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

Abstract

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.

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“…In this regard, it is required to evaluate the degree of distinctiveness which in this study is determined using the HTMT ratio. The study carried out by Brown (2015) opined that the value of the HTMT ratio should be below 0.9 as a liberal criterion of discriminant validity. In this concern, the results have been presented in Table 2.…”

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“…Continuous Positive Airway Pressure (CPAP) to minimize oxygen consumption, along with a decrease in air contamination by COVID-19 pathogens and noise [56]. Their proposed NIV-CPAP system includes the automatic control of patients' respiratory parameters.…”

“…Dispensation optimization of medical oxygen supply, in its simplest form, involves reducing unwanted consumption. With this goal in mind, Cavaglià et al proposed a closed-circuit noninvasive (NIV) continuous positive airway pressure (CPAP) to minimize oxygen consumption, along with a decrease in air contamination by COVID-19 pathogens and noise [48]. Their proposed NIV-CPAP system included automatic control of patients' respiratory parameters.…”