VI. Equipment and Potential Modification

November 8, 2021

• Elastomeric Respirators for COVID-19 and the Next Respiratory Virus Pandemic: Essential Design Elements. 10/19/21. Bowdle TA. Anesthesiology.
  Although healthcare workers have relied primarily on disposable filtering facepiece respirators (such as N95) during the COVID-19 pandemic, reusable elastomeric respirators (typically used for industrial purposes) have potential advantages for the COVID-19 and future respiratory virus pandemics. These advantages include improved fit, better inspiratory filtration and less waste. However, currently available elastomeric respirators were not designed primarily for healthcare or pandemic use and require further development to improve their suitability for this application. This article explores the advantages of elastomeric respirators, and the adaptations needed (such as eliminating the expiratory valve) to make them useful for healthcare providers. Table 1 (Respiratory Protection Terminology) and good photos provide an excellent background for understanding respirators.

December 16, 2020

• Decontamination and Reuse of N95 Filtering Facepiece Respirators: Where Do We Stand? 12/15/20. Cassorla L. Anesth Analg.
  Interest in decontamination methods for N95 respirators increased during the COVID-19 pandemic along with shortages and altered practices in health care facilities. This is a well-referenced review of available science. Best-supported methods are based upon time, heat, microwave-generated steam, hydrogen peroxide, or UV-C (ultraviolet germicidal irradiation, UVGI). Many require special equipment and most require procedures to prevent cross-contamination and return each respirator to its original user due to the potential for residual organisms other than SARS-CoV-2. Tables include reference websites, a summary of methods, and current FDA emergency use authorizations.

October 7, 2020

• Portable pocket-sized ultrasound scanner for the evaluation of lung involvement in COVID-19 patients. 9/21/20. Bennett D. Ultrasound in Medicine & Biology.
  No significant differences were found between lung ultrasound scores obtained with a high-end or a portable pocket-sized ultrasound scanner on 437 paired readings in 34 LUS evaluations of hospitalized patients, including patients with mild (n=7), moderate (n=11) and severe (n=16) disease. The tested pocket-sized scanner has a single silicon chip containing a 2D array of 9000 capacitive micromachined ultrasound transducers instead of the standard piezoelectric crystal-based transducers. The chip emulates curved, linear, or phased transducers in M-mode, B-mode or color Doppler with a 2–30 cm scan depth.

September 25, 2020

• Association of Daily Wear of Eyeglasses With Susceptibility to Coronavirus Disease 2019 Infection. 9/16/20. Zeng W. JAMA Ophthalmol.
  While the public has not received guidance to wear eye protection to decrease the risk of COVID-19, Zeng raised the question of whether ordinary eyeglasses may help prevent infection, as in their observational study of 276 COVID-19 inpatients of which only 5.8% wore glasses vs. 31.5% in a reference population. This editorial highlights the study’s weaknesses, including that the “local population” data were from another region of China and another time period altogether. Although the data are unlikely to be by chance alone, an inference of cause requires additional study.

July 15, 2020

• Differential Ventilation Using Flow Control Valves as a Potential Bridge to Full Ventilatory Support during the COVID-19 Crisis: From Bench to Bedside. 7/2/20. Levin MA. Anesthesiology.
  Review by the SAB
  By Dr. Lance Lichtor, on behalf of the SAB
  Proof of concept: single ventilator with split circuit. The author could increase one patient’s minute ventilation without affecting the other patient. Effective use for a crisis situation. The authors used custom-designed and manufactured flow control valves.

June 29, 2020

• Ventilator Sharing During an Acute Shortage Caused by the COVID-19 Pandemic. June 9. Beitler JR. Am J Respir Crit Care Med.
  Detailed report discussing a 2 patient on one ventilator sharing strategy, with results and lessons learned from 3 pairs of patients with COVID-19 ARDS at NY-Presbyterian/Columbia University Irving Medical Center who shared ventilators for 2 days without adverse events.
  • Pre-specified criteria shown in Table 1 were used to identify compatible patient pairs.
  • Minimizing between-patient driving pressure differences was prioritized.
  • Deep sedation and neuromuscular blockade were maintained.
  • Ventilators were set to pressure-control.
  • After determining average identical ventilator settings while on separate machines, patients were transitioned to a shared ventilator with the same settings.
  • An unused rescue ventilator was available.
  • Single patient ventilators are needed for weaning and individualized support.
  • ICU ventilators are superior to anesthesia machines for sharing.
  • Multiple antimicrobial filters and matching by pathogen decreases risk of sharing infection.
  • Frequent changing of CO2 absorbent and heat moisture exchange filters was needed.

  Since the safety and utility of sharing > 48 hours is not known, the authors suggest that ventilator sharing is most reasonable as a stopgap to allow relocating of ventilators or patients to meet demand.

June 15, 2020

• Ventilator Sharing During an Acute Shortage Caused by the COVID-19 Pandemic. June 9. Beitler JR. Am J Respir Crit Care Med.
  Detailed report discussing a 2 patient on one ventilator sharing strategy, with results and lessons learned from 3 pairs of patients with COVID-19 ARDS at NY-Presbyterian/Columbia University Irving Medical Center who shared ventilators for 2 days without adverse events.
  • Pre-specified criteria shown in Table 1 were used to identify compatible patient pairs.
  • Minimizing between-patient driving pressure differences was prioritized.
  • Deep sedation and neuromuscular blockade were maintained.
  • Ventilators were set to pressure-control.
  • After determining average identical ventilator settings while on separate machines, patients were transitioned to a shared ventilator with the same settings.
  • An unused rescue ventilator was available.
  • Single patient ventilators are needed for weaning and individualized support.
  • ICU ventilators are superior to anesthesia machines for sharing.
  • Multiple antimicrobial filters and matching by pathogen decreases risk of sharing infection.
  • Frequent changing of CO2 absorbent and heat moisture exchange filters was needed.

  Since the safety and utility of sharing > 48 hours is not known, the authors suggest that ventilator sharing is most reasonable as a stopgap to allow relocating of ventilators or patients to meet demand.

June 9, 2020

• Effectiveness of N95 Respirator Decontamination and Reuse against SARS-CoV-2 Virus
  June 3. Fischer RJ. Emerging Infectious Diseases.
  Opinion from SAB Member: Dr. Lydia Cassorla
  Using SARS-CoV-2, this study sponsored by the US government builds on the knowledge needed to evaluate the efficacy of decontamination methods that are being used around the world to extend the life of N95 masks due to shortages of new masks. N95 fabric discs and some whole masks were studied following treatments with ethanol, vaporized hydrogen peroxide (VHP), UV-C irradiation (UVGI), and dry heat. Data was modeled and extrapolated to calculate expected 3-log (threshold considered decontamination) and 6-log (threshold considered sterilization) reductions in viral load. For 3-log reduction, dry heat at 70°C took 46.3 min and UVGI took a dose of 2J/cm2, delivered to one side only. SARS-CoV-2 virus was undetectable after the initial treatment time for VHP, so no modeling was done. Mask fit and filtration performance was tested on 6 whole N95 masks per method for 3 cycles using a quantitative fit test that results in a fit score. Mask fit and filter function (tested in 6 masks/method after wearing for 2 hours) was good following 3 cycles of VHP and UVGI, but began to decline following the 3rd cycle of heat (note: their conditions were drier than some recommend). While ethanol sterilized well, it caused mask function failure and is not recommended. Control data with no treatment showed a median viral half-life of 78.5 min at 21-23°C with 40% relative humidity and a calculated 3-log reduction in 13 hrs. Despite limitations, this work adds important data regarding SARS-CoV-2 viability on N95 fabric along with measures of N95 fit and function under control and after test conditions. VHP provided the best combination of effectiveness and speed with good retention of fit and filtration function for 3 cycles (all that was tested) but requires proprietary equipment (note, some companies providing VHP equipment have received Emergency Use Authorizations from the FDA during the pandemic). UVGI and heat require care to take the time required to achieve the desired reduction in viral load and ensure procedures are followed to prevent cross-contamination, as they are not necessarily sterilizing techniques. Readers will also find data regarding stainless steel surfaces (not discussed in this summary). The CDC continues to provide some guidance regarding this issue on its website, where the publication is currently posted in pre-print form.

May 27, 2020

• Training and Fit Testing of Health Care Personnel for Reusable Elastomeric Half-Mask Respirators Compared With Disposable N95 Respirators
  Mar 25. Pompeii LA. JAMA.
  Opinion from SAB Member: Dr. J. Lance Lichtor
  In this research letter, the authors showed that health care workers can be rapidly fit tested and trained to use the reusable Elastomeric Half-Mask Respirators. These have the advantage over N95 respirators in that they are reusable. They cost about $30-$40 and they are used currently in about four major U.S. health systems.

May 13, 2020

• The impact of respiratory protective equipment on difficult airway management: a randomised, crossover, simulation study. Apr 26. Schumacher. Anaesthesia.
  This study from the U.K. examines intubation times and comfort in simulated difficult airway intubations using PAPR, “standard respirators” and normal surgical masks. Various intubating equipment was used. No significant differences were found for intubation times between the respirators, and PAPR had better vision, were cooler, and noisier. Though reassuring, the availability of different sorts of respirators is highly institution and individual specific, and the results of this investigation may be difficult to apply to all settings.

May 7, 2020

• Can N95 Respirators Be Reused after Disinfection? How Many Times?
  May 5. Liao. ACS Nano.
  Opinion from SAB Member: Dr. Lydia Cassorla
  Due to shortages of PPE, individuals and groups are seeking effective methods to decontaminate N95 masks designed for single use. While this report in the basic science literature from the Stanford-4C Air group does not include confirmatory testing of SARS-CoV-2 decontamination, it adds to current information about the effects of decontamination methods on the fabric of N95 masks. Based on their work, heat in a range of 70-85 degrees C in a static air oven for 30 min with varying degrees of relative humidity does not degrade the structure and function of the filter layer of masks up to 50 cycles. These are temperatures that have been shown in referenced work to be effective in inactivating SARS-CoV-2. The authors suggest that this is a potentially safe and relatively simple technique to decontaminate N95 masks for re-use by the same individual during the current pandemic. UVGI was a secondary option, with adequate retention of function for up to 10 cycles. Their work mostly involved fabric samples, using only a few whole masks due to shortages, and highlights the importance of ongoing fit evaluation, especially after 5 rounds of donning and doffing.

May 2, 2020

• Institution of a Novel Process for N95 Respirator Disinfection with Vaporized Hydrogen Peroxide in the setting of the COVID-19 Pandemic at a Large Academic Medical Center. May 1. Grossman. J Am Coll Surg.
  A multi-disciplinary team from Washington University School of Medicine, Barnes Jewish Hospital, and BJC Healthcare created a vaporized hydrogen peroxide (VHP) disinfection facility within their institution and developed a logistical framework to provide just-in-time large volume disinfection of N95 masks, returning each mask to its original wearer. In-house experience with the technique was leveraged, using Bioquell VHP and aeration equipment. They built a designated facility with separate areas for receiving used masks, disinfection, and off-gassing. Their first facility processes up to 1500 masks per cycle. Subsequent facilities were created in affiliated medical centers, scaled to local needs. Organizational and operational details are well described, including control processes to verify both sterilization and off gassing. Each user bags and labels his or her own mask, and masks from each work unit remain grouped throughout the process to facilitate timely return of batches to each work site for individuals to retrieve.

April 28, 2020

• Addressing the corona virus outbreak: will a novel filtered eye mask help? Apr 26. Douglas. Int J Infect Dis.
  Hermetically sealed eye masks tend to fog up in a few minutes. By modifying such a mask to allow filtered air entry laterally or above the eyes using N-95 or N-100 filter material, the authors create a Filtered Eye Mask (patent pending) which did not fog during a one hour experiment. Only prototypes were tested on one of the authors. No definitive investigation into virus penetration was performed.

April 25, 2020

• Barrier Shields: Not Just for Intubations in Today’s COVID-19 World? Apr 24. Tsai. Anesthesia & Analgesia.
  Instead of using shields just to prevent aerosol exposure during intubation, the author suggests leaving the shield in place throughout the case to provide protection during other aerosol generating procedures, such as suctioning, extubation, high flow oxygen delivery, or upper endoscopy. For rigid plastic barrier with arm ports, a clear drape can be used to cover the ports.

April 21, 2020

• Category: Infection Control: An Interim Solution to the Decreased Availability of Respirators against COVID-19
  Apr 15. Saggese. Anesthesia & Analgesia.
  Opinion from SAB Member: Dr. Barry Perlman
  In NYC, N95 respirator shortages have led healthcare workers to use substandard or unapproved options. Letter from NYC oral/maxillofacial surgeons in response to “Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic” http://dx.doi.org/10.1213/ANE.0000000000004841 describes a do-it-yourself reusable respirator made from an anesthesia mask, inline ventilator or HEPA filter, and elastic straps. This has minimal leakage around the edge and N100 filtration efficiency. It can be washed with soap and water or disinfectant. For non-aerosol generating procedures, they suggest eye protection and a Level 3 surgical mask with a “surgical mask brace” using rubber bands or tourniquets to create a better seal.

April 13, 2020

• Stockpiling Ventilators for Influenza Pandemics. June 1, 2017. Huang. CDC Emerging Infectious Diseases.
  Fabulous article on ventilator allocation in an epidemic. Written in 2017, could have been useful if put into practice 2 months ago. A piece to evaluate after this epidemic is calmed.
• The coronavirus pandemic and aerosols: Does COVID-19 transmit via expiratory particles? Apr 3. Asadi. Aerosol Science and Technology.
  Addresses a number of relevant issues based on the unfortunate truth that we really do not know how people are getting infected;
  • the plausibility that asymptomatic and presymptomatic individuals (do not cough or sneeze), not self-quarantining or being detected, might likely contribute to ongoing transmissibility
  • data from SARS-CoV-2 indicating that it remained aerosolized for about 1 hour
  • many variables involved re air speed/wind, temperature and other ambient environmental conditions.

April 8, 2020

• Converting Gas-Driven Ventilators from Oxygen to Air Apr 2. Ford. Anaesthesia.
  COVID-19 SAB Opinion from: Dr. Lydia Cassorla
  Bellows ventilators (read GE Healthcare) usually use piped 100% O2 to drive the bellows, consuming a volume equal to minute ventilation. Read this brief report to learn how to convert to compressed air for continuous use as an ICU ventilator. Note: An air tank would need to be on the machine for emergency backup.
• Covid-19: PHE upgrades PPE advice for all patient contacts with risk of infection. Apr 5. Sayburn. BMJ.
  Brief note regarding Public Health England revised PPE guidelines.
• Covid-19: the crisis of personal protective equipment in the US. Apr 5. Kamerow. BMJ.
  There simply is not enough personal protective equipment in the US. Both the federal government and the states have stockpiles, but demand exceeds supply.
• Personal protective equipment during the COVID-19 pandemic – a narrative review. Apr 5. Cook. Anaesthesia.
  Nicely detailed review of PPE and appropriate use, viral clearance based on room ventilation, and frank assessment of available evidence.

April 5, 2020

• A Framework for Rationing Ventilators and Critical Care Beds During the COVID-19 Pandemic. Mar 27. White. JAMA.
  COVID-19 SAB Opinion from: Dr. Philip Lumb
  This is an excellent discussion regarding scarce resource management in constrained circumstances. Unrestricted ventilator management has equated with successful weaning and/or terminal event; when constrained, choice of assignment requires triage. The discussion focuses on essential requirement for multidisciplinary preplanning and triage committee creation. The attached supplement from University of Pittsburgh serves as an informative and well-reasoned approach and protocol. There is a good discussion regarding setting patient and family expectations and the possibility of ventilator “reassignment” in triage situations.

April 2, 2020

• Sourcing Personal Protective Equipment During the COVID-19 Pandemic. Mar 28. Livingston. JAMA.
  Discusses CDC personal protective equipment requirements in normal times vs. during a pandemic.
• Utility of Substandard Face Mask Options for Health Care Workers During the COVID-19 Pandemic. Mar 30. Abd-Elsayed. Anesthesia & Analgesia.
  Reviews how effective different face mask options are for health care workers.
• Waste Not, Want Not: The Re-Usability of N95 Masks. Mar 30. Nathan. Anesthesia & Analgesia.
  Infographic outlining various perspectives on managing the reuse of N95 masks.

April 1, 2020

• Consensus Statement on Multiple Patients Per Ventilator. Mar 26. SCCM.
  SCCM, AARC, ASA, APSF, AACN, and CHEST a consensus statement on the concept of placing multiple patients on a single mechanical ventilator.
• Covid-19: Mercedes F1 to provide breathing aid as alternative to ventilator. Mar 30. Mahase. BMJ.
  Mercedes F1 will produce continuous positive airway pressure (CPAP) machines for the NHS to use on covid-19 patients with serious lung infections, as a less invasive alternative to ventilators.

March 30, 2020

• Recommended Strategies from the U.S. Public Health Service to Optimize Provision of Mechanical Ventilation. APSF.

March 28, 2020

• MIT Emergency Ventilator (E-Vent) Project.
• MIT Will Post Free Plans Online for an Emergency Ventilator That Can Be Built for $100. SciTechDaily.

March 27, 2020

• CDC: Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings. Last updated: March 27, 2020.
• CPAP Machines Were Seen As Ventilator Alternatives, But Could Spread COVID-19. NPR.
  Article emphasizes risk of non-invasive ventilation because of risk or aerosolizing virus and whether there are stopgap options.

March 26, 2020

• CDC: Strategies for Optimizing the Supply of PPE for COVID-19. Last updated: March 26, 2020.
• COVID-19 Town Hall Webinar on N95 masks and prioritizing our protection, understand the process to repurpose anesthesia gas machines to ventilators, collaborating with critical care teams and other practical patient care advice.

March 24, 2020

• Updated ASA, APSF, AAAA and AANA Joint Statement on PPE Amid COVID-19 Pandemic. March 24, 2020.