Esophageal Impedance

What is esophageal impedance?

Esophageal impedance is a diagnostic test that measures gas or liquid in the esophagus, the tube through which food travels from the throat to the stomach. Doctors use this test to determine if a child has gastroesophageal reflux disease (GERD), a chronic disorder that happens when acid, food or fluid flows backward from the stomach into the esophagus.

In this test, a thin, flexible tube is passed through the child's nose, down the back of the throat and into the esophagus. The end of the tube is attached to a computer that remains at the child's bedside throughout the study.

An impedance study typically takes 18 to 24 hours. The tube is left in place during this time and a parent or guardian usually stays with the child in the hospital room.

How should I prepare my child for an esophageal impedance study?

Your child must have an empty stomach for an impedance study.

  • children younger than 6 months must have NOTHING to eat or drink for two hours before the impedance study
  • children older than 6 months must have NOTHING to eat or drink for four hours before the impedance study

Some medications interfere with the impedance study. If your child takes any medication, speak with your child’s doctor a week before the test about altering the medication schedule.

What happens during an esophageal impedance study?

Your child will need to stay at the hospital overnight for this procedure. They will need to stay in the room close to their bed and use a bedside toilet instead of walking to the bathroom.

After a nurse checks your child's height to determine where to place the tube, the procedure involves the following steps:

  • Your child will dip their finger into a special liquid to help calibrate the computer.
  • The nurse will pass a tube through your child's nose into the stomach. You may stay with your child while the tube is put in place.
  • Infants and young children will be snuggled in a blanket to help them to feel secure and stay still while the tube is being passed.
  • Older children, who are more likely to cooperate, may prefer to sit in a chair while the nurse passes the tube.
  • At first the tube may cause your child to cough, sneeze or gag. Once the tube is in place, the discomfort should pass.
  • The tube will be taped into place on your child's cheek. Your child will have an X-ray to check the exact position of the tube. Depending on the X-ray results, the tube may have to be repositioned and re-taped.
  • Special sleeves may be put on infants and small children to prevent them from bending their elbows and pulling out the tube.
  • You will be asked to write down what your child is doing while the tube is in place, such as eating, sleeping or coughing. Your child's nurse will explain exactly what needs to be written down to help with the study.
  • A clinician will remove the tube the next day. Removing the tube takes less than a minute and does not hurt.

After the procedure, a doctor will interpret the information recorded in the computer and compare it to the child’s activities you recorded during the test. The results should be ready in one week.