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I'm an anaesthetics and intensive care trainee, so I know something about ventilation. The reason COVID-19 patients need to get ventilated is due to a failure of oxygenation - the infection causes direct lung injury (ARDS) which impairs oxygen absorption in the lung tissue. Normally we breathe room air, which is 21% oxygen, this drops to around 10% oxygen in the arterial blood due to inefficiencies in the absorption in the lungs. In a normal healthy patient breathing 100% Oxygen, their arterial oxygen content would be around 90%. ARDS significantly impairs oxygen uptake by the lungs, in severe cases patients breathing 100% oxygen may have arterial oxygen concentrations of just 8-10%. The purpose of ventilation in these severe ARDS patients is to augment oxygenation of the blood, using a combination of techniques including end-expiatory positive pressure and inverse-ratio ventilation, among others, and support the fatiguing respiratory muscles. Because the lungs of COVID-19 patients are already injured by the infection, they are very prone to further ventilator-associated injury. Modern intensive care ventilators have complicated computer-controlled 'modes', which allow precise regulation of ventilatory volumes, pressures, rates, timing, and gas blending. The ARDSnet trials in the early 2000s demonstrated the importance of carefully managed 'lung protective' ventilation, poor quality ventilation is likely to cause further lung injury and make the patient worse, not better. Therefore amateur ventilators are unlikely to be beneficial in COVID-19 unless they can provide similar lung protective ventilation, which would make them quite complicated. Additionally, ventilation is just one component of the management of sick COVID-19 patients. First you need to pass a breathing tube into their trachea, which is a challenging and risky procedure when performed by a skilled operative in a otherwise well patient, let alone someone on the brink of respiratory failure. Once intubated you will need to keep them deeply sedated, otherwise they will strain against the ventilator and make effective ventilatory care impossible. This requires equipment, drugs, and skilled staff, all of which are going to be in short supply. |