Abstract:

Context

:

Excess prevalence of balance deficit in COPD has been reported, suggesting a link between these two conditions

Aims

:

Balance being affected in Chronic Obstructive Pulmonary Disease (COPD) is generally accepted. However, determining the cause of impaired balance in COPD has not been directly investigated. Thus, this study aimed at find out the underlying cause of balance deficits in COPD.

Settings and design

: Case control Study

Methods and material

A total of 48 patients aged 40-65 years, with COPD, diagnosed clinically and by Spirometry were compared with 39 healthy non-COPD controls matched for age, BMI and nationality. The functional balance (Brief-Balance Evaluation Systems Test and Berg Balance Scale), respiratory muscle strength (maximal Inspiratory pressure and maximal expiratory pressure), lower limb muscle strength (repeated chair stand test), functional capacity (6-minute walk test) and BODE index were assessed in COPD cases and control group.

Statistical analysis used

:

Independent t-test was used to determine between group differences for continuous variable. Correlation were assessed to determine the relationship between variables in moderate and severe COPD groups

Results

: Significant difference was observed in all the components between COPD and healthy controls. A strong association was found between Brief-BES test and posterior sway with eyes open (p=0.006)

Conclusions

: The findings indicate that balance is impaired in COPD which may increase the chances of falls. There is a need of future research to evaluate the role of COPD specific balance training as a comprehensive management of patients with COPD.

Key-words

: COPD, Balance, Peripheral muscle strength, respiratory muscle strength, functional capacity, BODE index.

Introduction

Chronic obstructive pulmonary disease (COPD) is primarily a pulmonary disease and a leading cause of morbidity and mortality worldwide. It has an economic and social burden that is both substantial and increasing.The increasing burden of the disease will be projected as fourth leading cause of death by the year 2030.

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In a previous study the overall prevalence of COPD in India is to be 4.36% where the prevalence among males and females were 5.32% and 3.41% respectively.

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Recently in past 10 years its extra-pulmonary manifestations are increasing and are recognised as contributing to the severity of the disease. Some of the extra-pulmonary manifestations are loss of weight, muscle dysfunction (respiratory and peripheral muscles) osteoporosis, cardiovascular diseases, anaemia, depression and anxiety.

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Numerous factors have been identified to contribute to peripheral muscle changes including airflow obstruction, disuse, oxidative stress, hypoxia, malnutrition, systemic inflammation and medication.

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To maintain postural control both in static and dynamic posture sensory, musculoskeletal and neural components should work in synchrony. Previous studies showed deficits in balance or postural control both in static and dynamic postures in COPD.

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These studies proposed a number of mechanisms for reduced level of postural control and increased fall risk in COPD. These are decreased level of physical activity

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peripheral muscle weakness

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and altered trunk muscle mechanics

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and Somatosensory deficits.

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Many studies had reported impairment in functional balance, mobility, postural sway

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, functional capacity

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, upper and lower limb muscle strength

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and static postural control

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in moderate to severe COPD.

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These studies suggested that balance is impaired in COPD and the factors which affect the balance should be identified so that a COPD specific   balance rehabilitation protocol would be designed. Therefore, this paper aimed to identify the relationship between balance and respiratory muscle strength, functional capacity, BODE Index, postural control and lower limb muscular strength in COPD patients as compared with age and BMI matched healthy subjects.

Methodology

The study is Case control Study in nature. The permission to conduct the study was taken from ethical committee of Indian spinal institute centre, Institute of rehabilitation sciences and National institute of tuberculosis and respiratory disease, New Delhi.

A total of 48 COPD patients aged between 45-65, and BMI matched healthy controls were randomly assigned after meeting the inclusion  criteria of diagnosed stable, moderate and severe COPD as per GOLD guidelines updated in 2016

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, and those who maintained saturation at room air above 90% were included in both groups. Eligible patients were informed and provided with patient information sheet. Before baseline evaluation, a written consent was taken from the participants. If the participant presented with diagnosed pulmonary condition other than COPD or any other disease were excluded. Other exclusion criteria included were; Patient using invasive & non-invasive mechanical ventilation.

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Any diagnosed visual or vestibular deficits that could affect postural control.

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Any participant with dyspnoea at rest.

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Cognitive impairment. Evaluation of functional balance, postural sway, respiratory muscle strength (PImax & PEmax), and lower limb muscle strength, functional activity, Pulmonary functions and BODE index was done.

Pulmonary function results were obtained through Spirometry followed by evaluation of respiratory muscle strength using pressure manometer in both COPD and controls. All subjects underwent a clinical balance performance test and test for lower limb muscle strength. Postural sway and functional capacity were measured by sway meter and six minute walk test respectively.

Clinical balance measures

Clinical balance tests included the Brief- Balance Evaluation Systems Test (Brief-BESTest) and Berg Balance Scale (BBS). The Brief-BESTest was created from 6 items of the BESTest, 1 from each section, with 2 items (single-leg stance and functional forward reach) being scored bilaterally, resulting in an 8-item test. Brief- BESTest is defined by Timed “Up & Go test, push & release laterally, closed eye standing on foam, strength of hip abductor, functional reach and one leg stance. Items are scored from 0 to 3, and the scores are summed to obtain a total score out of a possible maximum score of 24 points. Higher scores indicate better balance performance. Brief-BESTest demonstrated reliability comparable to that of the Mini-BESTest and potentially superior sensitivity while requiring half the items of the Mini-BESTest and representing all theoretically based sections of the original BESTest.12 Berg balance scale (BBS) was developed to measure balance among older people with impairment in balance function by assessing the performance of functional task. It is a valid instrument used for evaluation of the effectiveness of intervention and for quantitative descriptions of function in clinical practice and research. The BBS consisted of 14 items that are scored on an ordinal scale of 0 to 4. A score of 0 is given if the participants are unable to do the task, and a score of 4 is given if the participants are able to complete the task. The maximum total score on the test is 56. The items vary from simple mobility task to complex ones. Time taken to complete the test is 15- 20 minutes. Individuals who score 41 -56 have low fall risk; 21-40 have medium fall risk and 0 -20 have high fall risk.

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Lower limb muscle strength

The repeated chair stand test (number of sit-to-stands the subject can complete in 30 s) was used as a measure of lower body strength.

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Postural sway

Sway meter was constructed with a 40 centimetre rod attached to a belt. One end is attached to anterior superior iliac spine and other to the pen which rests on a horizontal place at the level of anterior superior iliac spine. The sway meter was placed posterior to the subject so that the vision could be excluded. Subjects were asked to stand on the paper sheet with foot prints. The distance between two feet would be around three inches. The graph sheet was placed behind the subject. The graph was levelled in such a way; the rod was maintained in horizontal position. The individuals were standing straight with their hands by their sides. Duration of each trial was 30 seconds. A starting point was marked on the graph sheet. The subjects were allowed to take rest of 5-10 second, after each trial. A total of six trials were done. The first three trials were done with eyes open and then three trials with eyes closed. Maximum duration of all trials was 6-7 minutes. Maximum deviation out of the trials was taken for analysis.

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Respiratory muscle strength testing

Maximal  inspiratory pressure ( PImax )  and  the  maximal  expiratory  pressure  ( PEmax) measures the respiratory muscle strength. The   PImax reflects the strength of the diaphragm and other inspiratory muscles, while the PEmax reflects the strength of the abdominal muscles & other expiratory muscles.

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Pulmonary functional test (PFT)

Spirometry was done to evaluate pulmonary function testing. In order to determine whether the patient has lung problem or not, PFT is performed which measures lung capacities. For spirometry, forced vital capacity (FVC) was measured by having the patient, after inspiring maximally, expire as forcefully and rapidly as possible into a Spirometer for a minimum of 6 seconds. After 3 acceptable FVC manoeuvres have been obtained, the manoeuvre with largest sum of FVC and forced expiratory volume at 1 s (FEV1) was selected for interpretation.

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Functional capacity

The six minute walk test is being simple, valid, self-paced test to assess the sub maximal level of functional capacity and is better tolerated & more representative of activity  of daily living. It require 30 meter corridor for its implementation. Patients are instructed to rest 10 minutes before the test. Variables such as age, height, weight blood pressure, heart rate, respiratory rate, Sp02, dyspnea and fatigue are measured before the test start, immediately after the test and after 5 minutes.

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BODE Index

BODE Index consists of four components that includes body mass index (BMI), degree of air flow obstruction as measured by FEV1(O),  dyspnea measured by MRC dyspnea scale (D) and exercise capacity measured by six minute walk distance (E). These variables are incorporated into a multidimensional scale ranged from 0 (least risk) to 10 (Highest risk).

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Statistical analysis

Statistical package SPSS version 20, Microsoft Excel 2007 was used to analyze the data where mean and standard deviation was derived. Independent sample t-tests were used to determine between group differences for continuous variables. Pearson’s coefficient of correlation was used to determine the relationship between variables in COPD, moderate and severe group. A probability level, P < 0.05 was used as the criterion for statistical significance.

Results

Baseline characteristics of the both group are provided in Table 5.1. Results from the clinical balance tests, functional capacity, respiratory muscle strength, postural sway, lower limb muscle strength and BODE index in COPD and controls are shown in Table 5.2. Lower Brief-BESTest and BBS score, reduced six minute walk distance, respiratory muscle strength, lower limb muscle strength and BODE index were evident in COPD as compared to controls (all p= 0.01). There was no difference between groups in all components of postural sway except lateral sway with eye closed (p= 0.01). A similar significant difference was observed in Brief-BESTest and BBS scores between COPD and controls when divided on the basis of age and severity (p< 0.05).

Table 5.1:- Demographic details of COPD and Control group.

* Level of significance < 0.05

5.1:- Results from the clinical balance tests, functional capacity, respiratory muscle strength, postural sway, lower limb muscle strength and BODE index are shown in table 5.2. Among COPD, lower Brief-BESTest and BBS scores, reduced six minute walk distance, respiratory muscle strength, lower limb muscle strength and increased BODE index were significant compared to the controls (all p= 0.01). There was no difference between groups in all components of postural sway except lateral sway with eye closed (p= 0.01)

Table 5.2 Comparison between COPD and Control group regarding various parameters