Importance of Exercise With Cystic Fibrosis

Critically analyse how the physiological benefits of exercise contribute to an improvement in coping with the physical demands of everyday life in this client group and how it compares with traditional Physiotherapy Techniques (Postural Drainage and Percussion)

Cystic fibrosis is an inherited disease very common among Caucasians, but rare in Asians and Negroes. It is an autosomal recessive condition, with an estimated one in twenty of a Caucasian population heterozygous for the condition. The number of live births of children having cystic fibrosis is high; between 1 in 500 and 1in 3000 (P. Howard, 1991 p.137), or 1 in 2000 (P. McGowan, 20003 p.142, G.K. Crompton, 1987 p.289). In the UK a figure of 1 in 4000 is given (W.J.M/ Kinnear et al, 1999 p.52). Kinnear et al (p. 52) also suggest a reason for the extremely high number (1 in 20) of heterozygotes in the population, that perhaps this high number is the result of some selection advantage, in this case possibly providing some protection from severe secretory diarrhoea caused by for example cholera.

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A mutation in a single gene (called pf) causes a defect in a plasma membrane protein called cystic fibrosis transmembrane conductance regulator (CFTC). This gene is found on chromosome 7 (W.J.M. Kinnear et al, 1991 p. 52), and it is this gene that normally controls the movement of calcium ions. With it non-functional, calcium ions cannot pass through the membrane (P.H. Raven & G.B. Johnson, 2002 p.261). As with many other inherited disorders, the pf gene has pleiotropic effects, i.e. one gene has multiple effects, in this case overly sticky mucus, clogged blood vessels, salty sweat, pancreas and liver failure and many other symptoms (Raven & Johnson, 2002, p.253).

Sometimes the gene appears to have the correct amino acid sequence but the condition is still produced. This appears to be due to a defect in one of the chaperone proteins, proteins that enable the gene product to fold to its final form. With the chaperone protein defective this does not occur and so cystic fibrosis is still the result (P.H. Raven & GB Johnson, 2002 p.44). The table below shows (a) features of cystic fibrosis, (a) and (b) some complications arising from it.

(Definitions:cor pulmonale: disease of the heart characterised by hypertropy and dilation of the right ventricle and secondary disease of the lungs or their blood vessels.

Bronhiectasis: a chronic inflammatory or degenerative condition of one or more bronchi or bronchioles marked by dilation and loss of elasticity of the walls. Anon, 2006 in Medline Plus, Medical Dictionary)

Other complications can also occur, some these being given by P. McGowan (2003 p.142) as Meningitis, Metastatic abscess (e.g. in the brain, and Amyloid formation (e.g. in the kidney).

At present cystic fibrosis is always a fatal condition, death occurring either from the condition itself, or from one of its many complications. However the outlook for the patient, both in terms of life span and quality of life has continued to improve over the last few decades. Where once it was largely a disease of childhood with only about 5% reaching the age of 17, a 1987 publication estimates perhaps 25% surviving to age 20 (G.K. Crompton, 1987 p. 292). By 2003 though, the mean survival had risen to 29 years (P. McGowan, 2003. p.143).

There are several methods of treatment for cystic fibrosis, improvements in some of these being responsible for much of the improvement in outcome for patients seen today. These methods will be discussed, in particular the traditional physiotherapy methods of Postural Drainage and Percussion, and compared to the effect of exercise on the patient’s prognosis. But first a brief consideration of the effects of cystic fibrosis so that it is clear what the treatment is aiming to change.

Cystic Fibrosis: Signs and Symptoms

Cystic fibrosis is primarily a disease of the respiratory system, although various other parts of the body are also affected. It is caused by the gene mutation referred to in the introduction. There are up to 500 different mutations, but 3 main ones, which cause 90% of the cases (W.J.M. Kinnear et al, 1999, p.52). These adversely affect the exocrine glands and the mucus-secreting glands, resulting in excess mucus and difficulty in clearing it. All such glands are affected, thus its wide ranging effects on other organs apart from the lungs, e.g. the pancreas. The excess mucus production is difficult to remove, due to impaired ciliary action in the airways leading to repeat infections and bronchiectasis.

The disease is normally present at birth, although initially it may be asymptomatic or confused with other respiratory conditions such as asthma. Early signs of the disease are not always of a respiratory nature however, as some new-borns present with meconium ilius, while in some young children malabsorption and failure to thrive occur (W.J.M. Kinnear et al, 1999, p.52). Respiratory complications are however, the main feature, and generally present by age ten. Thick, viscid mucus is produced which is difficult to shift, and the bronchial obstruction it causes leads to infection. This leads to further obstruction as DNA from dead bacteria increases the viscosity and so produces a cycle of infection and increasing viscosity.

Coughs, occasional at first, become more frequent, eventually leading to bronchiectasis with persistant purulent sputum expectoration. There may be blood in the sputum (haemoptysis), wheezing and intestinal obstruction, and the patient may become breathless (P. Howard, 1991, p. 28). These conditions worsen, nutrition may be poor leading to stunted growth, and finger clubbing becomes common as bronchial infection takes hold, and finally, in the terminal stages there may be cyanosis and cor pulmonale

As can be seen from the aforementioned, cystic fibrosis is not a straightforward disease, and often, especially in babies and young children positive diagnosis can be difficult. Symptoms may be similar to other respiratory conditions, particularly in the early stages, plus secondary conditions may occur. These include infections such as with Staphylococcal pneumonia, this initial infection allowing further infections with other bacteria, particularly where broad spectrum antibiotics have been used so removing non-pathogens and allowing colonisation by drug resistant Staphylococci. If the patient survives to 16 or 17 years of age gastrointestinal problems may continue, but then respiratory disease tends to dominate, ending with cor pulmonale and/or respiratory failure (P. Howard, 1991, p138).

Because of the variety of symptoms and the difficulty sometimes of diagnosing cystic fibrosis, there is no one specific treatment, treatment being aimed at the removal of mucus secretions so aiding prevention and control of pulmonary symptoms (GK Crompton, 1987, p. 291). And this is the more effective the earlier in the disease process it is started. Thus a definite diagnosis as early as possible will lead to more effective treatment.

Various tests are carried out when cystic fibrosis is suspected. This may be because of a family history of the disease, failure of the child to grow at the expected rate, gastrointestinal problems or other respiratory problems such as asthma with which it may be confused. Pre-natal diagnosis may be carried out by amniocentesis or chorion-villous sampling if parents are known to be carriers of the condition. Otherwise various tests, e.g. the Guthrie test, the Immunoreactive trypsin test or most commonly the Sweat test (in which raised levels of sodium and chloride in the sweat are taken as a clear indication of the disease and is the most accurate test for this) are carried out. However the sweat test is not always so effective in adults.

Traditional Treatments: Postural Drainage and Percussion

Once the condition has been diagnosed treatment should be started immediately, even if the child has only minor symptoms or is asymptomatic. Treatment(s) may be based on any or all of the following: Physiotherapy, Antibiotics, DNase (to degrade the bacterial DNA that builds up in the airways, Anti-inflammatory drugs and nutritional support. It is the physiotherapy treatment that will now be considered.

The two traditional physiotherapy techniques that are used for Cystic Fibrosis patients are Postural Drainage and Percussion. As the name implies, the former technique centres around placing the patient in a particular posture to facilitate draining of excess mucus from the airways. It is used in the treatment of bronchiectasis and lung abscesses, and the patient is placed head downwards so that the trachea is down and below the affected area so allowing drainage to occur (Anon, 2006). The use of postural drainage has quite a long history, with the first reference to its use in 1901 by W. Ewart in the Lancet (L. Lannefors et al, 2004). Ewart suggested continuous drainage for hours, with the patient sleeping in the position if possible.

For postural drainage their are 12 positions, one for each lung unit, and once the patient is in the appropriate one percussion is applied (L.Lannefors et al, 2004). Percussion is a technique used to assess changes in the thorax or abdomen, and is carried out by tapping the surface to deduce the underlying structure. It is “done with the middle finger of the right hand tapping on the middle finger of the left hand, which is positioned with the whole palm on the body” (Anon, 2006). This can produce four different sounds, sonorous, hypersonorous, relatively dull sound, or completely dull sound, these indicating the structure below. For example a solid mass will produce a dull sound, while a hollow, air-containing structure will produce a sonorous sound.

No studies have been carried out on the effects of manual percussion, but it is thought that air trapped between the chest wall and the cupped hand produces a vibratory wave that loosens secretions attached to the airway walls. These two techniques are often used in conjunction, a problem with the postural draining being the time that the patient must lie in the appropriate position, an hour being suggested as the effective time. For babies and toddlers an hour in this position is only likely to be possible when they are asleep. For older patients compliance with the treatment may be difficult – how many children or teenagers can happily stay still in a particular position for up to an hour without boredom setting in?

But what of the actual effectiveness of these techniques? They have been used for a long time now often with modifications to the original method. There is much in the literature concerning these methods but including much that is conflicting, leaving the benefit of these treatments not always clear.

There are now many techniques for airway clearance including variations on the two in question, thus it is difficult to make a straight comparison between them all. SG Butler and RJ Sutherland (1998) looked at several airway clearance techniques and concluded that no one technique was shown superior to the others. But a long-term study comparing conventional postural drainage and percussion with the positive expiratory pressure (PEP) technique found PEP to be significantly better. One other study looking at several techniques concluded that there was no particular difference between them, but that all were better than no treatment (J Thomas & D Brooks, 1995).

More recent papers indicate a lesser use of postural drainage in its original form, for example BM Button et al, (2004), compared traditional postural drainage with a modified form and found that the latter resulted in less episodes of gastro-oesophageal reflux. Similarly a review of the physiotherapy management of hospitalised children (K Farbotko et al, 2005) revealed a significant decrease in the use of postural drainage, but an increase in the use of a modified postural drainage system, and positive expiratory pressure devices. Other methods showed no significant change in their use.

Another recent study (F Dennis & MJ Rosen, 2006) considered non pharmacological airway clearance therapies by reviewing many papers on the subject, and concluded that such therapies did increase airway clearance, but that their effect compared with the unassisted cough was unknown. Thus there are many studies but they are often not comparable, they assess different methods, do not always have large enough sample sizes to make statistical comparisons, and of course are using different groups of patients who may vary in many ways. For instance in age, sex, seriousness of their symptoms, or in compliance with the treatments. CM Oermann et al, (2000) found that it was the sicker patients who were more likely to be compliant, something that could skew results if not taken into account in further studies.

Benefits of Exercise

In recent years more emphasis has been placed on the use of exercise as a means of treating cystic fibrosis patients, and for these an improvement in aerobic capacity is particularly useful. Exercise has benefits for all, and changes in both anaerobic and aerobic systems can occur depending on the type of training undertaken. Improvements in anaerobic systems are of more use in preparing for short-lived events requiring power or speed, e.g. weight lifting or sprinting, while improvements in aerobic systems are needed for distance events. In patients whose respiratory systems are compromised as in cystic fibrosis there will often be a reduction in lung volume or distensibility, with a corresponding reduction in vital capacity, total lung capacity and also inspiratory muscle strength (M Estenne et al, 1993). For these patients aerobic exercise is likely to be useful.

Aerobic respiration causes various changes in the individuals’ metabolism and in the cardiovascular and respiratory systems. Some of these are listed below, the list being compiled from Exercise Physiology, by McArdale et al, (1996)

Metabolic Adaptations

• Mitochondria from trained skeletal muscle become larger and more numerous
• Increased capacity to generate ATP
• An increase in the trained muscles capacity to mobilise, deliver and oxidise lipids
• Increased carbohydrate metabolism
• Selective hypertrophy of fast and slow twitch muscle types depending on use

Cardiovascular and Respiratory Adaptations

• Heart size generally increases
• Increase in plasma volume
• Heart rate decreases as a result of aerobic training
• The heart’s stroke volume and cardiac output increases
• A significant increase in quantity of oxygen extracted from the blood
• Aerobic training causes a large increase in total muscle blood flow during maximal exercise
• Blood pressure is reduced both at rest and at sub-maximal exercise
• Psychological benefits.

A consideration of the above list indicates several changes of interest for the cystic fibrosis patient, for example the increase in oxygen extracted from the blood and an increase in the ability to oxidise lipids. And psychological changes produced by sport or any physical activity are important for both the healthy individual and the CF patient. It can reduce mild depression, aid in sleeping, and give confidence in ones physical abilities, all which will make the patient more confident in themselves and in their handling of their condition. Although exercise alone is not going to replace all other treatments, it has a definite place as one of them, especially in the earlier and milder stages of the disease.

An overview of treatment for cystic fibrosis (L Lannefors et al, 2004), describes the methods used at the Lund CF Centre in Sweden, starting in the 1980’s. There the treatment is tailored to each individual, with an emphasis on physical activity and absolutely no use of postural drainage or percussion (not used there since 1983). The treatment is started as soon as the condition is diagnosed and incorporates much physical activity. This is particularly important for babies or very young children, as they need to get used to someone applying physiotherapy. Left to the age of 3 or 4 years the child may not be very amenable to what to them is a boring and pointless activity, but started sooner is more likely to accept the treatment.

The activity part of the treatment is tailored for each individual with their input taken into account, and aims to keep air-ways as clear as possible using physical activity, and physical activity as therapy for adults with bronchiectasis has been described ( J Pryor, 2004). Although there appears to be little to back the approach considering the lack of rigorous clinical studies available, it does appear from accumulated clinical experience that patients benefit from it.

The paper by DM Orenstein et al, (2004) considers at length strength and aerobic training in children with cystic fibrosis, with many similar points made as in L Lannefors et al, (2004) overview of CF treatments. The introduction to this paper contains a brief review of many others, often showing similarities in results but not backed up by rigorous clinical studies. This study is the first fully randomised trial, measuring fitness, pulmonary function and quality of life, and was tested on a home based exercise programme. The CF patients were chosen according to pre-set criteria and randomly allocated to treatments. Thus the results could be analysed to check for any significant changes in outcomes.

Results for this study were not always as expected, particularly for the aerobic training group which showed no increase in measures of aerobic fitness over time. It did not produce any greater fitness or pulmonary function than strength training. However both groups showed significant increases in weight gain, of particular importance, as CF children are often underweight leading to increased morbidity and mortality. The trial did not always give the expected results, but as great care had been taken with the experimental design, at least the results could be properly quantified and analysed.

Conclusion

In conclusion, it would appear that work still needs to be done regarding appropriate experimental design, to fully understand the rationales for treatment, and to fully appreciate the effect of physical activity on aerobic capacity and disease progression. For as Orenstain et al comment:

“Exercise has the ability to improve the ability of a patient with Cystic Fibrosis to cope with the physical demands of everyday life” (Chest 2004, 126:1204-1214)

REFERENCES

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