Efficient atraumatic liquid suction by means of slit suction tubes combined with a pressure control unit.

In 1976 a modified suction system for neurosurgery and precision surgery was presented. It was developed to meet the need for efficient and atraumatic liquid suction. the system consists of suction tube ends provided with three vertical slits in the suction edge (W-tubes), a Pressure Control Unit (PCU) and an independent suction pump with an air capacity of 25-30 litres per min. This system has subsequently been modified for microsurgery. The PCU normally controls the negative pressure to 20 kPa (corresponding to 200 cm of water) for atraumatic suction of liquid, which is needed during most of the operating time. For suction of various tissues or cleaning the system, the surgeon can set the pressure limit to 50 or 90 kPa by means of a foot-operated IR-transmitter in a pedal with a kick-down function. The PCU and the W-tubes, which neutralize the pressure load on tissue and the sudden interruption of liquid flow that are inevitable with conventional suction tips, form a system with a high liquid suction capacity in spite of the atraumatic suction pressure. This is possible because the slits maintain a large active suction area. Crushed or soft tissues and coagulated blood are aspirated as and when required, if necessary by elevation of the negative pressure limit. The W-tubes are not provided with an air inlet hole on the tube because that method of pressure control proved unpredictable and variable and reduced the suction capacity by interfering with the flow.(ABSTRACT TRUNCATED AT 250 WORDS)