Summary Background The manufacturing of any standard mechanical ventilator cannot rapidly be upscaled to several thousand units per week, largely due to supply chain limitations. The aim of this study was to design, verify and perform a pre-clinical evaluation of a mechanical ventilator based on components not required for standard ventilators, and that met the specifications provided by the Medicines and Healthcare Products Regulatory Agency (MHRA) for rapidly-manufactured ventilator systems (RMVS). Methods The design utilises closed-loop negative feedback control, with real-time monitoring and alarms. Using a standard test lung, we determined the difference between delivered and target tidal volume (VT) at respiratory rates between 20 and 29 breaths per minute, and the ventilator’s ability to deliver consistent VT during continuous operation for >14 days (RMVS specification). Additionally, four anaesthetised domestic pigs (3 male-1 female) were studied before and after lung injury to provide evidence of the ventilator’s functionality, and ability to support spontaneous breathing. Findings Continuous operation lasted 23 days, when the greatest difference between delivered and target VT was 10% at inspiratory flow rates > 825 mL/s. In the pre-clinical evaluation, the VT difference was -1 (-90 to 88) mL [mean (LoA)], and positive end-expiratory pressure (PEEP) difference was -2 (-8 to 4) cmH 2 O. VT delivery being triggered by pressures below PEEP demonstrated spontaneous ventilation support. Interpretation The mechanical ventilator presented meets the MHRA therapy standards for RMVS and, being based on largely available components, can be manufactured at scale. Funding Work supported by Wellcome/EPSRC Centre for Medical Engineering,King’s Together Fund and Oxford University.
【저자키워드】 COVID-19, Critical care, biomedical engineering, SBP, systolic blood pressure, Hb, Haemoglobin, Respiration (artificial), ASV, assisted spontaneous ventilation, CO, cardiac output, CRS, respiratory system compliance, DBP, diastolic blood pressure, FIO2, Fraction of inspired oxygen, HR, heart rate, LoA, limits of agreement, MAP, mean arterial pressure, PaCO2, arterial partial pressure of carbon dioxide, PADP, pulmonary artery diastolic pressure, PaO2, arterial partial pressure of oxygen, PASP, pulmonary artery systolic pressure, PEEP, positive end-expiratory pressure, PIP, proportional integral derivative, PFR, PaO2: FIO2 ratio, RAW, airways resistance, SaO2, arterial oxygen saturation, Texp, expiratory time, Tinsp, inspiratory time, VCV, volume controlled ventilation, VT, tidal volume, 【초록키워드】 therapy, Ventilation, lung, Lung injury, Medicine, female, breath, mechanical ventilator, work, university, funding, Evidence, respiratory rate, PEEP, Positive end-expiratory pressure, Support, Volume, Real-time monitoring, ventilator, Oxford, components, product, MHRA, finding, component, limitations, required, provided, supported, demonstrated, triggered, anaesthetised, Continuous, inspiratory flow, meet, 【제목키워드】 ventilator,