Leg edema when CPAP goes to higher pressure

I have come across other references to people developing edema after starting CPAP. I just started CPAP the beginning of April and I was loving it (Airsense 10 For Her). My pressure averages just over 6 and with that my AHI went from 45 to less than 1. I am tall and thin and have joint hyper mobility, but do not fit the definition of full blown Ehlers Danlos Syndrome. I suspect that my loose connective tissue is what gives me sleep apnea as my soft palate falls back very easily. That would also explain why such a low pressure works for me. Anyway, in midMay I woke up to find both legs quite swollen (pitting edema), something I had never experienced before. I had been having trouble with my nasal cushion fitting properly that night and when I glanced at the pressure during the night it was between 10 and 11, something I had never seen before. A curious thing about the edema is that it got better during the day. Usually you would expect leg edema to get worse during the day because of the legs being “downhill” from the heart. I struggled with mask fit again the next night and the edema continued (not sure of the pressures the 2nd night). I then got a new nasal cushion, had a good fit, pressures seemed to stay low and my leg swelling went away over the next 2 days and has not returned. I have also turned off EPR and gradually lowered my maximum allowed pressure (it is currently set to 7.) My AHI was 0.3 last night so I feel comfortable with that but will continue to monitor.

I have not been able to find any info on the web about this other than people who posted here a couple years ago with similar stories, except that their swelling started right away with CPAP. My best theory is that because I have very loose connective tissue, the increased intrathoracic pressure when the CPAP pressure went up led to decreased filling of the right atrium and therefore a backup of fluid most noticeable in the legs.

I did have a normal echocardiogram in January and have no heart disease. The swelling did not cause any breathing problems either. I would love to hear from anyone with similar experiences.

First off, to be clear I am not a doctor. I have used CPAP for a couple of years and my wife longer. I can't think of any direct way leg edema could be caused by the CPAP. I would be looking other potential causes like a blood pressure medication such as amlodapine. A water pill like indapamide may be a better alternative. There are a few other drugs which may cause it like Actos and Avandia for diabetes. Congestive heart failure can also cause it.

Have you used OSCAR to look at your AirSense results in more detail? It may offer some clues as to what may be going on. Low blood circulation can cause central apnea. If you are having central apnea events that may be a potential cause.

I actually am a doctor myself and it does make sense that a high enough pressure inside the chest cavity can restrict blood flow return to the right atrium. The question is how high a pressure is needed to do this? In most people it is obviously much higher than the usual CPAP pressures. In my case I am speculating that because of my weak connective tissue my vena cava partially collapses more easily, thus restricting blood return. I agree that the meds you mentioned can cause leg edema, but the only medication I am on is low dose beta blocker for sinus tachycardia. Not to mention the fact that the swelling has resolved completely and not returned since I have kept the pressure below 8. My most recent results showed 0.2 AHI, 0.1 central. I am getting the data from the clinical menu, I’m not familiar with OSCAR but will check into it. Thanks!

I'm hoping that you've found some information since your original post... I'm new to my CPAP (AirSense 11). AHI was 70 (!!), with a mix of (mostly) OSA and CSA, down to less than 2. I've been using it since 2/14 and, other than obesity, have no chronic issues and take no medications. I've only ever experienced LE edema sporadically during long distance car travel (10-12 hours). Currently, I have my settings at: auto ramp at 4 and it runs up to 11 overnight. I use nasal pillows with zero leaks and have had no adverse issues until this started over the last week. This was the only information I've found regarding increased LE edema with CPAP use!

There have been many discussions on the apparent link between CPAP and Edema, but for us mere mortals it seems way too complex to really get a grasp of.

Inevitably they must be connected, but then everything that impacts on the body is connected to everything else via one mechanism or another.

Just being human and ageing would link everything even if it is through numerous interactive systems.

In many ways sleep disorders are central to, and perhaps even pivotal to, a wide range of other disorders.

From a different perspective, even considering that there might be a link forms a link and certainly acting on those beliefs creates direct links and quantifiable effects.

The question isn't: "Are they connected?" but "How are they connected?" and "How do we co-ordinate the treatments?"

Something else to ponder at 4am.

:P

Just wanted to leave an update re: leg edema developing overnight and resolving during the day after starting CPAP and pressures went higher. I eventually settled on putting my machine in CPAP mode with a pressure of 4.5 and remarkably that has given me great control of my apnea with (AHI) almost always less than 1. I have had absolutely no recurrence of the nighttime leg edema since keeping the pressures low. I do have a little daytime edema from bad veins, but this, as expected, gets better overnight.

I know I still have apnea to treat because only when I occasionally take off the CPAP in the middle of the night, my Fitbit shows a spike in my oxygen variability.

Obviously most people tolerate and need much higher pressures than this, so I can only assume there is something different in how I am “put together”. I talked about this in my original post. I suppose if I really wanted an answer I could let the machine go back to a higher pressure and see what happens but I find that prospect a little frightening and have decided to leave well enough alone.

And as a note to those of you who have reasonably suggested other causes of leg edema (eg medications or heart failure): in these situations the edema is always worst at the end of the day and best in the morning as having the legs elevated helps them “drain”. My situation was the exact opposite.

I am a dentist working in dental sleep medicine. Have you considered switching to an oral sleep apnea appliance. There is zero pressure required. You could also consider wearing an oral appliance WITH your CPAP. That would lower the required pressure even more. Dr. Arthur B. Luisi,Jr., The Naples Center For Dental Sleep Medicine.

Thanks for the suggestion, but I already have my pressure set as low as it will go so not much to be gained there. I have also over the last year or two developed an enlarged tongue which definitely reduces my oral airway and it’s hard to imagine any tolerable oral device could counter that. I have had a thorough medical work up, including biopsies, with no explanation for the enlarged tongue(I’m not overweight either). Looking back, this tongue enlargement may be the cause of my sleep apnea. It now protrudes over my lower incisors and pushes up against my upper incisors. It overlaps my molars. It has shifted my bite. With my nasal CPAP on I no longer even have to sleep with my mouth closed as my tongue easily seals off the back of my airway when breathing through my nose. I’m a little worried as to what will happen if my nose is blocked from a cold.

Well, I admit that it seems that you are really boxed in. I think that you have done what you can to mitigate the situation. Your only other option is the Inspire system, if you qualify. This is significant surgery, but I can't think of anything else. Dr. Luisi