Internal Gravity

Gravity works inside the body as well as outside. That low spot on your driveway or sidewalk stays wet even after the rain stops because the water seeks the lowest level. Your lawnmower ends up in the mud and chopping through thick wet grass for the same reason. Inside the body is no different. After the storm (i.e., the injury), things will settle before they subside.

Two of the most common ways this plays out in the ER are a medical condition (e.g., heart failure) and trauma or surgery. (Surgery is akin to controlled trauma under sterile conditions.)

Let’s talk about heart failure first. From a 10,000’ view, heart failure occurs when the heart does not pump as well as it should. There can be problems with how the heart fills, how it squeezes, and it may affect either or both sides of the heart. The left side of the heart pumps blood to the body. That blood comes back to the right side of the heart, which pumps it to the lungs. It offloads CO2 and picks up O2 and comes back to the left side to be distributed to the body, and so on and so forth…

(Again, I’m speaking in generalities here as the nuance and details of heart failure are not the point of this post.)

If the heart is not pumping well, it’s somewhat like your sump pump not working. What happens to the water level if you have a sump hole in your basement? It fills up and the water backs up into the drainage system under your foundation. The system can tolerate some level of backup, assuming the sump pump is fixed, i.e., the breaker gets reset or it gets replaced. Life goes on.

But if you are on vacation when this happens, you come home to soggy carpet and warping baseboards. The vascular system can only tolerate so much as well. If the pump continues to not work well enough, the fluid starts to leak out of the vessels and gets deposited elsewhere. Namely, if the left side of the heart isn’t working great, fluid accumulates in the lungs. The fluid in the lungs distributes into the lungs themselves (pulmonary edema) or around the lungs (pleural effusions). And the fluid goes to the dependent, or lowest, part of the lungs. This is often why patients with heart failure can breathe easier when sitting up. When they lie flat, the fluid disperses more through the lungs and towards the back of their chest cavity. When they are upright, it tends to be in the lower part of the lungs and under the lungs on top of the diaphragm.

If the right side of the heart doesn’t pump well enough, the fluid essentially gets squeezed out of the veins in the lower extremities and into what is called the interstitial tissues. This causes lower extremity edema. And you may have guessed it: it generally starts in the lower legs and feet and ascends up the legs as it worsens. Patients that are bedbound or nearly bedbound develop edema in the back of their legs and buttocks because that’s the lowest part of the body.

The problem is not the vessels or tissues in the legs, at least not in a way that is fixable by removing the fluid externally with a needle or specific medicine that draws it out from that precise location. The treatment is usually diuretics, which increase urine production. Eventually the fluid is reabsorbed into the blood, which gets filtered in the kidney and excreted, but it takes time.

There are other heart failure treatments as well for more severe symptoms, but that is beyond the point of this post.

Conservative treatment besides medications includes elevation and compression stockings. Elevation is a double-edged sword because of the anatomy of the vessels and vascular system, including lymphatics. There are no muscles in the venous system (the system that brings blood back to the heart) or lymphatic system (the body’s drainage and defense system). For forward flow to happen in those systems, and by forward flow I mean back to the core or heart, muscles surrounding those vessels need to squeeze. This is the point of compression stockings.

But you know what else causes muscles in the legs to squeeze? Yep, that’s right: walking. Movement. I tell patients with lower extremity edema from pretty much any condition, elevate your feet when seated. Don’t leave them down sitting at the kitchen table or in the recliner all day. And certainly not when sleeping. But also, don’t sit around all day. Walk, move, get as much exercise as possible. The muscles need to squeeze to help with edema.

As heart failure patients get worse, patients often sleep in a recliner because breathing is easier. This makes the lower extremity edema worse if the legs are left down all night.

Now let’s turn our attention to trauma and surgery. Head trauma that results in a hematoma or swelling is a perfect example. It can be anywhere on your head and very minor to quite severe and concerning. When I say concerning, I mean it looks concerning. Some patients have told me that if you get head trauma and it doesn’t swell out, it swells in. This is often the concerned parents of a toddler who took a tumble and has minimal external trauma and the parents think he must have an intracranial disaster despite him running around, playing, being active, acting normally without headache, or nausea and vomiting.

No, if it doesn’t swell out… it just doesn’t swell out. It has nothing to do with swelling inside.

A hematoma is a fancy word for a collection of blood. When this happens under the skin, particularly on the head, because of the extensive blood supply, this often looks more like a significant bump than just relatively flat-appearing swelling. When an injury happens, the body sends cells and a whole cascade of defense mechanisms to the area to aid healing. When the injury heals, this swelling has to go somewhere.

This swelling has a point. When it comes to an ankle injury like a sprain or fracture, the swelling reduces mobility and this is the body’s natural response to protect the joint from further injury. Before modern medicine, if something was injured, we didn’t need a doctor to tell us to stop using it until it heals. The body did that for us. The swelling is part of our hard-wired mechanism inherent to survival.

As the body heals, where does this swelling and hematoma go? Yep, down. Pulled by gravity. If you have a bump on your head, particularly on the forehead, I would cancel any family photos in the next few days to weeks. That blood and extra fluid has to go somewhere and it’s going to settle over your eyes, nose, and cheeks. You will likely be black and blue and often look much worse than you did when you came to the ER in the first place. Your upper eyelids may swell shut.

That doesn’t mean there is something new going on. It doesn’t mean you need to go back to the ER. Blood and body fluids take time to resolve and while that’s happening, they will disperse downwards. Trauma to the nose with or without fractures often settles under the eyes, aka, raccoon eyes. It gets there because at some point most patients lie on their back and under the eyes is lower than the nose in that position.

If you just had knee or hip surgery, particularly big surgeries like joint replacement, your leg will swell. This varies in patients from minor to severe, but it’s not uncommon that weeks after surgery, you will still have more swelling in that leg. Patients are often less mobile post-op so they are not squeezing the muscles as much. That leg often ends up down for a significant portion of time as physical therapy and activities increase. It’s a balancing act: movement and mobility is good but keeping it elevated also helps.

An ankle injury with a lot of swelling might cause the entire foot to turn black and blue and swell as it heals. This is normal, not cause for alarm.

I have had my share of surgeries… knees, shoulders, and a broken clavicle. In every case, the swelling and bruising ended up lower than the area operated on and would appear to be something worth worrying about. Fortunately, I’m aware that gravity works inside as well as outside the body so I didn’t go to the ER.

And like the old adage, time heals all.