A catheter body (210) defines a distal-most suction orifice (444) and an outer lateral wall (592), which defines a lateral opening (448) therethrough into a suction lumen (530). An inflatable-element outer wall (590) of an inflatable element (588) is mounted to the catheter body (210). An inner membrane (589) is positioned within the inflatable element (588) and is mounted to the catheter body (210) around the lateral opening (448) along a seal perimeter (583) around the lateral opening (448), so as to define a collapsible membrane portion (596) that (a) covers the lateral opening (448), and (b) together with the inflatable-element outer wall (590), defines an inflatable chamber (587) between the inflatable-element outer wall (590) and the collapsible membrane portion (596). The inner membrane (589) entirely surrounds the catheter body (210).
