Infection control in mass respiratory failure: preparing to respond to H1N1

Risk of Transmitting Coronavirus Disease 2019 During Nebulizer Treatment: A Systematic Review

Rationale: There is an urgent need to understand the risk of viral transmission during nebulizer treatment of patients with coronavirus disease 2019 (COVID-19). Objectives: To assess the risk of transmitting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), SARS, Middle East respiratory syndrome (MERS), and influenza with administration of drugs via nebulizer. Methods: We searched multiple electronic databases, including PubMed^®, China National Knowledge Infrastructure, Wanfang, preprint databases, and clinicaltrials.gov through December 1, 2020. Any study design in any language describing the risk of viral transmission with nebulizer treatment was eligible. Data were abstracted by one investigator and verified by a second. Results: We identified 22 articles: 1 systematic review, 7 cohort/case-control studies, 7 case series, and 7 simulation-based studies. Eight individual studies involved patients with SARS, five involved MERS, and one involved SARS-CoV-2. The seven cohort/case-control studies (four high risk of bias [ROB], three unclear ROB) found mixed results (median odds ratio 3.91, range 0.08-20.67) based on very weak data among a small number of health care workers (HCWs) with variable use of personal protective equipment (PPE). Case series had multiple potential contributors to transmission. Simulation studies found evidence for droplet dispersion after saline nebulization and measureable influenza viral particles up to 1.7 m from the source after 10 minutes of nebulization with a patient simulator. Study heterogeneity prevented meta-analysis. Conclusions: Case series raise concern of transmission risk, and simulation studies demonstrate droplet dispersion with virus recovery, but specific evidence that exposure to nebulizer treatment increases transmission of coronaviruses similar to COVID-19 is inconclusive. Tradeoffs balancing HCW safety and patient appropriateness can potentially minimize risk, including choice of delivery method for inhaled medications (e.g., nebulizer vs. metered dose inhaler) and PPE (e.g., N95 vs. surgical mask).

Bacterial and viral contamination of breathing circuits after extended use - an aspect of patient safety?

BACKGROUND

In the past, anaesthetic breathing circuits were identified as a source of pathogen transmission. It is still debated, whether breathing circuits combined with breathing system filters can be safely used for more than 1 day. The aim of this study was to evaluate the transmission risk of bacteria and also viruses via breathing circuits after extended use.

METHODS

The inner and outer surface of 102 breathing circuits used for 1 day and of 101 circuits used for 7 days were examined for bacteria and viruses. Additionally, 10 and 20 breathing circuits each were examined after use on patients with pulmonary virus infection and with multidrug-resistant organism (MDRO) colonisation/infection respectively. Bacteria were detected by standard microbiological procedures; PCR techniques were applied for herpes simplex virus, cytomegalovirus, influenza, parainfluenza and respiratory syncytial virus.

RESULTS

Endoluminal bacterial contamination of breathing circuits remained unchanged after 7-day vs. 1-day use (5.9% vs. 7.8%) [CI95%: -0.0886-0.0506, pnon-inferiority 0.0260]. Only outside surface contamination with bacteria belonging to environmental species or human flora increased (16.8 vs. 6.9%) [CI 95%: 0.0118 - 0.1876, pnon-inferiority 0.8660]. Viruses occurred on the patient side, but not in breathing circuits. No MDRO occurred in the 20 circuits after use on patients harbouring such germs.

CONCLUSION

Endoluminal contamination of breathing circuits with bacteria did not increase after extended use. No viruses were detected in the breathing circuits using filters. Based on our results, the extended use of ABC without exceptions appears safe, if a high level of anaesthesia workplace cleaning is secured.

Wireless integrated biosensors for point-of-care diagnostic applications

Recent advances in integrated biosensors, wireless communication and power harvesting techniques are enticing researchers into spawning a new breed of point-of-care (POC) diagnostic devices that have attracted significant interest from industry. Among these, it is the ones equipped with wireless capabilities that drew our attention in this review paper. Indeed, wireless POC devices offer a great advantage, that of the possibility of exerting continuous monitoring of biologically relevant parameters, metabolites and other bio-molecules, relevant to the management of various morbid diseases such as diabetes, brain cancer, ischemia, and Alzheimer's. In this review paper, we examine three major categories of miniaturized integrated devices, namely; the implantable Wireless Bio-Sensors (WBSs), the wearable WBSs and the handheld WBSs. In practice, despite the aforesaid progress made in developing wireless platforms, early detection of health imbalances remains a grand challenge from both the technological and the medical points of view. This paper addresses such challenges and reports the state-of-the-art in this interdisciplinary field.

Preparing ICUs for pandemics

PURPOSE OF REVIEW

Influenza pandemics occur intermittently and represent an existential global infectious diseases threat. The purpose of this review is to describe clinical and research preparedness for future pandemics.

RECENT FINDINGS

Pandemic influenza typically results in large numbers of individuals with life-threatening pneumonia requiring treatment in ICUs. Clinical preparedness of ICUs relates to planning to provide increased 'surge' capacity to meet increased demand and requires consideration of staffing, equipment and consumables, bed-space availability and management systems. Research preparedness is also necessary, as timely clinical research has the potential to change the trajectory of a pandemic. The clinical research response during the 2009 H1N1 influenza pandemic was suboptimal.

SUMMARY

Better planning is necessary to optimize both clinical and research responses to future pandemics.

Respiratory and facial protection: a critical review of recent literature

Infectious micro-organisms may be transmitted by a variety of routes. This is dependent on the particular pathogen and includes bloodborne, droplet, airborne, and contact transmission. Some micro-organisms are spread by more than one route. Respiratory and facial protection is required for those organisms which are usually transmitted via the droplet and/or airborne routes or when airborne particles have been created during 'aerosol-generating procedures'. This article presents a critical review of the recently published literature in this area that was undertaken by Health Protection Scotland and the Healthcare Infection Society and which informed the development of guidance on the use of respiratory and facial protection equipment by healthcare workers.

Characteristics and outcome of mechanically ventilated patients with 2009 H1N1 influenza in Bosnia and Herzegovina and Serbia: impact of newly established multidisciplinary intensive care units

Aim

To describe characteristics and outcome of mechanically ventilated patients admitted to three newly established intensive care units (ICU) in Bosnia-Herzegovina and Serbia for 2009 H1N1 influenza infection.

Methods

The retrospective observational study included all mechanically ventilated adult patients of three university-affiliated hospitals between November 1^, 2009 and March 1 2010 who had 2009 H1N1 influenza infection confirmed by real-time reverse transcriptase-polymerase-chain-reaction (RT-PCR) from nasopharyngeal swab specimens and respiratory secretions.

Results

The study included 50 patients, 31 male (62%), aged 43 ± 13 years. Median time from hospital to ICU admission was 1 day (range 1-2). Sixteen patients (30%) presented with one or more chronic medical condition: 8 (16%) with chronic lung disease, 5 (10%) with chronic heart failure, and 3 (6%) with diabetes mellitus. Thirty-two (64%) were obese. Forty-eight patients (96%) experienced acute respiratory distress syndrome (ARDS), 28 (56%) septic shock, and 27 (54%) multiorgan failure. Forty-five patients (90%) were intubated and mechanically ventilated, 5 received non-invasive mechanical ventilation, 7 (14%) high-frequency oscillatory ventilation, and 7 (14%) renal replacement therapy. The median duration of mechanical ventilation was 7 (4-14) days. Hospital mortality was 52%.

Effectiveness of surgical masks against influenza bioaerosols

BACKGROUND

Most surgical masks are not certified for use as respiratory protective devices (RPDs). In the event of an influenza pandemic, logistical and practical implications such as storage and fit testing will restrict the use of RPDs to certain high-risk procedures that are likely to generate large amounts of infectious bioaerosols. Studies have shown that in such circumstances increased numbers of surgical masks are worn, but the protection afforded to the wearer by a surgical mask against infectious aerosols is not well understood.

AIM

To develop and apply a method for assessing the protection afforded by surgical masks against a bioaerosol challenge.

METHODS

A dummy test head attached to a breathing simulator was used to test the performance of surgical masks against a viral challenge. Several designs of surgical masks commonly used in the UK healthcare sector were evaluated by measuring levels of inert particles and live aerosolised influenza virus in the air, from in front of and behind each mask.

FINDINGS

Live influenza virus was measurable from the air behind all surgical masks tested. The data indicate that a surgical mask will reduce exposure to aerosolised infectious influenza virus; reductions ranged from 1.1- to 55-fold (average 6-fold), depending on the design of the mask.

CONCLUSION

We describe a workable method to evaluate the protective efficacy of surgical masks and RPDs against a relevant aerosolised biological challenge. The results demonstrated limitations of surgical masks in this context, although they are to some extent protective.

Two years after pandemic influenza A/2009/H1N1: what have we learned?

The world had been anticipating another influenza pandemic since the last one in 1968. The pandemic influenza A H1N1 2009 virus (A/2009/H1N1) finally arrived, causing the first pandemic influenza of the new millennium, which has affected over 214 countries and caused over 18,449 deaths. Because of the persistent threat from the A/H5N1 virus since 1997 and the outbreak of the severe acute respiratory syndrome (SARS) coronavirus in 2003, medical and scientific communities have been more prepared in mindset and infrastructure. This preparedness has allowed for rapid and effective research on the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the disease, with impacts on its control. A PubMed search using the keywords "pandemic influenza virus H1N1 2009" yielded over 2,500 publications, which markedly exceeded the number published on previous pandemics. Only representative works with relevance to clinical microbiology and infectious diseases are reviewed in this article. A significant increase in the understanding of this virus and the disease within such a short amount of time has allowed for the timely development of diagnostic tests, treatments, and preventive measures. These findings could prove useful for future randomized controlled clinical trials and the epidemiological control of future pandemics.

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients

Heat and moisture exchangers and breathing system filters are intended to replace the normal warming, humidifying and filtering functions of the upper airways. The first part of this review considered the history, principles of operation and efficiency of these devices. The aim of this part of the review is to summarise recent guidelines on the use of these devices and outline the problems that can occur. In particular, the effect of these devices on gas analysis, dead space, resistance to gas flow and blockage of the breathing system is considered. In children, it is important to consider the addition of dead space and resistance to gas flow. A body weight of 2.5 kg is probably the lower weight limit for use with heat and moisture exchangers, and 3 kg for filters. The resistance to gas flow of a heat- and moisture-exchanging filter added to a Mapleson F breathing system can cause a delay in the induction of anaesthesia.