In this section, we explore the second component of the 4 S framework: stuff. Healthcare systems including China, Italy, and the U.S. have struggled to maintain sufficient medical supplies during peak need of the pandemic. We describe a few examples that illuminate the importance of having the appropriate materials to respond to emerging health needs. In addition to those discussed below, testing is a critical need as well; it is discussed in detail in Module 1. The inclusion of point of care ultrasound testing will be critical particularly in lower resourced settings where widespread PCR-based testing may not be feasible.
As discussed in Module 6, personal protective equipment (PPE) is essential to the safety of healthcare professionals and prevention of virus spread in clinical environments. The Centers for Disease Control and Prevention (CDC), anticipating critical shortages, issued recommendations for prolonged use and re-use of masks and face shields, use after expiration dates, and alternatives like cloth masks or bandanas when no masks are available. However, they acknowledge that some of these practices are less efficacious than conventional PPE. In LMICs where such shortages are more common at baseline, this pandemic will make adequate protection for providers and patients difficult. Innovators have been considering how to address this need. Here we summarize examples of such potential innovations.
Due to an inadequate supply of PPE in the Philippines, student organizations and youth groups have created alternative means to procure them. This has led to DIY face shields designed and produced by graduating medical interns from the Ateneo School of Medicine & Public Health.
This initiative has been adopted by other institutions under the umbrella of Ateneo Professional Schools (APS), including law and business schools. Its rising popularity has prompted many independent groups to create their own versions of the face shields in order to aid in the procurement of much needed PPE in their respective localities. Through this widespread initiative, thousands of face shields have been donated to local medical systems. These DIY face shields can be made using recycled plastic bottles or sheets of acetate, recycled bubble wrap or strips of foam, garter, and common office supplies. A tutorial video can be accessed here.
The aerosol box, originally designed by Taiwan-based anesthesiologist Dr. Lai Hsien-yung, was developed to provide additional protection during aerosol-generating procedures (AGPs) like endotracheal intubation. This is of particular importance in COVID-19, as rapid clinical deterioration often necessitates rapid intubation. Performing AGPs places practitioners at higher risk of viral exposure and thus requires use of additional barriers for protection.
The protective tool is designed to be placed over the patient’s head with two holes to allow a physician’s hands to be inserted to perform procedures. The clear acrylic or poly-carbonate material makes for an inexpensive but effective barrier without interfering with visibility.
This device was reportedly first introduced in the Philippines by Dr. Frances Legaspi, a physician at Antipolo Doctors Hospital, and her brother, Anton Legaspi. Many independent groups in the country began mass-producing the aerosol box to meet PPE demands for critical care settings. The design continues to be improved, including modified dimensions to bring costs down from US$66 to US$29 per unit, larger holes to facilitate easier arm movement, and adjusting dimensions to add a slanted viewing pane.
The original blueprint by Dr. Hsien-yung is free for non-commercial purposes with proper attribution. Demonstration videos can be found here:
Mask decontamination and re-use has been considered in the U.S. for past outbreaks. Two important questions that must be addressed with this process include: 1) Does decontamination impair the integrity of masks 2) Is the efficacy for eliminating viruses high enough?
First, the maximum survival time of about 72 hours of SARS-CoV-2 means that masks could be re-used without sterilization. For unsoiled masks, the CDC suggests a daily rotation of 5 masks, either hanging masks between use or placing them in breathable paper bags between uses, such that any virus would decompose before re-use.
A number of other decontamination methods have been explored with varied success. Microwave oven irradiation melts some materials following prolonged exposure, while bleach damages filtration efficacy and leaves a toxic scent which detracts from the user experience, making neither a robust option for widespread decontamination. Ultraviolet germicidal irradiation (UVGI), ethylene oxide, and vaporized hydrogen peroxide (VHP) all preserve integrity of mask filtration. However, UVGI decreases the structural integrity of masks over time which will limit the number of disinfection cycles per mask.
The U.S. Environmental Protection Agency includes hydrogen peroxide in a list of disinfectants effective against SARS-CoV-2. A group at Duke University developed a method to disinfect masks using a vaporized hydrogen peroxide solution in a room with masks hanging on clothes-lines to be fully exposed.
High energy UV-C radiation has been shown to kill SARS-CoV and MERS, and it is expected to work in SARS-CoV-2 as well given their structural similarity. A group at University of Nebraska developed a decontamination method by hanging up masks between two large UV-C sources with good results (see image below). There are also some industrial approaches to mask sterilization, like those currently being used in Boston hospitals.
Given the shortages of conventional N-95 respirators and surgical masks, unconventional mask alternatives are being widely made. While the difference between N-95 and surgical masks is not significant for influenza, cloth masks have been shown to be inferior to conventional medical masks in a large randomized controlled trial. However, it is possible that with the correct materials or an added filter, washable cloth masks could fill an important need when suitable first-line materials are unavailable. For example, UF Anesthesiology is using Halyard H600 two-ply spun polypropylene to make masks with minimal particulate penetration. Researchers at Boston Children’s Hospital also produced a washable, inexpensive mask from available hospital materials, as seen below or at this link for a video description.
How could cloth masks be improved to be equivalent to medical-grade masks? What would you do to mass-produce them for medical professionals during a shortage?
Another example of the “stuff” that is required to care for COVID-19 patients is oxygen and the means to deliver it Oxygen delivery is a critical need given that the cardinal manifestation of COVID-19 prompting hospitalization is hypoxemic respiratory failure progressing to acute respiratory distress syndrome (ARDS). Healthcare facilities in resource-limited settings have many barriers to delivering oxygen to patients. According to a 2010 survey of health care facilities in 12 African countries, less than half reported uninterrupted oxygen access, and less than a quarter had an oxygen concentrator. Only 35% of these health care facilities have access to electricity. In another study in the Lancet from 2010, 19% of 77,700 surveyed surgical rooms, with a geographically and demographically diverse representation from over 50 countries, did not have access to pulse oximetry.
Successful oxygen treatment requires an oxygen source, either from oxygen cylinders, oxygen concentrators, or liquid oxygen; and the ability to deliver oxygen effectively, requiring pulse oximeters, tubing, and trained staff. Low resource settings typically depend on oxygen cylinders or oxygen concentrators. Cylinders require a supply chain, transportation, and flow meters, and may have leakage. Oxygen concentrators require electricity and technicians who can repair the devices. If electricity is reliable, oxygen concentrators are more cost-effective than oxygen cylinders. In settings with unreliable electricity, oxygen cylinders may be preferred. A possible decision tree for deciding between the use of oxygen cylinders and oxygen concentrators in resource-limited settings is based on a cost-effectiveness analysis done in Gambia is shown below.
Oxygen Decision Tree (Howie et al. WHO Bulletin 2009)
Most hospitals and healthcare facilities in HICs use liquid oxygen. Two major medical gas companies that provide liquid oxygen and oxygen cylinders in the U.S. and around the globe are facing increasing demand for their products. These global medical gas companies are currently able to manage this demand, and have started preparing their supply chain to address potential future bottlenecks.
Should governments of HICs start to prepare for oxygen shortages? How should they do so? Should they favor oxygen concentrators or cylinders?
Along the lines of oxygen, respiratory support is also a critical need for COVID-19. Here we summarize well-known estimates of ventilator shortages in HICs, explore implications for LMICs, and provide examples of innovations being explored to address this gap in supply versus demand.
Currently there are an estimated 60,000 to 160,000 ventilators in the U.S. However, it is estimated that the COVID-19 pandemic may require up to 1 million ventilators. In addition to the shortage of ventilator equipment and insufficient production of ventilator parts and consumables, the U.S. may face other challenges relating to “Staff” who can operate ventilators, including a lack of skilled respiratory therapists and biomedical engineers to support ventilator use and function. Furthermore, currently, procedures that could decrease the need for intubation and increase the safety of extubation, such as high flow nasal cannula (HFNC), CPAP, and BiPAP, are relatively contraindicated due to the hypothetical risk of aerosolization of SARS-CoV-2.
Resource-limited settings, such as rural areas in LMICs, have long struggled with the emerging scarcity that HICs are facing due to the surge of critically ill COVID-19 patients, including lack of ICU beds, lack of ventilatory equipment, lack of skilled technicians to operate ventilators, and an inability to repair ventilators. Healthcare facilities in LMICs may face additional challenges such as inability to monitor patients’ oxygen saturations or arterial blood gas (ABG) readings, lack of portable x-rays, inconsistent access to electricity, and the aforementioned challenges with oxygen delivery. Some studies have shown evidence of high mortality rates even among the relatively few patients who are able to access invasive mechanical ventilation. This is often due to a lack of or inadequate access to ancillary support services, such as portable x-rays, sedation, and suction devices.
Given this problem, experts explored a range of frameworks for practical guidance on administering respiratory support for those who are critically ill in resource-limited settings. One such framework proposed by Inglis, Ayebale, and Schultz is found in the figure below.
For those patients who require ventilatory support, the following points have been recommended in the past for advanced ventilatory support and management, especially in resource-limited settings:
Elevate the head of the bed to a semi-upright position (to prevent ventilator-associated pneumonia)
Use volume control modes instead of pressure control
Monitor end-tidal carbon dioxide (ETCO2) if possible
Perform spontaneous breathing trials daily to see if a patient can be weaned off of the ventilator and use low level of pressure support during spontaneous breathing trials
Before extubation, make sure to have staff, PPE, and resources to re-intubate if necessary
Despite established guidelines for managing complications of COVID-19 such as ARDS, best practices cannot be adopted globally due to resource constraints. In the following sections, we explore alternative options that frontline healthcare workers may consider when caring for COVID-19 patients in settings with limited access to ventilators. These include: noninvasive ventilatory support, placing non-ventilated patients in the prone position, sharing a single ventilator amongst multiple patients, and bag valve masking. All these options are discussed in the setting of a limited number of ventilators and skilled technicians to run and maintain ventilators.
One possible, but ill-advised, option for respiratory support in the case of treating potential ARDS in COVID-19 patients is the use of noninvasive ventilatory support (such as CPAP or BiPAP). There is strong evidence for the use of noninvasive ventilation (NIV) in the treatment of chronic obstructive pulmonary disease (COPD) and heart failure exacerbations; NIV has even been shown to be effective in reducing mortality in LMICs for these indications. However, ARDS has been shown to be a strong predictor of BiPAP/CPAP failure. One possible use for NIV in the setting of ARDS is a 1-hour trial in patients with mild/moderate disease, with close monitoring, and prompt intubation after this one hour period if the patient’s clinical status has deteriorated or not improved. Another potential use is to help wean patients who have passed spontaneous breathing trials and are no longer hypoxemic off of mechanical ventilation. The main risk of noninvasive ventilation use in the setting of ARDS is a delay in the time to a needed endotracheal intubation. Furthermore, in COVID-19 patients, BiPAP/CPAP/HFNC also carry a risk of aerosolization and further spread of the virus and should be avoided for this reason if possible. Therefore, while this is clearly an insufficient long-term option with an undesirable risk profile, NIV might play a temporary role when ventilators are not readily available.
There is good evidence that laying ventilated ARDS patients on their abdomens (proning) improves outcomes. There are physiological reasons for the benefits of proning, such as improving ventilation perfusion (VQ) matching by reducing the dorsal ventral transpulmonary pressure difference and improving perfusion. This has prompted some providers to attempt proning non-ventilated patients. In a retrospective analysis, prone positioning for nonintubated patients with hypoxemic respiratory failure has been shown to improve oxygenation. It thus may be helpful to consider placing ventilated and non-ventilated patients with ARDS due to COVID-19 in the prone position to improve oxygenation, especially in the setting of limited resources for ventilation. Proning patients does, however, carry risks, such as unintentional extubation, arrhythmias, falls, loss of a central venous line or peripheral venous line, and airway edema. To try to mitigate these risks, some checklists have been published to improve safety prior to and during prone maneuvers: Oliveira et al. Rev Bras Ter Intensiva. 2017.
Many critical care or anesthesia physician, nursing, and allied health professional organizations have released a joint statement to advise against sharing one ventilator amongst multiple patients due to the current technological limitations in being able to do so safely. This joint statement outlines many issues with ventilator sharing, including the need for external monitoring of patients, difficulty managing PEEP levels in multiple patients at once, difficulty with alarm management, ethical issues, and more. The societies which authored this joint statement believe that it would be dangerous to consider ventilating multiple patients on the same ventilator settings, as this would increase the risk for all patients involved when there is an already 40-60% mortality rate for an ARDS patient on a single ventilator in an ideal setting. However, in light of resource limitations seen during the COVID-19 pandemic, some have opted for this controversial and non-evidence-based practice; physicians have already initiated ventilator sharing between two patients with similar ventilatory requirements at New York Presbyterian Hospital. On March 31st, 2020, the Surgeon General issued technical guidance on co-ventilating two patients but endorsed this only as the absolute last resort, when the alternatives are either death or manual long-term bag valve mask ventilation for patients.
In some resource-limited settings or disaster resource settings, long-term “hand bagging” or manual bag valve masking may be the only option. Medical students, nurses, or even non-medical professionals such as family members or the National Guard may be required to bag valve mask patients for extended periods of time if there is a shortage of ventilators. There is an increasing likelihood of needing to bag valve mask patients for extended periods of time during the COVID-19 pandemic. However, bag-valve mask ventilation of a patient is considered an aerosolizing procedure and should ideally be done by providers who are wearing PPE that provides protection against aerosol transmission of COVID-19 (CDC).
If you were a country with a low current burden of COVID-19, how would you make the decision to regulate trade of importing/exporting ventilators?
Helpful resources: India’s response, brief description of responses of other European countries, China’s response
What are possible innovations that could make extended use of the bag valve mask a more feasible alternative to ventilators?
Helpful resources: Technology from Rice university and Metric technologies, MIT E-vent, Umbulizer (low cost ventilators)