Before you go in for esophageal manometry, you may be asked to fast for a set period, or to drink only clear liquids. You might also need to avoid taking certain medications. Before the procedure, your doctor puts pain-relieving medication in your nose to make you more comfortable. Then, a thin, flexible tube (catheter) is inserted through your nose, down your esophagus and into your stomach. The end of the tube sticking out of your nose is connected to a machine that measures the functions of your esophagus. After the tube is in place, your doctor will ask you to swallow bits of water to measure how your esophagus is working.