5 ms·

> Maybe in the form of a cuff that you clamp over someone's wrist that can use computer vision to identify veins and automatically insert the needles and run th

> Maybe in the form of a cuff that you clamp over someone's wrist that can use computer vision to identify veins and automatically insert the needles and run the machine. There's a reason they put the lines in the femoral vessels - these cannulas are like hosepipes - you need to access the large vessels to get sufficient blood flow through the whole circulation.

Scoundreller 7y ago
But if you're going to have 1 machine, you need to build it big enough to get enough flow for recovery. And once you install that hosepipe, why bother changing. The amount of flow needed to only sustain someone that hasn't been severely deoxygenated must be a lot less. A smaller system might be able to initially infuse an oxygen-carrying booster (as Tour de France cyclists do) to get away with lower flow rates.
- rscho 7y ago
  Actually, reducing it much while keeping the current functioning principle would be difficult. ECMO not only oxygenates, but pumps to assist the heart. Red blood cells would not resist infusion through small cannulas at high speed. Hemolysis already is a problem with the current size femoral cannulas. So if what you're after is flow, size is a severe limitation.
  - mikecsh 7y ago
    Indeed - see Poiseuilles equation [https://www.openanesthesia.org/poiseuilles_law_iv_fluids/ https://www.openanesthesia.org/poiseuilles_law_iv_fluids/]
    - rscho 7y ago
      Blood is non Newtonian. Poiseuilles doesn't really apply. I'm aware that's what's taught in med school, though. At the maroscopic level, it works ok.
- robocat 7y ago
  Remember that the system also needs to remove CO2. Severe hypercapnia symptoms are bad.
flyGuyOnTheSly 7y ago
During a full on cardiac arrest, even getting a small trickle of oxygen to the brain for a few extra minutes can be life altering.
- mikecsh 7y ago
  During a cardiac arrest the primary problem is a pump failure - blood is not flowing through the vasculature. A trickle of oxygen into the wrist will not help if the blood is not being circulated.

Scoundreller 7y ago

But if you're going to have 1 machine, you need to build it big enough to get enough flow for recovery. And once you install that hosepipe, why bother changing. The amount of flow needed to only sustain someone that hasn't been severely deoxygenated must be a lot less. A smaller system might be able to initially infuse an oxygen-carrying booster (as Tour de France cyclists do) to get away with lower flow rates.

rscho 7y ago
Actually, reducing it much while keeping the current functioning principle would be difficult. ECMO not only oxygenates, but pumps to assist the heart. Red blood cells would not resist infusion through small cannulas at high speed. Hemolysis already is a problem with the current size femoral cannulas. So if what you're after is flow, size is a severe limitation.
- mikecsh 7y ago
  Indeed - see Poiseuilles equation [https://www.openanesthesia.org/poiseuilles_law_iv_fluids/ https://www.openanesthesia.org/poiseuilles_law_iv_fluids/]
  - rscho 7y ago
    Blood is non Newtonian. Poiseuilles doesn't really apply. I'm aware that's what's taught in med school, though. At the maroscopic level, it works ok.
robocat 7y ago
Remember that the system also needs to remove CO2. Severe hypercapnia symptoms are bad.

flyGuyOnTheSly 7y ago

During a full on cardiac arrest, even getting a small trickle of oxygen to the brain for a few extra minutes can be life altering.

mikecsh 7y ago
During a cardiac arrest the primary problem is a pump failure - blood is not flowing through the vasculature. A trickle of oxygen into the wrist will not help if the blood is not being circulated.