[Mz]

There are multiple articles readily found about complications of using positive pressure:

https://www.medscape.com/viewarticle/581344_7

http://www.mdedge.com/ecardiologynews/dsm/5224/hospital-medi...

https://www.ncbi.nlm.nih.gov/pubmed/2199002

To my mind, this is actually related:

https://www.energyvanguard.com/blog/54084/Why-I-m-Not-a-Fan-...

One of the problems you run into with any lung related mechanical devices is the need for proper sterilization. From what I gather, this is much less of an issue with negative pressure ventilation.

People in iron lungs are people with fundamentally compromised immune systems. Exposing them to germs forced into their lungs by positive pressure while potentially damaging their lung tissues in the process strikes me as a great way to give them a deadly infection, sooner or later.

[jschwartzi]

Are you sure they are substantially immunocompromised? they're opening and closing their mouths and breathing through their noses on a regular basis while exposed to room air. There is no bacteria filtration like there would be with a properly configured positive pressure ventilator's circuit. The mucous membranes in the airway and nasal passages actually provide a significant amount of filtration themselves, and some circuit configurations are non-invasive which enables these natural filters to function.

There is potential for barotrauma in improperly configured devices, especially with volume-controlled ventilation, but it's possible to configure the device to ventilate safely, otherwise we wouldn't use them. Modern devices do have safety features like high pressure cutoffs and direct pressure controls which can prevent barotrauma. Some of these have to be configured correctly by the clinician for each patient.

Regarding the link to positive pressure HVAC, I'm not sure what that has to do with medical ventilation. HVAC provides a constant flow into a room, but medical ventilation cycles to an inspiratory pressure or inspiratory tidal volume repeatedly either on a patient trigger or on a set timing schedule.

I'm still really curious if there are any Respiratory Therapists or Physicians who can speak to this?

[Mz]

From what I understand, they are partially paralyzed. Every partially paralyzed individual I have personally met was pretty ill, basically. I have a compromised immune system. Being around paralysis victims is a big problem for me.

So, yes, I feel quite confident. Though what I know and what I can prove are very different things.

Edit: I will add that I have come to believe that breathing problems inherently impair the immune system. Oxygen is one of the things the body uses to kill stuff. If you can't breathe, you are pretty vulnerable to microscopic warfare. (Another thing I know but probably can't prove, fwiw.)

[echelon]

You find that paralyzed people are immunocompromised or harbor infections at a greater probability than the general population?

I wonder if this is due to lower rates of lymph circulation, which relies on the body being in motion. The lymphatic system is a key part of the immune system.

[Mz]

Yes, in my experience, they are chronically infected and it is dangerous for me to be around them.

I imagine there are quite a few factors, but I think that is a good thought. Walking a great deal -- sometimes on the order of many hours a day -- has played a large role in my successful efforts to improve my health. I am convinced that moving lymph is a very big part of that.