About Your Zephyr pH Monitoring System

This information will help prepare you for the Zephyr pH Monitoring System at Memorial Sloan Kettering (MSK).

The Zephyr pH Monitoring System measures reflux. It is a useful test for people who regurgitate food and liquids that are not acidic, people who are still having reflux while taking medications, and people who have reflux after meals.

Before Your Procedure

Most people will receive anesthesia (medication to make you sleepy) for this procedure. If you are not going to receive anesthesia for this procedure, your doctor will tell you.


If you take insulin or other medication for diabetes, you may need to change the dose on the day of your procedure. Ask the doctor who prescribes this medication for you what you should do the day before and the morning of your procedure.

Medical devices

If you have an automated implanted cardioverter-defibrillator (AICD), you will need to get a clearance letter from your cardiologist before your procedure.

Arrange for someone to take you home

You must have someone 18 years or older take you home after your procedure. If you don’t have anyone, call one of the agencies below. They will provide someone to accompany you home, however there is a charge for this service and you will need to provide the transportation.


In New York:
     Partners in Care 888-735-8913
     Prime Care 212-944-0244

In New York or New Jersey:
     Caring People 877-227-4649

Back to top

3 Days Before Your Procedure

A few days before your procedure you will receive a telephone call from an endoscopy nurse. He or she will review the instructions in this guide with you and ask you questions about your medical history. The nurse will also review your medications and tell you which to take the morning of your procedure. Use the space below to write them down.

Back to top

The Day Before Your Procedure

Time of your procedure

A clerk from the Admitting Office will call you after 11:00 am the day before your procedure. He or she will tell you what time you should arrive at the hospital for your procedure. If you are scheduled for your procedure on a Monday, you will be called on the Friday before. If you do not receive a call, please call 212-639-7882.

If you need to cancel your procedure for any reason, please call the doctor who scheduled it for you.

Back to top

The Evening Before Your Procedure

Instructions for eating and drinking before your procedure

12 ounces of water

  • Do not eat anything after midnight the night before your procedure. This includes hard candy and gum.
  • Between midnight and up until 2 hours before your scheduled arrival time, you may drink a total of 12 ounces of water (see figure).
  • Starting 2 hours before your scheduled arrival time, do not eat or drink anything. This includes water.
Back to top

The Day of Your Procedure

Things to remember

  • Take the medications you were instructed to take the morning of your procedure with a few sips of water.
  • Do not put on any lotion, cream, powder, deodorant, makeup, or perfume.
  • Remove all jewelry, including jewelry in body piercings.
  • Leave all valuables, such as credit cards and jewelry, at home.
  • If you usually wear contact lenses, wear your glasses instead.

What to bring with you

  • A list of the medications you take at home
  • Your rescue inhaler (such as albuterol for asthma), if you have one
  • Only the money you may need
  • A case for your glasses
  • Your Health Care Proxy form, if you have completed one

Where to park

Parking at Memorial Sloan Kettering is available in the garage on East 66th Street between York and First Avenues. To reach the garage, enter East 66th Street from York Avenue. The garage is located about a quarter of a block in from York Avenue, on the right-hand (north) side of the street. There is a tunnel that goes from the garage into the hospital. For questions about prices, call 212-639-2338. There are also commercial garages nearby, on East 69th Street between First and Second Avenues and on East 65th Street between First and Second Avenues.

Where to go

Your procedure will take place in the Endoscopy Suite at the main hospital, which is located at 1275 York Avenue. Take the M elevator to the 2nd floor.

What to expect

Once you arrive at the hospital, doctors, nurses, and other staff members will ask you to state and spell your name and date of birth many times. This is for your safety. Patients with the same or similar names may be having procedures on the same day.

After changing into a hospital gown, you will meet your nurse. If you are going to receive anesthesia, your nurse will place an intravenous (IV) catheter into a vein, usually in your hand or arm. At first, you will receive fluids through the IV, but it will be used later to give you the anesthesia. Your nurse will also check your heart rate, breathing, and blood pressure.

Your doctor will explain the procedure to you and answer any questions you have. He or she will ask you to sign a consent form.

When it’s time for your procedure, you will be brought into the procedure room and helped onto an exam table. If you are receiving anesthesia, it will be given through your IV after you are attached to equipment to monitor your heart rate, breathing, and blood pressure. You will also receive oxygen through your nose. Your doctor will insert a probe through your nose and into your stomach. It will be taped to your nose and attached by a wire to a recorder that you will wear on your waist. The probe will measure both the acidic and nonacidic reflux events you have. The probe will record these events over a 24-hour period.

Back to top

After Your Procedure

In the recovery room

If you have had anesthesia, you will wake up in the recovery room. Your nurse will continue to monitor your heart rate, breathing, and blood pressure. Once you are fully awake, your nurse will remove your IV. If you have someone waiting with you, your nurse will explain your discharge instructions to both of you before you go home.

At home

You should not have any pain after your procedure, but you may still feel sleepy if you had anesthesia.

You will be given a diary the day of your procedure. It is important that you keep accurate records in this diary. This will help the doctor decide how best to help you. Be sure to write down the following:

  • All reflux symptoms you have, such as coughing, heartburn, burping food into your mouth (regurgitation)
  • All medication you take
  • Everything you eat and drink
  • The time you eat and drink

You will also have a recorder. Use the buttons to record your body position by using the upright button when you are upright and the down button when you are lying down. Record any symptoms you experience by pressing the symptom button on the monitor, and write the symptoms in your diary.

While the probe is in place, follow these important directions

  • Do not take a shower or bath. The recorder and probe must not get wet.
  • Avoid foods high in acid, such as coffee, orange juice, cranberry juice, and soda, as well as gum and throat lozenges. These foods will affect the test results.
  • Continue your normal activities, including working, exercising, and eating. Try to do activities that will bring on your symptoms.
  • Sleep as flat as possible. It does not matter if you sleep on your side or back.
  • Keep the recorder on your body at all times. You can put it under your pillow when you sleep.
  • You may or may not be off your acid-suppressant medications for this test. Your doctor will decide this.


You will be given an appointment with the doctor who performed your procedure 24 hours after the procedure. During this appointment your nurse will remove the probe, and you will return the receiver and your diary.

Back to top

Call your doctor if you have

  • A temperature of 101° F (38.3° C) or higher
  • Severe or constant stomach pain, hardness, or bloating
  • Severe or constant pain in your chest
  • Difficulty swallowing
  • Nausea or vomiting (including stomach contents or blood)
  • Severe or constant bleeding from your nose
  • Any unexplained or unexpected problems
Back to top

Last Updated