A modification to the Maquet Flow-i anaesthesia machine for ICU ventilation

Andrew J Robinson; William London; Lazslo Kotan; Warwick Downing

Operating Room environment to provide short-term ventilation and delivery of volatile anaesthetic gases to patients undergoing general anaesthesia. There are some 7000 such units installed worldwide. The machine is based in part on ventilator technology that Getinge Group purchased from Siemens and is substantially similar in function to the Maquet Servo-i Intensive Care ventilator (Getinge, 2020b) . Modern intensive care ventilators are 'total loss' systems, in that the gases supplied to the breathing system are filtered through a High Efficiency Particulate Air (HEPA) filter then passively expelled to atmosphere after use. The Flow-i anaesthesia machine, however (and in common with other such machines), is designed to allow the expiratory gases to be recirculated with CO2 scavenging in 'low flow' mode with minimal losses to atmosphere. This 'partial loss' system allows preservation of expensive and environmentally damaging volatile anaesthetic gases and lowers consumption of piped oxygen and air. It does this by directing all expired air internally through a Volume Reflector, a convoluted reservoir that sits under the anaesthetist's writing surface that collects the . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.