The effect of walking aids on exercise capacity and oxygenation in elderly patients with chronic obstructive pulmonary disease

Age and Ageing, Nov, 1998 by Jamal Roomi, Abebaw M. Yohannes, Martin J. Connolly

Spirometry was performed using a Compact C spirometer (Vitalograph Ltd, Buckingham, UK), which was calibrated daily. Patients performed FVC tests seated and wearing a nose clip. Three reproducible readings ([ or -] 5% [FEV.sub.1]) were taken at 1 min intervals and the best result recorded. Predicted values were obtained from the equations given by Cotes [6]. Exercise capacity was assessed by a 6-min walk test [7].

Patients attended the geriatric day hospital on four separate days. Spirometry and reversibility was measured on the first visit. Each subject performed one 6-min walk test at each visit, either unaided or with a Zimmer frame, rollator (wheeled frame) or gutter (high, wheeled) frame in random order. All walk tests were performed at the same time of day, under identical conditions, 30min after the inhalation of nebulized salbutamol (5 mg) and ipratropium (0.5 mg), and at least 2 h after the last meal. Repeat walk tests were monitored by different blinded investigators. Investigators acted as time-keepers, following (not leading) the patient and carrying the pulse oximeter (see below). Each walk test was begun at a different point along the course to minimize the ability of the patient to compare his or her performance with that in previous tests. Patients were allowed to rest during the 6 min, but advised that the aim was to walk as far as possible in the allotted time and that timing would continue when they were resting.

Exercise-related arterial oxygen desaturation was assessed during the walk test by a portable pulse oximeter (Pulsox-7, Minolta, DeVilbiss, Heston, UK) using a finger probe. Baseline oxygen saturation immediately before the start of the walk test and the minimum saturation during the test were noted. Exercise-related desaturation (%) was defined as baseline saturation minus minimum saturation.

Statistical analysis

Paired t-tests were used to compare differences in 6-min walk distance and oxygen saturation. Significance was defined at the 5% level.

Results

All data are presented as mean values (standard error).

Twenty-seven patients (15 men) with a mean age of 75.1 (range 70-82) years were recruited. Mean pack-years smoked (1 pack-year = 20 cigarettes per day for 1 year) was 28.8 (5.6) and mean [FEV.sub.1] was 1.01 (0.07) 1, representing 49.5 (4.2)% of the predicted value. Mean [FEV.sub.1]/FVC ratio was 44.2 (2.0)%.

Table 1 presents the walk distance and fall in oxygen saturation for each walk test. Subjects using a rollator frame showed a walk distance and oxygen desaturation very similar to that seen when walking unaided. When a Zimmer frame was used, walk distance was shorter but there was no significant change in oxygen desaturation. In contrast, using a gutter frame resulted in greater walk distance and significantly less oxygen desaturation.

Table 1. Six-minute walk distances and oxygen saturation
measurements

                      Mean value (SEM)

                                         Oxygen saturation (%)

                   Walk distance (m)      At rest    Fall during
                                                       exercise

Unaided               210 (16)           93.0 (0.7)   6.0 (1.1)
With Zimmer frame     165 (13)(a)        93.0 (0.8)   6.0 (0.7)
With rollator frame   212 (17)           92.3 (17)    5.4 (0..9)
With gutter frame     234 (15)(b)        93.0 (0.5)   3.7 (0.8)(c)