Intramuscular pressure, tissue oxygenation and EMG fatigue measured during isometric fatigue-inducing contraction of the multifidus muscle

Simultaneous measurement of intramuscular pressure (IMP), tissue oxygen partial pressure (pO₂) and EMG fatigue parameters in the multifidus muscle during a fatigue-inducing sustained muscular contraction. The study investigated the following hypotheses: (1) Increases in IMP result in tissue hypoxia; (2) Tissue hypoxia is responsible for loss of function in the musculature. The nutrient supply to muscle during muscle contraction is still not fully understood. It is assumed that muscle contraction causes increased tissue pressure resulting in compromised perfusion and tissue hypoxia. This tissue hypoxia, in turn, leads to muscle fatigue and therefore to loss of function. To the authors knowledge, no study has addressed IMP, pO₂ and EMG fatigue parameters in the same muscle to gain a deeper sight into muscle perfusion during contraction. As back muscles need to have a constant muscular tension to maintain trunk stability during stance and locomotion, muscle fatigue due to prolonged contraction-induced hypoxia could be an explanation for low back pain. Sixteen healthy subjects performed an isometric muscular contraction exercise at 60% of maximum force until the point of localized muscular fatigue. During this exercise, the individual changes of IMP, pO₂ and the median frequency (MF) of the surface EMG signal of the multifidus muscle were recorded simultaneously. In 12 subjects with a documented increase in intramuscular pressure, only five showed a decrease in tissue oxygen partial pressure, while this parameter remained unchanged in six other subjects and even increased in one. A fall in tissue pO₂ was associated with a drop in MF in only five subjects, while there was no correlation between these parameters in the other 11 subjects. To summarize, an increase in IMP correlated with a decrease in pO₂ and a drop in MF in only five out of 16 subjects. High intramuscular pressure values are not always associated with a hypoxia in muscle tissue. Tissue hypoxia is not automatically associated with a median frequency shift in the EMG signals power spectrum.C. Dehner and E. Hartwig contributed to this work equally. The experiments comply with the current laws of Germany and were performed inclusive of ethics approval     

Design and evaluation of a new ergonomic handle for instruments in minimally invasive surgery

Background

Laparoscopic surgery techniques have been demonstrated to provide massive benefits to patients. However, surgeons are subjected to hardworking conditions because of the poor ergonomic design of the instruments. In this article, a new ergonomic handle design is presented. This handle is designed using ergonomic principles, trying to provide both more intuitive manipulation of the instrument and a shape that reduces the high-pressure zones in the contact with the surgeon's hand.

Materials and methods

The ergonomic characteristics of the new handle were evaluated using objective and subjective studies. The experimental evaluation was performed using 28 volunteers by means of the comparison of the new handle with the ring-handle (RH) concept in an instrument available on the market. The volunteers' muscle activation and motions of the hand, wrist, and arm were studied while they performed different tasks. The data measured in the experiment include electromyography and goniometry values.

Results

The results obtained from the subjective analysis reveal that most volunteers (64%) preferred the new prototype to the RH, reporting less pain and less difficulty to complete the tasks. The results from the objective study reveal that the hyperflexion of the wrist required for the manipulation of the instrument is strongly reduced.

Conclusions

The new ergonomic handle not only provides important ergonomic advantages but also improves the efficiency when completing the tasks. Compared with RH instruments, the new prototype reduced the high-pressure areas and the extreme motions of the wrist.     

Paraspinal strength and electromyographic fatigue in patients with sub-acute back pain and controls: Reliability,clinical applicability and between-group differences

BACKGROUNDParaspinal muscle strength and fatigue are considered important in low back pain (LBP) prevention and rehabilitation. High reliability of paraspinal strength and electromyographic (EMG)-fatigue parameters has not been universally reported. Moreover, the discriminative validity of these parameters requires further exploration, under the threat of potentially poor reliability of the methods examined.AIMTo investigate the reliability and discriminative validity of paraspinal strength and EMG-related fatigue in subjects with recurrent LBP and healthy participants.METHODSTest-retest measurements were performed in 26 healthy and 66 LBP volunteers, for reliability. Paraspinal isometric maximal and mean strength were determined with a maximum voluntary isometric contraction (MVIC) protocol, performed in a custom-made device. For the fatigue test, participants performed a 60% MIVC level continuous isometric contraction of the paraspinals, in conjunction with EMG analysis from 4 muscle sites of the lumbar spine. Initial median frequency (IMF), the median frequency slope (MFslope), as well as the root mean square (RMS) slope EMG parameters were used as fatigue measures. Data were analysed with repeated measures ANOVA for test-retest differences. For reliability, the intraclass correlation coefficient (ICC_3,1), standard error of the measurement (SEM) and the smallest detectable difference (SDD) were reported. Group-related differences for fatigue measures were analysed with a Multivariate Analysis of Covariance, with age, weight and strength as covariates.RESULTSIsometric strength presented statistically significant between-day differences (P < 0.01), however these did not exceed 10% (healthy: 7.2%/LBP-patients: 9.7%) and ICC reliability values were excellent, yet test-retest error was increased for the patient group (healthy: ICC_3,1: 0.92-0.96, SEM: 5.72-5.94 Hz, SDD: 18.51%-18.57%/LBP-patients: ICC_3,1: 0.91-0.96, SEM: 6.49-6.96, SDD: 30.75%-31.61%). For the frequency data, IMF reliability was excellent (healthy: ICC_3,1: 0.91-0.94, SEM: 3.45-7.27 Hz, SDD: 9.56%-20.14%/patients: ICC_3,1: 0.90-0.94, SEM: 6.41-7.59 Hz, SDD: 17.75%-21.02%) and of MF raw and normalised slopes was good (healthy: ICC_3,1: 0.78-0.82, SEM: 4.93-6.02 Hz, SDD: 13.66-16.67%/LBP-patients: ICC_3,1: 0.83-0.85, SEM: 6.75-7.47 Hz, SDD: 18.69%-20.69%). However, the reliability for RMS data presented unacceptably high SDD values and were not considered further. For discriminative validity, less MVIC and less steep MFslopes were registered for the patient group (P < 0.01).CONCLUSIONReliability and discriminative ability of paraspinal strength and EMG-related frequency parameters were demonstrated in healthy participants and patients with LBP.     

社会支持在慢性肝衰竭患者自我表露与疲乏间的中介效应

目的 探讨慢性肝衰竭患者社会支持与自我表露、疲乏的关系,为采取针对性措施减轻患者的疲乏提供参考。方法 采用一般资料调查表、多维疲乏量表-20、痛苦表露指数量表修订版、领悟社会支持量表对126例慢性肝衰竭患者进行调查分析。结果 慢性肝衰竭患者社会支持得分(56.30±5.96)分,疲乏(58.39±3.15)分,自我表露(36.79±2.45)分;患者的社会支持与自我表露呈正相关,与疲乏呈负相关(均P<0.05);社会支持在自我表露与疲乏间起部分中介作用,中介效应占总效应的34.59%。结论 慢性肝衰竭患者的自我表露对疲乏有直接预测作用,社会支持在自我表露与疲乏间起部分中介作用。促进患者的自我表露,提高社会支持是降低患者疲乏感的有效途径。     

肺癌患者化疗前后睡眠障碍、情绪状态和疲劳程度的变化及相关性

目的研究肺癌患者一个化疗周期中的疲劳、睡眠障碍及情绪状态的变化及各变量之间的关系。方法选择75例初诊肺癌患者,采用一般疲劳量表、匹兹堡睡眠质量指数、简式情绪状态量表,于第1次化疗前1d(T0)、第1次化疗后1周(约第28天,T1)及第2次化疗前2～4h(T2)共3个时间点进行测量。结果男、女性肺癌患者在3个时间点的疲劳程度、睡眠障碍、焦虑及抑郁得分比较,差异有统计学意义(均P<0.01);无论男女性别之分或不同治疗方式之分,3个时间点的疲劳、睡眠障碍、焦虑及抑郁均具有显著的时间效应(均P<0.01);3个测量时间点疲劳、睡眠障碍、焦虑及抑郁均有显著的相关性(P<0.05,P<0.01)。结论肺癌患者化疗周期间其疲劳、睡眠障碍及情绪状态存在长期变化,且疲劳与睡眠障碍、焦虑及抑郁之间存在相关性。护理人员应加强对这类人群的关注度以及开展相关知识的健康教育,及时了解肺癌患者治疗期间疲劳、睡眠障碍及焦虑、抑郁情况,并针对性地加强护理管理力度。     

Nonsurgical treatment and early return to activity leads to improved Achilles tendon fatigue mechanics and functional outcomes during early healing in an animal model

Achilles tendon ruptures are common and devastating injuries; however, an optimized treatment and rehabilitation protocol has yet to be defined. Therefore, the objective of this study was to investigate the effects of surgical repair and return to activity on joint function and Achilles tendon properties after 3 weeks of healing. Sprague–Dawley rats (N = 100) received unilateral blunt transection of their Achilles tendon. Animals were then randomized into repaired or non‐repaired treatments, and further randomized into groups that returned to activity after 1 week (RTA1) or after 3 weeks (RTA3) of limb casting in plantarflexion. Limb function, passive joint mechanics, and tendon properties (mechanical, organizational using high frequency ultrasound, histological, and compositional) were evaluated. Results showed that both treatment and return to activity collectively affected limb function, passive joint mechanics, and tendon properties. Functionally, RTA1 animals had increased dorsiflexion ROM and weight bearing of the injured limb compared to RTA3 animals 3‐weeks post‐injury. Such functional improvements in RTA1 tendons were evidenced in their mechanical fatigue properties and increased cross sectional area compared to RTA3 tendons. When RTA1 was coupled with nonsurgical treatment, superior fatigue properties were achieved compared to repaired tendons. No differences in cell shape, cellularity, GAG, collagen type I, or TGF‐β staining were identified between groups, but collagen type III was elevated in RTA3 repaired tendons. The larger tissue area and increased fatigue resistance created in RTA1 tendons may prove critical for optimized outcomes in early Achilles tendon healing following complete rupture. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2172–2180, 2016.     

新型冠状病毒肺炎疫情期方舱医护人员共情疲劳及影响因素分析

目的了解新型冠状病毒肺炎疫情期方舱医护人员共情疲劳现状及其影响因素。方法应用专业生活质量量表(ProQOL)和心理弹性量表(CD-RISC)对在武汉市3所方舱医院工作的219名医护人员进行问卷调查。结果方舱医院医护人员共情疲劳得分为共情满意维度(38.74±7.83)分,职业倦怠维度(21.64±5.05)分,继发性创伤应激维度(20.90±6.29)分;其中轻度共情疲劳105人(47.95%),中度共情疲劳32人(14.61%),重度共情疲劳23人(10.50%);共情疲劳受医护人员工作单位所在省份、突发公共卫生事件工作史、方舱工作时间、工作环境适应情况、工作负荷、睡眠情况、心理弹性的影响(P0.05,P0.01)。结论新型冠状病毒肺炎疫情下医护人员共情疲劳现象普遍存在,可通过加强突发公共卫生事件相关培训与督导、合理人力资源管理、创造良好的工作氛围、加强一线医护人员人文关怀等措施帮助改善共情疲劳状态,维护医护人员的身心健康。