56 P
Medical Research Society
t h e end o f e x e r c i s e .
Breathing oxygen, r e s t i n g
SaO was 9 8 ?r 1%; t h e r e was no f a l l d u r i n g
exegcise.
E x e r c i s e d u r a t i o n on a i r was 364 f 73s
and on oxygen 444 t 105s.
Maximum v e n t i l a t o n
achieved was unchanged ( a i r 26 f 6 L/min; oxygen
A t any given work r a t e , VE was 8
26 r 7 L/min).
f 6% lower on oxygen than on a i r .
Breathlessness
r e l a t i v e t o work r a t e was lower i n 3 p a t i e n t s and
n o t d i f f e r e n t i n 2, when b r e a t h i n g oxygen.
In
each p a t i e n t t h e r e l a t i o n s h i p between VE and
breathlessness was t h e same whether b r e a t h i n g
oxygen o r a i r .
The improvement i n breathlessness d u r i n g
e x e r c i s e , when hypoxaemia was prevented, f o l l o w e d
t h e change i n v e n t i l a t i o n .
No separate
"dyspnogenic" e f f e c t could be d e t e c t e d .
161BREATELESSNESS DURING PROGRESSIVE AND STEADY
STATE EXERCISE IN NORMAL SUBJECTS
P A O'Neill, S C Allen, T B Stretton
and R D Stark
Department of Respiratory Medicine,
Manchester Royal Infirmary and Clinical
Pharmacology Unit, ICI Pharmaceuticals Division
Exercise tests may involve a progressive
increase of workload or attainment of a steady
state. We have compared the breathlessness
scores as measured by visual analogue scales
(VAS) during these two situations in healthy
subjects. Six normal volunteers who were not
otherwise involved with this study exercised on
a bicycle ergometer on two occasions, one
period at 50W and one at low, and for two
other periods when the load was increased by 25W
at minute intervals (25-15013).
The order of
these four periods of exercise was randomised
and the duration of each was six minutes.
Ventilation (tE), heart rate (HR) and oxygen
uptake ($0,) were measured continuously and
breathlessness was assessed by VAS at one
minute intervals.
Each volunteer was
familiarised with the tests beforehand and the
upper limit of the VAS was set on each study
day by a short period of exercise at a high
workload (2OOW 2 mins).
During the progressive tests the relationship
between breathlessness and ventilation was
reproducible for individual subjects. All
subjects achieved a steady state (assessed by
BR. (TE and t0 ) during exercise at the
fixed workloais. On the other hand, the
breathlessness score continued to increase
throughout these exercise periods.
During
progressive and steady state exercise the
breathlessness scores were similar both at
2 mins (5W)and at 4 mins (LOOW).
However,
the VAS values were significantly greater at
the 4 min time point (1OOW) in relation to
either 0 (PCO.01) or 00, (K0.05) during
progressfve exercise.
Thus a "steady state" of breathlessness was not
achieved during exercise at fixed workloads.
Moreover, we have demonstrated that the
relationahip of breathlessness to ventilation
or oxygen uptake was dissimilar during the two
modes of exercise.
16* SHORT BURST OXYGEN TBEBbpT FOR
BREBTHLESSNESS IN CHRONIC OBSTRUCl'IVE AIRWAYS
DISEASE
EVANS. T.W.
aJvl HOWARD, P
Royal H a l l w h i r e Hospital, Glossop Road,
Sheffield S10 2JF
Patients with chronic obstructive airways
disease prescribed oxygen at home by their
family doctor use it for short periods when
they feel breathless.
patients are
clinically normoxic. Fourteen patients with
advanced disease and variable h y p o x a d a were
exercised until they indicated severe
breathlessness o n a ID0 rn v i s d analogue
scale. Mr, 60 oxygen and air delivered
from a cylinder i n an identical manner to the
oxygen were randomly administered during
recovery periods after episodes of exercise.
Respiratory rate, heart rate and Pa02 estimated
by percutaneous electrode were measured
throughout the exercise and recovery periods.
Mean recovery time for breathlessness on
oxygen as j u Q e d by VA scale was significantly
shorter than during lacebo or air recovery
(p < 0.05,
0.027.
Nine of the fourteen
patients recovered after exercise faster on
oxygen than on placebo or air. The rate of
return to base line levels of respiratory and
heart rates were not significantly affected by
the gas inhaled. No placebo effect was d e t e c a e
>
The mean value indicating a reduction i n
recovery time during the breathing of oxygen
concealed patients with a substantial response.
An attempt was made to predict such good
responders.
There was, however, no
relationship between initial arterial olqrgen
tension and the length of recovery as indicated
This test might be
by VA scale. (r = 0.28)
used to m a s u r e the benefit of short period
oxygen f o r chronic obstructive airways disease
and exercise induced dyspnoea.
163
VISUAL ANALOGUE SCALING OF EXERCISE
DYSPNOEA IN PATIENTS WITH CHRONIC LUNG DISEASE
J. W. REED, C. M. SPRAKE and J. E. COTES
Departments of Physiological Sciences
and Occupational iiealth & Hygiene,
The University, Newcastle upon m e . NE2 4AA.
The lower and upper limits of the lOOmm visual
analogue scale for breathlessness (VAS) are
usually set respectively at "not breathless"
and "extremely" or "very very breathless".
However, subjects differ in the proportion of
the scale which they use and this 16 a
complicating factor when making comparisons
between subjects (Aitken RCB, Proc Roy Soc Med
1968;62:989-93). Attdptlng to fix the upper
limit by teat exercise or breathing 1202 does not
fully overcame the difficulty, which in the
patients may be accentuated by their having a
personal standard of extreme breathlessness
during acute episodes of chest illness.
With a view to making comparisons between
eubjects VA8 scores were obtained at 1 min
intervals during progressive exercise up to the