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1.
Can J Anaesth ; 67(9): 1217-1248, 2020 Sep.
Article in English | MEDLINE | ID: covidwho-1536371

ABSTRACT

PURPOSE: We conducted two World Health Organization-commissioned reviews to inform use of high-flow nasal cannula (HFNC) in patients with coronavirus disease (COVID-19). We synthesized the evidence regarding efficacy and safety (review 1), as well as risks of droplet dispersion, aerosol generation, and associated transmission (review 2) of viral products. SOURCE: Literature searches were performed in Ovid MEDLINE, Embase, Web of Science, Chinese databases, and medRxiv. Review 1: we synthesized results from randomized-controlled trials (RCTs) comparing HFNC to conventional oxygen therapy (COT) in critically ill patients with acute hypoxemic respiratory failure. Review 2: we narratively summarized findings from studies evaluating droplet dispersion, aerosol generation, or infection transmission associated with HFNC. For both reviews, paired reviewers independently conducted screening, data extraction, and risk of bias assessment. We evaluated certainty of evidence using GRADE methodology. PRINCIPAL FINDINGS: No eligible studies included COVID-19 patients. Review 1: 12 RCTs (n = 1,989 patients) provided low-certainty evidence that HFNC may reduce invasive ventilation (relative risk [RR], 0.85; 95% confidence interval [CI], 0.74 to 0.99) and escalation of oxygen therapy (RR, 0.71; 95% CI, 0.51 to 0.98) in patients with respiratory failure. Results provided no support for differences in mortality (moderate certainty), or in-hospital or intensive care length of stay (moderate and low certainty, respectively). Review 2: four studies evaluating droplet dispersion and three evaluating aerosol generation and dispersion provided very low certainty evidence. Two simulation studies and a crossover study showed mixed findings regarding the effect of HFNC on droplet dispersion. Although two simulation studies reported no associated increase in aerosol dispersion, one reported that higher flow rates were associated with increased regions of aerosol density. CONCLUSIONS: High-flow nasal cannula may reduce the need for invasive ventilation and escalation of therapy compared with COT in COVID-19 patients with acute hypoxemic respiratory failure. This benefit must be balanced against the unknown risk of airborne transmission.


RéSUMé: OBJECTIF: Nous avons réalisé deux comptes rendus sur commande de l'Organisation mondiale de la santé pour guider l'utilisation de canules nasales à haut débit (CNHD) chez les patients ayant contracté le coronavirus (COVID-19). Nous avons synthétisé les données probantes concernant leur efficacité et leur innocuité (compte rendu 1), ainsi que les risques de dispersion des gouttelettes, de génération d'aérosols, et de transmission associée d'éléments viraux (compte rendu 2). SOURCE: Des recherches de littérature ont été réalisées dans les bases de données Ovid MEDLINE, Embase, Web of Science, ainsi que dans les bases de données chinoises et medRxiv. Compte rendu 1 : nous avons synthétisé les résultats d'études randomisées contrôlées (ERC) comparant les CNHD à une oxygénothérapie conventionnelle chez des patients en état critique atteints d'insuffisance respiratoire hypoxémique aiguë. Compte rendu 2 : nous avons résumé sous forme narrative les constatations d'études évaluant la dispersion de gouttelettes, la génération d'aérosols ou la transmission infectieuse associées aux CNHD. Pour les deux comptes rendus, des réviseurs appariés ont réalisé la sélection des études, l'extraction des données et l'évaluation du risque de biais de manière indépendante. Nous avons évalué la certitude des données probantes en nous fondant sur la méthodologie GRADE. CONSTATATIONS PRINCIPALES: Aucune étude éligible n'incluait de patients atteints de COVID-19. Compte rendu 1 : 12 ERC (n = 1989 patients) ont fourni des données probantes de certitude faible selon lesquelles les CNHD réduiraient la ventilation invasive (risque relatif [RR], 0,85; intervalle de confiance [IC] 95 %, 0,74 à 0,99) et l'intensification de l'oxygénothérapie (RR, 0,71; IC 95 %, 0,51 à 0,98) chez les patients atteints d'insuffisance respiratoire. Les résultats n'ont pas démontré de différences en matière de mortalité (certitude modérée), ni de durée du séjour hospitalier ou à l'unité des soins intensifs (certitude modérée et faible, respectivement). Compte rendu 2 : quatre études évaluant la dispersion de gouttelettes et trois évaluant la génération et la dispersion d'aérosols ont fourni des données probantes de très faible certitude. Deux études de simulation et une étude croisée ont donné des résultats mitigés quant à l'effet des CNHD sur la dispersion des gouttelettes. Bien que deux études de simulation n'aient rapporté aucune augmentation associée concernant la dispersion d'aérosols, l'une a rapporté que des taux de débit plus élevés étaient associés à des régions à densité d'aérosols élevée plus grandes. CONCLUSION: Les canules nasales à haut débit pourraient réduire la nécessité de recourir à la ventilation invasive et l'escalade des traitements par rapport à l'oxygénothérapie conventionnelle chez les patients atteints de COVID-19 souffrant d'insuffisance respiratoire hypoxémique aiguë. Cet avantage doit être soupesé contre le risque inconnu de transmission atmosphérique.


Subject(s)
Coronavirus Infections/therapy , Oxygen Inhalation Therapy/methods , Pneumonia, Viral/therapy , Respiratory Insufficiency/therapy , Aerosols , COVID-19 , Cannula , Coronavirus Infections/complications , Coronavirus Infections/mortality , Humans , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/mortality , Randomized Controlled Trials as Topic , Respiratory Insufficiency/physiopathology , Respiratory Insufficiency/virology
2.
BMJ Open ; 11(3): e040616, 2021 03 17.
Article in English | MEDLINE | ID: covidwho-1140331

ABSTRACT

OBJECTIVES: SARS-CoV-2-related disease, referred to as COVID-19, has emerged as a global pandemic since December 2019. While there is growing recognition regarding possible airborne transmission, particularly in the setting of aerosol-generating procedures and treatments, whether nasopharyngeal and oropharyngeal swabs for SARS-CoV-2 generate aerosols remains unclear. DESIGN: Systematic review. DATA SOURCES: We searched Ovid MEDLINE and EMBASE up to 3 November 2020. We also searched the China National Knowledge Infrastructure, Chinese Medical Journal Network, medRxiv and ClinicalTrials.gov up to 29 March 2020. ELIGIBILITY CRITERIA: All comparative and non-comparative studies that evaluated dispersion or aerosolisation of viable airborne organisms, or transmission of infection associated with nasopharyngeal or oropharyngeal swab testing. RESULTS: Of 7702 citations, only one study was deemed eligible. Using a dedicated sampling room with negative pressure isolation room, personal protective equipment including N95 or higher masks, strict sterilisation protocols, structured training with standardised collection methods and a structured collection and delivery system, a tertiary care hospital proved a 0% healthcare worker infection rate among eight nurses conducting over 11 000 nasopharyngeal swabs. No studies examining transmissibility with other safety protocols, nor any studies quantifying the risk of aerosol generation with nasopharyngeal or oropharyngeal swabs for detection of SARS-CoV-2, were identified. CONCLUSIONS: There is limited to no published data regarding aerosol generation and risk of transmission with nasopharyngeal and oropharyngeal swabs for the detection of SARS-CoV-2. Field experiments to quantify this risk are warranted. Vigilance in adhering to current standards for infection control is suggested.


Subject(s)
Aerosols , COVID-19 Testing/instrumentation , COVID-19/diagnosis , COVID-19/transmission , Humans , Infection Control , Nasopharynx/virology , Oropharynx/virology , Pandemics
3.
Canadian Journal of Anaesthesia ; 2020.
Article | WHO COVID | ID: covidwho-608089

ABSTRACT

PURPOSE: We conducted two World Health Organization-commissioned reviews to inform use of high-flow nasal cannula (HFNC) in patients with coronavirus disease (COVID-19). We synthesized the evidence regarding efficacy and safety (review 1), as well as risks of droplet dispersion, aerosol generation, and associated transmission (review 2) of viral products. SOURCE: Literature searches were performed in Ovid MEDLINE, Embase, Web of Science, Chinese databases, and medRxiv. Review 1: we synthesized results from randomized-controlled trials (RCTs) comparing HFNC to conventional oxygen therapy (COT) in critically ill patients with acute hypoxemic respiratory failure. Review 2: we narratively summarized findings from studies evaluating droplet dispersion, aerosol generation, or infection transmission associated with HFNC. For both reviews, paired reviewers independently conducted screening, data extraction, and risk of bias assessment. We evaluated certainty of evidence using GRADE methodology. PRINCIPAL FINDINGS: No eligible studies included COVID-19 patients. Review 1: 12 RCTs (n = 1,989 patients) provided low-certainty evidence that HFNC may reduce invasive ventilation (relative risk [RR], 0.85;95% confidence interval [CI], 0.74 to 0.99) and escalation of oxygen therapy (RR, 0.71;95% CI, 0.51 to 0.98) in patients with respiratory failure. Results provided no support for differences in mortality (moderate certainty), or in-hospital or intensive care length of stay (moderate and low certainty, respectively). Review 2: four studies evaluating droplet dispersion and three evaluating aerosol generation and dispersion provided very low certainty evidence. Two simulation studies and a crossover study showed mixed findings regarding the effect of HFNC on droplet dispersion. Although two simulation studies reported no associated increase in aerosol dispersion, one reported that higher flow rates were associated with increased regions of aerosol density. CONCLUSIONS: High-flow nasal cannula may reduce the need for invasive ventilation and escalation of therapy compared with COT in COVID-19 patients with acute hypoxemic respiratory failure. This benefit must be balanced against the unknown risk of airborne transmission.

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