pulse oximeter for health monitoring? - Page 1
Forum section: electronics / projects

author: JBeale
author_rank: Frequent Contributor
timestamp: March 29, 2020, 05:39:40 am
content: I was curious about these devices, given the current events.I got a cheap one yesterday: CONTEC Pulse Oximeter Model CMS50M. (from another vendor, but Amazon has them)https://www.amazon.com/CONTEC-CMS50M-Oximeter-Waveform-Carrying/dp/B07D8R4G5HThis uses 2x AAA batteries, and clips over the end of one finger. It apparently uses two LEDs: 660 and 880 nm both shining through your finger, and the ratio of total absorbance at those two wavelengths goes into a lookup table to compute SpO2 or "peripheral capillary oxygen saturation, an estimate of the amount of oxygen in the blood." It displays pulse rate (BPM) and SpO2 on a LED display, along with a real-time bargraph showing each detected pulse. This one is live-readout-only, some fancy ones have bluetooth so you can log the data to an app.Normally on my finger it indicates 99% SpO2. Just now I tried holding my breath for 40 seconds, which is about as long as I wanted to. At T=40s when I started breathing again, the meter had only gone down to 97%. Interestingly, although I then continued breathing normally the meter continued slowly down for awhile, reaching 91% at T=59s before quickly rising back up again to 99% at T=70 s. There must be some delay in O2 transfer and blood circulation from lung to fingertip, but I don't know how much of the total readout delay is some real physiological thing, vs. some internal (possibly asymmetric) lowpass filter in the meter.Of possible interest, yesterday I felt pretty fatigued with slight but noticeable shortness of breath feeling which is very unusual for me. I had no fever, but occasional cough and headache. I did this experiment yesterday with similar results on the SpO2 numbers, starting out 98-99 slowing going down to 93% then bouncing back up, but the difference was that yesterday I could only hold my breath for about 10 seconds. However I am feeling more energetic today and maybe I just have more practice in breath-holding now. FWIW

author: penfold
author_rank: Frequent Contributor
timestamp: March 29, 2020, 10:00:57 am
content: The body is full of feedback loops, so under a step change, there will be a lot going on which ensures the most critical functions are being looked after first, your finger probably being the first to get overlooked and the last to get restored. As a steady state measurement after a period of rest etc, its probably representative of the more critical blood gas saturations within the body, but dynamically there is a lot going on that will influence that measured at the finger.I couldn't cite any specific sources right now but.. the same kinds of hormone responses that trigger "white-coat hypertension" could have an effect on the pulse oximeter readings through blood vessel contraction/dilation, it is unfortunately immensely difficult to get any valid readings of pretty much anything in the body since even that "being curious" feeling will trigger some very slight physiological changes towards nervousness/anxiety and even being slightly excited about having a new gadget to play with will do similar..

author: taydin
author_rank: Frequent Contributor
timestamp: March 29, 2020, 10:21:37 am
content: My father has advanced stage chronic heart failure, and even with him the oximeter indicates above 97% saturation. Before he received his ICD implant, right before he was going to undergo the operation, the oximeter was swinging wildly between 80% and 100%.So the oximeter will only show low oxygen concentration when there is a life threatening drop, which would have already so many other symptoms that you would be compelled to go to the ER without even considering the use of an oxymeter.

author: hans
author_rank: Super Contributor
timestamp: March 29, 2020, 10:35:02 am
content: My Samsung S7 also has a SpO2 sensor.I tried it first when laying flat on the couch. I think it read something like 95%. I sat up, and it jumped back up to 97%.Later that day I went out for a walk, and it fluctuated between 97% and 100%.I'm not sure how reliable these measurements are. Under stable and repeatable conditions probably pretty reliable, but under changing circumstances there is probably quite some tolerance.I had similar symptoms as you mentioned. I put them down to stress & anxiety usually, even at strange times like these. I would only start to worry if the readings would drop further, and I actually feel sick. However I'm now medical doctor, so take my findings for even less than 2 cents.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 29, 2020, 11:38:29 am
content: The phone has to measure in refection and this can be less accurate than the transmission configuration used in the classical pulse-oxymeters.Usually the saturation is quite high and one would notice a drop quite a lot. So the saturation is more like an alert signal in intensive care, maybe telling the doctors when they need a respirator or extra oxygen.For private use the pulse reading may be more useful, especially if used under well defined conditions, e.g. in the morning. It may help the doctors to know the individuals pulse rate at rest when healthy. However usually no need for an extra instrument for this. One can usually do it the old way. For some heart problems the changes in the PBMs may give some help to an expert.

author: BravoV
author_rank: Super Contributor
timestamp: March 29, 2020, 11:42:17 am
content: Bought two for comparison as they're quite cheap, assuming its very unlikely that both have the same "in-accuracies" as both are different brands.Measured after an exercise.Also bought few MAX30100 boards for DIY.Also simple DIY pulse oximeter done by bd139 ->HERE

author: JBeale
author_rank: Frequent Contributor
timestamp: March 29, 2020, 02:29:44 pm
content: Thanks for those notes and observations! Yes, I agree any number of variables are involved and the point about feedback loops is well taken.At this point I'm confident of only one thing: "shortness of breath feeling" and "how long you're willing to hold your breath" are entirely subjective things. By contrast, the SpO2 reading during and after holding breath for a fixed length of time, may be subject to many variables, but at least the readings themselves are not subjective. The SpO2 reading in steady state seems to be always near 99% unless you're in very poor health, but holding your breath for a fixed time gives something measurable on this simple meter.Today (Sunday March 29, which is 2 days after getting the meter on Friday March 27) I'm not feeling as tired, and I notice that while holding my breath for 10 seconds or even 20 seconds, the meter never drops below 97%. When I was feeling tired and short of breath on Friday, the meter did drop down to 93% after only 10 seconds of breath holding. I tried the 10-second test three times on Friday, and got 93% +/- 1 each time. Today, I can get to 93% but I need to stop breathing for 40 seconds. There may be so many factors affecting the number that by itself it means little, but I think at least the minimum-Sp02-after-fixed-time measurement is something quantitative. For me it seems both repeatable on a given day, and also correlated to the subjective feeling of having energy or not.

author: calzap
author_rank: Frequent Contributor
timestamp: March 29, 2020, 02:41:28 pm
content: One useful thing you should try with a pulse oximeter is check whether you have hypoxic sleep apnea. It's a disorder that is initially hidden from many who have it. Assuming the PO can record or be connected to a computer, record readings at least every 5 minutes through the night. If it dips more than 5%, talk to your doctor.Mike in California

author: golden_labels
author_rank: Super Contributor
timestamp: March 29, 2020, 04:24:35 pm
content: JBeale:Two things to note.When you hold your breath, what you feel and what is forcing you to inhale air is not low oxygen level. Your body does not crave O₂. This reflex is caused by increasing carbon dioxide concentration. And, how counterintuitive it seem, if you are deprived of oxygen your body will produce less CO₂ and the phenomenon is weaker. This effect is used in suicide by inhaling inert gasses — but do not try it at home, as it may lead to brain damage (suicides are generally dangerous). Therefore, if you hold your breath, you still have up to many minutes worth of oxygen reserves and you should not expect pulse oximeter to show sudden dip in oxidization levels. Actually static apnea records with pre-inhaled pure oxygen are well over 20 minutes, and with the modern CPR guidelines artificial ventilation is optional: what they have in their lungs and what is accidently being circulated during heart massage is seen as more than enough to keep them alive.Pulse oximeters work on blood in the tissue, not in the artery. All delays in feedback loops aside, it simply takes time for fresh blood to replace old one and the readings will be both retarded and averaged over time. By its nature the situation is similar to what you observe in continuous glucose monitors.

author: JBeale
author_rank: Frequent Contributor
timestamp: March 29, 2020, 06:28:54 pm
content: I asked test subject #2 (my wife) to try it. After holding her breath for 30 seconds, the meter was still at 99% and it continued to stay there. So it looks like my observations do not generalize beyond test subject #1 (me). Oh well!At my last checkup my blood pressure was lower than normal. Maybe indicated SpO2 change with my brief apnea test is some secondary effect related to that.It's almost as if biological systems are more complicated than the electronic systems I'm more used to working with. :-)

author: Buriedcode
author_rank: Super Contributor
timestamp: March 29, 2020, 08:30:43 pm
content: Be careful. With these things the accuracy can be questionable (https://www.ncbi.nlm.nih.gov/pubmed/27089002), but it is mostly the interpretation of the measurements that matters, and thats why doctors with experience will be more qualified than a laymen, or someone who has googled for 10 minutes. Single data points of things like pulse, O2 sat, and blood pressure can't really tell you much. It is trends in these things that matter more - sustained high blood pressure, or O2 sat <95% regularly.We live in a golden age of health monitoring, with pretty cheap and reasonably accurate sensors widely available. Whilst its a boon for companies to have access to this data, this has also increased health anxiety as people forget there can be a pretty wide variation in measurements.What was the question?

author: JBeale
author_rank: Frequent Contributor
timestamp: March 29, 2020, 08:52:44 pm
content: The question I had in mind, is whether periodic measurements from a cheap pulse oximeter can be used to detect reduced pulmonary function, for example, due to viral inflammation, before things get critical. Eg. could you use it in the same way people use a fever thermometer. to check for indications of possible disease. Esp. if you suspect the condition you're trying to detect does not always cause a fever.The answer appears to be: the sensor isn't very sensitive to small variations, so it would not be an early-warning system, more like a too-late warning system.

author: Buriedcode
author_rank: Super Contributor
timestamp: March 30, 2020, 01:58:04 am
content: Quote from: JBeale on March 29, 2020, 08:52:44 pmAnd even if it was sensitive to small variations - heart rate is pretty easy to measure accurately - how would you know it indicates any kind of viral infection? My point was, measuring things is easy, but knowing what those measurementsmeanis the hard part. Also, say if your heart rate increased when you were unwell, does that happen to everyone? and by the same amount?This is the problem with lots of health monitoring, it is assumed that because it is now much easier to measure lots of things, we can translate that into very meaningful and helpful action to take. Sure, if you're heart rate is 140 all the time, thats probably bad, but trends and subtle variations could mean any number of things.It would be nice if there was a way to detect infection using heart rate, an ECG or something, but I am unaware of any. With all that said, there is nothing wrong with taking regular measurements and plotting the results for your own interests. But the person who should be interpreting those results should be a (your) physician. If you're looking at O2 sats to measure lung function, by the time you get readings low enough to be worried about - you'll probably already feel quite short of breath, if its consistent then that might show a problem.

author: thinkfat
author_rank: Unknown
timestamp: March 30, 2020, 08:24:56 am
content: Quote from: JBeale on March 29, 2020, 08:52:44 pmOur son has had pneumonia two times in the last three years and we bought a pulse oximeter for being able to more frequently monitor his saturation levels. After the first time, which got pretty severe because the condition was not detected properly (asymptomatic case, no or low fever, just cough and snotty nose), we caught it early the second time because we knew the pattern already and checked saturation levels regularly. The saturation went below 90% and we took him to the hospital. The values measured there confirmed what our meter displayed.So, it can be useful. I bought another meter for my parents for them to check on their levels regularly.

author: mzzj
author_rank: Super Contributor
timestamp: March 30, 2020, 09:24:46 am
content: I had mild lower respiratory tract infection(covid??) 2 weeks ago, pulse oximeter was showing about 94-95% readings on the worst days when chest was feeling heavy and I felt exhausted even by just standing. Now back to 98%Same for my friend who had probably same infection going on at the same time. Adults can probably "gauge" their feeling better but it might be useful with kids that are harder to interpret.Doctor was interested if I can hold my breath for 10 seconds, apparently its some sort of indication about how bad shape you are in.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 30, 2020, 04:03:33 pm
content: Quote from: JBeale on March 29, 2020, 08:52:44 pmAs you figured, those cheap sensors are not that accurate to begin with.But even with the kind of sensors used for medical monitoring, the moment SpO2 falls below a threshold which is a hazard, the time left to act is very short.During surgeries or for patients in ICU, when the SpO2 is at an alert level, there's only a VERY short time to act before there could be irreversible damages...Conversely, monitoring the SpO2 just to figure out if someone isn't breathing right, or is in short apnea (as you tested), but not in any critical condition, just doesn't really work in the general case. Just as you saw with your limited experimenting, it varies a lot depending on each individual and exact condition.A related idea would be to use pulse oximetry to monitor sleep apnea, but it doesn't really work. Monitoring inhaled air pressure is still much more effective for that.

author: alanambrose
author_rank: Frequent Contributor
timestamp: April 01, 2020, 11:05:57 am
content: Well I thought too that the £20/$25 pulse oximeters must be cheap-ass inaccurate consumer stuff.But actually I compared my non-name consumer one against a Nonin professional device:https://www.nonin.com/products/8500/... and they essentially came up with the same numbers. Sometimes you can be pleasantly surprised...So, I'm happy to use it to help monitor my asthma and potentially the breathing impacts from the virus. I'm using >94% normal; <90% be concerned - and I'm expecting to be feeling quite short of breath in the latter case.Alan

author: taydin
author_rank: Frequent Contributor
timestamp: April 01, 2020, 01:03:28 pm
content: I think just looking at the oxygen concentration would be incomplete. The pulse is also very important. It could be that the lungs starting to fail, but the heart is compensating by pumping more blood and further stressing the lungs. If this scenario, the oxygen concentration would be fine, but at what cost? At the cost of stressing the heart and the lungs.

author: JBeale
author_rank: Frequent Contributor
timestamp: April 21, 2020, 06:54:42 pm
content: It is my understanding the weight of opinion in this thread has been that pulse oximeter monitors are not useful for early detection of COVID-19.There is anarticlein yesterday's NY Times by Dr. Richard Levitan, who has been practicing emergency medicine for 30 years, and teaching airway procedure for 20 years.Based on his experience after 10 days in Bellevue (NYC) treating COVID-19 patients, he observes this disease behaves in unusual, if not unprecedented ways.Notably, he found patients can have low SpO2 readings without realizing it; something not normally true. Accordingly, he has a different opinion about pulse oximeters.Quote from:https://www.nytimes.com/2020/04/20/opinion/coronavirus-testing-pneumonia.html

author: trophosphere
author_rank: Frequent Contributor
timestamp: April 21, 2020, 07:42:04 pm
content: Quote from: JBeale on April 21, 2020, 06:54:42 pm.eOther circumstances can result in people having asymptomatic low oxygen saturation such as having history of Atelectasis, COPD not in exacerbation, Chronic Heart Failure, Congenital/Acquired Cardiac defects resulting in shunting, Hemoglobinopathies, Obesity Hypoventilation, and even just after Smoking. I admit and see patients in the hospital and you would be amazed at how many patients have an episode of asymptomatic hypoxia during their stay.Suffice it to say, asymptomatic hypoxia is not specific for Covid-19. Rather, it would be just about as useful as finding someone with an elevated temperature.I think the general thought is that a finding of asymptomatic low oxygen saturation is not a specific finding just for Covid-19 - it's not specific.

author: JBeale
author_rank: Frequent Contributor
timestamp: April 21, 2020, 08:00:58 pm
content: Quote from: trophosphere on April 21, 2020, 07:42:04 pmMy initial thought was along that line, that it could be a clue, in the same way fever, cough, and shortness of breath are clues (and yet non-specific).I did not mean to suggest it was a substitute for a PCR test.However if a pulse oximeter is accurate and a person does have a sustained abnormal low oxygen level, does that not argue for prompt investigation, virus or not?Some comments on the NYT article complain that early detection does no good, if the hospital's advice is for all non-severe cases to say home anyway, and there is no officially approved effective treatment at this time. However IF it is true that sustained low blood oxygen and rapid breathing will contribute to deterioration in the lungs and/or other organs for those who do have COVID-19, then is it reasonable to suppose that supplemental O2 and/or other therapy at an early stage could be a benefit in those cases?

author: thm_w
author_rank: Super Contributor
timestamp: April 21, 2020, 10:15:38 pm
content: Quote from: calzap on March 29, 2020, 02:41:28 pmExcellent idea. I had ordered a max30102 to try this out. Although there may be some easy way to log via bluetooth on the finger reader as well. Would just need to wire 3V supply instead of using the batteries.Another thing you can do is get a night vision camera, do a motion-based recording of you sleep. You might see some very interesting things.Quote from: SiliconWizard on March 30, 2020, 04:03:33 pmSure, but which is easier to do, clip a $2 sensor onto your finger or figure out how to keep a mask on your face with an air pressure sensor in it?Of course if you feel it is necessary, going to a doctor and getting a sleep study done is best, but that is not really the topic discussed here (home health monitoring).Quote from: JBeale on April 21, 2020, 08:00:58 pmSee some of 'medcram' on youtubes videos. There potentially big benefit to treating early, to reduce the load on ERs, but how much of the funding and effort is going to that? Very little. Its no different from the usual approach to medical treatment, low or no level of preventive care, which ends up resulting in more emergency medical care later on.I don't want to get into potential prophylactics/treatments, this is not the forum to discuss medicine or health, you'll find better opinions elsewhere.

author: trophosphere
author_rank: Frequent Contributor
timestamp: April 22, 2020, 04:58:39 am
content: Quote from: JBeale on April 21, 2020, 08:00:58 pmThere is no question, even prior to the Covid-19 pandemic, that sustained hypoxia needs to be investigated.Quote from: JBeale on April 21, 2020, 08:00:58 pmAs you have stated, the problem lies more downstream in testing people who are suspicious for having a Covid-19 infection. At least in the US at this time the limiting factor is test availability and turn-around. If I want to refer a patient to get tested by the city's health department then I would have to present the patient's case to a physician employed by the health department who then would screen the patient themselves prior to the patient getting approval for testing. Similarly, if I wanted to have a patient tested in the hospital then I would have to talk to the medical director to plead my patient's case rather than me just ordering the test.I had a scenario about a month ago in which the patient got tested by the city in the morning but later that day developed worsening symptoms and thus had to go to the emergency department. The medical director of the hospital wouldn't approve of testing in the emergency department as the patient got the test already earlier in the day. The turn-around time for the Covid-19 testing done by the city's health department was realistically 4-7 days. The turn-around time for Covid-19 testing in the hospital was 3 hours. The patient was essentially in limbo until I had to hash it out with the medical director as he didn't want to use up another test as it was already done. The fact that I had to do it in the first place indicates the problem is with availability of test kits rather than trying to find candidates for testing in the first place.Supplemental oxygen is given to all hospitalized Covid-19 positive patients to bring their O2 saturation up to at least 90% (asymptomatic, non-pediatric) if they are not pregnant or to at least 92-95% is they are pregnant (or pediatric). As far as outpatient oxygen supplementation, there are no guidelines for Covid-19 patients currently in place outside of those with pre-existing co-morbid conditions resulting in hypoxia of less than or equal to 88% either at rest or during exertion.Bringing it back to the electrical side of things... I find that the MAX30101 and MAX30112 are really nice for near complete pulse oximetry solutions. Use the MAX86150 if you want integrated single lead ECG capability as well.

author: cdev
author_rank: Super Contributor
timestamp: May 04, 2020, 06:06:50 pm
content: Quote from: JBeale on April 21, 2020, 08:00:58 pmI live in an area that has a lot of COVID-19 cases right now and the hospitals here are not taking the cases they see as non-severe. Especially if they are younger and seemingly in good health without comorbid illness. However, if somebody who is actually having trouble breathing and is not otherwise able to articuate whats happening, is talking with them on the phone and they have additional information like a low oxygen saturation rate, that may be able to get them admitted - because its a quantitative measurement. Otherwise they turn them away telling them to call back and ask them again if it gets worse. The problem is sometimes they get worse very quickly and nobody knows why..One aspect of COVID-19 which is not getting media attention is theneuroinvasiveaspect of it.The SARS-CoV-2 virus like other coronaviruses, can and does use axonal propagation to gain ingress into the brain where it may infect the brainstem which can affect the ability to breathe automatically. Also it is a separate infection in many ways from the one in the rest of the body, like the lungs. So the state of the lungs may not be representative of this other life threatening infection because of the separation between the two. People lose their autonomous breathing - suddenlly, sometimes. It is usually several days in and this happens to both young and oldIt even happens sometimes when peoples lungs are not so badly infected or even infected at all. because it can infect the olfactory sensor neurons or cells in the cribiform palate that are able to serve as a pathway into the brain. There have been a lot of reports of people losing their sense of smell - As somebody who had asnomia happen (for about a year, decades ago) - not due due to COVID-19, due to toxic black mold (it returned eventually) this kind of thing is something I studied a lot to try to figure out what was going on then, and maintained an interest in since then. .So I am particularly interested in this aspect of COVID-19.One nurse who was infected described it like this. She felt as if she needed to stay awake becauseshe had lost her natural breath,I think the thing to take away is that we would be wise to hospitalize everybody who came down with COVID-19 who had any neurological signs like losing their sense of smell. They need some way of monitoring people who live alone or maybe everybody who is sick -some mass produced device that can wake people up and get them to start breathing again and call the ambulance if they stop breathing.Otherwise people die in their sleep when they were told to wait it out at home, here in the US, large numbers of people are dying at home because of this mess.And this is an astronomical loss to society. We have to do much better than we are doing.Its NOT the medical professions fauilt, we need to face the reality that this kind of thing is going to happen more and more due to the rising levels of interconnectedness and we have to make it our business to respond to it with science.I personally am trying to get the medical profession to look at a particular substance, one thats found in wine, peanuts, grapes, blueberries and an invasive plant that people comonly go nuts trying to eradicate, as a potential aid to this illness. Its already in the supply chain. It's the best known of the stilbenoid polyphenols. It was literally the first thing that came into my head when I heard what COVID-19 was doing. (Because it has all sorts of activities against things like sepsis and the verious respiratory issues caused by (symptoms) caused by other pathogens so much that it seemed a represent a remarkable match AS FAR AS I COULD TELL, superficially, it seemed to match closely to the problems COVID-19 causes) BUT, not being a doctor I have to say, sick people should not take it or anything else that they dont have medical advice is safe, when they are sick, please don't take it rely on doctors even though its remarkably safe in healthy people, considering the issues it often seems to improve.There is a missing hole in our knowledge there.It was shown to inhibt either one or both of the other two most closely related betacoronaviruses - in vitro, and it also does with many others. Its been used successfully in animal experiments for example, in piglets when put into their feed, preventing potentially fatal infections with pseudorabies virus. Piglets treated with it survived while others died.Its cheap enough to be looked at as a replacement for antibiotics in agriculture. So the manufacturing capability is there.We need to think outside of the box.So, to return to my original thought, we should improve our ability to monitor sick people and make calling the doctor automatic, and then we can safely allow them to stay at home unless they are really in need of care and then give it to them. Because we'll know that if their respiratory ability starts failing at night because of COVID-19 invading their CNS a few days in, that will summon help.And before and while they are sick we can give them things to reduce the disease severity even if not a silver bullet they could likely reduce the deaths and injuries a great deal. Whatever works, We should be doing our best to figure out what works.

author: Buriedcode
author_rank: Super Contributor
timestamp: May 04, 2020, 07:23:31 pm
content: If you're talking about Resveratrol, or similar compounds, the wikipedia page doesn't provide any evidence for any benefit in humanshttps://en.wikipedia.org/wiki/Resveratrol#LifespanIts main proponent apparently falsified data:https://en.wikipedia.org/wiki/Dipak_K._DasLooks like another drug that quacks have jumped on as a cure-all

author: cdev
author_rank: Super Contributor
timestamp: May 04, 2020, 09:24:09 pm
content: Resveratrol is NOT a "drug".There is a urgent need to find a way to reduce the huge numbers of good people who are dying from a disease that is bringing many down before their time.Your profile says you live in or near London. I currently live near NYC. Both areas with their share of air pollution.Even if they dont know why it has this effect, given that there seems to be a link between high COVID-19 mortality, and pollution (such as NO2 and PM2.5), shouldnt we investigate a substance known to be useful in reducing the impacts caused by a lifetime of exposure to air pollution?Here is a proposal. Give me a short list of five serious problems that COVID-19 infections cause. Life threatening problems are fine. I'll show you why I think we should look at RESV. Not use it, (Until it was shown that it worked) just looked into it.Let me try to show you why I think people would be smart to investigate it.in order to support the point I was trying to make. Okay?Also I have never heard of your "main proponent". Wikipedia is not where I go for health information.I read papers in the literature. When I have questions I email authors.

author: VNUTDENYER
author_rank: Contributor
timestamp: May 15, 2020, 10:29:54 am
content: Just a short return to OP. When I was walking every AM, few years ago, would suddenly have to stop due to Zero energy. Got pulseox and next day saw 78Waited minute or so and reading went up to normal, for me, of 95-97. Only happened couple times, quit walking also. Later sleep study confirmed apnea which is now controlled with CPAP. After 30 days good readings insurance will cover monitor o2 at night (medical profession assumes if breathing normal o2 will be normal).