If you have ever spent time in a hospital, especially after surgery or during an illness that kept you in bed, you may have had strange-looking sleeves wrapped around your legs.

Every few seconds, they inflate.

Then they relax.

Then they start squeezing again.

And just when you finally get comfortable, a nurse comes in and discovers you’ve taken them off.

There is a reason we keep putting them back on.

These devices are called Sequential Compression Devices, or SCDs, and although they may seem like a small part of your hospital care, they are doing an important job: helping prevent blood clots while you aren’t moving as much as you normally would.

Why Being in the Hospital Changes Your Risk

Movement helps keep blood circulating through your legs.

When you walk, the muscles in your calves contract and help push blood through the veins and back toward your heart. You don’t have to think about it. Your body simply does it as you move throughout your day.

But hospitalization changes that.

You may be recovering from surgery, weak from illness, experiencing pain, connected to equipment, or simply spending far more time in bed than you normally would.

When the legs aren’t moving regularly, blood flow can slow.

That can contribute to the formation of a blood clot in a deep vein, usually in the leg. This is called a deep vein thrombosis, or DVT.

If part of a clot breaks away and travels to the lungs, it can cause a pulmonary embolism (PE), which can be life-threatening.

Preventing these clots is why hospitals pay so much attention to keeping your blood moving.

What Exactly Is an SCD?

An SCD usually consists of soft sleeves wrapped around your lower legs and connected by tubing to a small machine.

The machine fills different areas of the sleeves with air in sequence, creating gentle pressure around the legs.

Then the pressure releases.

The cycle repeats automatically.

That squeezing action helps move blood through the veins and back toward the heart, somewhat mimicking what happens naturally when your leg muscles contract during walking.

They aren’t treating a blood clot.

They’re helping prevent one from forming.

Why Does the Nurse Keep Putting Them Back On?

Because SCDs only help while you’re actually wearing them.

Patients understandably take them off.

They’re hot. They can be uncomfortable. The tubing gets tangled in the blankets. They inflate when you’re trying to sleep. And after hours in a hospital bed, sometimes you simply want one less thing attached to you.

But if your healthcare team has ordered SCDs because you’re at risk for blood clots, long stretches without wearing them reduce the amount of protection they can provide.

That’s why your nurse may keep asking about them or putting them back on after you’ve returned to bed.

It’s not about being difficult.

It’s about prevention.

What Happens When I Get Up?

SCDs are generally used while you’re resting in bed or sitting for extended periods.

When it’s time to walk, the sleeves need to be disconnected or removed so you can move safely.

Don’t try to walk away from the machine while you’re still attached.

Ask your nurse or another member of the healthcare team for help, particularly if you’ve recently had surgery, are weak, are receiving medications that can make you dizzy, or have been told you’re at risk for falling.

And here’s the good part:

Walking itself helps circulation.

The SCD is helping while you’re inactive. Your muscles take over some of that work when you’re safely up and moving.

SCDs Are Only One Part of Prevention

Depending on your individual risk, your healthcare team may use several approaches to prevent blood clots.

You might receive blood-thinning medication. You may be encouraged to perform ankle and leg exercises in bed. Physical therapy may help you begin walking. And your nurses may encourage you to sit in a chair rather than remain in bed all day.

Not every patient needs every intervention.

Your medical condition, surgery, mobility, bleeding risk, and other factors help determine what’s appropriate for you.

When Something Doesn’t Feel Right

SCDs should feel snug as they inflate, but they shouldn’t simply be ignored if something feels wrong.

Tell your nurse if the sleeves are causing significant pain, irritating your skin, seem unusually tight, or if you notice a new problem with your leg.

And don’t assume that new leg pain or swelling is just from lying in bed.

Your healthcare team would rather know about a change and evaluate it than have you stay quiet because you don’t want to bother anyone.

A Nurse’s Perspective

After years of working in hospitals, I can tell you that SCDs are probably not going to be anyone’s favorite part of a hospital stay.

I’ve watched patients pull them off, push them down, disconnect them, and become thoroughly annoyed when we put them right back on.

I understood.

When you’re sick, tired, uncomfortable, and surrounded by equipment, those constantly inflating sleeves can feel like one more irritation.

But there is another side to them that patients don’t always see.

Much of good hospital care isn’t about responding to something that has already gone wrong.

It’s about quietly trying to keep it from going wrong in the first place.

SCDs are one of those quiet preventive measures.

So the next time your nurse walks into the room, looks at your legs, and says, “Where did your SCDs go?”

Now you’ll know why.

Those annoying little sleeves are doing more important work than they appear to be.