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The Short-term Effect of a Rollator on Functional Exercise Capacity Among Individuals With Severe COPD^*

^* From the Graduate Department of Rehabilitation Science (Ms. Solway) and the Department of Physical Therapy (Dr. Brooks), University of Toronto, Toronto, ON, Canada; and West Park Healthcare Center (Dr. Goldstein and Mr. Lau), Toronto, ON, Canada.

Correspondence to: Sherra Solway, MSc, BSc (PT), c/o Dr. Dina Brooks, Department of Physical Therapy, University of Toronto, 256 McCaul St, Toronto, ON, M5T 1W5, Canada; e-mail: s.solway{at}utoronto.ca

	Abstract

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

 
Study objectives: This study was conducted to examine the short-term effects of using a rollator on functional exercise capacity among individuals with COPD and to characterize which individuals benefit most from its use.

Design: Repeated-measures randomized crossover design using the 6-min walk test (6MWT) as the primary outcome measure.

Setting: Respiratory rehabilitation center.

Patients: Forty stable subjects who had received a diagnosis of COPD.

Interventions: Two 6MWTs were performed on each study day. One 6MWT was performed unaided, and the other was performed with a rollator. The order was randomized on the first day and reversed on the second day.

Results: Use of the rollator was associated with a significant reduction in dyspnea (p < 0.001) and duration of rest (reduction for the total group, 19 s; and reduction for those who walked < 300 m unaided, 40 s; p = 0.001) during the 6MWT. For subjects who walked < 300 m unaided, there was also a significant improvement in distance walked (p = 0.02). No changes were found for the measures of cardiorespiratory function or gait (p > 0.05). The requirement to rest during an unaided 6MWT was a significant predictor of improved functional exercise capacity with the use of the rollator (p < 0.005). The majority of subjects whose unaided 6MWT distance was < 300 m preferred using the rollator to walking unaided.

Conclusions: Use of a rollator was effective in improving functional exercise capacity by reducing dyspnea and rest duration among stable individuals with severe COPD. Individuals who walked < 300 m and individuals who required a rest during an unaided 6MWT benefited the most from using a rollator in terms of reduced dyspnea, reduced rest time, and improved distance walked.

Key Words: COPD • dyspnea • functional exercise capacity • rehabilitation • rollator • walk test

	Introduction

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

 
Individuals with COPD experience reduced functional exercise capacity as their condition progresses. In patients with severe disease, dyspnea may become so disabling that they are obliged to adopt a sedentary lifestyle. This results in further deconditioning, worsening of symptoms, and reduced quality of life.¹ Respiratory rehabilitation programs reverse this cycle by encouraging walking, which is an important, useful, and preferred form of exercise for many individuals with COPD.^{2 3}

Wheeled walking aids are sometimes prescribed for patients with COPD to improve their functional exercise capacity.⁴ Wheeled walkers are walker frames with two, three, or four standard wheels. While a rollator is also considered a walker with four wheels, the front two wheels typically are on swivel casters for easy maneuverability.⁵ Rollators also are equipped with hand brakes, a basket for carrying objects, and a fold-down seat that allows the user to rest at any time. Although wheeled walkers offer important advantages over standard walkers (ie, those without wheels),^{6 7 8 9} the effect of wheeled walkers on functional capacity and activities of daily living has not been studied extensively.

Information on the influence of wheeled walking aids in patients with COPD has been limited to reports that used small sample sizes,^{4 10 11 12 13 14} subjects with mild disease,¹⁴ testing that predated the use of standardized, validated walking tests,^{10 11} and a study design that was confounded by subjects having to pull their portable oxygen during the unassisted walk.⁴ Therefore, this study was undertaken to determine the short-term effect of using a rollator on functional exercise capacity among individuals with COPD and to characterize which individuals with COPD would benefit most from its use.

	Materials and Methods

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

 
Subjects
We recruited subjects who were enrolled in the respiratory rehabilitation program at West Park Healthcare Center (Toronto, ON, Canada). Subjects were considered eligible for the study if they had received a diagnosis of COPD,¹⁵ were clinically stable (ie, had no evidence of acute exacerbation and had experienced no change in medication or bronchodilator use in the previous 4 weeks), were between 55 and 85 years of age, and were unaccustomed to the use of a walking aid. Exclusion criteria included the presence of associated medical conditions that limited exercise tolerance (eg, symptomatic cardiovascular or musculoskeletal conditions and recent surgery) or an inability to communicate in English.

Protocol
The study was approved by the Human Subjects Review Committee (University of Toronto). All subjects gave informed written consent. A randomized crossover design was used with the 6-min walk test (6MWT) as the primary outcome measure. Each subject was studied at the same time of the day on two separate days in the same week. Subjects did not perform the exercise-training component of their respiratory rehabilitation program on study days and were requested to abstain from caffeine for 4 h prior to each session and to administer their inhaled bronchodilator 30 min before each session. Subjects wore the same footwear on both study days.

On each study day, two 6MWTs were performed with a minimum 1-h rest between tests. One 6MWT was performed unaided, and the other was performed using a rollator (Opal Legacy; Dolmite; Markham, ON, Canada). The test order was randomized (random numbers table) for the first day and reversed on the second day. The same rollator was used for all subjects (Fig 1 ). The height was adjusted to ensure that the handle bars were at the level of the subject’s ulnar styloid process,¹⁶ and this was kept consistent for both study days.

View larger version (74K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Photograph of the type of rollator (Opal Legacy; Dolmite) that was used for study. Reprinted with permission of BMedical.com (http://www.bmedical.com/e/walkers/dolomite/dolomite_legacy.asp).

Measures
Primary Measures:
Functional exercise capacity was the primary outcome of this study and was evaluated by 6MWT distance, duration of rest, and modified Borg ratings of dyspnea.^{20 21} Distance walked was automatically recorded using a photosensing device (Photoelectric Switch; Omron Corporation; Tokyo, Japan), which was placed on the wheel of the tester’s cart.

Secondary Measures:
Secondary measures were those of cardiorespiratory function and gait. Cardiorespiratory function included oxygen saturation and heart rate, which were acquired continuously with a finger probe pulse oximeter (Biox 3700; Ohmeda; Madison, WI). Respiratory rate, minute volume, and the phase relationships between the rib cage and abdominal excursions^{22 23} were monitored using a respiratory inductance plethysmograph (Respitrace; Ambulatory Monitoring, Inc; Ardsley, NY). This method has been validated during both treadmill and cycle ergometer exercise.^{23 24 25} The rib cage band was placed just under the axilla, and the abdominal band was placed below the lowest vertebral rib, just above the iliac crest.^{26 27 28} The bands were placed directly on the subject’s skin, as recommended by the manufacturer, and were secured by surgical tape.²⁹ The electronic oscillator unit then was taped to the chest wall to eliminate artifacts caused by movement of the unit.^{25 28} The plethysmograph was calibrated before each 6MWT with a volume spirometer (Spiroflow; PK Morgan Ltd; Rainham, Gillingham, UK).

Gait was evaluated by stride length using a self-developed stride counter, and overall walking speed was calculated by dividing the distance walked in 6 min by the duration of actual walking time (ie, the duration of rest was subtracted from the 6 min).

Other:
Demographic, descriptive data and recent spirometry results were extracted from each subject’s medical chart. Subjects completed the St. George’s Respiratory Disease Questionnaire (SGRDQ) during the study week and a standardized preference questionnaire on completion of the study. In the preference questionnaire, subjects were asked to identify their preference for walking during the 6MWT either with or without the rollator and their reasons for this preference. Weight-bearing by the upper extremities while using the rollator was measured by four strain gauges (LY Series Uniaxial Gauge; Omega Engineering Inc; Laval, QC, Canada) mounted on two force-measuring aluminum beams that were placed under the handle bars.

Data Acquisition
Signals from the respiratory inductance plethysmograph, volume spirometer, distance sensor, pulse oximeter, upper extremity weight-bearing sensors, and stride counter were sampled at 100 Hz using a laptop computer (Satellite Pro 410CS; Toshiba; Tokyo, Japan) with a data acquisition card (DAQCard-AI-16XE-50; National Instruments; Austin, TX) and data acquisition and processing software (LabVIEW, version 5.1; National Instruments).

Statistical Analysis
A sample size estimation using a two-tailed test with a type 1 error of 0.05 and power of 90% determined that a clinically significant difference in 6MWT distance (mean, 54 m³⁰ ) would be detected with a minimum of 16 subjects (SD, 86 m). However, to allow for the potential of using multiple linear regression with at least three variables, a sample size of 40 was sought. This estimation was based on the method of Norman and Streiner³¹ in which the recommended sample size is 5 to 10 times the number of variables included in the regression equation.

Data were analyzed for the total sample and for the subgroup of subjects with greater disability who walked < 300 m unaided.^{4 32} Variables were described for the total 6MWT, as well as for individual minutes of each 6MWT. Means, SDs, and SEs were calculated for all measures. Descriptive statistics also were used for age, height, weight, FEV₁, health-related quality of life, subject preference, and upper extremity weight-bearing. Differences in outcomes for the 6MWTs conducted with and without the rollator and for study day were analyzed using a two-way repeated-measures analysis of variance.

Univariate regression was used to explore the relationship between change in functional exercise capacity (ie, distance walked or perception of dyspnea) with the rollator and independent variables such as age, FEV₁, use of supplemental oxygen, etc. Stepwise multiple regression analysis was used to determine the relationship between the significant variables and the change in functional exercise capacity using the rollator.

Statistical analysis and graphing were undertaken using two statistical software packages (SigmaStat, version 2.03, and SigmaPlot, version 5.0; SPSS Inc; Chicago, IL). For all statistical analyses, p values of 0.05 were considered to be significant.

	Results

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

 
Results are expressed as the mean of measurements taken on the two study days. No significant difference for study day was observed for any of the outcomes of interest.

Sample Characteristics
Twenty-one male subjects and 19 female subjects with severe COPD (mean [± SE] FEV₁, 36.1 ± 2.0% predicted; FEV₁/FVC ratio, 38.5 ± 2.0%; PaO₂, 65.2 ± 1.6 mm Hg; PaCO₂, 44.1 ± 0.9 mm Hg; oxyhemoglobin saturation, 91.9 ± 0.6%) participated in the study. Ten of the subjects used supplemental oxygen during exertion. Of the 40 subjects, 19 walked < 300 m during the unaided 6MWT. Subject characteristics are shown in Table 1 .

View larger version (15K): [in this window] [in a new window] [Download PPT slide]   Figure 2. Total distance walked unaided (NR) and WR (R) for the total sample (left, A), subjects who walked < 300 m unaided (middle, B), and subjects who walked > 300 m unaided (right, C). Open circles = individual data points; solid squares = mean ± SE.

View larger version (13K): [in this window] [in a new window] [Download PPT slide]   Figure 3. Distance walked unaided (NR) and WR (R) for each minute of the 6MWT for the total sample (left, A), subjects who walked < 300 m unaided (middle, B), and subjects who walked > 300 m unaided (right, C). Open circles = WR; solid circles = NR.

Duration of Rest:
Subjects rested for a mean (± SE) time of 11.9 ± 5.8 s with the rollator compared to 31.2 ± 8.7 s without the rollator (p = 0.001; Fig 4 ). This reduction in resting time when using the rollator was even greater when it was calculated for the group of subjects who walked < 300 m unaided (WR, 24.3 ± 11.6 m; NR, 64.7 ± 15.0 s; p < 0.001) [Fig 4 ]. Rest duration for each 6MWT was associated with a single rest for the majority of subjects.

View larger version (15K): [in this window] [in a new window] [Download PPT slide]   Figure 4. Duration of rest during the 6MWT when walking unaided (NR) and WR (R) for the total sample (top, A) and subjects who walked < 300 m unaided (bottom, B). Open circles represent individual data points. Solid squares represent mean ± SE.

View larger version (16K): [in this window] [in a new window] [Download PPT slide]   Figure 5. Comparison of the change in dyspnea ratings when walking unaided (NR) and WR (R) for the total sample (left, A), subjects who walked < 300 m unaided (middle, B), and subjects who walked > 300 m unaided (right, C). Open circles represent individual data points. Solid squares represent the mean ± SE.

View larger version (19K): [in this window] [in a new window] [Download PPT slide]   Figure 6. Oxygen saturation during the 6MWT when walking unaided (NR) and WR (R) for the total sample (top, A) and subjects who walked < 300 m unaided (bottom, B). Open circles represent individual data points. Solid squares represent mean ± SE.

Upper Extremity Weight-Bearing:
The amount of upper extremity weight applied to the rollator was 5.0 ± 0.3 kg (7.0 ± 0.4% of body weight) for the total group and 5.5 ± 0.5 kg (7.4 ± 0.6% of body weight) for those who walked < 300 m unaided. The amount of weight applied to the rollator was unrelated to changes in distance walked (r < 0.3; p > 0.1) or dyspnea ratings (r < 0.3; p > 0.3) with use of the rollator.

Subject Preference:
Fifty percent of subjects (n = 20) preferred walking with the rollator, 17.5% (n = 7) had no preference, and 32.5% (n = 13) preferred to walk unaided. Of the 19 subjects who walked < 300 m unaided, 14 (74%) preferred using the rollator, 1 had no preference, and 4 preferred to walk unaided. The number and percentage of subjects agreeing with specific statements pertaining to the use of the rollator are shown in Table 2 .

	Discussion

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

Functional capacity has been defined as the ability to undertake physically demanding activities of daily living.³³ An improvement in functional capacity can be manifested by walking further or by being less breathless for the same distance walked.³⁴ In this study, all of the subjects experienced a reduction in dyspnea with the rollator. Dyspnea is a distressing sensation that limits exercise tolerance, and, as such, some clinicians regard it as a primary outcome measure in the rehabilitation of patients with COPD.^{35 36 37} It has been suggested that a 1-unit change represents the minimum clinically important difference for dyspnea ratings using the modified Borg scale (Denis O’Donnell, MD; personal communication; April 6, 2000). The use of a rollator resulted in a 1-unit reduction in the perception of dyspnea for the total sample and a 1.4-unit reduction for those patients who were most disabled. These results are consistent with reports by Honeyman and colleagues⁴ and Dalton and colleagues,¹³ who found a reduction in dyspnea of > 1 unit with the use of a rollator.

Subjects with greater disability (ie, 6MWT distance, < 300 m) walked further WR. Although a minimal change in 6MWT distance of 54 m has been suggested as the threshold for a clinically important improvement, this value is based on a COPD population with an average 6MWT distance of 371 m.³⁰ Given that our subgroup walked 220 m during the unaided 6MWT, the smaller improvement of 22 m is likely to be meaningful, especially since it was accompanied by a reduction in dyspnea. Honeyman and colleagues⁴ and Wesmiller and Hoffman¹² have reported comparable improvements with the use of a rollator among individuals with similar levels of disability. The improvements observed among the more disabled subjects may be especially important as improvements in exercise performance and health status in patients with COPD after an exercise program may depend on the severity of their disability. Wedzicha and colleagues³⁸ noted that although patients with moderate disability (ie, Medical Research Council dyspnea grades 3 and 4) who were mobile outside of their homes showed improvements in exercise capacity following rehabilitation, those with severe disability (ie, Medical Research Council dyspnea grade 5) who were largely housebound showed no improvement in exercise performance following individualized physical training. Therefore, for patients with severe disability and poor physical fitness, the provision of a rollator might offer a useful adjunct to rehabilitation in reducing dyspnea and increasing exercise tolerance.

The outcome of rest duration has received little attention in the literature. In a review of studies that used time-based walking tests to evaluate functional exercise capacity, Menard-Rothe and colleagues³⁹ found none that reported total rest time as an outcome. We included a measure of rest duration as this information allows a clearer understanding of the walk test.³⁹ Our finding of a reduction in rest time of 19 s for the total group and 40 s for the more disabled subgroup supports the benefit of using a rollator, especially when considered in conjunction with the reduction in dyspnea and the improvement in walking distance observed among the more disabled subjects.

The use of the rollator was not associated with changes in ventilation or breathing pattern, an observation that is in agreement with that of Grant and Capel,¹¹ who used a respirometer to measure minute ventilation in five men with COPD and noted no change when they walked with a wheeled walking aid. Improvement in ventilation using the rollator may be contingent on being able to adopt the "forward-lean" position frequently seen among patients with COPD.⁴⁰ This position is thought to improve the effectiveness of the diaphragm, thereby reducing work of breathing.^{40 41} Whereas other studies on wheeled walking aids have used high-wheeled walkers^{10 11 14} or have adjusted the height of the aid for comfort,¹² we standardized the height of the rollator, using the approach that most clinicians adopt when prescribing walking frames.^{16 42} It is possible that the height of the rollator may have been too low to facilitate this forward-lean position.

Improvement with the rollator was not dependent on the actual amount of weight applied to the rollator, which was only 7% of the subject’s body weight. However, the provision of arm support likely did contribute to the improvement. Individuals with COPD often breathe with their accessory respiratory muscles including those of the upper arm and shoulder girdle, which have roles both in the maintenance of ventilation and in postural stabilization.^{43 44} When the arms are unsupported, such as in arm swing during ambulation, the accessory muscles increase their participation in the postural support of the chest wall. To reduce dyspnea, individuals often stabilize their arms.⁴⁵ This stabilization enables the arm and shoulder girdle muscles to act more effectively as accessory muscles of respiration.⁴⁶ Therefore, the rollator may have facilitated a reduction in dyspnea by enabling the users to stabilize their upper limbs during walking, thereby improving the effectiveness of their accessory muscles.^{43 44} In this study, we did not evaluate the electromyographic activity of accessory muscles.

Dyspnea is also influenced by emotion.⁴⁷ During exercise, an individual may breathe hard and not experience the sensation of dyspnea because such exertion is not accompanied by a sense of anxiety over the adequacy of ventilation.⁴⁸ Additionally, the sensation of dyspnea may occur without a corresponding change in ventilation or gas exchange.⁴⁸ Therefore, patients with COPD who are anxious may experience more dyspnea for a given amount of work than those who are not. Use of the rollator may have provided sufficient reassurance to reduce anxiety during walking to result in a reduction in their perception of dyspnea without a corresponding change in ventilation. We may in fact have underestimated the benefit of a rollator among individuals with severe COPD as, in the course of modifying the rollator to incorporate the measurement of upper extremity weight-bearing, we removed the seat. The seat provides the user with the security of knowing that he/she can rest at anytime and may, therefore, serve to further reduce the anxiety and fear many individuals with COPD have when embarking on community ambulation.

Stride length and walking speed have been shown to be altered when using various types of wheeled walking aids, especially among older subjects with no underlying lung disease.^{6 49 50 51} Although neither changed in the current study, we did observe changes in minute-to-minute variability of distance walked, reflecting improved pacing, especially among subjects with greater disability (Fig 3) .

Finally, we noted that the majority of subjects, especially individuals with greater disability, preferred using the rollator to walking unaided. Those who did not reported concerns of the perceived stigma associated with using a mobility aid and its cost (the Opal Legacy rollator retails for approximately $495 [in Canadian dollars]). Therefore, it is important to address the patient’s preferences prior to a making a clinical recommendation.^{52 53}

	Conclusion

TOP Abstract Introduction Materials and Methods Results Discussion Conclusion References

 
The use of a rollator reduced dyspnea and rest duration in stable patients with severe COPD. Those who walked < 300 m unaided or required a rest during the 6MWT benefited the most from use of the rollator, as in this group walking distance also increased. The improvement was not associated with alterations in cardiorespiratory function or gait. The effect of rollator height and its influence on respiratory muscle function, as well as the long-term effects of rollator use on functional exercise capacity and health-related quality of life will further advance our understanding of the indications for recommending the use of a rollator to patients with COPD.

	Acknowledgements

 
The authors thank Drs. Cheryl Cott and Scott Thomas for their constructive comments in the planning and execution of the study, David I. Wang for his assistance with data analysis, Donna Clow for her help with subject recruitment, Therapists Choice Medical Supplies for provision of the rollator, and the individuals who participated in the study, for their time, kindness, and genuine desire to help others.

	Footnotes

 
Abbreviations: NR = no rollator; SGRDQ = St. George’s Respiratory Disease Questionnaire; 6MWT = 6-min walk test; WR = with rollator

Support was received from Glaxo Wellcome (unrestricted educational grant), the Clinical Evaluation and Research Unit of the West Park Healthcare Centre, and the West Park Foundation. Sherra Solway was supported by the Ontario Respiratory Care Society and the Canadian Physiotherapy Cardiorespiratory Society through fellowship awards.

Received for publication September 7, 2001. Accepted for publication December 24, 2001.

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