Conceptual model of low-cost improvised bubble continuous positive airway pressure device for adults and its potential use in the COVID-19 pandemic.

Low-cost improvised continuous positive airway pressure (CPAP) device is safe and efficacious in neonatal respiratory distress. There is a great necessity for similar device in adults, and this has been especially made apparent by the recent Coronavirus Disease 2019 (COVID-19) pandemic, which is unmasking the deficiencies of healthcare system in several low-resource countries. We propose a simplified and inexpensive model of improvised CPAP in adults using locally available resources including aquarium air pumps and a novel pressure release mechanism. Although the safety and efficacy of improvised CPAP in adults are not established, the conceptual model we propose has the potential to serve as a lifesaving technology in many low-resource settings during this ongoing pandemic and thus calls for expedited research.

Recommended Approaches to Minimize Aerosol Dispersion of SARS-CoV-2 During Noninvasive Ventilatory Support Can Cause Ventilator Performance Deterioration: A Benchmark Comparative Study.

BACKGROUND: SARS-CoV-2 aerosolization during noninvasive positive-pressure ventilation may endanger health care professionals. Various circuit setups have been described to reduce virus aerosolization. However, these setups may alter ventilator performance. RESEARCH QUESTION: What are the consequences of the various suggested circuit setups on ventilator efficacy during CPAP and noninvasive ventilation (NIV)? STUDY DESIGN AND METHODS: Eight circuit setups were evaluated on a bench test model that consisted of a three-dimensional printed head and an artificial lung. Setups included a dual-limb circuit with an oronasal mask, a dual-limb circuit with a helmet interface, a single-limb circuit with a passive exhalation valve, three single-limb circuits with custom-made additional leaks, and two single-limb circuits with active exhalation valves. All setups were evaluated during NIV and CPAP. The following variables were recorded: the inspiratory flow preceding triggering of the ventilator, the inspiratory effort required to trigger the ventilator, the triggering delay, the maximal inspiratory pressure delivered by the ventilator, the tidal volume generated to the artificial lung, the total work of breathing, and the pressure-time product needed to trigger the ventilator. RESULTS: With NIV, the type of circuit setup had a significant impact on inspiratory flow preceding triggering of the ventilator (P < .0001), the inspiratory effort required to trigger the ventilator (P < .0001), the triggering delay (P < .0001), the maximal inspiratory pressure (P < .0001), the tidal volume (P = .0008), the work of breathing (P < .0001), and the pressure-time product needed to trigger the ventilator (P < .0001). Similar differences and consequences were seen with CPAP as well as with the addition of bacterial filters. Best performance was achieved with a dual-limb circuit with an oronasal mask. Worst performance was achieved with a dual-limb circuit with a helmet interface. INTERPRETATION: Ventilator performance is significantly impacted by the circuit setup. A dual-limb circuit with oronasal mask should be used preferentially.

Performance of EasyBreath Decathlon Snorkeling mask for delivering continuous positive airway pressure.

During the COVID-19 pandemic, the need for noninvasive respiratory support devices has dramatically increased, sometimes exceeding hospital capacity. The full-face Decathlon snorkeling mask, EasyBreath (EB mask), has been adapted to deliver continuous positive airway pressure (CPAP) as an emergency respiratory interface. We aimed to assess the performance of this modified EB mask and to test its use during different gas mixture supplies. CPAP set at 5, 10, and 15 cmH2O was delivered to 10 healthy volunteers with a high-flow system generator set at 40, 80, and 120 L min-1 and with a turbine-driven ventilator during both spontaneous and loaded (resistor) breathing. Inspiratory CO2 partial pressure (PiCO2), pressure inside the mask, breathing pattern and electrical activity of the diaphragm (EAdi) were measured at all combinations of CPAP/flows delivered, with and without the resistor. Using the high-flow generator set at 40 L min-1, the PiCO2 significantly increased and the system was unable to maintain the target CPAP of 10 and 15 cmH2O and a stable pressure within the respiratory cycle; conversely, the turbine-driven ventilator did. EAdi significantly increased with flow rates of 40 and 80 L min-1 but not at 120 L min-1 and with the turbine-driven ventilator. EB mask can be safely used to deliver CPAP only under strict constraints, using either a high-flow generator at a flow rate greater than 80 L min-1, or a high-performance turbine-driven ventilator.

Use of Helmet CPAP in COVID-19 - A practical review.

Helmet CPAP (H-CPAP) has been recommended in many guidelines as a noninvasive respiratory support during COVID-19 pandemic in many countries around the world. It has the least amount of particle dispersion and air contamination among all noninvasive devices and may mitigate the ICU bed shortage during a COVID surge as well as a decreased need for intubation/mechanical ventilation. It can be attached to many oxygen delivery sources. The MaxVenturi setup is preferred as it allows for natural humidification, low noise burden, and easy transition to HFNC during breaks and it is the recommended transport set-up. The patients can safely be proned with the helmet. It can also be used to wean the patients from invasive mechanical ventilation. Our article reviews in depth the pathophysiology of COVID-19 ARDS, provides rationale of using H-CPAP, suggests a respiratory failure algorithm, guides through its setup and discusses the issues and concerns around using it.

Bubble CPAP splitting: innovative strategy in resource-limited settings.

BACKGROUND: Non-invasive respiratory support for neonates using bubble continuous positive airway pressure (bCPAP) delivery systems is now widespread owing to its safety, cost effectiveness and easy applicability. Many innovative solutions have been suggested to deal with the possible shortage in desperate situations like disasters, pandemics and resource-limited settings. Although splitting of invasive ventilation has been reported previously, no attempts to split non-invasive respiratory support have been reported. OBJECTIVE: The primary objective was to test the feasibility of splitting the bCPAP assembly using a T-piece splitter in a simulation model. METHODS: A pilot simulation-based study was done to split a single bCPAP assembly using a T-piece. Other materials consisted of a heated humidification system, an air oxygen blender, corrugated inspiratory and expiratory tubing, nasal interfaces and two intercostal chest tube drainage bags. Two pressure manometers were used simultaneously to measure delivered pressures at different levels of set bCPAPs at the expiratory limb of nasal interfaces. RESULTS: Pressures measured at the expiratory end of two nasal interfaces were 5.1 and 5.2 cm H2O, respectively, at a flow of 6 L/min and a water level of 5 cm H2O in both chest bags. When tested across different levels of set continuous positive airway pressure (3-8 cmH2O) and fractional inspired oxygen concentration (0.30-1.0), measured parameters corresponded to set parameters. CONCLUSION: bCPAP splitting using a T-piece splitter is a technically simple, feasible and reliable strategy tested in a simulation model. Further testing is needed in a simulated lung model.

Preclinical validation of occupational and environmental safety of an isolation system for noninvasive ventilation in COVID-19 and other aerosol-transmitted infections.

Background: The current SARS-CoV-2 pandemic has provoked the collapse of some health systems due to insufficient intensive care unit capacity. The use of continuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) therapies has been limited in consideration of the risk of occupational infection in health-care professionals. Aims: In preclinical experimental simulations, evaluate occupational and environmental safety of the newly developed isolation system for aerosol-transmitted infections (ISATI). Method: Simulations were conducted to test ISATI's capability to isolate aerosolized molecular (caffeine), and biological (SARS-CoV-2 synthetic RNA) markers. Caffeine deposition was analyzed on nitrocellulose sensor discs by proton nuclear magnetic resonance spectroscopy. Synthetic SARS-CoV-2 detection was performed by reverse transcription-polymerase chain reaction. Results: ISATI demonstrated efficacy in isolating molecular and biological markers within the enclosed environment in simulated conditions of CPAP, HFNO and mechanical ventilation therapy. Neither the molecular marker nor substantial amounts of synthetic SARS-CoV-2 RNA were detected in the surrounding environment, outside ISATI, indicating appropriate occupational safety for health-care professionals. Conclusion: Aerosolized markers were successfully contained within ISATI in all experimental simulations, offering occupational and environmental protection against the dissemination of aerosolized microparticles under CPAP or HFNO therapy conditions, which are indicated for patients with acute respiratory infections.

Noninvasive mechanical ventilation in the COVID-19 era: Proposal for a continuous positive airway pressure closed-loop circuit minimizing air contamination, oxygen consumption, and noise.

Noninvasive continuous positive airway pressure (NIV-CPAP) is effective in patients with hypoxemic respiratory failure. Building evidence during the COVID-19 emergency reported that around 50% of patients in Italy treated with NIV-CPAP avoided the need for invasive mechanical ventilation. Standard NIV-CPAP systems operate at high gas flow rates responsible for noise generation and inadequate humidification. Furthermore, open-configuration systems require a high concentration of oxygen to deliver the desired FiO2 . Concerns outlined the risk for aerosolization in the ambient air and the possible pressure drop in hospital supply pipes. A new NIV-CPAP system is proposed that includes automatic control of patient respiratory parameters. The system operates as a closed-loop breathing circuit that can be assembled, combining a sleep apnea machine with existing commercially available components. Analytical simulation of a breathing patient and simulation with a healthy volunteer at different FiO2 were performed. Inspired and expired oxygen fraction and inspired and expired carbon dioxide pressure were recorded at different CPAP levels with different oxygen delivery. Among the main findings, we report (a) a significant (up to 30-fold) reduction in oxygen feeding compared to standard open high flow NIV-CPAP systems, to assure the same FiO2 levels, and (b) a negligible production of the noise generated in ventilatory systems, and consequent minimization of patients' discomfort. The proposed NIV-CPAP circuit, reshaped in closed-loop configuration with the blower outside of the circuit, has the advantages of minimizing aerosol generation, environmental contamination, oxygen consumption, and noise to the patient. The system is easily adaptable and can be implemented using standard CPAP components.

Electrostatic Filters to Reduce COVID-19 Spread in Bubble CPAP: An in vitro Study of Safety and Efficacy.

BACKGROUND: Bubble CPAP may be used in infants with suspected or confirmed COVID-19. Electrostatic filters may reduce cross infection. This study aims to determine if including a filter in the bubble CPAP circuit impacts stability of pressure delivery. METHODS: A new electrostatic filter was placed before (pre) or after (post) the bubble CPAP generator, or with no filter (control) in an in vitro study. Pressure was recorded at the nasal interface for 18 h (6 L/min; 7 cm H2O) on 3 occasions for each configuration. Filter failure was defined as pressure >9 cm H2O for 60 continuous minutes. The filter was weighed before and after each experiment. RESULTS: Mean (SD) time to reach the fail point was 257 (116) min and 525 (566) min for filter placement pre- and post-CPAP generator, respectively. Mean pressure was higher throughout in the pre-generator position compared to control. The filter weight was heavier at end study in the pre- compared to the post-generator position. CONCLUSIONS: Placement of the filter at the pre-generator position in a bubble CPAP circuit should be avoided due to unstable mean pressure. Filters are likely to become saturated with water over time. The post-generator position may accommodate a filter, but regular pressure monitoring and early replacement are required.

[Alternative CPAP methods for the treatment of secondary serious respiratory failure due to pneumonia by COVID-19]. / Métodos alternativos de CPAP para el tratamiento de insuficiencia respiratoria grave secundaria a neumonía por COVID-19.

INTRODUCTION: The use of devices that provide continuous positive pressure in the airway has shown improvement in various pathologies that cause respiratory failure. In the COVID-19 pandemic episode the use of these devices has become widespread, but, due to the shortage of conventional continuous positive airway pressure (CPAP) devices, alternative devices have been manufactured. The objective of this study is to describe the use of these devices, as well as their efficacy. MATERIAL AND METHODS: Data are collected from patients admitted for pneumonia due to COVID-19 at the IFEMA Field Hospital. Data are collected from 23 patients with respiratory failure and need for ventilatory support. RESULTS: Study carried out on a total of 23 patients, dated admission to IFEMA. Alternative CPAP was used in five patients (21.7%), while ventilatory support with a reservoir mask or Ventimask Venturi effect was used in the remaining 18 patients (78.3%). A progressive increase in saturation is observed in those patients in whom alternative CPAP was used (from 94% on average to 98 and 99% on average after 30 and 60 minutes with the mask, respectively), although this change was not significant (p = 0.058 and p = 0.122, respectively). No significant change in RF was observed at the beginning and end of the measurement in patients who used alternative CPAP (p = 0.423), but among those who did not use alternative CPAP (p = 0.001). A statistically significant improvement in the variable oxygen saturation / fraction inspired by oxygen is observed in patients who used alternative CPAP (p = 0.040) CONCLUSION: The use of these devices has helped the ventilatory work of several patients by improving their oxygenation parameters. To better observe the evolution of patients undergoing this therapy and compare them with patients with other types of ventilatory support, further studies are necessary.

Continuous Positive Airway Pressure (CPAP) face-mask ventilation is an easy and cheap option to manage a massive influx of patients presenting acute respiratory failure during the SARS-CoV-2 outbreak: A retrospective cohort study.

INTRODUCTION: Because of the COVID-19 pandemic, intensive care units (ICU) can be overwhelmed by the number of hypoxemic patients. MATERIAL AND METHODS: This single centre retrospective observational cohort study took place in a French hospital where the number of patients exceeded the ICU capacity despite an increase from 18 to 32 beds. Because of this, 59 (37%) of the 159 patients requiring ICU care were referred to other hospitals. From 27th March to 23rd April, consecutive patients who had respiratory failure or were unable to maintain an SpO2 > 90%, despite receiving 10-15 l/min of oxygen with a non-rebreather mask, were treated by continuous positive airway pressure (CPAP) unless the ICU physician judged that immediate intubation was indicated. We describe the characteristics, clinical course, and outcomes of these patients. The main outcome under study was CPAP discontinuation. RESULTS: CPAP was initiated in 49 patients and performed out of ICU in 41 (84%). Median age was 65 years (IQR = 54-71) and 36 (73%) were men. Median respiratory rate before CPAP was 36 (30-40) and median SpO2 was 92% (90-95) under 10 to 15 L/min oxygen flow. Median duration of CPAP was 3 days (IQR = 1-5). Reasons for discontinuation of CPAP were: intubation in 25 (51%), improvement in 16 (33%), poor tolerance in 6 (12%) and death in 2 (4%) patients. A decision not to intubate had been taken for 8 patients, including the 2 who died while on CPAP. Two patients underwent less than one hour CPAP for poor tolerance. In the end, 15 (38%) out of 39 evaluable patients recovered with only CPAP whereas 24 (62%) were intubated. CONCLUSIONS: CPAP is feasible in a non-ICU environment in the context of massive influx of patients. In our cohort up to 1/3 of the patients presenting with acute respiratory failure recovered without intubation.

Sleep Breathing Disorders in the COVID-19 Era: Italian Thoracic Society Organizational Models for a Correct Approach to Diagnosis and Treatment.

The attenuation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, at least in Italy, allows a gradual resumption of diagnostic and therapeutic activities for sleep respiratory disorders. The knowledge on this new disorder is growing fast, but our experience is still limited and when a physician cannot rely on evidence-based medicine, the experience of his peers can support the decision-making and operational process of reopening sleep laboratories. The aim of this paper is to focus on the safety of patients and operators accessing hospitals and the practice of diagnosing and treating sleep-related respiratory disorders. The whole process requires a careful plan, starting with a triage preceding the access to the facility, to minimize the risk of infection. Preparation of the medical record can be performed through standard questionnaires administered over the phone or by e-mail, including an assessment of the COVID-19 risk. The home sleep test should include single-patient sensors or easy-to-sanitize material. The use of nasal cannulas is discouraged in view of the risk of the virus colonizing the internal reading chamber, since no filter has been tested and certified to be used extensively for coronavirus due to its small size. The adaptation to positive airway pressure (PAP) treatment can also be performed mainly using telemedicine procedures. In the adaptation session, the mask should be new or correctly sanitized and the PAP device, without a humidifier, should be protected by an antibacterial/antiviral filter, then sanitized and reassigned after at least 4 days since SARS-CoV-2 was detected on some surfaces up to 72 h after. Identification of pressure should preferably be performed by telemedicine. The patient should be informed of the risk of spreading the disease in the family environment through droplets and how to reduce this risk. The follow-up phase can again be performed mainly by telemedicine both for problem solving and the collection of data. Public access to hospital should be minimized and granted to patients only. Constant monitoring of institutional communications will help in implementing the necessary recommendations.

COVID-19: minimising contaminated aerosol spreading during CPAP treatment.

BACKGROUND: The COVID-19 pandemic has raised concern for healthcare workers getting infected via aerosol from non-invasive respiratory support of infants. Attaching filters that remove viral particles in air from the expiratory limb of continuous positive airway pressure (CPAP) devices should theoretically decrease the risk. However, adding filters to the expiratory limb could add to expiratory resistance and thereby increase the imposed work of breathing (WOB). OBJECTIVE: To evaluate the effects on imposed WOB when attaching filters to the expiratory limb of CPAP devices. METHODS: Two filters were tested on three CPAP systems at two levels of CPAP in a mechanical lung model. Main outcome was imposed WOB. RESULTS: There was a minor increase in imposed WOB when attaching the filters. The differences between the two filters were small. CONCLUSION: To minimise contaminated aerosol generation during CPAP treatment, filters can be attached to expiratory tubing with only a minimal increase in imposed WOB in a non-humidified environment. Care has to be taken to avoid filter obstruction and replace filters as recommended.

Quick Thinking Turns out Low-Cost Ventilators.

As the number of coronavirus 2019 disease (COVID-19) cases in the United States began mounting in the early weeks of March, health care workers raised the alarm about a looming shortage of ventilators to treat patients. On March 30, 2020, Ford Motor Company announced plans to produce 50,000 ventilators in 100 days [1], and General Motors followed suit on April 8, stating that it would deliver out 6,000 ventilators by the end of May and another 24,000 by August [2].

COVID-19 and respiratory support devices.

There are significant logistical challenges to providing respiratory support devices, beyond simple oxygen flow, when centres run out of supplies or do not have these devices at all, such as in low resource settings. At the peak of the COVID-19 crisis, it was extremely difficult to import medical equipment and supplies, because most countries prohibited the medical industry from selling outside of their own countries. As a consequence, engineering teams worldwide volunteered to develop emergency devices, and medical experts in mechanical ventilation helped to guide the design and evaluation of prototypes. Although regulations vary among countries, given the emergency situation, some Regulatory Agencies facilitated expedited procedures. However, laboratory and animal model testing are crucial to minimize the potential risk for patients when treated with a device that may worsen clinical outcome if poorly designed or misused.