Transcript A small device with great importance

A small device with great
importance
Presented by : Dr. Jalal Mohsin Uddin
DTCD, FCPS (Pulmonology)
What is Peak Flow Meter ?
• A peak flow meter is an inexpensive, portable,
handheld device for those with asthma that is
used to measure how well air moves out of their
lungs.
• The peak flow meter works by measuring how
fast air comes out of the lungs when person
exhale forcefully after inhaling fully. This measure
is called a "peak expiratory flow," or "PEF.“
• Keeping track of PEF, is one way patient can
know if his symptoms of asthma are in control or
worsening.
• It is important to know that peak flow meter
only measures the amount of airflow out of
the large airways of the lungs. Changes in
airflow caused by the small airways (which
also occur with asthma) will not be detected
by a peak flow meter.
• Small airway disease (SAD), defined by a
reduction in forced expiratory flow at 25-75%
of the pulmonary volume (FEF25-75).
• The peak expiratory flow
(PEF), also called peak
expiratory flow rate
(PEFR) is a person's
maximum speed of
expiration.
• Normal expected value
depends on a patient's
sex, age and height.
Definition of PEFR :
• The peak expiratory flow rate (PEFR, also
known as a peak flow) is the maximal rate
that a person can exhale during a short
maximal expiratory effort after a full
inspiration.
• In patients with asthma, the PEFR percent
predicted correlates reasonably well with the
percent predicted value for the forced
expiratory volume in one second (FEV1).
• Peak expiratory flow is lowest in the early
morning and highest in the afternoon. If patient
wants to take the test only one time during the
day, they should take it first in the morning,
before using a bronchodilator medicine. Peak
flow rate can be measured upon awakening and
in the late afternoon or early evening.
• PEF varies throughout the day. In a person who
does not have asthma, it may vary between 10%
and 15%. In a person who has poorly controlled
asthma, it may vary more than 20%.
Personal best :
• A person's personal best is his or her highest peak flow.
This is the PEF, that will help the patient to find the
correct asthma zones. The personal best is used in the
self management plan that says what to do during a
sudden asthma attacks.
• One can determine his personal best by taking PEF
readings over 2 to 3 weeks when the asthma is under
control. During these weeks, peak expiratory flows
should be recorded at least twice daily. The personal
best is usually reached in the afternoon or evening.
Personal best measurements are never measured
during an asthma attack. personal best is the highest
reading you have over this period of time.
• Children need to have their personal best
measurement checked about every 6 months
to account for growth.
Peak flow chart of National Asthma
Council of Australia :
• The peak flow chart is available as a two-page
document in PDF format that one can download.
• The first page includes easy-to-follow instructions
for entering the peak flow measurements. The
second page is a chart that holds 8 weeks of
measurements. The pages should be printed
single-sided for easy reference.
• Print multiple copies of the second page if longterm monitoring is needed.
• The measurement of peak expiratory flow was
pioneered by Martin Wright, who produced
the first meter to measure lung function. The
original design of instrument was introduced
in the late 1950s, and the subsequent
development of a more portable, lower cost
version is the "Mini-Wright" peak flow meter.
Who Should Use a Peak Flow Meter?
• People with moderate-to-severe asthma
should have a peak flow meter at home.
• Even Peak flow meters are very helpful if a
child have moderate to severe asthma and
require daily asthma medications. Most
children ages 6 and up should be able to use a
peak flow meter .
How to use peak flow meter?
1) Move the marker to the bottom of the numbered
scale, and connect the mouthpiece to the peak flow
meter (if it isn't already connected).
2) Stand up if you're able.
3) Take a deep breath, filling your lungs completely.
4) Place your lips tightly around the mouthpiece. Blow as
hard and as fast as you can with a single breath.
5) Note the final position of the marker. This is your peak
flow rate.
6) Follow the steps above then blow into the peak flow
meter two more times. Record the highest reading of
the three.
Why it's done ?
1. To recognize early changes that may be signs of
worsening asthma and thus preventing asthma attack.
(Explanation : During an asthma attack, the muscles in
the airways tighten and cause the airways to narrow.
The peak flow meter alerts you to the tightening of
the airways often hours or even days before ,the
patient have any asthma symptoms. By using own PEF
with his/her asthma action plan, he/she will know
when to take his/her rescue asthma inhaler or other
asthma medicine. By following the steps in asthma
action plan, patient may be able to stop the narrowing
of the airways quickly and avoid a severe asthma
emergency).
2. Patient can learn what triggers their asthma.
3. It helps patient to decide whether their
asthma action plan is working well .
4. It helps patient to decide when to add or
adjust asthma medications.
5. The patient came to Know when to seek
emergency care.
Classification of Peak flow readings:
• Peak flow readings are often classified into 3
zones of measurement according to the
American Lung Association; green, yellow, and
red. Doctors and health practitioners can
develop an asthma management plan based
on the green-yellow-red zones.
Zones
Green zone
Yellow zone
Reading
80 to 100 percent of the usual
or normal peak flow readings
are clear.
Description
A peak flow reading in the green
zone indicates that the asthma is
under good control.
Indicates caution. It may mean
50 to 79 percent of the usual or respiratory airways are
normal peak flow readings
narrowing and additional
medication may be required.
Red zone
Less than 50 percent of the
usual or normal peak flow
readings
Indicates a medical emergency.
Severe airway narrowing may be
occurring and immediate action
needs to be taken. This would
usually involve contacting a
doctor or hospital .
Reversibility with PEF
• Take initial Peak Flow (PEF) measurement - best
of 3 good blows. Give salbutamol through
appropriate device.
• If 15 - 20 mins since salbutamol, take 2nd PEF
measurement
• Calculate percentage reversibility - Difference
between 1st & 2nd PEF X 100 1st PEF
measurement
• If less than 15%, consider other causes eg URTI;
COPD; cardiac; anaemia; cystic fibrosis; TB;
malignancy etc.
How to take care of Peak Flow Meter?
• Most peak flow meters require weekly
cleaning with warm water and a mild
detergent.