Sequential compression devices (SCDs) are specialized medical tools that assist in maintaining healthy blood circulation throughout the body, particularly when a person has limited mobility. This includes situations like hospital stays, recovery immediately following surgery, or prolonged bed rest due to injury. SCDs mechanically mimic the natural pumping action of leg muscles that occurs during movement. This external support helps propel blood back toward the heart, preventing it from pooling in the lower extremities.
What They Are and Why They Are Used
A sequential compression device is composed of two main parts: a pneumatic pump and inflatable sleeves or garments that wrap around the patient’s limbs, typically the legs. The garments contain multiple air chambers connected to the pump, which precisely controls the timing and amount of air pressure delivered. This system is employed primarily to mitigate the risk of Deep Vein Thrombosis (DVT), which involves the formation of a blood clot, most often in the legs.
Immobility is a significant risk factor for DVT because the lack of muscle movement causes blood flow to slow, a condition known as venous stasis. When blood pools, it increases the likelihood of red blood cells and platelets aggregating to form a clot. SCDs address this issue directly by acting as a form of non-pharmacological prophylaxis, or preventative treatment, for patients who cannot move adequately on their own. By mechanically promoting blood flow, the devices reduce the opportunity for stasis and clot formation, thereby protecting against complications like a pulmonary embolism.
How Sequential Compression Works
The functional design of sequential compression relies on a carefully timed and pressurized movement of air through the garment’s chambers. The device creates a “milking” action on the deep veins by inflating the chambers in a specific order, starting at the distal point of the limb, such as the ankle or foot. The pressure then moves proximally, or upward toward the knee and thigh, effectively pushing stagnant blood out of the lower veins and back toward the central circulation.
This systematic compression increases the peak velocity of blood flow in the femoral vein, the large vessel in the thigh, which helps clear the pooled blood. The compression cycle is intermittent, meaning the sleeve inflates for a short period and then fully deflates for a longer rest period before the cycle repeats. This specific timing and gradient of pressure—higher pressure at the ankle than at the thigh—is designed to imitate the body’s natural muscle contractions during movement. By increasing the speed of blood flow, the device prevents stasis and minimizes the chance of platelets adhering to the vein walls.
Patient Guide to Wearing and Caring for SCDs
Proper application and consistent use are important for the effectiveness of a sequential compression device. The sleeves must be fitted snugly around the limb, but not so tight that they cause discomfort or restrict normal circulation when deflated. Healthcare providers will ensure there are no wrinkles beneath the sleeve, as creases can cause skin irritation or pressure points during inflation.
Compliance with the wearing schedule is paramount, as the preventative effect is reduced if the devices are removed for extended periods. To be consistently effective, the sleeves should be worn for the majority of the day, with experts suggesting at least 18 to 20 hours daily while the patient is immobile. The pump will automatically cycle, but patients should alert a caregiver if the device’s alarm sounds, which usually indicates an issue like a disconnected tube or a kink in the hose.
During use, skin care underneath the sleeves is important to prevent breakdown or irritation. Patients should immediately report any sensation of pain, numbness, tingling, or excessive warmth beneath the garment to their healthcare team. The sleeves themselves are typically disposable or washable, and while they are in use, they should be kept clean and dry to maintain skin integrity.