When I was pregnant*, my blood pressure went up toward the end, and my feet swelled in a big way (it didn’t help that it was summertime, either). How, on a cellular level, does that happen? Was there more water in my blood? In my skin cells? Why feet more than other body parts?
And what is the link between high blood pressure and edema, anyway?
*2 years ago… I blame the baby brain for not wondering about it until now.
Don’t know about the BP and edema, but I do believe that your total blood volume increases by quite a bit.
Edema (Basically the swelling of tissues) can have many different causes. Since you asked about the relation between blood pressure and edema, that is what I am going to explain.
Basically, blood pressure is the measurement of how much force is being placed on the sides of your blood vessels by your blood. Blood travels from your heart, into arteries, into arterioles, and then into the capillary beds, where the actually exchanges take place. The capillarity walls are very thin (which allows the gas and nutrient/waste exchange to happen), and normally some of the water component of the blood leaves the blood, and goes into the tissues, some of it stays (This is actually also the main source of lymph), but most of gets reabsorbed into the blood vessels. As your blood pressure goes up, there is more force pushing the water into the tissues. Since more water is leaving your blood vessels, and the reabsorbtion rate stays about the same, the tissues start to swell… Causing edema.
Hope that helps.
(Missed the edit window)
Oh, I said I would focus mainly on Edema caused by BP, but I just wanted to mention that the other major cause for edema, congestive heart failure, is basically caused by the same idea. As the heart fails, it doesn’t pump enough blood, and the blood starts to back up behind the failing chamber (Left side backs up into the lungs, right side backs up into extremities). As the blood backs up, there is more pressure on the walls, and again, more water leaves the blood then is reabsorbed into the blood, causing edema.
I don’t mean to be a stickler, but this is not correct. Arterial blood pressure (which is what is referred to when we talk about high blood pressure) is NOT acting to force water out of the capillaries or venules. It is the pressure in the veins (venous pressure) that provides the driving force pushing water outward (so-called hydrostatic force). One of the most common causes of high venous pressure causing edema is heart failure wherein blood, in some sense, “backs up” from the heart leading to high pressure in the veins.
In addition to the hydrostatic force tending to push water out of the venules and capillaries, there is something called the oncotic force trying to hold it in. Basically, the proteins in your blood act like a sponge and hold on to water. If the protein level is low, there is less of this sponge-like property so water leaks out of the capillaries. This is common in people who are very malnourished or who are very “sick” (say with overwhelming trauma or infection).
A third generic cause of edema is damage to the capillary wall itself (or deranged function of the wall such that it allows water to leak out).
I apologize for the brevity of my answers but I’m a bit busy at work now.
So … I think my question sort of fits in with this general vein [heh]
II have a friend on furosemide … and we hang out a lot, and discuss our health issues.
She makes an effort to get the requisite 64 oz of water per day, and watches her salt consumption. She doesn’t seem to have any issues with edema but her doctor wants to put her on lasix [furosemide] She is in good health for being fat like me … no kidney problems, and even her doc says she is in pretty good health for being fat.
So why in hell would they put someone on furosemide?
When I had it to shed the excess calcium in my system, I peed like every 10 minutes… I almost wanted to set my computer up in the damned bathroom…
I could see it if she had edema problems, but she doesn’t…
Not sure . . .
You’re quite right that it’s used for edema treatment primarily. But remember, some edema may not be visible, e.g. edema in the lungs (pulmonary edema, virtually synonymous with heart failure). Might she have that?
Another use for Lasix is as an adjunct to control big time high blood pressure. In such a circumstance, though, the furosemide is usually one of three, four, or even five blood pressure meds. Further, it’s far more likely to be used to treat high BP in the setting of kidney disease. Could that be an issue?
Finally, as you noted, furosemide can be of (very modest, if at all) assistance to lower blood calcium levels? Is that a consideration?
Bottom line - I haven’t a clue.
She is healthy, just fat … I have checked her BP and it is better than mine. She was wondering. Like I said, she watches her health [she is in the process of losing weight and controls what she eats and drinks] and I could understand it if she just sat around and drank soda all day, but she is being very careful, not even artificial sweeteners just plain water.
Oh well … I know that I hated the damned med when I had to take it. She has an appointment with her regular doc now he is back from vacation and will be asking him about the lasix. She really doesnt want to take it - she saw how much I hated it.
I do not know why they are putting her on it, but I am on furosemide and I am not experiencing anything like the unpleasant effects that you describe. I might have to pee two or three extra times during the first couple of hours after I take it (once a day only), but it really has not bothered me. Not everybody is going to react the same to a drug I guess.
Of course, there’s another way for non-blood fluids to make their way back from the extremeties. The lymph system, with its tubes and nodes, takes care of part of it. I won’t guess how pregnancy might affect the lymph ducts.
In some cancer surgeries, nearby lymph nodes are removed to check for spread of the cancer. Some women, after breast cancer lumpectomies, end up with lymphedema in one arm. The lymph system in that arm no longer works, so the arm is permanently somewhat swollen. During exertion, that arm will sweat profusely.
I do not presume to know anywhere near as much as KarlGauss about human physiology, but I’ll take a stab at elaborating a little until such time as he can form a lengthier response. Deranged function of a sort may be caused by histamine, which is released by mast cells in response to antibody-antigen binding (as in allergies or appropriate immune response). Histamine causes both capillary vasodilation and an increase in capillary permeability to proteins. As proteins leave the capillaries, they increase the oncotic pressure in the tissue, causing water to follow by osmosis.
You sound pretty damn knowledgeable to me! Your comments about histamine are right on and are a great example.
So, there are capillaries in… muscle tissue? (I guess that’s what I don’t get - what tissue in my feet was holding all that water?)
Thanks for explaining all this - this is fascinating!
There are capillaries in every bit of the body that needs oxygen to function. The only tissues that do not have capillaries are relatively inert stuff like cartilage and tooth enamel.
The fluid goes to your feet because of gravity. If you stood on your head, it would go to your head. There’s nothing special in your feet that attracts the water- it’s just that they are closer to the ground.
I have seen several horses over the years with the complaint of “swollen head” - the owner brings the horse in at night and its head is swollen with edema. In the morning (when the vet arrives usually) it looks normal. They can go back and forth like this for a while - swollen head in the evening, normal when the vet comes out the next day. What’s going on is that the horse has a disease that causes very low blood protein. When the are turned out they graze all day and, since their heads are lowered, the edema accumulates in their head. Then, they stand in the stall at night with their heads up and the edema goes away.
An increase in blood pressure at the end of your pregnancy usually just means your body has reached it’s maximum circulatory volume. Typically, an expectant mother’s blood volume, near term, increases by 50%. With such a large increase in volume, and without a relative change in your blood vessel size, your pressure will be somewhat higher.
This is normal, and is usually not a cause for alarm. In fact, the blood pressure typically returns to a normal level when labor contractions commence. The cause for alarm, however, is when signs and symptoms of pre-eclampsia develop. Just based on your desription, you may have developed this.
There are many theories on its exact cause, but nothing conclusive has been established. However, with routine and proper prenatal care, pre-eclampsia is screened for, and can be minimized or even prevented. The edema is usually caused by a lack of protein, general malnutrition, or sickness (as KarlGauss has already pointed out).
A lack of protein causes the body’s cells to leak fluid. This fluid leaks into the tissue which appears as edema. And, gravity being gravity, the fluid travels to the most dependent parts of the body, namely the hands and feet, with the feet in more greater amounts. (Although, sometimes it appears in the face as well.)
A well balanced and proper diet plays a significant role in preventing pre-clampsia. There seems to be a consensus that an expectant mother should take in at least 70-90 g protein daily, along with complex carbohydrates, and fruits and vegetables. And, obviously, drinking lots of fluids should be done on a regular basis, especially in the summer months.
Hope that answered your question.
Thanks - I knew about the increased blood volume, and pre-e, and I definitely didn’t have it - but I might have developed it if my son hadn’t arrived a couple of weeks before his due date.
And I did not know that there were capillaries all over! So there was excess fluid in the muscle tissue and skin tissue and wherever else in my feet - that’s what I was wondering.
I knew that gravity was making it go to my feet, but I didn’t know where in my feet it was all hiding.
Thank you all for your answers! My curiosity is sated.