An insertion device for inserting a cannula through tissue generally comprises an inner shaft, a tip member coupled to a distal end portion of the inner shaft, a hollow outer shaft slidably received over the inner shaft, and a compressible member received over the inner shaft between the tip member and the outer shaft. The compressible member is configured to be received in a lumen of the cannula, and the inner shaft is movable relative to the outer shaft along an axial direction to compress the compressible member between the tip member and the outer shaft so that the compressible member expands in a generally radially outward direction. The radial expansion of the compressible member releasably secures the insertion device to the cannula.
