DeltaDave: Are 3% desaturations harmful even if above 90%?

[SleepingUgly]

Dave, what does research tell us about the health risks of "desaturations" (defined as 3%) if the overall SaO2 is 92% and higher? Thanks!

[themonk]

SU, I am not Dave, but I do recall reading a pubmed link about milder desats not having the same impact on cardiovascular health. I don't think the link below is the one I read, but it comes to the same conclusion.

This is actually really important to me because my lab used the 'alternative' hypopnea scoring which snagged me as having apnea. Had they used the 'recommended' criteria, I wouldn't have been diagnosed. I know my results are pretty rare in the apnea world - no apneas and only mild hypopneas, but it would be nice to see more research around us outliers.

http://www.ncbi.nlm.nih.gov/pubmed/18276938

[SleepingUgly]

That article doesn't appear to look at desats of 3%.

[themonk]

I assume less than 4% would include 3%

"Hypopnea measures based on less than 4% oxyhemoglobin desaturation or presence of arousals showed no association with cardiovascular disease."

"In contrast, no association was observed between cardiovascular disease and hypopneas associated with milder desaturations or arousals."

[jnk]

Until Uncle Dave arrives with a real answer.

The transient amount of O2 in the blood as compared to a baseline can be used to measure the significance of a breathing event. That is one thing. It is used to score events that may be impacting sleep even when no arousal is recognized in direct connection with the event. That is important, since sleep is important to overall health. That is a desaturation in the context of scoring events in sleep medicine.

On the other hand, the sustained amount of O2 in the blood over a much longer period of time, particularly below 88% or so, can impact health separately from damage to sleep architecture, since those desaturations can lead to eventual damage to organs from, for example, not enough O2 and too much CO2 in the blood, for long stretches of time overnight. That is desaturation in the context of breathing as it relates to medicine overall, not just sleep medicine.

That is my understanding as a patient with no medical training in anything whatsoever.

[SleepingUgly]

I assume less than 4% would include 3%

"Hypopnea measures based on less than 4% oxyhemoglobin desaturation or presence of arousals showed no association with cardiovascular disease."

"In contrast, no association was observed between cardiovascular disease and hypopneas associated with milder desaturations or arousals."

My sleep report notes how many desats of 3% (or more) I had. I can't tell how many of them are 3% vs. 4% or whatever. So I don't feel "safe".

[jnk]

"Breathing abnormalities and transient arterial desaturation during sleep are relatively common in normal healthy people."-- http://thorax.bmj.com/content/35/2/81.full.pdf

[themonk]

My sleep report notes how many desats of 3% (or more) I had. I can't tell how many of them are 3% vs. 4% or whatever. So I don't feel "safe".

Interesting and now I see why you are asking. I wonder if you could get that data parsed out a bit? If they are reporting 3%, they must be using the 'Alternative' criteria for hypopnea scoring. Maybe they also track 4% since it is another possible scoring option.

My sleep study report only lists the number of 4% or greater which was low in my case, but they count 3% in the scoring (yeah, odd). It would be nice if sleep labs would be more uniform in their reporting. I can see the usefulness in having all desats categorized with the duration also reported.

The link I provided shows that there is at least some level of variance in the damage done between 3% and 4% desats. I think this is important because it starts to better define what apnea does and doesn't do in specific cases. I think apnea is treated too generally and everyone is lumped together, but that clearly isn't the case. So hopefully it helps a little, understanding that your question is a bit different.

Anyway, I look forward to DD popping in since it is very much of interest to me.

[SleepingUgly]

The other caveat is whether 3% desaturations are harmful WHEN the overall SaO2 doesn't drop below 90% (or in my case, 92%).

[DD's Alternate]

My sleep report notes how many desats of 3% (or more) I had. I can't tell how many of them are 3% vs. 4% or whatever. So I don't feel "safe".

its not considered a desat until it reaches 3%

[greatunclebill]

this thread got me thinking. i have what i think are alot of desats and pulse changes. what is your reading on this report?

[ldj325]

This pertains to the post of greatunclebill.

I don't want to go into detail as I don't want to side-track this thread, but unless you've had an ECG recently you might want to get one. The CMS devices are good value devices for the average person, but can show significant errors in the presence of heart rate/rhythm issues.(I base this on direct experience having a CMS wristox that was reporting faulty data that was revealed once I compared it to a hospital grade Masimo Radical 7 oximeter.) IF your CMS data is relatively accurate you are close to the threshold for tachycardia. And if you have Afib or other rhythm issues then that could easily "throw" off the CMS in its reporting. Hopefully it is nothing, but catching rate/rhythm issues earlier rather than later is a good thing.

[deltadave]

... what does research tell us about the health risks of "desaturations" (defined as 3%) if the overall SaO2 is 92% and higher?

Interestingly, these guys looked at SHHS data a little differently:

In particular, RDIs that are derived by including hypopneas with either a 3% or 4% desaturation appear to predict hypertension almost equally well.

Jointly considering indexes capturing event frequency (eg, OAHI3P) and overnight hypoxemia (time spent at an oxygen saturation < 90%), however, slightly increased the prediction of blood pressure, compared with either index alone.

Polysomnographic Predictors of Blood Pressure and Hypertension: Is One Index Best?

[greatunclebill]

This pertains to the post of greatunclebill.

I don't want to go into detail as I don't want to side-track this thread, but unless you've had an ECG recently you might want to get one. The CMS devices are good value devices for the average person, but can show significant errors in the presence of heart rate/rhythm issues.(I base this on direct experience having a CMS wristox that was reporting faulty data that was revealed once I compared it to a hospital grade Masimo Radical 7 oximeter.) IF your CMS data is relatively accurate you are close to the threshold for tachycardia. And if you have Afib or other rhythm issues then that could easily "throw" off the CMS in its reporting. Hopefully it is nothing, but catching rate/rhythm issues earlier rather than later is a good thing.

thank you for this. you didn't mention the o2 sats. does that mean the o2 part is ok? as to the heart i did have an ecg (echo) when i was in the hospital with pneumonia a couple weeks ago. basically it was the last thing done before discharge. i had to wait til the cardiologist said the ecg was ok before i could be discharged. i was not on monitors during the stay. i have no known heart issues. about 10 years ago in a regular doctor visit they thought they saw an a-fib. i was sent directly to icu for about 3 days. they said no a-fib.