures ranged from minimum 0.37 to 4.49 cmH2O. Conclusion Flows provided during HFNC therapy do not pose a hazard of creating high pressures which exceed esophageal opening pressure and pose a risk of gastric distention. The higher flow rates may reduce the risk associated with the potential false positive prediction of HFNC failure when therapy is not set to match the patient’s inspiratory peak flow demand. The benefit of higher flows to match the inspiratory demand provides a rarely recognized additional benefit of improving the accuracy of predictive indices such as the ROX index and allows for high flow therapy to more fully achieve its intended use.

Effect of post-extubation high-flow nasal cannula combined with respiratory training versus conventional oxygen therapy on postoperative pulmonary complications in patients after major abdominal surgery: protocol for a single-centre randomized controlled trial

BackgroundNearly 234 million patients undergo surgery each year, and 1.3 million among them develop complications. Patients undergoing major upper abdominal surgery (operation time > 2 h) have a really high incidence of postoperative pulmonary complications (PPCs). The occurrence of PPCs seriously affects the outcomes of patients. High-flow nasal cannula (HFNC) is as effective as noninvasive ventilation (NIV) in preventing postoperative hypoxaemia and respiratory failure. Respiratory training using positive expiratory pressure (PEP) Acapella (Choice) has been shown to help patients with rapid recovery from postoperative atelectasis. However, no relevant randomized controlled studies have been conducted to clarify the effect of HFNC combined with respiratory training in the prevention of PPCs. This study aims to investigate whether the use of HFNC combined with respiratory training could reduce the incidence of PPCs within 7 days after major upper abdominal surgery compared to that with conventional oxygen therapy (COT).MethodsThis is a randomized controlled single-centre trial. A total of 328 patients who undergo major abdominal surgery will be included. Subjects who fulfil the eligible criteria will be randomly assigned into the combination treatment group (Group A) or COT group (Group B) after extubation. The interventions will begin within 30 min of extubation. Patients in Group A will receive HFNC for at least 48 h and respiratory training three times a day for at least 72 h. Patients in Group B will receive oxygen therapy through a nasal catheter or mask for at least 48 h. Our primary endpoint is the incidence of PPCs within 7 days, and the secondary outcome measures include 28-day mortality, reintubation rate, length of hospital stay, and all-cause mortality within 1 year.DiscussionThis trial would help provide evidence on the effectivity of applying HFNC combined with respiratory training for the prevention of PPCs in patients undergoing major upper abdominal surgery. The objective of this study is to determine the optimal treatment approach to improve the prognosis of patients undergoing surgery.Trial registrationChiCTR2100047146. Registered on 8 June 2021. Retrospectively registered.

Rational design of tungsten-doped cobalt molybdate nanosheet arrays for highly active ethanol-assisted hydrogen production

Ethanol oxidation reaction (EOR) is a promising substituent to the conventional oxygen evolution reaction (OER) for highly active and energy-saving hydrogen production. The rational design of bifunctional electrocatalysts to achieve ethanol-assisted water splitting is important, but still maintains challenge. Herein, we successfully synthesize a tungsten (W) doped cobalt molybdate nanosheet arrays on porous copper foam by one-step hydrothermal method (W–CoMoO4/CF). The synthesized W–CoMoO4/CF shows the morphology of neatly stacked cobblestone nanosheets with high surface area and improved reaction kinetics, leading to substantial bifunctional catalytic activity for EOR/hydrogen evolution reactions (HER). To reach a current density of 100 mA cm−2, only an overpotential of 102 mV is demanded when using W–CoMoO4/CF as an electrode for HER, while a potential of 1.40 V is required for EOR. Moreover, the ethanol-assisted water electrolyzer is constructed by using W–CoMoO4/CF as both anode/cathode, which requires a small total voltage of 1.54 V to achieve 100 mA cm−2 and could run steadily for 12 h, revealing its excellent application prospects. This study provides a promising guidance for the development of high-valence metal modified bimetallic oxides for hydrogen generation.

Association of Extubation Failure Rates With High-Flow Nasal Cannula, Continuous Positive Airway Pressure, and Bilevel Positive Airway Pressure vs Conventional Oxygen Therapy in Infants and Young Children

Extubation failure (EF) has been associated with worse outcomes in critically ill children. The relative efficacy of different modes of noninvasive respiratory support (NRS) to prevent EF is unknown. To study the reported relative efficacy of different modes of NRS (high-flow nasal cannula [HFNC], continuous positive airway pressure [CPAP], and bilevel positive airway pressure [BiPAP]) compared to conventional oxygen therapy (COT). MEDLINE, Embase, and CINAHL Complete through May 2022. Randomized clinical trials that enrolled critically ill children receiving invasive mechanical ventilation for more than 24 hours and compared the efficacy of different modes of postextubation NRS. Random-effects models were fit using a bayesian network meta-analysis framework. Between-group comparisons were estimated using odds ratios (ORs) or mean differences with 95% credible intervals (CrIs). Treatment rankings were assessed by rank probabilities and the surface under the cumulative rank curve (SUCRA). The primary outcome was EF (reintubation within 48 to 72 hours). Secondary outcomes were treatment failure (TF, reintubation plus NRS escalation or crossover to another NRS mode), pediatric intensive care unit (PICU) mortality, PICU and hospital length of stay, abdominal distension, and nasal injury. A total of 11 615 citations were screened, and 9 randomized clinical trials with a total of 1421 participants were included. Both CPAP and HFNC were found to be more effective than COT in reducing EF and TF (CPAP: OR for EF, 0.43; 95% CrI, 0.17-1.0 and OR for TF 0.27, 95% CrI 0.11-0.57 and HFNC: OR for EF, 0.64; 95% CrI, 0.24-1.0 and OR for TF, 0.34; 95% CrI, 0.16- 0.65). CPAP had the highest likelihood of being the best intervention for both EF (SUCRA, 0.83) and TF (SUCRA, 0.91). Although not statistically significant, BiPAP was likely to be better than COT for preventing both EF and TF. Compared to COT, CPAP and BiPAP were reported as showing a modest increase (approximately 3%) in nasal injury and abdominal distension. The studies included in this systematic review and network meta-analysis found that compared with COT, EF and TF rates were lower with modest increases in abdominal distension and nasal injury. Of the modes evaluated, CPAP was associated with the lowest rates of EF and TF.

Effects of high flow nasal cannula following minimally invasive esophagectomy in ICU patients: A prospective pre-post study

Patients with esophageal cancer who undergo minimally invasive esophagectomy are at risk of postoperative pulmonary complications. High-flow nasal cannula oxygen therapy delivers humidified, warmed positive airway pressure but has not been applied routinely after surgery. Here, we aimed to compare high-flow nasal cannula and conventional oxygen therapy in patients with esophageal cancer during intensive care unit hospitalization 48h postoperatively. In this prospective pre- and post-intervention study, patients with esophageal cancer who underwent elective minimally invasive esophagectomy (MIE) and were extubated in the operation room and admitted to the intensive care unit postoperatively were assigned to receive either high-flow nasal cannula (HFNCO) or standard oxygen (SO) therapy. Participants in the SO group were recruited before January 2020, and those in the HFNCO group were enrolled after January 2020. The primary outcome was the difference in postoperative pulmonary complication incidence. Secondary outcomes were the occurrence of desaturation within 48h, PaO2/FiO2 within 48h, anastomotic leakage, length of intensive care unit and hospital stay, and mortality. The standard oxygen and high-flow nasal cannula oxygen groups comprised 33 and 36 patients, respectively. Baseline characteristics were comparable between groups. In the HFNCO group, postoperative pulmonary complication incidence was significantly reduced (22.2% vs 45.5%) and PaO2/FiO2 was significantly increased. No other between-group differences were observed. HFNCO therapy significantly reduced postoperative pulmonary complication incidence after elective MIE in patients with esophageal cancer without increasing the risk of anastomotic leakage.

EE299 Cost Analysis of High-Flow Oxygen Therapy Compared with Conventional Oxygen Therapy in Severe COVID-19 in Colombia: Data from a Randomized Clinical Trial

EE299 Cost Analysis of High-Flow Oxygen Therapy Compared with Conventional Oxygen Therapy in Severe COVID-19 in Colombia: Data from a Randomized Clinical Trial

Barotrauma during Noninvasive Respiratory Support in COVID-19 Pneumonia Outside ICU: The Ancillary COVIMIX-2 Study.

Noninvasive respiratory support (NIRS) has been extensively used during the COVID-19 surge for patients with acute respiratory failure. However, little data are available about barotrauma during NIRS in patients treated outside the intensive care unit (ICU) setting. COVIMIX-2 was an ancillary analysis of the previous COVIMIX study, a large multicenter observational work investigating the frequencies of barotrauma (i.e., pneumothorax and pneumomediastinum) in adult patients with COVID-19 interstitial pneumonia. Only patients treated with NIRS outside the ICU were considered. Baseline characteristics, clinical and radiological disease severity, type of ventilatory support used, blood tests and mortality were recorded. In all, 179 patients were included, 60 of them with barotrauma. They were older and had lower BMI than controls (p < 0.001 and p = 0.045, respectively). Cases had higher respiratory rates and lower PaO2/FiO2 (p = 0.009 and p < 0.001). The frequency of barotrauma was 0.3% [0.1-1.3%], with older age being a risk factor for barotrauma (OR 1.06, p = 0.015). Alveolar-arterial gradient (A-a) DO2 was protective against barotrauma (OR 0.92 [0.87-0.99], p = 0.026). Barotrauma required active treatment, with drainage, in only a minority of cases. The type of NIRS was not explicitly related to the development of barotrauma. Still, an escalation of respiratory support from conventional oxygen therapy, high flow nasal cannula to noninvasive respiratory mask was predictive for in-hospital death (OR 15.51, p = 0.001). COVIMIX-2 showed a low frequency for barotrauma, around 0.3%. The type of NIRS used seems not to increase this risk. Patients with barotrauma were older, with more severe systemic disease, and showed increased mortality.

Factors associated with intubation in patients with acute hypoxaemic respiratory failure treated with high-flow nasal cannula oxygen therapy: A prospective, observational study

BackgroundHigh-flow nasal cannula (HFNC) oxygen is an alternative to conventional oxygen in acute hypoxaemic respiratory failure. Some patients require intubation, with a risk of delay; thus, early predictors may identify those requiring earlier intubation. The “ROX” index (ratio of pulse oximetry/fraction of inspired oxygen to respiratory rate) predicts intubation in patients with pneumonia treated with HFNC therapy, but this index has not been validated in non-pneumonia causes of acute hypoxaemic respiratory failure. Aim/ObjectiveThe aim of this study was to identify factors associated with intubation in a heterogeneous group of patients with acute hypoxaemic respiratory failure treated with HFNC oxygen. MethodsThis prospective observational study was undertaken in an Australian tertiary intensive care unit and included patients over 18 y of age with acute hypoxaemic respiratory failure who were treated with oxygen via HFNC. Vital signs and arterial blood gases were recorded prospectively at baseline and regular prespecified intervals for 48 h after HFNC initiation. Multivariate logistic regression was used to identify the factors associated with intubation. ResultsForty-three patients were included (N = 43). The multivariate factors associated with intubation were admission Sequential Organ Failure Assessment score (odds ratio [OR]: 1.94 [95% confidence interval {CI}: 1.06–3.57]; p = 0.032) and Pneumonia Severity Index (OR: 0.95 [95% CI: 0.90–0.99]; p = 0.034). The ROX index was not independently associated with intubation when adjusted for Sequential Organ Failure Assessment score (OR: 0.71 [95% CI: 0.47–1.06]; p = 0.09). There was no difference in mortality between patients intubated early (<24 h) compared to those intubated late. ConclusionsIntubation was associated with admission Sequential Organ Failure Assessment score and Pneumonia Severity Index. The ROX index was not associated with intubation when adjusted for admission Sequential Organ Failure Assessment score. Outcomes were similar irrespective of whether patients were intubated late rather than early.

Noninvasive ventilation in patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis of randomized controlled trials

The clinical benefits of noninvasive ventilation (NIV) for patients with acute hypoxemic respiratory failure (AHRF) is still inconclusive. We aimed to evaluate the effect of NIV compared with conventional oxygen therapy (COT)/high-flow nasal cannula (HFNC) in this patient population. We searched for relevant studies from PubMed, Embase, Cochrane Library, ClinicalTrials.gov, CINHAL, Web of Science up to August 2019 for randomized controlled trials (RCTs) that compared NIV with COT/HFNC in AHRF. The primary outcome was the tracheal intubation rate. Secondary outcomes were intensive care unit (ICU) mortality, and hospital mortality. We applied the GRADE approach to grade the strength of the evidence. Seventeen RCTs that recruited 1738 patients were included in our meta-analysis. When comparing NIV versus COT/HFNC, the pooled risk ratio (RR) for the tracheal intubation rate was 0.68, 95% confidence interval (CI) 0.52–0.89, p = 0.005, I2 = 72.4%, low certainty of evidence. There were no significant differences in ICU mortality (pooled RR = 0.87, 95% CI 0.60–1.26), p = 0.45, I2 = 64.6%) and hospital mortality (pooled RR = 0.71, 95% CI 0.51–1.00, p = 0.05, I2 = 27.4%). Subgroup analysis revealed that NIV application with helmet was significantly associated with a lower intubation rate than NIV with face mask. NIV did not show a significant reduction in intubation rate compared to HFNC. In conclusion, NIV application in patients with medical illness and AHRF was associated with a lower risk of tracheal intubation compared to COT. NIV with helmet and HFNC are promising strategies to avoid tracheal intubation in this patient population and warrant further studies. NIV application had no effect on mortality.The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42018087342).

Association of Non-Invasive Respiratory Support with Extubation Outcomes in Brain-Injured Patients Receiving Mechanical Ventilation: A Secondary Analysis of ENIO.

Non-invasive respiratory support using high flow nasal cannula (HFNC) or non-invasive positive pressure ventilation (NIPPV) can decrease the risk of reintubation in patients being liberated from mechanical ventilation, but effects in patients with acute brain injury are unknown. To evaluate the association between post-extubation non-invasive respiratory support and reintubation in patients with acute brain injury being liberated from mechanical ventilation. This was a secondary analysis of a prospective, observational study of mechanically ventilated patients with acute brain injury (NCT03400904). The primary endpoint was reintubation during ICU admission. We used mixed effects logistic regression models with patient-level covariates and random intercepts for hospital and country to evaluate the association between prophylactic (i.e, planned) HFNC or NIPPV and reintubation. 1,115 patients were included from 62 hospitals and 19 countries, of whom 267 received HFNC or NIPPV following extubation (23.9%). Compared to conventional oxygen therapy, neither prophylactic HFNC nor NIPPV was associated with decreased risk of reintubation (respectively, odds ratio (OR), 0.97; 95% confidence interval (CI), 0.54-1.73; OR, 0.63; 95%CI, 0.30-1.32). Findings remained consistent in sensitivity analyses accounting for alternate adjustment procedures, missing data, shorter timeframes of extubation failure, and competing risks precluding reintubation. In a Bayesian analysis using skeptical and data-driven priors, the probability of reduced reintubation ranged from 17-34% for HFNC and 46-74% for NIPPV. In a large cohort of brain-injured patients undergoing liberation from mechanical ventilation, prophylactic use of HFNC and NIPPV were not associated with reintubation. Prospective trials are needed to explore treatment effects in this population.

The Effect of High Flow Nasal Oxygen Cannula Versus Conventional Oxygen Therapy in COPD Patients with Indication for Long-term Oxygen Therapy: A Pilot Randomized Crossover Study

Background: Long-term oxygen therapy (LTOT) is recommended to be used in stable chronic obstructive pulmonary disease (COPD) patients with severe resting hypoxemia. High-flow nasal oxygen cannula (HFNC) demonstrated benefits in acute hypoxemic respiratory failure. The mechanisms of HFNC by washing out dead space and decreasing work of breathing may be also beneficial in COPD patient who has an indication for LTOT. Objective: To compare the effect of HFNC versus conventional oxygen therapy (COT) in terms of respiratory rate, gas exchange, and health-related quality of life. Materials and Methods: A pilot randomized crossover study was conducted in eleven stable COPD patients. Subjects were randomly assigned to HFNC at a flow rate of 30 L/minute or simple nasal cannula at 2 to 4 L/minute for two weeks in a cross-over fashion. The primary outcome was respiratory rate. The secondary outcomes included blood pressure, heart rate, oxygen saturation (SpO₂), transcutaneous carbon dioxide pressure (PtcCO₂), and St.George’s Respiratory Questionnaire (SGRQ) score. Results: The duration of HFNC and COT use was 8 (IQR 3 to 13) and 14 (IQR 10 to 20) hours/day, respectively (p=0.039). Respiratory rate was significantly lower with HFNC compared to COT at 18 breaths/minute (IQR 16 to 20) versus 22 breaths/minute (IQR 20 to 25) , respectively (p=0.018). SpO₂ was significantly higher with HFNC compared to COT (p=0.046). No differences in blood pressure, heart rate, PtcCO₂, and SGRQ score were observed between the two groups. No serious adverse event from HFNC was observed. Conclusion: The present pilot study demonstrated that HFNC was tolerable in patients with stable COPD who had an indication for LTOT. Respiratory rate was significantly lower and SpO₂ was significantly higher with HFNC compared to COT. Another study with larger sample size is needed to further clarify the efficacy of HFNC in stable COPD patients. Keywords: Chronic obstructive pulmonary disease; Dyspnea; High-flow nasal cannula; Oxygen therapy; Respiratory rate

Risk of air and surface contamination during application of different noninvasive respiratory support for patients with COVID-19

ObjectivesWe compared the risk of environmental contamination among patients with COVID-19 who received high-flow nasal cannula (HFNC), noninvasive ventilation (NIV), and conventional oxygen therapy (COT) via nasal cannula for respiratory failure. MethodsAir was sampled from the hospital isolation rooms with 12 air changes/hr where 26 patients with COVID-19 received HFNC (up to 60 l/min, n = 6), NIV (n = 6), or COT (up to 5 l/min of oxygen, n = 14). Surface samples were collected from 16 patients during air sampling. ResultsViral RNA was detected at comparable frequency in air samples collected from patients receiving HFNC (3/54, 5.6%), NIV (1/54, 1.9%), and COT (4/117, 3.4%) (P = 0.579). Similarly, the risk of surface contamination was comparable among patients receiving HFNC (3/46, 6.5%), NIV (14/72, 19.4%), and COT (8/59, 13.6%) (P = 0.143). An increment in the cyclic thresholds of the upper respiratory specimen prior to air sampling was associated with a reduced SARS-CoV-2 detection risk in air (odds ratio 0.83 [95% confidence interval 0.69-0.96], P = 0.027) by univariate logistic regression. ConclusionNo increased risk of environmental contamination in the isolation rooms was observed in the use of HFNC and NIV vs COT among patients with COVID-19 with respiratory failure. Higher viral load in the respiratory samples was associated with positive air samples.

Paired electrochemical synthesis of formate via oxidation of glycerol and reduction of CO2 in a flow cell reactor

The conventional anodic oxygen evolution (OER) in electrochemical CO2 reduction (CO2R) needs to be replaced as it accounts for a major share in energy consumption while being a product of little to no value. In this work, we replace OER by glycerol oxidation reaction (GOR) to synthesize products such as formate, lactate and glycolate. Hereby, for the first time, GOR was successfully paired with cathodic CO2R to formate in a flow reactor at a significant current density of 50 mA/cm2 producing value added anode products with a simultaneously reduced cell voltage. Using a porous platinum anode, GOR reduced the anode potential as well as cell potential by ∼1 V compared to OER. We report an anodic Faraday efficiency (FE) of 30% to ∼53% for liquid products, of which lactate dominates. The structure of the electrode has a significant impact on the dominant product as mainly formate is synthesized on a planar electrode, where the cummulated FE for all liquid products is up to 76%. The concurrent FE to formate at cathode and anode reached a values of up to 74% and 30% respectively and 66% and 76%, respectively, considering all value-added products. By successfully pairing GOR with CO2R in a flow cell reactor, this work marks an important step towards energy-efficient and economically viable processes.

Effect of early post-extubation high-flow nasal cannula versus conventional low-flow oxygen therapy on reintubation in postoperative patients from prolonged general anesthesia at surgical ICU: A randomized clinical trial (Protocol)

Background: The main concerns following general anesthesia, especially if it lasts longer than 4 hours, are postoperative pulmonary complications, including hypoxemia, lung atelectasis, and acute respiratory failure requiring reintubation. To avoid these complications, postoperative extubation with respiratory support is crucial. The high-flow nasal cannula (HFNC) increases end-expiratory lung volume and reduces the work of breathing to improve oxygenation by delivering a flow-dependent positive airway pressure. The advantages of using HFNC to prevent reintubation have been demonstrated in patients undergoing cardiothoracic surgery. Our target population's information is still deficient, and our trial is set up to uncover this proof. Objectives: To evaluate the effect of high-flow nasal cannula (HFNC) versus low-flow nasal cannula on the reintubation rate and clinical outcomes in the early post-extubation adult who has prolonged general anesthesia for non-cardiothoracic and non-neuro surgery that requires surgical ICU admission. Methods: In this study, 260 patients with an intermediate to high risk of postoperative pulmonary complications following non-cardiothoracic surgery and non-neurosurgery that required general anesthesia for longer than 4 hours were randomly assigned to receive either a high-flow nasal cannula (HFNC) or a low-flow nasal cannula after extubation. The primary outcome indicator is the reintubation rate within 72 hours of tracheal extubation. Postoperative pulmonary complications, the length of stay in the ICU and hospital, and mortality are considered secondary outcome measures. Conclusions: This study is an investigator-initiated randomized controlled trial powered to test the hypothesis that early application of a high-flow nasal cannula probably reduces the reintubation rate in patients in SICUs with prolonged durations of general anesthesia.

Conservative versus conventional oxygen therapy in type I acute respiratory failure patients in respiratory intensive care unit, Zagazig University.

The present study aimed to assess the effect of a conservative (permissive hypoxemia) versus conventional (normoxia) protocol for oxygen supplementation on the outcome of type I respiratory failure patients admitted to respiratory intensive care unit (ICU). This randomized controlled clinical trial was carried out at the Respiratory ICU, Chest Department of Zagazig University Hospital, for 18 months, starting in July 2018. On admission, 56 enrolled patients with acute respiratory failure were randomized in a 1:1 ratio into the conventional group [oxygen therapy was supplied to maintain oxygen saturation (SpO2) between 94% and 97%] and the conservative group (oxygen therapy was administered to maintain SpO2 values between 88% and 92%). Different outcomes were assessed, including ICU mortality, the need for mechanical ventilation (MV) (invasive or non-invasive), and ICU length of stay. In the current study, the partial pressure of oxygen was significantly higher among the conventional group at all times after the baseline reading, and bicarbonate was significantly higher among the conventional group at the first two readings. There was no significant difference in serum lactate level in follow-up readings. The mean duration of MV and ICU length of stay was 6.17±2.05 and 9.25±2.22 days in the conventional group versus 6.46±2.0 and 9.53±2.16 days in the conservative group, respectively, without significant differences between both groups. About 21.4% of conventional group patients died, while 35.7% of conservative group patients died without a significant difference between both groups. We concluded that conservative oxygen therapy may be applied safely to patients with type I acute respiratory failure.

Comparison of High Flow Nasal Therapy with Non-Invasive Ventilation and Conventional Oxygen Therapy for Acute Hypercapnic Respiratory Failure: A Meta-Analysis of Randomized Controlled Trials.

We aimed to evaluate whether high flow nasal cannula (HFNC) is an effective and safe method for adult patients with acute hypercapnic respiratory failure (AHRF). We searched the Cochrane Library, Embase, and PubMed databases from inception to August 2022 to obtain randomized controlled trials (RCTs) that compared HFNC with conventional oxygen treatment (COT) or non-invasive ventilation (NIV) in patients with AHRF, and then performed a meta-analysis. A total of ten parallel RCTs with 1265 individuals were identified. Of them, two studies compared HFNC with COT and eight studies compared HFNC with NIV. In terms of intubation rate, mortality, and arterial blood gas (ABG) improvement, HFNC showed comparable effects to NIV and COT. However, HFNC was more comfortable (mean difference [MD] -1.87, 95% confidence interval [CI] =-2.59, -1.15, P <0.00001, I2 =0%) and resulted in fewer adverse events (odds ratio [OR] 0.12, 95% CI=0.06, 0.28, P<0.00001, I2 = 0%), compared with NIV. In comparison to NIV, HFNC could significantly lower heart rate (HR) (MD -4.66, 95% CI=-6.82, -2.50, P <0.0001, I2 =0%), respiratory rate (RR) (MD -1.17, 95% CI=-2.03, -0.31, P =0.008, I2 =0%), and hospital stay length (MD -0.80, 95% CI=-1.44, -0.16, P =0.01, I2 =0%). NIV showed a decreased frequency in the treatment crossover rate, compared with HFNC in patients with pH<7.30 (OR 5.78, 95% CI=1.50, 22.31, P = 0.01, I2: not applicable). Contrary to COT, HFNC could considerably reduce the need for NIV (OR 0.57, 95% CI=0.35, 0.91, P=0.02, I2=0%). HFNC was effective and safe in patients with AHRF. However, in patients with pH <7.30, HFNC may result in a higher incidence of treatment crossover, compared with NIV. Compared to COT, HFNC may decrease the need for NIV in patients with compensated hypercapnia.

Comparison of High-Flow Nasal Cannula with Conventional Oxygen Therapy in Patients with Hypercapnic Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis.

This study aimed to evaluate the clinical outcomes of high-flow nasal cannula (HFNC) compared with conventional oxygen therapy (COT) in patients with hypercapnic chronic obstructive pulmonary disease (COPD), including arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of oxygen (PaO2), respiratory rate (RR), treatment failure, exacerbation rates, adverse events and comfort evaluation. PubMed, EMBASE and the Cochrane Library were retrieved from inception to September 30, 2022. Eligible trials were randomized controlled trials and crossover studies comparing HFNC and COT in hypercapnic COPD patients. Continuous variables were reported as mean and standard derivation and calculated by weighted mean differences (MD), while dichotomous variables were shown as frequency and proportion and calculated by odds ratio (OR), with the 95% confidence intervals (Cl). Statistical analysis was performed using RevMan 5.4 software. Eight studies were included, five with acute hypercapnia and three with chronic hypercapnia. In acute hypercapnic COPD, short-term HFNC reduced PaCO2 (MD -1.55, 95% CI: -2.85 to -0.25, I² = 0%, p <0.05) and treatment failure (OR 0.54, 95% CI: 0.33 to 0.88, I² = 0%, p<0.05), but there were no significant differences in PaO2 (MD -0.36, 95% CI: -2.23 to 1.52, I² = 45%, p=0.71) and RR (MD -1.07, 95% CI: -2.44 to 0.29, I² = 72%, p=0.12). In chronic hypercapnic COPD, HFNC may reduce COPD exacerbation rates, but there was no advantage in improving PaCO2 (MD -1.21, 95% CI: -3.81 to 1.39, I² = 0%, p=0.36) and PaO2 (MD 2.81, 95% CI: -1.39 to 7.02, I² = 0%, p=0.19). Compared with COT, short-term HFNC reduced PaCO2 and the need for escalating respiratory support in acute hypercapnic COPD, whereas long-term HFNC reduced COPD exacerbations rates in chronic hypercapnia. HFNC has great potential for treating hypercapnic COPD.

Association of Monocyte Distribution Width with the Need for Respiratory Support in Hospitalized COVID-19 Patients.

The monocyte distribution width (MDW), a novel inflammatory biomarker reflecting morphological changes in response to inflammation, has been shown to be useful in identifying COVID-19 infection or predicting death. However, data on the association with predicting the need for respiratory support are still limited. The aim of this study was to determine the association of MDW with the need for respiratory support in patients with SARS-CoV-2 infection. This is a single-center retrospective cohort study. Consecutive hospitalized COVID-19 adult patients who presented at the outpatient department (OPD) or emergency department (ED) between May and August 2021 were enrolled. Respiratory support was defined as any one of the following: conventional oxygen therapy, high-flow oxygen nasal cannula, noninvasive, or invasive mechanical ventilation. The performance of MDW was measured using the area under the receiver operating characteristic (AuROC) curve. Of the 250 enrolled patients, 122 (48.8%) patients received respiratory support. The mean MDW was significantly higher in the respiratory support group: 27.2 ± 4.6 vs 23.6 ± 4.1 (p < 0.001). The MDW ≥ 25 had the best AuROC characteristics of 0.70 (95% CI: 0.65-0.76). The MDW is a potential biomarker that may aid in identifying individuals at risk of requiring oxygen support in COVID-19 and can be easily implemented in clinical practice. Daorattanachai K, Hirunrut C, Pirompanich P, Weschawalit S, Srivilaithon W. Association of Monocyte Distribution Width with the Need for Respiratory Support in Hospitalized COVID-19 Patients. Indian J Crit Care Med 2023;27(5):352-357.

Multistep Dissolution of Lamellar Crystals Generates Superthin Amorphous Ni(OH)2 Catalyst for UOR.

Urea oxidation reaction (UOR) is an ideal replacement of the conventional anodic oxygen evolution reaction (OER) for efficient hydrogen production due to the favorable thermodynamics. However, the UOR activity is severely limited by the high oxidation potential of Ni-based catalysts to form Ni3+ , which is considered as the active site for UOR. Herein, by using in-situ cryoTEM, cryo-electron tomography, and in-situ Raman, combined with theoretical calculations, we report a multistep dissolution process of nickel molybdate hydrate, whereby NiMoO4 ·xH2 O nanosheets exfoliate from the bulk NiMoO4 ·H2 O nanorods due to the dissolution of Mo species and crystalline water, and further dissolution results in superthin and amorphous nickel (II) hydroxide (ANH) flocculus catalyst. Owing to the superthin and amorphous structure, the ANH catalyst can be oxidized to NiOOH at a much lower potential than conventional Ni(OH)2 and finally exhibits more than an order of magnitude higher current density (640mA cm-2 ), 30 times higher mass activity, 27 times higher TOF than those of Ni(OH)2 catalyst. The multistep dissolution mechanism provides an effective methodology for the preparation of highly active amorphous catalysts. This article is protected by copyright. All rights reserved.

Recent trends in the nanozeolites-based oxygen concentrators and their application in respiratory disorders.

Medical-grade oxygen is the basic need for all medical complications, especially in respiratory-based discomforts. There was a drastic increase in the demand for medical-grade oxygen during the current pandemic. The non-availability of medical-grade oxygen led to several complications, including death. The oxygen concentrator was only the last hope for the patient during COVID-19 pandemic around the globe. The demands also are everlasting during other microbial respiratory infections. The yield of oxygen using conventional molecular zeolites in the traditional oxygen concentrator process is less than the yield noticed when its nano-form is used. Nanotechnology has enlightened hope for the efficient production of oxygen by such oxygen concentrators. Here in the current review work, the authors have highlighted the basic structural features of oxygen concentrators along with the current working principle. Besides, it has been tried to bridge the gap between conventional oxygen concentrators and advanced ones by using nanotechnology. Nanoparticles being usually within 100 nm in size have a high surface area to volume ratio, which makes them suitable adsorbents for oxygen. Here authors have suggested the use of nano zeolite in place of molecular zeolites in the oxygen concentrator for efficient delivery of oxygen by the oxygen concentrators.