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Warwick
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Charity Reg No: 1048816
Company Reg No: 3090774

Chairman: Dr Jonathan Shapiro
MA (Cantab), MB, ChB, MRCGP

FAQs - Clinical | FAQs - General

 

QUESTION:
How do we choose a spirometer for the clinic?

ANSWER:
There are several things that you need to consider when purchasing a spirometer:

1. Consider where you are going to use it:
If you are going to need one that is moved from room to room or site to site you will need one that is small, portable and robust. The MicroMedical Microlab comes in a carrying case and fits the bill for this.
2. You will need a machine that gives you:
a) a hard copy print-out of the results and a volume time trace and flow volume trace.
Some spirometers will connect to a computer and down-load the results and the traces directly into the patient's records. This can be particularly helpful as traces and results are then easy to e-mail for quality control or validation by your local lung function lab. Alternatively, if you are paperless, traces can be scanned into the record.
b) a real-time visual display of the blow so that you can check that the patient has produced a good quality effort.
Some hand-held spirometers can be hooked up to a computer VDU to overcome this problem. If they don't then there are serious difficulties in ensuring that the blow is technically acceptable and valid. Poorly performed spirometry is useless and misleading.
3. You will need to be able to check the calibration of the equipment:
This usually means that you will need to purchase a calibration syringe. Some spirometers, such as those with turbine flow heads or ultra-sonic detectors, are robust and maintain calibration. For these you may be able to get away with a "physiological" calibration - i.e. you get someone who has no lung disease and whose lung function you know to do a test blow to check that the machine is recording correctly.
4. Consider the technical support, back-up and training you will receive:
You must be trained to use a spirometer properly and you need to ensure that there is someone in the practice who is competent at interpreting the results. I personally, would not recommend purchasing a spirometer through a medical wholesaler. They will not be able to give you the back up you need. I think you would be better advised to purchase one direct from a manufacturer such as Vitalograph, MicroMedical, Ferraris and Clement Clarke. Ask them what support and training they can give.

As a general rule, a spirometer that fits these criteria will cost around £1,200-£1,500. Clearly this is a not inconsiderable investment for your practice, so it would be wise to also consider who will use it and how often. I fear there are many spirometers that languish in cupboards and are not used because staff either do not have time or are not confident in its use. This is clearly a waste of resources.

A useful source of more detailed information is a recent article in Professional Nurse:
Gibbons D (2005) A comprehensive guide to buying a spirometer.
Professional Nurse 20 (5) 45-48

You may also be interested in our training courses. We run a one-day short course in practical spirometry and basic spirometry interpretation and a NEW diploma level module; Spirometry for Practice. You can find further information and course dates on our website.

Please do not hesitate to contact us again if you need any further advice and assistance.

QUESTION:
Should I tell people to increase their inhaled steroids when they experience an exacerbation of their asthma?

ANSWER:
Increasing inhaled steroids:

Doubling up inhaled steroids in the short term has been advocated as good practice for some time. Experienced clinicians suggest that people with asthma should increase their steroids when they feel an exacerbation approaching, which may be before the peak flow drops.

The problem is that the BTS/SIGN Guideline is based on research evidence only, and there is not sufficient good quality research of 'the real world' to validate the doubling up. Reference to it is made in section 4.7.1 - onset of exacerbation of asthma - when only 5 fold increase is specifically mentioned. The paper that threw up some questions about doubling up was published in 1998 [ Garrett,J., Williams, S., Wong, C. and Holdway, D. (1998) Treatment of acute asthmatic exacerbations with an increased dose of inhaled steroid. Archives of Diseases of Childhood 79: 12 - 17], which suggested that the measure was ineffective. However, this was a small study - 28 children - and the steroids were only increased when the asthma was already worse, not at the first symptoms of a cold. Interestingly, the extensive research that shows that action plans are effective in reducing hospital admissions etc must incorporate the doubling up of inhaled steroids, but it would be difficult to tease this factor out.

There is also NOT the evidence to rule out doubling up during an exacerbation, and one could argue that adding in LABA in an exacerbation is risky, because it might mask worsening symptoms. ICS would be needed to reduce the inflammation, and their inclusion in an action plan at least ensures that those who have stopped using their preventer realize the importance of steroids in an exacerbation.

The bottom line is that experienced clinicians are still using doubling up as part of individualised asthma action plans, and we await the research that supports our clinical experience!

QUESTION:
Are large volume spacers better than the smaller spacers?

ANSWER:
There is a paper that shows significant differences in the amount of drug available for inhalation through different spacers:


Barry P, O’Callaghan C (1996) Inhalational drug delivery from seven different spacer devices. Thorax 51, 835-840

When compared with MDI alone the amount of sodium cromoglycate particles < 5micron recovered from spacers was:
118% from Fisonair, 124% from Nebuhaler and 36% from Aerochamber.
The amount of salbutamol recovered from a Volumatic was increased by 117% of that from an MDI. The aerochamber decreased the amount by 50%.
What we would point out about this study is that it was in vitro and was not a study of clinical efficacy.

In contrast a study in children (4-8 years) of the clinical efficacy of salbutamol found no difference in clinical effeicacy between the metal Nebuchamber, the Aerochamber or the Volumatic
Dompling E, Oudesluys-Murphy AM, Janssens HM et al (2001) Randomised controlled study of the clinical efficacy of spacer therapy in asthma with regard to electrostatic charge. Archives of Disease in Childhood 84, 178-182.

Where there is a lack of evidence for small volume spacers is in the reduction of inhaled steroid side effects. We do not know of any evidence that shows similar efficacy in this respect. We think you have a good argument for large volume spacers for use with inhaled steroids (and we know of several paediatricians who would support that argument). Arguing for large volume spacers for bronchodilators is more difficult. There is evidence for the efficacy of the Aerochamber in this respect.

Also, if a small volume spacer can be carried around more easily and is used rather than left at home then you could argue that it is more effective than a large volume spacer that the patient will not use.

QUESTION:
Should reversibility testing be used for diagnosis on every occasion?

ANSWER:
Some reflections on the current situation on using reversibility for diagnosis in COPD:

This is causing a great deal of confusion and controversy at the moment as there is discrepancy between the BTS & SIGN asthma guideline and the NICE COPD guideline.

The BTS & SIGN asthma guideline 2003 states that a 15% and 200ml improvement in the FEV1 is a positive reversibility test result in asthma. Revised BTS & SIGN guidelines were published on the 20th April this year (available from the BTS website www.brit-thoracic.org.uk) and the guidance about what constitutes a positive test have not changed. They still state that a diagnostic test of reversibility is a 15% and 200ml improvement in the FEV1. So the information that Lindsay has in her pack is correct and is in line with current BTS & SIGN guidance. We appreciate that this is in conflict with the recently published NICE COPD guideline. This talks about a 400ml improvement in the FEV1 suggesting asthma rather than COPD.

The key to the diagnosis of both asthma and COPD is the clinical history. If the history suggests asthma then a 15% and 200ml improvement on reversibility testing is sufficient to objectively support the clinical diagnosis of asthma.

In contrast, where the history suggests COPD and the spirometry is obstructed, then an improvement of less than 400ml FEV1 would support a diagnosis of COPD.

The NICE COPD guideline does not recommend routine reversibility testing for a variety of reasons:

  • The FEV1 tends to be a continuous variable in moderate to severe COPD
  • The magnitude of change in FEV1 cited as significant was not based on any evidence and was somewhat arbitrary
  • Bronchodilator response varies from day to day in the same individual. On previously cited levels of significance it was perfectly possible for a patient to have a positive test on one day and a negative on another
  • Reversibility testing cannot be used to predict long-term response to therapy and is therefore not helpful in selecting long-term treatment.

NICE suggest that, in the majority of cases a provisional diagnosis of COPD can be made on the history and the presence of airflow obstruction on spirometry. The patient can then be given a therapeutic trial of regular bronchodilators. It is important to review response to treatment after a few weeks (4-6 weeks would be reasonable). If there is a dramatic improvement in symptoms and/or FEV1 then this would call the provisional diagnosis of COPD into question.

The role of reversibility testing (and serial PEF) is to identify asthma in those cases where there is diagnostic doubt. If reversibility testing does not clarify the issue then consideration should be given to referring the patient for more exhaustive testing such as CT scanning or gas transfer.

The full length NICE guideline contains all the evidence for this recommendation. It is available on the NICE website (www.nice.org.uk/pdf/CG012_niceguideline.pdf). It is also published as a supplement to Thorax in March 2004.

The other problem is that the NICE guideline is in direct conflict with GMS COPD quality outcome framework. High level discussions are taking place at the Department of Health to resolve this, but until such time as the GMS outcome framework for COPD is revised you will be rewarded for carrying out reversibility tests. This is time consuming and the evidence suggests that it is not helpful, so a possible way of overcoming this conflict is:

  • Make a clinical diagnosis of COPD on the history and spirometry
  • Start the patient on a trial of therapy
  • Review after 4-6 weeks for repeat spirometry and assessment of response to therapy in terms of symptomatic improvement
  • If the spirometry improves by less than 400ml FEV1 this will support a diagnosis of COPD and can be termed a reversibility test for GMS. It will also have the advantage of ensuring that cases of asthma are not missed
  • If the lung function has returned to normal, or the FEV1 has increased by 400ml or more, or the patient reports a dramatic improvement in their symptoms then the diagnosis of COPD should be questioned. Such a response makes asthma the more likely diagnosis.

There will be some patients who have long-standing asthma and have developed a degree of fixed airflow obstruction. Their lung function will never return to normal and by looking at the spirometry and reversibility alone they will look like COPD patients. But they have asthma and will need to be treated along asthma guidelines. They key to managing these patients is the clinical history. I would suggest that, where there are patients with mixed disease it is safer to put them on the asthma register, treat them along asthma guidelines but expect COPD outcomes for the therapy.

QUESTION:
Should Volumatic spacers be washed and left to dry, even when they are used for high doses?

ANSWER:
Wash Volumatic Spacers prior to use:

Plastic spacers need to be washed initially, ie when new due to reduce high levels of initial static charge. (Clark & Lipworth 1996). This applies to when giving high dose bronchodilators as well. It is not an issue if spacers are stored dry or stored for a long time but they should not be put away wet. The risk of cross infection is minimal and we know of no published research on this issue.

Essentially, Volumatics if prescribed are single patient items. In reality we know this does not happen and we would certainly not avoid giving high doses of beta 2 in an emergency just because a new spacer was not available! Masks should be washed regularly. Ideally we should use a new mask for each patient but again there are practical and cost issues too!

The manufacturer’s patient information leaflet for Volumatics is not up to date with current clinical evidence and practice re washing and drip drying. One of the problems is that this information had to be produced for it to obtain a product licence. The manufacturers are unlikely to go through this process again once they have a product licence. However we do think it is confusing for patients when we say one thing and the patient information leaflet says something different.

Anti static effects last 3-4 weeks once a spacer has been soaked for a short while and then drip dried. Pierart F et al (1999) describe a study looking at reducing electrostatic charge by washing them in household detergent. Lung deposition of salbutamol via a spacer was 45.6% for a detergent coated spacer v 11.5% for a non detergent coated spacer and was highly significant.

Washing a spacer is also described in MIMS in the section on respiratory appliances.

QUESTION:
What advice can you give for use of beta blockade in patients with airflow obstruction?

ANSWER:
Advice is at present conflicting:

There is very clear evidence for the benefits of beta blockers for patients with hypertension, angina, myocardial infarction, congestive heart failure and cardiac arrhythmias and there are many patients who have both cardiovascular and airways disease. Despite clear evidence of their effectiveness in reducing mortality some clinicians have been reluctant to prescribe beta blockers for fear of inducing bronchoconstriction. To make matters worse The British National Formulary also cautions prescribers against their use in patients with obstructive airways disease.

A meta-analysis and a systematic review (both by the same authors) challenges this advice. Both studies concluded that cardioselective beta blockers do not significantly reduce airway function or cause adverse respiratory events. However, the studies analysed were small and of short duration and this is acknowledged by the authors. Further long-term studies are warranted, but these studies do suggest there is little evidence that these drugs should be withheld, provided that cardioselective drugs are used with caution. Cardioselective beta blockers have 20 times greater affinity for beta1 receptors than non-selective agents and should pose much less risk for bronchoconstriction. The available evidence suggests that the benefits generally outweigh the risks.

The references that you may like to look at are:

  • Saltpeter SS, Ormiston T, Saltpeter E, Poole P. Cates C (2002). Cardioselective beta-blockers for chronic obstructive pulmonary disease. Cochrane Database of Systematic Reviews 2002(2): CD003566
  • Saltpeter SR, Ormiston T, Saltpeter -blockers in patients with reactive airways disease: bEE (2002). Cardioselective a meta-analysis. Annals of Internal Medicine 137, 715-725
  • van der Woude HJ, Zaagsma J, Postma DS, Winter TH, van Hulst M, Aalbers R (2005). Detrimental effects of beta-blockers in COPD: a concern for nonselective beta-blockers. Chest 127(3), 818-824.

QUESTION:
I have been told there are some recommendations about caring for inhaler devices.  What are they and how can I get hold of a copy?

ANSWER:
You must be referring to the statement published by the Standards of Care Committee of the British Thoracic Society called 'Practical recommendations for the use of placebo inhaler devices, peak flow meters and inspiratory flow meters in clinical practice':

Education for Health (formerly NRTC) were commissioned by the Standards of Care Committee of the British Thoracic Society to review the literature and produce recommendations on the use of placebo devices in clinical practice, taking account of the issues around infection control.  We have taken a practical approach in an attempt to improve practice and raise standards, noting the importance of correct delivery of inhaled therapies and the current recommendations in different clinical guidelines.

This statement should be read in conjunction with the supporting document from the BTS Standards of Care Committee called: Practical recommendations for the use of placebo inhaler devices, peak flow meters and inspiratory flow meters in clinical practice. Both these documents can be downloaded here: