A multistage balloon catheter that uses a single lumen to inflate a balloon in stages is disclosed. A fluid port provides fluid communication from an inflation lumen in the balloon catheter to the inner volume of a distal balloon. The distal balloon expands as fluid in delivered to the inner volume of the distal balloon. Once inflated, the pressure continues to rise until a threshold pressure is exceeded. A pressure sensitive inflation valve provides fluid communication into an inner volume of a second balloon disposed at least partially proximal to the distal balloon. The pressure sensitive valve allows fluid communication into the second balloon once the threshold pressure is reached in the first balloon thereby inflating the second balloon.
