Compression stockings
Compression stockings are elastic garments worn on the legs or feet that apply graduated pressure, typically strongest at the ankle and decreasing upward, to improve blood flow and prevent venous pooling.[1] They work by squeezing the legs to facilitate the upward movement of blood toward the heart, thereby reducing swelling and, to a lesser degree, the risk of blood clots.[2] These stockings are a form of compression therapy commonly prescribed for conditions involving poor circulation in the lower extremities, including chronic venous insufficiency, varicose veins, lymphedema, and edema.[3] They are also used prophylactically to prevent deep vein thrombosis (DVT), particularly in high-risk situations such as prolonged immobility, post-surgery recovery, or long-distance travel.[4] Evidence from randomized controlled trials supports their efficacy in accelerating the healing of venous leg ulcers. For postthrombotic syndrome, evidence for prevention is limited and mixed, with some benefit observed in symptom management when applied consistently.[1][5] Available in various types, compression stockings are classified by pressure levels—mild (15-20 mmHg) for everyday support, moderate (20-30 mmHg) for symptomatic relief, and firm (30-40 mmHg or higher) for medical conditions—ensuring they are fitted precisely to the individual for optimal effectiveness.[6] While generally safe, potential side effects include skin irritation or discomfort if improperly fitted, underscoring the importance of professional guidance for selection and use.[7]Overview
Definition and purpose
Compression stockings are tight-fitting elastic garments that apply graduated external pressure to the legs, with the greatest compression at the ankle tapering upward toward the calf or thigh.[8][7] This design promotes the upward movement of blood through the veins, enhancing overall circulation.[9] The primary purposes of compression stockings include improving venous return to the heart, preventing blood from pooling in the lower extremities, and reducing leg swelling.[1] They also help alleviate discomfort from circulatory challenges and support recovery by facilitating better blood flow.[10] These stockings are typically constructed from elastic blends such as spandex (elastane), nylon (polyamide), or cotton, which enable the necessary stretch and pressure exertion.[11] They come in open-toe or closed-toe options to suit different foot conditions and user preferences.[12] In contrast to ordinary socks, which provide minimal or no therapeutic compression, compression stockings deliver calibrated pressure measured in millimeters of mercury (mmHg) for medical benefit.[7][13]Mechanism of action
Graduated compression stockings apply the highest pressure at the ankle, typically ranging from 20 to 30 mmHg, with pressure decreasing proximally toward the thigh or knee to facilitate upward blood flow against gravity.[14] This gradient mimics the natural hydrostatic pressure gradient in the lower extremities, promoting venous return to the heart while minimizing stagnation in dependent areas.[1] The primary effects on veins involve reducing venous diameter, which enhances valve coaptation and function, thereby countering hydrostatic pressure to prevent reflux and blood pooling.[1] By narrowing the vein lumen, compression increases linear blood flow velocity and reduces venous volume, as demonstrated by color Doppler ultrasound studies showing significant decreases in popliteal vein diameter and increases in femoral vein peak velocity with thigh-length stockings.[15] These changes help reverse ambulatory venous hypertension without substantially impeding arterial inflow.[1] Compression also impacts muscle and lymphatic systems by augmenting the calf muscle pump mechanism during ambulation, which further propels blood upward through the veins.[1] This augmentation improves overall venous return and enhances lymphatic drainage by compressing tissues to reduce interstitial fluid accumulation and edema.[1] Hemodynamically, these effects result in higher venous velocity, lower venous capacitance, and stabilized peripheral circulation, contributing to better limb oxygenation as evidenced by near-infrared spectroscopy.[1] Doppler ultrasound evidence further supports improved venous ejection fraction and reduced residual volume fraction, indicating enhanced pumping efficiency in the lower limbs.[16][15]Types and classification
Compression levels
Compression stockings are classified by the level of pressure they apply to the lower extremities, measured in millimeters of mercury (mmHg), which indicates the intensity of compression provided. This classification ensures standardized therapeutic effects, with higher levels delivering stronger pressure to address more severe circulatory issues. The system typically divides stockings into four main classes based on the pressure exerted at the ankle, as this is the reference point for measurement.[17] In Europe, the RAL-GZ 387 quality assurance standard governs manufacturing consistency for medical compression hosiery, specifying pressure ranges for each class to ensure precise therapeutic delivery across products. The following table outlines the RAL-GZ 387 compression classes, their pressure ranges, and general therapeutic indications (note: ranges may vary slightly by region, e.g., broader in US classifications like 15-20 mmHg for mild support):| Class | Pressure Range (mmHg) | Indication |
|---|---|---|
| 1 | 18–21 | Mild support for minor swelling or fatigue |
| 2 | 23–32 | Moderate venous insufficiency or varicosities |
| 3 | 34–46 | Severe venous disorders or post-thrombotic syndrome |
| 4 | >49 | Extreme edema or lymphedema management |