Ben Yi Liau

Using local scale exponent to characterize heart rate variability in response to postural changes in people with spinal cord injury.

Heart rate variability (HRV) is a promising marker for evaluating the remaining autonomic function in people with spinal cord injury (SCI). HRV is commonly assessed by spectral analysis and detrended fluctuation analysis (DFA). This study aimed to investigate whether local scale exponent α(t) can reveal new features of HRV that cannot be reflected by spectral measures and DFA coefficients. We studied 12 participants with SCI and 15 healthy able-bodied controls. ECG signals were continually recorded during 10 min sitting and 10 min prone postures. α(t) was calculated for scales between 4 and 60 s. Because α(t) could be overestimated at small scales, we developed an approach for correcting α(t) based on previous studies. The simulation results on simulated monofractal time series with α between 0.5 and 1.3 showed that the proposed method can yield improved estimation of α(t). We applied the proposed method to raw RR interval series. The results showed that α(t) in healthy controls monotonically decreased with scale at scales between 4 and 12 s (0.083–0.25 Hz) in both the sitting and prone postures, whereas in participants with SCI, α(t) slowly decreased at almost all scales. The sharp decreasing trend in α(t) in controls suggests a more complex dynamics of HRV in controls. α(t) at scales between 4 (0.25 Hz) and around 7 s (0.143 Hz) was lower in subjects with SCI than in controls in the sitting posture; α(t) at a narrow range of scales around 12 s (0.083 Hz) was higher in participants with SCI than in controls in the prone posture. However, none of normalized low frequency (0.04–0.15 Hz) power, the ratio of low frequency power to high frequency (0.15–0.4 Hz) power and long-term (>11 beats) DFA coefficient showed significant difference between healthy controls and subjects with SCI in the prone posture. Our results suggest that α(t) can reveal more detailed information in comparison to spectral measures and the standard DFA parameters.

Plantar pressure gradient angles to evaluate risk of diabetic foot ulcer

Diabetic foot ulcers remain one of the most serious complications of diabetes mellitus. Peak pressure gradient (PPG) has demonstrated to contribute to the development of diabetic foot ulcers. This study used the time-varying directions of instantaneous PPG angle to evaluate the risk of diabetic foot ulcers. A total of 14 participants were studied, including 7 diabetics and 7 non-diabetic controls. The peak plantar pressure (PPP), PPG, and PPG angle at the great toe were calculated from plantar pressures obtained by the F-scan plantar pressure measurement system during walking. The results showed that the PPP and PPG in the diabetics were significantly higher than in the controls, but the PPG angle in the diabetics was significantly lower than in the controls. This study provides evidence that the diabetics are associated with higher PPP and PPG and lower PPG angle as compared to non-diabetics. The proposed PPG angle may improve our understanding of the influence of PPG on the risk for diabetic foot ulcers.

Effect of far infrared radiation therapy on improving microcirculation of the diabetic foot

Diabetes is associated with many severe complications, such as heart disease and nerve damage. Diabetics have elevated blood glucose levels that result in peripheral neuropathy. As a result, diabetics always feel painful about their lower limbs and may need to have lower limb amputation. The diabetic foot ulcers are hard to heal and require extensive medical treatments and follow ups. The purpose of this study was to evaluate the effect of infrared radiation therapy using a heating pad with carbon fibers (LinkWin Technology Co., Taiwan) on the diabetic foot. Ten diabetics and 4 non-diabetics were recruited for this study. The participants were assessed for their microvascular function before and after the interventions in each month for three consecutive months. The results showed that surface temperature increase by 2° after using the pad in the first and third months (p < 0.05); and blood flow increase on the plantar foot (p < 0.05) but not on the dorsal foot. The increase in blood flow may alleviate diabetic-related complications. The results of autonomic nervous testing indicated that the activity of sympathetic nervous increased after using the pad. In conclusion, the use of heating pad with far infrared radiation could improve blood flow and autonomic nervous system in diabetics, therefore improving alleviating symptoms of diabetes-related complications.

The Influence of Dry Cupping of Differing Intensities on Heart Rate Variability

The aim of this study was to determine an appropriate range of negative pressure to ensure the treatment effect of cupping. Twenty healthy participants were enrolled to receive classic dry cupping treatments at three different pressure intensities (−100, −300, or −500 mmHg) for 10 min each. Heart rate variability (HRV) was measured before, during, and 10 min after cupping to assess changes in autonomic activity. Repeated measure ANOVA was used to analyze differences. Cupping at a pressure of −100 mmHg did not significantly change the HRV, but cupping at both −300 and −500 mmHg caused a significant improvement in HRV. The HRV responses did not differ significantly between cupping at −300 and at −500 mmHg, however. The significant increase in HRV occurred only during the recovery period after the cups were removed.

Three-dimensional elastography gradient of the plantar soft tissue: Methodology and preliminary study

Diabetic foot ulcers are a significant complication in people with diabetes mellitus. The changes of mechanical properties of plantar tissues associated with diabetes may contribute to a high incidence of diabetic foot ulcers. This study investigated the feasibility of using three-dimensional (3D) elastography to measure 3D elasticity of the fat pad and then calculate 3D elasticity gradients of the foot. This method may improve the detection of people at risk for diabetic foot ulcer. Elastography with a soft ratio measurement may provide a visualization of plantar soft tissues for clinicians to diagnose foot ulcer risk. In this study, we measured B-mode and elastic ultrasound images at the first metatarsal head in five volunteers. The soft tissue contains four layers, including inner layer (Q1, near bone surface), sub-inner layer (Q2), sub-outer layer (Q3), and outer layer (Q4, near skin surface). The elasticity values were significantly greater in the Q3 layer compared to the Q1 layer. The elasticity gradient values were significantly smaller in the Q3 layer compared to the Q2 layer. The correlation between the elasticity and elasticity gradient was r = −0.88 in the Q3 layer.

Development of an Intermittent Pneumatic Compression System to Manage Soft Tissue Mechanical Properties

The pneumatic compression system has demonstrated the potential to manage hypertrophic scar tissues using localized intermittent compressive forces. The underlying mechanism associated with these repeated, intermittent compressive forces is the remodeling capacity of collagen fibers of fibrous tissues in response to mechanical forces. Although intermittent compressive forces are clinically proven effective on managing hypertrophic scar, the optimal configurations of pressures and timing of intermittent compressive forces are largely unknown. In this study, we have developed a motor-driven ultrasound indentation system to apply programmable compressive forces and simultaneously assess soft tissue mechanical properties and responses. We further tested this system in various conditions with Institutional Review Board-approved protocols in human participants. The compressive force applied by the system was 40 mmHg on the skin of the forearm for 1 h with a frequency of 0.1 Hz. Soft tissue mechanical properties were assessed at three conditions, including (a) the forearm resting on the table with the wrist at a neutral position, (b) the forearm resting on the table with the wrist at 90° of extension or the maximal extension of the subject, and (c) forearm resting on the table with the hand holding a 1 kg weight. The effective Young’s modulus was calculated to characterize mechanical properties of forearm soft tissues. Before the 1 h intermittent compression treatment, effective Young’s modulus of conditions a, b, and c was 18.0, 11.3, and 16.8 kPa, respectively. After the treatment, the effective Young’s modulus of conditions a, b, and c was reduced by 13, 7, and 51 %, respectively. The results support our general hypothesis that intermittent compression therapy may modulate soft tissue properties (e.g. hypertrophic scar). Future work should investigate the long-term effect of intermittent compression therapy on modulating soft tissue properties in patients with hypertrophic scars.

A Comparative Study of the Effects of Electrical Stimulation and Intermittent Compressive Forces on Soft Tissue Mechanical Properties

We aimed to investigate and compare the effects of electrical stimulation and intermittent compressive forces on soft tissue mechanical properties. Four healthy individuals were recruited into this study. A transcutaneous electrical stimulation device was used to apply a pulse duration of 2.5 ms, a frequency of 2 Hz, and the amplitude to a maximum of 30 mA. The intermittent compressive forces were applied at a period of 20 s with forces ranging from 0 to 70 mmHg. The effective Young’s modulus was calculated to characterize mechanical properties of forearm soft tissues. The results showed that forearm soft tissue properties might decrease effective Young’s modulus after the treatments of electrical stimulation and intermittent compressive forces.

Activation Sequence Patterns of Forearm Muscles for Driving a Power Wheelchair

The purpose of this study was to investigate muscle activities of the upper limbs while driving a power wheelchair. Eleven healthy individuals were recruited to perform four joystick control tasks, including forward, backward, left-turn, and right-turn. The results of this study would establish a norm for evaluating the controls of a power wheelchair in children with cerebral palsy. The surface electromyographic monitor (EMG) was used to record the contractions of extensor carpi ulnaris (ECU), flexor carpi ulnaris (FCU), and flexor carpi radialis (FCR). The integration of EMG signals was used to quantify the muscle efforts. The results showed that participants use more muscle efforts in ECU during backward early, but during left-turn later. The results of the forearm muscle activations can be used to guide training of children with cerebral palsy to drive a power wheelchair.

The Effects of Cupping Therapy on Reducing Fatigue of Upper Extremity Muscles—A Pilot Study

The aim of this study was to determine the effect of the cupping therapy on the muscles and autonomic nervous system. Five healthy participants were recruited for the arm cranking tests. The protocols include a 1st 12-min bout, 20-min recovery, and 2nd 12-min bout. The cupping therapy (negative pressure of 300–450 mmHg on the upper back and shoulder muscles) was applied during the recovery period of experimental trials. The median frequency (MDF) of electromyographic signals and the heart rate variability (HRV) were used to objectively quantify the degree of muscle fatigue and cardiovascular regulations. The repeated measures ANOVA was applied to determine the differences. Our results showed that MDF was significantly higher in the experimental trials but the HRV was not significantly different between the experimental and control trials. Our study indicates that the role of cupping therapy may reduce muscle fatigue but do not alter the cardiorespiratory controls.

Electromyographic Assessments of Muscle Activation Patterns During Driving a Power Wheelchair

Power wheelchairs are essential for cerebral palsy children with mobility impairments. The purpose of this study was to establish a muscles sequence pattern of the upper limbs to help clinicians determine a child’s readiness to control the joystick for maneuvering a power wheelchair. Five individuals performed four joystick control tasks, including forward, backward, left-turn, and right-turn. The X/Y positions of joystick and surface electromyographic (EMG) signals were record simultaneously. The surface EMG was used to record the contraction of four right upper limbs muscles, including extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), pronator teres (PNT), and deltoid anterior (DA). A technique for analyzing and comparing the dynamic patterns of EMG collected during driving a power wheelchair was presented. Driving EMG patterns were computed to consist of both magnitude (amplitude) and phase (timing) components. For the magnitude component, the magnitude component of the EMG patterns is defined as the muscle during rest, slight contraction, or forceful contraction. The phase component of the EMG patterns is defined as the muscles of contraction duration with active or inactive regions in each joystick control task. The results showed that participants use more muscle efforts of the ECU and ECR compared to PNT and DA during four joystick control tasks. The active regions of the phase component were similar between the ECU and ECR. There were more phase component of forceful muscle contraction of the ECU compared to ECR during left-turn task. PNT muscles did not contract during the right-turn task. DA muscles were only slight contraction during the forward task. The findings imply that the joystick control strategy for power wheelchairs may be profiled by the muscle sequence patterns of the wheelchair users.