Proposal of a Mask and Its Performance Analysis with CFD for an Enhanced Aerodynamic Geometry That Facilitates Filtering and Breathing against COVID-19

As a result of the recent events associated with the SARS-CoV-2 around the world, there has been a need for research to strengthen health care. The use of masks or respirators has been an effective measure, reducing the risk of contagion caused by the spread of the virus in public places. Currently, there are masks that retain up to 99% of particles >0.3 microns; however, they lack an airtight seal with the face, leading to discomfort and poor protection in conditions without social distancing and areas without ventilation. The device proposed in this study includes a geometric design of static valves with convergent spirals and interior baffles that promotes enhanced aerodynamics with bidirectional flow. According to the analysis and CFD simulation of the proposed reusable, washable, and economic mask and valve system for breathing, coughing, and sneezing events, enhanced air exchange could be maintained, facilitating a higher inhalation flow through the side of the mask (62%) and a higher exhalation through the front of the mask (74%), thereby avoiding the recirculation of the flow to the interior of the mask. The inclusion of filters with KN95 characteristics in the inlets and outlets maintains velocities below 10 cm/s, reducing the probability of infection.

Reliability and Characterization of Micro-Packages in a Wafer Level Au-Si Eutectic Vacuum Bonding Process

A Au-Si eutectic vacuum packaging process was evaluated using high sensitivity poly-Si Pirani vacuum sensors. Encapsulation of devices was achieved by bonding a silicon cap wafer to a device wafer using a Au-Si eutectic solder at above 390°C in a vacuum bonder. The Au-Si eutectic solder encircled the devices, providing an airtight seal. The Pirani gauges were encapsulated and tested over a period of several months in order to determine base pressures and leak/outgassing rates of the micro-cavities. Packaged devices without getters showed initial pressures from 2 to 12 Torr with initial leak/outgassing rates of −0.073 to 80 Torr/year. Using getters, pressures as low as 5 mTorr have been achieved with leak/outgassing rates of <10 mTorr/year. Trends in pressure over time seem to indicate outgassing (desorption of atoms from inside of the microcavity) as the primary mechanism for pressure change over time.

Reinforcement of an end-to-end Tracheal Resection Anastomosis with Fibrin Glue: A Case Report

Tracheal resection and primary anastomosis is the treatment of choice for a short-segment stenosis. However, the procedure does carry the risk of two potentially fatal complications: anastomosis breakdown and leak. We describe the case of a 67-year-old man who was treated for a 3-cm tracheal stenosis secondary to a prolonged intubation and multiple tracheostomies. The patient underwent a tracheal resection and primary anastomosis. The anastomosis was reinforced with fibrin sealant, which created an airtight seal. The patient was extubated postoperatively, and he healed without complication. Fibrin sealant is a convenient, safe, and effective material for reinforcing anastomotic suture lines.

An Evaluation of Hospital Special-Ventilation-Room Pressures

Objective:To quantitate the magnitude and consistency of positive (airflow out) and negative (airflow in) hospital special-ventilation-room (SVR) airflow.Design:A room-pressure evaluation was conducted during two seasons on a total of 18 rooms: standard rooms, airborne infection isolation rooms, and protective environment rooms. The pressures were measured using a digital pressure gaugepiezoresistive pressure sensor that measured pressure differentials. With doors closed, the rooms were measured a minimum of 30 times each for a cooling season and a heating season.Results:The standard rooms showed the least amount of variability in pressure differential, with an average of −0.2 Pa (median, −0.2 Pa), and an interquartile range (IQR) of 0.4 Pa. Airborne infection isolation rooms showed more variability in pressure, with an average of −0.3 Pa (median, −0.2 Pa) and an IQR of 0.5 Pa. Protective environment rooms had the greatest fluctuation in pressure, with an average of 8.3 Pa (median, 7.7 Pa) and an IQR of 8.8 Pa. Dramatic pressure changes were observed during this evaluation, which may have been influenced by room architectural differences (sealed vs unsealed); heating, ventilation, and air-conditioning zone interactions; and stack effect.Conclusion:The pressure variations noted in this study, which potentially affect containment or exclusion of contaminants, support the need for standardization of pressure requirements for SVRs. To maintain consistent pressure levels, creating an airtight seal and continuous pressure monitoring may be necessary.

A homemade modification of a spacer device for delivery of bronchodilator or steroid therapy in patients with tracheostomies

Patients who have artificial airways and who concurrently suffer with chronic obstructive airways disease encounter problems when administering inhaled bronchodilator and corticosteroid drugs via the tracheostomy. This is because most of the devices are designed to deliver the metered dose of inhaled drugs via the oropharyngeal route and it is impossible to obtain an airtight seal from the inhaler device mouthpiece to the tracheostomy tube. The author describes a simple, effective and cheap modification of a spacer device designed by a creative patient to facilitate delivery of the aerosol via the tracheostomy tube to overcome this problem.

Letters to Editor

We are pleased indeed that others have found the simplified technique for tympanocentesis that we reported helpful in pediatric practice. The authors of the letter above asked whether we feel that a filter and adapter are necessary since they have found a specific rubber tubing that can provide an airtight seal without the need of an adapter and filter. We feel that the modification of our technique described by the authors is quite acceptable but would prefer the filter element if possible since it prevents contamination of material aspirated into the syringe by saliva contributed by the physician-operator.