3 ms·

I thought I remembered reading somewhere recently that 2:1 is already in use in some cases (maybe in Italy?), but I can't find a source. Is there increased ris

I thought I remembered reading somewhere recently that 2:1 is already in use in some cases (maybe in Italy?), but I can't find a source. Is there increased risk of ventilator failure with this approach? That seems like it could be an additional terrible factor to weigh, because parts have become so scarce.

froindt 7y ago
The article makes it sound like the ventilators have a wide enough range of operation to accommodate. It may not work for the tail end (set of 4 people each with large lung capacity), but could work for many.
pzlarsson 7y ago
The 2:1 setup was used to save lives after a mass shootings in Las Vegas a few years ago. They paired patiets of similar size, put them on the same ventilator and double the flow rate. It was mentioned in a blog post by an ER physician linked from hn back then.
- enchiridion 7y ago
  The article for the interested. It's a tough but good read. https://epmonthly.com/article/not-heroes-wear-capes-one-las-vegas-ed-saved-hundreds-lives-worst-mass-shooting-u-s-history/ https://epmonthly.com/article/not-heroes-wear-capes-one-las-...
gizmo686 7y ago
I spoke with a father (a pulmonary and critical care doctor) about this. Based on the specs, he estimates that a single ventilator could support up to 4 patients [0]. The bigger issue is the control system. Ideally, a ventilator will allow the patient to decide when to breath, and provide assistance; only forcing a breath when the patient fails to breath at all. WIth multiple patients, this is impossible, and you are forced to use continuous mandatory ventilation mode, where the ventilator cycles air pressure at a constant pattern regardless of what the patient is doing. Modern ventilators do not even support such a mode; although it can be emulated by programming the ventilator such that it would never detect a breath. Another issue is doctor error. When programming a ventilator you can either program it in terms of air-flow or pressure. With multiple patients, programming in terms of air-flow is almost certainly wrong, and would cause a change in condition of one patient to negatively effect the treatment of all attached patients. This problem goes away with pressure based controls. However, if you have doctors who are used to using flow based controls, and are overworked, while using a novel treatment method, I would expect to see accidents where they either continue to use flow-based controls, or do switch to pressure based but are less effective at it due to it being yet another change from their normal practice. Another downside is that all patients attached to the same ventilator need the same settings. You could potentially mitigate this cheaply by using analog pressure step-downs on the valves, but this just compounds the above problems, and introduces even more room untested elements to the equation. [0] The exact number depends on how much airflow you want to provide. Apparently, in cases such as this, you actually want to provide relatively little airflow to avoid further damaging the lungs by over-inflating them.

froindt 7y ago

The article makes it sound like the ventilators have a wide enough range of operation to accommodate. It may not work for the tail end (set of 4 people each with large lung capacity), but could work for many.

pzlarsson 7y ago

The 2:1 setup was used to save lives after a mass shootings in Las Vegas a few years ago. They paired patiets of similar size, put them on the same ventilator and double the flow rate. It was mentioned in a blog post by an ER physician linked from hn back then.

enchiridion 7y ago
The article for the interested. It's a tough but good read. https://epmonthly.com/article/not-heroes-wear-capes-one-las-vegas-ed-saved-hundreds-lives-worst-mass-shooting-u-s-history/ https://epmonthly.com/article/not-heroes-wear-capes-one-las-...

gizmo686 7y ago

I spoke with a father (a pulmonary and critical care doctor) about this. Based on the specs, he estimates that a single ventilator could support up to 4 patients [0]. The bigger issue is the control system. Ideally, a ventilator will allow the patient to decide when to breath, and provide assistance; only forcing a breath when the patient fails to breath at all. WIth multiple patients, this is impossible, and you are forced to use continuous mandatory ventilation mode, where the ventilator cycles air pressure at a constant pattern regardless of what the patient is doing. Modern ventilators do not even support such a mode; although it can be emulated by programming the ventilator such that it would never detect a breath. Another issue is doctor error. When programming a ventilator you can either program it in terms of air-flow or pressure. With multiple patients, programming in terms of air-flow is almost certainly wrong, and would cause a change in condition of one patient to negatively effect the treatment of all attached patients. This problem goes away with pressure based controls. However, if you have doctors who are used to using flow based controls, and are overworked, while using a novel treatment method, I would expect to see accidents where they either continue to use flow-based controls, or do switch to pressure based but are less effective at it due to it being yet another change from their normal practice. Another downside is that all patients attached to the same ventilator need the same settings. You could potentially mitigate this cheaply by using analog pressure step-downs on the valves, but this just compounds the above problems, and introduces even more room untested elements to the equation. [0] The exact number depends on how much airflow you want to provide. Apparently, in cases such as this, you actually want to provide relatively little airflow to avoid further damaging the lungs by over-inflating them.