Filter assembly for connecting intermediate an epidural cannula and a syringe

An epidural filter for connecting intermediate a syringe and an epidural cannula has a two-part housing formed with an inlet and an outlet. Within the housing a filter membrane is supported, parallel with the direction of fluid flow through the filter, by struts located on opposite sides of the membrane. Fluid is supplied to the filter from the syringe via a female Luer-tapered bore and distributed over the filter membrane along a channel and passages between the struts. The filter has an outlet coupling comprising a nose, having a bore, around which extends a screw-threaded collar. A clamping head is screwed into the collar about the nose so that the nose bears on a resilient bush contained within the head. The bush has a bore which receives the cannula so that when the clamping head is screwed onto the housing it forms a fluid-tight seal between the cannula and the housing.