scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Evaluation of droplet dispersion during non-invasive ventilation, oxygen therapy, nebuliser treatment and chest physiotherapy in clinical practice: implications for management of pandemic influenza and other airborne infections

01 Oct 2010-Health Technology Assessment (Health Technol Assess)-Vol. 14, Iss: 46, pp 131-172
TL;DR: The findings suggest that health-care workers providing NIV and chest physiotherapy, working within 1 m of an infected patient should have a higher level of respiratory protection, but that infection control measures designed to limit aerosol spread may have less relevance for these procedures.
Abstract: Background Influenza viruses are thought to be spread by droplets, but the role of aerosol dissemination is unclear and has not been assessed by previous studies. Oxygen therapy, nebulised medication and ventilatory support are treatments used in clinical practice to treat influenzal infection are thought to generate droplets or aerosols. Objectives Evaluation of the characteristics of droplet/aerosol dispersion around delivery systems during non-invasive ventilation (NIV), oxygen therapy, nebuliser treatment and chest physiotherapy by measuring droplet size, geographical distribution of droplets, decay in droplets over time after the interventions were discontinued. Methods Three groups were studied: (1) normal controls, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation. Each group received oxygen therapy, NIV using a vented mask system and a modified circuit with non-vented mask and exhalation filter, and nebulised saline. The patient group had a period of standardised chest physiotherapy treatment. Droplet counts in mean diameter size ranges from 0.3 to > 10 µm were measured with an counter placed adjacent to the face and at a 1-m distance from the subject/patient, at the height of the nose/mouth of an average health-care worker. Results NIV using a vented mask produced droplets in the large size range (> 10 µm) in patients (p = 0.042) and coryzal subjects (p = 0.044) compared with baseline values, but not in normal controls (p = 0.379), but this increase in large droplets was not seen using the NIV circuit modification. Chest physiotherapy produced droplets predominantly of > 10 µm (p = 0.003), which, as with NIV droplet count in the patients, had fallen significantly by 1 m. Oxygen therapy did not increase droplet count in any size range. Nebulised saline delivered droplets in the small- and medium-size aerosol/droplet range, but did not increase large-size droplet count. Conclusions NIV and chest physiotherapy are droplet (not aerosol)-generating procedures, producing droplets of > 10 µm in size. Due to their large mass, most fall out on to local surfaces within 1 m. The only device producing an aerosol was the nebuliser and the output profile is consistent with nebuliser characteristics rather than dissemination of large droplets from patients. These findings suggest that health-care workers providing NIV and chest physiotherapy, working within 1 m of an infected patient should have a higher level of respiratory protection, but that infection control measures designed to limit aerosol spread may have less relevance for these procedures. These results may have infection control implications for other airborne infections, such as severe acute respiratory syndrome and tuberculosis, as well as for pandemic influenza infection.
Citations
More filters
Journal ArticleDOI
TL;DR: Streamlining of workflows for rapid diagnosis and isolation, clinical management, and infection prevention will matter not only to patients with COVID-19, but also to health-care workers and other patients who are at risk from nosocomial transmission.

1,147 citations


Cites background from "Evaluation of droplet dispersion du..."

  • ...35 Suggestions that HFNC might be safe are questionable: studies that might be taken to support the safety of HFNC were not designed to show whether or not HFNC is aerosol generating and did not examine the spread of viruses....

    [...]

  • ...[34] [35] [36] [37] The risk of nosocomial transmission in shared ICU rooms should be studied....

    [...]

Journal ArticleDOI
TL;DR: An overview of the management of patients with COPD during the COVID-19 pandemic is presented and inhaled corticosteroids, long-acting bronchodilators, roflumilast, or chronic macrolides should be used as indicated for stable COPD management.
Abstract: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has raised many questions about the management of patients with chronic obstructive pulmonary disease (COPD) and whether modifications of their therapy are required. It has raised questions about recognizing and differentiating coronavirus disease (COVID-19) from COPD given the similarity of the symptoms. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) Science Committee used established methods for literature review to present an overview of the management of patients with COPD during the COVID-19 pandemic. It is unclear whether patients with COPD are at increased risk of becoming infected with SARS-CoV-2. During periods of high community prevalence of COVID-19, spirometry should only be used when it is essential for COPD diagnosis and/or to assess lung function status for interventional procedures or surgery. Patients with COPD should follow basic infection control measures, including social distancing, hand washing, and wearing a mask or face covering. Patients should remain up to date with appropriate vaccinations, particularly annual influenza vaccination. Although data are limited, inhaled corticosteroids, long-acting bronchodilators, roflumilast, or chronic macrolides should continue to be used as indicated for stable COPD management. Systemic steroids and antibiotics should be used in COPD exacerbations according to the usual indications. Differentiating symptoms of COVID-19 infection from chronic underlying symptoms or those of an acute COPD exacerbation may be challenging. If there is suspicion for COVID-19, testing for SARS-CoV-2 should be considered. Patients who developed moderate-to-severe COVID-19, including hospitalization and pneumonia, should be treated with evolving pharmacotherapeutic approaches as appropriate, including remdesivir, dexamethasone, and anticoagulation. Managing acute respiratory failure should include appropriate oxygen supplementation, prone positioning, noninvasive ventilation, and protective lung strategy in patients with COPD and severe acute respiratory distress syndrome. Patients who developed asymptomatic or mild COVID-19 should be followed with the usual COPD protocols. Patients who developed moderate or worse COVID-19 should be monitored more frequently and accurately than the usual patients with COPD, with particular attention to the need for oxygen therapy.

345 citations


Cites background from "Evaluation of droplet dispersion du..."

  • ...Although most of the aerosol emitted comes from the device (80, 81), there is a risk that patients may exhale contaminated aerosol and droplets produced by coughing when using a nebulizer and may be dispersed more widely by the driving gas....

    [...]

Journal ArticleDOI
TL;DR: Biological plausibility of aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious person, the pathogen remains viable in the environment for some period of time, and the target tissues in which the pathogenic initiates infection are accessible to the aerosol.
Abstract: Objective: The concept of aerosol transmission is developed to resolve limitations in conventional definitions of airborne and droplet transmission. Methods: The method was literature review. Results: An infectious aerosol is a collection of pathogen-laden particles in air. Aerosol particles may deposit onto or be inhaled by a susceptible person. Aerosol transmission is biologically plausible when infectious aerosols are generated by or from an infectious person, the pathogen remains viable in the environment for some period of time, and the target tissues in which the pathogen initiates infection are accessible to the aerosol. Biological plausibility of aerosol transmission is evaluated for Severe Acute Respiratory Syndrome coronavirus and norovirus and discussed for Mycobacterium tuberculosis, influenza, and Ebola virus. Conclusions: Aerosol transmission reflects a modern understanding of aerosol science and allows physically appropriate explanation and intervention selection for infectious diseases.

290 citations

Journal ArticleDOI
TL;DR: A scoring system is described that systematically integrates factors to facilitate decision-making and triage for MeNTS procedures, and appropriately weighs individual patient risks with the ethical necessity of optimizing public health concerns.
Abstract: Hospitals have severely curtailed the performance of nonurgent surgical procedures in anticipation of the need to redeploy healthcare resources to meet the projected massive medical needs of patients with coronavirus disease 2019 (COVID-19). Surgical treatment of non-COVID-19 related disease during this period, however, still remains necessary. The decision to proceed with medically necessary, time-sensitive (MeNTS) procedures in the setting of the COVID-19 pandemic requires incorporation of factors (resource limitations, COVID-19 transmission risk to providers and patients) heretofore not overtly considered by surgeons in the already complicated processes of clinical judgment and shared decision-making. We describe a scoring system that systematically integrates these factors to facilitate decision-making and triage for MeNTS procedures, and appropriately weighs individual patient risks with the ethical necessity of optimizing public health concerns. This approach is applicable across a broad range of hospital settings (academic and community, urban and rural) in the midst of the pandemic and may be able to inform case triage as operating room capacity resumes once the acute phase of the pandemic subsides.

284 citations


Cites background from "Evaluation of droplet dispersion du..."

  • ...Obstructive sleep apnea (OSA) is included in the group because patients with OSA are at increased risk of postoperative respiratory impairment(22,23) and the aerosolization risk associated with the use of some positive airway pressure devices.(16)...

    [...]

Journal ArticleDOI
TL;DR: This rapid guideline is to provide recommendations on the organizational management of intensive care units caring for patients with COVID-19 including: planning arisis surge response; crisis surge response strategies; triage, supporting families, and staff.
Abstract: Given the rapidly changing nature of COVID-19, clinicians and policy makers require urgent review and summary of the literature, and synthesis of evidence-based guidelines to inform practice. The WHO advocates for rapid reviews in these circumstances. The purpose of this rapid guideline is to provide recommendations on the organizational management of intensive care units caring for patients with COVID-19 including: planning a crisis surge response; crisis surge response strategies; triage, supporting families, and staff.

277 citations

References
More filters
Journal ArticleDOI
TL;DR: Airborne spread of the virus appears to explain this large community outbreak of SARS in Hong Kong, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus.
Abstract: background There is uncertainty about the mode of transmission of the severe acute respiratory syndrome (SARS) virus. We analyzed the temporal and spatial distributions of cases in a large community outbreak of SARS in Hong Kong and examined the correlation of these data with the three-dimensional spread of a virus-laden aerosol plume that was modeled using studies of airflow dynamics. methods We determined the distribution of the initial 187 cases of SARS in the Amoy Gardens housing complex in 2003 according to the date of onset and location of residence. We then studied the association between the location (building, floor, and direction the apartment unit faced) and the probability of infection using logistic regression. The spread of the airborne, virus-laden aerosols generated by the index patient was modeled with the use of airflow-dynamics studies, including studies performed with the use of computational fluid-dynamics and multizone modeling. results The curves of the epidemic suggested a common source of the outbreak. All but 5 patients lived in seven buildings (A to G), and the index patient and more than half the other patients with SARS (99 patients) lived in building E. Residents of the floors at the middle and upper levels in building E were at a significantly higher risk than residents on lower floors; this finding is consistent with a rising plume of contaminated warm air in the air shaft generated from a middle-level apartment unit. The risks for the different units matched the virus concentrations predicted with the use of multizone modeling. The distribution of risk in buildings B, C, and D corresponded well with the three-dimensional spread of virus-laden aerosols predicted with the use of computational fluiddynamics modeling. conclusions Airborne spread of the virus appears to explain this large community outbreak of SARS, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus.

1,106 citations

Journal ArticleDOI
TL;DR: Practice of droplets precaution and contact precaution is adequate in significantly reducing the risk of infection after exposures to patients with SARS.

780 citations

Journal ArticleDOI
TL;DR: Extensive evidence indicates that aerosol transmission of influenza occurs and should be taken into account for pandemic planning.
Abstract: In theory, influenza viruses can be transmitted through aerosols, large droplets, or direct contact with secretions (or fomites). These 3 modes are not mutually exclusive. Published findings that support the occurrence of aerosol transmission were reviewed to assess the importance of this mode of transmission. Published evidence indicates that aerosol transmission of influenza can be an important mode of transmission, which has obvious implications for pandemic influenza planning and in particular for recommendations about the use of N95 respirators as part of personal protective equipment.

766 citations


"Evaluation of droplet dispersion du..." refers methods in this paper

  • ...Those who were using NIV received 20 minutes of ventilatory support at their current clinically indicated IPAP and EPAP settings, with oxygen entrained to maintain saturation to > 90%, first with the modified circuit and non-vented mask (2) and secondly with the vented face mask (1)....

    [...]

  • ...NIV was delivered (1) using a vented full-face mask that was sized to subject (ResMed vented hospital-use face mask) or (2) using a modified circuit....

    [...]

  • ...Methods: Three groups were studied: (1) normal controls, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation....

    [...]

  • ...Three groups were studied: (1) normal control subjects, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation....

    [...]

Journal ArticleDOI
16 Jul 2008-PLOS ONE
TL;DR: Findings regarding influenza virus RNA suggest that influenza virus may be contained in fine particles generated during tidal breathing, and add to the body of literature suggesting that fine particle aerosols may play a role in influenza transmission.
Abstract: Background Recent studies suggest that humans exhale fine particles during tidal breathing but little is known of their composition, particularly during infection.

481 citations


"Evaluation of droplet dispersion du..." refers methods in this paper

  • ...Those who were using NIV received 20 minutes of ventilatory support at their current clinically indicated IPAP and EPAP settings, with oxygen entrained to maintain saturation to > 90%, first with the modified circuit and non-vented mask (2) and secondly with the vented face mask (1)....

    [...]

  • ...NIV was delivered (1) using a vented full-face mask that was sized to subject (ResMed vented hospital-use face mask) or (2) using a modified circuit....

    [...]

  • ...Methods: Three groups were studied: (1) normal controls, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation....

    [...]

  • ...Three groups were studied: (1) normal control subjects, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation....

    [...]

Journal Article
TL;DR: Evidence to date suggests that SARS is a severe respiratory illness spread mainly by respiratory droplets, and there has been no evidence of further transmission within the hospital after the elapse of 2 full incubation periods.
Abstract: Background: Severe acute respiratory syndrome (SARS) was introduced into Canada by a visitor to Hong Kong who returned to Toronto on Feb. 23, 2003. Transmission to a family member who was later admitted to a community hospital in Toronto led to a large nosocomial outbreak. In this report we summarize the preliminary results of the epidemiological investigation into the transmission of SARS between 128 cases associated with this hospital outbreak. Methods: We collected epidemiologic data on 128 probable and suspect cases of SARS associated with the hospital outbreak, including those who became infected in hospital and the next generation of illness arising among their contacts. Incubation periods were calculated based on cases with a single known exposure. Transmission chains from the index family to hospital contacts and within the hospital were mapped. Attack rates were calculated for nurses in 3 hospital wards where transmission occurred. Results: The cases ranged in age from 21 months to 86 years; 60.2% were female. Seventeen deaths were reported (case-fatality rate 13.3%). Of the identified cases, 36.7% were hospital staff. Other cases were household or social contacts of SARS cases (29.6%), hospital patients (14.1%), visitors (14.1%) or other health care workers (5.5%). Of the 128 cases, 120 (93.8%) had documented contact with a SARS case or with a ward where there was a known SARS case. The remaining 8 cases without documented exposure are believed to have had exposure to an unidentified case and remain under investigation. The attack rates among nurses who worked in the emergency department, intensive care unit and coronary care unit ranged from 10.3% to 60.0%. Based on 42 of the 128 cases with a single known contact with a SARS case, the mean incubation period was 5 days (range 2 to 10 days). Interpretation: Evidence to date suggests that SARS is a severe respiratory illness spread mainly by respiratory droplets. There has been no evidence of further transmission within the hospital after the elapse of 2 full incubation periods (20 days).

359 citations

Related Papers (5)