What are Clinical Ventilators and Their Challenges?

[Lnewqban]

My apologies if already posted here or somewhere else.

These articles are about what a clinical ventilator is, what problems improper use can cause and what parts are some people creating by 3-D printing:

https://en.wikipedia.org/wiki/Ventilator

https://en.wikipedia.org/wiki/Bag_valve_mask

https://www.fastcompany.com/9047794...ives-by-making-new-respirator-valves-for-free

https://hackaday.com/2020/03/12/ult...-design-and-deploy-an-open-source-ventilator/

 

[berkeman]

what problems improper use can cause

What do you think the main problems might be?

 

[hutchphd]

I think everyone is thinking about ways that we can slightly forestall this impending human tragedy in the USA . One thought I had was whether some of the home CPAP machines could be used as ventilation aids prior to possible intubation with the associated risks. There must be several million of these extant in the US I note that the typical overpressure are measured in inches of H2O and so are very small indeed. I know that only a few feet of surfacing with a full lung can get a scuba diver into trouble ( embolus or otherwise).
Is there any utility for CPAP in this present potential shortfall? Is there something short term to be done?. I feel woefully ignorant here.

 

[Lnewqban]

What do you think the main problems might be?

I just started exploring this subject.
The second link shows that accidental excess of pressure can do a lot of damage to the lung tissue, reason for which modern machines must have sophisticate systems of monitoring and control, not only of supply pressure, but humidity, volume, percentage of mixed oxygen, etc.

"Under normal breathing, the lungs inflate under a slight vacuum when the chest wall muscles and diaphragm expand; this "pulls" the lungs open, causing air to enter the lungs to inflate under a gentle vacuum. However, when using a manual resuscitator, as with other methods of positive-pressure ventilation, the lungs are force-inflated with pressurized air or oxygen. This inherently leads to risk of various complications, many of which depend on whether the manual resuscitator is being used with a face mask or ET tube. Complications are related to over-inflating or over-pressurizing the patient, which can cause: (1) air to inflate the stomach (called gastric insufflation); (2) lung injury from over-stretching (called volutrauma); and/or (3) lung injury from over-pressurization (called barotrauma)."

From a conversation with a doctor, I have learned that the virus compromises normal functioning of lungs and heart, leading to opportunistic bacterial infections.
When the patient has difficulty breathing by his/her own muscular action, and/or when the surface of blood-air exchage is severely reduced, an external mask is not enough to induce positive ventilation (mixed with oxygen) and that an ET tube is frequently used.

 

[Stephen Tashi]

Ventilators in hospitals have several "modes" of operation. https://www.openanesthesia.org/modes_of_mechanical_ventilation/

 

[hutchphd]

Here's another ignorant question: do any of the techniques use "snorkle" mouthpiece (with maybe nose clip) instead of facemask?. It would seem to require less manual intervention and supervision.

 

[jim mcnamara]

Ventilated patients require lots of intervention and monitoring - why you "see" and hear the audible beep-beep.

 

[Stephen Tashi]

Ventilated patients require lots of intervention and monitoring - why you "see" and hear the audible beep-beep.

Also, patients continuously on ventillators must be fed through tubes. They can't drink water so they usually get fluid through an IV.

It isn't clear to me how being on ventillator affects a patients lucidity. I suppose many ventillator patients are not lucid due to disease. However, I think most ventillator patients are also given tranquilizers and pain killers. A half awake patient may attempt to tear the mask and tubes away. In the USA, physically restraining a patient's arms to prevent this is a big bureaucratic deal, so drugs are the first resort.

 

[hutchphd]

My thought was trying to use some level of breathing assistance intermediate between intubation (which has a host of issues) and facemask (which requires constant monitoring if not direct manual application for efficacy). Hence the idea of a scuba/snorkel mouthpiece. Does any system use this?

This intervention hopefully could take place before the onset of respiratory collapse so the patient might still be cognizant enough to respond appropriately. I have done a lot of medical R&D but very little clinical so this may be foolishness.

With regard to regs...these are not quite desperate times. A luxury that hopefully we can and will continue.

 

[dlgoff]

Ventilated patients require lots of intervention and monitoring - why you "see" and hear the audible beep-beep.

I thought this YouTube video may be useful.