Structure and Working Principle of Negative Pressure Drainage Bags

Negative pressure drainage bag—also known as a negative-pressure drainage bulb or a disposable negative-pressure drainage device—is a Class II sterile, disposable medical consumable. It is a closed drainage system that generates internal negative-pressure suction through the manual squeezing of the bulb to actively evacuate blood, exudate, and pus from a wound, distinguishing it from standard drainage bags that rely on gravity flow.

 

- Flexible negative-pressure fluid reservoir (transparent and squeezable).
- Connecting drainage tube.
- One-way anti-reflux valve (prevents fluid from flowing back into the wound).
- Graduated fluid reservoir bag/bulb.
- Drainage port.

 

1. Squeeze the bulb to expel air and close the drainage valve, creating negative pressure inside.
2. The negative pressure continuously draws exudate from the surgical wound or body cavity through the tubing.
3. Fluid flows into the sealed bulb without backflow or leakage.
4. Once full, open the valve to drain the fluid, then squeeze the bulb again to re-establish negative pressure for continued use (for single-patient use only; do not reuse across different patients).

 

- Standard drainage bags: Rely on gravity for flow; blood tends to pool when the patient is lying down, and backflow is likely.
- Negative-pressure drainage bags: Actively suction fluid out; drainage continues even when lying flat, and they prevent backflow, thereby reducing the risk of hematoma and infection.