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Here, we present a protocol for determining the bacterial filtration efficiencies of facemask materials according to the American Society for Testing and Materials (ASTM) standard F2101-19. We describe steps for reproducibly generating, collecting, and enumerating viable bacteria-laden aerosols containing the bacterial pathogen Staphylococcus aureus. The optimized operating parameters generate 1,700 to 3,000 viable bacteria-laden aerosol droplets between 2.7 and 3.3 μm.

AbstractRATIONALE: Dyspnea and respiratory impairment are sequelae of COVID-19.OBJECTIVESThe objectives of this study were to observe the prevalence and clinical relevance of ventilation (V) and perfusion (Q) impairment, evaluated by ventilation/perfusion-single-photon emission computed tomography-computed tomography (VQ-SPECT-CT), in individuals with no history of lung disease 4-weeks after recovery from noncritical COVID-19.METHODSWe enrolled 25 COVID-19 patients’ post-recovery and 11 control subjects. All participants underwent VQ-SPECT-CT using 99mTc-Technegas for V and 99mTc-macroaggregated albumin for Q, spirometry, six-minute-walk-test, blood draw and completed the modified Medical Research Council (mMRC) dyspnea-scale and St. Georges Respiratory Questionnaire (SGRQ). VQ-SPECT-CT was reviewed to report lung function and structure abnormalities and ventilation-heterogeneity was quantified to evaluate associations with symptoms, exercise-capacity and inflammatory markers.MEASUREMENTS AND MAIN RESULTS: Of 25 post-COVID-19 participants, 9 were hospitalized and 16 home-isolated during acute-infection. A total of 88% of hospitalized and 44% of home-isolated participants were reported to have V defects (matched VQ defects: 63% and 44%; mismatched V defects: 38% and 13%), compared to 30% of never-COVID-19 controls (matched VQ defects: 30%, mismatched V defects: 10%) (P = 0.02 and P = 0.68, respectively). Ventilation-heterogeneity was greater in hospitalized (P = 0.003), but not home-isolated participants, compared to the never-COVID-19 controls. Post-COVID-19 ventilation-heterogeneity correlated with the dyspnea-scale (r = 0.45, P = 0.03), SGRQ-score (r = 0.41, P = 0.04), 6MWD (r=-0.49, P = 0.02), SpO2 (P = -0.55, P = 0.005), CT parenchymal opacities (r = 0.42, P = 0.04) and neutrophil percent (r = 0.45, P = 0.04), but not pro-inflammatory cytokines, C-reactive protein or D-dimer.CONCLUSIONSThis small functional lung imaging study revealed ventilation impairment in individuals with no history of lung disease recovering from noncritical COVID-19 that was associated with parenchymal opacities, respiratory symptoms and exercise-capacity.

Management of the global crisis of the coronavirus disease 2019 pandemic requires detailed appraisal of evidence to support clear, actionable, and consistent public health messaging. The use of cloth masks for general public use is being debated, and is in flux. We searched the MEDLINE and EMBASE databases and Google for articles reporting the filtration properties of flat cloth or cloth masks. We reviewed the reference lists of relevant articles to identify further articles and identified articles through social and conventional news media. We found 25 articles. Study of protection for the wearer used healthy volunteers, or used a manikin wearing a mask, with airflow to simulate different breathing rates. Studies of protection of the environment, also known as source control, used convenience samples of healthy volunteers. The design and execution of the studies was generally rigorously described. Many descriptions of cloth lacked the detail required for reproducibility; no study provided all the expected details of material, thread count, weave, and weight. Some of the homemade mask designs were reproducible. Successful masks were made of muslin at 100 threads per inch (TPI) in 3 to 4 layers (4-layer muslin or a muslin-flannel-muslin sandwich), tea towels (also known as dish towels), made using 1 layer (2 layers would be expected to be better), and good-quality cotton T-shirts in 2 layers (with a stitched edge to prevent stretching). In flat-cloth experiments, linen tea towels, 600-TPI cotton in 2 layers, and 600-TPI cotton with 90-TPI flannel performed well but 80-TPI cotton in 2 layers did not. We therefore recommend cotton or flannel at least 100 TPI, at least 2 layers. More layers, 3 or 4, will provide increased filtration but there is a trade-off in that more layers increases the resistance to breathing. Although this is not a systematic review, we included all the articles that we identified in an unbiased way. We did not include gray literature or preprints. A plain language summary of these data and recommendations, as well as information on making, wearing and cleaning cloth masks is available at www.clothmasks.ca.

Inefficient inhaler technique (IT) compromises the optimal delivery of medication. However, the IT knowledge of health care professionals (HCPs) has received scant attention.

Aerosolised drugs are prescribed for use in a range of inhaler devices and systems. Delivering drugs by inhalation requires a formulation that can be successfully aerosolised and a delivery system that produces a useful aerosol of the drug; the particles or droplets need to be of sufficient size and mass to be carried to the distal lung or deposited on proximal airways to give rise to a therapeutic effect. Patients and caregivers must use and maintain these aerosol drug delivery devices correctly. In recent years, several technical innovations have led to aerosol drug delivery devices with efficient drug delivery and with novel features that take into account factors such as dose tracking, portability, materials of manufacture, breath actuation, the interface with the patient, combination therapies, and systemic delivery. These changes have improved performance in all four categories of devices: metered dose inhalers, spacers and holding chambers, dry powder inhalers, and nebulisers. Additionally, several therapies usually given by injection are now prescribed as aerosols for use in a range of drug delivery devices. In this Review, we discuss recent developments in the design and clinical use of aerosol devices over the past 10–15 years with an emphasis on the treatment of respiratory disorders.

In vivo aerosol delivery efficiency was estimated in vitro for two jet nebulizers using a breath monitor (Breathe!; Pari GmbH, Germany) and breath simulator (COMPAS®; Pari GmbH) to reproduce subject tidal breathing patterns. The AeroEclipse (Trudell Medical International, Canada), a breath-actuated nebulizer, and the LC Star (Pari GmbH), a breath-enhanced nebulizer, were filled with levalbuterol HCl solution (Sepracor, USA) and operated with compressed O2 at 8 lpm. Tidal breathing patterns of 20 adult subjects were digitally recorded with the Breathe! Breath Monitor. Subjects then breathed tidally from each nebulizer separately for 1 minute and to nebulizer dryness. Levalbuterol aerosol collected on filters placed between the nebulizer and mouth was chemically assayed to determine the inspired mass (IM), wasted mass (WM) and total emitted mass (TM). Measurements were repeated using the COMPAS® Breath Simulator to simulate each subject's tidal breathing pattern. IM, WM, and TM measurements using actual versus simulated tidal breathing were highly comparable for each nebulizer, except the IM (p < 0.05) from LC Star measured at nebulizer dryness. Breath simulation was an inaccurate tool for estimating the time to nebulizer dryness as simulated measurements to nebulizer dryness took significantly longer than measurements preformed with actual tidal breathing (p < 0.001). While breath simulation provides an accurate in vitro tool for estimating in vivo aerosol delivery, it should not completely replace in vivo measurements until inherent limitations in simulator operation can be overcome to provide a more clinically realistic simulation.

The proliferation of inhaler devices has resulted in a confusing number of choices for clinicians who are selecting a delivery device for aerosol therapy. There are advantages and disadvantages associated with each device category. Evidence-based guidelines for the selection of the appropriate aerosol delivery device in specific clinical settings are needed.

What is the relative per microgram potency and side effect profile of the β-agonists salbutamol and fenoterol?

Nasal epithelial (NE) cells were collected from the nasopharynx of 25 individuals with symptomatic colds and 27 healthy volunteers (controls), and ciliary beat frequency (CBF) was assessed by microscopy employing video motion analysis techniques. Baseline CBF was statistically significantly elevated in the group with colds compared to the control group (14.6± 1.5 Hz [mean±SD] vs 13.8±0.9 Hz; p = 0.02). After four days of incubation in culture, there was a significant decrease in the CBF in both groups, with a change from baseline of 1.9 Hz for the cold group, compared to 1.0 Hz for the control group (p = 0.0001). The in vitroaddition of ribavirin at 500μg/ml to NE cells from individuals with colds preserved the viability of the cells and maintained the CBF at baseline values. Twenty-four (96 percent) of 25 ribavirin-treated specimens from the cold group survived for four days in culture, compared with 17 (68 percent) of 25 untreated cold specimens. In addition, the ribavirin-treated cells had a mean CBF of 14.2 ±1.3 Hz, compared with 12.7 ±1.9 Hz for the untreated cell samples (p = 0.0005). Ribavirin had no effect on NE cells from the control group. These results suggest that ribavirin in a concentration of 500μg/ml may have some benefit in the treatment of acute rhinorrhea. (Chest 1992; 102:284–87)

Measurements of mucociliary clearance and lung epithelial permeability are relatively simple to perform, with minimum discomfort to the subjects. Awareness of the factors influencing the outcome of these procedures will help to avoid errors and yield useful information about these two clearance mechanisms from both a physiological and a pathological point of view.

To compare aerosol delivery to the lungs in ventilated patients from two devices with holding chamber and two devices without holding chamber.

Patients with asthma and elevated blood eosinophils are at increased risk of severe exacerbations. Management of these patients should consider nonadherence to inhaled corticosteroid (ICS) therapy as a factor for increased exacerbation risk.

Spacers are often used with pressurized metered-dose inhalers (pMDIs) to eliminate the need for coordinating inhalation with actuation.

Studies were performed to detect a possible in vivo effect of the ciliary dyskinesia factor of cystic fibrosis (CF) serum. Following application of serum to the nasal mucosa of CF patients and normal subjects, nasal mucociliary clearance (MCC) was assessed by a radioisotope technique. Removal of a radioactive droplet applied to the mucocutaneous junction of the nose was quantified by means of an Anger scintillation camera interfaced to a data storage and retrieval system. Autologous serum applied to the nasal mucosa failed to inhibit MCC in normals or in CF patients, nor did CF serum inhibit MCC in normals. By contrast, an inflammatory response induced by locally applied anti-serum to human IgE retarded MCC in CF patients but not in normals: it is presumed that the local effect of anti-IgE on MCC in CF was the result of an exudation of the serum dyskinesia factor. Possibly, recurrent or persistent pulmonary infection In CF relates to a local exudation of this factor, hindering effective clearance of secretions.Supported by C.F. Foundation, MRC (Canada), Ont. Thoracic Soc., Can. TB & RD Soc.

Technetium-99m labelled Salbutamol was administered through a tracheostomy to ventilated rabbits by either an MDI (5 puffs,100µg/puff) aided with a spacer (MV15 Aerochamber, Trudell, Canada) (Group1, n=7); or by nebulization (100µig/kg in 3ml Technetium-99m labelled 5% albumin). Nebulization was carried out for 20 min. with a Jet (Hudson, USA) (Group 2, n=11)or Ultrasonic device (Siemens, Sweden) using either a standard (Group 3, n=6) or a small (Group 4, n=7) reservoir. Lung deposition was estimated by gamma counting of the autopsy lung specimens: mean(sd):Salbutamol was uniformly distributed in the lungs in group 1 and 2, but showed a predilection for the right anterior azygous lobes and the central lung regions in group 3 and 4.Conclusion: in delivering Salbutamol to ventilated rabbits, this Ultrasonic device provides greater lung deposition but less uniform distribution than either Jet or MDI. Reducing reservoir volume enhances its efficiency of delivery further, but also yields differential deposition in lobes.