Fluoroscopy - Sniff Test

What is a Sniff Test?

A sniff test is the fluoroscopic evaluation of the diaphragm, the muscle between the chest and abdomen that raise and lower as you breathe in and out.

What are some common uses of the procedure?

A sniff test is performed for patients who have shortness of breath or dyspnea (difficulty breathing).  Many patients have had trauma that may have caused one or both of the diaphragms to become paralyzed.

How should I prepare for the procedure?

No special preparation is necessary before a sniff test.  Food and fluid intake do not need to be restricted.

Before the procedure begins, you will be asked to remove all jewelry and to change into a gown, so that no metal items will show up on the images.

Women should always inform their physician or technologist if there is any possibility that they may be pregnant.

What does the equipment look like?

You will be positioned standing behind a box like structure that contains the x-ray tube and fluoroscopic equipment that will send the images to a screen in the exam room.

How does the procedure work?

A radiologist monitors the movement of the diaphragms with the use of a fluoroscope, a device that projects radiographic images in real time onto a screen in the exam room.

How is the procedure performed?

You will be positioned, standing, in front of the fluoroscopic equipment.  The radiologist will have you breathe in and out as he/she monitors the movement of the diaphragms.  You will be asked to "sniff" in quickly several times.  Still images may be taken of each diaphragm.  The exam is usually completed within 5 minutes.

What will I experience during the procedure?

There is no discomfort associated with this procedure, unless you are already experiencing painful respiration.  It is similar to having a plain chest x-ray.

Who interprets the results and how do I get them?

A radiologist will interpret the images, and a signed report will be sent to your physician who will discuss the results with you.