A peak flow meter is a portable instrument that analyzes how efficiently air exits your lungs. During an asthma attack, your airways often constrict. A peak flow meter can measure this narrowing hours, even days, before you have any asthma symptoms.

A peak flow meter is so sensitive to changes in your airways that it can detect breathing problems much better than a doctor can using a stethoscope to listen to your lungs.

You may be able to avoid a major asthma attack by taking your asthma medication when your peak flow meter suggests changes — before you detect symptoms.

What Are the Peak Flow Zones?

Once you've determined your personal greatest peak flow number, your doctor will provide you with a range of values that will tell you what to do next. The peak flow data are shown on a chart with zones labeled with colors. It is preferable if these target zones are included in your Asthma Action Plan. This will assist you in determining what to do if your peak flow number changes. As an example:

  • The Green Zone (80 to 100 percent of your personal best figure) indicates that everything is well. There are no signs of asthma.
  • Yellow Zone (50 to 80 percent of your personal best number) signals caution. You should take a pain reliever and monitor your peak flow to determine whether it returns to the green zone.
  • Red Zone (below 50 percent of your personal best number) signals a medical emergency. You must take your pain reliever as soon as possible.

How does the procedure work?

X-rays, like light and radio waves, are a type of radiation.The equipment emits a brief blast of radiation that travels through your body. The radiation creates a picture, which is then recorded on photographic film or a specific detector.

The x-rays are absorbed to differing degrees by different areas of the body. Dense bone absorbs most of the radiation, while soft tissue (muscle, fat, and organs) allows more x-rays to flow through. As a result, bones look white on x-rays, soft tissue appears grey, and air appears black.

The ribs and spine absorb a lot of radiation and look white or light grey on a chest x-ray. Because lung tissue absorbs less radiation, it appears dark on the image.

The majority of x-ray images are digital files that are electronically stored. Your doctor will have easy access to these saved images in order to diagnose and manage your condition.

What are the advantages?

  • No radiation stays in your body after an x-ray exam.
  • X-rays usually have no side effects in the typical diagnostic range for this exam.
  • X-ray equipment is relatively inexpensive and widely available in emergency rooms, doctors’ offices, ambulatory care centers, nursing homes, and other locations. This makes it convenient for both patients and doctors.
  • Because x-ray imaging is fast and easy, it is very beneficial for emergency diagnosis and treatment.