A multi-lumen catheter with a connectable hub for monitoring intra-abdominal pressure including an expandable outer balloon and a first lumen communicating with the balloon. The balloon and first lumen are filled with gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A second lumen communicates with the bladder to remove fluid from the bladder. The hub includes a pressure transducer for measuring bladder pressure based on gas compression and has an elongated member insertable into the first lumen to advance gas through first lumen to expand the balloon.
