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CPAP and pitting edema (fluid retention)
CPAP and pitting edema (fluid retention); A layman's explanation
[parts of this thread copied from our old fourm] - started by Clumpco
Clumpco wrote:

Hi Folks,

Now two months down the line and still getting a good AHI (< 1 most nights), however I have started suffering from high blood pressure (160/90) and pitting edema of my feet, ankles, calves and forearms. This got to be pretty painful so I went to see my doctor (or rather his young locum since it is the holiday season) who prescribed a diuretic, support stockings and to sleep with my legs elevated.

At the same time he prescribed full blood work. My heart is in perfect shape (visit to the cardiologist just before being diagnosed with OHA) and my blood work came back all in the green. The treatment is helping, but the problem hasn't gone away.

A bit of Googling revealed that I am not alone in suffering from pitting edema/fluid retention after starting CPAP therapy, so I questioned both the Doctor and the lung specialist about this. Both said that they had never heard of any link between CPAP and edema. This seems to go against what some CPAP users are experiencing.

I have seen some explanations on various forums that do not satisfy me (it's the water from the humidifier!) so I had a closer look at one of the symptoms of OHA - nocturia. Nocturia is voluntary urination during the night and is a common symptom of OHA - in fact in younger sufferers it is often considered to be the principle symptom. Nocturia is caused by increased levels of the atrial natriuretic peptide hormone (ANP) which is secreted by the heart when it gets the (false) signal that there is too much fluid in the body, caused by the increased pressure in the right side of the heart from OHA events. In my case I was definitely suffering from nocturia, in the weeks before being diagnosed when the symptoms were getting worse and worse I was rising every hour to urinate and had been rising at least twice a night for at least a year before that.

Now here's my take on what happens... Successful CPAP treatment has an immediate effect on ANP production from the very first day of treatment - no more apnea, no more high pressure signal in the heart, no ANP production. This abrupt change in fluid evacuation must have an effect on the body which has been used to getting rid of fluid both day (normal) an night (abnormal), as a result there is fluid retention which will probably correct itself slowly as the body re-adjusts to the normal day/night cycle of urine production.

I hope that I am right and that this will gradually clear up - I have no wish to wear support hose and take diuretics for the rest of my life.

I would be most grateful and interested to have everyone's opinion on this - maybe someone with more medical knowledge than I could tell me if I'm talking total tosh or not.


Ltmedic66 wrote:
I am a little stumped, but i do have a thought. I wonder if your edema is not due to too much fluid, but rather insufficient cardiac output. Edema is often a sign of right sided heart failure, but perhaps there is something related to CPAP.

Here's my thought- perhaps the increased pressure within your chest cavity is putting some pressure on your heart, which then prevents it from being able to refill completely before contracting. Do a search for pericardial tamponade, and you'lll kind of get the idea. When the heart is not able to pump efficiently, fluid can back up in the body, often in the legs.

Of course, I think distal edema is worth very aggressive medical evaluation to rule out cardiac or renal issues.

Quote: [Ltmedic66 wrote - When the heart is not able to pump efficiently, fluid can back up in the body, often in the legs]

Clumpco wrote: OK, but wouldn't this mean that the edema would be at its worst in the morning? (In my case it gets worse as the day goes by).
Ltmedic66 wrote: I would think it would be worse in the mornings. Pitting edema is a pretty severe finding under most circumstances. Again, I hope you are aggressively seeking medical advice.
Clumpco wrote: ll appears to be slowly improving from a combination of diuretics, raised legs while sleeping and wearing support hose during the day.
BP is down from 160/90 to 140/75 and if I remove my support hose in the evening there is no immediate swelling.

I am waiting for my usual doctor to get back from vacation, but my blood work from Monday is all in the green (thought platelet count is a little low, I put this down to fatigue). I even had the new (here in France) Brain Natriuretic Peptide (BNP) Test which gave a result of 1 pg/mL which appears to be very good.

Coming back to my theory about ANP, what bothers me is that I am not alone in having fluid retention symptoms after starting CPAP therapy and nor am I alone in finding that medical specialists think that there is no link. My heart has been producing ANP every night for months (or years) and this has suddenly stopped - I can't imagine the body adjusting to this overnight (sic). If I went to my doctor and told him that I had been taking diuretics every night for the last two years and had suddenly stopped and was now experiencing oedema, I am sure that he would immediately make the connection.

Concerning sleeping position, I sleep mostly on my left side - though I do try to fall asleep on my right side due to years of conditioning by Mrs Clumpco because of my (pre-CPAP) snoring - I still usually wake up on my left side. Interestingly my sleep study showed that the apnea was 2x worse when sleeping on my left. As mentioned above I have now raised my legs in bed (we have an electric bed-base) but I cannot put them too high due to me sleeping on my side. I cannot sleep on my back for two reasons: 1) I can't manage to fall asleep on my back, and 2) I have a herniated disk which causes my legs to go numb if I remain on my back for more than 15 minutes or so.

anneliza wrote:
In my case, I had edema all up my legs to the rest of my body before I was diagnosed with sleep apnea. Since the CPAP therapy, although I no longer get up to pee every hour, I have had less trouble with it. I have always had a tendency to retain water, especially my ankles will swell up if I sit all day at work behind the computer. It improved partially with CPAP therapy. I have been making sure to eat foods with plenty of potassium, and take some garlic and dandelion supplements to support the kidneys, and that has helped. My blood pressure was very high before diagnosis, and is slowly coming down. I have been on CPAP for three months, and although the daytime sleepiness and nodding off while driving cleared up almost immediately, other health problems are clearing up, but more slowly. I think it takes time for the body to build itself back up after months or years of lack of sleep and lack of oxygen in the night. It's only in the last three to four weeks that I have noticed improvement in edema and blood pressure, as well as energy. I am finally able to get some good walking in -- I was too exhausted and breathless until recently, and of course exercise should help with blood pressure and edema issues also.

Doing without sleep or good breathing is devastating to the body. A coworker of mine was diagnosed last year with sleep apnea, and died in her sleep before treatment could begin. I would think it would take quite a bit of time for our bodies to fully recover. We probably all suffered from adrenal exhaustion as well, due to using so much adrenaline all night, every night to kick start our breathing over and over again. Eat well and give it time to heal.

archangle wrote:
I sleep in a recliner. When I visited my dad, I would get edema in the legs after a few days. I switched to sleeping in a different recliner at his house and the problem went away. I assume it has to do with cutting off circulation in my legs.

Perhaps experimenting with sleeping position, leg position, pillows, etc. can help. Maybe some CPAP patients sleep longer in one position than they did before and circulation is affected. Maybe if you sleep on your side, and make an effort to turn over sometime during the night, it would help.

It's cheap and simple to try.

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The effect of continuous positive airway pressure (CPAP) on renal vascular resistance: the influence of renal denervation
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Hey, Zonk, thanks for the past writings and the link...very informative.
If I read the link correctly, it suggests a low correlation between CPAP use and Urinary response....what's your summary?
--==<< old, experienced, but still curious >>==--
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Interesting! So there does seem to be some sort of connection. Off to read Zonk's link.
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I have water retention too and it began after my c-pap therapy as I recall. If I don't eat any salt or at least very little I can keep my ankles and lower legs from swelling. My hands too get stiff and my rings get tight. Just eating low salt rice cakes can give me extreme swelling. Low salt is not low for me. All frozen, canned and boxed foods are too high in sodium for me. I hate diuretics and think they are bad for the kidneys. My B/P gets high of course and blood pressure pills lower me too much but leave the edema. I am allergic to Hydrochlorothyizide and get itchy welts, blurred vision and other problems. Lasix is scarey and worse side effects. Seems I am some what doomed.
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Hi zonk, Thanks for posting this information from the old forum and also the other link, very interesting.
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Bump2I'm having this problem too.
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Also me.
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Zonk, thanks for reposting that link. I read the article, although it assumed I would know how much edema would be produced by various increases in renal resistance, and I don't.

I started CPAP on April 3, and noticed no edema. But about three weeks ago I started a low dose of amlodipine. A week after starting it I noticed one morning that my shoes were tight. I looked down at my feet and it looked like I had developed elephantiasis. A quick Google search revealed that edema is a common side effect of many calcium channel blockers, amlodipine being one of the worst (about 7% of patients). I immediately stopped the amlodipine, but that was a couple weeks ago and the edema has gone down only slightly. I had no edema before starting the amlodipine, even thought I had been using CPAP for a couple of months. Now I am wondering if there is a connection between the CPAP and the amlodipine, that is, maybe they hype each other's edema production, like a drug interaction.

I should add that for over a year I have taken a high dose of furosemide (Lasix).

I asked Mr. Google how long it takes for edema to go down, but he failed me. I also tried to find out the method of action that makes amlodipine cause edema, but Mr. Google failed me yet again. I wonder if it also increases renal resistance like the article mentioned for CPAP.

The edema continues to abate, albeit very slowly. I am otherwise healthy and happy and my kidneys always test in the middle of the normal range, so I'm just going to give it more time. But if it stops going down I'm going to have to see my PCP to figure out what to do about it. Thinking-about
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You will need to put your feet up high for as long as you can. Like on a wedge pillow at night or up on an ottoman or recliner while sitting.

Pitting edema is when you press your finger into the swelling and it forms a dent that does not immediately go away.

"Regular" edema is swelling with no pitting.

Pitting edema is a quite serious problem and is the major symptom of a blood clot in the legs. It is a symptom of many other things as well but blood clot is the first thing most docs assume. This is especially a concern when the patient has recently flown in a long airplane flight, taken a long car ride, or engaged in more sitting (or even walking) than usual AND is accompanied by pain in the legs.

I recently flew to Minneapolis where I spent 7 days sitting a lot. I then flew back where I have done more sitting than usual. Then I took a 12hr car trip. Since then, my feet are quite large at night. By morning, the swelling is gone because I've had my feet up. We check my ankles in the morning and if they are still fluffy, I'll put them up on a pillow. This rarely happens though. I am quite sedentary and swelling is a more and more regular issue.
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