COVID-19 pandemic and mechanical ventilation: facing the present, designing the future

The Effects of Automatic Inspiratory Rise Time and Flow Termination on Operation of Closed-Loop Ventilation

BACKGROUND

Adaptive ventilation mode (AVM) is a automated mode of mechanical ventilation. AVM is comprable to adaptive support ventilation (ASV). Both recommend a tidal volume (VT) and breathing frequency (f) combination based on lung mechanics, but AVM also automatically adjusts rise time and flow termination of pressure support breaths. How these added features of AVM affect VT and f recommendations compared to ASV is not clear. The present study compared these 2 modes in a test lung with obstructive and restrictive mechanics.

METHODS

The experiment was performed in a simulated lung model in which the compliance (C) and resistance (R) could be altered independently. The ventilatory parameters at different minute volumes (MinVol%) in AVM or ASV mode were recorded.

RESULTS

When MinVol% was set at 100%, AVM provided a similar VT and f combination compared to ASV with decreasing compliance or increasing resistance. However, when MinVol% was increased to 250% simulating hyperventilation, for the severely obstructive lung (C60, R70) model, AVM provided a significantly higher f (26 ± 0.6 breaths/min vs 7.00 ± 0 breaths/min in ASV) and lower VT (240 ± 80 mL vs 491 ± 131 mL in ASV).

CONCLUSIONS

The addition of automatic control of rise time and flow termination functions did not affect recommended ventilator settings in AVM in the noncompliant or obstructive lung when minute ventilation (V̇E) was low. At higher V̇E, AVM compared to ASV recommended a ventilatory strategy with lower VT and higher f. These results need to be validated in patients.

Public voices on tie-breaking criteria and underlying values in COVID-19 triage protocols to access critical care: a scoping review

Background

To reduce the arbitrariness in the allocation of rare resources in intensive care units (ICU) in the context of the pandemic, tiebreakers were considered in some COVID-19 triage algorithms. They were also contemplated to facilitate the tragic decisions of healthcare workers when faced with two patients with similar prognosis and only one ICU bed available. Little is known about the public's perspective on tiebreakers.

Objectives

To consolidate the available scientific literature on public consultations, particularly on tiebreakers and their underlying values. Also, to obtain an overview of the key arguments presented by the participating public and to identify potential gaps related to this topic.

Methods

The steps described by Arksey and O'Malley was the preferred method to our approach. Seven electronic databases were searched from January 2020 to April 2022, using keywords for each database: PubMed, Medline, EMBASE, Web of Science, PsycINFO, EBM reviews, CINAHL complete. We also searched in Google and Google Scholar, and in the references of the articles found. Our analysis was mainly qualitative. A thematic analysis was performed to consider the public's perspectives on tiebreakers and their underlying values, according to these studies.

Results

Of 477 publications found, 20 were selected. They carried out public consultations through various methods: surveys (80%), interviews (20%), deliberative processes (15%) and others (5%) in various countries: Australia, Brazil, Canada, China, France, Germany, India, Iran, Italy, Japan, Korea, Netherlands, Portugal, Spain, Switzerland, Thailand, United Kingdom, and United States. Five themes emerged from our analysis. The public favored the life cycle (50%) and absolute age (45%) as a tiebreaker. Other values considered important were reciprocity, solidarity, equality, instrumental value, patient merit, efficiency, and stewardship. Among the new findings were a preference for patient nationality and those affected by COVID-19.

Conclusions

There is a preference for favoring younger patients over older patients when there is a tie between similar patients, with a slight tendency to favor intergenerational equity. Variability was found in the public's perspectives on tiebreakers and their values. This variability was related to socio-cultural and religious factors. More studies are needed to understand the public's perspective on tiebreakers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s44250-023-00027-9.

Use of recommended personal protective equipment among Brazilian health professionals during the COVID-19 pandemic

BACKGROUND: The COVID-19 pandemic is one of the biggest health crises in the world and the use of personal protective equipment (PPE) is significant measures to prevent the transmission of SARS-CoV-2. However, PPE needs to be used properly by healthcare professionals. OBJECTIVE: To analyze the use of PPE among Brazilian health professionals and associated factors during a period of the COVID-19 pandemic. METHODS: An analytical cross-sectional study was carried out from October to December 2020. For data collection, the respondent-driven sampling technique was used, adapted for social media, with a link to an online survey form. RESULTS: The study considered 12,086 Brazilian health professionals. Most (69%) used PPE recommended for the care of patients with suspected or diagnosed COVID-19. Factors associated with the use of PPE were: working in an Intensive Care Unit (ICU) or in a field hospital, receiving training, being provided with sufficient, high-quality PPE by the workplace and being an odontologist compared to nursing professionals. For procedures that generate aerosols in the context of COVID-19, 54.1% of them used the recommended PPE, the associated factors were: being married or in a stable relationship compared to a single/divorced professional, working in an ICU, being offered training, providing sufficient, high-quality PPE, and being an odontologist compared to nursing professionals. CONCLUSIONS: For the care of patients with COVID-19, 69% of health professionals used PPE properly, and several factors interfered with the use of this equipment.

VEMERS 2.0: Upgrading of an Emergency Use Ventilator from a Single Mandatory Volume Control Mode of Ventilation (VEMERS 1.0) to 8 Modes of Ventilation

The upgrading of an emergency use ventilator from a single mandatory volume control mode of ventilation (VEMERS 1.0) to 8 modes of ventilation (VEMERS 2.0) is described. The original VEMERS 1.0 was developed in the midst of the COVID-19 crisis in Chile (April to August 2020) following special but nonetheless strict guidelines specified by local medical associations and national health and scientific ministries. The upgrade to 8 modes of ventilation in VEMERS 2.0 was made possible with minor but transcendental changes to the original architecture. The main contribution of this research is that starting from a functional block diagram of an ICU mechanical ventilator and carrying a systematic analysis, the main function blocks are implemented in such a way that combinations of standard off-the-shelf pneumatic and electronic components can be used. This approach has both economical and technical advantages. No special parts need to be fabricated at all, and because of a wider variety of options, the use of extensively field-proven off-the-shelf commercial components assures better availability and lower costs when compared to that of conventional ICU mechanical ventilators, without sacrificing reliability. Given the promising results obtained with VEMERS 2.0 in the subsequent national certification process, the production of 40 VEMERS 2.0 units was sponsored by the Ministry of Science and the Ministry of Economy. Twenty units have been distributed among hospitals along the country. The purpose of VEMERS 2.0, as a low-cost but very reliable option, is to increase the number of mechanical ventilators available (3,000 for a population of 18,000,000) in the country to eventually reach a ratio similar to that of more developed countries. VEMERS is an open-source project for others to use the knowledge gained.

Air–Oxygen Blenders for Mechanical Ventilators: A Literature Review

Respiratory diseases are one of the most common causes of death in the world and this recent COVID-19 pandemic is a key example. Problems such as infections, in general, affect many people and depending on the form of transmission they can spread throughout the world and weaken thousands of people. Two examples are severe acute respiratory syndrome and the recent coronavirus disease. These diseases have mild and severe forms, in which patients gravely affected need ventilatory support. The equipment that serves as a basis for operation of the mechanical ventilator is the air–oxygen blender, responsible for carrying out the air–oxygen mixture in the proper proportions ensuring constant supply. New blender models are described in the literature together with applications of control techniques, such as Proportional, Integrative and Derivative (PID); Fuzzy; and Adaptive. The results obtained from the literature show a significant improvement in patient care when using automatic controls instead of manual adjustment, increasing the safety and accuracy of the treatment. This study presents a deep review of the state of the art in air–oxygen benders, identifies the most relevant characteristics, performs a comparison study considering the most relevant available solutions, and identifies open research directions in the topic.

Collaborative and Structured Network for Maintenance of Mechanical Ventilators during the SARS-CoV-2 Pandemic

The SARS-CoV-2 pandemic in Brazil has grown rapidly since the first case was reported on 26 February 2020. As the pandemic has spread, the low availability of medical equipment has increased, especially mechanical ventilators. The Brazilian Unified Health System (SUS) claimed to have only 40,508 mechanical ventilators, which would be insufficient to support the Brazilian population at the pandemic peak. This lack of ventilators, especially in public hospitals, required quick, assertive, and effective actions to minimize the health crisis. This work provides an overview of the rapid deployment of a network for maintaining disused mechanical ventilators in public and private healthcare units in some regions of Brazil during the SARS-CoV-2 pandemic. Data referring to the processes of maintaining equipment, acquiring parts, and conducting national and international training were collected and analyzed. In total, 4047 ventilators were received by the maintenance sites, and 2516 ventilators were successfully repaired and returned to the healthcare units, which represents a success rate of 62.17%. The results show that the maintenance initiative directly impacted the availability and reliability of the equipment, allowing access to ventilators in the public and private health system and increasing the capacity of beds during the pandemic.

COVID-19: instruments for the allocation of mechanical ventilators-a narrative review

After the World Health Organization declared COVID-19 to be a pandemic, the elaboration of comprehensive and preventive public policies became important in order to stop the spread of the disease. However, insufficient or ineffective measures may have placed health professionals and services in the position of having to allocate mechanical ventilators. This study aimed to identify instruments, analyze their structures, and present the main criteria used in the screening protocols, in order to help the development of guidelines and policies for the allocation of mechanical ventilators in the COVID-19 pandemic. The instruments have a low level of scientific evidence, and, in general, are structured by various clinical, non-clinical, and tiebreaker criteria that contain ethical aspects. Few instruments included public participation in their construction or validation. We believe that the elaboration of these guidelines cannot be restricted to specialists as this question involves ethical considerations which make the participation of the population necessary. Finally, we propose seventeen elements that can support the construction of screening protocols in the COVID-19 pandemic.