CPAP use for Coronavirus mitigation & severe pneumonia

[DeepBreathing]

Are there any program overrides that can help us with controlling breathing for a user under these extreme situations?

That depends entirely on what sort of CPAP you have. Basic fixed pressure and APAP machines do not control the rate of breathing, but bilevel machines with backup do. I don't think I've seen a bilevel PAP machine with a backup rate in the range you're quoting.

A lot of people have suggested that the PAP machine manufacturers should provide firmware upgrades and support DIY methods of using PAP machines as ventilators. I suspect they are working absolutely flat out to produce hospital style ventilators as fast as possible. Research & development is likely looking at ways of producing these faster, and working with other manufacturing industries (eg car makers) to get them up to speed with ventilators. I expect that supporting DIY efforts is probably very low on their priorities list.

[srlevine1]

Tis a shame we don't know how to up the pressure...

That is the kind of statement or idea that might stimulate someone with a bit of knowledge on CPAP mechanics into thinking, "Wait a minute,  I think that actually might be possible".

We simply never know, folks.  Good comment, Dave.  

(Moderator: If this has been previously posted or needs to be placed in another thread, please delete or change its location.)

The FDA recognized the use of CPAP equipment if ventilators or not available or the patient's condition is mild.

Ventilator Supply Mitigation Strategies: Letter to Health Care Providers
 
The U.S. Food and Drug Administration (FDA) recognizes that the need for ventilators, ventilator accessories, and other respiratory devices may outpace the supply available to health care facilities during the Coronavirus Disease 2019 (COVID-19) outbreak.

On March 22, 2020, the FDA issued an immediately in effect guidance outlining a policy intended to help increase availability of ventilators and their accessories as well as other respiratory devices during the COVID-19 pandemic. For details, see Enforcement Policy for Ventilators and Accessories and Other Respiratory Devices During the Coronavirus Disease-2019 (COVID-19) Public Health Emergency. The policy fosters the continued availability of certain safe and effective medical devices while being flexible regarding manufacturer modifications made to ventilators, anesthesia gas machines and other respiratory devices, and their accessories, in response to the COVID-19 public health emergency.

This Letter provides recommendations for health care providers and facilities, based on the recently issued guidance, regarding the use of devices with patients who develop respiratory compromise from COVID-19 or other respiratory disorders.  The FDA's recommendations are intended to augment, not replace, specific controls and procedures developed by health care organizations and the Centers for Disease Control and Prevention (CDC). 

Recommendations

The FDA recommends health care providers and facilities, wherever possible:

Use FDA-cleared conventional/standard full-featured ventilators when available to support patients with respiratory failure.

Under the policy, manufacturers may make certain modifications to FDA-cleared indications, claims, or functionality of these devices, without prior submission of a premarket notification where the modification will not create an undue risk in light of the public health emergency. In such circumstances, FDA recommends that the manufacturer provide clear instructions delineating FDA-cleared indications and claims from those that are not FDA-cleared, in addition to a general statement about changes that have not been cleared by FDA.

If the number of ventilators in your facility is running low, consider alternative devices capable of delivering breaths or pressure support to satisfy medically necessary treatment practices for patients requiring such ventilatory support. Health care providers should use their judgment based on the condition of the patient and the circumstances in the facility to choose the best option. Examples of alternative uses of respiratory devices used to address shortages might include the following, which the FDA believes may help increase availability:

For any patient needing ventilatory support, continuous ventilators labeled for home use may be used in a medical facility setting depending on the features of the ventilator and provided there is appropriate monitoring (as available) of the patient's condition.

For stable patients, emergency transport ventilators may be used for prolonged ventilation in a medical facility setting.

For any patient needing ventilatory support, anesthesia gas machines capable of providing controlled ventilation or assisted ventilation may be used outside of the traditional use for anesthetic indication. Because of significant differences between the anesthesia gas machine and traditional critical care ventilators, use or supervision by an anesthesia provider is recommended. Refer to the manufacturers' websites for specific instructions on safe use of anesthesia gas machines for this indication.

Noninvasive Ventilation (NIV) Patient Interfaces capable of prescribed breath may be used for patients requiring such ventilatory support, including NIV Patient Interfaces labeled for sleep apnea.

Continuous Positive Airway Pressure (CPAP), auto-CPAP, and bilevel positive airway pressure (BiPAP or BPAP) machines typically used for treatment of sleep apnea (either in the home or facility setting) may be used to support patients with respiratory insufficiency provided appropriate monitoring (as available) and patient condition.

Take appropriate precautions with environmental control (for example, negative pressure) or additional filtration where feasible: Ventilating patients with communicable diseases using devices that are single limb or noninvasive without a filtered seal from atmosphere may contaminate the room air and increase risk of transmission. This risk may be exacerbated by high-flow nasal cannula systems or CPAP machines.

Contact the device manufacturer or review the manufacturer website for guidance on updated labeling: If using a ventilator, gas machine, or other device outside of its labeled indications, FDA recommends contacting the device manufacturer for information on the features and limitations of the device in an emergency use situation.
Contact the appropriate professional societies for up-to-date information: For recently issued useful information relevant to this issue.

The letter can be found on the FDA's website. Ventilator Supply Mitigation Strategies: Letter to Health Care Providers

[gctam65]

Hi All,

I live in Calgary, Alberta and here is an interesting article about a couple of local university professors building a ventilator prototype using shop vac and a Home Depot bucket:

Please google "Calgary Herald ventilator prototype" as I am new here and this is my first post so do not have 4 posts yet allowing me to post links.


The article also mentioned that "The negative pressure system does have advantages over the now-more-typical positive pressure devices because they don’t obstruct the patients’ face, they said."

I am not sure if the professors would share a schematic of their prototype but does anyone have ideas of building something similar or modifying CPAP machines using household parts to achieve the same result?

Garry

[DeepBreathing]

Thanks Garry, and welcome to Apnea Board.

What these guys have produced is an updated version of the old iron lung, where the patient lies in a sealed tube and pressure is cycled to expand and contract the lungs. In this case they're using a form-fitting polyethylene body shell, which will probably be the hardest thing for a DIYer to reproduce. There's also no detail on the pressure cycling valve, other than to say it's made of household parts. This could work but we need more details, please Professors.

[miffed]

This topic was covered by NPR today, but I guess I can't post a link because I haven't posted before.

The article title is "CPAP Machines Were Seen As Ventilator Alternatives, But Could Spread COVID-19"

https://npr.org/sections/health-shots/20...822211604/

[jbourne]

What do ventilators do with the exhaled air, in order to avoid aerosol contaminating the room? 
I use HEPA room filters. They should help I would imagine. But, would it be sufficient?
Additionally, someone suggested exhaling through a liquid disinfectant which should be doable.

I'm also getting overwhelmed by the number of options: CPAP, APAP, BiPaP, VPAP, etc. 
After looking for a couple of days, not sure I'm able to identify the minimal but safe setup. 
I'm thinking things like auto adjustment, sleep quality, comfort aren't that much of a priority(unlike in the case of sleep apnea), just as long as safety is ensured and it fulfills the basic purpose for a few days.

[DeepBreathing]

What do ventilators do with the exhaled air, in order to avoid aerosol contaminating the room?

The exhaled air passes through a filter in the ventilator before being expelled back into the room. I would guess they are pretty high-specification filters.

I'm also getting overwhelmed by the number of options: CPAP, APAP, BiPaP, VPAP, etc.

That's part of the problem we have. In this extreme hopefully hypothetical situation we won't have the option of running out and getting an ASV or VPAP, we'll just have to make the best use of whatever machine we have. It's a case of something is better than nothing.

[stephen N]

A home-made air sterilization unit might look like a water-pipe.  The exhalation air would bubble into a liquid bath before it is released into the atmosphere. The liquid bath might be a bleach solution ((even an acid bath??))  (suggestions should come from virus control medical experts). 

Another problem, the input  air that the patient is given should also be free of the virus, this seems like  a bigger challenge within a hospital crowded with corvid-19 patients. The inhalation air might be sterilized with filters and a SAFE non toxic sterilization unit, maybe with ultraviolet light.

No idea if it is myth or proven - but I hear that covid-19 virus is rapidly killed when it comes in contact with a copper surface.

 If so, it wouldn't be hard to make a pair of canisters packed with copper mesh or similar [copper scouring pads] with both the intake air and exhaled air passing through their own canisters.
If U.V. light is effective at killing the virus as well, it wouldn't be that hard to include this into both sides of the system too.
The beauty of this is that everything is "off the shelf" at your hardware store and supermarket.

[arhdc]

Much of the standard hardware should be physically capable of much more than the programming allows.

A Resmed Lumis (S9) TX can be set to pressures of 30cmH2O and a respiration rate of 8-50 in PAC mode. ResMed markets the Lumis Tx is an all-in-one hospital noninvasive ventilator. Physically it looks just like a regular S9 with the addition of an alarm module. I doubt there is much, if any, difference in the hardware, from a regular S9 autoset. All of the differences are software. Based on this it should be possible to make almost any autoCPAP capable of more modes with software or control module upgrades. I was very skeptical that these kinds of upgrades would be developed or offered a few days ago, I am less skeptical now in light of the efforts that are being made to produce ventilators from scratch.

[dbainbr]

Two xPAPS in series:

Some have asked about ganging two PAPa in series, and how they measure pressure. Others have indicated WHO CARES, most of us don't have two anyway. I say most of us don't have biPAPs either, but those who do are interested in how best to use them. I wish I had a biPAP, too, but I don't. However I DO have both a CPAP and an APAP, so here's the result of my testing:

As I would have bet, they use gauge pressure, the same as our lungs. Mine are both ResMed 10 variations, but this should apply to all.

Therefore, feeding the output of my CPAP into the input of my APAP did not make the pressure at the mask go up, unless the CPAP pressure was set higher than the APAP minimum pressure setting.

However, feeding the output of my CPAP into a big ziplock bag containing my APAP DID make the pressure at the mask go higher, so if I desperately wanted more pressure I's do that

Now we just need to figure out WHAT pressure we want, the higher pressure that a ventilator CAN reach, or lower pressure to prevent further damage to the alveoli.

Until we figure out more, my plan is to leave my settings where they are. Mine are higher than most, at 12 cmH2O for the low setting, and 20 for the upper limit (neither my old CPAP, nor the newer APAP can be set higher than 20).