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新型下肢驅動輪椅之設計、開發與評估
The Development and Evaluation of New Lower Limbs Propelling Wheelchair
計畫類別：■ 個別型計畫 □ 整合型計畫 計畫編號：NSC93－2614－B－006－001－
執行期間： 93 年 8 月 1 日至 95 年 10 月 31 日
計畫主持人：張冠諒
共同主持人：陳家進、官大紳、葉純妤、蔡昆宏
計畫參與人員：張冠諒、陳家進、官大紳、葉純妤、蔡昆宏及多位研究 生
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本成果報告包括以下應繳交之附件：
□赴國外出差或研習心得報告一份
□赴大陸地區出差或研習心得報告一份
■出席國際學術會議心得報告及發表之論文各一份
□國際合作研究計畫國外研究報告書一份
處理方式：除產學合作研究計畫、提升產業技術及人才培育研究計畫、
列管計畫及下列情形者外，得立即公開查詢
■涉及專利或其他智慧財產權，□一年■二年後可公開查詢
執行單位：國立成功大學醫學工程研究所
中 華 民 國 九十六 年 一 月 三十 日
Table of Contents
中文摘要………...………... I Abstract……….……….III
1. Introduction………..………..…1
2. Equipment 2.1 Wheelchair base………..………..3
2.2 FES controller……….………..4
2.3 System integration………..………...……..4
3. Clinical evaluations 3.1 Participants………...……..6
3.2 Test equipments……….…..6
3.3 Protocols………...…………7
3.4 Statistical analysis………..………...…….14
4. RESULTS 4.1 Results of Field Test………..….16
4.2 Results of Laboratory Test………..………..17
5. Discussion……….…………..………...….20
6. Future works………..……….22
References……….……..………..….….23
中 文 摘 要 中 文 摘 要 中 文 摘 要 中 文 摘 要
約有三分之二的中風患者具有神經生理方面的損傷，此會導致相當多的不方 便，最常見的便是單側肢體癱瘓，而其對日常生活所造成的影響也最大。輪椅提 供了最佳的移動性及穩定性，因此成為中風病患最主要的移行輔具。然而對於單 側肢體健全的中風偏癱患者而言，操作雙手驅動之傳統輪椅，不但會因為不對稱 的施力方式造成輪椅偏向，也容易在斜坡上發生危險。
針對中風偏癱患者之使用需求，開發一款新型下肢驅動輪椅，並加入功能性 電刺激的功能以協助患者患側腳的施力以驅動輪椅。並為了瞭解新型輪椅之操控 性及心肺反應，篩選八位中風偏癱患者參與臨床評估。評估方法則運用實地測試 及實驗室測試，來檢測新型輪椅之操控性與患者在使用此型輪椅之運動心肺功能 及使用後患側下肢肌肉張力變化情形，與現有傳統輪椅進行比較。
臨床評估的結果顯示，在實地測試方面：相較於傳統手動輪椅，新型下肢驅 動輪椅耗費較少的完成時間與偏移百分比，生理耗能指數與受試者的自覺用力係 數方面也顯示新型輪椅在操作上較為輕鬆，患側腳之肌肉張力也有明顯的下降，
由此可知此型輪椅確實具有較佳的操控性。在實驗室測試方面：新型輪椅在相同 驅動距離下，平均速度、最大攝氧量與生理耗能指數等都比傳統手動輪椅者小，
受試者自覺用力係數也較低，顯示驅動新型輪椅較輕鬆；此外，在完成運動測試 後，使用新型輪椅的患者患側腳肌肉張力明顯的下降。整體評估結果顯示，新型 下肢驅動輪椅不論是否有功能性電刺激的輔助，在相同條件控制下所需要的能量 消耗較低，且驅動效率較高，是一款較為符合中風偏癱瘓者使用之輪椅。
本研究整合中風偏癱患者功能性電刺激輔助下肢驅動輪椅之開發與臨床評 估，兼顧使用者之臨床需求與輪椅實用性，為患者找到一種有效率且簡易的移行 方式。
關鍵詞：偏癱患者、功能性電刺激、下肢驅動輪椅、實地測試、運動心肺功能測 試、肌張力
Abstract
In general, there are about two-thirds of stroke survivors suffered from residual neurologic deficits that will lead to awkwardly, such as hemiplegia and hypertonia.
These existent motor function impairments will not only reduce exercise ability, consume much more energy, but also constipate the independent of daily life. In order to recover mobility and avoid accident in daily life, a variety of mobility devices were adopted for hemiplegic patients, such as canes, walkers and wheelchairs. Due to well stability, wheelchair is an important mobility aid of daily life. However, manual wheelchair was designed for patients suffered from parapligia. The asymmetrical propel manner will be strait and dangerous for hemiplegic patients who only have unilateral unaffected side.
In the present study, functional electrical stimulation (FES) assisted leg- propelled wheelchair, (FA/ LW), was developed for hemiplegic patients. In addition, clinical evaluation was conducted to realize the controllability of FA/ LW and cardiopulmonary response as patients operating FA/ LW. Eight hemiplegic patients were recruited to participate in clinical evaluation including Field Test and Laboratory Test.
The results of Field Test revealed that FA/ LW were significant lower than manual wheelchair(MW) on finish time and deviation percentage. Moreover, physiological cost index（PCI）and rating of perceived exertion (RPE) of FA/ LW were also about lower than MW; These meant that FA/ LW had higher propelling efficiency than that of MW. The muscle tone of affected leg significantly decreased after propelling FA/
LW. The results of Laboratory Test revealed that average velocities, maximum oxygen consumption (
.
V O2max), PCI and RPE were lower in FA/ LW than in MW after completing the same distance. The muscle tone of affected leg significantly decreased after propelling FA/ LW.
Regard with the results of clinical evaluation, FA/ LW were better in controllability and cardiopulmonary response than MW. Therefore, new developed leg-propelled wheelchair with the assistance of FES was an efficient and easy operated mobility device for hemiplegic patients.
Keywords: hemiplegic patient, functional electrical stimulation, leg-propelled wheelchair, field test, cardiopulmonary exercise test, muscle tone
1. Introduction
In general, there are about two-thirds of stroke survivors suffered from residual neurologic deficits that will lead to awkwardly, such as hemiplegia and hypertonia [1].
Stroke patients with hemiplegia often have reduced mobility due to asymmetrical movement and reduction in exercise capacity. The exercise capacity of hemiplegic patients has been found to be approximately 40% below that of age- and gender- adjusted norms for sedentary individuals [2] [3]. And these existent motor function impairments would not only reduce exercise ability, consume much more energy, but also constipate the independent of daily life [4]. To improve difficult locomotion and reach the purpose of independent living, one of the rehabilitation goals for stroke patients was to regain ability of ambulation for independent living. Not all of the patients after stroke could get into ambulation training immediately. Some researchers reported that about 85% of hemiplegic patients were still impaired on gait speed at three months after stroke. Moreover, aggravated patients would lead to atrophy or contracture, even couldn’t walk due to lake of adequate exercise in legs [5] [6].
Most stroke patients used manual wheelchair to assist their locomotion, even though the manual wheelchair was not designed for the unilateral operated patients [7].
There was much deficiency for hemiplegic patients using manual wheelchair. It reported that when propelling up an incline, hemiplegic patients using the unilateral propulsion pattern deviated more toward the hemiparetic side, used more propulsive frequencies and slower than the subjects with both arm propulsion [8]. Moreover, it is difficult and uncomfortable for hemiplegic patients to propel the manual wheelchair over a long distance or changing direction. When hemiplegic patients made an effort to propel the manual wheelchair by swinging their trunk as compensation, their posture became unbalance [9]. Accordingly, how to achieve the locomotion purpose effectively and maintain muscle strength in leg are quite important for the design of mobility device.
In general, legs were used daily for locomotion and weight-bearing, some researches indicated that the workload for leg exercise was greater than that for arm exercise and cardiopulmonary responses due to arm exercise were higher than those of leg exercise at the same workload [10] [11]. No matter using reciprocate or circulate propulsion pattern, various devices that allowed propulsion with leg have been investigated and patented [12] [13]. In the reciprocated pattern, linear [12] and oscillating pivoting [14] motion were reported. However, reciprocated pattern causes energy to loss when legs keep accelerating/ decelerating constantly because of non-continuity of movement [15]. In the contrary, circulate pattern such as cycling motion for force input source was more effectively [14]. These greatly researches were
contributed to the mobility with assistance of leg propulsion, no matter collocate reciprocated or circulated exercise. However, those devices were designed for patients with paraplegia, not for stroke patients. For this reason, the characteristic of unilateral limbs weakness should be considered in depth.
In the recent years, some researchers considered the physiological characteristics of stroke patients and specialized wheelchair for hemiplegic patients were developed.
Tsai et al developed a reciprocal propelling wheelchair by using ankle dorsiflexion/
plantar flexion and arm of unaffected side [16]. When ankle of unaffected leg moving repeatedly, force could be transmitted to rear wheel of affected side. However, this type of wheelchair only used the limbs of unaffected side, but with no rehabilitation effects for affected limbs. Makino et al reported a both leg-pedaling wheelchair with the cycling mechanism mounted on the front of it [9]. Although this wheelchair could allow affected leg driven passively, but the asymmetrical propel manner would increase the work load of unaffected leg and decrease the propel efficiency. Because of that, the mobility device designed for stroke patients can propel effectively, achieve the purpose of locomotion and provide adequate active exercise to avoid atrophy of lower extremities and reduce cardiopulmonary function is necessary.
Functional electrical stimulation (FES) has already been widely acknowledged in rehabilitation medicine, it had generally been used in clinical practice to retrain muscle strength, correct drop-foot, and improvement of cardiopulmonary function for stroke patients [17]. However, the leg-propelled wheelchair with the assistance of FES using by hemiplegic patients has not been investigated. In order to increase muscle force shrinkage, promoting muscle activation and the reestablishment of motor function; the effect of electrical stimulation to affected leg was concerned in the present study.
The purposes of the present study were to (1) develop a novel wheelchair, which allowed hemiplegic patients to propel the wheelchair by their legs with the assistance of FES. (2) In order to realize the controllability and physical efficiency, the preliminary evaluation was conducted to qualify the performance of the novel wheelchair comparing to a commercial manual wheelchair.
2. Equipment
The new FES assisted leg-propelled wheelchair (FAW) consisted two major parts:
one is wheelchair base, the other is FES controller.
2.1 Wheelchair base
The wheelchair base was modified by commercial manual wheelchair (KM-8520, KARMA, TAIWAN). With regard to higher propelling efficiency, the circulate motion with cycling mechanism was mounted in the front of wheelchair base as force input interface. Through high efficiency shaft drive transmission system (SDTS, SUSSEX, TWIWAN), a non-chain drive shaft; the leg generated force could be transmitted to gear set mounted in the rear of wheelchair base (Figure2.1).
Figure 2.1 Mechanical design of wheelchair base. (a) rotatory AFO, (b) SDTS, (c) angular encoder, (d) steer lever, (e) driving wheel (f) gear set.
There are three positions of gear set including forward, neutral and backward. As clutch was changing to different positions and meshing to different gears, the driving direction will be changed. As clutch was changing to neutral position, even users propelling the cycling mechanism wheelchair base could not move anywhere.
The steer lever was mounted on the wheelchair base which was attached on the caster on the unaffected side for the direction turning. In addition, a switch was mounted on the grip. By operating switch, patient could mesh different gears and decide the
(a)
(c)
(b) (d)
(e) (f)
direction of wheelchair base. The steer lever also equipped with brake lever to reduce speed by users during movement and ensure the user’s safety. Besides, two clipper brakes, connected to brake lever, were mounted on each rear wheels.
The ankle foot orthoses (AFO) were mounted on the end of cranks to replace pedals. It could prevent the hip joint of affected leg from abduction. The rotatory joint of AFO allow ankle be driven passively during the cycling motion.
2.2 FES controller
The high performance two-channel FES controller consists of a 89C51 microprocessor, an angular encoder (MES-30-360P, MTL, JAPAN), a 8-bit digital to analog converter (DAC) and a simulator.
The microprocessor control the timing of the stimulation pulse, the pulse rate and width were set at 20 Hz and 300 µs, respectively. The constant current output can reach up to a maximum of 100mA with independent output for each channel using a 12V battery. The electronic circuits of FES controller, including operation Liquid Crystal Display (LCD) panel, interfacing to the stimulator and encoder, are integrated on a single printed-circuited-board (PCB) with consuming power less than 2 watt of power. Two sets of 1.8”x 3.8”surface electrodes were selected to deliver transcutaneous current to the hamstrings and quadriceps of affected leg.
2.3 System integration
Functionally, the stimulator is triggered by the position of pedal to stimulate the quadriceps for knee extension and hamstrings for knee flexion. The configuration of FES-assisted propelling wheelchair (FAW) was showed as (Figure 2.2). An encoder mounted on the shaft of crank the signal could be transmitted to the FES controller.
The controller could realize the current position of each pedal and stimulates the subject’s affected leg to generate propelling force and reach circular motion.
In order to determining the ranges of electrical stimulation for the affected leg, the EMG signal of the quadriceps and hamstrings were collected simultaneously during cycling motion by normal subjects [18]. The muscle contraction sequence of lower extremities was analyzed and then the stimulation patterns were extracted from normal subject was applied to this study.
The proximal horizontal point of circulate motion was defined as 0°. The stimulation current will be onset as pedal of affected leg pass through 60°~180° for the quadriceps and 200°~290° for hamstrings. The stimulation current was set up by the therapist. The intensity of ES current was increasing reach to elicit muscle contraction of thigh but not feel pain by the patients. Therefore, patient could operate this
wheelchair by unaffected leg with voluntary movement and affected leg with assistance of FES.
Figure 2.2 Configuration of the FES-assisted propelling wheelchair.
Ch1 to quadriceps
ES of quadriceps
ES of hamstring 0°
90
180°
270°
Hip
Stimulator
Microprocess
A/D converter
EPROM Ch2 to hamstring
Affected FES
Controller
Angular encoder
3. Clinical evaluation
3.1 Participants
There are 6 male and 2 female suffering from stroke were recruited from Subsidiary Rehabilitation Hospital of Medical University in this study. All subjects signed an informed consent approved by the Medical Ethical Committee of the Medical University. Among 8 subjects, four subjects with right side hemiplegia and four with left side hemiplegia. Inclusion criteria included (1) sufficient consciousness and communication ability to understand how to operate each type of wheelchair and the potential risks of this study, (2) residual neurological deficits due to stroke, (3) preserved neurological function on unilateral lower extremity, (4) unable to move independently, (5) affected leg could finish cycling motion passively. (6) the affected leg ability of all subjects in this study ranged from Brunnstrom’s Motor Recovery Stage II ~IV, and (6) with evident ankle spasticity graded 1~3 on the modified Ashworth scale (MAS). Table 3.1 listed the basic data of all the participants.
Table 3.1 Characteristics of eight participants
No Sex Age Onset
time
Affected side
Pathology Brun. St. MAS
01 M 58 4 L H III 2
02 F 44 5 L H III 3
03 M 65 2 L I IV 1
04 F 46 2 R I IV 1
05 M 38 2 L H II 3
06 M 50 4 R I III 1
07 M 38 2 R H III 3
08 M 64 2 R I IV 1+
Brun. St.: Brunnstrom’s Motor Recovery Stage.
H: hemorrhage/ I: ischemia
3.2 Test equipments
Three types of wheelchair were used in this study and introduced as follows: (1) FES assisted leg-propelled wheelchair (FAW), (2) leg-propelled wheelchair (LW), and (3) manual wheelchair (MW). The wheel tires of both wheelchairs were all changed as 24”3/8 pneumatic tire before test. All subjects were asked to practice each type of these three wheelchairs for at least 15-min a day, 3 times in one week, to get used to the ways of operation.
3.3 Protocols
3.3.1 Field Test Protocol
Patients propel each wheelchairs follow the red oval-shaped trail with 200m, and kept the wheelchair in the boundary as possible (Figure 3.2). They operate wheelchair following the path clockwise and anti-clockwise three times respectively. For maneuverability evaluation, video record was made when patients were executing the tasks. Then the physical therapists reviewed the video carefully to record the finish time, deviation frequencies overstepping the boundary, and deviation period (the duration out of boundary) of time in the straight and curve regions for the three kinds of wheelchairs, respectively. The deviation percentage was defined by dividing the deviation period of time by finish time (Figure 3.3).
(A)
Figure 3.2 (A) The oval-shape trail of Field Test.
Figure 3.3 Flowchart of Field Test
Measuring pre-MAS of affected leg
Measuring resting blood pressure Recording resting HR in 2 minutes
Starting the Test
LW
Follow oval-shaped trail
Anti-clockwise 100m
FAW LW
Clockwise 100m
Ending the Test
Measuring post- blood pressure Recording post-HR in 5 minutes
Measuring post-MAS of affected leg
Monitoring HR change and recording for finish time, deviation frequency and deviation time
Measuring RPE
For propelling efficiency measurements, a heart rate monitor (PE 4000 SPORT TESTER, POLAR, FINLAND) was worn by each subject, and heart rate (HR, beats/min) was recorded every minute. Before test, the resting heart rate was measured for 2 minutes. In the end of propelling test, HR collected again as post HR.
The energy consumption could not be determined only by oxygen consumption (
.
V O2). Generally, the workload of submaximum exercise test was increased by a certain increment each time. For workload limited exercise protocol, subject should provide enough output to counter the workload. In such protocol, HR changed and
.
V O2 could be estimated directly as energy consumption index. Considering the workload limited test was not suitable for stroke patents due to great variation of lower limb strength and muscle tone. Instead, the distance limited exercise test under comfortable condition could be a better protocol. Due to varied velocities with different wheelchairs, the HR change and
.
V O2(SS) were normalized to velocity as the index of efficiency. The physiological cost index (PCI) was announced and calculated by using MacGregor’s formula PCI=HR(P)-HR(R)/ average velocity, where HR(P) was the post-exercise heart rate, and HR(R) was the average resting heart rate. Besides, the definition of oxygen cost (OC, ml/kg/m) was the average steady-state oxygen consumption (
.
V O2(SS)) divided by average velocity (OC=
.
V O2(SS)/ average velocity ) [19] [14]. The PCI (beats/m) was obtained by subtracting the resting HR from the post HR and dividing the result by the average velocity.
In addition, the subjective rating scale, rating of perceived exertion (RPE) was also a major measurement method. It has been found to be a valuable and reliable indicator in monitoring and individual’s exercise tolerance. Borg’s RPE scale was developed to allow the exerciser to subjectively rate his/ her feelings during exercise (Borg, 1985). The RPE scale was showed in Table 1.1.
Table1.1 Scale of rating of perceived exertion (RPE)
Scale Description Scale Description
6 14
7 Very, very light 15 Hard
8 16
9 Very light 17 Very hard
10 18
11 Fairly light 19 Very, very hard
12 20
13 Somewhat hard
The Borg’s 6-20 scale, on a scale of 6 (nothing at all) to 20 (very, very hard) was used to measure subjective exertion at the end of each test and to compare the peak efforts during propulsion. The criteria to stop the test included: (1) HR increases continuously and greater than 85% of predicted maximum HR (220-age); (2) subject showed the sign of poor perfusion or volitional fatigue, (3) subject requested to stop.
Besides, in order to realize the change of muscle tone of leg.
Ashworth scale have widely used in the study of spasticity, and are the present yardstick against which newer, more exact methods must be compared. Before and after exercise test, MAS was measured by the same physical therapist and defined as change of MAS. The Ashworth scale is a 5-point rating scale for measuring muscle tone, with rating from 0 (“no increase in tone”) to 4 (“extremity rigid in flexion or extension”). In order to increase the sensitivity of the scale, they added an extra item to the lower end (grade 1+) to be the modified Ashworth Scale (MAS). The patient is examined in a comfortable position, usually supine or sitting, and muscle stretch reflexes and passive muscle tone are assessed bilaterally and separately for the upper and lower extremities. The scale of MAS was showed in Table 1.2.
Table 1.2 Scale of modified Ashworth Scale (MAS) 0 No increase in muscle tone
1 Slight increase in muscle tone. Manifested by a catch and release or by minimal resistance at the ROM
1+ Slight increase in muscle tone. Manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM 2 More marked increase in muscle tone through most of the ROM, but
affected parts easily moved
3 Considerable increase in muscle tone, passive movement difficult 4 Affected part(s) rigid in flexion or extension
The Field Test parameters include:
(1) Maneuverability: finish time (F), deviation frequencies (F) and deviation percentage (F),
(2) Propelling efficiency: HR change (F), PCI (F) and RPE (F), (3) Change of muscle tone: Change of MAS (F)
3.3.2 Laboratory Test Protocol
Three types of wheelchair including LW, FAW and MW were securely mounted on resistance-free roller. The traveling distance (m) and velocity (m/min) were measured by using a speedometer (CC-VL500, CAT EYE®, JAPAN). The exercise tests of each three wheelchairs were completed on separate days within a week.
(A) Cardiopulmonary fitness
Before exercise test, the resting heart rate (HR) and expired gas were recorded for 2 minutes, and then the test was conducted by propelling a wheelchair for 200m as fast as possible in a comfortable condition. For safety consideration, the HR and expired gas were recorded for 5 minutes until the subjects were returning to the resting condition. The flowchart of Laboratory Test was showed as Figure 3.4.
Figure 3.4 Flowchart of Laboratory Test
Monitoring HR change and expired gas (
.
V O2) Measuring resting blood pressure
Recording resting HR in 2 minutes
Starting the Test
LW
Propelling or wheeling for 200m as fast as possible in a comfortable condition
FAW LW
Ending the Test
Measuring post- blood pressure Recording post-HR in 5 minutes Measuring muscle tone of affected leg
pre- exercise H reflex
pre- exercise MAS
Measuring muscle tone of affected leg pre- exercise H reflex
pre- exercise MAS
Measuring RPE
A heart rate monitor (PE 4000 SPORT TESTER, POLAR®, FINLAND) was worn by each subject to record subject’s heart rate (HR, beats/min). The expired gas was collected and analyzed by using a breath-by-breath gas analysis system (CORTEX METAMAX® 3B, GERMANY), which was also used to record the respiratory data every 15 sec (Figure 3.5).
Figure 3.5 A 44 years female stroke patient with left side hemiplegia (No. 02) propelling LW on the resistance-free roller.
Gas analysis measurements included oxygen consumption (
.
V O2, ml/min/kg),
ventilation volume (
.
VE, l/min), respiratory exchange ratio (RER), in which average
steady-state (the last 1 minute)
.
V O2(SS),
.
VE(SS) and RER(SS) were measured in the ongoing study. The PCI (beats/m) was also obtained by subtracting the resting HR(R)
from the post HR(SS) and dividing the result by the average velocity, where HR(SS) was the average steady-state working heart rate, and HR was the average resting heart rate.
Moreover, the OC ( ml/kg/m) was obtained by subtracting average steady-state oxygen consumption (
.
V O2(SS)) divided by average velocity. The RPE was also conducted in Laboratory Test using the same scale. The criteria to stop in this test were the same with Field test.
The Cardiopulmonary Exercise Test parameters include: HR changes (L),
.
V O2(SS) (L),
.
VE(SS) (L), RER(SS) (L), average velocities (L), PCI (L), OC (L) and RPE (L).
(B) Muscle Tone
Before the cardiopulmonary exercise test, the subjects sit quietly on the wheelchair; in the meanwhile the H reflex of triceps surae (TS) was recorded. The exercise test then conducted by propelling or wheeling wheelchair for 200m. After finishing trail, the H reflex of TS was recorded again while subjects took rest.
An electrical stimulator (Model S88, Grass Instruments, USA) was used to elicit TS H reflexes during quiet sitting with the test knee straight. To elicit a TS H reflex, an adhesive anode (4 x 4cm) was placed over the patella, and a bar cathode was fixed over the posterior tibial nerve. Stimulation included single rectangular pulses of 1 ms duration with a stimulation interval of at least 10 s.
H reflexes and maximal M responses of the affected soleus were elicited during quiet sitting. A bipolar surface electrode unit (1.1 cm in diameter, Iomed, Inc., USA) was taped over the soleus to record the H reflexes and the M responses. The EMG connected to a digital oscilloscope for real-time display was amplified (gain=10).
Four to six trials trials of the reliable TS H reflexes in sitting without significant background EMG activity were recorded and then filtered with a digital butterworth bandpass filter (cut-off frequency=10-1000 Hz). The consistency of stimulus was ensured by discarding automatically the trials of M responses beyond a window of 10±3% maximum M response (Mmax). The peak-to-peak amplitudes of the H reflex divided Mmax were expressed as H/M Ratio. The standardized parameters were defined as the score of post-exercise minus pre-exercise divided by pre-exercise score.
Those standardized parameters were defined as Muscle tone test parameters including H reflex (Hs (L)), Mmax (Ms (L)) and H/M Ratio (H/Ms (L)).
3.4 Statistical analysis
The descriptive statistics were expressed as the mean ±standard deviation. All experimental parameters were compared among each type of wheelchair and described as follow:
Field Test:
finish time (F), deviation frequencies (F) and deviation percentage (F), HR change (F), PCI (F) and RPE (F) and Change of MAS (F).
Laboratory Test:
HR changes (L),
.
V O2(SS) (L),
.
VE(SS) (L), RER(SS) (L), average velocities (L),
PCI (L), OC (L), RPE (L), standardized H reflex (Hs (L)), standardized Mmax (Ms (L)) and standardized H/M Ratio (H/Ms (L)).
The Wilcoxon signed ranks test was were performed using the Scientific Package for Social Sciences (version12; SPSS, Chicago, IL). One-tailed p values < 0.05 were considered statistically significant throughout.
4. Results
4.1 Results of Field Test
All subjects completed the task independently around the 200 m oval-shaped course, none of them reported adverse after the task. The results of Field Test (Table 4.1) included three sections: maneuverability, propelling efficiency and change of muscle tone.
(A) Maneuverability
As finishing 200m course including straight region and curve region, the finish time was significantly different among each wheelchair. The MW reveal significantly more finish time (F) than LW (p=0.03) and FAW (p=0.02); The LW reveal significantly more finish time than FAW (p=0.01). For deviation frequency (F), The MW got the lowest times than FW and LW but revealed no significant difference.
Regarding to deviation percentage (F), MW revealed significantly higher than LW (p=0.03) and FAW (p=0.03) respectively.
(B) Propelling efficiency
The MW got significant higher HR change (F) between LW (p=0.04) and FAW (p=0.04). With regard to efficiency, The MW also got significant higher value than LW (p=0.01) and FAW (p=0.01) in PCI (F). The RPE (F) of the MW revealed significantly higher score () than that of LW (p=0.03) and FAW (p=0.03). As result, LW and FAW were more efficient than MW in Field Test.
Table 4.1 Results of Field Test
Items LW FAW MW
Maneuverability
Finish Time (sec) 309.9±121.7*‡ 270.6±120.9† 475.5±114.6 Deviation Frequency (beats) 6.4±7.7 4.3±4.3 3.4±4.0 Deviation Percentage % 5.7±8.0* 5.0±6.3† 10.1±10.1
Propelling efficiency
HR change (beats) 14.6±6.7* 16.2±9.7† 23.5±6.7
Physiology Cost Index (beats/m)
0.38±0.2* 0.36±0.2† 0.89±0.3
RPE 10.4±1.1* 10.6±1.1† 12.3±1.3
*: significant difference between LW and MW
†: significant difference between FAW and MW
‡: significant difference between LW and FAW
(C) Muscle tone
After the 200m test, it revealed that the change of MAS (F) of affected leg was significantly decreased in propelling LW (p=0.03) and FAW (p=0.04). However, it revealed no significant change in wheeling MW (p=0.16). Five of eight subjects showed a decrease in MAS after propelling LW and FAW. As propelling LW,
There are five subjects decreasing their leg muscle tone as propelling LW and FAW. There are three subjects in LW, two in FAW decreased from 3 to 2. There is one subject decreased from 3 to 1+ in FAW. One subject decreased from 1 to 0, and one subject decreased from 1+ to 1 in both LW and FAW. In the group of wheeling MW, even the affected side does not assist to propel the wheelchair and the MAS of six subjects maintain the same, but there are still one subject increased from 1+ to 2 and one subjects increased from 3 to 4.
4.2 Results of Laboratory Test
All subjects completed the 200 meter task independently, none of them reported adverse after the task.
(A) Cardiopulmonary fitness
The responses of the cardiopulmonary exercise test were presented in Table 4.2. There were no significant differences in HR change (L) and RER(SS) (L) among the three types of wheelchair, but it revealed significant difference (p=0.02) in
.
V E(SS) (L) between LW and MW. The
.
V O2(SS) (L) of LW (9.13 ml/kg-min) and FAW (8.94 ml/kg-min) appeared significantly higher (both p=0.03) than that of MW (7.56 ml/kg-min) during exercise. No significance was found between LW and FAW. Foe average velocities (L), both LW (31.92 m/min) and FAW (30.84 m/min) were significantly much higher (both p=0.04) than that of MW (20.58m/min), but no significant differences between LW and FAW.
With regard to efficiency, the PCI (L) of FAW (0.34 beats/m) appeared significantly lower (p=0.01) than that of MW (0.55 beats/m), and the OC (L) of LW and FAW were also lower than that of MW (0.32 ml/kg-m and 0.30 ml/kg-m versus 0.36 ml/kg-m). Both PCI (L) and OC (L) demonstrated no significant difference between LW and FAW. On the RPE (L), the LW and FAW appeared significantly lower (p=0.03 in LW and p=0.02 in FAW) than that of MW. As a result, both LW and FAW were more efficient than MW. In terms of efficiency, both PCI and OC in FAW were lower than those in LW. The RPE also revealed similar trend between LW and FAW.
The results showed that FAW was superior to LW, though statistical data made no claim to obvious difference.
Table 4.2 Results of cardiopulmonary fitness of Laboratory Test
Items LW FAW MW
HR change (L) (beats) 12.81±5.32 10.56±4.81 12.41±4.83
.
VO2(SS) (L) (ml/kg-min)
9.13±1.59* 8.94±1.49† 7.56±1.41
.
VE(SS) (L) (l/min)
23.73±3.56* 22.63±4.72 20.58±4.29
RER(SS) (L) 1.11±0.10 1.11±0.13 1.10±0.06
Average velocities (L) (m/min) 31.92±11.11* 30.84±8.59† 22.71±5.95 PCI (L) (beats/m) 0.41±0.29 0.34±0.15† 0.55±1.35
OC (L) (ml/kg-m) 0.32±0.13 0.30±0.08 0.36±0.12
RPE (L) 11.00±1.85* 10.75±1.90† 13.12±2.30
*: significant difference between LW and MW
†: significant difference between FAW and MW
(B)Muscle tone
The diagram of H reflex (L), M response (L) and H/M Ratio (L) were showed in Figure 4.2. The results of Hs (L), Ms (L) and H/Ms (L) were showed in Table 4.3. The Hs (L) was significant decreased in LW (p=0.01) and FAW (p=0.02) compared to MW.
The H/Ms (L) also revealed significant decreased in LW (p=0.01) and FW (p=0.02) compared to MW. But the results revealed no significantly difference in Hs and H/Ms between LW versus FAW. The difference on H/M Ratio values was explained by changes in the H reflex. There was a significant and substantially reductions in the amplitude of the H reflex after cycling exercise.
(A) (B)
(C)
Figure 4.2 Diagram of H reflex (A), M response (B) and H/M Ratio (C). LW: leg propelling wheelchair and MW: manual wheelchair.
Table 4.3 Results of standardized parameters of muscle tone of Laboratory Test.
LW FAW MW
Hs 0.203±0.38* 0.138±0.08† -0.16±0.22
Ms 0.100±0.25 0.0438±0.0632 0.0175±0.11
H/Ms 0.07±0.22* 0.1675±0.079† -0.19±0.27
*: significant difference between LW and MW
†: significant difference between FAW and MW
0 5 10 15 20
LW FAW MW
M response (mV)
pre-exercise post-exercise
0.0 0.2 0.4 0.6 0.8 1.0
LW FAW MW
H/M ratio
pre-exercise post-exercise 0
5 10 15
LW FAW MW
H reflex (mV)
pre-exercise post-exercise
□ pre-exercise
■ post exercise
5. Discussion
Hemiplegic patients wheeled the manual wheelchair (MW) with the unaffected arm and leg, the unaffected arm needs more energy to wheel rear wheel. The unaffected leg contacts with the ground repeatedly, and attrite with floor to direction control. In the meanwhile, the affected leg wheeling MW without any exercise may leads to muscle atrophy easily over a long period of time. The FES assisted leg-propelled wheelchair (FAW) for stroke patients has developed successfully; this FAW can be driven by both legs and steering wheelchair by unaffected arm. It provided alternative means to achieve mobility for hemiplegic patients who can not ambulate independently.
With regard to the speed of FA/ LW is significant higher compare to the MW, the brake is necessary [9]. However, patients can not reduce the speed of FA/ LW by attrition rear wheels by both arms like manual wheelchair. Therefore FA/ LW equipped a brake lever on the steer lever and two set of clipper brakes on each rear wheels. This safety design allows the patients to reduce speed of wheelchair and to prevent wheelchair from deviation.
In order to reduce turning radius of FA/ LW, allowing wheelchair to be propelled by patient in reverse is necessary. Reverse function was not provided in most leg propelled wheelchair, it made certain maneuvers difficult or impossible for leg-propelled wheelchairs such as three-point turn maneuver [19]. The FA/ LW equipped with a switch mounted on the grip of steer lever. As patient operating switch, the clutch of gear set was shafted to mesh different gear and causing direction change to forward or backward. This easy and convenient design allows patients to reverse FA/
LW in a narrow space. In addition, it is necessary to equip a neutral position. It can move wheelchair every where by caretaker when legs of patients are fatigue.
Eight hemiplegic patients were recruited to attend clinical evaluation. The results of evaluation revealed that FA/ LW is significant better than MW on the finiah time of maneuverability. Moreover, the PCI of LW and FAW is about 57.3 and 59.5% lower than MW, respectively. It meant that FA/ LW had higher propelling efficiency than that of MW. The MAS of affected leg reduced significantly after propelling FA/ LW, showed that the muscle tone of affected leg decreased. With regard to the results of clinical evaluation, FA/ LW were significant better than MW at maneuverability, propelling efficiency and muscle tone decreasing.
The maneuverability of the FA/ LW was superior to that of the MW in finishing the same course. It might be easier for hemiplegic patients to steer the FA/ LW by arm
than to control direction of the MW by the unaffected leg. For stroke patients, compare with wheeling MW which needed highly coordination ability of leg and arm to finish the course, FA/ LW only needed to propelling by legs and steering by arm. Accordingly, this operation manner provided better maneuverability than MW.
Hemiplegic patients using the FA/ LW in this study showed more efficient than to wheel the MW with the unaffected arm and leg. The present study revealed the same trends with the previous research [9], the efficiency of lower extremity-propelling wheelchairs were better than MW. The relatively large muscles of lower extremity had greater oxidative capacity, greater motor unit recruitment, differences in fibre type, and increased ability to generate tension. Therefore, there was higher efficiency for leg propelling compared with arm wheeling in the present study. The arm wheeling pattern was more complex and discontinuous than leg cycling. The extra energy loss would arise in the recovery phase due to acceleration and deceleration of the arms [20] [21].
Besides, It might be a better way to maintain/ improve cardiopulmonary function by strengthening large muscle groups of lower extremity than strengthening small muscle group of upper extremity [22] [23].
Many researches also pointed out that when stroke patients propelling manual wheelchair, it will induce contralateral abnormal muscle tone because of asymmetrical contribute situation [24] [25]. In clinical evaluation, although MAS of affected leg did not change significantly, but there were still two patients whose muscle tone of affected leg is increased. On the contrary, muscle tone of post-exercise was decrease significantly than pre-exercise in FA/ LW. The possible reason for decrease muscle tone of leg in FA/ LW was that cycling exercise is a multi-joint, coordination and symmetrical bilateral lower extremities exercise. It could provide passive stretch exercise for joints of lower extremity to reduce abnormal muscle tone and stretching ankle plantarflexors repeatly could reduce not only the elasticity of the hypertonic muscles, but also their viscosity in the stroke patients [26] [27].
6. Conclusion
The results of cardiopulmonary fitness demonstrated that there was no significant difference in with or without FES. The reason might stem from the same total workload and distance in propelling LW and FAW. Besides, the results of muscle tone demonstrated that there was no significant difference between with FES (FAW) and without FES (LW). The electrical stimulation for spasticity was base on mechanisms of facilitating Renshaw cell recurrent inhibition, antagonist reciprocal inhibition, and cutaneous sensory habituation. However the effect of electrical stimulation included biomechanical and neurological factors. The biomechanical effects of LW and FAW were almost the same. The benefit of solely electric stimulation to reduce spasticity is limited, but in clinical practice may be enhanced when movement is allowed during stimulation (FAW). Most contributions might came from repeated motion.
In the present study, the affected leg of hemiplegic patient was afforded low intensity stimulation current in FAW to achieve cycling motion exercise instead of passive driven by affected leg. However, the output force of the affected and the unaffected legs were not measured and the neurological factors were not clear in the present study. We can’t discriminate the difference of cardiopulmonary fitness and muscle tone between LW and FAW. In the future, more participants should be choosing to join the evaluation to realize the long term effect of FES.
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