Assessing the performance of the Whisperflow continuous positive airway pressure generator: a bench study

Helmet continuous positive airway pressure for patients' transport using a single oxygen cylinder: A bench study

BACKGROUND

Continuous positive airway pressure (CPAP) is frequently used to treat patients with acute respiratory failure in out-of-hospital settings. Compared to a facemask, the helmet has many advantages for the patient but requires a minimum gas flow of 60 L/min to avoid CO2 rebreathing. The aim of the present bench study was to evaluate the performance of four Venturi devices, connected to a single oxygen cylinder, in delivering helmet-CPAP with clinically relevant gas flow, fraction of inspired oxygen (FiO2), and positive end-expiratory pressure (PEEP) values.

METHODS

Three double-inlet Venturi systems (EasyVent, Ventuplus, Compact-HAR) were connected to full 5-L oxygen cylinders using a double flowmeter, and their oxygen requirements to reach different setups (flow 60-80 L/min; FiO2 0.4-0.5-0.6, PEEP 7.5-10-12.5 cmH2O) were tested. The fourth Venturi system (O2-MAX) was directly attached to the tank, and the flow and FiO2 delivered at preset FiO2 0.3 and 0.6 were recorded. The runtime of the cylinder was assessed.

RESULTS

EasyVent, Ventuplus, and O2-MAX were able to deliver helmet-CPAP with clinically useful setups when connected to a single oxygen cylinder, while Compact-HAR did not. The runtime of the cylinders ranged between 28 and 60 minutes according to the preset flow and FiO2. The delivered gas flow decreased slowly and linearly with the drop in cylinder pressure until its exhaustion.

CONCLUSIONS

Helmet-CPAP might be provided using portable Venturi systems connected to an oxygen cylinder, but not all of them are able to deliver it. The use of a double flowmeter allows delivery of both high flow and high FiO2 when double-inlet Venturi systems are used. Due to the flow drop observed during the cylinder consumption, a flow >60 L/min should be set when helmet-CPAP is started. Considering the flow drop phenomenon, the estimated duration of the tank runtime can be used with a margin of safety when planning patient transport.

Evaluation and Performance of a Positive Airway Pressure Device (CPAP-AirFlife™): A Randomized Crossover Non-Inferiority Clinical Study in Normal Subjects

Background and Objectives: During the COVID-19, the demand for non-invasive ventilatory support equipment significantly increased. In response, a novel non-invasive ventilatory support model called CPAP-AirFlife™ was developed utilizing existing technologies. This model offers technological advantages, including an aerosol-controlled helmet suitable for high-risk environments such as ambulances. Additionally, it is cost-effective and does not require medical air, making it accessible for implementation in low-level hospitals, particularly in rural areas. This study aimed to assess the efficacy of CPAP-AirFlife™ by conducting a non-inferiority comparison with conventional ventilation equipment used in the Intensive Care Unit. Materials and Methods: A clinical study was conducted on normal subjects in a randomized and sequential manner. Parameters such as hemoglobin oxygen saturation by pulse oximetry, exhaled PCO2 levels, vital signs, and individual tolerance were compared between the CPAP-AirFlife™ and conventional equipment. The study population was described in terms of demographic characteristics and included in the analysis. Results: It was shown that the CPAP-AirFlife™ was not inferior to conventional equipment in terms of efficacy or tolerability. Hemoglobin oxygen saturation levels, exhaled PCO2 levels, vital signs, and individual tolerance did not significantly differ between the two models. Conclusions: The findings suggest that CPAP-AirFlife™ is a practical and cost-effective alternative for non-invasive ventilatory support. Its technological advantages, including the aerosol-controlled helmet, make it suitable for high-risk environments. The device's accessibility and affordability make it a promising solution for implementation in low-level hospitals, particularly in rural areas. This study supports using CPAP-AirFlife™ as a practical option for non-invasive ventilatory support, providing a valuable contribution to respiratory care during the COVID-19 pandemic and beyond.

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.

An aquarium air pump, few plastic tubes, and a tight-fitting mask can be used to form an improvised continuous positive airway pressure (CPAP) device that could be lifesaving for many in low-resource countries. Although the device seems promising, further research is needed to establish its safety and efficacy.

The LeVe CPAP System for Oxygen-Efficient CPAP Respiratory Support: Development and Pilot Evaluation

Background: The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has placed a significant demand on healthcare providers (HCPs) to provide respiratory support for patients with moderate to severe symptoms. Continuous Positive Airway Pressure (CPAP) non-invasive ventilation can help patients with moderate symptoms to avoid the need for invasive ventilation in intensive care. However, existing CPAP systems can be complex (and thus expensive) or require high levels of oxygen, limiting their use in resource-stretched environments. Technical Development + Testing: The LeVe ("Light") CPAP system was developed using principles of frugal innovation to produce a solution of low complexity and high resource efficiency. The LeVe system exploits the air flow dynamics of electric fan blowers which are inherently suited to delivery of positive pressure at appropriate flow rates for CPAP. Laboratory evaluation demonstrated that performance of the LeVe system was equivalent to other commercially available systems used to deliver CPAP, achieving a 10 cm H2O target pressure within 2.4% RMS error and 50-70% FiO2 dependent with 10 L/min oxygen from a commercial concentrator. Pilot Evaluation: The LeVe CPAP system was tested to evaluate safety and acceptability in a group of ten healthy volunteers at Mengo Hospital in Kampala, Uganda. The study demonstrated that the system can be used safely without inducing hypoxia or hypercapnia and that its use was well-tolerated by users, with no adverse events reported. Conclusions: To provide respiratory support for the high patient numbers associated with the COVID-19 pandemic, healthcare providers require resource efficient solutions. We have shown that this can be achieved through frugal engineering of a CPAP ventilation system, in a system which is safe for use and well-tolerated in healthy volunteers. This approach may also benefit other respiratory conditions which often go unaddressed in Low and Middle Income Countries (LMICs) for want of context-appropriate technology designed for the limited oxygen resources available.

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.

The efficacy of the WhisperFlow CPAP system versus high flow nasal cannula in patients at risk for postextubation failure: A Randomized controlled trial

PURPOSE

Compare the efficacy(reintubation rate) between a high-flow nasal cannula(HFNC) and the WhisperFlow CPAP system in patients at risk for postextubation failure.

MATERIAL AND METHODS

RCT was conducted in patients who had at least one high-risk criterion for postextubation failure. All patients were randomly assigned to CPAP or HFNC for 48 h.

RESULTS

Of 140 patients, sixty-nine were assigned to the CPAP group and 71 to the HFNC group. The reintubation rate was similar between the HFNC and WhisperFlowCPAP [5 cases(7.0%) vs. 6 cases(8.7%); P = 0.76]. The postextubation respiratory failure rate was not significantly different between the HFNC and WhisperFlow CPAP groups [10 cases(14.1%)vs.7cases(10.1%); P = 0.48]. The respiratory rate was lower in the HFNC than CPAP group(P = 0.04). The pain rating scale score was lower in the HFNC group than in the WhisperFlow CPAP group at 24 h (2.8 ± 2.0 vs. 3.7 ± 1.9, P = 0.02) and 48 h (2.8 ± 1.8 vs. 3.8 ± 1.9, P = 0.002).

CONCLUSIONS

We are unable to demonstrate a reduction in postextubation respiratory failure in at risk patients with the use of HFNC compared with the WhisperFlow CPAP system probably because small sample size, but HFNC was better tolerated.

Fisioterapia respiratória associada à pressão positiva nas vias aéreas na evolução pós-operatória da cirurgia bariátrica

Analisar volume corrente (VC), volume minuto (VM) e frequência respiratória (FR) de obesas mórbidas no pós-operatório de cirurgia bariátrica (CB), após a fisioterapia respiratória convencional (FRC) associada ou não à pressão positiva contínua nas vias aéreas (CPAP) no pré-operatório. Foram estudadas 36 mulheres, com idade de 40,1±8,41 anos, que seriam submetidas à CB por laparotomia e que realizaram FRC (exercícios respiratórios diafragmáticos, de inspirações profundas, fracionadas e associados a movimentos de membros superiores, 1 série de 10 repetições de cada exercício) por 30 dias antes da cirurgia. Após internação, 18 delas foram submetidas a 20 minutos de CPAP, 1 hora antes da indução anestésica e compuseram o grupo FRC+CPAP. As outras 18 não receberam o CPAP e compuseram o grupo FRC. Foram avaliados VM, VC e FR por meio do ventilômetro, no momento da internação e 24 horas após a realização da cirurgia. Constatou-se que as medidas de VC, VM e FR não apresentaram significância estatística quando comparados os resultados do pré e pós-operatório em ambos os grupos, bem como quando comparados os dois grupos entre si tanto no pré como no pós-operatório. Os resultados sugerem que a tanto a aplicação da FRC como a aplicação da FRC+CPAP no período pré-operatório contribui para a manutenção das variáveis respiratórias no pós-operatório. A aplicação do CPAP antes da indução anestésica não promoveu benefícios adicionais no pós-operatório de CB no que se refere aos volumes pulmonares.

CPAP for acute cardiogenic pulmonary oedema from out-of-hospital to cardiac intensive care unit: a randomised multicentre study

PURPOSE

Continuous positive airway pressure (CPAP) is a useful treatment for patients with acute cardiogenic pulmonary oedema (CPE). However, its usefulness in the out-of-hospital setting has been poorly investigated and only by small and single-centre studies. We designed a multicentre randomised study to assess the benefit of CPAP initiated out of hospital.

METHODS

A total of 207 patients with CPE were randomly allocated by emergency mobile medical units to receive either standard treatment alone or standard treatment plus CPAP. CPAP was maintained after admission to the intensive care unit (ICU). Inclusion criteria were orthopnoea, respiratory rate greater than 25 breaths/min, pulse oximetry less than 90% in room air and diffuse crackles. The primary end point was assessed during the first 48 h and combined: death, presence of intubation criteria, persistence of either all inclusion criteria or circulatory failure at the second hour or their reappearance before 48 h. Absence of all criteria defined successful treatment.

RESULTS

CPAP was used for 60 min [40, 65] (median [Q1, Q3]) in the pre-hospital setting and 120 min [60, 242] in ICU and was well tolerated in all patients. Treatment was successful in 79% of patients in the CPAP group and 63% in the control group (p = 0.01), especially for persistence of inclusion criteria after 2 h (12 vs. 26%) and for intubation criteria (4 vs. 14%). CPAP was beneficial irrespective of the initial PaCO(2) or left ventricular ejection fraction.

CONCLUSION

Immediate use of CPAP in out-of-hospital treatment of CPE and until CPE resolves after admission significantly improves early outcome compared with medical treatment alone.