What does it mean???
Peak-Flow Meters Cheap and Easy for COPD Detection
Different Peak Flow Meters out there and they all do the same thing, measure how fast you can move air out of your lungs.
THE PEAK FLOW METER
Regular peak flow monitoring will help you to understand and manage
your asthma better.
It is not unusual for people with asthma to feel fine and not notice changes in their breathing,
even when the airways may have become significantly narrower.
Know the zones!
Red zone: medical alert
Yellow zone: caution
Green zone: all clear
.....PEAK FLOW METER - A THERMOMETER FOR ASTHMA.....
A peak flow meter is a small portable device with a measuring gauge.
It measures the force and speed that air is blown out of the lungs. This
measurement is referred to as the peak expiratory flow rate (PEFR). A peak
flow meter is a
Although peak flow monitoring can be done by anyone
over age five, it may not
WHAT DOES IT ALL MEAN?
Peak flow monitoring is done to detect changes in airways, to adjust
PRINT OUT YOUR OWN PERSONAL PEAK FLOW CHART
The Peak Flow Meter
Peak Flow Meter is an important device to help control your asthma! The Peak Flow Meter is used to determine your Peak Expiratory Flow Rate or PEFR. Your PEFR provides a simple, objective, and repeatable way of tracking the severity of your asthma.
The basic structure of a Peak Flow Meter consists of a tube with a sliding indicator that moves along a scale marked in liters per minute. Generally the numbers marked on the tube range from about 60 to around 800 (Peak Flow Meters with a smaller scale range are used for pediatrics). There will also be a way to select color coded ranges; green, yellow, and red. To use a Peak Flow Meter you simply take as deep a breath as possible, put the peak flow meter in your mouth, and blow as hard and as fast as you can. It is not necessary to exhaled totally, which can cause coughing.
The color coded ranges should be determined while working with your physician and/or respiratory therapist. The green range represents your Personal Best. To establish your Personal Best you'll have to be as symptom free as possible. Some patients may
need to be on oral steroids for a period of time to establish their Personal Best. Begin by recording PEFR results at least twice a day for 2-3 weeks in accordance with your physicians instructions. The best results are usually achieved in the evening after bronchodilator therapy. If your Personal Best is not within 80% of your predicted normal value a change in therapy may be indicated. The Personal Best value should be rechecked annually to account for a child's growth and possible improvement/deterioration of asthma in both children and adults.
Once your Personal Best is found, your Green Zone becomes 80 to 100 percent of this value. As long as your PEFR results stay in this range, you're in the clear. This range indicates that your Asthma Plan, plan drawn up by yourself, your physician, and/or therapist, is working and no asthma symptoms are present. If your PEFR results stay in this range, you should talk to your physician about reducing therapy/medications.
What about the Yellow Zone? Like the yellow traffic light, the Yellow Zone means caution. The Yellow Zone is 50 to 80 percent of your Personal Best. A number of factors could cause Peak Flows to fall. Exposure to Asthma Triggers is often at fault. The Yellow Zone indicates that something is going on and you need to be careful. You may need to increase your treatments or medication for a short time. It could also indicate that your present routine treatment schedule is not enough to keep your asthma in check and needs to be increased. The important thing is, NOW is the time to call your physician and get a jump on symptoms and head off any worsening of your asthma.
Now for the Red Zone. If your PEFR land here, you're below 50 percent of your personal best. Stop whatever you are doing and take your Rescue Medication Inhaler. If your PEFR does not return to the Yellow or Green Zone and stay there, Call Your Physician, IMMEDIATELY! Most deaths from asthma are due to the person waiting too long to seek help.
To wrap this up, keeping records of your PEFR is very important. It helps your physician and therapist spot trends that would be missed otherwise. Keeping notes along with your PEFR results can help determine some of your asthma triggers, wet/dry weather, animal contact, etc. Remember, all of this needs to be developed with your physician and respiratory therapist. Keep their phone numbers close at hand and don't hesitate to contact them.
NOTE: One limitation of Peak Flow Readings is that it only measures the condition of the large airways. If there are problems occurring in the small airways, a person can be symptomatic and still have good peak flow readings. Our Illustrated Tour of the Respiratory System is available as a guide to the many parts of breathing anatomy.
ALL ABOUT PEAK FLOW METERS
A peak flow meter is a great way to keep track of the state of your lungs. Although it is not as "good" a measure as FEV1, it is a measure that can be taken, and tracked, at home. Your "gadget" must have come with an instruction sheet. On that instruction sheet there should be a table, indicating what the "norm" is for healthy people of your age, height, and sex. (Bear in mind that the "normal" range is not absolute: your peak flow can be anywhere from 80% to 120% of the "norm" and still be considered "normal.") Realistic people, however, shoot to beat their own "personal best", or the score they got on their last PFTs. I presume you have a copy of your results. (If you don't -- get them!) On the first set of tests, the airway obstruction tests, you will see the initials PEF (Peak Expiratory Flow). That's the number you should take as your baseline, and see if you can improve on it, or at least not fall below it.
Just blow on your meter, hard as you can! Fill up your lungs, and blow! With practice, you can figure out the best way to blow in order to make the little marker go higher. (No, that is NOT cheating!) And it is good exercise, great for the abdominal muscles.
Then, mark down your BEST score. Your instruction sheet should have a little chart. If it does, make xeroxes of it, because you canfinish the chart off pretty fast, if you test yourself more than once a day. I scribble in little comments at
the top of each column, as well. The reason that I do that is in order to track such things as the following:
1. is my peak flow better at some times of day than others
2. Does exercise improve it? (aerobic yes, weight-lifting no
3. Do bronchodilators improve it? .................................
4. Any other factors improve it or depress it? .................
(Bronchial infections sure depress it -- to a very depressing degree.)
Forced Expiratory Volume (FEVT
The FEVT is the volume of gas expired during a given time interval (T) from the beginning of the FVC maneuver. The FEVT is normally stated in liters (BTPS), and T is expressed in seconds. Of the various FEVT measurements the FEV1 is the most widely used.
Decreased FEVT values are common in both obstructive and restrictive patterns. Distinction between obstructive and restrictive causes of reduced FEVT is made by relating the FEVT to the VC as the FEVT/FVC ratio , and to other flow measurements. In obstructive patterns the FVC may be normal and the FEVT reduced; in restrictive patterns the FVC and the FEVT are proportionally decreased.
The FEV1 and the FEV1/FVC ratio are the most widely used and best standardized indices of obstructive disease and is used for assessment of response to bronchodilators, inhalation challenge studies and for detection of exercise-induced bronchospasm.
I'd like to provide some input to the question asked about the FEV1
I'm a respiratory therapist, working in 2 places. One of the places is a chronic care/rehab hospital. Here I am doing research with COPD, mainly medications (for those southern Ontarians, it is West Park Hospital). The second place is at an acute care hospital.
The letters stands for "Forced expiratory volume in 1 second". Basically this means the volume of air you breathe out in one second, WHEN you breathe out fast. As most of you know, when people with COPD breathes out fast (or forced)
it is much less than the value when breathed out slowly. This is one of the biggest indications that a person has an obstructive lung problem.
When you go to the pulmonary function lab, they calculate a number called a "predicted" value. Basically this is the number that is supposed to be the "optimal" for your age, sex and height. The lab then takes the value YOU breathe (called "actual"), and figures out a percentage. Both the actual number and the percentage are used by practitioners. There are several equations, but all of them yield pretty much the same number. This is one of them:
Females: (0.0342 x height in cm) - (0.0255 x age in years) - 1.578
Males: (0.0414 x height in cm) - (0.0244 x age in years) -2.190
The result is in liters.
To figure out your percentage (called "percent predicted"), take your actual value, divide into the predicted value
(which is yielded by the equation above) and times it by 100. The clinical values are as follows:
Any number above 80% is normal lung function
Between 65% and 80 % is mild impairment
Between 50 % and 65% is moderate impairment
Less than 50% is severe impairment.
Less then 34=Very severe
But we all are different and we all cope differently.
The progression of COPD and what to do about keeping a certain "quality" of life
I would like to relate to all of you what it has been like the last 5 years with end-stage emphysema. In 1994 while reading
a book I started coughing and could not stop and could not catch my breath. Went to a primary care facility and they wanted to send me to the hospital but I refused (scared). I instead went to a Pulmonary doctor at which time he had me take a PFT (Pulmonary function test). The results showed I had FEV1 of 13% of predicted, and also found I had a lung infection. At this time I had been smoking for 43 Years about 3 packs per day. It took about 6 weeks to clear up the infection and had another PFT which showed a FEV1 of 18%, now he put me on all the usual meds except for Prednisone. So using 18% as a starting point this is my progression....
1994 FEV1 18%
1995 FEV1 21% (QUIT SMOKING 2 MONTHS BEFORE PFT TEST)
1996 FEV1 26%
1997 FEV1 27%
1998 FEV1 26% (had one high one of 33% during year)
1999 FEV1 26%
I feel this case history shows a person may halt or slow down the progress of emphysema. Of course the predicted has came down
(4.0 to 3.92) as would happen to a person without emphysema. Other things I have done besides quiting smoking are....
Visit my Pulmonary doctor every 2-3 months. (stick to him like glue)
Do not visit anyone who is sick with a respitory illness.
Have no-one vist me who is sick, my children or my grandkids.
Always wash hands when coming in from the store etc.
Do everything at my pace only.
Do only those things I can or like, file 13 for anything else.
Follow my doctors orders
Motivate my doctor to do a good job in my health
Exercise every day (mostly walking)
Attend intial pulmonary rehab and follow their teaching.
And once more QUIT SMOKING.
Establishing your personal best reading
Although your predicted "normal" peak flow is determined by height, age and gender, it is preferable to gauge asthma control by comparing daily peak flow recordings with your "personal best" reading. This is defined as the highest measurement you can achieve in the middle of a good day, after using your inhaled bronchodilator.
Your allergist can help you determine your personal best by using treatment to normalize your lung function, and then
accurately measuring lung function using a highly sensitive in-office measurement machine called a spirometer. Lung function values can then be compared to your own peak flow device to set your personal asthma management goals.
For children, peak flow goals should not decrease over time, but should be readjusted upward on a yearly basis to account for growth
"PFTs", or pulmonary function testing, is simply the evaluation of
PFTs are used to determine:
the presence of lung disease or abnormality of lung function
the extent of abnormalities
the extent of impairment caused by abnormal lung function
the progression of the disease the nature of
the physiologic disturbance
a course of therapy and treatment, as indicated
As you may have experienced, seeing your PFT
results can be quite overwhelming. It is my hope that this
simplification of what the abbreviations (i.e. FVC) mean, as well as the observed values, will help you to
understand your own test results. Obviously, not all the measured values on your test have as much
significance as others, therefore, I will try to define and discuss only those which are most commonly
measured and have the most significance.
Normal: for comparative purposes, observed values that fall at 80% or greater than the predicted values.
Predicted Values: these are average numbers based upon one's age, height,
sex, and at some institutions,
A. Pulmonary mechanics
1. FVC - Forced Vital Capacity is the maximum volume of gas that can be
forcefully and rapidly expired
after a maximal inspiration. This maneuver may also be called a "Flow-Volume Loop", which is the same
maneuver that is graphically displayed comparing volume and flow rate. significance: May be normal or
reduced in emphysema because of loss of support for small airways.
2. FEV1 - Forced Expiratory Volume after 1 second is the volume of gas
expired after one second from
the beginning of the FVC maneuver. significance: Usually decreased in obstructive airways due to mucus
secretion, bronchospasm, inflammation, or loss of elastic support of the airways themselves, as in
3. FEV1/FVC - The ratio of FEV1 to FVC expressed in a percentage. significance:
usually decreased in
obstructive airways and is independent of the relative values of FVC and FEV1.
4. FEF 25-75% - Forced Expiratory Flow from 25 to 75%, is the average rate
of flow during the middle
half of an FVC maneuver based upon a segment of the FVC that included the flow from medium-sized and
small airways. Also known as "mid flow rates". significance: usually decreased in obstructive airways due to
mucus secretion, bronchospasm, inflammation, or loss of elastic support of the airways (i.e.emphysema).
5. FEFMAX or PEFR - Forced Expiratory Flow at Maximum effort or Peak Expiratory
Flow Rate, is the
maximum flow rate attained during the FVC maneuver. significance: Generally, FEFMAX is a good index
of the patient's effort and relative strength in forceful exhalation. Also, may have relative meaning in
evaluation of the effectiveness of a patient's cough.
6. Raw - Airway resistance is the "resistance" created by the airways and
the friction against the walls of the
airways caused by the flow of air through these passageways. This test is performed in the so-called "body
box" or Plethysmograph, where one performs "panting" maneuvers. significance: Raw is increased in
emphysema because of narrowing and collapse in some of the larger airways, as well as more distal
bronchioles. "Normal" would be a value which is less than the predicted value.
B. Lung volumes
"Air-trapping" - a term used to describe the state where one actually maintains
a large amount of air in one's
chest, even at the end of both normal and maximal exhalation.
1. SVC - Slow Vital Capacity is the volume of gas measured on a slow, complete
expiration after or before
a maximal inspiration, without forced or rapid effort. significance: often the SVC is significantly larger than
FVC, which indicates to some degree the existence of air-trapping. Generally, with obstructive lungs, SVC
is within normal limits. It may be less than normal due to the collapse of airways due to lack of support.
2. FRC or TGV - Functional Residual Capacity, or Thoracic Gas Volume, is
the volume of gas remaining in
the lungs after exhalation of a normal breath. This test is performed in several different ways. Perhaps the
most accurate is by the "body box"; other less accurate ways (especially in light of poorly communicating
airways) include the Nitrogen Washout method, Helium Dilution, and Single-Breath Nitrogen Washout.
significance: relative to the predicted values, larger values of FRC or TGV indicate the degree of
air-trapping (i.e. emphysema).
3. RV - Residual Volume is the volume of gas remaining in the lungs after
complete exhalation. Value is
obtained by any of the above methods mentioned for FRC.significance: Like FRC, RV is compared to the
predicted values to determine the degree of air-trapping.
4. TLC - Total Lung Capacity is the volume contained in the lungs at the
end of a maximal inspiration. This
value is obtained from determination of SVC and FRC, in methods previously mentioned. significance:
because of air-trapping associated with emphysema, the TLC is usually larger than predicted.
C. Diffusing capacity
DLCO - Diffusing Capacity measures the transfer of a diffusion-limited
gas (Carbon Monoxide, CO 0.3%)
across the alveolocapillary membrane. CO combines with hemoglobin approximately 210 times more
readily than oxygen does. In the presence of normal amounts of hemoglobin and normal ventilatory function,
the primary limiting factor of diffusion of CO is the status of the alveolocapillary membrane. significance:
DLCO is usually decreased in emphysema because of the decrease in the total surface area, loss of
capillary bed, increased distance from terminal bronchiole to alveolo capillary membrane, and the
mismatching of ventilation to blood flow.
D. Other measurements
1. ABG - Arterial Blood Gasses are samples drawn from an artery (usually
the radial near one's wrist),
which enables us to measure the following values:
1.PH - the measurement of your arterial blood's acid-base balance. This
"balance" is controlled by several
factors, but primarily metabolism and ventilation. If there is an imbalance with one or the other or both,
there will be a definite effect on the PH. The approximate "normal" range of PH is 7.335 to 7.45, with 7.4
being the mean. Values less than 7.4 are considered to be more "acidic", while those greater than 7.4 are
more basic or "alkaline".
2.PaCO2 - Partial Pressure of Carbon Dioxide in arterial blood. This value
is an indicator of how
effectively your lungs are able to rid themselves of a by-product of metabolism, CO2. The "normal" range
for PaCO2 is 35 to 45 mm Hg. Elevated values greater than 40-45 mainly indicate that the lungs are not
able to rid themselves of the CO2 ("CO2 retainer"). This may be evident in emphysema, where much of the
lungs are unable to effectively exchange gasses.
3.PaO2 - Partial Pressure of Oxygen in arterial blood. This is a measure
of the actual amount of oxygen
there is in your arterial blood. The "normal" for PaO2 is generally greater than 75-80 mm Hg, relative to
your age. For the most part, it should be greater than 55-60 mm Hg, otherwise supplemental oxygen would
be indicated. (Note of caution: More is not always better. For those of you on supplemental oxygen, please
contact your physician before you significantly increase your O2 flow).
2. PULSE OXIMETRY or SaO2 - This is a non-invasive measure of one's oxygen
saturation; that is, the
amount of oxygen saturated in one's hemoglobin in terms of a percentage. This is not as accurate as the
values obtained from an ABG and should only be used as a gauge of one's oxygenation. Normal ranges are
between 95-100%. Supplemental oxygen is not generally instituted unless SaO2 is less than 88-90% at
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last edited on 4-3-2002