Surgical drains are implants that allow the removal of fluid and/or gas from a wound or body cavity. This broad definition includes nasogastric tubes, urinary catheters, vascular access ports, and ventriculoperitoneal shunts.
Surgical drains can help the healing process by removing inflammatory mediators, bacteria, foreign material, and necrotic tissue. Different types of surgical drains include:
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Active drains are closed systems that collect fluid into a reservoir. This reservoir prevents saturation of bandage material, decreases the risk for ascending infection, and can limit exposure of hospital staff or other patients to contaminated fluid. Active drains apply an artificial pressure gradient to pull fluid or gas from a wound or body cavity.
Negative pressure increases the efficiency of active over passive drains, enables placement of the drain exit in any position, can remove fluid against gravity if necessary, and can be used to collapse dead space.
Passive drains are made of latex, polypropylene, or silastic rubber. These drains are most commonly used in wounds, after surgery where dead space is present, or when an accumulation of fluid is anticipated. They work by capillary action, gravity, overflow, or fluctuations of pressure gradients caused by body movement.
Regardless of the type of surgical drain used, proper placement is crucial for optimal function. Because any air that enters the system will affect the negative-pressure gradient, care must be taken to ensure that the system is closed.