Valve mechanism

Abstract

A valve mechanism () for attaching to a proximal end () of a trocar cannula () for minimising leakage of insufflating and other gases proximally from the trocar cannula (), comprises a housing () adapted for securing to the trocar cannula () adjacent the proximal end () thereof. The housing () defines an instrument bore () extending from a proximal end () to a distal end (). A distal valve () is located adjacent the distal end () of the instrument bore () and is pivotal from an open state to a closed state. A proximal valve () is located towards the proximal end () of the instrument bore (), and comprises first and second valve members () and () which are urgeable from a withdrawn state clear of the instrument bore () to an engagement state sealably engaging an instrument in the instrument bore () for sealing the instrument bore (). A detecting probe () pivotal about a primary pivot axis () is urgeable distally from a first state to a second state by the distal end of an instrument passing distally through the instrument bore (). A drive transmission () transmits drive from the detecting probe () to the proximal and distal valves (), so that as the detecting probe () is urged from a first state to a second state the distal valve () is urged into the open state and the proximal valve () is simultaneously urged from the withdrawn state to the engagement state to minimise leakage of gas proximally through the instrument bore () and to minimise contact of an instrument with the proximal and distal valves ().