|
Peak Expiratory Flow Rate (PEFR) is an
important parameter in the management of bronchial asthma. Measurement
of PEFR in bronchial asthma is similar to measurement of blood pressure
in managing hypertension and meausrement of blood glucose in managing
diabetes mellitus. Peak expiratory flow provided a simple quantitative
and repro-ducible measure of resistance and severity of airflow
obstruction. Peak expiratory flow can be measured with inexpensive and
portable peak expiratory flow meter. Peak flow monitoring can be used
for short term monitoring, managing exacerbations and daily long term
monitoring. When used in these ways, the patient’s measured personal
best is the most appropriate reference value(1).
Many normograms are available for peak expiratory
flow rate in children. Though the patient’s measured personal best is
the most appropriate reference value, in office practice, to assess a
patient’s appropriate peak expiratory flow rate, we have been using a
formula as follows:
PEFR = (Ht – 100) × 5 + 100
(Ht = Standing height in cm)
We find that this formula serves as a rough tool for
calculating the expected peak expiratory flow rate for individual
patients. We have also compared PEFR values obtained from our formula
with those obtained from frequently used and quoted prediction equations
and normograms in Table I. Comparison of mean of PEFR values for
three standing heights with PEFR values obtained for the same heights
from our formula is shown in Table II. There is also a close
correlation of PEFR prediction curves of the proposed formula with those
of other (Fig. 1).
Mnemonics for parameters such as weight, height and
blood pressure have been widely used by Pediatricians. In a similar
vein, we propose that the above described formula can be used
effectively, in office practice, for quick assessment of asthmatic
children with a height of 100 cm and more.
Table I__PEFR Values From Our Formula and Other Prediction Equations and Normograms
|
Standing
height (cm)
|
PEFR |
|
Proposed formula
|
Swaminathan(2)
|
Hsu(3)
|
Godfrey(4)
|
|
110
|
150
|
160.06
|
171
|
NA*
|
|
115
|
175
|
179.91
|
190
|
NA*
|
|
120
|
200
|
199.76
|
210
|
212
|
|
125
|
225
|
219.61
|
232
|
NA*
|
|
130
|
250
|
239.46
|
254
|
NA*
|
|
135
|
275
|
259.31
|
279
|
NA*
|
|
140
|
300
|
279.16
|
304
|
318
|
|
145
|
325
|
299.01
|
330
|
NA*
|
|
150
|
350
|
318.86
|
358
|
NA*
|
|
155
|
375
|
338.71
|
388
|
NA*
|
|
160
|
400
|
358.56
|
418
|
423
|
|
165
|
425
|
378.41
|
450
|
NA*
|
|
170
|
450
|
398.26
|
489
|
NA*
|
|
175
|
475
|
418.11
|
518
|
NA*
|
|
180
|
500
|
437.96
|
554
|
NA*
|
NA* : Data not available.
Table II__Comparison of PEFR Values From Our Formula with Mean From
Two Available Prediction Equations and One Normogram+(2-4)
|
Standing
height (cm)
|
Mean of PEFR
values+
|
PEFR values
from our formula
|
|
120
|
207.25
|
200
|
|
140
|
300.39
|
300
|
|
160
|
399.85
|
400
|
Fig.
1. PEFR values plotted against standing height. Comparison of PEFR
prediction curves obtained from the proposed formula with those of other
authors(2-4).
S. Balasubramanian,
N.R. Ravikumar,
Elavazhagan Chakkarapani,
S.O. Shivbalan,
Department of Pediatrics,
Kanchi Kamakoti Childs Trust Hospital,
12 A, Nageswara Road,
Nungambakkam,
Chennai 600 034, India.
E-mail: [email protected]
| 
