Adaptive cancellation of the respiratory artifact in surface recording of small intestinal electrical activity

In the human small intestine there is omnipresent electrical activity with a frequency of 0.15–0.2 Hz. The electrical activity of the small intestine can be measured by surface electrodes placed on the abdominal skin. The most annoying problem in the surface electrical recording is the respiratory artifact which is not discernible from the small intestinal signal. The frequency of the respiration is about 0.2–0.4 Hz, which is very close to that of small intestinal activity, making the use of the conventional bandpass filtering impractical. In this paper a selective frequency domain adaptive filter was proposed for the cancellation of the respiratory artifact. The basic principle of the selective frequency domain adaptive filter is that only selected filter weights are adapted based on the frequency characteristics of the respiratory artifact. Therefore, a substantial reduction of computation is achieved. A series of computer simulations was conducted for the optimization of the system parameters and for the investigation of the system performace. It was demonstrated in this paper that the selective frequency domain adaptive filter is as effective as, but more efficient than, the conventional frequency domain adaptive filter. The adaptive system for the cancellation of the respiratory artifact based on the selective frequency domain adaptive filter is very efficient in computation, has a fast convergence (about 100 adaptations), substantial reduction of the respiratory artifact and little effect (or distortion) on the small intestinal electrical signal.     

An ergonomic comparison of in-line vs pistol-grip handle configuration in a laparoscopic grasper

Background: Laparoscopic instruments incorporate both in-line and pistol-grip handle configurations, yet it is unclear which design is most advantageous for surgeons, particularly when operating at angles perpendicular to the surgeon's position. We present a detailed electromyographic (EMG) comparison of these handle configurations under different force and angle conditions. Methods: Nine general surgeons used a Microsurge grasper with the handle in an in-line (MS-IL) and pistol (MS-PS) configuration, as well as a standard hemostat (HE), to grasp and close two spring-loaded metal plates. The task was performed randomly by each subject with the three instrument configurations at two forces levels (0.7 N, 4.2 N) and at three angles to the surgeons' body (0, 45, and 90°). Surface EMG was measured from the flexor carpi ulnaris (FCU), flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS), extensor carpi ulnaris (ECU), extensor digitorum comunis (EDC), and thenar compartment (TH). The peak root mean squared (RMS) EMG voltage was calculated for each instrument, force, and angle condition. Statistical comparison was carried out by ANOVA. Results: Both laparoscopic handle configurations required significantly higher contractions of all muscle groups compared to the hemostat at the high force level. TH was not affected by laparoscopic handle configuration. MS-IL required higher FCU, ECU, and EDC contractions at 45° compared to MS-PS. However, MS-IL decreased the flexor compartment muscle contractions (FDP, FDS, FCU) at 90° compared to MS-PS. Conclusions: Laparoscopic grasping requires higher forearm and thumb muscle contractions compared to the use of a hemostat. The in-line handle configuration is no better than the pistol configuration except when grasping at 90° to the surgeon, where rotation of the handle and wrist back toward the surgeon significantly decreases forearm flexor compartment muscle contractions. Received: 3 April 1997/Accepted: 10 August 1997     

尼莫地平治疗糖尿病周围神经病变的临床研究

目的观察尼莫地平对糖尿病周围神经病变患者肌电图及血液流变学的影响。方法将71例糖尿病周围神经病变患者随机分为两组,对照组30例予以传统的治疗,治疗组41例在此基础上加用尼莫地平口服治疗;观察尼莫地平对肌电图及血液流变学的影响。结果经尼莫地平治疗6个月后,治疗组的神经症状、体征及正中神经、胫神经MCV和SCV的改善极显著(P<0.01),对血液流变学指标有明显改善(P<0.05),均优于对照组。结论尼莫地平治疗糖尿病周围神经病变有较好疗效。     

胸段脊旁肌肌电图在肌萎缩侧索硬化诊断中的作用

目的 研究胸段脊旁肌自发电位在诊断肌萎缩侧索硬化(amyotrophic lateral sclerosis，ALS)中的价值。方法 50例确诊的ALS患者分别行胸段脊旁肌自发电位、胸锁乳突肌运动单位，部分患者行舌肌自发电位检测；同时，将性别、年龄相匹配的30例根性损害的患者和30名健康人作为对照，行胸段脊旁肌自发电位检测。结果 50例ALS患者中，41例(82％)胸段脊旁肌肌电图可见大量纤颤电位和正锐波；胸锁乳突肌肌电图无一例见自发电位，但有48例(96%)运动单位时限增宽，波幅增高，符合慢性神经源性损害改变；6例患者行舌肌自发电位检测，3例可见自发电位。30例根性病变的患者中，2例(7％)可见胸段脊旁肌有少量自发电位；健康对照组未见胸段脊旁肌自发电位。结论 胸段脊旁肌大量自发电位对诊断ALS具有一定的敏感性。     

Electromyography of the muscles of oropharyngeal swallowing: Basic concepts

Electromyography (EMG) has a valuable role in the evaluation of swallowing and its disorders, because it can assess the activity of individual muscles. Electromyographic kinesiology is a method for examining the physiology of swallowing. Analysis of individual myoelectric potentials is a technique for studying the integrity of the motor unit. This paper introduces the concepts of the motor unit, explains basic principles of EMG, and explores their relevance to the study of oropharyngeal swallowing. Several cases are presented to illustrate how EMG contributes to clinical diagnosis.     

Neuromuscular monitoring

Neuromuscular monitoring is central to the rational use of neuromuscular blocking agents. Stimulation of a peripheral nerve by electrical or magnetic means is followed by contraction of a voluntary muscle. Single impulses may be used but more commonly impulses are given in groups. The train of four, double burst and post-tetanic count are those trains usually employed clinically. Almost any skeletal muscle can be used but those of the hand, face and leg are most commonly employed as they are the easiest to both stimulate and record from. The responses of muscles may be measured by direct visual or tactile means. More accurate methods include mechanomyography, electromyography and accelerometry.     

兔坐骨神经钳夹伤后的电生理研究

本文对兔坐骨神经钳夹伤后的电生理研究结果表明：１．神经损伤后第１０天肌电图（ＥＭＧ）表现有插入电位延长，延长时间随神经再生而逐渐缩短。２．损伤后第２０天可记录到再生小电位。３．诱发肌肉收缩电位于神经损伤后３０天可记录到，４．推算神经再生速度平均为２．８３ｍｍ／日，最快可达４ｍｍ／日。本研究旨在对神经再生的临床判断及有关研究提供参考。     

Oral nutritional supplement fortified with beta-alanine improves physical working capacity in older adults: A randomized,placebo-controlled study

This study examined the effects of an oral nutritional supplement fortified with two different doses of beta-alanine on body composition, muscle function and physical capacity in older adults. Using a double-blind placebo controlled design, 60 men and women (age ± SD = 70.7 ± 6.2 yrs) were randomly assigned to one of three treatment groups: 1) oral nutritional supplement (ONS; n = 20) (8 oz; 230 kcal; 12 g PRO; 31 g CHO; 6 g FAT), 2) ONS plus 800 mg beta-alanine (ONS800; n = 19), and 3) ONS plus 1200 mg beta-alanine (ONS1200; n = 21). Treatments were consumed twice per day for 12 weeks. At pre- and post-supplementation period, participants performed a discontinuous, submaximal cycle ergometry test to determine physical working capacity at fatigue threshold (PWCFT). Fat mass, total body and arm lean soft tissue mass (ALSTM) were measured with DEXA while muscle strength was assessed with handgrip dynamometry (GRIP) and 30-s sit-to-stand (STS) was used to measure lower body functionality. Muscle quality (MQ) was calculated with GRIPmax and DEXA derived ALSTM [GRIP (kg)·ALSTM (kg)^− 1]. Two-way analysis of variance was used to compare pre- to post-supplementation measures and group differences. There were 16 dropouts over the duration of the study. Final group sizes were ONS = 16 (m = 11, w = 5), ONS800 = 15 (m = 5, w = 10), and ONS1200 = 13 (m = 6, w = 7). No significant changes were observed for body composition or GRIP values pre to post. Significant increases in PWC_FT were seen in ONS1200 (13.6%) and ONS800 (17.8%) pre- to post-supplementation (p < 0.05). These changes were significantly greater (p < 0.05) than the changes in ONS (− 6.3%). ONS1200 and ONS had significant increases in STS (22.2 and 10.7%, respectively). While ONS significantly increased in STS, no differences (p > 0.05) in change scores were found between ONS and ONS800. ONS fortified with beta-alanine may improve physical working capacity, muscle quality and function in older men and women. These findings could have importance in the perception of frailty, and the maintenance of health and independent living in older adults.     

Physiological Responses to Spinal Manipulation Therapy: Investigation of the Relationship Between Electromyographic Responses and Peak Force

Objective

It is believed that systematic modulation of spinal manipulative therapy (SMT) parameters should yield varying levels of physiological responses and eventually a range of clinical responses. However, investigation of SMT dose–physiological response relationship is recent and has mostly been conducted using animal or cadaveric models. The main objective of the present study is to investigate SMT dose–physiological response relation in humans by determining how different levels of force can modify electromyographic (EMG) responses to spinal manipulation.

Methods

Twenty-six participants were subjected to 2 trials of 4 different SMT force-time profiles using a servo-controlled linear actuator motor. Normalized EMG activity of paraspinal muscles (left and right muscles at level T6 and T8) was recorded during and after SMT, and EMG values were compared across the varying levels of force.

Results

Increasing the level of force yielded an increase in paraspinal muscle EMG activity during the thrust phase of SMT but also in the two 250-millisecond time windows after the spinal manipulation impulse. These muscle activations quickly attenuated (500 milliseconds after spinal manipulation impulse).

Conclusion

The study confirmed the presence of a local paraspinal EMG response after SMT and highlighted the linear relationship between the SMT peak force and paraspinal muscle activation.     

Interlimb Coordination During the Stance Phase of Gait in Subjects With Stroke

Objective

To analyze the relation between contralesional and ipsilesional limbs in subjects with stroke during step-to-step transition of walking.

Design

Observational, transversal, analytical study with a convenience sample.

Setting

Physical medicine and rehabilitation clinic.

Participants

Subjects (n=16) with poststroke hemiparesis with the ability to walk independently and healthy controls (n=22).

Interventions

Not applicable.

Main Outcome Measures

Bilateral lower limbs electromyographic activity of the soleus (SOL), gastrocnemius medialis, tibialis anterior, biceps femoris, rectus femoris, and vastus medialis (VM) muscles and the ground reaction force were analyzed during double-support and terminal stance phases of gait.

Results

The propulsive impulse of the contralesional trailing limb was negatively correlated with the braking impulse of the leading limb during double support (r=−.639, P=.01). A moderate functional relation was observed between thigh muscles (r=−.529, P=.035), and a strong and moderate dysfunctional relation was found between the plantar flexors of the ipsilesional limb and the vastus medialis of the contralesional limb, respectively (SOL-VM, r=−.80, P<.001; gastrocnemius medialis-VM, r=−.655, P=.002). Also, a functional moderate negative correlation was found between the SOL and rectus femoris muscles of the ipsilesional limb during terminal stance and between the SOL (r=−.506, P=.046) and VM (r=−.518, P=.04) muscles of the contralesional limb during loading response, respectively. The trailing limb relative impulse contribution of the contralesional limb was lower than the ipsilesional limb of subjects with stroke (P=.02) and lower than the relative impulse contribution of the healthy limb (P=.008) during double support.

Conclusions

The findings obtained suggest that the lower performance of the contralesional limb in forward propulsion during gait is related not only to contralateral supraspinal damage but also to a dysfunctional influence of the ipsilesional limb.