LSU Aspirator

The portable LSU model suction unit. Typically, used on an ambulance.

Suction is the flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Suction is popularly thought of as an attractive effect, which is incorrect since vacuums do not innately attract matter. Dust being "sucked" into a vacuum cleaner is actually being pushed in by the higher pressure air on the outside of the cleaner.

The higher pressure of the surrounding fluid can push matter into a vacuum but a vacuum cannot attract matter.

In medicine, devices are sometimes necessary to create suction. Suction may be used to clear the airway of blood, saliva, vomit, or other secretions so that a patient may breathe. Suctioning can prevent pulmonary aspiration, which can lead to lung infections. In pulmonary toilet, suction is used to remove fluids from the airways,[1] to facilitate breathing and prevent growth of microorganisms.

In surgery, suction can be used to remove blood from the area being operated on to allow surgeons to view and work on the area. Suction may also be used to remove blood that has built up within the skull after an intracranial hemorrhage.[2]

Suction devices may be mechanical hand pumps or battery or electrically operated mechanisms. The yankauer suction tip is one type of tip attached to a suction unit. Another is the Frazier suction tip.


  1. Allen GS, Coates NE |title=Pulmonary contusion: A collective review |journal=The American Surgeon |volume=62 |issue=11 |pages=895–900 |year=1996
  2. Valadka AB |chapter=Injury to the cranium | editor = Moore EJ, Feliciano DV, Mattox KL publisher=McGraw-Hill, Medical Pub. Division |location=New York |year=2004 |pages= 385–406 |isbn=0-07-137069-2 | accessdate= 2008-08-15