Hi
I am in the process
or revamping my Lung Function test Policy and Procedure and have a couple of
questions
Can anyone
confirm:
1.
Should
we or should we not test VC?
2.
Does
anyone have any figures, scoring system or percentages that they use as
criteria for repeat testing or referral criteria?
Please see but excuse
my ramble below.
Point 1:
Should we record the VC in an Occupational Health Nurse
setting?
When I initially undertook
spirometry training (circa 1990) we used to ask our patients to undertake 3
relaxed (VC) and then 3 forced (FVC) tests on the manual Vitalograph
spirormeter. With the introduction of the newer electronic spirometer’s
I have continued this practice, however a colleague recently attended a course
and was informed that there was no longer a requirement to undertake the
relaxed (VC) test. However I am reluctant to drop this test from
my procedure or policy without some medical endorsements, thus I seek your
opinion please?
I have looked at the following
documents for guidance:
·
The HSE MS 25 Guidance simply
states the testing of FEV1 and FVC as a
minimum;
·
In the European Respiratory
Journal 2005; 26: 511-522 - Standardisation of the measurement of lung
volumes. I can find definitions of VC, namely IVC and EVC, but nothing
in the way of relevance of this test in preliminary occupational health
surveillance setting;
·
In the European Respiratory
Journal 2005; 26: 948 - 968 - Interpretative strategies for lung function
tests. It states that “an obstructive ventilatory defect is a
disproportionate reduction of maximal air flow in relation to the maximal
volume (i.e. VC). It implies airway narrowing during exhalation and is
defined by a reduced FEV1/VC ratio.” This document later says
that VC, FEV1, FEV1/VC ratio and TLC (total lung capacity not used
in the OH setting?), are the basic parameters used to properly interpret lung
function, although FVC is often used in place of
VC;
·
In the European Respiratory J
2005; 26: 319 – Standardisation of spirometry. It states that the FVC
and FEV1 are the most important aspects of spirometry, yet later it adds that
in some patients, a slow VC or IVC may provide a larger and more appropriate
denominator for calculation of the FEV1/VC%.
The latter document later
discusses the VC manoeuvre and I can clarify that I have always undertaken the
EVC as opposed to the IVC test. In our policy we predominantly use the
VC, FVC, FEV1 and FEV1 ratio, but we also record and
look at the FMF25-75 and PEF.
As I understood it the VC and FVC
results should be similar, however if the FVC was less than the VC by more
that 200mls it may indicate a lower airway collapse often seen in obstructive
airway disease. I have therefore always tested the VC, always
undertaking this test first to help familiarise the patients with the
procedure, I also understood that forced spirometry could cause respiratory
muscle fatigue causing inaccurate recordings of the VC if undertaken post
forced spirometry?
Point 2:
I am looking for some guidance on repeat testing and referral
criteria.
In our current policy we repeat
the test again within one month if the results are “down on last test” but no
amount of deterioration is given. We also refer our patients onto either
an OH Physician or Dr P Cullinan at the Royal Brompton Hospital
depending upon their history if there is a “significant downward trend, or
there is signs of a combined, restrictive or obstructive disease pattern
shown.”
Is there any guidance or figures
you would suggest that I use for these deterioration categories so that I can
make my policy and procedure
auditable?
I have always worked with the fact
that:
·
VC, FVC and FEV1, FVC should
be greater than 80% of their predicted normal values, and
·
FEV1 ratio and
FMF25-75 should be greater than 70% of their predicted normal
value.
One of my colleagues seems to
recall being told that 5% deterioration on these predicted percentages was the
referable criteria.
In the European Respiratory J
2005; 26: 948 - 968 - Interpretative strategies for lung function tests.
It references and quotes numerous severity scores, the severity table given
only looks at FEV1 and starts as mild in severity if the %
predicted is less than 70 and very severe if the % predicted percent is less
than 35, which does not relate to OH referral
criteria.
I therefore wondered if you
were aware of any scoring criteria that could or should be applied in the
occupational health setting to make my policy more
auditable.
May I take this
opportunity to thank you all for any help and guidance you may be able to
give?
Yours sincerely
Janet
Elliot. MSc.
CMIOSH. OHND. RGN.
Occupational Health
Adviser
Corazon Health
Limited
5 - 6
The Mill
Copley Hill Business Park
Cambridge
Road, Cambridge
CB22
3GN
Switchboard:
01223 834404
Fax:
01223
834412
Web:
www.corazonhealth.co.uk
Corazon Health
Limited is registered in England and Wales; company
number 4434615
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