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 hygiene , suction is used to remove fluids from the airways,  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 . 
Suction devices may be mechanical hand pumps or battery or electrically operated mechanisms. The plastic, rigid Yankauer suction tip is one type of tip attached to a suction unit. Another is the plastic, nonrigid French or whistle tip catheter.