Respiratory Physiology & Neurobiology 199 (2014) 34–40
Contents lists available at ScienceDirect
Respiratory Physiology & Neurobiology
journal homepage: www.elsevier.com/locate/resphysiol
Dalhousie Dyspnea and Perceived Exertion Scales: Psychophysical
properties in children and adolescents
Paolo T. Pianosi a,∗ , Marianne Huebner b , Zhen Zhang b , Patrick J. McGrath c
a
b
c
Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN 55905, USA
Department of Statistics and Probability, Michigan State University, East Lansing, MI 48824, USA
Department of Community Health and Epidemiology, Dalhousie, Halifax, NS, Canada B3H 4J1
a r t i c l e
i n f o
Article history:
Accepted 18 April 2014
Available online 30 April 2014
Keywords:
Adolescents
Children
Exercise
Dyspnea
Perceived exertion
a b s t r a c t
Children and adolescents vary widely in their perception of, or capacity to rate, sensations during exercise using the Borg scale. We sought to measure sensory-perceptual responses obtained using Dalhousie
Dyspnea and Perceived Exertion Scales in 79 pediatric subjects during maximal exercise challenge and
to determine the psychophysical function relationship(s). Concurrent validity was assessed by canonical plots of mean ratings on either scale, which showed showing very good correlations for perceived
leg exertion vs work, and dyspnea vs ventilation. Both scales yielded similar results with respect to
goodness of fit regardless of whether data was fitted to a power or quadratic function provided a delay
term was included. The quadratic model fixed the exponent of the power law at 2 but, unlike a power
model, allowed characterization of individual responses that increased and then plateaued. Dalhousie
Dyspnea and Perceived Exertion Scales offer an alternative to Borg scale during exercise in pediatric
populations.
© 2014 Elsevier B.V. All rights reserved.
1. Introduction
Many scales have been employed to measure dyspnea but the
most commonly employed is the Borg scale and modifications
thereof (Borg, 1962, 1982, 1998). These were developed and studied in adults to rate the distinct but related sensation of perceived
exertion. The use of perceptual-sensory scales in children is more
problematic. A prerequisite for use of any scale is the subject’s
ability to seriate – organize objects in order – something that generally reaches an operational stage around 7 years of age (Mareschal
and Shultz, 1999). There have been numerous attempts to measure perceived exertion during exercise using a variety of scales
in children, reviewed by Eston and Parfitt (2007), who opined that
adult-derived methods and applications may not be appropriate
for use in pediatric populations. For this reason, other scales have
been developed for use in pediatric populations, arguably the most
widely used of which is the OMNI scale (Robertson et al., 2000; Utter
et al., 2002). Its validation as a measure of dyspnea or perceived
∗ Corresponding author at: MA E-16, Department of Pediatric and Adolescent
Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Tel.: +1 507 538 0127; fax: +1 507 284 0727.
E-mail addresses: pianosi.paolo@mayo.edu (P.T. Pianosi), huebner@msu.edu
(M. Huebner), zhang@stt.msu.edu (Z. Zhang), Patrick.McGrath@dal.ca (P.J. McGrath).
http://dx.doi.org/10.1016/j.resp.2014.04.003
1569-9048/© 2014 Elsevier B.V. All rights reserved.
exertion has gained traction largely by comparing OMNI ratings
with those obtained using the Borg 6-20 RPE scale (Pfeiffer et al.,
2002). The children’s OMNI scale, despite its appearance of showing
a cyclist pedaling uphill, has been used to quantitate all perceptual
ratings accompanying exertion, i.e. overall body (RPE-Overall), legs
(RPE-Legs), and chest (RPE-Chest).
The Borg scale has undergone evolution since its original conception as the 6-20 RPE scale. Indeed, the respiratory literature
and more recent work (Borg and Kaijser, 2006) has explored
the psychophysical function obtained using Borg’s category ratio
(CR-10) scale. This research has shown that ratings for dyspnea
and leg effort in adults conform to a power law function: S = kIa
where S is the magnitude of the particular sensation of interest
(e.g. dyspnea), I is the intensity of stimulus (e.g. ventilation), k is
constant, and a is the exponent, with exponents in adults averaging ∼1.6 (Killian et al., 1992). There has been no such analysis
among pediatric subjects using any Borg scale or the OMNI scale,
but the convergence of developmental understanding at an age
when a child can adequately perform spirometry and a maximal
exercise test offers the opportunity to conduct psychophysical investigations of dyspnea and perceived exertion in this
population.
We designed pictorial scales to measure dyspnea and perceived
leg exertion during exercise that involves predominantly work
by leg muscles. Scale design has been described (McGrath et al.,
P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
35
Fig. 1. Dalhousie Dyspnea and Perceived Exertion Scales.
2005) and the scales accurately tracked dyspnea during histamineinduced bronchoconstriction (Pianosi et al., 2006). We recently
showed that ratings of perceived exertion obtained using the Borg
CR-10 scale in children and adolescents conformed equally well
to a quadratic function as to a power function, but goodness of fit
was improved by introducing a delay term to account for the lag
observed before these sensations were perceived (or reported) to
exceed resting levels (Huebner et al., 2014). The aims of the present
report were to demonstrate concurrent validity and describe the
trajectory of dyspnea and perceived exertion ratings obtained using
these pictorial scales in children and adolescents. We hypothesized that Dalhousie Dyspnea and Perceived Exertion Scales ratings
would rise with increasing work in a manner or trajectory similar
that seen using the Borg CR-10 scale.
2. Participants and methods
2.1. Participants
Children with asthma or cystic fibrosis attending outpatient
clinics at IWK Health Centre in Halifax, Canada were invited to participate. Healthy control children were recruited from friends and
relatives of hospital personnel, or siblings of the patients. The study
received approval from the Research Ethics Board of the IWK Health
Centre, and parents or mature minors signed informed consent.
2.2. Procedures
Ventilation and gas exchange were measured breath-by-breath
(CPX Plus, WE Collins, Braintree, MA, USA) and averaged every
15 s during each stage of exercise on a cycle ergometer (Collins)
test employing step increments of either, 50, 100, or 150 kpm
per minute depending on size and age. Increments were chosen
to achieve test duration of 6–10 min, until voluntary, symptomlimited, exhaustion.
2.3. Symptom measurement
The Dalhousie Dyspnea and Perceived Exertion Scales consist of
a sequence of pictures depicting three, dyspnea constructs: chest
tightness, throat closure, and breathing effort; plus an additional
pictorial scale to depict leg exertion/fatigue (Fig. 1). The research
assistant gave participants an explanation of the pictorial scales at
the outset as follows:
“The purpose of this test is to see how your breathing feels and how
your legs feel during exercise. There are no right or wrong answers.
The pictures in front of you show how your breathing might feel,
from no difficulty at all, to the most difficulty you can imagine. You
might feel this difficulty breathing in your chest or in your throat.
Another scale simply asks you to tell us how hard it is to breathe
– from nothing at all, to the hardest breathing imaginable. With
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P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
the final set of pictures, tell us how your legs feel – from nothing at
all, to the hardest imaginable. We will ask you the same using this
other scale (pointing to the Borg CR-10).
Ratings using the pictorial scales at rest and during exercise
were prompted by the questions:
“How does your breathing feel?” or “How do your legs feel?”
While, ratings using the Borg scale were prompted by the questions:
“How hard is your breathing?” or “How tired are your legs?”
2.4. Analysis
Canonical curves plot actual ratings from the Dalhousie scales
vs average ratings of the Borg scale, and actual ratings from the
Borg scale vs average ratings of the Dalhousie scales, at each work
load relative to individual maxima. Similar curves would indicate
that ratings on one scale can be mapped well to the other scale.
Functional clustering algorithms were used to identify patterns,
related to any of age, sex, or diagnosis (healthy or lung disease)
of dyspnea or perceived exertion ratings during exercise.
For the mathematical description or modeling of the sensoryperceptual function, we began with the general form was proposed
by Borg (1962):
c
where S describes the sensation, b is a measure constant, a the absolute threshold or the starting point of the function, d a delay before
the sensation rises above this threshold, c is the exponent, and I the
intensity of the stimulus, but used a simpler quadratic model with
delay:
+
+ 2
S = a + b1 (I − d) + b2 ((I − d) )
M:F
Age (years)
Height (cm)
Weight (kg)
FEV1 (%predicted)
V̇ O2 (mL min−1 kg−1 )
HR (min−1 )
V̇E (L min−1 )
Controls
CF
Asthma
17:15
12.4 ± 2.5
155 ± 13
51.9 ± 15.9
103 ± 17
36.0 ± 10.1
193 ± 9
77.8 ± 22.3
15:6
14.1 ± 2.3
158 ± 11.6
48.7 ± 11.1
75 ± 18
28.7 ± 8.3
185 ± 15
77.8 ± 18.1
14:12
12.0 ± 2.8
150 ± 14
45.8 ± 16.4
96 ± 16
33.4 ± 8.7
189 ± 1I
77.6 ± 24.0
FEV1 , 1st second forced expiratory volume. V̇ O2 , oxygen uptake. V̇E , ventilation.
Ratings were recorded at rest and during the final 15 s of each
workload. Pictorial scales were mounted on a large poster board
in front of the participant. Sliding cursors located below each set
of pictures arranged in rows, were pushed along its track from left
to right by the research assistant until it pointed to the rating that
best described the participant’s level of dyspnea (each of three subscales) or leg effort, signaled as the participant pushed a buzzer
mounted on the handlebars. The cursor was replaced at the far
left (0-point) after each measurement, the in preparation for the
next. An identical procedure was done with the Borg CR-10 Scale
mounted on a clipboard in front of the subject, only the cursor was
(by scale design) was slid vertically until the subject signaled with
the buzzer. Subjects were asked which scale they preferred after
completion of exercise.
S = a + b(I − d)
Table 1
Characteristics and maximal exercise data (means ± SD) of subjects.
where the superscript “+” indicates the non-negative part. Both
power and quadratic delay model fit equally well, but a quadraticdelay model simplifies the interpretation since it has a fixed
exponent and only the coefficients of the quadratic and linear terms
need to be estimated (Huebner et al., 2014). A non-zero coefficient
(b2) measures the strength of the curvature but if this coefficient
is zero, then the curve is linear. The computational burden for the
quadratic delay model was much smaller than for the power-delay
model, using the statistical software R 2.15.3 for analyses. The root
mean square error (RMSE) was calculated to assess the model fits,
with lower RMSE implying better statistical fit.
3. Results
Anthropometric, lung function, and exercise data on study subjects is shown in Table 1. Children and adolescents preferred the
Dalhousie pictorial scales to the Borg Scale for rating dyspnea as
well as leg exertion (70% and 80% of participants, respectively).
All 79 subjects had at least six paired ratings. Subjects generally
tracked their sensation of dyspnea and perceived leg exertion similarly using the Borg and Dalhousie scales, and those reporting
minimal change in dyspnea or perceived exertion did so whether
rated by Borg or Dalhousie scales. Mappings from Dalhousie to Borg
scale ratings and vice versa were similar, as shown in the canonical curves (Fig. 2). The paired curves diverge in heavy exercise
due to lower number of subjects rating dyspnea or perceived exertion in this range. Subjects also rated dyspnea similarly with each
sub-scale of the Dalhousie scales (breathing effort, chest tightness,
throat closure).
Results of modeling stimulus-response curves in, reported as
medians (quartiles) of the model parameters for all scales, are
shown in Table 2. In this table, one can see that the median value
for the coefficient of the quadratic term was 0 for all scales except
dyspnea rated with the Dalhousie pictorial scales. A median of
0 for the quadratic coefficient or a median of 1 for the exponent
indicate that some curves were linear; and about as many subjects
Table 2
Summary of estimated model parameters for models: median (1st quartile, 3rd quartile) ratings of perceived exertion and dyspnea, using Borg CR-10 scale or using Dalhousie
scales.
Parameters
Dalhousie-leg exertion
vs %Wmax
Borg-exertion vs %Wmax
Dalhousie-breath effort vs
%max V̇E
Borg-dyspnea vs
%max V̇E
Quadratic-delay model: S = a + b1 (I − d)+ + b2 ((I − d)+ )2
Intercept (a)
1.18 (1.0, 2.0)
Delay (d)
0.26 (0.2, 0.4)
Coefficient of linear term (b1 )
4.32 (2.4, 7.0)
Coefficient of quadratic term (b2 )
0.0 (−3.2, 2.9)
0.23 (0.2,0.3)
RMSE
0.39 (0.0, 0.6)
0.40 (0.3, 0.5)
7.01 (3.2, 11.9)
0.0 (−4.3, 5.8)
0.25 (0.2, 0.4)
1.06 (1.0, 1.6)
0.28 (0.2, 0.4)
6.24 (4.2, 8.2)
−2.19 (−6.0, 0.5)
0.24 (0.2, 0.3)
0.38 (0.03, 0.6)
0.34 (0.24, 0.5)
7.25 (3.3, 11.9)
0.0 (−6.2, 2.8)
0.25 (0.2, 0.4)
Power-delay model: S = a + b (I − d)c
Intercept (a)
Delay (d)
Coefficient of power term (b)
Exponent (c)
RMSE
0.36 (0.0, 0.6)
0.30 (0.2, 0.4)
6.99 (5.4, 10.5)
1.03 (0.8, 1.8)
0.23 (0.1, 0.4)
1.02 (1.0, 1.6)
0.30 (0.2, 0.4)
4.22 (2.9, 6.0)
0.69 (0.3, 1.0)
0.23 (0.1, 0.3)
0.38 (0.06, 0.7)
0.34 (0.24, 0.4)
6.81 (4.2, 9.8)
0.88 (−0.6, 2.8)
0.25 (0.2, 0.4)
1.20 (1.0, 2.0)
0.25 (0.2, 0.4)
4.89 (3.5, 6.2)
0.97 (0.6, 1.5)
0.22 (0.2, 0.3)
P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
37
Fig. 2. Canonical plots of actual ratings from one scale, vs average ratings of the alternative scale at each work load, relative to individual maxima.
had a quadratic increase in ratings in heavy exercise as there were
subjects whose ratings leveled off with increasing work. Great
variability in growth pattern and trajectory is evidenced in the
functional clustering diagrams (Fig. 3). Regardless of what scale
was used, a delay in onset of ratings of perceived exertion or dyspnea increasing above baseline values was seen in many individuals.
That is to say, ratings remained relatively constant until a certain
threshold – averaging ∼40% maximum exercise. There was no
Table 3
Cluster analysis of psychophysical functions (Fig. 3) split according to age, sex, diagnosis.
Scale rating cluster
N
Male
<13 year
Asthma
CF
Control
Dalhousie-leg exertion
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Cluster 5
Cluster 6
Cluster 7
Cluster 8
Cluster 9
5
7
7
5
6
8
5
15
21
4
5
3
3
5
5
2
7
12
1
1
4
4
3
2
3
6
13
2
4
4
4
1
1
1
3
6
2
2
1
1
3
3
2
5
2
1
1
2
0
2
4
2
7
13
Borg-exertion
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Cluster 5
Cluster 6
Cluster 7
Cluster 8
Cluster 9
17
9
1
8
17
6
6
10
5
9
4
1
5
11
3
4
6
3
6
3
0
4
11
1
4
8
0
4
2
0
5
5
3
1
5
1
6
3
1
1
2
1
2
1
4
7
4
0
2
10
2
3
4
0
Dalhousie-breath effort
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Cluster 5
Cluster 6
Cluster 7
Cluster 8
Cluster 9
4
10
5
15
7
7
8
10
13
2
3
4
10
4
4
7
6
6
2
3
2
8
1
2
5
7
7
2
5
1
2
2
2
3
7
2
0
2
2
6
1
2
2
1
5
2
3
2
7
4
3
3
2
6
Borg-dyspnea
Cluster 1
Cluster 2
Cluster 3
Cluster 4
Cluster 5
Cluster 6
Cluster 7
Cluster 8
Cluster 9
6
10
4
4
10
4
10
18
13
3
8
2
3
5
3
6
10
6
2
7
1
3
5
1
2
13
3
3
6
2
1
0
1
3
6
4
2
2
0
0
5
2
3
2
5
1
2
2
3
5
1
4
10
4
38
P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
Fig. 3. Results of cluster analysis of individual response ratings for dyspnea and perceived exertion obtained with the Borg CR-10 scale; and those obtained with the
corresponding Dalhousie scale pictures, specifically the breathing effort and leg exertion constructs.
clear distinction in the clustering of growth trajectories obtained
using each scale with respect to age, gender, or diagnosis (Table 3).
In-depth analysis of these data was limited due to small numbers
of subjects in any particular group: e.g. 2/3 of subjects in cluster
1 of Fig. 3(2) (Borg CR-10 rating of perceived exertion) were >13
years old but the total number of subjects in that cluster was only
17. It is also evident from Fig. 3 that many subjects reported well
below maximal possible values for dyspnea or leg exertion at peak
exercise. One can see in Table 4 that younger children (ages 8–12)
had lower ratings for dyspnea and perceived exertion at maximal
exercise than did adolescents (ages 13–18) on all scales except the
Dalhousie breathing effort sub-scale.
4. Discussion
We compared Dalhousie Dyspnea and Perceived Exertion Scale
ratings with Borg CR-10 ratings of dyspnea and leg exertion
from adolescents and children as young as 8 years of age during
exercise – healthy or with lung disease – and found very good
coupling between corresponding measurements. Ours is the first
P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
Table 4
Maximal ratings for dyspnea and perceived exertion obtained using Borg CR-10 or
Dalhousie pictorial scales.
Scale
Age (years)
Median (IQR)
p-Value
Dalhousie-leg exertion
(maximum = 7)
Borg-exertion
(maximum = 10)
Dalhousie-breath effort
(maximum = 7)
Borg-dyspnea
(maximum = 10)
8–12
13–18
8–12
13–18
8–12
13–18
8–12
13–18
4 (4–6)
6 (4.25–6)
4 (3–6)
6 (4.25–8)
4 (3–6)
5 (4–5.75)
4 (3–6)
5 (4–7)
0.012
0.013
0.006
0.009
0.23
0.22
0.019
0.04
IQR inter-quartile range. p-values for Wilcoxon test comparing medians.
psychophysical and modeling study of Borg CR-10 scale in a pediatric population. Dalhousie Scale ratings paralleled Borg ratings,
though neither scale conformed to a simple power law relationship in children. The psychophysical model fit was improved by
adding a delay term to the stimulus–response function. Allowance
for this delay yielded average exponent values slightly lower than
previously reported in adults (Borg, 1998; Killian et al., 1992), but
similar to those estimated by Borg and Kaijser (2006). In that report,
curves for adults were similar (with perhaps one exception) and
thus average model parameters could be estimated for the study
population. In contrast, individual curves for pediatric subjects in
our study were much more variable and were not comparable to
those reported in adults. Linear or exponential (quadratic) growth
of the psychophysical function for dyspnea or perceived exertion
posed a challenge in modeling the sensory–perceptual responses
in our pediatric population. Both a power model with delay term
and a quadratic-delay model can describe either linear or quadratic
growth of dyspnea or perceived exertion, but only the quadraticdelay model accounted for inflection points. One can see these
when ratings increase and then plateau in which case the coefficient of the quadratic term is negative (Huebner et al., 2014). The
model fits were equally good for the pictorial Dalhousie Dyspnea
and Perceived Exertion Scales or the Borg scales indicated by similar RMSE. Canonical curves indicated that ratings on these different
scales mapped each other well, demonstrating concurrent validity of the Dalhousie scales. We had previously demonstrated their
content validity for estimation of dyspnea severity (McGrath et al.,
2005; Pianosi et al., 2006).
Killian (1999) argued that the Borg CR-10 scale in adults adheres
to principles of an absolute scale with ratio properties. Dalhousie
Dyspnea and Perceived Exertion Scales function at least as interval
scales and statistical modeling of a quadratic function to describe
stimulus–response relationships implies they behave as ratio scales
as well. They have an anchor (intercept) but the concepts of weaker
vs stronger or weak–strong absolutes are embodied in the pictures
themselves instead of numbers or adjectives. A particular picture
replaces, or serves as the equivalent of, the descriptive adjectives
tagged with numbers along the Borg CR-10 scale. These concepts
were correctly identified and pictures correctly sequenced by the
vast majority of pediatric subjects more than 7 years old during
initial validation studies (McGrath et al., 2005).
In our modeling analysis, we identified nine clusters of trajectories for perceived exertion vs percent maximal work capacity,
or dyspnea vs percent maximal ventilation. Such patterns in ratings were distinguished by size of delay as workload increased,
linear or quadratic growth patterns, and highest rating at peak exercise. Collectively, these characteristics accounted for the marked
inter-individual variability in the observed sensory–perceptual
responses. Therefore, an attempt to parse these characteristics
might provide insights into better understanding of this variability
and how cognitive ability impacts rating of sensation. Studies in
adults using the Borg CR-10 scale also showed an initial period in
39
light exercise of very gradual rise in rating (Killian et al., 1992). Most
of our pediatric subjects appeared to perceive little if any change
in sensation of dyspnea or perceived exertion until they exceeded
a threshold – generally ∼40% of peak exercise but >60% in some –
after which ratings rose with highly variable degree of steepness.
Since this observation was no more prevalent in healthy subjects
than in patients with lung disease, the phenomenon may be more
characteristic of the pediatric population as a whole.
Median or mean maximal ratings for dyspnea and leg exertion
among our pediatric subjects were only slightly greater than half
the maximum possible value, a finding reported by others (Barkley
and Roemmich, 2008; Bar-Or, 1977). Younger children had lower
ratings than did children over 13 years of age (Huebner et al., 2014).
Sub-maximal rating was also seen in 80% of 460 adults (Killian et al.,
1992) who explained their observations as reflecting tolerance for
discomfort. It is hard to imagine the degree of physiologic stress
was so different at peak exercise between younger vs older children.
Groslambert and Mahon (2006) argued that pre-pubertal children
could distinguish up to four levels of exercise intensity during cycle
ergometry. It may be that children cannot conceptualize maximum
dyspnea or perceived exertion beyond the fourth-highest rank on
any scale because experiential poverty impairs their ability to estimate the greatest imaginable perceived leg exertion at maximal
exercise (Groslambert and Mahon, 2006).
Several other scales have been proposed to measure perceived
exertion (mainly) or dyspnea (fewer) in children (reviewed in Eston
and Parfitt, 2007; Schweitzer and Marchal, 2009). Among these,
the OMNI scale has been studied most extensively and compared
with Borg scale ratings in children and adolescents (Robertson
et al., 2000; Pfeiffer et al., 2002; Utter et al., 2002). The Dalhousie Perceived Exertion scale shares some features of the OMNI
scale, which combined pictures and verbal descriptors, recognizing
the limitations of numerical and verbal descriptions. While OMNI
and Dalhousie Scales are conceptually similar, OMNI employs the
same scale to assess undifferentiated rating of perceived exertion
(overall-RPE), as well as RPE-legs and RPE-chest. The Dalhousie
Dyspnea Scales were created primarily as a tool to measure degree
of dyspnea including the overall sense of breathing effort after
interviewing healthy children and children with lung disease; and
secondly perceived exertion with specific focus on the legs – the
principal muscle groups involved in laboratory-based ergometry.
As such, a child as young as 7 years of age can choose the picture
most closely depicting how s/he feels in her/his chest or throat,
rather than trying to represent or extrapolate a breathing sensation
to caricature of a cyclist pedaling uphill. Moreover, psychophysical modeling of the stimulus–sensory perceptual response has not
been performed with any of these other pictorial scale such as
OMNI to the best of our knowledge. A limitation of our study is
that the models were estimated from one trial. It would be useful
to assess the children in a second trial to observe any changes in the
functional relationship and increasing comfort with the process of
rating.
The word “dyspnea” subsumes a variety of uncomfortable
respiratory sensations, distilled into (at least) three separable
qualities in adults: “air hunger”, “effort”, and “tightness”. Rather
than presume the same sensations would be reported by children
and adolescents, we developed pictorial scales that embodied
sensations gleaned from focus group interviews of children with
the commonest pediatric pulmonary diseases. The most articulate
of these initial subjects were quite clear in differentiating chest
tightness such as one might report during bronchoconstriction,
from breathing effort such as one feels during or immediately
following vigorous aerobic exercise. The sensation of throat constriction also came out loud and clear, despite the fact that none of
the initial focus group subjects had a history of glottic disorder. The
fact that we were unable to demonstrate differential responses or
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P.T. Pianosi et al. / Respiratory Physiology & Neurobiology 199 (2014) 34–40
sub-scale choices in healthy controls vs. children with asthma or
cystic fibrosis does not refute or exclude the possibility that these
three pictorial scales reflect different dyspnea attributes appropriately in both healthy controls and individuals with lung diseases.
We previously showed that asthmatics reported a sensation in
their throat during bronchoconstriction, and our study was underpowered to find such distinctions given the large inter-individual
variability in severity of dyspnea demonstrated during exercise.
In conclusion, Dalhousie Dyspnea and Perceived Exertion Scales
and Borg CR-10 scales resulted in a similar model fit. Since the pictorial scales do not rely on any numbers or verbal descriptors, it
may be possible to use the Dalhousie scales in children without
regard to language. Further research would be warranted to examine such relationships in other populations. Still, the choice of scale
may be less important than recognition of individual variability in
stimulus–perception relationship.
Acknowledgements
Funding for this study was provided by the Lung Association
of Nova Scotia, and by the Department of Pediatric and Adolescent Medicine Small Grants Program. This publication was made
possible by CTSA Grant Number UL1 TR000135 from the National
Center for Advancing Translational Sciences (NCATS), a component
of the National Institutes of Health (NIH). Its contents are solely the
responsibility of the authors and do not necessarily represent the
official view of NIH.
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