Appraisal
The PEDro scale is used to evaluate and critically appraise studies, create a consistent quality of evidence score (appendix 1) and is design specific. There is no widely accepted or gold standard critical appraisal tool that’s applicable to all study designs (1). Therefore PEDro (2) was used as it has a fair-to-good reliability and validity (3). This essay will synthesise four studies (appendix 2) to answer the clinical question; how effective is water-based exercise in improving quality of life in patients with Chronic Obstructive Pulmonary Disease (COPD)?
Quality of Life
COPD impairs quality of life and can deteriorate significantly with increasing severity (4). Evidence from two high quality studies and two fair quality studies shows that water-based exercise significantly improves quality of life in patients with COPD, consistent with Lacasse et al. (5).
Chronic Respiratory Disease Questionnaire (CRDQ) and Hospital Anxiety and Depression (HAD) were used by one high and one fair quality study. The high quality randomised controlled trial (RCT) (6) showed significant improvements in CRDQ scores between groups, but no difference in anxiety. Whereas decreased CRDQ score and increased anxiety scores were evident in the fair quality study (7). Changes in CRDQ and HAD scores may be due to group therapy effect. St George’s Respiratory Questionnaire (SGDQ) scores improved in studies by Wadell et al. (8) and de Souto et al. (9). Short-form 36 improved physical health score to p<0.015 in the water group alone (8), but wasn’t used in the other three studies. Consistent outcome measures between studies allows for appropriate comparison, however it’s difficult to pool the results together as they used different questionnaires.
SGRQ and CRDQ have been validated and used extensively in clinical studies but are time consuming and have high drop out rates (10). Evidence suggests questionnaires may require specialist software, limiting their use in clinical practice. As an alternative, the COPD assessment test could be used in future practice. It measures the impact of COPD on an individual’s life, and how this changes over time (11). It has similar values to SGRQ with identical reliability and therefore may be favoured when time is limited (11).
Patients with COPD often have dyspnea and reduced exercise capacity, which can reduce quality of life (4). Dyspnea was significantly lower in water-based groups and improved pulmonary function/FEV1 in two high quality studies (6,8), measured using the Borg Scale. Similar results were found in one fair quality study (9), but assessed using Medical Research Council scale (MRC). However MRC and the Borg Scale are easily comparable (reference). Conversely ÖZDEMİR et al. (7) found no difference pre- and post-study. Despite using different scales, results are comparable and water-based exercise improves dyspnea and pulmonary function.
Quality of life and exercise capacity were measured using the incremental shuttle walking test (ISWT), endurance shuttle walk test (ESWT) and 6-minute walk test (6MWT). Overall, three out of the four studies showed significant improvements in their distance, suggesting water-based exercise improves physical outcomes and therefore quality of life in patients with COPD. However ÖZDEMİR et al. (7) found no significant improvements. No change in dyspnea, pulmonary function, and absence of lower body exercise may explain why 6MWT didn’t improve. However, not all four studies included all of these outcome measures in their design.
Volume of Exercise
Pulmonary rehabilitation (PR) is a training programme consisting of gym-based exercises twice a week for 8-12 weeks (12). Evidence suggests longer participation has better long-term effects, and exercising at 60-80% of maximal heart rate (HR) is most effective in COPD (12). One study (8) reported to be lead by a physiotherapist, and another (7) reported to be lead by a physiotherapist and a chest physician. It is unclear who should lead future sessions as not all the studies reported the session leader.
Duration
Sessions varied from 35-90 minutes for 4-12 weeks. All four studies consistently exercised three times a week and three studies (6,8,9) showed significant improvements. Participants made greater improvements when exercising for 45-90 minutes whereas ÖZDEMİR et al. (7) exercised for 35 minutes, 3 times a week for 4 weeks and showed no significant improvements. The short duration of the programme limited improvements. De Souto et al. (9) experienced a high drop out rate from the water group which suggests there may be motivational issues as a 90 minute session was too long. Therefore, clinicians need to consider participant preferences and this review recommends exercising for 45 minutes, 3 times a week, for 8 weeks minimum. This is consistent with recommendations in the systematic review by Shead et al. (13).
Type
Whole body exercises were completed by three studies (6,8,9), showing significant improvements, but only a maximum of 12 participants could complete the exercise per session in the high quality study by McNamara et al. (6). This increases the amount of sessions provided, increasing the cost and a clinician will see fewer patients. However, this study had the greatest compliance for both groups, suggesting that patients preferred full body exercises compared to the other studies.
Whereas ÖZDEMİR et al. (7) only performed upper-body resistance exercises. This may be a reason why outcome measures such as 6MWT and dyspnea scores didn’t improve. Additionally, floatation devices were used which were not used in the other three studies, a further explanation why results were less signicant. Upper-body exercises can be perceived as fatiguing and many individuals dislike performing exercises that cause fatigue (14). Therefore this review suggests that whole body endurance exercises have a greater benefit to patients with COPD when exercising in water.
Intensity
It is difficult to compare session intensity as all four studies used a different method of measurement. High quality evidence from two studies (6,8) and one fair quality study (9) exercised at an intensity of 5 on the Borg Scale. However one study didn’t report the intensity of the sessions. As a result, inconsistencies between sessions could limit significant improvements made in the water-based exercise group. Therefore clinicians need to consider HR monitoring, used in a high quality study (8). HR and core temperature increase when exercising in hot temperatures as heat loss mechanisms become less efficient. Therefore exercise intensity will be overestimated compared to normal temperatures (15). Evidence suggests rate of perceived exertion (RPE) can be a cost-effective, valid and reliable alternative to HR for monitoring exercise intensity (16). An RPE score above 4 is considered to be working above 60% of maximum HR. However RPE is subjective and often underestimated by individuals, with poor test-retest reliability of the RPE scale (17). This method would not require expensive equipment and may be very useful and practical for clinicians during water-based exercises.
McNamara et al. (18) stated that water immersion may influence diaphragm function. Due to poor reporting it’s inconclusive whether depth of water immersion affected diaphragm and breathing mechanics. Those that did report it asked participants to submerge between the xiphoid sternum and the clavicle (6) and similarly a fair quality study (7) immersed participants to xiphoid level. Respiratory muscle strength was also reported by this high quality RCT (6), resulting in significant improvements but wasn’t reported by the other studies. RCT’s have been shown to provide the gold standard and most reliable data for demonstrating efficacy of treatment effects and to prevents errors and bias occurring (13). Therefore immersion at the xiphoid level is recommended for practice.
All four studies reported swimming pool temperatures between 30-34°C, showing significant improvements in water-based exercise for COPD. McNamara et al. (6) also reported air temperature and humidity, a potential contributing factor that was not reported in the other studies. This high quality RCT also had a confidence interval of 95%, showing that if the statistical analysis were repeated, the values would contain the true mean for the population with 95% confidence. Whereas the other three studies failed to state confidence intervals, showing poor reporting. Therefore for practice it’s suggested the optimal pool temperature should be 30-34°C, supported by recommendations from Shead et al. (13).
COPD Severity
GOLD Criteria is used to classify patients with COPD as mild, moderate, severe or very severe (20). Participants in the study by McNamara et al. (6) had a confirmed COPD diagnosis in a stable phase with the presence of one or more physical comorbidities. Participants with moderate to severe COPD were used in three studies (7–9). It would be suggested that patients with moderate to severe COPD were provided with the opportunity for water-based exercise. However there was no comparison between patients with different COPD classification. Participants with a COPD diagnosis were recruited for a high quality study (6) and is unclear as the progression of the disease in these patients, and suggests that we cannot be certain if water-based exercise would have the same effect on these types of patients. However all four studies used large sample sizes which allows results to be applicable to the specific population.
Additionally two of the four studies didn’t state participant gender, and research from one fair quality study (7) only used male participants and a high quality study (8) used 27 females and 16 males. Therefore we cannot assume that both genders reacted the same or differently. Participant age differed between all four studies, with two studies failing to report their age. De Souto et al. (9) used participants aged 40 and showed significant improvements, however a lower age could lower the threshold of lung damage when compared to participants aged 72 ± 9 years used in McNamara et al. (6) study. This age group could be evident as to why 8 participants dropped out.
Research suggests that due to hyperinflation caused by COPD, the surface are of the diaphragm in patients with moderate to severe COPD is reduced, changing the diaphragm mechanics, causing exacerbations (18). McNamara et al. (6) experienced 0 exacerbations in the water-based exercise group compared to 3 in the control group. However in the study by Wadell et al. (8), participants in the water group had a higher exacerbation rate and more frequent antibiotic use. Greater volume and duration of session compared to the other three studies may have caused this effect, but it can be questioned whether infection risk increases when all participants are in the pool together. The two other studies failed to report any exacerbations.
Conclusion
Recommendations for practice comply with suggestions by Shead et al. (13) and water-based exercise can be used as an alternative exercise to PR. It has physiological and psychological benefits of group exercise and improves quality of life in COPD patients.
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