Comparing nasopharyngeal apnoeic oxygenation at 18 l/min to preoxygenation alone in obese patients - A randomised controlled study.

STUDY OBJECTIVE: Investigate a low-cost, nasopharyngeal apnoeic oxygenation technique, establish its efficacy, and compare it to preoxygenation only in an obese population. The study's hypothesis was that nasopharyngeal apnoeic oxygenation at 18 l.min-1 would significantly prolong safe apnoea time compared to preoxygenation alone. DESIGN: Randomised controlled study. SETTING: Theatre complex of a resource constrained hospital. PATIENTS: 30 adult, obese (BMI ≥ 35 kg.m-2) patients presenting for elective surgery. Patients with limiting cardio-respiratory disease, suspected difficult airway, risk of aspiration, and that were pregnant, were excluded. Patients were allocated by block randomisation in a 1:2 ratio to a preoxygenation-only (No-AO) and an intervention group (NPA-O2). INTERVENTIONS: All patients were preoxygenated to an Et-O2 > 80%, followed by a standardised induction. The intervention group received oxygen at 18 l.min-1 via the nasopharyngeal catheter intervention. The desaturation process was documented until an SpO2 of 92% or 600 s was reached. MEASUREMENTS: Baseline demographic and clinical characteristics were collected. The primary outcome was safe apnoea time, defined as the time taken to desaturate to an SpO2 of 92%. Secondary outcomes were rate of carbon dioxide accumulation and factors affecting the risk of desaturation. MAIN RESULTS: The study was conducted in a morbidly obese population (NoAO = 41,1 kg.m-2; NPA-O2 = 42,5 kg.m-2). The risk of desaturation was signifantly lower in the intervention group (Hazzard Ratio = 0,072, 95% CI[0,019-0,283]) (Log-Rank test, p < 0.001). The median safe apnoea time was significantly longer in the intervention group (NoAO = 262 s [IQR 190-316]; NPA-O2 = 600 s [IQR 600-600]) (Mann-Whitney-U test, p < 0.001). The mean rate of CO2 accumalation was significantly slower in the intervention group (NoAO = 0,47 ± 0,14 kPa.min-1; NPA-O2 = 0,3 ± 0,09 kPa.min-1) (t-test, p = 0.003). There were no statistically significant risk factors associated with an increased risk of desaturation found. CONCLUSIONS: Nasopharyngeal apnoeic oxygenation at 18 l/min prolongs safe apnoea time, compared to preoxygenation alone, and reduces the risk of desaturation in morbidly obese patients. CLINICAL TRIAL REGISTRATION: PACTR202202665252087; WC/202004/007.

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

OBJECTIVES: We 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. METHODS: Air 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. RESULTS: Viral 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. CONCLUSION: No 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.

Mechanically Ventilated Patients With Coronavirus Disease 2019 Had a Higher Chance of In-Hospital Death If Treated With High-Flow Nasal Cannula Oxygen Before Intubation.

BACKGROUND: The impact of high-flow nasal cannula (HFNC) on outcomes of patients with respiratory failure from coronavirus disease 2019 (COVID-19) is unknown. We sought to assess whether exposure to HFNC before intubation was associated with successful extubation and in-hospital mortality compared to patients receiving intubation only. METHODS: This single-center retrospective study examined patients with COVID-19-related respiratory failure from March 2020 to March 2021 who required HFNC, intubation, or both. Data were abstracted from the electronic health record. Use and duration of HFNC and intubation were examined' as well as demographics and clinical characteristics. We assessed the association between HFNC before intubation (versus without) and chance of successful extubation and in-hospital death using Cox proportional hazards models adjusting for age, sex, race/ethnicity, obesity, hypertension, diabetes, prior chronic obstructive pulmonary disease or asthma, HCO 3 , CO 2 , oxygen-saturation-to-inspired-oxygen (S:F) ratio, pulse, respiratory rate, temperature, and length of stay before intervention. RESULTS: A total of n = 440 patients were identified, of whom 311 (70.7%) received HFNC before intubation, and 129 (29.3%) were intubated without prior use of HFNC. Patients who received HFNC before intubation had a higher chance of in-hospital death (hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.06-4.05). No difference was found in the chance of successful extubation between the 2 groups (0.70, 0.41-1.20). CONCLUSIONS: Among patients with respiratory failure from COVID-19 requiring mechanical ventilation, patients receiving HFNC before intubation had a higher chance of in-hospital death. Decisions on initial respiratory support modality should weigh the risks of intubation with potential increased mortality associated with HFNC.

Clinical Outcomes of Routine Awake Prone Positioning in COVID-19 Patients: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Before coronavirus disease 2019 (COVID-19) emerged, proning had been demonstrated to improve oxygenation in those with acute hypoxic respiratory failure and be performed in non-intensive care settings. This benefit was further exemplified by the COVID-19 pandemic, leading to awake prone positioning (APP). We assessed the efficacy of routine APP versus standard care in preventing death and invasive mechanical ventilation (IMV) in non-intubated hypoxic COVID-19 patients. PubMed, Cochrane Library, Scopus, and medRxiv databases were used from January 1st, 2020, to January 15th, 2022, to identify randomized controlled trials (RCTs). Routine APP group were encouraged to be self-prone, whereas the standard care group received care according to local clinical practice and allowed APP crossover as rescue therapy. We included eight COVID-19 RCTs assessing 809 APP vs. 822 standard care patients. APP group had less IMV requirement (26.5% vs. 30.9%; OR - odds ratio 0.77; P=0.03) than the standard care group, with subgroup analysis showing greater benefit (32.5% vs. 39.1%; OR 0.75; P=0.02) for those mainly requiring oxygen support of non-invasive mechanical ventilation (NIMV) and high-flow nasal cannula (HFNC). The time to IMV initiation was similar (mean 8.3 vs. 10.0 days; P=0.66) for patients requiring NIMV and HFNC. Patients mainly receiving supplemental oxygen and non-rebreather masks had improved oxygenation parameters, although not statistically significant. Other outcomes involving all-cause hospital mortality, hospital and ICU (intensive care unit) length of stay, and adverse events were comparable. APP appeared to be an important modality for reducing IMV requirements, especially in those requiring NIMV and HFNC.

Comparison between high-flow nasal cannula and noninvasive ventilation in COVID-19 patients: a systematic review and meta-analysis.

BACKGROUND: High-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) are important treatment approaches for acute hypoxemic respiratory failure (AHRF) in coronavirus disease 2019 (COVID-19) patients. However, the differential impact of HFNC versus NIV on clinical outcomes of COVID-19 is uncertain. OBJECTIVES: We assessed the effects of HFNC versus NIV (interface or mode) on clinical outcomes of COVID-19. METHODS: We searched PubMed, EMBASE, Web of Science, Scopus, MedRxiv, and BioRxiv for randomized controlled trials (RCTs) and observational studies (with a control group) of HFNC and NIV in patients with COVID-19-related AHRF published in English before February 2022. The primary outcome of interest was the mortality rate, and the secondary outcomes were intubation rate, PaO2/FiO2, intensive care unit (ICU) length of stay (LOS), hospital LOS, and days free from invasive mechanical ventilation [ventilator-free day (VFD)]. RESULTS: In all, 23 studies fulfilled the selection criteria, and 5354 patients were included. The mortality rate was higher in the NIV group than the HFNC group [odds ratio (OR) = 0.66, 95% confidence interval (CI): 0.51-0.84, p = 0.0008, I2 = 60%]; however, in this subgroup, no significant difference in mortality was observed in the NIV-helmet group (OR = 1.21, 95% CI: 0.63-2.32, p = 0.57, I2 = 0%) or NIV-continuous positive airway pressure (CPAP) group (OR = 0.77, 95% CI: 0.51-1.17, p = 0.23, I2 = 65%) relative to the HFNC group. There were no differences in intubation rate, PaO2/FiO2, ICU LOS, hospital LOS, or days free from invasive mechanical ventilation (VFD) between the HFNC and NIV groups. CONCLUSION: Although mortality was lower with HFNC than NIV, there was no difference in mortality between HFNC and NIV on a subgroup of helmet or CPAP group. Future large sample RCTs are necessary to prove our findings. REGISTRATION: This systematic review and meta-analysis protocol was prospectively registered with PROSPERO (no. CRD42022321997).

Impact of covid-19 on long-term oxygen therapy 2020: A nationwide study in Sweden.

INTRODUCTION: Covid-19 can cause chronic hypoxic respiratory failure, but the impact on the need for long-term oxygen therapy (LTOT) is unknown. The aim was to investigate change in incidence and characteristics of patients starting LTOT in Sweden 2020 after the outbreak of the pandemic. MATERIAL AND METHODS: Population-based observational study using data from the National Registry for Respiratory Failure (Swedevox) and from a survey to all centres prescribing LTOT in Sweden. Swedevox data provided information on incidence of LTOT and characteristics of patients starting LTOT during 2015-2020. RESULTS: Between March-Dec 2020, 131 patients started LTOT due to covid-19, corresponding to 20.5% of incident LTOT in Sweden. Compared with 2015-19, the total number of patients starting LTOT did not increase. No significant differences in patient characteristics or underlying causes of hypoxemia were found between patients starting LTOT during 2020 compared 2015-2019. The majority of the LTOT centres estimated that, since the start of the pandemic, the incidence of LTOT was unchanged and the time devoted for LTOT work was the same or slightly less. CONCLUSIONS: Covid-19 caused one fifth of all LTOT starts during the pandemic in 2020. The LTOT incidence overall did not increase possibly due to reduction in other infections.

Effectiveness of the use of a high-flow nasal cannula to treat COVID-19 patients and risk factors for failure: a meta-analysis.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has spread globally, and many patients with severe cases have received oxygen therapy through a high-flow nasal cannula (HFNC). OBJECTIVES: We assessed the efficacy of HFNC for treating patients with COVID-19 and risk factors for HFNC failure. METHODS: We searched PubMed, Embase, and the Cochrane Central Register of randomized controlled trials (RCTs) and observational studies of HFNC in patients with COVID-19 published in English from January 1st, 2020 to August 15th, 2021. The primary aim was to assess intubation, mortality, and failure rates in COVID-19 patients supported by HFNC. Secondary aims were to compare HFNC success and failure groups and to describe the risk factors for HFNC failure. RESULTS: A total of 25 studies fulfilled selection criteria and included 2851 patients. The intubation, mortality, and failure rates were 0.44 (95% confidence interval (CI): 0.38-0.51, I2 = 84%), 0.23 (95% CI: 0.19-0.29, I2 = 88%), and 0.47 (95% CI: 0.42-0.51, I2 = 56%), respectively. Compared to the success group, age, body mass index (BMI), Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE) II score, D-dimer, lactate, heart rate, and respiratory rate were higher and PaO2, PaO2/FiO2, ROX index (the ratio of SpO2/FiO2 to respiratory rate), ROX index after the initiation of HFNC, and duration of HFNC were lower in the failure group (all Ps < 0.05). There were also more smokers and more comorbidities in the failure group (all Ps < 0.05). Pooled odds ratios (ORs) revealed that older age (OR: 1.04, 95% CI: 1.01-1.07, P = 0.02, I2 = 88%), a higher white blood cell (WBC) count (OR: 1.06, 95% CI: 1.01-1.12, P = 0.02, I2 = 0%), a higher heart rate (OR: 1.42, 95% CI: 1.15-1.76, P < 0.01, I2 = 0%), and a lower ROX index(OR: 0.61, 95% CI: 0.39-0.95, P = 0.03, I2 = 93%) after the initiation of HFNC were all significant risk factors for HFNC failure. CONCLUSIONS: HFNC is an effective way of providing respiratory support in the treatment of COVID-19 patients. Older age, a higher WBC count, a higher heart rate, and a lower ROX index after the initiation of HFNC are associated with an increased risk of HFNC failure.

Clinical efficacy and safety of high-flow nasal cannula (HFNC) in acute hypoxaemic patients with COVID-19: a protocol for a systematic review and meta-analysis.

INTRODUCTION: When COVID-19 patients develop hypoxaemic respiratory failure, they often undergo early intubation. Such a potentially aerosol-generating approach places caregivers at increased risk of contracting COVID-19. This protocol aims to evaluate the clinical efficacy and safety of a high-flow nasal cannula (HFNC) for the treatment of COVID-19 patients with acute hypoxaemic respiratory failure. METHODS AND ANALYSIS: We intend to search MEDLINE, Embase, Web of Science and Cochrane Library to identify all randomised controlled trials (RCTs) on the use of HFNC in COVID-19 patients with acute respiratory failure. We will screen the RCTs against eligibility criteria for inclusion in our review. Two reviewers will independently undertake RCT selection, data extraction and risk of bias assessment. Primary outcome will be the rate of intubation, and secondary outcomes will be intensive care unit (ICU)/hospital mortality, ICU/hospital length of stay and risks of infection transmission. We will conduct meta-analyses to determine the risk ratio for dichotomous data and the mean difference (MD) or standardised MD for continuous data. Subgroup analyses will be performed based on the different quality of studies, different levels of disease severity, and the age and sex of participants. ETHICS AND DISSEMINATION: Ethical approval is not required for this study considering this is a systematic review protocol that uses only published data. The findings of this study will be disseminated through peer-reviewed publications and conference presentations. PROSPERO REGISTRATION NUMBER: CRD42021236519.

High-flow nasal cannula versus noninvasive ventilation in patients with COVID-19: a systematic review and meta-analysis.

BACKGROUND: During the novel coronavirus disease 2019 (COVID-19) pandemic raging around the world, the effectiveness of respiratory support treatment has dominated people's field of vision. This study aimed to compare the effectiveness and value of high-flow nasal cannula (HFNC) with noninvasive ventilation (NIV) for COVID-19 patients. METHODS: A comprehensive systematic review via PubMed, Web of Science, Cochrane, Scopus, WHO database, China Biology Medicine Disc (SINOMED), and China National Knowledge Infrastructure (CNKI) databases was conducted, followed by meta-analysis. RevMan 5.4 was used to analyze the results and risk of bias. The primary outcome is the number of deaths at day 28. The secondary outcomes are the occurrence of invasive mechanical ventilation (IMV), the number of deaths (no time-limited), length of intensive care unit (ICU) and hospital stay, ventilator-free days, and oxygenation index [partial pressure of arterial oxygen (PaO2)/fraction of inhaled oxygen (FiO2)] at 24 h. RESULTS: In total, nine studies [one randomized controlled trial (RCT), seven retrospective studies, and one prospective study] totaling 1582 patients were enrolled in the meta-analysis. The results showed that the incidence of IMV, number of deaths (no time-limited), and length of ICU stay were not statistically significant in the HFNC group compared with the NIV group (ps = 0.71, 0.31, and 0.33, respectively). Whereas the HFNC group performed significant advantages in terms of the number of deaths at day 28, length of hospital stay and oxygenation index (p < 0.05). Only in the ventilator-free days did NIV show advantages over the HFNC group (p < 0.0001). CONCLUSION: For COVID-19 patients, the use of HFNC therapy is associated with the reduction of the number of deaths at day 28 and length of hospital stay, and can significantly improve oxygenation index (PaO2/FiO2) at 24 h. However, there was no favorable between the HFNC and NIV groups in the occurrence of IMV. NIV group was superior only in terms of ventilator-free days.

Respiratory support after delayed cord clamping: a prospective cohort study of at-risk births at ≥35+0 weeks gestation.

OBJECTIVE: To identify risk factors associated with delivery room respiratory support in at-risk infants who are initially vigorous and received delayed cord clamping (DCC). DESIGN: Prospective cohort study. SETTING: Two perinatal centres in Melbourne, Australia. PATIENTS: At-risk infants born at ≥35+0 weeks gestation with a paediatric doctor in attendance who were initially vigorous and received DCC for >60 s. MAIN OUTCOME MEASURES: Delivery room respiratory support defined as facemask positive pressure ventilation, continuous positive airway pressure and/or supplemental oxygen within 10 min of birth. RESULTS: Two hundred and ninety-eight infants born at a median (IQR) gestational age of 39+3 (38+2-40+2) weeks were included. Cord clamping occurred at a median (IQR) of 128 (123-145) s. Forty-four (15%) infants received respiratory support at a median of 214 (IQR 156-326) s after birth. Neonatal unit admission for respiratory distress occurred in 32% of infants receiving delivery room respiratory support vs 1% of infants who did not receive delivery room respiratory support (p<0.001). Risk factors independently associated with delivery room respiratory support were average heart rate (HR) at 90-120 s after birth (determined using three-lead ECG), mode of birth and time to establish regular cries. Decision tree analysis identified that infants at highest risk had an average HR of <165 beats per minute at 90-120 s after birth following caesarean section (risk of 39%). Infants with an average HR of ≥165 beats per minute at 90-120 s after birth were at low risk (5%). CONCLUSIONS: We present a clinical decision pathway for at-risk infants who may benefit from close observation following DCC. Our findings provide a novel perspective of HR beyond the traditional threshold of 100 beats per minute.

Oxygen Therapy and Risk of Infection for Health Care Workers Caring for Patients With Viral Severe Acute Respiratory Infection: A Systematic Review and Meta-analysis.

STUDY OBJECTIVE: To synthesize the evidence regarding the infection risk associated with different modalities of oxygen therapy used in treating patients with severe acute respiratory infection. Health care workers face significant risk of infection when treating patients with a viral severe acute respiratory infection. To ensure health care worker safety and limit nosocomial transmission of such infection, it is crucial to synthesize the evidence regarding the infection risk associated with different modalities of oxygen therapy used in treating patients with severe acute respiratory infection. METHODS: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from January 1, 2000, to April 1, 2020, for studies describing the risk of infection associated with the modalities of oxygen therapy used for patients with severe acute respiratory infection. The study selection, data extraction, and quality assessment were performed by independent reviewers. The primary outcome measure was the infection of health care workers with a severe acute respiratory infection. Random-effect models were used to synthesize the extracted data. RESULTS: Of 22,123 citations, 50 studies were eligible for qualitative synthesis and 16 for meta-analysis. Globally, the quality of the included studies provided a very low certainty of evidence. Being exposed or performing an intubation (odds ratio 6.48; 95% confidence interval 2.90 to 14.44), bag-valve-mask ventilation (odds ratio 2.70; 95% confidence interval 1.31 to 5.36), and noninvasive ventilation (odds ratio 3.96; 95% confidence interval 2.12 to 7.40) were associated with an increased risk of infection. All modalities of oxygen therapy generate air dispersion. CONCLUSION: Most modalities of oxygen therapy are associated with an increased risk of infection and none have been demonstrated as safe. The lowest flow of oxygen should be used to maintain an adequate oxygen saturation for patients with severe acute respiratory infection, and manipulation of oxygen delivery equipment should be minimized.

Predictors of failure of high flow nasal cannula failure in acute hypoxemic respiratory failure due to COVID-19.

Hypoxemic respiratory failure is a common manifestation of COVID-19 pneumonia. Early in the COVID-19 pandemic, patients with hypoxemic respiratory failure were, at times, being intubated earlier than normal; in part because the options of heated humidified high flow nasal cannula (HFNC) and non-invasive ventilation (NIV) were considered potentially inadequate and to increase risk of virus aerosolization. To understand the benefits and factors that predict success and failure of HFNC in this population, we evaluated data from the first 30 sequential patients admitted with COVID-19 pneumonia to our center who were managed with HFNC. We conducted Cox Proportional Hazards regression models to evaluate the factors associated with high flow nasal cannula failure (outcome variable), using time to intubation (censoring variable), while adjusting for comorbidities and immunosuppression. In the majority of our patients (76.7%), the use of HFNC failed and the patients were ultimately placed on mechanical ventilation. Those at increased risk of failure had a higher sequential organ failure assessment score, and at least one comorbidity or history of immunosuppression. Our data suggest that high flow nasal cannula may have a role in some patients with COVID-19 presenting with hypoxemic respiratory failure, but careful patient selection is the likely key to its success.

High-flow nasal cannulae for respiratory support in adult intensive care patients.

BACKGROUND: High-flow nasal cannulae (HFNC) deliver high flows of blended humidified air and oxygen via wide-bore nasal cannulae and may be useful in providing respiratory support for adults experiencing acute respiratory failure, or at risk of acute respiratory failure, in the intensive care unit (ICU). This is an update of an earlier version of the review. OBJECTIVES: To assess the effectiveness of HFNC compared to standard oxygen therapy, or non-invasive ventilation (NIV) or non-invasive positive pressure ventilation (NIPPV), for respiratory support in adults in the ICU. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, CINAHL, Web of Science, and the Cochrane COVID-19 Register (17 April 2020), clinical trial registers (6 April 2020) and conducted forward and backward citation searches. SELECTION CRITERIA: We included randomized controlled studies (RCTs) with a parallel-group or cross-over design comparing HFNC use versus other types of non-invasive respiratory support (standard oxygen therapy via nasal cannulae or mask; or NIV or NIPPV which included continuous positive airway pressure and bilevel positive airway pressure) in adults admitted to the ICU. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures as expected by Cochrane. MAIN RESULTS: We included 31 studies (22 parallel-group and nine cross-over designs) with 5136 participants; this update included 20 new studies. Twenty-one studies compared HFNC with standard oxygen therapy, and 13 compared HFNC with NIV or NIPPV; three studies included both comparisons. We found 51 ongoing studies (estimated 12,807 participants), and 19 studies awaiting classification for which we could not ascertain study eligibility information. In 18 studies, treatment was initiated after extubation. In the remaining studies, participants were not previously mechanically ventilated. HFNC versus standard oxygen therapy HFNC may lead to less treatment failure as indicated by escalation to alternative types of oxygen therapy (risk ratio (RR) 0.62, 95% confidence interval (CI) 0.45 to 0.86; 15 studies, 3044 participants; low-certainty evidence). HFNC probably makes little or no difference in mortality when compared with standard oxygen therapy (RR 0.96, 95% CI 0.82 to 1.11; 11 studies, 2673 participants; moderate-certainty evidence). HFNC probably results in little or no difference to cases of pneumonia (RR 0.72, 95% CI 0.48 to 1.09; 4 studies, 1057 participants; moderate-certainty evidence), and we were uncertain of its effect on nasal mucosa or skin trauma (RR 3.66, 95% CI 0.43 to 31.48; 2 studies, 617 participants; very low-certainty evidence). We found low-certainty evidence that HFNC may make little or no difference to the length of ICU stay according to the type of respiratory support used (MD 0.12 days, 95% CI -0.03 to 0.27; 7 studies, 1014 participants). We are uncertain whether HFNC made any difference to the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) within 24 hours of treatment (MD 10.34 mmHg, 95% CI -17.31 to 38; 5 studies, 600 participants; very low-certainty evidence). We are uncertain whether HFNC made any difference to short-term comfort (MD 0.31, 95% CI -0.60 to 1.22; 4 studies, 662 participants, very low-certainty evidence), or to long-term comfort (MD 0.59, 95% CI -2.29 to 3.47; 2 studies, 445 participants, very low-certainty evidence). HFNC versus NIV or NIPPV We found no evidence of a difference between groups in treatment failure when HFNC were used post-extubation or without prior use of mechanical ventilation (RR 0.98, 95% CI 0.78 to 1.22; 5 studies, 1758 participants; low-certainty evidence), or in-hospital mortality (RR 0.92, 95% CI 0.64 to 1.31; 5 studies, 1758 participants; low-certainty evidence). We are very uncertain about the effect of using HFNC on incidence of pneumonia (RR 0.51, 95% CI 0.17 to 1.52; 3 studies, 1750 participants; very low-certainty evidence), and HFNC may result in little or no difference to barotrauma (RR 1.15, 95% CI 0.42 to 3.14; 1 study, 830 participants; low-certainty evidence). HFNC may make little or no difference to the length of ICU stay (MD -0.72 days, 95% CI -2.85 to 1.42; 2 studies, 246 participants; low-certainty evidence). The ratio of PaO2/FiO2 may be lower up to 24 hours with HFNC use (MD -58.10 mmHg, 95% CI -71.68 to -44.51; 3 studies, 1086 participants; low-certainty evidence). We are uncertain whether HFNC improved short-term comfort when measured using comfort scores (MD 1.33, 95% CI 0.74 to 1.92; 2 studies, 258 participants) and responses to questionnaires (RR 1.30, 95% CI 1.10 to 1.53; 1 study, 168 participants); evidence for short-term comfort was very low certainty. No studies reported on nasal mucosa or skin trauma. AUTHORS' CONCLUSIONS: HFNC may lead to less treatment failure when compared to standard oxygen therapy, but probably makes little or no difference to treatment failure when compared to NIV or NIPPV. For most other review outcomes, we found no evidence of a difference in effect. However, the evidence was often of low or very low certainty. We found a large number of ongoing studies; including these in future updates could increase the certainty or may alter the direction of these effects.

ANTECEDENTES: Las cánulas nasales de alto flujo (HFNC) administran flujos elevados de una mezcla humedecida de aire y oxígeno a través de cánulas nasales de gran calibre y pueden ser útiles para proporcionar asistencia respiratoria a los adultos que presentan insuficiencia respiratoria aguda, o que tienen riesgo de presentarla, en la unidad de cuidados intensivos (UCI). Esta es una actualización de una versión anterior de la revisión. OBJETIVOS: Evaluar la eficacia de las HFNC en comparación con la oxigenoterapia estándar, o la ventilación no invasiva (VNI) o la ventilación con presión positiva no invasiva (VPPNI), para la asistencia respiratoria de adultos en la UCI. MÉTODOS DE BÚSQUEDA: Se realizaron búsquedas en CENTRAL, MEDLINE, Embase, CINAHL, Web of Science y en el Registro Cochrane de covid­19 (17 de abril de 2020), registros de ensayos clínicos (6 de abril de 2020) y se realizaron búsquedas de citas prospectivas y retrospectivas. CRITERIOS DE SELECCIÓN: Se incluyeron los estudios controlados aleatorizados (ECA) con un diseño de grupos paralelos o cruzados que compararon el uso de HFNC versus otro tipo de asistencia respiratoria no invasiva (oxigenoterapia estándar a través de cánulas nasales o mascarilla; o VNI o VPPNI que incluía la presión positiva continua en las vías respiratorias y la presión positiva de dos niveles en las vías respiratorias) en adultos ingresados en la UCI. OBTENCIÓN Y ANÁLISIS DE LOS DATOS: Se utilizaron los procedimientos metodológicos estándar previstos por la Colaboración Cochrane. RESULTADOS PRINCIPALES: Se incluyeron 31 estudios (22 de grupos paralelos y nueve de diseño cruzado) con 5136 participantes; esta actualización incluyó 20 estudios nuevos. Veintiún estudios compararon la HFNC con la oxigenoterapia estándar, y 13 compararon la HFNC con la VNI o la VPPNI; tres estudios incluyeron ambas comparaciones. Se encontraron 51 estudios en curso (con una estimación de 12 807 participantes) y 19 estudios en espera de clasificación en los que no fue posible determinar la información de elegibilidad del estudio. En 18 estudios el tratamiento se inició después de la extubación. En el resto de los estudios, los participantes no habían recibido de forma previa ventilación mecánica. HFNC versus oxigenoterapia estándar La HFNC podría conducir a un menor fracaso del tratamiento, según lo indicado por el escalamiento a tipos alternativos de oxigenoterapia (razón de riesgos [RR] 0,62; intervalo de confianza [IC] del 95%: 0,45 a 0,86; 15 estudios, 3044 participantes; evidencia de certeza baja). La HFNC probablemente da lugar a poca o ninguna diferencia en la mortalidad cuando se compara con la oxigenoterapia estándar (RR 0,96; IC del 95%: 0,82 a 1,11; 11 estudios, 2673 participantes; evidencia de certeza moderada). La HFNC probablemente da lugar a poca o ninguna diferencia con respecto a los casos de neumonía (RR 0,72; IC del 95%: 0,48 a 1,09; cuatro estudios, 1057 participantes; evidencia de certeza moderada), y no se sabe con certeza su efecto sobre la mucosa nasal ni el traumatismo cutáneo (RR 3,66; IC del 95%: 0,43 a 31,48; dos estudios, 617 participantes; evidencia de certeza muy baja). Se encontró evidencia de certeza baja de que la HFNC podría dar lugar a poca o ninguna diferencia en la duración de la estancia en la UCI según el tipo de asistencia respiratoria utilizada (DM 0,12 días; IC del 95%: ­0,03 a 0,27; siete estudios, 1014 participantes). No se sabe con certeza si la HFNC dio lugar a alguna diferencia en el cociente entre la presión parcial de oxígeno arterial y la fracción de oxígeno inspirado (PaO2/FiO2) en las primeras 24 horas del tratamiento (DM 10,34 mmHg; IC del 95%: ­17,31 a 38; cinco estudios, 600 participantes; evidencia de certeza muy baja). No se sabe con certeza si la HFNC dio lugar a alguna diferencia en la comodidad a corto plazo (DM 0,31; IC del 95%: ­0,60 a 1,22; cuatro estudios, 662 participantes, evidencia de certeza muy baja), o en la comodidad a largo plazo (DM 0,59; IC del 95%: ­2,29 a 3,47; dos estudios, 445 participantes, evidencia de certeza muy baja). HFNC versus VNI o VPPNI No se encontró evidencia de una diferencia entre los grupos en el fracaso del tratamiento cuando se utilizó la HFNC después de la extubación o sin el uso previo de ventilación mecánica (RR 0,98; IC del 95%: 0,78 a 1,22; cinco estudios, 1758 participantes; evidencia de certeza baja), ni en la mortalidad hospitalaria (RR 0,92; IC del 95%: 0,64 a 1,31; cinco estudios, 1758 participantes; evidencia de certeza baja). No hay certeza sobre el efecto del uso de la HFNC en la incidencia de la neumonía (RR 0,51; IC del 95%: 0,17 a 1,52; tres estudios, 1750 participantes; evidencia de certeza muy baja), y la HFNC podría dar lugar a poca o ninguna diferencia en el barotraumatismo (RR 1,15; IC del 95%: 0,42 a 3,14; un estudio, 830 participantes; evidencia de certeza baja). La HFNC podría suponer una diferencia escasa o nula en la duración de la estancia en la UCI (DM ­0,72 días; IC del 95%: ­2,85 a 1,42; dos estudios, 246 participantes; evidencia de certeza baja). El cociente PaO2/FiO2 podría ser menor hasta 24 horas con el uso de la HFNC (DM ­58,10 mmHg; IC del 95%: ­71,68 a ­44,51; tres estudios, 1086 participantes; evidencia de certeza baja). No se sabe si la HFNC mejoró la comodidad a corto plazo cuando se midió mediante puntuaciones de comodidad (DM 1,33; IC del 95%: 0,74 a 1,92; dos estudios, 258 participantes) y respuestas a cuestionarios (RR 1,30; IC del 95%: 1,10 a 1,53; un estudio, 168 participantes); la evidencia para la comodidad a corto plazo fue de certeza muy baja. Ningún estudio informó sobre la mucosa nasal ni el traumatismo cutáneo. CONCLUSIONES DE LOS AUTORES: La HFNC podría dar lugar a un menor fracaso del tratamiento en comparación con la oxigenoterapia estándar, pero probablemente suponga una escasa o nula diferencia en el fracaso del tratamiento en comparación con la VNI o la VPPNI. Para la mayoría de los demás desenlaces de la revisión, no se encontró evidencia de una diferencia en el efecto. Sin embargo, la certeza de la evidencia se consideró baja o muy baja. Se encontró un gran número de estudios en curso; incluirlos en futuras actualizaciones podría aumentar la certeza o podría alterar la dirección de estos efectos.

Spontaneous Pneumothorax in COVID-19 Patients Treated with High-Flow Nasal Cannula outside the ICU: A Case Series.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic and a burden to global health at the turn of 2019 and 2020. No targeted treatment for COVID-19 infection has been identified so far, thus supportive treatment, invasive and non-invasive oxygen support, and corticosteroids remain a common therapy. High-flow nasal cannula (HFNC), a non-invasive oxygen support method, has become a prominent treatment option for respiratory failure during the SARS-CoV-2 pandemic. HFNC reduces the anatomic dead space and increases positive end-expiratory pressure (PEEP), allowing higher concentrations and higher flow of oxygen. Some studies suggest positive effects of HFNC on mortality and avoidance of intubation. Spontaneous pneumothorax has been observed in patients suffering from SARS-CoV-2 pneumonia. Although the viral infection itself contributes to its development, higher PEEP generated by both HFNC and mechanical ventilation is another risk factor for increased alveoli damage and air-leak. Herein, we present three cases of patients with no previous history of lung diseases who were diagnosed with COVID-19 viral pneumonia. All of them were supported with HFNC, and all of them presented spontaneous pneumothorax.

Assessment of dispersion of airborne particles of oral/nasal fluid by high flow nasal cannula therapy.

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.

The independent factors associated with oxygen therapy in COVID-19 patients under 65 years old.

BACKGROUND: The number of hospitalized young coronavirus disease 2019 (COVID-19) patients has increased significantly. However, specific data about COVID-19 patients under 65 years old who are admitted to the hospital are scarce. METHODS: The COVID-19 patients under 65 years old who were admitted to the hospital in Sichuan Province, Renmin Hospital of Wuhan University, and Wuhan Red Cross Hospital were included in this study. Demographic information, laboratory data and clinical treatment courses were extracted from electronic medical records. Risk factors associated with oxygen therapy were explored. RESULTS: Eight hundred thirty-three COVID-19 patients under 65 years old were included. Of the included patients, 29.4% had one or more comorbidities. Oxygen therapy was required in 63.1% of these patients, and the mortality was 2.9% among the oxygen therapy patients. Fever (odds ratio [OR] 2.072, 95% confidence interval [CI] 1.312-3.271, p = 0.002), dyspnea (OR 2.522, 95% CI 1.213-5.243, p = 0.013), chest distress (OR 2.278, 95% CI 1.160-4.473, p = 0.017), elevated respiratory rate (OR 1.114, 95% CI 1.010-1.228, p = 0.031), and decreased albumin (OR 0.932, 95% CI 0.880-0.987, p = 0.016) and globulin levels (OR 0.929, 95% 0.881-0.980, p = 0.007) were independent factors related to oxygen therapy. CONCLUSIONS: Oxygen therapy is highly required in COVID-19 patients under 65 years old who are admitted to the hospital, but the success rate is high. Respiratory failure-related symptoms, elevated respiratory rate, low albumin and globulin levels, and fever at admission are independent risk factors related to the requirement of oxygen.

Therapeutic interventions for COVID-19: a living overview of reviews.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has rapidly spread worldwide, but safe and effective treatment options remain unavailable. Numerous systematic reviews of varying qualities have tried to summarize the evidence on the available therapeutic interventions for COVID-19. This overview of reviews aims to provide a succinct summary of the findings of systematic reviews on different pharmacological and non-pharmacological therapeutic interventions for COVID-19. METHODS: We searched PubMed, Embase, Google Scholar, Cochrane Database of Systematic Reviews, and WHO database of publications on COVID-19 from 1 December 2019 through to 11 June 2020 for peer-reviewed systematic review studies that reported on potential pharmacological or non-pharmacological therapies for COVID-19. Quality assessment was completed using A MeaSurement Tool to Assess systematic Reviews-2 (AMSTAR-2) measure. RESULTS: Out of 816 non-duplicate studies, 45 were included in the overview. Antiviral and antibiotic agents, corticosteroids, and anti-malarial agents were the most common drug classes used to treat COVID-19; however, there was no direct or strong evidence to support their efficacy. Oxygen therapy and ventilatory support was the most common non-pharmacological supportive care. The quality of most of the included reviews was rated as low or critically low. CONCLUSION: This overview of reviews demonstrates that although some therapeutic interventions may be beneficial to specific subgroups of COVID-19 patients, the available data are insufficient to strongly recommend any particular treatment option to be used at a population level. Future systematic reviews on COVID-19 treatments should adhere to the recommended systematic review methodologies and ensure that promptness and comprehensiveness are balanced.The reviews of this paper are available via the supplemental material section.

Oxygen therapy strategies and techniques to treat hypoxia in COVID-19 patients.

OBJECTIVE: Hypoxia is one of the primary causes that leads to multiple organ injuries and death in COVID-19 patients. Aggressive oxygen therapy for the treatment of hypoxia is important in saving these patients. We have summarized the mechanisms, efficacy, and side effects of various oxygen therapy techniques and their status or the potential to treat hypoxia in COVID-19 patients. The benefit to risk ratio of each oxygen therapy technique and strategy to use them in COVID-19 patients are discussed. High flow nasal cannula oxygen (HFNO) should be considered a better choice as an early stage oxygen therapy. Supraglottic jet oxygenation and ventilation (SJOV) is a promising alternative for HFNO with potential benefits.