The invention provides a nested tubing cannula which comprises outer and inner
elongate tubular members, both having a proximal end, a distal end, and a lumen
therebetween. The inner tubular member is sealed at its distal end and is nested
substantially coaxially within the lumen of the outer tubular member, so that the
gap between the inner and the outer tubular member defines a second lumen whereas
the first lumen is the lumen of the inner tubular member. A tubular sleeve is disposed
coaxially between the inner and outer tubular members. A balloon is mounted on
a distal region of the outer tubular member and is in communication with the first
lumen. The cannula further comprises a port proximal or distal the balloon occluder
and is in communication with the second lumen. Methods for making the devices herein
are disclosed.