Creating a plan to reprogram smart CPAP machines to become emergency ventilators
IMPORTANT NOTE: Several people have skimmed this article and gotten the mistaken impression it proposes using CPAP or BiPAP machines to treat patients who need a ventilator, using CPAP masks with open exhaust ports. It does not. It is about converting the hardware currently used for CPAP to be mechanical ventilators, not CPAP, for some patients, in a way very similar to the FDA approved ventilators which may be in very short supply.
As I'm sure, you've heard about the need that many Covid-19 patients have for ventilators which keep them breathing when their lungs fail, as they do during the "ARDS" (acute respiratory distress syndrome) phase of Covid-19 which is the thing that kills you. The problem is that there are at most around 200,000 ventilators (including tapping older models sitting in storage, a government strategic reserve and a military reserve.) It is feared that as many as 900,000 could be needed if the worst projections are true. Around the world, many more.
Companies that make ventilators are ramping up manufacturing as fast as they can. It still won't be enough. That's even true if one applies a special technique devised years ago to put 2, 4 and even 9 patients on the same machine, if the patients can be matched so they need the same pressures, airflow and oxygen. This technique was tested under fire during the Las Vegas massacre and saved hundreds of lives, but it's still only barely tested for something like this -- ARDS patients may need to be on the ventilator for up to a month, if they live.
One tragedy for the ventilator makers -- if they are able to produce hundreds of thousands of their FDA approved modern ventilators, they will save many lives -- but then no hospital, anywhere in the world, will need to buy a new ventilator for years, because there will be such a huge surplus after this is over. Stepping up means a big sales windfall, but then destroying their business, unless some special government intervention comes in. There is much debate if manufacturing at this volume is even possible.
Several interesting projects have sprung up to create designs for cheap ventilators, included from CPAP parts and there's even a contest with a prize. What's even more important than cheap is that they be reliable and that it is possible to make or obtain vast numbers of reliable ones quickly. These range from hacker projects to fully manual ventilators which literally require an attending person to squeeze an air bladder to breathe for the patient. They must do this 24 hours a day, and will be exposing themselves to the virus when they do so. If they let up, if they make a serious mistake, their patient might die. It's a last resort.
In any event, the cost is very worth it, so we don't need the machines to be cheap, but they must be simple enough to be made fast, from off the shelf or easily mass-manufactured in factories which can be brought up to full production without putting their workers at major risk. Not easy.
Smart CPAP hardware with new firmware = Ventilator?
One option is being explored by several people. It is not yet verified to be practical, but if it is, it has many attractive elements to it. Around 20 million people in the USA have a condition known as obstructive sleep apnea, which means their airway can close up when they sleep, temporarily shutting off air and waking them up. Millions of them treat this with what is called a CPAP machine -- which blows air into their nose via a mask at higher pressure, and keeps the airway inflated. Over the years, these machines have become much more sophisticated, and several million of them are made each year.
A CPAP is not a ventilator, but can the hardware in modern CPAPs help create a ventilator?
The current machines can blow air with a computer controlled blower that can change the level of pressure instantly. They have sensors to detect the air pressure, sound and air flow. The older machines did not do this, they just stuck one one basic pressure, but the newer ones tend to have this ability.
While CPAP machines are not ventilators, and don't have software to deliver assist control or pressure control ventilation, they may contain much of the hardware needed for certain types of ventilation. What they don't have is the software.
Normal CPAP machines deliver a max pressure of 20cm of water. (That's not much, about 2% of atmospheric pressure.) Many ventilation patients use much less than that, but serious ARDS patients need that and more. Ventilators usually are rated to deliver over 40cm, though they don't normally go to that level, as it's dangerous.
Researchers have discovered, though, that the blowers used in some CPAP models are capable of 45cm and up to 400 l/min of airflow, much more than is needed for CPAP, and enough for ventilating many ARDS patients. Less established is whether these blowers and their electronics might fail if used 24 hours a day at these levels. My intuition is that most medical devices are built with wide tolerances and this will not be the case, but it must be confirmed. If 24 hour operation is not practical, there is a solution -- patients can have two or more machines, and have their machine switched every 8-10 hours, which is the normal duty cycle of CPAP machines. Because there are so many millions of CPAP machines out there, this remains an option.
Some patients can be helped with the CPAP or BiPAP therapy these machines deliver with their current software, and that's good. However, under discussion is not using CPAP/BiPAP to treat patients, but rather converting such machines, by replacing their internal software, to apply ventilation.
In fact, if two machines are available, they can both be hooked up to the patient's air tube, through a valve that allows either one (or both) to blow air but which prevents blowback into the unit. This allows automatic handoff between two machines, and also means that if failure is detected in one machine, it can be turned off and the other activated to take up the slack, also making an alert to replace the bad machine in reasonable time. This could result in an extremely high level of reliability.
In particular Covid ARDS patients are being ventilated at a fairly high pressure. In many cases, the minimum pressure (PEEP) is set at 16cm, which is high for a CPAP. The upper pressure limit varies -- it is not set, but is whatever it takes, up to a limit, to assure sufficient air flow through the lungs.
To act as ventilators, the machines would be converted by loading new software in their controllers. Fortunately, most of them can be field upgraded with new firmware. Many of the leading CPAP vendors, such as Medtronic/Puritan Bennett and Phillips Respironics, also make ventilators and are already familiar with the algorithms and software needed.
Some of these machines feature return tubes which can be used to measure pressure at the interface instead of in the machine. This is superior, but was largely eliminated from newer machines as no longer necessary. It is not known if this is needed.
Monitoring and control
Most of these machines also have a USB port, which can be used to set up the machine and to upgrade its firmware. New ventilator firmware could also use this port to communicate with a control and monitoring computer, which could either be based on a standard mobile phone or an old laptop running a free operating system such as Linux from a USB stick. This monitoring computer would not be life-critical. It would be used to:
- Provide a GUI to set up the ventilator and all its parameters
- Receive data from the ventilator to display what's going on, including detecting any problems. Display a graph of pressure, volume and flow over time.
- Sending this data and any alerts to central nursing stations (more than one in case of failure) and anybody else that needs to know. In addition, they would send, and relay from the ventilator a "heartbeat" regular signal so that the failure of either device would be noticed at the nursing stations, causing somebody to be dispatched.
While the monitors would communicate status over Ethernet or WiFi, they probably would not receive commands back that way, or if so, only over a non-internet verified channel, to avoid risks of computer intrusion changing parameters of the machines. Of course that means problems require dispatching of a qualified staffer which has its own costs.
(Some modern CPAPs have a cellular radio in them, or wifi. This may also be usable.)
I have prepared a set of notes on functions of the monitoring system.
ARDS patients tend to require fairly high pressures. They are often run with a minimum (PEEP) pressure of 14 to 16cm. This holds the alveoli in the lungs inflated open. ARDS patients prefer low tidal volumes which means a very high concentration of oxygen -- as much as 95% to start -- is desired. Most ventilation is done in Assist Control mode where you set a flow volume (ie. ml per breath, with a minimum breath rate) and the machine tries to deliver enough pressure to deliver that volume. If it can't, it sounds an alarm. It also alerts if the volume is not delivered and high plateau pressures suggest the lung is not accepting the air well.
ARDS patients are often intubated (tube down the throat into the trachea) and heavily sedated so they will tolerate that. In may cases so sedated they don't initiate breathing on their own all the time. Fluids can also build up which must be detected and suctioned out.
What a ventilator does
At a very basic level, a typical AC mode ventilator blows pressurized air (which is usually 50% or more oxygen in an ARDS patient) into the lungs to inflate them, then reduces pressure to let them deflate out an exhaust tube or port. It will be set with a base pressure (high for ARDS patients,) a tidal volume (how much air to pump in per breath, for example 500ml,) an oxygen concentration, a minimum breathing rate and various alert thresholds.
It starts hoping the patient begins to draw breath (which drops the pressure in the system, detected by a pressure sensor.) It then increases the pressure over the base to deliver the volume of air. If the volume isn't going, it increases the pressure up to a limit. Then, it reduces pressure down to the base level and lets the air come out. If the patient doesn't draw breath again within the minimum breathing rate, it will increase pressure on its own to cause a breath anyway. It uses various algorithms to look at the pressure and flow curves to figure out what's going on, or if anything is going wrong.
This mode is the most common. There are other modes which aim for a certain pressure rather than a certain volume of air (and have alarms if the volume is too low) and several others.
This more detailed engineer's summary of ventilation gives you lots more detail.
It is also necessary to provide most patients with supplemental oxygen, often quite a lot of it. It is unknown if it would be safe to feed high concentration oxygen through the blower. Normally with CPAP lower levels of supplemental oxygen are added at the mask/interface. This problem needs resolving. CPAP hardware itself does not have anything to control mixing of oxygen and regular air.
Disturbingly, some patients are needing almost pure oxygen. Pure O2 is toxic long term and it must eventually drop to 50% or less, but this is very high, and if fed through the machine, we must be sure there is no fire risk, even if things overheat or humidifiers dry out.
Many CPAP machines do not have an air inlet port, rather they take in air through a filter and it is not easy to attach anything to the inlet. Some do have an inlet port. They all have a standard outlet port, however.
Full ventilators have internal air-oxygen blending and even oxygen concentrators. External air:oxygen blenders exist, but may be difficult to get in the quantities needed.
Fortunately, you can add O2 at the tube going into the patient. This is done with CPAP, and research shows that even at 20cm of CPAP, you can accomplish 50% concentration of Oxygen, so a similar level should be possible with ventilation in the 15-25cm range, one hopes. This means the Covid patients may not be able to start this way but can be weaned down to it. This will involve venting extra oxygen to the room, so the room should be sufficiently ventilated so as to not increase its own O2 levels too much.
Patient interface would not be a typical CPAP mask for most patients. In fact, for ARDS patients an intubation into the trachea will be necessary with sedation. That tube will need valves to control flow and to assure expired air is filtered for virus particles.
In operating rooms, ventilators typically run on a closed circuit using chemicals to scrub the CO2 and return the flow back to the patient.
Most of these CPAP machines, when operating in their normal pressures, are low power. They run at 12 to 24 volts and only draw an average of about 12 watts. Their humidifiers (which is important for ventilation) draw much more power but sometimes from a separate circuit. The basic machine, however, can run off a typical marine/RV battery for around 60 hours, less at 25cm. And for 30 hours from a typical car battery. They can be hooked up to such batteries and the battery can also be hooked up to a low-current slow charger so the machine runs off external power but can run for multiple days -- and most of a day with humidification -- if the power goes out.
Alternately, these machines can be plugged into standard "UPS" units sold for computers. They might only run for an hour on such a unit but it should be enough to find other solutions if preparations are made, such as generators.
Generally, we want to keep this simple, and the ventilator must be. However, the control computer which is pulling data from the ventilator and displaying and relaying it could have some more innovation. Today, monitoring a patient and adjusting their ventilation is still considered partly an art among doctors, being able to read the pressure and flow graphs and understand what's going on, predict risks and adjust settings. That's actually the sort of thing neural network AIs can get good at if given data from the actions of skilled doctors and respiratory therapists. And that data could be gathered from patients being treated through this new interface.
This could be of value because if there are hundreds of thousands ventilated, there are not enough doctors to monitor and fine tune their treatment. While we would not quite be ready for the AI to do that, it could make recommendations, and signal alerts about potential problems coming down the line, and doctors could make decisions. In particular, there are a number of interesting stories about how such networks have learned to spot problems even before the skilled doctors do -- you give them the data from lots of patients and what problems they had, and they can uncover clues not seen before.
Loaner machines must be fully sterilized after donation and before return, and between any two patients. Hopefully this can be done in bulk, buy putting lots of machines in a room running at low speed, and flooding the room with ozone or other killer of pathogens.
I believe that people would stup up to loan machines and donate old computers. A tax deduction could also facilitate this.
While questions remain unasked, the value of this is strong. These machines already exist and do not need to be manufactured. In addition to what sits in inventory, millions of people have new machines and also have old machines sitting around, in some cases several of them. They can happily use those machines and loan out their newer model. Large numbers of patients are prescribed CPAP and get one bought by insurance, but decide they don't like it and turn it off. It would not be surprising if the number of such available machines ready for donation could be very large. The hardware, while not designed for ventilation, is medical grade and it exists. The control stations can be the hundreds of millions of old laptop computers or phones also sitting on shelves, a large fraction of which can become a dedicated station by booting from a flash drive. With batteries, these devices also can handle power failures.
Still needed are the hoses, interfaces and filters, plus possible additional solutions for oxygen and humidification. But a large part of the problem may already be solved.
The current vendors, if they decide they can do this, will be afraid. After all, the hard truth is these are not ventilators. Some will fail. Patients will die. While they are probably patients who would have died anyway, this is still a risk companies are not willing to take. They probably won't take it unless they are granted a waiver from such liability. Even so, that's why the monitoring system is important, so that it is expected these machines will fail and it will be detected immediately and fixed immediately. With enough machines, a backup machine can be sitting nearby.
The other question is how they are allocated. In one scheme, patients can be triaged to use higher end FDA approved ventilators. The CPAP based devices would only be used on patients who would otherwise be told, "we don't have a ventilator for you." In Italy, sadly, a number of people have died when this was the case. The cheaper devices can generally only improve things.
The FDA has loosened regulations even declaring that modified BiPAP and CPAP can be used to maintain airways, but this only helps some patients.
On the other hand, if we decided that the CPAP based machines can do a job on a body of patients who have lighter needs -- they may need less pressure or less oxygen, for example, a rational approach might be to assign all such patients the lesser machine and reserve the more expensive official machines for those who must have them. This can be a good result but it might mean that a patient who would have passed the triage for other reasons now might face the failure of a lower end machine. It's a terrible choice, but still saves the most patients.
ARDS-ICU beds are still needed for these patients. It is unlikely vetilation could be done safely at home. It could be adapted to temporary ARDS ICUs currently being constructed in unused buildings like convention centers.
Upate: The UK has released a specification for simpler ventilators for this emergency. Most of these requirements can probably be met, though oxygen safety is unknown, and PEEP over 15cm will need confirmation.
To be researched
The Cuirass ventilator, a descendant of the iron lung, is a chamber that goes around the chest. You suck air out of it, creating a pressure differential that sucks air into the lung. This is bulky and rarely used, but has the tremendous advantage of not needing intubation or sedation. Because of the high minimum pressure ARDS patients need, it is possible it might not be enough on its own, but could be combined with an adapted CPAP which would provide the base pressure while the Cuirass system uses negative pressure to increase the differential.
- Can 95% oxygen, or even 50%, be safely inserted into the air flow?
- Can the output vent be safely filtered to avoid spreading viruses?
- Can CPAP blowers and electronics operate at 20-30cm pressure on a 24 hour basis for days and weeks at a time with very low failure?
- Can CPAP vendors be convinced to release new firmware, and when?
- Can independent parties write new firmware and reflash these units?
- Can enough air:oxygen blenders and patient interfaces and more be supplied?
- Do we need additional sensors (extra pressure or flow sensors, O2 sensors) which can be hooked into the laptop via USB?
- Can we pull off the automatic switch from one machine to another, including switching oxygen? Switching machines is perilous when done by hand.
LawProf John Banzhaf
Mon, 2020-03-23 07:22
CPAP Use To Supplement Ventilators
FDA Finally Authorizes CPAPs To Meet Ventilator Shortage
Responding to growing pressure
the FDA has finally begun to recommend the use of common CPAPs to help COVID patients desperately
needing help breathing
as suggested by LawProf John Banzhaf
WATCH TV INTERVIEW
How CPAP Machines Can Save Lives
When We Run Out of Ventilators
HOW TO DONATE OR USE
Public Interest Law Professor John Banzhaf
George Washington University Law School
Mon, 2020-03-23 11:19
Strangely, a lot of people who read this make this mistake. The proposal is not in any way about using CPAP or BiPAP therapy to help patients, which indeed has already been approved. It is about replacing the software inside CPAP hardware to make it do ventilation.
Tue, 2020-03-24 06:10
CPAP used as ventilators
With regard to this issue
1. Ordinary CPAP APAP or BiLevel PAP machines as manufactured will not work
2. CPAP type machines with a backup rate for ASV and machines made for non-invasive ventilation could be used
3. The idea would be to substitute "CPAP" for traditional ventilators in those patients with less intense needs and free up traditional ventilators for the worse cases
4. With regard to safety for patients on "CPAP" monitoring of O2 saturation and/or end tidal CO2 could be helpful
Tue, 2020-03-24 08:49
That's the whole point
I've tried to say it as explicitly as possible, but this is not discussing using unmodified CPAP machines or CPAP therapy.
Wed, 2020-03-25 08:34
I've reached very similar conclusions
In fact it's interesting how close our ideas and analysis are:
I've created a mailing list to further discuss the idea; it'd be fantastic if you could join!
There are some key questions that our initial analyses both missed;
* ResMed say bi-level machines can be used, but normal CPAP not. On the other hand some doctors are saying CPAP is good enough and bi-level may even be harmful. So which is it?
* Hardware differences between bi-level and Auto-CPAP machines, can they be overcome? Primary differences beyond firmware seem to be bi-level may have an intake throttle auto-cpap doesn't but that needs to be confirmed, and also, does it matter? Can the motors react fast enough (halve/double speed within 100msec) or are the electronics not specced for that kind of acceleration?
Wed, 2020-03-25 13:55
Older bi-level machines had special hardware to assist in delivering two pressures. My impression -- not fully confirmed -- is that modern bi-levels (and other machines that provide pressure relief on exhalation in "flex" mode) are just the same machine with different software, now that they use digital motor controllers on the blowers. It seems hard to see why they would act differently.
In decades of the past there was a real hardware difference between a plain CPAP -- that had no sensors and controlled the motor speed in very simple ways -- and auto-titrating CPAP (which added sensors to detect flow anomalies) -- and bipap. I am not sure this is true any more, but need to see inside the machines.
While not all machines can do this job, I suspect many can, but only vendors can confirm that. I still need to understand how much oxygen can be delivered and safely. My instinct is that putting 95% oxygen through a device not designed for it needs a lot of confirmation.
Wed, 2020-03-25 20:57
Adapt, improvise, overcome
I use a Resmed S9 CPAP every night at 16cm of water thru a nasal mask. My wife, who does not have obstructive sleep apnea like I do, has some ongoing respiratory issues. We are both concerned about getting COVID-19 when treatment resources may be severely limited and may be triaged to a lesser level of care. My plan at this point my is to use my CPAP (and the identical spare I picked up a year or two ago) in conjunction with an oxygen concentrator. I have a mask that accepts a cannula and I recently fitted my wife with a similar mask. My hope is that we have sufficient resources for self-care at home, if either of us doesn’t make the triage cut.
Thu, 2020-03-26 01:53
Yes, many patients are being treated with just cpap or bipap and supplemental oxygen. However, too many patients need full ventilation, and that's where the shortage of machines is. If you are in the group unlucky enough to need supplemental oxygen, but not unlucky enough to need ventilation, your setup, from what I understand, could help you, but you would want a doctor to confirm that and tell you what to look out for in case you need to go to the ICU. You probably would only use your gear if the hospital is full.
Wed, 2020-03-25 21:01
I'm a pulmonary physician. We
I'm a pulmonary physician. We regularly use BiPAP (similar to CPAP) to "bridge" patients into mechanical ventilation (that is, we see if we can get by without intubation, etc) and to "bridge" patients after extubation and liberation from a ventilator (to help them get back to breathing on their own). We use BiPAP a lot in the ICU for this, so it's not a new idea. I can get a BiPAP machine in the ICU in just a few minutes; we have plenty of them.
A major problem using CPAP and BiPAP machines for patients with COVID infection is that these are "open circuit" machines -- when a patient exhales, the exhaled air goes out the mask into the room. Because there is some pressure the exhaled air can travel to nearby surfaces. For a COVID+ patient, that is very much a bad idea and will serve to spread the virus.
A ventilator, in contrast, is a "closed circuit" machine -- the exhaled air goes through a separate exhaust port and filter.
Converting a BiPAP machine to a closed circuit loop is no trivial matter; that is what is limiting their use for COVID+ patients. Initial recommendations from the CDC and various societies, and from Italy, was not to use them.
In our COVID+ ward at the university hospital (> 60 patients now, 18 in critical care) we're beginning to reassess this. In the ward we assume everything is positive, and all personnel are wearing PPE. So the issue may not be as big a deal.
Another point: while the 'blower' in both a BiPAP machine and a ventilator can deliver high pressures, in ARDS that's a decidedly bad idea. My ICU mentor from 35 years ago (Lawrence D. H. Wood, one of the pioneers of this) led studies, and additional multi-center studies confirmed, that high-pressure ventilation worsens mortality in ARDS. This happens (we think) because the high pressures and volumes over-stretches the lungs, setting up a fibrotic reaction that destroys lung tissue (for physicians, this is known as "proliferative stage" or "fibrotic stage" ARDS, and is very, very often fatal). Later studies led by Jesse Hall (another mentor of mine) demonstrated that low-volume ventilation delivered the best results by avoiding this problem. This is now the standard of care in critical care medicine -- we ventilate just enough to oxygenate the patient and no more.
So just because the blower can go to '11' doesn't mean you should crank it up.
Thu, 2020-03-26 01:51
Thanks for advice
But I have to say I don't understand why you wrote many of the points there as they are all addressed in some cases in great detail in the article. The article, as it says 3 times now because for reasons I can't explain people keep saying it, is not about using BiPAP or CPAP on these patients. It is not about using typical CPAP interfaces which exhaust the air. It explicitly says this pretty clearly I thought, so I am baffled you bring it up. So please let me know what I can do to make it more clear in the article that none of these things are proposed in the article, and the opposite is proposed. People, not just you, are somehow missing that.
In the proposed solutions, the bipap machines would be changed to output the same pressure profiles and use the same algorithms as ventilators. They would be ventilators. They would no longer be CPAPs. They would use ventilator interfaces and exhaust filters.
We do need the help of pulmonary physicians so I need to find a way to make this clear. This question of the pressure is an important one. I've seen articles from other doctors, and talked to different doctors who do a lot of ventilation and they have told me what I report above -- that ARDS patients need higher PEEP and lower volume and higher FiO2. If that is not true for Covid patients that is important to know. It also makes it easier for the hardware inside the CPAP machine to be changed to work as a ventilator as the pressures are more within the hardware's normal working range.
One thing I want to learn more about is gas mixing. I am worried we can't mix in the O2 before the machine, but if we mix it after the machine, can that even work and how much FiO2 can it deliver without risk of backflow into the machine we we fear has risks -- we don't know it does and we don't know it doesn't.
Thu, 2020-03-26 21:56
Virus aerosolization issue not addressed
I don’t see how your article addresses Steve White’s points about virus aerosolization, except for stating that filtering exhaust ports is required and asking how it can be done. It appears that it can’t be done with just CPAP hardware (Steve White’s comment provides evidence of why this is the case), so where would the hardware for creating an enclosed system come from? It looks like an enclosed system is required to control pressure without aerosolizing the virus. Just adding a physical filter like N95 respirator material to the exhaust port would likely “block” the exhaust port and create positive pressure. As Steve White mentioned, it would not be trivial to convert a CPAP machine to a ventilator due to very different hardware and mechanics, namely non-enclosed versus enclosed system.
Fri, 2020-03-27 01:06
Virus aerosolization is not a property of CPAP machines per se, it is a result of the exhaust ports on the mask. Intubation would not involve a CPAP mask, obviously.
Patients on operating tables use closed systems, this is not so common in ICUs from what I understand. As such, something needs to filter the output. There are many solutions though some wonder if they are enough with air under sufficient pressure. But all this has nothing to do with CPAP or CPAP machines. Some people getting cpap/bipap therapy will use nasal or full face non-invasive masks. The issue here is the same for any fancier non-invasive approach.
My frustration is that lots of people read about this and they say, "silly rabbit, cpap spreads the viruses out." They don't seem to get we are not talking about CPAP, CPAP masks.
If we can get the CO2 scrubbers in the line then you could do a closed system which has many advantages, other than the cost of the chemicals and keeping them plentiful.
Sun, 2020-03-29 08:44
Ventilator hardware required for modding
If the problem is that there are not enough ventilators, where a ventilator includes a ventilator mask and hardware for a closed system and CO2 scrubbing, how does reprogramming CPAP machines without ventilator parts solve this problem? Where would all these extra ventilator parts come from, given that there is a shortage? If you need to manufacture these parts for modding, why not just manufacture complete, existing ventilator designs that have been tested and certified?
Sun, 2020-03-29 22:29
The parts, like hoses, valves, intubation tubes etc. tend to be plastic parts that are easy to mass manufacture, and are made in large quantities already because they are often disposed of per patient. I am more confident that spooling up manufacturing for tubes and valves and filters to quantity one-million is doable in a way that making a million complex ventilators is difficult.
Note that closed circuit ventilation is generally for the operating room. However, OR doctors tell me they don't see why it could not be used at scale in the ARDS ICU.
Thu, 2020-03-26 11:36
Look up a Resmed Lumis TX
Resmed makes a souped-up version of their previous generation S9 for hospital use, it is called a Lumis TX and it is as far as I can see exactly the same as a regular S9 with the addition of an alarm module and different software. This model supports the following therapy modes: CPAP, AutoSet/APAP, VAuto, ASV, ASVAuto, S, ST, T, iVAPS, and PAC. They call it an all-mode non-invasive ventilator.
It will support pressures up to 30cmO2. These machines basically max out what is possible with standard CPAP hardware with only software changes. I do not know if they add any sensors to be able to provide specific tidal volumes but I suspectt that the hardware is exactly the same.
Thu, 2020-03-26 12:42
I mean if the old S9 could do that, I presume the later models could too. They have an FAQ on their site but it seems to shy away from suggesting machines can be repurposed. But if the hardware in the S9 and do iVAPS, it makes it seem more likely.
Mon, 2020-03-30 06:21
So if you have a CPAP @ home it does not matter about the exhaust air with Covis-19 as whoever is in the same house will have it already. What we need is the understanding of how to attach Oxygen generation to the CPAP, I have a Soclean on my Dreamstation so have a tube that attaches to the humidifier, how can I attach and control the Oxygen needed to here?????
Mon, 2020-03-30 21:58
Not about CPAP
This article is not about CPAP therapy. If you are somebody that CPAP can help, you don't need new firmware for the hardware. Almost all masks are designed to work with oxygen concentrator, but home treatment is a last resort. The machine is not involved.
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