Transcript Slide 1

The short-term, between-session reproducibility of
Sniff nasal pressure (SnPnas) in COPD patients;
Implications for baseline measurements prior
to rehabilitation programmes
Dimitra
1
Nikoletou ,
Gerard
2
Rafferty ,
Robert
1
Grant
and John
2
Moxham
School of Rehabilitation Sciences, Faculty of Health and Social Care Sciences, St George's, University of London/ Kingston University 1 and King’s College London 2
Introduction
Methods
Results
Rehabilitation programmes and research
studies often use respiratory muscle tests to
assess the effect of interventions, such as
inspiratory muscle training, on respiratory
muscle strength .1
Patients performed SnPnas, PImax and PEmax manoeuvres according to
ATS/ERS standards1, on 3 different sessions (S1, S2 and S3) at least 3
days apart. SnPnas was performed at functional residual capacity (FRC),
PImax at FRC and at residual volume (RV) to explore volume-dependent
differences in the learning effect and PEmax at total lung capacity (TLC). A
minimum of 10 attempts were made for each measure on each session,
with one minute break between attempts. The same investigator performed
all assessments.
•SnPnas had the lowest mean change between
sessions [mean (p value) S2-S1: 2.1 (0.4) and S3S2:-0.3 (0.9)] and gave the highest intra-class
correlation coefficient (ICC S2-S3:0.96)
Maximal inspiratory and expiratory pressures
(PImax and PEmax respectively), the most
commonly used tests, are non-invasive but
require at least 3 practice sessions in COPD
patients to minimise the learning effect and
obtain more accurate baseline values.2,3
Sniff nasal inspiratory pressure (SnPnas), has
been shown to complement PImax in the
assessment of inspiratory muscle strength1 and
to improve diagnosis of inspiratory muscle
weakness when the two tests are combined 4 .
In COPD patients, its reproducibility over repeat
sessions is currently unknown.
Tests
(cmH2O)
Twenty one patients (13M/8F) with moderate to
severe COPD [mean (SD) FEV1%pred:38%(15),
mean (SD) FEV1/FVC: 34.3 (10.4)].
All patients had definitive smoking history, were
free of exacerbations of COPD and had not
changed their medication for the last 4 weeks
prior to the study.
•When the best value out of 3 sessions was
considered, SnPnas values were 12% greater than
PImax (FRC) and 11% greater than PImax (RV).
Intra-class
Correlation
Coefficient
(ICC)
2
3
S2-S1
S3-S2
S2-S3
PImax/at FRC
58.6(12.8)
55(13.2)
56.2(15.6)
-3.6(0.2)
1.2(0.7)
0.82
PImax/at RV
57.6(11.7)
60(16.1)
58.9(13.5)
2.4(0.4)
-1.1(0.6)
0.89
SnPnas
65.7(15.7)
67.8(18.1)
67.5(20.3)
2.1(0.4)
-0.3(0.9)
0.96
PEmax
90.4(28.5)
91.7(28.8)
93(31.3)
1.3(0.7)
1.2(0.7)
0.93
Conclusions
Table 1: Group mean (SD) per session, differences in mean and intra-class correlation coefficient (ICC)
The between-session reproducibility of SnPnas is
better than that of PImax over short time intervals in
stable COPD patients. We recommend the inclusion
of this test in the last 2 practice sessions for PImax
and PEmax, prior to intervention studies or
rehabilitation programmes.
175
1.To assess the short-term, between-session
reproducibility of SnPnas in COPD patients.
Subjects
Differences
Mean(p value)
1
Aims of the study
References
150
125
cmH2O
2. To compare it with that of maximal inspiratory
and expiratory pressures (PImax and PEmax ).
Sessions
Mean(SD)
• SnPnas gave higher values than PImax on every
session, each time excluding presence of weakness.
1. ATS/ERS statement on respiratory muscle testing. Tests of respiratory
muscle strength. Am J Resp Crit Care Med 2002; 166 (4): 5528-547.
100
2. Morrison NJ, Richardson J, Dunn L et al. Respiratory muscle
performance in normal elderly subjects and patients with COPD. Chest
1989; 95: 90-94
75
50
3. Larson JL, Covey MK, Vitalo CA et al. Maximal inspiratory pressure;
learning effect and test-retest reliability in patients with chronic obstructive
pulmonary disease. Chest 1993; 104: 448-453.
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0
1
2
3
PImax at FRC
1
2
3
PImax at RV
1
2
SNIP
3
1
2
3
4. Steier J, Kaul S, Seymour J et al. The value of multiple tests of
respiratory muscle function. Thorax 2007; 62: 975-980.
PEmax
Fig 1: Group measurements in each session (1,2 and 3). The horizontal lines represent the group’s mean
value.
Acknowledgements:
All COPD patients from King’s College Hospital who participated in this study, Tom Collins, Clinical Scientist, Wandsworth Community Services, for poster design advice
Contact details
Dr Dimitra Nikoletou
Senior Lecturer, School of Rehabilitation Sciences
[email protected]
www.healthcare.ac.uk