A medical ventilator to help Covid-19 patients breathe has been granted regulatory approval, meaning hundreds could be rolled out to hospitals from next week. Penlon’s ESO2 device, developed under the codename Project Oyster, will become the first model to get the green light from the Medicines and Healthcare Products Regulatory Agency (MHRA), with an announcement expected as soon as Thursday. Formal approval comes amid mounting concern that tens of thousands of ventilators ordered by the government are still awaiting regulatory clearance. The length of the process has stoked fears about the readiness of the NHS for a surge in patients requiring ventilation. The health secretary, Matt Hancock, has said the government wants to increase ventilator stocks from 10,000 to 18,000 to be sure of having enough. The government had placed a provisional order for 5,000 of the ESO2 ventilators from the Oxfordshire-based Penlon, which is part of the Ventilator Challenge UK consortium involving manufacturers such as Airbus and Rolls-Royce. The larger firms have lent their manufacturing muscle to help scale up production of Penlon’s existing ESO2 model. The order was conditional on MHRA sign-off because, while the ESO2 is a proven ventilator, it had to be tweaked slightly to allow it to be mass-produced. It also had to be updated after the government altered the specifications given to companies offering to build the machines. The new requirements mean the devices must be easy to switch on and off regularly so that fluid can be drained from patients’ lungs, something that can be necessary on an hourly basis with Covid-19. The added criterion has forced the cancellation of one ventilator project, BlueSky, involving the Formula One teams Aston Martin Red Bull and Renault. But Penlon is understood to have revised its design swiftly to meet the updated guidelines. Several dozen of its ESO2 devices are already in hospitals around the country, where they have been undergoing clinical trials. But the formal approval on Tuesday evening means that Penlon is expected to ramp up production immediately, and could roll out hundreds of machines next week backed by Ventilator Challenge UK members. Consortium member Airbus has replicated Penlon’s production line at the Advanced Manufacturing Research Facility in north Wales, next to the Broughton site where it makes wings for jet aircraft. Ventilator Challenge UK has said it could be producing 1,500 ventilators a week by early May, including a separate model, the paraPac designed by Luton-based Smiths Medical. Some paraPacs have arrived at hospitals, but they are primarily intended for short-term use during patient transport. The Guardian approached Ventilator Challenge UK for comment on Tuesday evening but had not received a response by the time of publication.